Softened flash-spun sheet

Abstract

The present invention relates to (i) a bonded sheet of nonwoven flash-spun plexifilamentary fibrils exhibiting good barrier properties and a high degree of breathability and a moderate stiffness, (ii) a process for the preparation of a bonded sheet of nonwoven flash-spun plexifilamentary fibrils, and (iii) multilayer sheet structures and articles comprising at least one bonded sheet of nonwoven flash-spun plexifilamentary fibrils.

Description

[0001] TITLE

[0002] SOFTENED FLASH-SPUN SHEET

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to (i) a bonded sheet of nonwoven flash-spun plexifilamentary fibrils exhibiting good barrier properties and a high degree of breathability and a moderate stiffness, (ii) a process for the preparation of a bonded sheet of nonwoven flash-spun plexifilamentary fibrils, and (iii) a multilayer sheet structure and an article comprising the bonded sheet of nonwoven flash-spun plexifilamentary fibrils.

[0005] BACKGROUND

[0006] Flash-spun nonwoven materials have been developed with wide-ranging properties suitable for use in a variety of applications, including, but not limited to, active packaging, in which an active substance is enclosed within a gas permeable selective barrier to form a protective package. The active package controls, reacts, or interacts with its contents or the environment in a container to optimize storage or transport conditions for articles also held within the container. Examples of active substances within active packaging are desiccants used for protection from humidity, oxygen absorbers to prevent oxidation, and ethylene scavengers for preservation of fruits and vegetables.

[0007] The production of such nonwoven materials usually involves two stages, a first stage in which fibrils are produced and laid down in an overlapping manner to produce a fibril assembly in the form of a sheet, and a second stage in which adjacent fibrils are bonded via thermal bonding to obtain a robust structure which cannot be easily disassembled. The properties of the final nonwoven sheet are impacted by various factors from the first and second stages.

[0008] Flash-spinning is a method for producing fibrils having a unique plexifilamentary structure. It involves preparing a solution of a fibril-forming polymer in a spin agent at a pressure above the vapor pressure of the spin agent and at a temperature above the normal boiling point of the spin agent, and releasing that solution into a zone of substantially lower temperature and pressure such that the spin agent flash evaporates and the polymer solidifies in the form of plexifilamentary fibrils. Examples of flash spinning processes are disclosed in US 3,081 ,519 and US 3,227,794.

[0009] The properties of flash-spun fibrils depend on, among other factors, the polymer or blend of polymers used to form them, the spin-agent used to produce the spin-fluid, the concentration of polymer in the spin-fluid, and the temperature of the spin-fluid during spinning.As with other types of spinning technology, the properties of an initial fibril assembly are modified by subsequent thermal bonding to produce a flash-spun nonwoven sheet.

[0010] Thermal bonding is a common process for bonding nonwoven sheets in which heat is used to melt the polymer from which the fibrils are made, typically, by passing the nonwoven sheet through an arrangement of heated rolls. One or more back-up rolls, which form nips with the heated rolls to add pressure, may optionally be used. The degree of bonding can vary based on the temperature and pressure, and time during which these are applied. Bonding of the nonwoven sheet also varies spatially depending on the rolls used and area to which the bonding is applied, e.g., using smooth surfaced rolls to apply uniform heat and pressure over the entire surface versus using patterned rolls to apply heat and pressure locally over only a portion of the surface to form an embossed pattern in the final nonwoven sheet.

[0011] US 3,442,740 and US 3,532,589 describe thermal bonding on a smooth heated roll where one or both sides of the nonwoven sheet are subjected to generally uniform, whole surface contact thermal bonding. In this process, a surface bonded nonwoven sheet product is obtained having a paper-like feel and a high stiffness. Thermal bonding using a thermal calender bonder, such as that described in US 5,972,147, also tends to produce a stiffer nonwoven sheet product. The smooth surface and relatively high stiffness of such whole surface bonded nonwoven sheet products makes them suitable for uses such as packaging, print media and construction membranes. However, while a certain level of stiffness is required in breathable barriers used in active packaging, very high stiffness is a disadvantage as it makes folding and pleating to form a sachet more difficult, can cause seals to reopen on high speed filling machines, and prevents finished sachets from being able to conform their shape to the shape of their internal contents and the articles they are protecting. A moderate level of stiffness and flexibility is therefore desired in breathable barrier materials for active packaging.

[0012] US 3,478,141 and US 4,091 ,137 describe thermal bonding carried out by passing nonwoven sheets between heated engraved embossing rolls and rubber-coated back-up rolls to bond one or both sides of the nonwoven sheet only in defined areas, producing softer and more drapable materials suitable for use in garment applications. The embossing roll can contain different patterns, such as a point pattern as described in US 3,478,141 , US 6,610,390, and US 2004 / 241399 A1 , a rib pattern as described in US 2003 / 0032355 A1 and US 2003 / 00165667 A1 , a linen pattern ora random pattern as described in US 7,744,989, or a combination of different patterns as described in US 5,620,779 and US 5,964,742. The nonwoven sheet may pass through one or multiple pairs of a heated embossing roll and a rubber-coated back-up roll and may also wrap partially around one or more heated embossing rolls to transfer heat into the nonwoven sheet prior to reaching the nip between any such embossing roll and rubber-coated back-up roll. In addition, the nonwoven sheet may be incontact with one or more pre-heating or cooling rolls before and after passing through each pair of embossing and back-up rolls, in a configuration as described in US 5,972,147. US 6,034,008 and US 2003 / 00165667 A1 describe a process in which one side is embossed with a “rib” pattern of discrete bond points and the other side is embossed over a substantial portion of the surface with a “linen” pattern.

[0013] Thermal bonding impacts different properties of the nonwoven sheet in different ways. The flux properties of nonwoven sheets, i.e., the ability of the fibril assembly to allow free movement of air or other gases such as water vapor through it, either by diffusion or by bulk flow under a pressure difference, may be altered in different ways depending on the bonding process. Heating can lead to relaxation of tension within the fibrils and fibril shrinkage, resulting in an increase in the space between the fibrils and an increase in flux. Conversely, pressure applied during bonding can compress the structure, reducing the space between the fibrils through which gases can move, resulting in a decrease in flux. Moreover, if temperatures and pressures are high enough to cause fibrils to melt and fuse together extensively, this can create film-like regions which allow very little flux.

[0014] The barrier properties of nonwoven sheets, i.e., the ability of the fibril assembly to prevent particles in the air from passing through it, or liquids such as water to penetrate it under pressure, tend to change in the converse manner after bonding as, for instance, reduced pore sizes created by compression during bonding result in greater resistance to the passage of particles or liquids through the structure.

[0015] Mechanical properties such as delamination strength, abrasion resistance, and tensile strength may increase or decrease as the degree of bonding increases. However, the stronger connections between fibrils resulting from bonding, and the limitation of their ability to move relative to each other, increase the stiffness of the bonded sheet.

[0016] These complex interactions of behaviors mean that thermally bonding a nonwoven sheet to produce a product for a particular application typically requires a compromise in the desired properties of the final sheet.

[0017] The effect of bonding on sheet stiffness is especially notable when bonding is applied uniformly over the whole surface. This results in sheets having a paper-like texture often referred to as “hard-structures” which tend to produce a lot of noise when flexed or bent. When embossed rolls are used to create areas having greater and lesser degrees of bonding, quieter and more flexible, softer, fabric-like structures can be achieved, often referred to as “soft-structures.” However, even soft-structure bonded sheets are stiffer and less flexible than the starting sheet before bonding.

[0018] It is possible to recover some softness in a bonded, nonwoven sheet, by applying processes known in the textile industry such as softening or relofting. The term “relofting” denotes a post-processing step that increases the loft (i.e., lowers the solidity) of a bondednonwoven sheet. In these processes, the sheet is passed through equipment which locally distorts the material in a way that breaks or partially breaks some of the bonding between fibrils, allowing more relative motion and increasing the flexibility of the sheet. These changes in mechanical properties are typically accompanied by an increase in flux properties and a loss in barrier properties.

[0019] US 3,408,709 describes a softening process using a button breaker to mechanically soften a nonwoven sheet. The button breaker employs knobbed rolls which move at a different speed than, or even in the opposite direction than, that of the nonwoven sheet as the nonwoven sheet travels over the knobbed rolls, creating a rubbing effect.

[0020] US 5,966,785 and US 6,195,854 report a mechanical softening process where the nonwoven sheet is passed through the nip of a knobbed roll against a soft rubber backup roll. However, no information is given in these documents on how this process impacts the barrier properties of the nonwoven sheet.

[0021] US 7,296,328 discloses a process for the softening of a nonwoven sheet in which, with increasing softening cycles, the sheet shows an increase in breathability. The described softening process employs a rubbing effect using a speed difference between the nonwoven sheet and the roller or mechanical object over which it passes. However, since the nonwoven sheet is exposed to a rubbing surface, its surface is damaged.

[0022] US 3,920,874 and US 3,811 ,979 describe a process employing pairs of softening rolls covered with square edged cylindrical pins which interlock for the softening of a nonwoven sheet that passes between them, with the softening rolls moving at the same surface speed as the nonwoven sheet. The nonwoven sheet is required to have an elongation of at least 10 % for the process to work correctly.

[0023] WO 2020 / 026062 A1 describes a process that includes a type of mechanical softening of a nonwoven sheet known as relofting. The nonwoven sheets are made from melt spun or melt blown fibers and are potentially charged. According to the document, when the nonwoven sheet has a solidity of no more than 10 %, relofting reduces the pressure drop of a nonwoven sheet while having a negligible effect on its filtration efficiency. But when the nonwoven sheet has a solidity of 10 % or higher, relofting causes the filtration efficiency to decrease significantly. Therefore, the process described in this document is limited to open structures designed for filtration and cannot be used for structures having a high solidity that require good liquid barrier properties.

[0024] While the above processes might provide the possibility to make sheets that are more comfortable to touch, e.g., less stiff or softer, the barrier properties of such materials are usually significantly reduced as a consequence of the softening.

[0025] In active packaging, a sachet or bag which contains active substances is placed in a container in which the articles to be protected are also held. An ideal nonwoven sheet foruse in active packaging should have high water resistance, breathability, and particle barrier properties. An active package is a package which contains an active substance, usually in the form of granules or fine powders, commonly contained in a gas permeable bag or sachet that allows an exchange of gases between the interior of the sachet and the environment for the purpose of protecting an article. Where the article or environment may be wet or create high humidity levels, such as fruits and vegetables, the nonwoven sheet should have a high gas permeability, while also exhibiting low liquid permeability. The gas permeable bag or sachet must also provide a particle barrier to prevent the release of active substances outside of the package.

[0026] It is also preferable that, when used to make sachets or bags, the nonwoven sheet has a sufficiently high level of stiffness to allow fast and efficient forming of the sachets or bags and filling these in the production process, e.g., with active substances, and a sufficiently high level of flexibility or softness to allow folding and pleating. The finished sachet should be sufficiently soft and flexible such that its shape can conform to the shape of its interior contents and it can be inserted into a container with other articles without damaging them. It is further advantageous that the material has good delamination strength and abrasion resistance (high crock value).

[0027] While flash-spun sheets have demonstrated a good variety of desired properties, there has been a trade-off between the desired stiffness, surface robustness, and protection properties. Therefore, there is a need for a flash-spun sheet for use in active packaging which provides improved flexibility and surface robustness, without sacrificing barrier properties and protection.

[0028] SUMMARY OF THE INVENTION

[0029] In one embodiment, the invention is directed to a thermally bonded sheet of nonwoven flash-spun plexifilamentary fibrils, the sheet having

[0030] (a) a basis weight from about 35 g / m2to about 58 g / m2,

[0031] (b) a Gurley Hill porosity of about 20 seconds or less,

[0032] (c) a particle filtration efficiency of about 90 % or more,

[0033] (d) a handle-o-meter stiffness from 0.5 N to about 1.20 N,

[0034] (e) a delamination strength from about 0.1 N to about 1.0 N, and

[0035] (f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0036] In a further embodiment, the invention is directed to a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0037] (i) generating a spin fluid comprising(a) from about 8 to about 12 weight percent of a polymer, and

[0038] (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,

[0039] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (Hi) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0040] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0041] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and

[0042] (vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

[0043] In a further embodiment, the invention is directed to a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0044] (i) generating a spin fluid comprising

[0045] (a) from about 8 to about 12 weight percent of a polymer, and

[0046] (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1, 2-dichloroethylene, trans-1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,

[0047] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (Hi) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0048] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,(v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,

[0049] (vi) embossing the cooled sheet to obtain an embossed sheet, and

[0050] (vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0051] In a further embodiment, the invention is directed to a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0052] (i) generating a spin fluid comprising

[0053] (a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and

[0054] (b) a spin agent comprising one or more hydrocarbons,

[0055] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0056] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0057] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and

[0058] (vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

[0059] In a further embodiment, the invention is directed to a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0060] (i) generating a spin fluid comprising

[0061] (a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and

[0062] (b) a spin agent comprising one or more hydrocarbons,(ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0063] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0064] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,

[0065] (vi) embossing the cooled sheet to obtain an embossed sheet, and

[0066] (vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0067] In a further embodiment, the invention is directed to a protective garment comprising a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene, wherein the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

[0068] BRIEF DESCRIPTION OF THE FIGURES FIGS. 1A to 1C show exemplary illustrations of “point” patterns which can be used in embossing a sheet.

[0069] FIG. 2 shows an exemplary illustration of a “rib” pattern which can be used in embossing a sheet.

[0070] FIG. 3 shows an exemplary illustration of a “linen” pattern which can be used in embossing a sheet.

[0071] FIG. 4A shows a side view of an exemplary illustration of a blunt pin with a hexagonal cross-section which can be used in softening a bonded sheet, FIG. 4B shows a 3D view of that pin, and FIG. 4C shows a top view of that pin.

[0072] FIG. 5A shows a side view of an exemplary illustration of another blunt pin with a shaft having a square cross-section which can be used in softening a bonded sheet, FIG. 5B shows a 3D view of that pin, and FIG. 5C shows a top view of that pin.FIG. 6A shows a side view of an exemplary illustration of a cylindrical blunt pin which can be used in softening a bonded sheet, FIG. 6B shows a top view of that pin, and FIGS. 6C to 6E show 3D views of different alternatives of that pin.

[0073] FIG. 7A shows a side view of an exemplary illustration of another cylindrical blunt pin which can be used in softening a bonded sheet, FIG. 7B shows a top view of that pin, and FIGS. 7C to 7E show 3D views of different alternatives of that pin.

[0074] It will be appreciated that the embossing pattern shown in Figures 1 to 3 and the pin configurations shown in Figures 4 to 7 described herein are given by way of example only, and are not meant to limit the scope of the invention in any way.

[0075] DETAILED DESCRIPTION

[0076] Definitions of Terms and Test methods

[0077] Before addressing details of embodiments, some terms and test methods are defined or clarified. Unless otherwise mentioned, all tests were carried out without preconditioning of the samples. When average values are indicated herein, this refers to the arithmetic average.

[0078] Basis weight is determined according to EN ISO 536 (1996) using a sample size of 100 cm2and is reported in gram per square meter (g / m2). The reported value represents an average of at least 12 individual measurements.

[0079] Gurley Hill porosity (sometimes also referred to as “Gurley Porosity”) is a measure of the permeability of the sheet for gaseous materials. In particular, it is a measure of how long it takes a volume of gas to pass through an area of the sheet wherein a certain pressure gradient exists. Gurley-Hill porosity is determined in accordance with ISO 5636-5 (2003) using a Lorentzen & Wettre Model SE 166 or 516 from Lorentzen & Wettre, Kista, Sweden. The Gurley Hill porosity reported herein is expressed in seconds and represents an average of at least twelve individual measurements. The reported value represents an average of at least 12 individual measurements. The lower the Gurley Hill porosity, the greater the air permeability of the sheet.

[0080] Frazier porosity is a measure of the permeability of the sheet for gaseous materials and is particularly suitable for measuring high permeabilities, for example permeabilities corresponding to Gurley Hill porosities of about 3 seconds or below. In particular, it measures the volume of gas which passes through a defined area of the sheet in a defined time, wherein a certain pressure gradient exists. Frazier porosity is determined in accordance with EN ISO 9237 (1995). The Frazier porosity reported herein is expressed in m3 / m2 / min. The reportedvalues represent an average of at least 12 individual measurements. The higher the Frazier porosity, the greater the air permeability of the sheet.

[0081] Particle filtration efficiency (PFE) is a measure of the relative amount, expressed in percent, of particulates which are retained by a material under given conditions, and particle penetration is a measure of the relative amount, expressed in percent, of particulates which pass through a material under given conditions. Particle filtration efficiency (PFE) is determined by measuring the particle penetration and is calculated as 100 % minus the particle penetration. Herein particle penetration refers to the penetration of particles carried in air and is measured using a TSI 8130 instrument from TSI Incorporated, Shoreview, MN, United States, in accordance with US 42 CF 84 (2004), NIOSH Procedures No. RCT-APR-STP-57, 58, and 59. Airborne sodium chloride particles are generated having a particle size distribution with a count median diameter of 0.075 pm, a mass mean diameter of 0.3 pm, and a geometrical standard deviation of 1.8, with a volumetric air flow rate of 2.3 L / min. This volumetric air flow rate corresponds to a face velocity at the sample surface of 0.4 cm / s, which is representative of typical air flow conditions that the bonded sheet faces when used in a protective garment. In order to achieve a flow rate of 2.3 liter per minute, the control valve of the TSI 8130 is closed so that the air flow is that passing through the downstream photometer only. Measurements are performed with a rise time of 25 seconds and a measurement time of 4 seconds. The particle penetration in percent is determined based on the difference in light intensity measured by upstream and downstream photometers. The pressure drop over the sample is recorded in millimeters of water column (mmH2O). The particle penetration and the particle filtration efficiency values reported herein are averages of at least 12 measurements.

[0082] The particle penetration may also be expressed as the logarithmic reduction value (LRV) based on the following formula

[0083] LRV = -logio(penetration[%] / 100)

[0084] Higher LRV or PFE values represent a higher particle barrier, whereas higher particle penetration values represent a lower particle barrier for the tested material.

[0085] Handle-o-meter stiffness is a measure of the resistance of a sample to being pressed into a 10mm slot by a blade attached to a 1000g penetrator beam that is motor driven. It is measured by ASTM 6828 (2019) - Stiffness of Fabric by Blade / Slot Procedure and is expressed in gram-force (gf), convertible to N by multiplying gf by 9.8067 and dividing by 1000. In accordance with ASTM 6828 (2019), separate measurements are carried out in the machine direction (MD) and in the cross direction (XD) for the material being tested, and the average of the MD and XD values is reported herein A lower Handle-o-meter stiffness value refers to a softer sheet or garment, i.e., a sheet or garment with a higher softness level has a lowerhandle-o-meter stiffness value. The flexural stiffness of a uniform sheet is proportional to the third power of the thickness of the sheet. As sheet thickness generally correlates with basis weight, when comparing different samples, Handle-o-meter stiffness can be normalized to the third power of the basis weight.

[0086] The hydrostatic head is a measure of the resistance of a sheet to penetration by liquid water under a static load. Herein the hydrostatic head is determined based on AATCC 127 (2018). The hydrostatic head is reported in cm of water column. The hydrostatic head is measured on a FX 3000 HydroTester III from TexTest AG, Schwerzenbach, Switzerland. Water in contact with one side of a 102.6 cm2section of a sample is pressurized at a rate of 60 + / - 3 cmH2O / min until three areas of the sample are penetrated by the water. The reported hydrostatic head is the average of at least 6 individual measurements. A higher hydrostatic head value refers to a sheet having a higher resistance to water penetration, that is having a lower water permeability. For a laminated product, the surface of the sheet with the barrier function is the surface in contact with the water for measurement.

[0087] The moisture vapor transmission rate (MVTR) is measured according to EN ISO 12572 (2001), “Hygrothermal performance of building materials and products, Climate C”, using a Gintronic Gravitest 6400 with an ES 420A balance from MRS Seitter, Lenning-Briick, Germany. The following settings are applied. The measurement is performed at 23 °C with a relative humidity of 100 % in the cups, and an air flow above the samples of test material of 2.5 m / s at a relative humidity of 50 %, and using a measurement interval of 30 minutes. A method using multiple layers of the test material is used to eliminate the impacts of the air layer above the water in each cup and of the boundary layer above each sample of test material.

[0088] Five test cups are each filled with water to a height of 15 mm from the top. Two of the test cups are then closed using one layer of test material, one of the test cups is closed using two layers of test material, and the two remaining test cups are closed with three layers of test material. The test is then performed with the five test cups in the same instrument at the same time. The weights of the test cups are monitored until the rate of weight loss from each test cup stabilizes to within + / -5 % during 5 successive measurements. The rate of weight loss is then divided by the upper cross-sectional area of the test cup through which water vapor has diffused to give a water vapor transmission rate per cup (WDD in g / m2 / day), and the total resistance to the water vapor diffusion (Sd, in cm of equivalent air layer thickness) for each cup is calculated using the formula:

[0089] Sd = 2366 / WDDThe Sd values for each cup are then plotted against the number of layers of test material used for that cup and the slope of a line through the points is determined by linear regression. This slope (SDML) represents the incremental increase in water vapor diffusion resistance created by adding one layer of test material. This is then converted back to a moisture vapor transmission rate for one layer of test material by performing the reverse calculation:

[0090] MVTR = 2366 / SDML

[0091] The reported value is for one measurement, which inherently averages the property for ten individual samples of test material. For samples having a moisture vapor transmission rate greater than about 10,000 g / m2 / day it is also possible to apply the procedure above modified as follows. Six test cups are used. Two of the test cups are closed using three layers of test material on each, two of the test cups are closed using six layers of test material on each, and the two remaining test cups are closed using nine layers of test material on each.

[0092] The Ret (resistance to evaporative heat loss through the sample) is a measure of the breathability of a fabric, with lower values corresponding to higher breathability. The Ret is measured according to ISO 11092 (2014) and expressed in m2Pa / W. The Hohenstein Comfort Rating System indicates that breathable fabrics have Ret values between 13 and 30 m2Pa / W, very breathable fabrics have Ret values between 6 and 13 m2Pa / W, and extremely breathable fabrics have Ret values of below 6 m2Pa / W.

[0093] The resistance to chemical permeation is measured according to EN ISO 6529 (2013), Method A "Protective clothing. Protection against chemicals. Determination of resistance of protective clothing materials to permeation by liquids and gases” using 18 wt% sulphuric acid, 30 wt% sulphuric acid, 10 wt% sodium hydroxide, or 40 wt% sodium hydroxide solutions as test liquids, without conditioning of the test specimen. A 112 mm diameter test specimen of the sheet or garment to be tested is clamped between two chambers of a test cell, each chamber having a volume of 100 cm3, such that the test specimen forms a barrier between the two chambers. One chamber, equipped with a conductivity meter, is filled with deionized water and is stirred constantly using a magnetic stirrer. At the start of the test, the other chamber is filled with the test liquid and the conductivity of the deionized water is then recorded every minute for up to 480 minutes. An increase in the conductivity of the deionized water indicates that test liquid has permeated through the test specimen, and the degree of increase in the conductivity can be correlated with a specific amount of permeate. The permeation breakthrough time at a normalized permeation rate of 1.0 pg / cm2 / min is the normalized breakthrough time (BTi.o). A test specimen of a sheet or garment suitable for use in manufacturing chemical protective apparel should have a resistance to chemical permeationof 60 minutes (1 hour) or above, 120 minutes (2 hours) or above, 240 minutes (4 hours) or above, or 480 minutes (8 hours) or above, depending on the usage class of the chemical protective apparel.

[0094] Tensile strength is a measure of the breaking strength of a fabric when subjected to unidirectional stress. Tensile strength is determined by EN ISO 13934-1 (1999) “Textiles -Tensile properties of fabrics - Part 1 : Determination of maximum force and elongation at maximum force using the strip method”, using a 200 mm gauge length between the jaws of the tensilometer and a test speed of 100 mm / min. Results are reported in newtons (per 50 mm sample width). Separate measurements are carried out with tension applied in the machine direction (MD) and in the cross direction (XD) for the material being tested, and the average of the MD and XD values is reported herein. The tensile strength reported herein is an average of at least 12 measurements in the machine direction (MD), and an average of at least 6 measurements in the cross direction (XD). The tensile strength of a uniform sheet is proportional to the thickness of the sheet. As sheet thickness generally correlates with basis weight, when comparing different samples, tensile strength can be normalized to the basis weight.

[0095] Elongation to break (herein also referred to as “elongation”) of a sheet is a measure of the amount a sheet stretches prior to failure (breaking) in a strip tensile test. Herein the elongation is determined based on standard EN ISO 13934-1 (99). The gauge length is 200 mm and the speed of the clamps is 100 mm / min. The reported elongation corresponds to the elongation at the point of maximum force on the stress-strain curve. The elongation is reported in the machine direction (MD) of the sheet, in the cross direction (XD) of the sheet, and as average of the elongation in MD and the elongation in XD.

[0096] Opacity is tested according to ISO 2471 (1998), “Paper and board - Determination of opacity (paper backing) - Diffuse reflectance method”, using a Konica Minolta CR-410 Chroma Meter from Konica Minolta Sensing Europe B.V., Diegem, Belgium. The measurement area is 50 mm in diameter and the illuminated area is 53 mm in diameter, a Konica Minolta CR A44 white reference plate is used as a backing for the specimen to determine its 100% reflectance intensity and a black optical cavity is used as a backing for the specimen during the measurement. The reported opacity is the average of at least 6 individual measurements.

[0097] The delamination strength is measured according to ASTM Standard D2724 (2007) -Standard Test Method for Bond Strength of Bonded, Fused, and Laminated Apparel Fabrics, using a sample width of 25.4 mm, using a gauge length of 60 mm between the jaws of the tensilometer, and a speed of 127 mm / min. The sample is delaminated over a distance of 140 mm and the reported delamination strength is the average of all measurement points betweena distance of 12 mm and 128 mm. The reported delamination strength is reported in N (per 25.4 mm) and is an average of at least 12 measurements in the MD direction.

[0098] The trapezoidal tear strength (also referred to as trapezoid tearing strength) is a measure of the tear resistance of a sheet or garment. The trapezoidal tear strength is measured according to EN ISO 9073-4 (1997) and is expressed in Newton (N), without conditioning of the test specimen. The average trapezoidal tear strength is reported as the average of the trapezoidal tear strength in the machine direction (MD) of the sheet and of the trapezoidal tear strength in the cross direction (XD) of the sheet. The reported trapezoidal tear in either direction is an average of at least 5 measurements. The trapezoidal tear strength of a test specimen tends to increase proportionally with basis weight. Thus, the trapezoidal tear strength can be normalized by dividing it by the actual basis weight.

[0099] The puncture resistance is measured according to ISO 13996: 1999. Five garment test specimens are tested without conditioning, advancing the spike on to and through the specimen at a rate of 100 + / -10 mm / min, and the maximum force (in Newton) needed to penetrate the test specimen is recorded. The reported puncture resistance is the arithmetical mean of the five test specimens.

[0100] Crock is a measure of the abrasion surface resistance of a sample. It is measured using a Crockmeter tester, Crockmaster Model 680 from PPT Group Corp, according to a modified method based on AATCC TM-8-1985. A piece of silicon carbide paper is taped to the base of the Crockmeter, directly under the full movement of the rubber foot. The carbide paper serves to prevent the sample from moving. A rubber disk, measuring %” diameter is fastened to the swing bar of the Crockmeter. The disk is a Tabor CS-10 Weardisc® abradant (Part Number: 131434). The swing bar handle is turned so that the rubber foot traverses back and forth across the surface of the sample, at a rotation speed of 60 cycles per minute. One cycle represents a movement back and forth. When the first surface fiber is disturbed (i.e., becomes visibly raised above the surrounding surface), the test is stopped and the number of cycles to that point is determined from the counter on the instrument. The reported abrasion surface resistance is the average of at least 6 individual measurements per side of a sample.

[0101] The abrasion resistance is measured in accordance with ISO 12947-2:2016 in the inverted mode, using abrasive paper as specified in ISO / DIS 16602-2:2025. The number of rubs is set to a defined value of 10, 40, 100, 400, 1000 or 2000 according to the performance classification in ISO / DIS 16602-2:2025. Four test specimens are tested, with a downward pressure of 9 kPa exposing the outside of the garment to the abrasive paper. The abrasion resistance (number of rubs) is determined by exposing each of the four abraded test specimens to the measurement of hydrostatic head method according to ISO 811 using a rate of increase in pressure of 10cm H2O / min. The reported results correspond to the highest number of rubs at which the average hydrostatic head is still above 200 mm.The seam strength is measured according to EN ISO 13935-22014. At least three test specimens of each type of seam construction on the garment are tested without conditioning. The arithmetic mean of each set of test specimens is calculated and the reported result is the average value (in Newton) of the weakest seam type tested regardless of whether the test specimen broke in the material or in the seam.

[0102] The Type 5, inward leakage of aerosols of fine particles into suits, testing is performed according to EN ISO 13982-1 :2004+A1:2010 and EN ISO 13982-2:2004, on a garment with taped cuffs, taped ankles, a taped hood, and a taped zipper flap. The total inward leakage (%) is the average based on testing 10 test specimens of each garment.

[0103] The hardness of back-up roll surface materials is determined based on DIN ISO 7619-1 (2010) - Rubber, vulcanized or thermoplastic - Determination of indentation hardness -Part 1 : Durometer method (Shore hardness). The hardness is reported in Shore A.

[0104] Thickness of the sheet is measured according to standard EN ISO 534 (2005). The sheet is a measured using a probe having a circular area of 2 cm2with an applied pressure of 50 kPa. The time to lower the probe is 2 seconds and the hold time is 4 seconds. The reported value represents an average of at least 100 individual measurements.

[0105] BET surface area is measured by the BET nitrogen absorption method of S. Brunauer, P. H. Emmett and E. Teller, J. Am. Chem. Soc., V. 60 p 309-319 (1938) based on 5 equidistant relative pressures between 0.1 to 0.25 and is reported as m2 / g. The samples measured have a total surface area above 2 m2. Performance of the equipment is verified by using a standard aluminum oxide sample (3P-SRF586) having a BET surface area of 5.86 + / - 0.23 m2 / gram supplied by 3P Instruments GmbH & Co, Odelzhausen, Germany. Before measurement, the samples are dried for at least 2 hours at a temperature of 60 °C under vacuum. The BET surface area reported herein is based on 1 or 2 measurements.

[0106] Melting point is determined by differential scanning calorimetry, following the guidance provided in ASTM D3418 (Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry) and ASTM Standard F2625 (Standard Test Method for Measurement of Enthalpy of Fusion, Percent Crystallinity and Melting Point of Ultra-High-Molecular weight polyethylene by means of differential scanning calorimetry). For polyethylene, heating and cooling is performed under inert gas at a rate of 10 °C / minute, heating the sample first from room temperature to 210 °C, then cooling the sample back to room temperature and subsequently heating the sample a second time to 210 °C. The melting point reported herein is the peak temperature of the endotherm of the second heating cycle. For polypropylene the same procedure applies -where the maximum temperature is 230 °C.

[0107] The melt flow rate is determined according to the method described in ISO 1133 (Plastics - Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate(MVR) of thermoplastics). The melt flow rate for polyethylene is determined at a temperature of 190 °C and using a mass of 2160 grams or 21 ,600 grams. The melt flow rate for polypropylene is determined at a temperature of 230 °C and using a mass of 2160 grams (2.16 kg). The melt flow rates of other polyolefins are performed at different temperatures as specified in ISO 1133.

[0108] Density is determined according to the method described in ISO 1183 (Plastics -Methods for determining the density of non-cellular plastics).

[0109] The term “polymer” is intended to embrace, without limitation, homopolymers, copolymers (such as for example, block, graft, random, and alternating copolymers), terpolymers, etc., and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries.

[0110] The term “polyethylene” is intended to embrace not only homopolymers of ethylene, but also copolymers and terpolymers wherein at least 85 % of the recurring units are ethylene units, and the comonomer unit is, for example, propylene, butylene, hexene or octene. One useful polyethylene is a high-density polyethylene that has a melting point from about 123 °C to about 140 °C, a density of 0.94 to 0.98 grams per cubic centimeter, and a melt flow rate (ISO 1133 190 °C / 2160 grams) from 0.05 g / 10min to 30 g / 10min, preferably less than 4 g / 10min, and / or a melt flow rate (ISO 1133, 190 °C / 21 ,600 grams) from 1 g / 10min to 15 g / 10min. The polyethylene may contain up to about 10 weight percent or up to about 5 weight percent of other polymers, such as other polyolefins, for example polypropylene.

[0111] The term “polypropylene” is intended to embrace not only homopolymers of propylene but also copolymers and terpolymers where at least 85 % of the recurring units are propylene units. Furthermore, unless otherwise specifically limited, the term “polypropylene” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries. The polypropylene may contain up to about 10 weight percent or up to about 5 weight percent of other polymers, such as other polyolefins, for example polyethylene.

[0112] The term “polymer type” refers to the chemical class into which the polymer falls, for example, polyethylene, polypropylene, etc.

[0113] The term “plexifilamentary” refers to a three-dimensional integral network or web of a multitude of thin, ribbon-like, fibrils of random length and a median fibril width of less than about 25 microns. In plexifilamentary structures, the fibrils are generally coextensively aligned with the longitudinal axis of the structure, and they intermittently unite and separate at irregular intervals in various places throughout the length, width, and thickness of the structure to form a continuous three-dimensional network or web.The term “garment” refers to a piece of clothing to be worn. The term “protective garment” is intended to referto a single article of protective clothing, worn to provide protection to the wearer’s skin against exposure to the environment, which covers or replaces personal garment(s). The term “chemical protective garment” is intended to refer to a single article of protective clothing, worn to provide protection to the wearer’s skin against exposure to or contact with chemicals, which covers or replaces personal garment(s).

[0114] The terms “inside of the garment,” “inside of the protective garment,” and “inside of the chemical protective garment” are intended to referto the side of the garment facing the wearer. The terms “outside of the garment,” “outside of the protective garment,” or “outside of the chemical protective garment” are intended to refer to the opposite side of the garment facing the environment.

[0115] The term “1 ,2-dichloroethylene” (1,2-DCE) is intended to embrace, without limitation, the cis-isomer, trans-isomer, or any combination or mixture of both isomers in any ratio.

[0116] The term “1H,2H-octafluorocyclopentane” is intended to embrace, without limitation, the cis-isomer, trans-isomer, or any combination or mixture of both isomers in any ratio.

[0117] The terms “spin agent” or “spin agent composition” refers to a composition comprising one or more solvents and any additives that are used to initially dissolve the polymer(s) to form the spin fluid. Suitable additives include stabilizers, such as antioxidants or acid scavengers.

[0118] The term “spin fluid” refers to a solution for spinning in a flash spinning process comprising a polymer and a spin agent. The solution may also include one or more additives.

[0119] The term “cloud point pressure” refers to the pressure at which, at constant temperature, a clear single phase spin fluid transitions from a clear solution to a cloudy, two-phase dispersion. At the cloud point pressure, a clear spin fluid becomes turbid.

[0120] Atmospheric pressure means 101.325 kPa. Essentially atmospheric pressure means 101.325 kPa ± 5 %.

[0121] As used herein, the singular forms "a," "an," and "the" include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. When a range of values is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. All ranges are inclusive and combinable.

[0122] Bonded Sheet of Nonwoven Flash-spun Plexifilamentary Fibrils

[0123] Provided herein is a thermally bonded sheet of nonwoven flash-spun plexifilamentary fibrils, the sheet having(a) a basis weight from about 35 g / m2to about 58 g / m2,

[0124] (b) a Gurley Hill porosity of about 20 seconds or less,

[0125] (c) a particle filtration efficiency of about 90 % or more,

[0126] (d) a handle-o-meter stiffness from 0.5 N to about 1.20 N,

[0127] (e) a delamination strength from about 0.1 N to about 1.0 N, and

[0128] (f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0129] The thermally bonded sheet described herein exhibits a desired combination of moderate basis weight, low Gurley Hill porosity, high particle filtration efficiency, moderate handle-o-meter stiffness, high delamination strength, and a high MVTR.

[0130] In some embodiments, the bonded sheet has a basis weight from about 39 g / m2to about 58 g / m2, in other embodiments, the bonded sheet has a basis weight from about 40 g / m2to about 49 g / m2, in other embodiments, the bonded sheet has a basis weight from about 40 g / m2to about 44 g / m2, and in other embodiments, the bonded sheet has a basis weight from about 44 g / m2to about 49 g / m2.

[0131] In some embodiments, the bonded sheet has a Gurley Hill porosity of about 15 seconds or less, in other embodiments, the bonded sheet has a Gurley Hill porosity of about 10 seconds or less, and in other embodiments, the bonded sheet has a Gurley Hill porosity of about 5 seconds or less. In some embodiments, the bonded sheet has a Gurley Hill porosity from about 2 seconds to about 20 seconds, in other embodiments, the bonded sheet has a Gurley Hill porosity from about 2 seconds to about 15 seconds, in other embodiments, the bonded sheet has a Gurley Hill porosity from about 2 seconds to about 10 seconds, and in other embodiments, the bonded sheet has a Gurley Hill porosity from about 2 seconds to about 5 seconds. In some embodiments, the bonded sheet has a Gurley Hill porosity from about 10 seconds to about 20 seconds.

[0132] In some embodiments, the bonded sheet has a Frazier porosity from about 0.3 m3 / m2 / min to about 3 m3 / m2 / min, in other embodiments, the bonded sheet has a Frazier porosity from about 0.3 m3 / m2 / min to about 1.5 m3 / m2 / min.

[0133] In some embodiments, the bonded sheet has a particle filtration efficiency of about 93 % or more, in other embodiments, the bonded sheet has a particle filtration efficiency of about 95 % or more, in other embodiments, the bonded sheet has a particle filtration efficiency of about 97 % or more, and in other embodiments, the bonded sheet has a particle filtration efficiency of about 98 % or more. In some embodiments, the bonded sheet has a particle filtration efficiency from about 90.0 % to about 99.9 %, in other embodiments, the bonded sheet has a particle filtration efficiency from about 93.0 % to about 99.9 %, in other embodiments, the bonded sheet has a particle filtration efficiency from about 95.0 % to about99.9 % or about 95.0 % to about 99.5 %, in other embodiments, the bonded sheet has a particle filtration efficiency from about 97.0 % to about 99.9 % or about 97.0 % to about 99.0 %, and in other embodiments, the bonded sheet has a particle filtration efficiency from about 98.0 % to about 99.9 %.

[0134] In some embodiments, the bonded sheet has a handle-o-meter stiffness from about 0.5 N to about 1.2 N, in other embodiments, the bonded sheet has a handle-o-meter stiffness from about 0.5 N to about 1.0 N, in other embodiments, the bonded sheet has a handle-o-meter stiffness from about 0.6 N to about 1.0 N, and in other embodiments, the bonded sheet has a handle-o-meter stiffness from about 0.6 N to about 0.8 N, from 0.5 N to about 1.0 N, or from 0.5 N to about 0.8 N. In some embodiments, the bonded sheet has a handle-o-meter stiffness from about 0.8 N to about 1.2 N, and in other embodiments, the bonded sheet has a handle-o-meter stiffness from about 1.0 N to about 1.2 N.

[0135] In some embodiments, the bonded sheet has a delamination strength from about 0.2 N to about 0.7 N, in other embodiments, the bonded sheet has a delamination strength from about 0.2 N to about 0.6 N, in other embodiments, the bonded sheet has a delamination strength from about 0.2 N to about 0.5 N, and in other embodiments, the bonded sheet has a delamination strength from about 0.2 N to about 0.4 N. In some embodiments, the bonded sheet has a delamination strength from about 0.3 N to about 0.6 N, and in other embodiments, the bonded sheet has a delamination strength from about 0.4 N to about 0.6 N.

[0136] In some embodiments, the bonded sheet has an average tensile strength from about 70 N to about 180 N, in other embodiments, the bonded sheet has average tensile strength from about 70 N to about 160 N, in other embodiments, the bonded sheet has average tensile strength from about 90 N to about 160 N, and in other embodiments, the bonded sheet has average tensile strength from about 70 N to about 130 N. In some embodiments, the bonded sheet has an average tensile strength from about 130 N to about 160 N.

[0137] In some embodiments, the bonded sheet has an average tensile strength, normalized to basis weight, from about 1.5 N / (g / m2) to about 4.0 N / (g / m2), in other embodiments the bonded sheet has an average tensile strength, normalized to basis weight, from about 1.5 N / (g / m2) to about 3.6 N / (g / m2), and the bonded sheet has an average tensile strength, normalized to basis weight, from about 1.5 N / (g / m2) to about 2.7 N / (g / m2). In some embodiments, the bonded sheet has an average tensile strength, normalized to basis weight, from about 2.7 N / (g / m2) to about 3.6 N / (g / m2).

[0138] In some embodiments, the bonded sheet has a handle-o-meter stiffness, normalized to (basis weight)3, of about 0.0004 N / (g / m2)3or above, in other embodiments the bonded sheet has a handle-o-meter stiffness, normalized to (basis weight)3, of about 0.0005 N / (g / m2)3or above, and in other embodiments the bonded sheet has a handle-o-meter stiffness, normalized to (basis weight)3, of about 0.0006 N / (g / m2)3or above. In some embodiments, thebonded sheet has a handle-o-meter stiffness, normalized to (basis weight)3, from about 0.0004 N / (g / m2)3to about 0.0015 N / (g / m2)3, in other embodiments, the bonded sheet has a handle-o-meter stiffness, normalized to (basis weight)3, from about 0.0005 N / (g / m2)3to about 0.0014 N / (g / m2)3, and in other embodiments, the bonded sheet has a handle-o-meter stiffness, normalized to (basis weight)3, from about 0.0006 N / (g / m2)3to about 0.0012 N / (g / m2)3.

[0139] In some embodiments, the bonded sheet has an abrasion surface resistance with a crock from 10, or 20, or 30 or 40 cycles to 100 cycles, in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 10, or 20, or 30 cycles to 80 cycles, in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 10, or 20, or 30 cycles to 60 cycles, in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 10, or 20, or 30 cycles to 40 cycles, and in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 10 to 30 cycles. In some embodiments, the bonded sheet has an abrasion surface resistance with a crock from 20 to 100 cycles, in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 20 to 80 cycles, in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 20 to 60 cycles, in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 20 to 40 cycles, and in other embodiments the bonded sheet has an abrasion surface resistance with a crock from 20 to 30 cycles.

[0140] In some embodiments, the bonded sheet has a MVTR from about 8,000 g / m2 / day to about 30,000 g / m2 / day, in other embodiments, the bonded sheet has a MVTR from about 10,000 g / m2 / day to about 28,000 g / m2 / day, and in other embodiments, the bonded sheet has a MVTR from about 10,000 g / m2 / day to about 26,000 g / m2 / day. In some embodiments, the bonded sheet has a MVTR from about 10,000 g / m2 / day to about 18,000 g / m2 / day, in other embodiments, the bonded sheet has a MVTR from about 10,000 g / m2 / day to about 16,000 g / m2 / day, and in other embodiments, the bonded sheet has a MVTR from about 10,000 g / m2 / day to about 14,000 g / m2 / day. In some embodiments, the bonded sheet has a MVTR from about 12,000 g / m2 / day to about 30,000 g / m2 / day, in other embodiments, the bonded sheet has a MVTR from about 14,000 g / m2 / day to about 28,000 g / m2 / day, and in other embodiments, the bonded sheet has a MVTR from about 16,000 g / m2 / day to about 28,000 g / m2 / day.

[0141] In some embodiments, the bonded sheet has a Ret from about 2 m2Pa / W to about 10 m2Pa / W, in other embodiments, the bonded sheet has a Ret from about 2 m2Pa / W to about 5 m2Pa / W, and in other embodiments, the bonded sheet has a Ret from about 2 m2Pa / W to about 4 m2Pa / W. In some embodiments, the bonded sheet has a Ret from about 3 m2Pa / W to about 8 m2Pa / W, in other embodiments, the bonded sheet has a Ret from about 3 m2Pa / W to about 6 m2Pa / W or from about 3 m2Pa / W to about 5 m2Pa / W, and in other embodiments, thebonded sheet has a Ret from about 4 m2Pa / Wto about 6 m2Pa / W. In some embodiments, the bonded sheet has a Ret from about 4 m2Pa / W to about 10 m2Pa / W, in other embodiments, the bonded sheet has a Ret from about 6 m2Pa / W to about 10 m2Pa / W.

[0142] In some embodiments, the bonded sheet has a thickness from about 150 m to about 220 pm, and in other embodiments, the bonded sheet has a thickness from about 160 pm to about 220 pm. In some embodiments, the bonded sheet has a thickness from about 150 pm to about 200 pm, and in other embodiments, the bonded sheet has a thickness from about 160 pm to about 200 pm.

[0143] In some embodiments, the sheet has a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 10 wt% NaOH or 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, in other embodiments, the sheet has a resistance to chemical permeation, BT10, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0144] In some embodiments, the sheet has a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH or 40 wt% NaOH and against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0145] In some embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 6 % to about 19 %, in other embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 6 % to about 14 %, in other embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %, in other embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 11 %. and in other embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %. In some embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 10 % to about 30 %, in other embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 15 % to about 30 %, and in other embodiments, the bonded sheet has an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 20 % to about 30 %.In some embodiments, the bonded sheet has an average elongation from about 6 % to about 19 %, in other embodiments, the bonded sheet has an average elongation from about 6 % to about 14 %, in other embodiments, the bonded sheet has an average elongation from about 7 % to about 12 %, in other embodiments, the bonded sheet has an average elongation from about 7 % to about 11 %. and in other embodiments, the bonded sheet has an average elongation from about 7 % to about 10 %. In some embodiments, the bonded sheet has an average elongation from about 10 % to about 30 %, in other embodiments, the bonded sheet has an average elongation from about 15 % to about 30 %, and in other embodiments, the bonded sheet has an average elongation from about 20 % to about 30 %. The average elongation is calculated as (elongation in MD + elongation in XD) divided by two.

[0146] In some embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.2 to about 5, in other embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.33 to about 3, and in other embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.5 to about 2. In some embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.6 to about 1.5, in other embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.7 to about 1.4, in other embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.8 to about 1.25, and in other embodiments, the bonded sheet has a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.9 to about 1.1.

[0147] In some embodiments, the bonded sheet has a hydrostatic head from about 100 cmH2O to about 200 cmH2O, in other embodiments, the bonded sheet has a hydrostatic head from about 110 cmH2O to about 200 cmH2O, in other embodiments, the bonded sheet has a hydrostatic head from about 110 cmH2O to about 180 cmH2O, and in other embodiments, the bonded sheet has a hydrostatic head from about 110 cmH2O to about 160 cmH2O. In some embodiments, the bonded sheet has a hydrostatic head from about 120 cmH2O to about 180 cmH2O, in other embodiments, the bonded sheet has a hydrostatic head from about 120 cmH2O to about 160 cmH2O, and in other embodiments, the bonded sheet has a hydrostatic head from about 140 cmH2O to about 180 cmH2O.In some embodiments, the bonded sheet has an average trapezoidal tear strength from about 10 N to about 50 N, from about 10 N to about 40 N, from about 10 N to about 30 N, from about 15 N to about 30 N, or from about 20 N to about 30 N.

[0148] In some embodiments, the bonded sheet has an average puncture resistance from about 10 N to about 30 N, from about 10 N to about 25 N, or from about 12 N to about 25 N.

[0149] In some embodiments, the bonded sheet has an opacity of about 90 % or more, of about 93 % or more, of about 95 % or more, or of about 97 % or more. In some embodiments, the bonded sheet has an opacity from about 90 % to about 99 %, from 90 % about to about 97 %, from about 93 % to about 97 %, from about 95 % to about 99 %, or from about 95 % to about 97 %.

[0150] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a polyolefin. In some embodiments, the polyolefin is selected from polyethylene (PE), polypropylene (PP), and blends / mixtures thereof. Particularly preferred polyolefins are polyethylene (PE), in particular high-density polyethylene (HDPE), and blends / mixtures of high-density polyethylene (HDPE) with low-density polyethylene (LDPE), in particular with linear low-density polyethylene (LLDPE). In some embodiments, the polyolefin is a high-density polyethylene (HDPE).

[0151] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or O.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, and a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 28,000 g / m2 / day.

[0152] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and an average tensile strength from about 70 N to about 180 N.

[0153] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a Moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about28,000 g / m2 / day, and an average tensile strength, normalized to basis weight, from about 1.5 N / (g / m2) to about 3.6 N / (g / m2).

[0154] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and an abrasion surface resistance with a crock from 10 to about 100 cycles.

[0155] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, and an abrasion surface resistance with a crock from 10 to 100 cycles.

[0156] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %, and an abrasion surface resistance with a crock from 10 to 100 cycles.

[0157] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %, and an abrasion surface resistance with a crock from 10 to 100 cycles.In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Frazier air permeability from about 0.3 m3 / m2 / min to about 3 m3 / m2 / min), a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %, and an abrasion surface resistance with a crock from 10 to 100 cycles.

[0158] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or O.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %.

[0159] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0160] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %.

[0161] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0162] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day.

[0163] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0164] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.20 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %.

[0165] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, andan elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0166] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 39 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0167] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 39 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0168] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day.

[0169] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and a thickness from about 150 pm to about 210 pm.

[0170] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity of about 20 seconds or less, a particle filtration

[0171] T1efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.1 N to about 1.0 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, an average puncture resistance from about 10 N to about 25 N, a resistance to chemical permeation, BT-i o, measured according to ISO 6529 against 10 wt% NaOH of 120 min or above, or of 240 min or above, and a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 18 wt% H2SO4 of 120 min or above, or of 240 min or above.

[0172] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity of about 20 seconds or less, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N or 0.5 N to about 1.2 N, a delamination strength from about 0.1 N to about 1.0 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, an average trapezoidal tear strength from about 10 N to about 40 N, a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH of 120 min or above, or of 240 min or above, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% H2SO4of 120 min or above, or of 240 min or above.

[0173] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day.

[0174] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a Ret from about 2 m2Pa / W to about 8 m2Pa / W.

[0175] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vaportransmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and a thickness from about 150 m to about 210 pm.

[0176] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / Wto about 8 m2Pa / W, and a thickness from about 150 pm to about 210 pm.

[0177] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0178] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0179] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0180] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N toabout 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0181] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0182] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0183] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0184] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), of from about 7 % to about 12 %.

[0185] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), of from about 7 % to about 12 %.

[0186] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0187] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0188] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0189] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day or about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0190] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0191] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0192] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0193] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtrationefficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, a thickness from about 150 m to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0194] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0195] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0196] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0197] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0198] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0199] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0200] In some embodiments, the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0201] Applicant has found that the bonded sheets as described herein surprisingly have a very good balance of barrier properties, breathability, and delamination strength, combined with a moderate degree of stiffness which makes them very suitable for use in packaging, including, but not limited to, active packaging, covers for equipment including vehicles (e.g.car covers), cargo covers, mattress covers, industrial bags, consumer bags, medical packages, and further applications.

[0202] Unexpectedly, the process as described herein enables softening of a whole surface bonded sheet. In a whole surface area bonded sheet, the surface fibers become very strongly bonded with low fiber mobility, so it would not have been anticipated that a whole surface bonded sheet could respond to a softening process as the Applicant has observed.

[0203] Preparation of Bonded Sheet of Nonwoven Flash-spun Plexifilamentary Fibrils of Polymer

[0204] In a further embodiment, there is provided a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0205] (i) generating a spin fluid comprising

[0206] (a) from about 8 to about 12 weight percent of a polymer, and

[0207] (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,

[0208] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (Hi) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0209] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0210] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and

[0211] (vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.In a further embodiment, there is provided a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0212] (i) generating a spin fluid comprising

[0213] (a) from about 8 to about 12 weight percent of a polymer, and

[0214] (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,

[0215] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (Hi) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0216] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0217] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,

[0218] (vi) embossing the cooled sheet to obtain an embossed sheet, and

[0219] (vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0220] In a further embodiment, there is provided a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0221] (i) generating a spin fluid comprising

[0222] (a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and

[0223] (b) a spin agent comprising one or more hydrocarbons,

[0224] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (Hi) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0225] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and

[0226] (vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

[0227] In still a further embodiment, there is provided a process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0228] (i) generating a spin fluid comprising

[0229] (a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and

[0230] (b) a spin agent comprising one or more hydrocarbons,

[0231] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0232] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0233] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,

[0234] (vi) embossing the cooled sheet to obtain an embossed sheet, and

[0235] (vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.Flash-Spinning, Collecting, and Consolidating

[0236] Flash-spinning is a method for producing fibrils having a unique plexifilamentary structure. It involves preparing a solution of a fibril-forming polymer in a spin agent (the spin fluid) at a pressure above the vapor pressure of the spin agent and at a temperature above the normal boiling point of the spin agent and releasing that spin fluid into a zone of substantially lower temperature and pressure such that the spin agent flash evaporates and the polymer solidifies in the form of plexifilamentary fibrils. Suitable flash spinning processes and equipment which can be used herein are described in US 3,081,519, US 3,227,794, US 3,860,369, and US 7,744,989.

[0237] The formed plexifilamentary fibrils of polymer are discharged from each spin orifice, and the shape of these plexifilamentary fibrils of polymer may be modified by any methods known in the art. In some embodiments, the plexifilamentary fibrils of polymer discharged from each spin orifice may be modified by passing into a shroud such as described on US 3,387,326, in other embodiments by passing into a slotted outlet such as described in US 3,467,744 or US 5,788,993, and in other embodiments by passing into a slot fan jet as described in US 8,114,325. In some embodiments, streams of fibrils from multiple orifices may exit via a common slot as described in US 3,564,088.

[0238] Sheets comprising plexifilamentary fibrils of polymer can be formed by any method known in the art. In some embodiments, the stream of fibrils discharged from each spin orifice is directed towards a deflector device which alternately directs the stream of fibrils to the left and right onto a moving collecting device such that the fibrils accumulate in the form of a sheet, formed from fibrils oriented in an overlapping, multi-directional configuration. Deflection of the stream of fibrils may be achieved by any suitable means known in the art, including, but not limited to, those described in US 3,277,526 and US 3,387,326, US 3,169,899, US 3,497,918, US 3,593,074, US 3,851 ,023 and US 3,860,369, US 4,148,595, US 5,045,258, US 5,643,524, US 5,731 ,011 , US 5,750,152 and WO 92 / 20511 A1. The stream of fibrils may also be laid down to form a sheet without deflection as described in US 5,788,993 and US 8, 114,325. The method of forming a sheet may further utilize structures in the spin cell such as those described in US 5,123,983, US 5,296,172, and WO 92 / 20511 A1.

[0239] In some embodiments, the streams of fibrils are discharged from spin orifices located on a rotating support, and the fibrils are collected on a collecting belt which surrounds the rotating arrangement circumferentially as described in US 7,118,698, US 7,621 ,731, US 7,786,034, and US 7,998,388.

[0240] The sheet formed by flash-spinning as described herein may be consolidated by applying a small amount of pressure to the sheet. In some embodiments, the sheet may be passed under a roller which applies pressure to the sheet to form a lightly consolidated sheet.A broad range of different polymers and blends / mixtures thereof can be used in the process described herein. In some embodiments, the polymer is selected from polyolefins. In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), and blends / mixtures thereof. Particularly preferred polyolefins are polyethylene (PE), in particular high-density polyethylene (HDPE), and blends / mixtures of high-density polyethylene (HDPE) and low-density polyethylene (LDPE), in particular linear low-density polyethylene (LLDPE). In some embodiments, the polyolefin comprises at least 80 weight percent of high-density polyethylene (HDPE), based on the total amount of polymer. In other embodiments, the polyolefin comprises at least 90 weight percent of high-density polyethylene (HDPE), based on the total amount of polymer, and in other embodiments, the polyolefin comprises at least 95 weight percent of high-density polyethylene (HDPE), based on the total amount of polymer.

[0241] Process with the mixture of chlorine- and fluorine-containing solvents

[0242] The spin agent may include a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, or a mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent. In some embodiments, the spin fluid comprises the polymer in an amount from about 8.0 to about 12.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the polymer in an amount from about 8.0 to about 11.5 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the polymer in an amount from about 8.0 to about 11.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the polymer in an amount from about 8.0 to about 10.5 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the polymer in an amount from about 8.0 to about 10.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the polymer in an amount from about 8.5 to about 11.5 weight percent, based on the total amount of the spin fluid, and in other embodiments, the spin fluid comprises the polymer in an amount from about 9.0 to about 11.0 weight percent, based on the total amount of the spin fluid.

[0243] In some embodiments, the spin fluid comprises the spin agent in an amount from about 88.0 to about 92.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the spin agent in an amount from about 88.5 to about 92.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the spin agent in an amount from about 89.0 to about 92.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the spin agent in an amount from about 89.5 to about 92.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the spin agent in anamount from about 90.0 to about 92.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the spin agent in an amount from about 88.5 to about 91.5 weight percent, based on the total amount of the spin fluid, and in other embodiments, the spin fluid comprises the spin agent in an amount from about 89.0 to about 91.0 weight percent, based on the total amount of the spin fluid.

[0244] In some embodiments, the flash-spinning is performed at a temperature from about 195 °C to about 230 °C, and in other embodiments, from about 200 °C to about 220 °C, in other embodiments, from about 205 °C to about 220 °C, and in other embodiments, from about 210 °C to about 220 °C.

[0245] In some embodiments, the spin agent comprises a chlorine-containing solvent, selected from dichloromethane, cis-1 ,2-dichloroethylene, trans-1 ,2-dichloroethylene or a mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent. In some embodiments, the spin agent comprises a chlorine-containing solvent, selected from dichloromethane, cis-1 ,2-dichloroethylene, trans-1 ,2-dichloroethylene, or a mixture of cis-1 ,2-dichloroethylene and trans-1,2-dichloroethylene, in combination with a fluorine-containing solvent which is a linear hydrofluorocarbon having three to six carbon atoms, a cyclic hydrofluorocarbon having four to five carbon atoms, a perfluorocarbon having five to six carbon atoms, ora hydrofluoroether. In some embodiments, the linear hydrofluorocarbons having three to six carbon atoms of the spin agent are 1 ,1 ,1 ,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane. In some embodiments, the cyclic hydrofluorocarbons having four to five carbon atoms of the spin agent are cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1,1,2,2,3,3-hexafluorocyclopentane. In some embodiments, the hydrofluoroethers of the spin agent are 1 -methoxynonafluorobutane or 1-ethoxynonafluorobutane.

[0246] In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) dichloromethane and (2) 1 ,1 ,1 ,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent dichloromethane and (2) from about 15 to about 30 weight percent 1,1,1,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane, and in other embodiments, (1) from about 75 to about 85 weight percent dichloromethane and (2) from about 15 to about 25 weight percent 1,1,1,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane.In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) dichloromethane and (2) cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3-hexafluorocyclopentane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 80 weight percent dichloromethane and (2) from about 20 to about 35 weight percent cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3-hexafluorocyclopentane, and in other embodiments, (1) from about 65 to about 75 weight percent dichloromethane and (2) from about 25 to about 35 weight percent cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1,1,2,2,3,3-hexafluorocyclopentane.

[0247] In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) 1,2-dichloroethylene and (2) 1,1,1,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent 1,2-dichloroethylene and (2) from about 15 to about 30 weight percent 1,1,1,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane, and in other embodiments, (1) from about 70 to about 80 weight percent 1,2-dichloroethylene and (2) from about 20 to about 30 weight percent 1,1,1,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0248] In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) 1,2-dichloroethylene and (2) cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3-hexafluorocyclopentane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 80 weight percent 1,2-dichloroethylene and (2) from about 20 to about 35 weight percent cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane or 1, 1,2, 2,3,3-hexafluorocyclopentane, and in other embodiments, (1) from about 65 to about 75 weight percent 1,2-dichloroethylene and (2) from about 20 to about 30 weight percent cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1 ,1 ,2,2, 3, 3-hexafluorocyclopentane.

[0249] In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) trans-1,2-dichloroethylene and (2) 1 ,1 ,1 ,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent trans-1 ,2-dichloroethylene and (2) from about 15 to about 30 weight percent 1 ,1 ,1 ,3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane, and in other embodiments, (1) from about 70 to about 80 weight percent trans- 1,2-dichloroethylene and (2) from about 20 to about 30 weight percent 1,1, 1,3, 3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0250] In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) trans- 1,2-dichloroethylene and (2) cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3-hexafluorocyclopentane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 80 weight percent trans-1, 2-dichloroethylene and (2) from about 20 to about 35 weight percent cis-1H,2H-octafluorocyclopentane, trans-1 H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1 H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1,1, 2, 2, 3, 3-hexafluorocyclopentane, and in other embodiments, (1) from about 65 to about 75 weight percent trans-1 ,2-dichloroethylene and (2) from about 20 to about 30 weight percent cis-1H,2H-octafluorocyclopentane, trans-1 H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1 H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3-hexafluorocyclopentane.

[0251] In some embodiments, the spin agent comprises, consists essentially, or consists of a mixture of (1) dichloromethane and (2) 1 -methoxynonafluorobutane or 1-ethoxynonafluorobutane. In some embodiments, the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent dichloromethane and (2) from about 15 to about 30 weight percent 1 -methoxynonafluorobutane or 1-ethoxynonafluorobutane, and in other embodiments, (1) from about 70 to about 80 weight percent dichloromethane and (2) from about 20 to about 30 weight percent 1-methoxynonafluorobutane or 1 -ethoxynonafluorobutane.The spin fluid may include additives, such as antioxidants or acid scavengers in minor amounts. In some embodiments, the spin fluid comprises additives in an amount of about 1.5 weight percent or less of the total amount of the spin fluid, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin fluid.

[0252] In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 195 °C to about 230 °C using a spin fluid comprising about 8.0 to about 12.0 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 200 °C to about 220 °C using a spin fluid comprising about 8.0 to about 12.0 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 205 °C to about 230 °C using a spin fluid comprising about 8.0 to about 11.5 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 210 °C to about 220 °C using a spin fluid comprising about 8.0 to about 11.5 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 205 °C to about 230 °C using a spin fluid comprising about 8.0 to about 11.0 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 210 °C to about 220 °C using a spin fluid comprising about 8.0 to about 11.0 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 205 °C to about 230 °C using a spin fluid comprising about 8.0 to about 10.5 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 210 °C to about 220 °C using a spin fluid comprising about 8.0 to about 10.5 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 205 °C to about 230 °C using a spin fluid comprising about 8.0 to about 10.0 weight percent polymer. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 210 °C to about 220 °C using a spin fluid comprising about 8.0 to about 10.0 weight percent polymer.

[0253] Process with one or more hydrocarbons as spin agent

[0254] The spin agent may include one or more hydrocarbons. In some embodiments, the spin fluid comprises the polymer in an amount of from about 12.0 to about 18.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the polymer in an amount from about 14.0 to about 18.0 weight percent, based on the total amount of the spin fluid, and in other embodiments, the spin fluid comprises the polymer in an amount from about 15.0 to about 17.0 weight percent, based on the total amount of the spin fluid.

[0255] In some embodiments, the spin fluid comprises the spin agent in an amount of from about 82.0 to about 88.0 weight percent, based on the total amount of the spin fluid, in other embodiments, the spin fluid comprises the spin agent in an amount from about 82.0 to about86.0 weight percent, based on the total amount of the spin fluid, and in other embodiments, the spin fluid comprises the spin agent in an amount from about 83.0 to about 85.0 weight percent, based on the total amount of the spin fluid.

[0256] In some embodiments, the flash-spinning is performed at a temperature of 195 °C or above, in other embodiments at a temperature of 200 °C or above, in other embodiments at a temperature of 205 °C or above, and in other embodiments at a temperature of 210 °C or above. In some embodiments, the flash-spinning is performed at a temperature from about 195 °C to about 205 °C, and in other embodiments, at a temperature from about 190 °C to about 200 °C.

[0257] In some embodiments, the spin agent comprises one or more hydrocarbons. In some embodiments, the one or more hydrocarbons of the spin agent are selected from n-pentane, cyclopentane, hexane, cyclohexane, 2-methylbutane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, or mixtures thereof. In some embodiments, the spin agent comprises n-pentane, cyclopentane or a mixture thereof. In some embodiments, the spin agent consists essentially of or consists of n-pentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of a mixture of n-pentane and cyclopentane, in other embodiments, the spin agent comprises, consists essentially of, or consists of from about 60 to about 90 weight percent n-pentane and from about 40 to about 10 weight percent cyclopentane, in other embodiments from about 60 to about 80 weight percent n-pentane and from about 40 to about 20 weight percent cyclopentane. In some embodiments, the spin agent comprises or consists essentially of a mixture of n-pentane, cyclopentane, and branched hydrocarbon with 5 or 6 carbon atoms. In some embodiments, the spin agent comprises, consists essentially of, or consists of a mixture of n-pentane, cyclopentane, and branched hydrocarbon with 5 or 6 carbon atoms. In some embodiments, the spin agent comprises or consists essentially of a mixture of (1) n-pentane, (2) cyclopentane, and (3) 2-methylbutane, 2-methylpentane, 3-methylpentane, or 2,2-dimethylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consist of a mixture of (1) n-pentane, (2) cyclopentane, and (3) 2-methylbutane, 2-methylpentane, 3-methylpentane, or 2,2-dimethylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consist of a mixture of (1) from about 60 to about 85 weight percent n-pentane, (2) from about 13 to about 33 weight percent cyclopentane, and (3) from about 2 to about 7 weight percent 2,2-dimethylbutane, 2-methylpentane, 3-methylpentane, or 2,2-dimethylbutane.

[0258] The spin fluid may include additives, such as antioxidants or acid scavengers in minor amounts. In some embodiments, the spin fluid comprises additives in an amount of about 1.5 weight percent or less, based on the total amount of the spin fluid, and in other embodiments in an amount of about 0.1 weight percent or less, based on the total amount of the spin fluid.In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 190 °C to about 205 °C using a spin fluid comprising about 12.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid, and comprising a spin agent which comprises, consists essentially of, or consists of n-pentane. In other embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 195 °C to about 205 °C using a spin fluid comprising about 14.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid, and comprising a spin agent which comprises, consists essentially of, or consists of n-pentane.

[0259] In some embodiments, the plexifilamentary fibrils are spun using a spin fluid comprising about 12.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid, and at a spin temperature of about 190 °C or more, about 195 °C or more, or about 200 °C or more, or about 205 °C or more, or about 210 °C or more. In some embodiments, the plexifilamentary fibrils are spun using a spin fluid comprising about 14.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid, and at a spin temperature of about 190 °C or more, about 195 °C or more, or about 200 °C or more, or about 205 °C or more, or about 210 °C or more. In some embodiments, the plexifilamentary fibrils are spun using a spin fluid comprising about 15.0 to about 17.0 weight percent polymer, based on the total amount of the spin fluid, and at a spin temperature of about 190 °C or more, about 195 °C or more, or about 200 °C or more, or about 205 °C or more, or about 210 °C or more. In some embodiments, the plexifilamentary fibrils are spun at a spin temperature from about 190 °C or more, about 195 °C to about 205 °C using a spin fluid comprising about 14.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid.

[0260] Thermal Whole Surface Bonding and Cooling

[0261] After the sheet is formed into a consolidated sheet as described herein, the consolidated sheet is then subjected to thermal whole surface bonding without applying substantial pressure to the sheet.

[0262] Thermal whole surface bonding may be carried out by means of a heated drum or roll with the consolidated sheet placed in contact with the surface of the heated drum or roll. The whole surface bonding is in principle known in the art, including, but not limited to, using a heated drum as described, for example in US 3,442,740, US 3,532,589 and US 5,068,796. Shrinkage of the sheet during the whole surface bonding is controlled by the application of a belt without applying substantial pressure to the nonwoven sheet. In some embodiments, without substantial pressure means a pressure of from about 0.02 barg to about 0.25 barg, in other embodiments from about 0.05 barg to about 0.15 barg, and in other embodiments from about 0.08 barg to about 0.12 barg.The drum or roll can have different surface treatments such as chrome plating, fluorinated coating or ceramic coating to assist in the release of the nonwoven sheet from the heated drum.

[0263] In some embodiments, the heated drum is internally heated by means of steam under pressure to a temperature from about 135 °C to 160 °C, in other embodiments to a temperature from about 135 °C to 155 °C, and in other embodiments to a temperature from about 138 °C to 149 °C. In some embodiments, the supplied pressure of the steam is from about 3.0 barg to about 5.0 barg, in other embodiments from about 3.0 barg to about 4.5 barg, in other embodiments from about 3.2 barg to about 4.0 barg, and in other embodiments from about 3.2 barg to about 3.6 barg. In some embodiments, the pressure of the steam is from about 3.0 barg to about 3.6 barg, and in other embodiments from about 3.0 barg to about 3.4 barg. In some embodiments, the pressure of the steam is from about 3.6 barg to about 4.2 barg, and in other embodiments from about 3.6 barg to about 4.0 barg. The internal temperature of the steam provides a temperature of from 135 °C to 160 °C. The surface temperature of the drum is lower compared to the internal temperature.

[0264] In some embodiments, the consolidated sheet is in contact with the heated rolls or drums for about 0.4 to about 2.53 seconds, in other embodiments for about 0.6 to about 2.5 seconds, 0.6 to about 2.3 seconds, in other embodiments for about 0.6 to about 2.0 seconds, and in other embodiments for about 1 to about 2 seconds. In some embodiments, the consolidated sheet is in contact with the heated rolls or drums for about 0.6 to about 1.5 seconds, and in other embodiments for about 0.8 to about 1.5 seconds. In some embodiments, the consolidated sheet is in contact with the heated rolls or drums for about 1.3 to about 2.3 seconds, in other embodiments for about 1.5 to about 2.3 seconds, and in other embodiments for about 1.5 to about 2 seconds.

[0265] It is to be understood that a similar degree of bonding (e.g., characterized by delamination strength) can be achieved with a shorter contact time and higher pressures of the steam and vice versa with a longer contact time and a lower pressure of the steam.

[0266] In some embodiments, when applying the whole surface bonding to the consolidated sheet without substantial pressure, a bonded sheet with a delamination strength of about 0.15 N to about 0.6 N is obtained. The delamination strength of the bonded sheet can be adjusted by controlling the applied pressure, the internal temperature of the drum, and the contact time. In some embodiments, the applied pressure lies in the range from about 0.02 barg to about 0.25 barg, and the internal temperature of the drum lies in the range of about 142 °C to about 151 °C. If the delamination strength is below 0.15 N, the bonded sheet will have insufficient mechanical strength and its surface will be excessively prone to damage during handing. If the delamination strength is above 0.6 N, the properties of the bonded sheet will not be improved sufficiently by subsequent softening steps.After the sheet is formed into a bonded sheet by whole surface bonding as described herein, the bonded sheet is cooled by passing it onto a cooling roll, which is cooled by passing a heat transfer liquid through the interior of the roll. In some embodiment, the heat transfer liquid is water. In some embodiment, the temperature of the passing water has a temperature between about 10 °C and about 50 °C. In some embodiment, the surface of the cooling roll is chrome coated to allow for the release of the nonwoven sheet and to allow for a good heat transfer from the nonwoven sheet to the cooling roll. In some embodiments, the bonded sheet is cooled to a temperature of about 80 °C or below, and in other embodiments, to a temperature of about 70 °C or below. In some embodiments, the bonded sheet is cooled to a temperature of about 20 °C or above, in other embodiments, to a temperature of about 30 °C or above, and in other embodiments, to a temperature of about 40 °C or above. In some embodiments, the bonded sheet is cooled to a temperature from about 20 °C to about 80 °C, in other embodiments, to a temperature from about 30 °C to about 80 °C, and in other embodiments, to a temperature from about 40 °C to about 70 °C.

[0267] Mechanical Softening by Blunt Pins

[0268] After the consolidated sheet is thermally surface bonded and cooled as described herein, the cooled bonded sheet is then subjected to a mechanical softening process to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils. During the mechanical softening process described herein, the cooled bonded sheet is passed through one or more nips between rolls which are driven at substantially the same surface speed as the speed of the cooled bonded sheet as it passes through the rolls, wherein each roll has interpenetrating pins and rotates in the opposite direction to the other roll, and wherein each interpenetrating pin is a blunt pin. This is in contrast to some prior art softening processes where the thermally bonded sheet is passed over a sequence of rolls that are driven at a different speed than the speed of the thermally bonded sheet. This difference in speed creates a rubbing effect that may create loose fibrils, which can jeopardize the barrier properties of the softened sheet.

[0269] By “blunt pin” is meant a pin that includes at least a distal end that has a blunt surface (i.e., a surface not having a sharp edge or point) and a shaft that has a surface.

[0270] As shown in Figure 4A, the blunt pin 10 has a proximal end 11 , a distal end 12, and a shaft 14. The shaft 14 may comprise one or more tapered portions. The shaft 14 of the blunt pin 10 may be any shape known in the art. The shaft 14 may be straight (i.e., having basically the same cross-section along the longitudinal axis of the shaft 14), ortapered toward the distal end 12 (i.e., having a decreasing cross-section along the longitudinal axis of the shaft 14 from the proximal end 11 toward the distal end 12), or a combination thereof (as exemplarily illustrated in Figure 4A). In some embodiments, the shaft 14 has edges 17 that are parallel, in other embodiments, the shaft 14 has edges 17 that are tapered toward the distal end 12,and in other embodiments, the shaft 14 has edges 17 that begin parallel at the proximal end 11 of the shaft 14 but then taper toward the distal end 12 of the shaft 14 such that the shaft 14 comprises a tapered end portion 13. The tapered end portion 13 may have more than one taper portion, each with an increasing angle of taper toward the distal end 12 of the shaft 14 (not shown). In some embodiments, the cross-section of the shaft 14 is a regular or irregular polygon, including, without being limited thereto, a rectangle, a pentagon, a hexagon, or an octagon. In some embodiments, the cross-section 14 of the shaft is a hexagon (as exemplarily illustrated in Figures 4A to 4C). In some embodiments, the cross-section of the shaft 14 is a square (as exemplarily illustrated in Figures 5A to 5C). In some embodiments, the crosssection of the shaft 14 is round, including a circle (see Figures 6Ato 6D and Figures 7Ato 7D) or an oval (not shown).

[0271] The distal end 12 has a blunt surface 15 that is flat. In some embodiments, the blunt surface 15 may have the shape of a regular or irregular polygon, including, without being limited thereto, a rectangle, a pentagon, a hexagon, or an octagon, when viewed from above. In some embodiments, the blunt surface has the shape of a hexagon (as exemplarily illustrated in Figures 4B and 4C). In some embodiments, the blunt surface 15 has the shape of a quadrilateral, for example a rectangle or a square (not shown). In some embodiments, the blunt surface 15 has the same or a different shape as the cross-section of the shaft 14. In some embodiments, both the blunt surface 15 and the cross-section of the shaft have the same shape, for example, the shape of a hexagon (as exemplarily illustrated in Figures 4Ato 4C). In some embodiments, both the blunt surface 15 and the cross-section of the shaft have the shape of a square (not shown). In some embodiments, the blunt surface 15 may have a different shape than the cross-section of the shaft 14 (as exemplarily illustrated in Figures 5A to 5C). In some embodiments, the blunt surface 15 has the shape of an octagon and the crosssection of the shaft 14 is a square (as exemplarily illustrated in Figures 5B and 5C). In some embodiments, the shaft 14 has the cross-section of an octagon and the blunt surface 15 has the shape of a square (not shown). In some embodiments, the blunt surface 15 has a circular shape (as exemplarily illustrated in Figures 6A to 6D and Figures 7A to 7D). In some embodiments, the blunt surface 15 has an oval shape (not shown). In some embodiments, the blunt surface 15 has a circular shape and the cross-section of the shaft 14 is circular as well (see Figures 6A to 6D and Figures 7A to 7D).

[0272] However, the distal end 12 may have any type of blunt surface (i.e., surface not having a sharp edge or point) known in the art, including, but not limited to, a blunt surface 15 that is rounded, forming a smooth curving surface. In some embodiments, the distal end 12 has a blunt surface 15 that is flat, and in other embodiments, the distal end 12 has a blunt surface 15 that is rounded. A blunt surface 15 that is rounded can be seen in Figures 6E and 7E.The distal end 12 and shaft 14 meet to form an edge 16. The edge 16 between the distal end 12 and shaft 14 may be any type of edge known in the art, including, but not limited to, a corner edge, a rounded edge, or a chamfer edge; provided, however, that all corner edges must form an angle 18 greater than 90 degrees. In some embodiments, the edge 16 between the distal end 12 and the shaft 14 is a corner edge at an angle greater than 90 degrees, in other embodiments, the edge 16 between the distal end 12 and the shaft 14 is a corner edge at an angle greater than 100 degrees, and in other embodiments, the edge 16 between the distal end 12 and the shaft 14 is a corner edge at an angle greater than 135 degrees. In some embodiments, the edge 16 is a rounded edge, and in other embodiments, the edge 16 is a chamfer edge.

[0273] In some embodiments, the edge 16 between the distal end 12 and shaft 14 is a rounded edge having a radius of curvature of from about 0.1 mm to about 0.5 mm, and in other embodiments, having a radius of curvature of from about 0.25 mm to about 0.4 mm.

[0274] In some embodiments, the shaft 14 has a cylindrical shape (see Figures 6A to 7E). In some embodiments, the cylindrical shaft 14 may comprise a tapered end portion 13 (see Figures 6Ato 6E), in other embodiments the cylindrical shaft 14 may be fully tapered from the proximal end 11 toward the distal end 12 (not shown), i.e., the shape of the blunt pin 10 has the shape of a truncated cone, and in some other embodiments the cylindrical shaft 14 does not comprise a tapered portion (see Figures 7Ato 7E).

[0275] In some embodiments, the shaft 14 has a cylindrical shape with a circular cross-section at the proximal end 11 , the cross section at the proximal end 11 having a diameter of from about 0.6 mm to about 2 mm, in other embodiments, having a diameter of from about 0.8 mm to about 1.8 mm, and in other embodiments, having a diameter of from about 1.0 mm to about 1.6 mm.

[0276] In some embodiments, the distal end 12 of the blunt pins 10 has a blunt surface having a diameter of from about 0.4 mm to about 1.8 mm, in other embodiments, having a diameter of from about 0.6 mm to about 1.6 mm, and in other embodiments, having a diameter of from about 1.0 mm to about 1.4 mm.

[0277] In some embodiments, the blunt pins 10 have a length from about 0.5 mm to about 6 mm, in other embodiments, from about 1 mm to about 4 mm, and in other embodiments, from about 2 to 3 mm.

[0278] In some embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 100 % of the diameter of the base of the shaft 14, in other embodiments the diameter of the distal end 12 of the blunt pins 10 is less than 90 % of the diameter of the base of the shaft 14, in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 80 % of the diameter of the base of the shaft 14, in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 70 % of the diameter of the base of the shaft 14,in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 60 % of the diameter of the base of the shaft 14, in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 50 % of the diameter of the base of the shaft 14, in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 40 % of the diameter of the base of the shaft 14, in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 30 % of the diameter of the base of the shaft 14, in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 20 % of the diameter of the base of the shaft 14, and in other embodiments, the diameter of the distal end 12 of the blunt pins 10 is less than 10 % of the diameter of the base of the shaft 14.

[0279] Figures 6A to 6E and Figures 7A to 7E show different cylindrical blunt pins 10 with blunt surfaces 15 with varying diameters. The blunt surface 15 can have a slightly smaller diameter than the smallest diameter of the tapered end portion 13 of the shaft 14 (see Figure 6C), can have a significantly smaller diameter than the smallest diameter of the tapered end portion 13 of the shaft 14 (see Figure 6D), can be a rounded distal end 12 (see Figure 6E), or can have the same diameter as the smallest diameter of the tapered end portion 13 of the shaft 14 (not shown). The blunt surface 15 can have a slightly smaller diameter than the diameter of the shaft 14 (see Figure 7C), can have a significantly smaller diameter than the diameter of the shaft 14 (see Figure 7D), or can be a rounded distal end 12 (see Figure 7E).

[0280] The blunt pin 10 may include one or more intermediate surfaces 20 between the distal end 12 and the proximal end 11. In some embodiments the one or more intermediate surfaces 20 are comprised in one or more tapered portions of the shaft 14, including, but not limited to the tapered end portion 13, as exemplarily shown in Figures 4A and 5A. Each of the one or more intermediate surfaces 20 meet with an adjacent surface within the tapered portion to form an edge 17. The edge 17 between each of the one or more intermediate surfaces 20 and the adjacent surfaces within the tapered portion 13 may be any type of edge known in the art, including, but not limited to, a corner edge, a rounded edge, or a chamfer edge.

[0281] The blunt pin 10 may include one or more intermediate surfaces 22 between the distal end 12 and the proximal end 11. In some embodiments the one or more intermediate surfaces 22 meet with one or more adjacent intermediate surfaces 20 to form an edge 19, the one or more intermediate surfaces 20 and 22 being adjacent along the longitudinal axis of the shaft 14. The edge 19 may be any type of edge known in the art, including, but not limited to, a corner edge, a rounded edge, or a chamfer edge provided, however, that all corner edges 19 must form an angle between adjacent intermediate surfaces 20 and 22 greater than 90 degrees. In some embodiments, the edge 19 between adjacent intermediate surfaces 20 and 22 is a corner edge at an angle greater than 90 degrees, in other embodiments, the edge 19 between adjacent intermediate surfaces 20 and 22 is a corner edge at an angle greaterthan 100 degrees, and in other embodiments, the edge 19 between adjacent intermediate surfaces 20 and 22 is a corner edge at an angle greater than 135 degrees.

[0282] The blunt pins 10 of each roll are arranged in an array and have distal ends 12 that are equidistant from the roll’s axis. The array of blunt pins 10 on one roll interpenetrates the array of blunt pins 10 on the opposite roll by a depth that is at least equal to the thickness of the sheet.

[0283] In some embodiments, the blunt pins 10 are separated by about 1.5 mm to about 5.0 mm center-to-center in the machine direction (MD) and by about 1.5 mm to about 5.0 mm center-to-center in the transverse direction (XD) direction. In some embodiments, the blunt pins 10 are separated by about 2.5 mm to about 4.0 mm center-to-center in the machine direction, and in other embodiments, the blunt pins 10 are separated by about 3.0 mm to about 3.5 mm center-to-center in the machine direction. In some embodiments, the blunt pins 10 are separated by about 2.5 mm to about 4.0 mm center-to-center in the transverse direction, and in other embodiments, the blunt pins 10 are separated by about 3.0 mm to about 3.5 mm center-to-center in the transverse direction. The blunt pins 10 in the machine direction may be separated by the same or a different distance as the distance separating the blunt pins 10 in the transverse direction.

[0284] The blunt pins 10 may be arranged in various arrays, including, but not limited to, square, rectangular, and triangular arrays. In some embodiments, the blunt pins 10 are arranged in an array wherein the ratio of center-to-center distance between adjacent blunt pins 10 to the diameter of the adjacent blunt pins 10 is from about 2:1 to about 10:1 , and in other embodiments, from about 3:1 to about 5:1.

[0285] The absence of sharp points and / or sharp edges on the distal end 12 of the blunt pins 10 allows the mechanical softening process to operate with an increased degree of interpenetration of the array of blunt pins 10 on one roll into the array of blunt pins 10 on the other roll without compromising the barrier properties of the sheet. In contrast thereto, the use of other pin configurations, such as the square edged pins of US 3,920,874 and US 3,811 ,979, may lead to excessive localized deformation or fracture at higher degrees of interpenetration, resulting in compromised barrier properties in the softened sheet. The use of a blunt pin 10 allows a softer product to be achieved in a single step, whereas multiple pin softening steps may be needed with other pin configurations to reach the desired level of softness for a garment application.

[0286] Mechanically softening the cooled bonded sheet using interpenetrating blunt pins 10 as described above can be applied, irrespective of whether the sheet of nonwoven flash-spun plexifilamentary fibrils is originally formed from the spinning process as described herein using a spin agent comprising one or more hydrocarbons or formed from the spinning process as described herein using a spin agent comprising a mixture of chlorine- and fluorine-containingsolvents. Contrary to the mechanically softening described in US 3,920,874, the mechanically softening using interpenetrating blunt pins 10 as described herein can also be used to soften a bonded sheet wherein the average elongation is below 10 %.

[0287] In some embodiments, the cooled bonded sheet is mechanically softened by passing it through one or more nips between rolls, each rotating in the opposite direction as the other roll and each bearing a multiplicity of interpenetrating square-ended pins. By “square-ended pin” is meant that the distal end of the pin and the shaft of the pin form an edge at an angle 18 of 90 degrees or less providing a relatively sharp edge around the periphery of each pin end. In some embodiments, the square-ended pins have a square edged cylindrical shape as disclosed in US 3,920,874 and US 3,811 ,979.

[0288] In some embodiments, when using a thermally bonded sheet originally formed from the spinning process as described herein using a spin agent comprising a mixture of chlorine-and fluorine-containing solvents, the cooled bonded sheet is mechanically softened (as described in US 5,966,785 or US 6,195,854) by passing it through a nip of two rolls, each rotating in the opposite direction as the other roll, wherein one of the rolls bears a multiplicity of knobs and the other roll is a soft rubber back-up roll.

[0289] In some embodiments, the cooled bonded sheet is passed once through the mechanical softening step as described herein, and in other embodiments, the cooled bonded sheet is passed multiple times through the mechanical softening step as described herein. The depth of interpenetration of the pins may be adjusted as desired for each pass through the mechanical softening step as described herein. In some embodiments, the depth of interpenetration of the pins is the same for each pass through the mechanical softening step as described herein, and in other embodiments, the depth of interpenetration of the pins is different in at least one pass through the mechanical softening step as described herein than the depth of interpenetration of the pins used in any other passes. In some embodiments, the configuration of the pins is different in at least one pass through the mechanical softening step as described herein than the configuration of the pins used in any other passes.

[0290] Additional Embossing followed by Softening

[0291] In some embodiments, after the sheet is formed into a cooled sheet as described herein, the cooled sheet is subjected to an embossing step by any methods known in the art, including, but not limited to, using heated embossing roll(s) and rubber coated back-up roll(s) to bond one or two sides of the cooled sheet, to form an embossed sheet. In the embossing step, thermal bonding occurs under application of heat and substantial pressure.

[0292] In some embodiments, only one side of the cooled sheet is embossed. In other embodiments, one side of the cooled sheet is embossed and the other side of the cooled sheetis calendered by passing the sheet through a nip formed between a flat smooth roll and a rubber coated back-up roll.

[0293] The embossing roll(s) apply heat and pressure locally over a portion of the surface of the cooled sheet to bond the cooled sheet and form an embossed pattern. The degree of bonding can vary by adjusting the temperature and pressure, and the length of time during which these are applied. In some embodiments, each embossing roll(s) have a temperature from about 135 °C to about 210 °C during bonding, and in other embodiments each embossing roll(s) have a temperature from about 140 °C to about 155 °C during bonding. The nip pressure can be varied with embossing roll configuration and engraving patterns, backup roll diameter, rubber hardness and thickness.

[0294] In some embodiments, the cooled sheet wraps the heated embosser roll before the nip point such that the angle between the direction of entry and the direction of exit (the wrap angle) is from about 10 °C to about 140 °C, in other embodiments, the wrap angle is from about 10 °C to about 100 °C, and in other embodiments, the wrap angle is from about 10 °C to about 60 °C.

[0295] In some embodiments, the static pressure in the nip of the embosser is between about 150 kPa and about 750 kPa. An “embosser” as used herein means a pair of two rolls forming a nip, one being a heated embossing roll and the other being a rubber coated back-up roll. In some embodiments, when using a cooled sheet originally formed from the spinning process as described herein using a spin agent comprising one or more hydrocarbons as spin agent, the static pressure in the nip of the embosser is between about 150 kPa to about 750 kPa, and in other embodiments from about 250 kPa to about 600 kPa. In some embodiments, when using a cooled sheet originally formed from the spinning process as described herein using a spin agent comprising a mixture of chlorine- and fluorine-containing solvents as spin agent, the static pressure in the nip of the embosser is between about 150 kPa to about 600 kPa, and in other embodiments from about 150 kPa to about 500 kPa.

[0296] In some embodiments, the cooled sheet may be in contact with pre-heating rolls before thermally bonding and / or may be in contact with cooling rolls after thermally bonding, as described in US 5,972,147.

[0297] The embossing roll(s) may be made from any suitable material known in the art. In some embodiments, the embossing roll(s) are metal.

[0298] The embossing roll(s) are engraved with a pattern. The embossing roll(s) may include any pattern known in the art, including, but not limited to, a point pattern as described in US 3,478, 141 , US 6,610,390, and US 2004 / 241399 A1, a rib pattern as described in US 2003 / 0032355 A1 and US 2003 / 0165667 A1 , a linen pattern as described in US 2008 / 0220681 A1 , a random pattern as described in US 7,744,989, and other variations of patterns as described in US 5,620,779 and US 5,964,742. The degree of bonding can varydepending on the embossing pattern chosen. Exemplary illustrations of suitable embossing patterns are shown in Figures 1 to 3: exemplary point patterns are illustrated in FIGS. 1A to 1C, an exemplary rib pattern is illustrated in FIG. 2, and an exemplary linen pattern is illustrated in FIG. 3.

[0299] Each side of the cooled sheet may be embossed using the same pattern or a different pattern. In some embodiments, the cooled sheet is embossed on both sides using the same pattern, and in other embodiments, the cooled sheet is embossed on both sides using different patterns. In some embodiments, the cooled sheet is embossed on both sides using a point pattern, in other embodiments, the cooled sheet is embossed on both sides using a rib pattern, and in other embodiments, the cooled sheet is embossed on both sides using a linen pattern. In some embodiments, the cooled sheet is embossed on one side using a point pattern and, on another side, using a rib pattern, in other embodiments, the cooled sheet is embossed on one side using a point pattern and, on another side, using a linen pattern, and in other embodiments, the cooled sheet is embossed on one side using a rib pattern and, on another side, using a linen pattern.

[0300] The patterns on the embossing roll(s) may be any suitable depth known in the art. Each embossing roll may have patterns at the same depth or at different depths. In some embodiments, the cooled sheet is embossed using embossing rolls having patterns at different depths such that certain portions of the cooled sheet are subjected to more bonding than others.

[0301] The percentage of surface area on each side of the cooled sheet that is embossed may vary. In some embodiments, from about 6 % to about 85 % of the area of at least one side of the cooled sheet is embossed, in other embodiments, from about 10 % to about 60 %, in other embodiments, from about 15 % to about 60 %, in other embodiments, from about 20 % to about 60 %, in other embodiments, from about 26 % to about 60 %, in other embodiments, from about 30 % to about 60 %, and in other embodiments, from about 50 % to about 85 %. In some embodiments, about 6 % to about 85 % of the area of both sides of the cooled sheet is embossed, in other embodiments, from about 10 % to about 60 %, in other embodiments, from about 15 % to about 60 %, in other embodiments, from about 20 % to about 60 %, in other embodiments, from about 26 % to about 60 %, in other embodiments, from about 30 % to about 60 %, and in other embodiments, from about 50 % to about 85 %. In some embodiments, about 50 % to about 85 % of the area of one side of the cooled sheet is embossed using a linen pattern, and about 15 % to about 60 % or about 20 % to about 60 % or about 26 % to about 60 % of the area of other side of the cooled sheet is embossed using a rib pattern.

[0302] In other embodiments, one side of the cooled sheet is embossed and the other side of the cooled sheet is whole surface bonded.After the cooled sheet is embossed as described herein, the embossed sheet is then subjected to a mechanical softening process to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils. During the mechanical softening process described herein, the embossed sheet is passed through one or more nips between rolls which are driven at substantially the same surface speed as the speed of the embossed sheet as it passes through the rolls. This is in contrast to some prior art softening processes where the thermally bonded sheet is passed over a sequence of rolls that are driven at a different speed than the speed of the thermally bonded sheet. This difference in speed creates a rubbing effect that may create loose fibrils, which can jeopardize the barrier properties of the softened sheet.

[0303] In some embodiments, the embossed sheet is mechanically softened by passing it through one or more nips between rolls, each rotating in the opposite direction as the other roll and each bearing a multiplicity of interpenetrating square-ended pins. By “square-ended pin” is meant that the distal end of the pin and the shaft of the pin form an edge at an angle 18 of 90 degrees or less providing a relatively sharp edge around the periphery of each pin end. In some embodiments, the square-ended pins have a square edged cylindrical shape as disclosed in US 3,920,874 and US 3,811 ,979. In some embodiments, the embossed sheet is mechanically softened by passing it through one or more nips between rolls, each rotating in the opposite direction as the other roll and each bearing a multiplicity of blunt pins, as described herein.

[0304] In some embodiments, the embossed sheet is mechanically softened (as described in US 5,966,785 or US 6,195,854) by passing it through a nip of two rolls, each rotating in the opposite direction as the other roll, wherein one of the rolls bears a multiplicity of knobs and the other roll is a soft rubber back-up roll.

[0305] In some embodiments, the embossed sheet is passed once through the mechanical softening step as described herein, and in other embodiments, the sheet of nonwoven flash-spun plexifilamentary fibrils is passed multiple times through the mechanical softening step as described herein.

[0306] The depth of interpenetration of the pins may be adjusted as desired for each pass through the mechanical softening step as described herein. In some embodiments, the depth of interpenetration of the pins is the same for each pass through the mechanical softening step as described herein, and in other embodiments, the depth of interpenetration of the pins is different in at least one pass through the mechanical softening step as described herein than the depth of interpenetration of the pins used in any other passes. In some embodiments, the configuration of the pins is different in at least one pass through the mechanical softening step as described herein than the configuration of the pins used in any other passes.Uses, Multilayer Structures, and Articles

[0307] In some embodiments, there is provided a sheet of nonwoven flash-spun plexifilamentary fibrils obtained or obtainable by the process described herein.

[0308] In some embodiments, the obtained sheet has

[0309] (a) a basis weight from about 35 g / m2to about 58 g / m2,

[0310] (b) a Gurley Hill porosity of about 20 seconds or less,

[0311] (c) a particle filtration efficiency of about 90 % or more,

[0312] (d) a handle-o-meter stiffness from 0.5 N to about 1.20 N,

[0313] (e) a delamination strength from about 0.1 N to about 1.0 N, and

[0314] (f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0315] The sheet of nonwoven flash-spun plexifilamentary fibrils as described herein has many uses and may be used in a variety of packaging applications, including, but not limited to, active packaging, covers for equipment including car covers, cargo covers, mattress covers, industrial bags, consumer bags, medical packages, and further applications.

[0316] In some embodiments, the sheet of nonwoven flash-spun plexifilamentary fibrils as described herein may be used as a garment, including, but not limited to, as a protective garment or a chemical protective garment. In some embodiments, the garments as described herein may be used in various environments to protect the wearer from potential particulate hazards as well as acidic or basic aqueous liquid hazards which can be found in applications like chemical processing, pharmaceutical handling, paint applications, general maintenance, etc. In some embodiments, the garments as described herein help to protect the wearer against the hazard of a chemical permeating through the garment during the time of use (resistance to chemical permeation). A basic solution such as sodium hydroxide (NaOH), when used as a cleaning agent, is an example of an aqueous liquid hazard. In addition, a wearer may experience closed space environments as well as different temperature and humidity conditions. In some embodiments, the garments as described herein help to provide a balanced level of durability (i.e., high seam strength, trapezoidal tear, puncture, abrasion resistance) combined with comfort (i.e., low water vapor resistance and high softness I low handle-o-meter stiffness). For example, high seam strength helps to protect the wearer of the garments against unwanted tearing of the seams which could compromise the integrity of the garment. Furthermore, low water vapor resistance (Ret) and high garment softness help to provide appropriate comfort to the wearer in different climate conditions.

[0317] In some embodiments, the protective garment comprises a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene. In some embodiments, the protective garment is a single-layer protective garment comprising one or more bonded sheets of flash-spunplexifilamentary fibrils of polyethylene. In instances where the single-layer protective garment comprises two or more bonded sheets of flash-spun plexifilamentary fibrils of polyethylene, the two or more bonded sheets are combined or attached adjacent to each other to form one single layer. In some embodiments, the protective garment is a single-layer protective garment comprising one or more bonded sheets of flash-spun plexifilamentary fibrils of polyethylene, but not comprising sheets which are not bonded sheets of flash-spun plexifilamentary fibrils of polyethylene.

[0318] In some embodiments, the protective garment is a full body coverall, a coat, a hat, pants, or gloves.

[0319] In some embodiments, the protective garment comprises, consists essentially of, or consists of pieces of one or more bonded sheets of flash-spun plexifilamentary fibers, at least one stitched seam comprising a yarn, optionally at least one zipper, and optionally one or more elastic bands. At the seam, at least two pieces of bonded sheets are stitched together, and form a single-layer protective garment. In some embodiments, the yarn of the stitched seam may include a hydrophobic yarn to improve the impermeability of stitched seams, as described in US 2013 / 0232675 A1. In some embodiments, the stitched seam may be covered with a protective tape at the outside of the garment yarn to improve the impermeability of the stitched seams.

[0320] In some embodiments, the protective garment comprises, consists essentially of, or consists of pieces of one or more bonded sheets of flash-spun plexifilamentary fibrils, at least one welded seam, optionally at least one zipper, and optionally one or more elastic bands. Welded seams may be ultrasonically welded or combined by other means using heat and pressure.

[0321] In some embodiments, the protective garment comprises one or more elastic bands. In some embodiments, an elastic band may be present in the back of the protective garment to provide comfort and fit. In some embodiments, elastic bands may be present at the end of the arms or legs of the protective garment to provide a closer fit to the body of the wearer. In other embodiments, the protective garment may have a hood, which may include an elastic band, as described for example in US 9,155,922. The hood opening for a wearer’s face may have an elastic band, for example, to achieve an improved fit.

[0322] In some embodiments, the protective garment comprises a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene as defined herein, wherein the garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / Wto about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

[0323] In some embodiments, the protective garment comprises a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene, wherein the garment has a basis weight from about35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / Wto about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

[0324] In some embodiments, the protective garment has a basis weight from about 37 g / m2to about 58 g / m2, from about 38 g / m2to about 49 g / m2, from about 40 g / m2to about 49 g / m2, from about 40 g / m2to about 44 g / m2, or from about 44 g / m2to about 49 g / m2, in other embodiments, the protective garment has a Ret from about 3 m2Pa / W to about 8 m2Pa / W, from about 3 m2Pa / W to about 6 m2Pa / W, from about 4 m2Pa / W to about 6 m2Pa / W, or from about 3 m2Pa / W to about 5 m2Pa / W.

[0325] In some embodiments, the protective garment has an average trapezoidal tear strength from about 10 N to about 40 N, from about 10 N to about 30 N, from about 15 N to about 30 N, or from about 20 N to about 30 N, in other embodiments, the protective garment has an average puncture resistance from about 10 N to about 30 N, from about 10 N to about 25 N, or from about 12 N to about 25 N.

[0326] In some embodiments, the protective garment has an average abrasion resistance of 10 rubs or above, of 40 rubs or above, of 100 rubs or above, of 400 rubs or above, of 1000 rubs or above, or of 2000 rubs or above.

[0327] In some embodiments, the protective garment has a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 10 wt% NaOH or 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, in other embodiments, the protective garment has a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0328] In some embodiments, the protective garment has a resistance to chemical permeation, BTi o, measured according to ISO 6529 against 10 wt% NaOH or 40 wt% NaOH and against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0329] In some embodiments, the protective garment has a handle-o-meter stiffness from about 0.05 N to about 1.2 N, from about 0.1 N to about 1.2 N, from about 0.2 N to about 1.2 N, from about 0.3 N to about 1.0 N, from about 0.4 N to about 1.0 N, from about 0.3 N to about O.8 N, from about 0.3 N to about 0.6 N, or from about 0.4 N to about 0.6 N. In some embodiments, the protective garment has a handle-o-meter stiffness from about 0.05 to about 0.6 N, from about 0.05 N to about 0.5 N, from about 0.1 to about 0.5 N, from about 0.1 to about 0.4 N, or from about 0.1 to about 0.3 N.

[0330] In other embodiments, the protective garment has an average seam strength from about 50 N to about 300 N, from about 50 N to about 200 N, from about 75 N to about 200 N, from about 75 N to about 150 N, or from about 75 N to about 125 N.In some embodiments, the protective garment has an opacity of about 90 % or more, of about 93 % or more, of about 95 % or more, or of about 97 % or more. In some embodiments, the protective garment has an opacity from about 90 % to about 99 %, from 90 % about to about 97 %, from about 93 % to about 97 %, from about 95 % to about 99 %, or from about 95 % to about 97 %.

[0331] In some embodiments, the protective garment has an average Type 5 inward leakage of 10 % or less, of 5 % or less, of 3 % or less, of 2 % or less, or of 1 % or less.

[0332] In some embodiments, the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / Wto about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BTi,0>measured according to ISO 6529 against 10 wt% NaOH or against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, or a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0333] In some embodiments, the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a handle-o-meter stiffness from about 0.05 N to about 0.6 N, from about 0.1 N to about 0.5 N, or from about 0.2 N to about 0.4 N, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BT-i o, measured according to ISO 6529 against 10 wt% NaOH or against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, or a resistance to chemical permeation, BTi0, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0334] In some embodiments, the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / Wto about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, in other embodiments, the protective garment has a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 200 N, an average trapezoidal tear strength of from about 10 N to about 30 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% or 40 % NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, or a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% or 30 wt% H2SO4of 60min or above, of 120 min or above, of 240 min or above, or of 480 min or above, and in other embodiments, it has a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0335] In some embodiments, the protective garment has a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, and a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 10 wt% or 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, or a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, and in other embodiments, it has a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4 of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0336] In some embodiments, the protective garment has a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 12 N to about 20 N, and an average Type 5 inward leakage of 5 % or less, in other embodiments, it further has a resistance to chemical permeation, BT1 0, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4 of 120 min or above, or a resistance to chemical permeation, BT10, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 120 min or above.

[0337] In some embodiments, the protective garment has a basis weight from about 38 g / m2to about 49 g / m2, a handle-o-meter stiffness from about 0.05 N to about 0.6 N, or from about 0.1 N to about 0.5 N, from about 0.2 N to about 0.4 N, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 12 N to about 20 N, and an average Type 5 inward leakage of 5 % or less, in other embodiments, it further has a resistance to chemical permeation, BT-1,0, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 120 min or above, or a resistance to chemical permeation, BT10, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 120 min or above.

[0338] In some embodiments, the protective garment has a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 50 N to about 150 N, an average trapezoidal tear strength from about 15 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, an average abrasionresistance of 400 rubs or above or of 1000 rubs or above, an average tensile strength from about 70 N to about 180 N, or from about 90 N to about 160 N, and a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4 of 120 min or above.

[0339] In some embodiments, the outside of the garment is embossed with a linen pattern, a rib pattern, or a point pattern, or the inside of the garment is embossed with a linen pattern, a rib pattern, or a point pattern, wherein the embossing pattern on the outside and the inside of the garment can be the same or different.

[0340] In some embodiments, the polyethylene is a high-density polyethylene (HDPE), a blend or mixture of a high-density polyethylene (HDPE) with low-density polyethylene (LDPE), or a blend or mixture of a high-density polyethylene (HDPE) with linear low-density polyethylene (LLDPE), in particular a blend or mixture of a high-density polyethylene (HDPE) with a melt flow rate (ISO 1133 190 °C / 2160 grams) from 0.05 g / 10min to 30 g / 10min and high-density polyethylene (HDPE) with a melt flow rate (ISO 1133, 190 °C / 21 ,600 grams) from 1 g / 10min to 15 g / 10min, or a blend or mixture of a high-density polyethylene (HDPE) with a melt flow rate (ISO 1133 190 °C / 2160 grams) from 0.05 g / 10min to 4 g / 10min and high-density polyethylene (HDPE) with a melt flow rate (ISO 1133, 190 °C / 21,600 grams) from 1 g / 10min to 15 g / 10min.

[0341] Further embodiments relate to a multilayer structure comprising at least one sheet of nonwoven flash-spun plexifilamentary fibrils as described herein, and at least one further sheet or a film.

[0342] In some embodiments, the multilayer structure comprises a film that is a microporous film. In one embodiment, the microporous film is a film that is filled and stretched as described in US 9,809,004 B2. Microporous films from highly filled polymers, usually polyolefins, may be prepared by any methods known in the art. Typically, a combination of a polyolefin, usually a polyethylene, is compounded with a filler, usually calcium carbonate, and extruded and stretched into a film to form a microporous film. Suitable examples of microporous films include those described in US 4,472,328, US 4,350,655, and US 4,777,073. A multilayer structure comprising a microporous film and at least one sheet of nonwoven flash-spun plexifilamentary fibrils as described herein can be used in a variety of applications, including but not limited to protective apparel.

[0343] In some embodiments, the multilayer structure is a laminated structure comprising a microporous film laminated with at least one sheet of nonwoven flash-spun plexifilamentary fibrils as described herein. In some embodiments, a microporous film and a sheet of nonwoven flash-spun plexifilamentary fibrils may be laminated using an adhesive layer situated in contact with a least a portion of both the microporous film and the sheet of nonwoven flash-spun plexifilamentary fibrils, as described in US 9,809,004 B2.Further embodiments relate to use of the sheet of nonwoven flash-spun plexifilamentary fibrils as described herein for preparing a multilayer structure.

[0344] Further embodiments relate to an article comprising at least one sheet of nonwoven flash-spun plexifilamentary fibrils as described herein or comprising at least one multilayer structure as described herein. In some embodiments, the article is selected from active packages, including bags or sachets, covers for equipment including car covers, cargo covers, mattress covers, industrial bags, consumer bags, medical packages, and further applications. In some embodiments, the article is medical packaging, including, but not limited to, medical wrap for the packaging of medical items such as surgical instruments during sterilization.

[0345] EXAMPLES

[0346] Different bonded and softened sheets of nonwoven flash-spun plexifilamentary fibrils have been prepared. The experimental procedure and results are provided below. These examples are given to illustrate exemplary embodiments of the invention and should not be interpreted as limiting in anyway.

[0347] Materials Used

[0348] N-pentane, CAS Nr 109-66-0, has an atmospheric boiling point of 36.1 °C and a molecular weight of 72.151 g / mol. The n-pentane used had a purity level above 95 percent by weight.

[0349] Cyclopentane, CAS Nr 287-92-3, has an atmospheric boiling point of 49.2 °C and a molecular weight of 70.13 g / mol. The cyclopentane used had purity level above 95 percent by weight.

[0350] Dichloromethane, CAS Nr. 75-09-2, has an atmospheric boiling of 39.6 °C and a molecular weight of 84.93 g / mol. The dichloromethane used had a purity level above 99.5 percent by weight.

[0351] 2H,3H-decafluoropentane (HFC-43-10mee), CAS Nr. 138495-42-8, has an atmospheric boiling point of 55 °C and a molecular weight of 252.05 g / mol. The 2H,3H-decafluoropentane used had a purity level above 99.5 percent by weight.

[0352] Polyethylene A has a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 1 Omin (ISO 1133 190 °C / 2.16 kg) and 22 g / 1 Omin (ISO 1133, 190 °C / 21.6 kg) , and a melting point of 135 °C.

[0353] Polyethylene B has a density >0.95 g / cm3(ISO 1183), a melt flow rate of 0.7 g / 1 Omin (ISO 1133, 190 °C / 2.16 kg) and a melting point of 135°C.Linear low-density polyethylene C (LLDPE, an ethylene-hexene copolymer) has a density of 0.934 g / cm3, a melt flow rate of 0.9 g / 10min (ISO 1133, 190 °C / 2.16kg), and a melting point of 124 °C.

[0354] Linear low-density polyethylene D (LLDPE, an ethylene-hexane copolymer) has a density of 0.918 g / cm3(ISO 1183) and a melt flow rate of 1.0 g / 10min (ISO 1133, 190 °C / 2.16kg).

[0355] The flash-spun sheets in the examples are produced using the flash spinning process described by US 3,227,794 and US 3,851 ,023. US 3,227,794 describes a flash spinning process where the pressure is reduced below the cloud point of the spin fluid before it is released into a zone of substantially lower temperature and pressure such that the spin agent flash evaporates and the polymer solidifies in the form of plexifilamentary fibrils. The cloud point pressure for hydrocarbon spin agents is reported in, but not limited to, US 5,147,586, US 6,004,672, and US 6,638,470, and for mixtures of DCM with fluorinated compounds in, but not limited to, US 6,004,672, US 7,300,968, US 7,179,413, US 5,672,307, US 5,874,036, and US 5,977,237.

[0356] Results

[0357] Examples E1 to E5

[0358] Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at a spin temperature of 200 °C, using spin fluids of 15.1 wt% or 16 wt% polymer in a hydrocarbon-based spin agent that was a mixture of n-pentane and cyclopentane (herein also referred to as “H”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 10min (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.

[0359] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently whole surface thermally bonded without substantial pressure, as reflected in Table 1. The thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0360] The cooled sheets of the examples were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of curvature of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheets.The spinning, bonding, cooling and softening conditions and the sheet properties are reported in Table 1, below.

[0361] Table 1: Summary of the sheet preparation of Examples E1 to E5.

[0362]

[0363] * not applicable ** not measured

[0364] Table 1 shows the ability of softening a whole surface thermally bonded sheet, resulting in that the desired combination of properties, with low Gurley Hill porosity and Frazier permeability, high particle filtration efficiency of above 99%, moderate stiffness, a desired delamination strength and MVTR, can be obtained when following the process of the invention.The softening process of the whole surface area bonded fabric results in a fabric with reduced stiffness, but without making a notable change in the Gurley air permeability, particle filtration efficiency or hydrostatic head.

[0365] Examples E6 and E7

[0366] Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at spin temperatures of 200 °C and 205 °C, using spin fluids of 16 wt% polymer in a hydrocarbon-based spin agent that was a mixture of n-pentane and cyclopentane (herein also referred to as “H”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 10min (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.

[0367] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently thermally bonded without substantial pressure, as reflected in Table 2. The thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0368] The cooled sheets of the examples were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of curvature of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheets.

[0369] The spinning, bonding, cooling and softening conditions and the sheet properties are reported in Table 2, below.

[0370] Table 2: Summary of the sheet preparation of Examples E6 and E7.

[0371]

[0372]

[0373] * not applicable ** not measured

[0374] Table 2 shows the application of a softening process to a nonwoven flash-spun fabric that is whole surface bonded (E7) or whole surface bonded and embossed (E6) with an elongation in at least one direction below 10%.

[0375] The softening process results in a reduction of the handle-o-meter value, without a notable change in the Gurley air porosity, particle filtration efficiency and the hydrostatic head. The fabric has a desired set of properties with high level of breathability and particle filtration efficiency.

[0376] Application of an embossing process results into a notable increase in the crock of the fabric, with only a moderate increase in the tensile strength.

[0377] Examples E8 to E10

[0378] Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at a spin temperature of 210 °C using spin fluids of 9.5 wt%, 10 wt% or 11 wt% polymer in a spin agent that was a mixture of dichloromethane and 2H,3H-decafluoropentane (herein also referred to as “D”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 1 Omin (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently whole surface thermally bonded without substantial pressure, as reflected in Table 3. The thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0379] The cooled sheets were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheets.

[0380] The spinning, bonding, cooling and softening conditions and sheet properties are reported in Table 3, below.

[0381] Table 3: Summary of the sheet preparation of Examples E8 to E10.

[0382]

[0383]

[0384] * not applicable ** not measured

[0385] T able 3 shows an example of a softening process for a whole surface thermally bonded fabric, where the elongation in at least one direction is below 12%. The softening process results in a softer fabric- without a notable change in the Gurley air porosity and the particle filtration efficiency.

[0386] Comparative Example CE1 and Example E11

[0387] Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at a spin temperature of 210 °C using spin fluids of 11 wt% polymer in a spin agent that was a mixture of dichloromethane and 2H,3H-decafluoropentane (herein also referred to as “D”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 10min (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.

[0388] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently thermally bonded without substantial pressure, as reflected in Table 4. The whole surface thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0389] The cooled bonded sheets were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of curvature of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheet.

[0390] The flash spin sheet according to comparative example CE1 did not receive a softening treatment.

[0391] The spinning, bonding, cooling and softening conditions and sheet properties are reported in Table 4, below.

[0392] Table 4: Summary of the sheet preparation of Example E11 and Comparative Example C1.

[0393]

[0394] * not applicable ** not measured

[0395] Table 4 shows the effect of a subsequent softening step after the whole surface thermal bonding step for example E11 , resulting in the desired combination of properties, with low Gurley Hill porosity, high particle filtration, and moderate stiffness. The fabric of comparative example CE1 had an undesirable high stiffness. The softening process of the whole surface thermally bonded fabric results in a reduction of the handle-o-meter, without a notable change in the Gurley air porosity and particle filtration efficiency.

[0396] Examples E12 to E13

[0397] Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at a spin temperature of 200 °C using spin fluids of 16 wt%polymer in a hydrocarbon-based spin agent that was a mixture of n-pentane and cyclopentane (herein also referred to as “H”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 10min (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.

[0398] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently thermally bonded without substantial pressure, as reflected in Table 5. The thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0399] The cooled bonded sheets were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of curvature of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheet.

[0400] The spinning, bonding, cooling and softening conditions and sheet properties are reported in Table 5, below.

[0401] Table 5: Summary of the sheet preparation of Examples E12 and E13.

[0402]

[0403]

[0404] ** not measured

[0405] Table 5 shows that the desired combination of properties, with low Gurley Hill porosity, high particle filtration, moderate stiffness, a desired delamination strength and MWTR, can be obtained when following the process of the invention. Examples E12 and E13 show the ability to soften a fabric that is whole surface thermally bonded and embossed, as demonstrated by a reduction in the handle-o-meter, without a notable change in the particle filtration efficiency, hydrostatic head or Gurley air porosity. Additionally, it is noted that the whole surface thermally bonded and embossed sheet has suitable crock values.

[0406] Comparative Examples CE2 to CE5 and Examples E14 to E17

[0407] Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at a spin temperature of 200 °C using spin fluids of 16 wt% polymer in a hydrocarbon-based spin agent that was a mixture of n-pentane and cyclopentane (herein also referred to as “H”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 10min (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.

[0408] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently whole surface thermally bonded without substantial pressure, as reflected in Table 6. The whole surface thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0409] The cooled bonded sheets were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of curvature of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheet.The flash spin sheets according to comparative examples CE2 and CE3 did not receive a softening treatment, while the comparative examples CE4 and CE5 did not receive a step of whole surface thermally bonding without substantial pressure and cooling.

[0410] The spinning, bonding, cooling and softening conditions and sheet properties are reported in Table 6, below.

[0411] Table 6: Summary of the sheet preparation of Examples E14 to E17 and Comparative Examples CE2 to CE5.

[0412]

[0413]

[0414] * not applicable, ** not measured

[0415] The examples in Table 6 show the effect of embossing the fabric with a rib pattern on both sides, between a prior whole surface bonding step and a subsequent softening step. Examples E14 and E15 are to be compared to comparative example CE2, and examples E16 and E17 to comparative example CE3. It is noted that the contact time for the whole surface bonding is in the range of 0.5 - 2 seconds, and the contact time for the embossing is in the range of about 8 to about 12 ms, meaning at least a factor 30 shorter.

[0416] The application of the additional embossing step results in a moderate change in physical properties such as tensile strength and elongation, but results in a notable increase in the surface robustness of the fabric, as can be seen from significantly higher crock values.

[0417] Additionally, the additional embossing step results in a reduction in the handle-o-meter values, meaning that the fabric becomes less stiff.

[0418] Moreover, this reduction in stiffness is not accompanied by any notable change in the hydrostatic head or particle filtration efficiency, whereas typically, a reduction in stiffness results in a reduction in barrier properties such as particle filtration efficiency and hydrostatic head.

[0419] Additionally, comparison with a fabric made with embossing a slightly consolidated sheet with embossing using a “rib” pattern on both sides, and subsequently softening it, comparative examples CE4 and CE5, shows that the fabric of this invention has a high value of the handle-o-meter, higher average strength, while maintaining a good breathability and particle filtration efficiency.

[0420] Comparative examples CE4 and CE5, which did not receive a step of thermally bonding without substantial pressure and cooling, had a considerably lower tensile strength and lower crock values than examples E14 to E19.Comparative Examples CE6 and CE7 and Examples E18 and E19 Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851,023 at a spin temperature of 195 °C using spin fluids of 15.1 wt% polymer in a hydrocarbon-based spin agent that was a mixture of n-pentane and cyclopentane (herein also referred to as “H”). The polymer used in examples E18 and E19 was a blend of polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133, 190 °C / 2.16 kg) and 22 g / 10min (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C, and linear low-density polyethylene C (LLDPE, an ethylene-hexene copolymer) with a density of 0.934 g / cm3(ISO 1183), a melt flow rate of 0.9 g / 1 Omin (ISO 1133, 190 °C / 2.16kg), and a melting point of 124 °C, in a 60:40 ratio by weight. In comparatives examples CE6 and CE7, the polymer used was a blend of polyethylene B with a density >0.95 g / cm3(ISO 1183) and a melt flow rate of 0.7 g / 10min (ISO 1133, 190 °C / 2.16 kg), and linear low- density polyethylene D (LLDPE, an ethylene-hexane copolymer) with a density of 0.918 g / cm3(ISO 1183) and a melt flow rate of 1.0 g / 1 Omin (ISO 1133, 190 °C / 2.16kg), in a 90: 10 ratio by weight.

[0421] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently whole surface thermally bonded without substantial pressure, as reflected in Table 7. The whole surface thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0422] The cooled bonded sheets were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of curvature of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheet.

[0423] The flash spin sheet according to comparative example CE6 did not receive a step of whole surface thermally bonding without substantial pressure and cooling, nor did it receive a softening step. The flash spin sheet according to comparative example CE7 did not receive a step of thermally bonding without substantial pressure and cooling.

[0424] The spinning, bonding, cooling and softening conditions and sheet properties are reported in Table 7, below.

[0425] Table 7: Summary of the sheet preparation of Comparative Examples CE6 and CE7 and Examples E18 and E19

[0426]

[0427]

[0428] * not applicable, ** not measured

[0429] The examples in Table 7 show that the step of thermally bonding without substantial pressure and subsequent cooling, with or without an additional step of embossing the fabric that is whole surface bonded, results in a moderate change of the physical properties such as tensile strength and elongation, but results in a notable increase in the surface robustness of the fabric, as can be seen from a notable increase of the crock value. Additionally, a comparison of examples E18 and E19 shows that the application of an additional embossing step results in reduction of the handle-o-meter value.

[0430] Comparative Examples CE8 to CE10 and Examples E20 to E24Flash-spun sheets were produced using the flash spinning process described by US 3,227,794 and US 3,851 ,023 at a spin temperature of 210 °C using spin fluids of 9.5 wt% or 10 wt% polymer in a spin agent that was a mixture of dichloromethane and 2H,3H-decafluoropentane (herein also referred to as “D”). The polymer was polyethylene A with a density of 0.957 g / cm3(ISO 1183), melt flow rates of 0.75 g / 10min (ISO 1133 190 °C / 2.16 kg) and 22 g / 1 Omin (ISO 1133, 190 °C / 21.6 kg), and a melting point of 135 °C.

[0431] The process involves collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet. The consolidated sheet was subsequently whole surface thermally bonded without substantial pressure, as reflected in Table 8. The whole surface thermally bonded sheet was cooled to a temperature of about 80 °C or below to obtain a cooled sheet.

[0432] The cooled sheets were subsequently passed between two rolls having interpenetrating blunt pins, each pin having a diameter of 1 mm and an upper edge radius of 0.25 mm. The blunt pins were separated by 3.3 mm center-to-center in MD direction and 3.2 mm center-to-center in XD direction at the point of interacting with the flash-spun sheets.

[0433] The flash spin sheets according to comparative examples CE8, CE9 and CE10 did not receive a step of thermally bonding without substantial pressure and cooling, nor a softening step.

[0434] The spinning, bonding, cooling and softening conditions and sheet properties are reported in Table 8, below.

[0435] Table 8: Summary of the sheet preparation of Comparative Examples CE8 to CE10 and Examples E20 to E24

[0436]

[0437]

[0438] * not applicable, ** not measured

[0439] The examples in Table 8 show the effect of embossing the whole surface bonded sheet with a rib pattern on both sides or a rib pattern on one side and a linen pattern on the other side, between a prior whole surface bonding step and a subsequent softening step. It is noted that the contact time for the whole surface bonding is in the range of 0.5 - 2 seconds, and the contact time for the embossing is in the range of about 8 to about 15 ms, meaning at least a factor 30 shorter.

[0440] The application of the additional embossing step results in a moderate change in physical properties such as tensile strength and elongation, but results in a notable increase in the surface robustness of the fabric, as can be seen from significantly higher crock values.

[0441] Additionally, the additional embossing step results in a reduction in the handle-o-meter values, meaning that the fabric becomes less stiff.

[0442] Moreover, this reduction in stiffness is not accompanied by any notable change in the hydrostatic head or particle filtration efficiency, whereas typically, a reduction in stiffness results in a reduction in barrier properties such as particle filtration efficiency and hydrostatic head.

[0443] Additionally, comparison with a fabric made with embossing a slightly consolidated sheet with embossing using a “rib” pattern on both sides, and subsequently softening it, showsthat the fabric of this invention has a high value of the handle-o-meter, higher average strength, while maintaining a good breathability and particle filtration efficiency.

[0444] Comparative examples CE8 to CE10, which did not receive a step of whole surface thermally bonding without substantial pressure and cooling, had a considerably lower tensile strength, lower handle-o-meter values, and lower crock values than examples E20 to E24.

[0445] The whole surface thermally bonded and softened or whole surface thermally bonded, embossed and softened fabrics have a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.6 to about 1.3.

[0446] Garment Examples G1 to G5

[0447] The bonded flash-spun sheets of Examples E2, E6, E16, E21 and E23 were used to prepare five different garments. In these examples, the garments were full body coveralls with elastic bands at the cuffs, ankles, and hood. Each garment was prepared by measuring, cutting, and sewing together bonded flash-spun sheets with a sewing machine using a 3-thread-overlock seam. The properties of the garments shown in Table 9 below were measured on the bonded flash-spun sheet of the garment, except for the seam strength which was measured on the seam of the garment.

[0448] Table 9: Summary of Garments G1 to G5.

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[0454]

[0455]

[0456] The garments have a good combination of mechanical properties such as trapezoidal tear resistance, puncture resistance, and abrasion, while combining good breathability (Ret) and good resistance to chemical permeation according to ISO 6529 against both sodium hydroxide and sulphuric acid, making them suitable for use in protective garment applications, particularly chemical protective garment applications.

[0457] OTHER EMBODIMENTS

[0458] 1. In some embodiments, the present application provides a thermally bonded sheet of nonwoven flash-spun plexifilamentary fibrils, the sheet having

[0459] (a) a basis weight from about 35 g / m2to about 58 g / m2,

[0460] (b) a Gurley Hill porosity of about 20 seconds or less,

[0461] (c) a particle filtration efficiency of about 90 % or more,

[0462] (d) a handle-o-meter stiffness from about 0.4 N to about 1.20 N,

[0463] (e) a delamination from about 0.1 N to about 1.0 N, and

[0464] (f) a Moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0465] 2. In some embodiments, the present application provides a thermally bonded sheet of nonwoven flash-spun plexifilamentary fibrils, the sheet having

[0466] (a) a basis weight from about 35 g / m2to about 58 g / m2,

[0467] (b) a Gurley Hill porosity of about 20 seconds or less,

[0468] (c) a particle filtration efficiency of about 90 % or more,

[0469] (d) a handle-o-meter stiffness from 0.5 N to about 1.20 N,

[0470] (e) a delamination from about 0.1 N to about 1.0 N, and

[0471] (f) a Moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0472] 3. The sheet of embodiment 1 or 2 having a basis weight from about 39 g / m2to about 58 g / m2, from about 40 g / m2to about 49 g / m2, from about 40 g / m2to about 44 g / m2or from about 44 g / m2to about 49 g / m2.

[0473] 4. The sheet of any of the preceding embodiments having a Gurley Hill porosity of about 15 seconds or less, of about 10 seconds or less, or of about 5 seconds or less.The sheet of any of the preceding embodiments having a Gurley Hill porosity of about 2 seconds to about 20 seconds, of about 2 seconds to about 15 seconds, of about 2 seconds to about 10 seconds, or of about 2 seconds to about 5 seconds.

[0474] The sheet of any of the preceding embodiments having a Gurley Hill porosity from about 10 seconds to about 20 seconds.

[0475] The sheet of any of the preceding embodiments having a Frazier porosity of about 0.3 m3 / m2 / min to about 3 m3 / m2 / min, or of about 0.3 m3 / m2 / min to about 1.5 m3 / m2 / min. The sheet of any of the preceding embodiments having a particle filtration efficiency of about 93 % or more, of about 95 % or more, of about 97 % or more, or of about 98 % or more.

[0476] The sheet of any of the preceding embodiments having a particle filtration efficiency from about 90.0 % to about 99.9 %, from about 93.0 % to about 99.9 %, from about 95.0 % to about 99.9 %, from about 95.0 % to about 99.5 %, from about 97.0 % to about 99.9 %, from about 97.0 % to about 99.0 %, or from about 98.0 % to about 99.9 %.

[0477] The sheet of any of the preceding embodiments having an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 6 % to about 19 %, from about 6 % to about 14 %, from about 7 % to about 12 %, from about 7 % to about 11 %, or from about 7 % to about 10 %.

[0478] The sheet of any of the preceding embodiments having an average elongation from about 6 % to about 19 %, from about 6 % to about 14 %, from about 7 % to about 12 %, from about 7 % to about 11 %, or from about 7 % to about 10 %.

[0479] The sheet of any of the preceding embodiments having an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 10 % to about 30 %, from about 15 % to about 30 %, or from about 20 % to about 30 %.

[0480] The sheet of any of the preceding embodiments having an average elongation from about 10 % to about 30 %, from about 15 % to about 30 %, or from about 20 % to about 30 %. The sheet of any of the preceding embodiments having an average tensile strength from about 70 N to about 180 N, from about 70 N to about 160 N, from about 90 N to about 160 N, or from about 70 N to about 130 N.

[0481] The sheet of any of the preceding embodiments having an average tensile strength from about 130 N to about 160 N.16. The sheet of any of the preceding embodiments having an average tensile strength, normalized to basis weight, from about 1.5 N / (g / m2) to about 4.0 N / (g / m2), from about 1.5 N / (g / m2) to about 3.6 N / (g / m2), or from about 1.5 N / (g / m2) to about 2.7 N / (g / m2).

[0482] 17. The sheet of any of the preceding embodiments having an average tensile strength, normalized to basis weight, from about 2.7 N / (g / m2) to about 3.6 N / (g / m2).

[0483] 18. The sheet of any of the preceding embodiments having a handle-o-meter stiffness from about 0.5 N to about 1.2 N, from about 0.5 N to about 1.0 N, from about 0.6 N to about 1.0 N, from about 0.6 N to about 0.8 N, or from about 0.4 N to about 1.0 N, or from about 0.4 N to about 0.8 N.

[0484] 19. The sheet of any of the preceding embodiments having a handle-o-meter stiffness from about 0.8 N to about 1.2 N, or from about 1.0 N to about 1.2 N.

[0485] 20. The sheet of any of the preceding embodiments having a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.2 to about 5, from about 0.33 to about 3, or from about 0.5 to about 2.

[0486] 21. The sheet of any of the preceding embodiments having a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.6 to about 1.5, from about 0.7 to about 1.4, from about 0.8 to about 1.25, or from about 0.9 to about 1.1.

[0487] 22. The sheet of any of the preceding embodiments having a handle-o-meter stiffness, normalized to (basis weight)3, of about 0.0004 N / (g / m2)3or above, of about 0.0005 N / (g / m2)3or above, or of about 0.0006 N / (g / m2)3or above.

[0488] 23. The sheet of any of the preceding embodiments a handle-o-meter stiffness, normalized to (basis weight)3, from about 0.0004 N / (g / m2)3to about 0.0015 N / (g / m2)3, from about 0.0005 N / (g / m2)3to about 0.0014 N / (g / m2)3, or from about 0.0006 N / (g / m2)3to about 0.0012 N / (g / m2)3.

[0489] 4. The sheet of any of the preceding embodiments having a delamination strength from about 0.2 N to about 0.7 N, from about 0.2 N to about 0.6 N, from about 0.2 N to about 0.5 N, or from about 0.2 N to about 0.4 N.

[0490] 5. The sheet of any of the preceding embodiments having a delamination strength from about 0.3 N to about 0.6 N, or from about 0.4 N to about 0.6 N.

[0491] 6. The sheet of any of the preceding embodiments having an abrasion surface resistance with a crock from 10 to 100 cycles, from 20 to 100 cycles, from 30 to 100 cycles, or from 40 cycles to 100 cycles.27. The sheet of any of the preceding embodiments having an abrasion surface resistance with a crock from 10 to 80 cycles, from 20 to 80 cycles, from 30 to 80 cycles, or from 40 cycles to 80 cycles.

[0492] 28. The sheet of any of the preceding embodiments having an abrasion surface resistance with a crock from 10 to 60 cycles, from 20 to 60 cycles, or from 30 to 80 cycles.

[0493] 29. The sheet of any of the preceding embodiments having an abrasion surface resistance with a crock from 10 to 40 cycles, from 20 to 40 cycles, or from 30 to 40 cycles.

[0494] 30. The sheet of any of the preceding embodiments having an abrasion surface resistance with a crock from 10 to 30 cycles.

[0495] 31. The sheet of any of the preceding embodiments having an abrasion surface resistance with a crock from 20 to 100 cycles, from 20 to 80, from 20 to 60 cycles, from 20 to 40 cycles, or from 20 to 30 cycles.

[0496] 32. The sheet of any of the preceding embodiments having a MVTR from about 8,000 g / m2 / day to about 30,000 g / m2 / day, from about 8,000 g / m2 / day to about 28,000 g / m2 / day, from about 10,000 g / m2 / day to about 26,000 g / m2 / day, from about 10,000 g / m2 / day to about 18,000 g / m2 / day, from about 10,000 g / m2 / day to about 16,000 g / m2 / day, or from about 10,000 g / m2 / day to about 14,000 g / m2 / day.

[0497] 33. The sheet of any of the preceding embodiments having a MVTR from about 12,000 g / m2 / day to about 30,000 g / m2 / day, from about 14,000 g / m2 / day to about 28,000 g / m2 / day, or from about 16,000 g / m2 / day to about 28,000 g / m2 / day.

[0498] 34. The sheet of any of the preceding embodiments having a Ret from about 2 m2Pa / W to about 10 m2Pa / W, from about 2 m2Pa / W to about 5 m2Pa / W, or from about 2 m2Pa / W to about 4 m2Pa / W.

[0499] 35. The sheet of any of the preceding embodiments having a Ret from about 3 m2Pa / W to about 8 m2Pa / W, from about 3 m2Pa / Wto about 6 m2Pa / W, from about 4 m2Pa / Wto about 6 m2Pa / W, or from about 3 m2Pa / W to about 5 m2Pa / W.

[0500] 36. The sheet of any of the preceding embodiments having a Ret from about 4 m2Pa / W to about 10 m2Pa / W, or from about 6 m2Pa / W to about 10 m2Pa / W.

[0501] 37. The sheet of any of the preceding embodiments having a thickness from about 150 pm to about 220 pm, or from about 160 pm to about 220 pm.

[0502] 38. The sheet of any of the preceding embodiments having a thickness from about 150 pm to about 200 pm, or from about 160 pm to about 200 pm, or having a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 10 wt% NaOH of60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above, and having a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0503] 39. The sheet of any of the preceding embodiments having a hydrostatic head from about 100 cmH2O to about 200 cmH2O, from about 110 cmH2O to about 200 cmH2O, from about 110 cmH2O to about 180 cmH2O, or from about 110 cmH2O to about 160 cmH2O.

[0504] 40. The sheet of any of the preceding embodiments having a hydrostatic head from about 120 cmH2O to about 180 cmH2O, from about 120 cmH2O to about 160 cmH2O, or from about 140 cmH2O to about 180 cmH2O.

[0505] 41. The sheet of any of the preceding embodiments, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a polyolefin.

[0506] 42. The sheet of embodiment 41 , wherein the polyolefin is selected from polyethylene (PE), polypropylene (PP), and blends / mixtures thereof.

[0507] 43. The sheet of embodiment 41 or 42, wherein the polyolefin is a high-density polyethylene (HDPE), a blend or mixture of a high-density polyethylene (HDPE) with low-density polyethylene (LDPE), or a blend or mixture of a high-density polyethylene (HDPE) with linear low-density polyethylene (LLDPE).

[0508] 44. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, and a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0509] 45. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an average tensile strength from about 70 N to about 180 N.The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a Moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an average tensile strength, normalized to basis weight, from about 1.5 N / (g / m2) to about 3.6 N / (g / m2). The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an abrasion surface resistance with a crock from 10 to about 100 cycles.

[0510] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2 to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, and an abrasion surface resistance with a crock from 10 to 100 cycles.

[0511] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %, and an abrasion surface resistance with a crock from 10 to 100 cycles.The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %, and an abrasion surface resistance with a crock from 10 to 100 cycles.

[0512] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Frazier air permeability from about 0.3 m3 / m2 / min to about 3 m3 / m2 / min), a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, an average tensile strength from about 70 N to about 180 N, an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %, and an abrasion surface resistance with a crock from 10 to 100 cycles.

[0513] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %.

[0514] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate(MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0515] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.7 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a moisture vaportransmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day.

[0516] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at leastone direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0517] 58. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.20 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 20 %.

[0518] 59. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0519] 60. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 39 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0520] 61. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 39 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 90 % to about 99.9 %, a handle-o-meter stiffness from about 0.4 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) fromabout 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 m to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 14 %.

[0521] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a moisture vaportransmission rate (MVTR) from about 8000 g / m2 / day to about 28,000 g / m2 / day.

[0522] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 94 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and a thickness from about 150 pm to about 210 pm.

[0523] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a moisture vaportransmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day.

[0524] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, and a Ret from about 2 m2Pa / W to about 8 m2Pa / W.

[0525] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hillporosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and a thickness from about 150 pm to about 210 pm.

[0526] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and a thickness from about 150 pm to about 210 pm.

[0527] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0528] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, adelamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0529] 71. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0530] 72. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0531] 73. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 19 %.

[0532] 74. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, adelamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0533] 75. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0534] 76. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), of from about 7 % to about 12 %.

[0535] 77. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), of from about 7 % to about 12 %. 78. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, adelamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0536] 79. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 20 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 12 %.

[0537] 80. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0538] 81. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 35 g / m2to about 58 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0539] 82. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 97 %to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0540] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0541] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 9000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Gurley Hill porosity from about 2 to about 10 seconds, a particle filtration efficiency from about 96 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 8 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0542] The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % toabout 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0543] 87. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0544] 88. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0545] 89. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 3 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / Wto about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0546] 90. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosityfrom about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0547] 91. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / Wto about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0548] 92. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.0 N, a delamination strength from about 0.2 N to about 0.6 N, a moisture vapor transmission rate (MVTR) from about 12,000 g / m2 / day to about 28,000 g / m2 / day, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0549] 93. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has a basis weight from about 38 g / m2to about 50 g / m2, a Frazier porosity from about 0.3 to about 1.5 m3 / m2 / min, a particle filtration efficiency from about 97 % to about 99.9 %, a handle-o-meter stiffness from about 0.6 N to about 1.2 N, a delamination strength from about 0.2 N to about 0.6 N, a Ret from about 2 m2Pa / Wto about 5 m2Pa / W, a thickness from about 150 pm to about 210 pm, a thickness from about 150 pm to about 210 pm, and an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 7 % to about 10 %.

[0550] 94. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene,and the sheet has an average trapezoidal tear strength from about 10 N to about 50 N, from about 10 N to about 40 N, from about 10 N to about 30 N, from about 15 N to about 30 N, or from about 20 N to about 30 N, and / or the sheet has an opacity of about 90 % or more, of about 93 % or more, of about 95 % or more, or of about 97 % or more, from about 90 % to about 99 %, from 90 % about to about 97 %, from about 93 % to about 97 %, from about 95 % to about 99 %, or from about 95 % to about 97 %.

[0551] 95. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has an average puncture resistance from about 10 N to about 30 N, from about 10 N to about 25 N, or from about 12 N to about 25 N.

[0552] 96. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has an average puncture resistance from about 10 N to about 25 N, a resistance to chemical permeation, BTi0, measured according to ISO 6529 against 10 wt% NaOH of 120 min or above, or of 240 min or above, and a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 18 wt% H2SO4of 120 min or above, or of 240 min or above.

[0553] 97. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has an average trapezoidal tear strength from about 10 N to about 40 N, a resistance to chemical permeation, BTi0, measured according to ISO 6529 against 10 wt% NaOH of 120 min or above, or of 240 min or above, and a resistance to chemical permeation, BTi0, measured according to ISO 6529 against 18 wt% H2SO4of 120 min or above, or of 240 min or above.

[0554] 98. The sheet of any of the preceding embodiments 1 to 43, wherein the flash-spun plexifilamentary fibrils of the bonded sheet are comprised of a high-density polyethylene, and the sheet has an average trapezoidal tear strength from about 10 N to about 40 N, a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH of 120 min or above, or of 240 min or above, a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 18 wt% H2SO4of 120 min or above, or of 240 min or above, and an average abrasion resistance of 10 rubs or above, of 40 rubs or above, of 100 rubs or above, of 400 rubs or above, of 1000 rubs or above, or of 2000 rubs or above.

[0555] 99. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:(i) generating a spin fluid comprising

[0556] (a) from about 8 to about 12 weight percent of a polymer, and

[0557] (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,

[0558] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (Hi) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0559] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0560] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and

[0561] (vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

[0562] A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0563] (i) generating a spin fluid comprising

[0564] (a) from about 8 to about 12 weight percent of a polymer, and

[0565] (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1, 2-dichloroethylene, trans-1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,

[0566] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0567] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,

[0568] (vi) embossing the cooled sheet to obtain an embossed sheet, and

[0569] (vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0570] 101. The process of any of the preceding embodiments 99 to 100, wherein the spin fluid comprises the polymer in an amount from about 8.0 to about 12.0 weight percent, based on the total amount of the spin fluid, or in an amount from about 8.0 to about 11.5 weight percent, based on the total amount of the spin fluid, or in an amount from about 8.0 to about 11.0 weight percent, based on the total amount of the spin fluid, or in an amount from about 8.0 to about 10.5 weight percent, based on the total amount of the spin fluid, or in an amount from about 8.0 to about 10.0 weight percent, based on the total amount of the spin fluid, or in an amount from about 8.5 to about 11.5 weight percent, based on the total amount of the spin fluid, or in an amount from about 9.0 to about 11.0 weight percent, based on the total amount of the spin fluid.

[0571] 102. The process of any of the preceding embodiments 99 to 101, wherein the flashspinning is performed at a temperature from about 195 °C to about 230 °C, from about 200 °C to about 220 °C, from about 205 °C to about 220 °C, or from about 210 °C to about 220 °C.

[0572] 103. The process of any of the preceding embodiments 99 to 102, wherein the spin agent comprises a chlorine-containing solvent, selected from dichloromethane, cis-1 ,2- dichloroethylene, trans-1 ,2-dichloroethylene, or a mixture of cis-1 ,2-dichloroethylene and trans-1,2-dichloroethylene, in combination with a fluorine-containing solvent which is a linear hydrofluorocarbon having three to six carbon atoms, a cyclic hydrofluorocarbon having four to five carbon atoms, a perfluorocarbon having five to six carbon atoms, or a hydrofluoroether.

[0573] 104. The process of embodiment 103, wherein the linear hydrofluorocarbons having three to six carbon atoms of the spin agent is selected from 1 ,1 ,1 ,3,3-pentafluorobutane, 1 H,4H- octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H- dodecafluorohexane.The process of embodiment 103 or 104, wherein the spin agent comprises, consists essentially, or consists of a mixture of (1) dichloromethane and (2) 1 , 1 ,1 , 3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1 H,6H-dodecafluorohexane, or wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent dichloromethane and (2) from about 15 to about 30 weight percent 1 , 1 ,1 , 3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1 H,6H-dodecafluorohexane, or wherein the spin agent comprises, consists essentially, or consists of (1) from about 75 to about 85 weight percent dichloromethane and (2) from about 15 to about 25 weight percent 1 , 1 ,1 , 3,3-pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H-tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0574] The process of embodiment 103, wherein the cyclic hydrofluorocarbons having four to five carbon atoms is selected from cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1 , 1 ,2, 2,3,3-hexafluorocyclopentane.

[0575] The process of embodiment 103 or 106, wherein the spin agent comprises, consists essentially, or consists of a mixture of (1) dichloromethane and (2) cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans- 1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1,1,2,2,3,3-hexafluorocyclopentane

[0576] The process of embodiment 107, wherein the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 80 weight percent dichloromethane and (2) from about 20 to about 35 weight percent cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1 , 1 ,2, 2,3,3-hexafluorocyclopentane,

[0577] The process of embodiment 107 or 108, wherein the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 75 weight percent dichloromethane and (2) from about 25 to about 35 weight percent cis-1H,2H-octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H-octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3-hexafluorocyclopentane.110. The process of embodiment 107, wherein the spin agent comprises, consists essentially, or consists of a mixture of (1) 1,2-dichloroethylene and (2) 1,1, 1,3, 3- pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H- tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0578] 111. The process of embodiment 110, wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent 1,2- dichloroethylene and (2) from about 15 to about 30 weight percent 1,1, 1,3, 3- pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H- tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0579] 112. The process of embodiment 111, wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 80 weight percent 1,2- dichloroethylene and (2) from about 20 to about 30 weight percent 1,1, 1,3, 3- pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H- tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0580] 113. The process of embodiment 107, the spin agent comprises, consists essentially, or consists of a mixture of (1) 1,2-dichloroethylene and (2) cis-1H,2H- octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H- octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H- heptafluorocyclopentane, or 1,1,2,2,3,3-hexafluorocyclopentane.

[0581] 114. The process of embodiment 113, wherein the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 80 weight percent 1,2- dichloroethylene and (2) from about 20 to about 35 weight percent cis-1H,2H- octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H- octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H- heptafluorocyclopentane or 1,1,2,2,3,3-hexafluorocyclopentane.

[0582] 115. The process of embodiment 114, wherein the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 75 weight percent 1,2- dichloroethylene and (2) from about 20 to about 30 weight percent cis-1H,2H- octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H- octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H- heptafluorocyclopentane, or 1,1,2,2,3,3-hexafluorocyclopentane.

[0583] 116. The process of embodiment 107, wherein the spin agent comprises, consists essentially, or consists of a mixture of (1) trans- 1,2-dichloroethylene and (2) 1, 1,1, 3,3- pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H- tridecafluorohexane, or 1H,6H-dodecafluorohexane.117. The process of embodiment 116, wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent trans-1,2- dichloroethylene and (2) from about 15 to about 30 weight percent 1,1, 1,3, 3- pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H- tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0584] 118. The process of embodiment 117, wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 80 weight percent trans-1,2- dichloroethylene and (2) from about 20 to about 30 weight percent 1,1, 1,3, 3- pentafluorobutane, 1H,4H-octafluorobutane, 2H,3H-decafluoropentane, 1H- tridecafluorohexane, or 1H,6H-dodecafluorohexane.

[0585] 119. The process of embodiment 107, wherein the spin agent comprises, consists essentially, or consists of a mixture of (1) trans-1,2-dichloroethylene and (2) 1H,2H- octafluorocyclopentane, cis-1H,2H-octafluorocyclopentane, trans-1H,2H- octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3- hexafluorocyclopentane.

[0586] 120. The process of embodiment 119, wherein the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 80 weight percent trans-1,2- dichloroethylene and (2) from about 20 to about 35 weight percent cis-1H,2H- octafluorocyclopentane, trans-1H,2H-octafluorocyclopentane, a mixture of cis-1H,2H- octafluorocyclopentane and trans-1H,2H-octafluorocyclopentane, 1H,1H,2H- heptafluorocyclopentane, or 1,1,2,2,3,3-hexafluorocyclopentane.

[0587] 121. The process of embodiment 120, wherein the spin agent comprises, consists essentially, or consists of (1) from about 65 to about 75 weight percent trans- 1,2- dichloroethylene and (2) from about 20 to about 30 weight percent 1H,2H- octafluorocyclopentane, cis-1H,2H-octafluorocyclopentane, trans-1H,2H- octafluorocyclopentane, 1H,1H,2H-heptafluorocyclopentane, or 1, 1,2, 2,3,3- hexafluorocyclopentane.

[0588] 122. The process of embodiment 103, wherein the hydrofluoroether is selected from 1- methoxynonafluorobutane or 1 -ethoxynonafluorobutane.

[0589] 123. The process of embodiment 103 or 122, wherein the spin agent comprises, consists essentially, or consists of a mixture of (1) dichloromethane and (2) 1- methoxynonafluorobutane or 1 -ethoxynonafluorobutane.

[0590] 124. The process of embodiment 123, wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 85 weight percent dichloromethaneand (2) from about 15 to about 30 weight percent 1 -methoxynonafluorobutane or 1- ethoxynonafluorobutane.

[0591] 125. The process of embodiment 124, wherein the spin agent comprises, consists essentially, or consists of (1) from about 70 to about 80 weight percent dichloromethane and (2) from about 20 to about 30 weight percent 1 -methoxynonafluorobutane or 1- ethoxynonafluorobutane.

[0592] 126. The process of any of embodiments 99 to 125, wherein the flash-spinning is performed at a temperature from about 195 °C to about 230 °C, from about 200 °C to about 220 °C, from about 205 °C to about 230 °C, or from about 210 °C to about 220 °C, and wherein the spin fluid comprises about 8.0 to about 11.0 weight percent polymer based on the total amount of the spin fluid.

[0593] 127. The process of any of embodiments 99 to 126, wherein the flash-spinning is performed at a temperature from about 205 °C to about 230 °C, or from about 210 °C to about 220 °C, and wherein the spin fluid comprises about 8.0 to about 10.5 weight percent polymer based on the total amount of the spin fluid.

[0594] 128. The process of any of embodiments 99 to 127, wherein the flash-spinning is performed at a temperature from about 205 °C to about 230 °C, or from about 210 °C to about 220 °C, and wherein the spin fluid comprises about 8.0 to about 10.0 weight percent polymer based on the total amount of the spin fluid.

[0595] 129. The process of any of embodiments 99 to 128, wherein the flash-spinning is performed at a temperature from about 205 °C to about 230 °C, or from about 210 °C to about 220 °C, and wherein the spin fluid comprises about 9.0 to about 11.0 weight percent polymer based on the total amount of the spin fluid.

[0596] 130. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0597] (i) generating a spin fluid comprising

[0598] (a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and

[0599] (b) a spin agent comprising one or more hydrocarbons,

[0600] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0601] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and

[0602] (vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

[0603] 131. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:

[0604] (i) generating a spin fluid comprising

[0605] (a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and

[0606] (b) a spin agent comprising one or more hydrocarbons,

[0607] (ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,

[0608] (iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,

[0609] (v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,

[0610] (vi) embossing the cooled sheet to obtain an embossed sheet, and

[0611] (vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0612] 132. The process of embodiment 130 or 131 , wherein the spin fluid comprises the polymer in an amount of from about 12.0 to about 18.0 weight percent, based on the total amount of the spin fluid, or from about 14.0 to about 18.0 weight percent, based on the total amount of the spin fluid, or from about 15.0 to about 17.0 weight percent, based on the total amount of the spin fluid.133. The process of any of embodiments 130 to 132, wherein the flash-spinning is performed at a temperature of 195 °C or above, or a temperature of 200 °C or above, or a temperature of 205 °C or above, or a temperature of 210 °C or above.

[0613] 134. The process of any of embodiments 130 to 133, wherein the flash-spinning is performed at a temperature from about 195 °C to about 220 °C, or from about 190 °C to about 200 °C.

[0614] 135. The process of any of embodiments 130 to 134, wherein the one or more hydrocarbons of the spin agent are selected from n-pentane, cyclopentane, hexane, cyclohexane, 2- methylbutane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, or mixtures thereof.

[0615] 136. The process of any of embodiments 130 to 135, wherein the spin agent comprises n- pentane, cyclopentane, or a mixture thereof.

[0616] 137. The process of any of embodiments 130 to 136, wherein the spin agent comprises, consists essentially of or consists of n-pentane.

[0617] 138. The process of any of embodiments 130 to 137, wherein the spin agent comprises, consists essentially of or consists of a mixture of n-pentane and cyclopentane.

[0618] 139. The process of embodiment 138, wherein the spin agent comprises, consists essentially of, or consists of from about 60 to about 90 weight percent n-pentane and from about 40 to about 10 weight percent cyclopentane, or from about 60 to about 80 weight percent n-pentane and from about 40 to about 20 weight percent cyclopentane.

[0619] 140. The process of embodiments 130 to 136, wherein the spin agent comprises or consists essentially of a mixture of n-pentane, cyclopentane, and a branched hydrocarbon with 5 or 6 carbon atoms.

[0620] 141. The process of embodiment 140, wherein the spin agent comprises, consists essentially of, or consist of a mixture of (1) n-pentane, (2) cyclopentane, and (3) 2- methylbutane, 2-methylpentane, 3-methylpentane, or 2,2-dimethylbutane.

[0621] 142. The process of any of embodiments 140 to 141 , wherein the spin agent comprises, consists essentially of, or consist of a mixture of (1) from about 60 to about 85 weight percent n-pentane, (2) from about 13 to about 33 weight percent cyclopentane, and (3) from about 2 to about 7 weight percent 2,2-dimethylbutane, 2-methylpentane, 3- methylpentane, or 2,2-dimethylbutane.

[0622] 143. The process of any of embodiments 130 to 142, wherein the plexifilamentary fibrils are flash-spun at a spin temperature from about 190 °C to about 205 °C using a spin fluidcomprising about 12.0 to about 19.0 weight percent polymer, based on the total amount of the spin fluid, and comprising a spin agent which comprises, consists essentially of, or consists of n-pentane.

[0623] The process of any of embodiments 130 to 142, wherein the plexifilamentary fibrils are spun at a spin temperature from about 195 °C to about 205 °C using a spin fluid comprising about 14.0 to about 19.0 weight percent polymer, based on the total amount of the spin fluid, and comprising a spin agent which comprises, consists essentially of, or consists of n-pentane.

[0624] The process of any of embodiments 130 to 142, wherein the plexifilamentary fibrils are spun using a spin fluid comprising about 12.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid, and at a spin temperature of about 195 °C or more, or about 200 °C or more, or about 205 °C or more, or about 210 °C or more. The process of any of embodiments 130 to 142, wherein the plexifilamentary fibrils are spun using a spin fluid comprising about 14.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid, and at a spin temperature of about 195 °C or more, or about 200 °C or more, or about 205 °C or more, or about 210 °C or more. The process of any of embodiments 130 to 142, wherein the plexifilamentary fibrils are spun using a spin fluid comprising about 15.0 to about 17.0 weight percent polymer, based on the total amount of the spin fluid, and at a spin temperature of about 195 °C or more, or about 200 °C or more, or about 205 °C or more, or about 210 °C or more. The process of any of embodiments 130 to 142, wherein the plexifilamentary fibrils are spun at a spin temperature from about 195 °C to about 205 °C using a spin fluid comprising about 14.0 to about 18.0 weight percent polymer, based on the total amount of the spin fluid.

[0625] The process of any one of embodiments 99 to 148, wherein at least one side of the cooled sheet is embossed.

[0626] The process of any one of embodiments 99 to 149, wherein the embossing roll(s) apply a pressure during bonding from about 150 kPa to about 750 kPa.

[0627] The process of any one of embodiments 99 to 150, wherein the cooled sheet is embossed on both sides using the same pattern.

[0628] The process of embodiment 151, wherein the cooled sheet is embossed on both sides using a point pattern, or the cooled sheet is embossed on both sides using a rib pattern, or the cooled sheet is embossed on both sides using a linen pattern.153. The process of any one of embodiments 99 to 150, wherein the cooled sheet is embossed on both sides using different patterns.

[0629] 154. The process of embodiment 153, wherein the cooled sheet is embossed on one side using a point pattern and on another side using a rib pattern, or the cooled sheet is embossed on one side using a point pattern and on another side using a linen pattern, or the cooled sheet is embossed on one side using a rib pattern and on another side using a linen pattern.

[0630] 155. The process of any one of embodiments 99 to 154, wherein in the mechanical softening step, each interpenetrating pin is a blunt pin 10 that includes at least a distal end 12 that has a blunt surface 15 and a shaft that has a surface 14.

[0631] 156. The process of embodiment 155, wherein the edges 17 of the shaft 14 are parallel, tapered toward the distal end 12, or a combination thereof.

[0632] 157. The process of any one of embodiments 155 to 156, wherein the cross-section of the shaft 14 is a regular or irregular polygon.

[0633] 158. The process of embodiments 157, wherein the cross-section of the shaft 14 is a rectangle, a pentagon, a hexagon, or an octagon.

[0634] 159. The process of any one of embodiments 155 to 156, wherein the cross-section of the shaft 14 is round, including a circle or an oval.

[0635] 160. The process of any one of embodiments 155 to 159, wherein the blunt surface 15 is flat and has the shape of a regular or irregular polygon, including a rectangle, a pentagon, a hexagon, or an octagon.

[0636] 161. The process of any one of embodiments 155 to 159, wherein the blunt surface 15 is round or oval.

[0637] 162. The process of any one of embodiments 155 to 161, wherein the blunt pins 10 have a cylindrical shape with a circular cross-section at the proximal end 11 , wherein the crosssection at the proximal end 11 has a diameter from about 0.8 mm to about 1.8 mm, and wherein the distal end 12 of the blunt pins 10 has a blunt surface having a diameter of from about 0.6 mm to about 1.6 mm.

[0638] 163. The process of any one of embodiments 155 to 162, wherein the blunt pins 10 are separated by about 1.5 mm to about 5.0 mm center-to center in the machine direction (MD) and by about 1.5 mm to about 5.0 mm center-to center in the transverse direction (XD) direction.

[0639] 164. The process of any one of embodiments 99 to 163, wherein the obtained sheet has(a) a basis weight from about 35 g / m2to about 58 g / m2,

[0640] (b) a Gurley Hill porosity of about 20 seconds or less,

[0641] (c) a particle filtration efficiency of about 90 % or more,

[0642] (d) a handle-o-meter stiffness from about 0.4 N to about 1.20 N,

[0643] (e) a delamination strength from about 0.1 N to about 1.0 N, and

[0644] (f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

[0645] 165. The process of one of embodiments 99 to 164, wherein the polymer is a polyolefin, selected from the group of polyethylene (PE), polypropylene (PP), and blends / mixtures thereof,

[0646] 166. The process of one of embodiments 99 to 165, wherein the polymer is a polyolefin, and wherein said polyolefin is a high-density polyethylene (HDPE), a blend of a high- density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE), or a blend of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE).

[0647] 167. A sheet of nonwoven flash-spun plexifilamentary fibrils obtainable by the process of any one of embodiments 99 to 166.

[0648] 168. A thermally bonded sheet of nonwoven flash-spun plexifilamentary fibrils, the sheet having

[0649] (a) a basis weight from about 35 g / m2to about 58 g / m2,

[0650] (b) a Gurley Hill porosity of about 20 seconds or less,

[0651] (c) a particle filtration efficiency of about 90 % or more,

[0652] (d) a handle-o-meter stiffness from about 0.4 N to about 1.20 N,

[0653] (e) a delamination strength from about 0.1 N to about 1.0 N, and

[0654] (f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day,

[0655] wherein the sheet is obtained by the process of any one of embodiments 99 to 166.

[0656] 169. A sheet of nonwoven flash-spun plexifilamentary fibrils obtainable by the process of any one of embodiments 99 to 166.

[0657] 170. A multilayer structure comprising at least one sheet according to any one of embodiments 1 to 98 and at least one further sheet or film.

[0658] 171. Use of a sheet of any of embodiments 1 to 98 for preparing a multilayer structure. 172. Use of a sheet of any one of embodiments 1 to 98 or of the multilayer structure of embodiment 170 for the production of packaging.173. An article comprising a sheet of any one of embodiments 1 to 98 or a multilayer structure of embodiment 170.

[0659] 174. The article of embodiment 173, wherein the article is selected from active packages, car covers, cargo covers, mattress covers, industrial bags, consumer bags, garments, and medical packages.

[0660] 175. The article of embodiment 174, wherein the article is a protective garment.

[0661] 176. The protective garment of embodiment 175, comprising a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene, wherein the garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

[0662] 177. A protective garment comprising a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene, wherein the garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

[0663] 178. The protective garment of any of embodiments 176 to 177 having a basis weight from about 38 g / m2to about 58 g / m2, from about 38 g / m2to about 49 g / m2, from about 40 g / m2to about 49 g / m2, from about 38 g / m2to about 44 g / m2, from about 40 g / m2to about 44 g / m2, or from about 44 g / m2to about 49 g / m2.

[0664] 179. The protective garment of any of embodiments 176 to 178 having a Ret from about 3 m2Pa / W to about 8 m2Pa / W, from about 3 m2Pa / W to about 6 m2Pa / W, from about 4 m2Pa / W to about 6 m2Pa / W, or from about 3 m2Pa / W to about 5 m2Pa / W.

[0665] 180. The protective garment of any of embodiments 176 to 179 having a handle-o-meter stiffness from about 0.05 N to about 1.2 N, from about 0.1 N to about 1.2 N, from about 0.2 N to about 1.2 N, from about 0.3 N to about 1.0 N, from about 0.4 N to about 1.0 N, from about 0.3 N to about 0.8 N, from about 0.3 N to about 0.6 N, from about 0.4 N to about 0.6 N, from about 0.05 to about 0.6 N, from about 0.05 N to about 0.5 N, from about 0.1 to about 0.5 N, from about 0.1 to about 0.4 N, or from about 0.1 N to about 0.3 N. 181. The protective garment of any of embodiments 176 to 180 having an average tensile strength from about 70 N to about 180 N, from about 70 N to about 160 N, from about 90 N to about 160 N, from about 70 N to about 130 N, or from about 130 N to about 160 N.182. The protective garment of any of embodiments 176 to 181 having an average seam strength from about 50 N to about 300 N, from about 50 N to about 200 N, from about 75 N to about 200 N, from about 75 N to about 150 N, or from about 75 N to about 125 N.

[0666] 183. The protective garment of any of embodiments 176 to 182 having an average trapezoidal tear strength from about 10 N to about 40 N, from about 10 N to about 30 N, from about 15 N to about 30 N, or from about 20 N to about 30 N.

[0667] 184. The protective garment of any of embodiments 176 to 183 having an average puncture resistance from about 10 N to about 30 N, from about 10 N to about 25 N, or from about 12 N to about 25 N.

[0668] 185. The protective garment of any of embodiments 176 to 184 having an average abrasion resistance of 10 rubs or above, 40 rubs or above, of 100 rubs or above, of 400 rubs or above, of 1000 rubs or above, or of 2000 rubs or above.

[0669] 186. The protective garment of any of embodiments 176 to 185 having a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above. 187. The protective garment of any of embodiments 176 to 186 having a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above. 188. The protective garment of any of embodiments 176 to 187 having a resistance to chemical permeation measured, BT1>0, according to ISO 6529 against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above. 189. The protective garment of any of embodiments 176 to 188 having a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 30 wt% H2SO4of 60 min or above, or of 120 min or above, or of 240 min or above, or of 480 min or above.

[0670] 190. The protective garment of any of embodiments 176 to 189 having a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 10 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above and having a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0671] 191. The protective garment of any of embodiments 176 to 190 having a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above and having a resistance to chemical permeation, BTi.o, measured according to ISO 6529against 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0672] 192. The protective garment of any of embodiments 176 to 191 having an average Type 5 inward leakage of 10 % or less, of 5 % or less, of 3 % or less, of 2 % or less, or of 1 % or less.

[0673] 193. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 10 wt% NaOH or against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0674] 194. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BT1)0, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0675] 195. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0676] 196. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.197. The protective garment of any of the preceding embodiments 193 to 196 having a handle-o-meter stiffness from about 0.05 N to about 0.6 N, from about 0.1 N to about 0.5 N, or from about 0.2 N to about 0.4 N.

[0677] 198. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 30 N, and a resistance to chemical permeation, BTi,01measured according to ISO 6529 against 10 wt% NaOH or against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0678] 199. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 30 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0679] 200. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 30 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, of 480 min or above.

[0680] 201. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 30 N, and a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4 of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0681] 202. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistancefrom about 10 N to about 25 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10wt% NaOH or against 40 wt% NaOH of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0682] 203. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 18 wt% H2SO4or 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0683] 204. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, and a resistance to chemical permeation, BTi.o, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0684] 205. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, and a resistance to chemical permeation, BTij0, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

[0685] 206. The protective garment of any of the preceding embodiments 198 to 205 having a handle-o-meter stiffness from about 0.05 N to about 0.6 N, from about 0.1 N to about 0.5 N, or from about 0.2 N to about 0.4 N.

[0686] 207. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 10 N to about 30 N, an average puncture resistance from about 12 N to about 20 N, and an average Type 5 inward leakage of 5 % or less.

[0687] 208. The protective garment of embodiment 200, having a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about15 N to about 30 N, an average puncture resistance from about 12 N to about 20 N, an average abrasion resistance of 400 rubs or above, an average Type 5 inward leakage of 5 % or less, and a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 120 min or above.

[0688] 209. The protective garment of embodiment 201 , having a basis weight from about 38 g / m2to about 44 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 75 N to about 150 N, an average trapezoidal tear strength from about 15 N to about 30 N, an average puncture resistance from about 12 N to about 20 N, an average abrasion resistance of 1000 rubs or above, an average Type 5 inward leakage of 5 % or less, and a resistance to chemical permeation, BT-i.o, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 120 min or above.

[0689] 210. The protective garment of any of the preceding embodiments 207 to 209 having a handle-o-meter stiffness from about 0.05 N to about 0.6 N, from about 0.1 N to about 0.5 N, or from about 0.2 N to about 0.4 N

[0690] 211. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 50 N to about 150 N, an average trapezoidal tear strength from about 15 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, an average abrasion resistance of 400 rubs or above, an average tensile strength from about 70 N to about 180 N, or from about 90 N to about 160 N, and a resistance to chemical permeation, BT1 ,0, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 120 min or above.

[0691] 212. The protective garment of any of the preceding embodiments 176 to 192 having a basis weight from about 38 g / m2to about 49 g / m2, a Ret from about 2 m2Pa / W to about 5 m2Pa / W, an average seam strength from about 50 N to about 150 N, an average trapezoidal tear strength from about 15 N to about 30 N, an average puncture resistance from about 10 N to about 25 N, an average abrasion resistance of 1000 rubs or above, an average tensile strength from about 70 N to about 180 N or from about 90 N to about 160 N and a resistance to chemical permeation, BTi,0, measured according to ISO 6529 against 40 wt% NaOH and against 30 wt% H2SO4of 120 min or above.

[0692] 213. The protective garment of any of the preceding embodiments 211 to 212 having a handle-o-meter stiffness from about 0.05 N to about 0.6 N, from about 0.1 N t...

Claims

1. CLAIMS1. A thermally bonded sheet of nonwoven flash-spun plexifilamentary fibrils, the sheet having(a) a basis weight from about 35 g / m2to about 58 g / m2,(b) a Gurley Hill porosity of about 20 seconds or less,(c) a particle filtration efficiency of about 90 % or more,(d) a handle-o-meter stiffness from 0.5 N to about 1.20 N,(e) a delamination strength from about 0.1 N to about 1.0 N, and(f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

2. The sheet of claim 1 having an Ret value from about 2 to about 10 m2Pa / W.

3. The sheet of claim 1 or 2 having a thickness from about 150 to about 220 pm.

4. The sheet of any one of claims 1 to 3 having an elongation in at least one direction, selected from the machine direction (MD) and the transverse direction (XD), from about 6% to about 19 %.

5. The sheet of any one of claims 1 to 4 having an average tensile strength from about 70 N to about 180 N.

6. The sheet of any one of claims 1 to 5 having a ratio of the handle-o-meter stiffness in machine direction (MD) to the handle-o-meter stiffness in transverse direction (XD) from about 0.2 to about 5.

7. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:(i) generating a spin fluid comprising(a) from about 8 to about 12 weight percent of a polymer, and (b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,(ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,(v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and(vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

8. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:(i) generating a spin fluid comprising(a) from about 8 to about 12 weight percent of a polymer, and(b) a spin agent comprising a chlorine-containing solvent, selected from dichloromethane, cis-1,2-dichloroethylene, trans- 1 ,2-dichloroethylene, ora mixture of cis-1 ,2-dichloroethylene and trans-1 ,2-dichloroethylene, in combination with a fluorine-containing solvent,(ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,(v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,(vi) embossing the cooled sheet to obtain an embossed sheet, and(vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed ofthe embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

9. The process of claim 7 or 8, wherein the spin fluid comprises from about 9 to about 11 weight percent of a polymer, or wherein the temperature in step (ii) is at or above about 205 °C.

10. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:(i) generating a spin fluid comprising(a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and(b) a spin agent comprising one or more hydrocarbons,(ii) flash spinning the spin fluid at a temperature at or above about 190 °C and at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,(v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet, and(vi) mechanically softening the cooled sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils by passing it through one or more nips between rolls driven at substantially the same speed as the speed of the cooled sheet, wherein each roll has interpenetrating pins and rotates in the opposite direction as the other roll, and wherein each interpenetrating pin is a blunt pin.

11. A process for the preparation of a sheet of nonwoven flash-spun plexifilamentary fibrils which comprises the steps of:(i) generating a spin fluid comprising(a) from about 12 to about 18 weight percent of a polymer, based on the total amount of the spin fluid, and(b) a spin agent comprising one or more hydrocarbons,(ii) flash spinning the spin fluid at a temperature at or above about 190 °C at a pressure that is above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer, (iii) collecting the plexifilamentary fibrils of the polymer on a collecting means as a sheet of nonwoven flash-spun plexifilamentary fibrils and applying pressure to the sheet to obtain a consolidated sheet,(iv) thermally bonding the consolidated sheet by surface bonding without substantial pressure to obtain a bonded sheet,(v) cooling the bonded sheet to a temperature of about 80 °C or below to obtain a cooled sheet,(vi) embossing the cooled sheet to obtain an embossed sheet, and(vii) mechanically softening the embossed sheet by passing it through one or more nips between rotating rolls driven at substantially the same speed as the speed of the embossed sheet to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

12. The process of claim 10 or 11, wherein the spin agent comprises n-pentane, cyclopentane, or a mixture thereof.

13. The process of any one of claims 7 to 12, wherein the polymer is a polyolefin, selected from the group of polyethylene (PE), polypropylene (PP), and blends / mixtures thereof, or wherein the polymer is a polyolefin, wherein said polyolefin is a high-density polyethylene (HDPE), a blend of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE), or a blend of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE).

14. The process of any one of claims 7 to 13, wherein the obtained sheet has(a) a basis weight from about 35 g / m2to about 58 g / m2,(b) a Gurley Hill porosity of about 20 seconds or less,(c) a particle filtration efficiency of about 90 % or more,(d) a handle-o-meter stiffness from 0.5 N to about 1.20 N,(e) a delamination strength from about 0.1 N to about 1.0 N, and(f) a moisture vapor transmission rate (MVTR) from about 8000 g / m2 / day to about 30,000 g / m2 / day.

15. A sheet of nonwoven flash-spun plexifilamentary fibrils obtainable by the process of any one of claims 7 to 14.

16. A multilayer structure comprising at least one sheet according to any one of claims 1 to 6 or 15 and at least one further sheet or film.

17. Use of the sheet of any one of claims 1 to 6 or 15 for preparing a multilayer structure.

18. Use of a sheet of any one of claims 1 to 6 or 15 or of the multilayer structure of claim 16 for the production of garments.

19. An article comprising a sheet of any one of claims 1 to 6 or 15 or a multilayer structure of claim 16.

20. The article of claim 19, wherein the article is selected from active packages, car covers, cargo covers, mattress covers, industrial bags, consumer bags, garments, and medical packages.

21. The article of claim 20 which is a protective garment, said protective garment comprising a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene according to any of claims 1 to 6, wherein the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

22. A protective garment comprising a bonded sheet of flash-spun plexifilamentary fibrils of polyethylene, wherein the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 300 N, and an average trapezoidal tear strength from about 10 N to about 50 N.

23. A protective garment according to claim 21 or 22, wherein the protective garment has a basis weight from about 35 g / m2to about 58 g / m2, a Ret from about 2 m2Pa / W to about 10 m2Pa / W, an average seam strength from about 50 N to about 200 N, an average trapezoidal tear strength from about 10 N to about 40 N, and a resistance to chemical permeation, BT1j0, measured according to ISO 6529 against 10 wt% NaOH and against 18 wt% H2SO4of 60 min or above, of 120 min or above, of 240 min or above, or of 480 min or above.

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