Package comprising sealed contact area including nonwoven material having bonded surface with embossed impression pattern

Abstract

To provide an improved package for providing an enclosed interior environment capable of being sterilized and a gas permeable fibrous nonwoven sheet structure suitable for use therein.SOLUTION: This invention relates to a package for providing an enclosed interior environment capable of being sterilized, and a gas permeable fibrous nonwoven sheet structure which is useful in such a structure and has at least one surface having a pre-sealed, embossed impression pattern and a particle barrier penetration of below 10%, a Gurley Hill porosity of 40 seconds or less, and a steam transmission rate of 3500 g / m2 / day or greater.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to improved packaging for providing an enclosed internal environment which can be sterilized, and gas permeable fibrous nonwoven sheet structures suitable for use therein. [Background technology]

[0002] U.S. Pat. No. 6,034,008 to Lim et al. discloses a sheet material suitable for use in filtration and sterilization packaging that has strength, weight and barrier properties at least equivalent to those of TYVEK® spunbond olefin nonwoven sheet material traditionally used for such applications, but also has significantly improved air and liquid permeability.

[0003] In particular, Lim et al. disclose a full surface bonded "hard construction" product with a smooth paper feel that is commonly used for several applications, including sterile packaging, and a point bonded and softened "soft construction" product with a more fabric-like feel for apparel applications.

[0004] As disclosed by Lim et al., it is believed that the full surface bonding of the "hard-structured" flash-spun sheet product causes the high surface area plexifilamentary fibers of the sheet to shrink, which in turn causes the pores between the fibers to open up. Thus, "hard-structured" sheet products generally have higher water vapor transmission rates and higher hydrostatic head values ​​compared to "soft-structured" sheet products. This more permeable material has been found to have great utility in sterilization packaging materials, where the increased permeability allows the material to perform its function in a more efficient manner.

[0005] Fibrous nonwoven sheets are useful in packages that can be sterilized because they allow a manufacturer to first package the items and then sterilize the items in the package using a gas, such as steam, ethylene oxide, or some combination thereof. The sterilizing gas can penetrate the package through the fibrous nonwoven sheet to sterilize the enclosed interior of the package. Suitable fibrous nonwoven sheets also provide a barrier to contaminants, preventing the sterile packaged items from becoming contaminated before the package is opened.

[0006] It is not uncommon for sterile packages to be opened in a sterile environment, and one desirable feature of a fibrous nonwoven sheet is that it be peelable from the package when the sheet is removed without excessive tearing of the surface of the nonwoven sheet. The rupture of the surface of the nonwoven sheet during peeling, which is fiber tearing, is believed by some to potentially contaminate the sterile environment in which the package is opened. Summary of the Invention [Problem to be solved by the invention]

[0007] Since most sterile packages are used in health-related settings such as operating rooms, any improvement that helps prevent or reduce any possible contamination is desirable, and in packaging, any improvement in release performance, especially of fibrous nonwoven structures, is highly desirable. [Means for solving the problem]

[0008] The present invention relates to a package for providing a closed interior environment that can be sterilized comprising a gas permeable fibrous nonwoven sheet structure, a polymeric tie layer and a packaging substrate, wherein the nonwoven sheet structure has a first surface and a second surface, the closed interior environment being formed by sealing an area of ​​contact between the first surface of the nonwoven sheet structure and a packaging structure, the sealed area of ​​contact being formed by the polymeric tie layer, and the first surface of the nonwoven sheet structure being prebonded with an embossed imprint pattern at least within the sealed area of ​​contact.

[0009] The present invention relates to a fibrous nonwoven sheet structure suitable for use in sterile packaging, the sheet structure being gas permeable and having a first surface and a second surface, the first surface being bonded with an embossed imprint pattern and the second surface being capable of accepting printing, the sheet structure having a particle barrier penetration of less than 10%, a Gurley Hill porosity of 40 seconds or less and a porosity of 3500 g / m 2 The present invention also relates to a fibrous nonwoven sheet structure having a water vapor transmission rate of at least 100 / day. [Brief description of the drawings]

[0010] [Figure 1] 1 is an illustration of some embossed patterns. [Diagram 2] 1 is an illustration of some embossed patterns. [Diagram 3] 1 is an illustration of several packaging substrates showing the sealing area. [Figure 4] 1 is an illustration of several packaging substrates showing the sealing area. [Diagram 5] 1 is an illustration of four sample locations for package seal strength determination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention relates to a package for providing a closed internal environment that can be sterilized, and to a gas permeable fibrous nonwoven sheet structure useful in such a structure, the gas permeable fibrous nonwoven sheet structure having at least one surface prebonded with an embossed imprint pattern and having a particle barrier permeation of less than 10%, a Gurley Hill porosity of 40 seconds or less, and a gas permeability of 3500 g / m 2 and a gas permeable fibrous nonwoven sheet structure having a water vapor transmission rate of 100 / day or more.

[0012] It has been unexpectedly discovered that nonwoven sheet structures having a bonding surface with an embossed imprint pattern can be used in sealed packages having an internal environment that can be sterilized. It is surprising that (1) the embossed nonwoven surface can provide a good seal to the package structure, and also (2) the resulting package has an excellent level of peel performance when the package is opened, which is often better than a smooth surface bonding sheet.

[0013] It is desirable for any package that is used and opened in a sterile environment to have a "clean peel" or provide a "sterile peel / presentation," a term used in the medical industry to mean the requirement that the package can be opened and the contents presented to a sterile environment without risk of contamination. As used herein, this superior opening performance is determined by the use of a "fiber tear" criterion. Surprisingly, the use of a nonwoven sheet structure having at least one surface in contact with a polymeric tie layer and prebonded with an embossed imprint pattern can provide a package that has a clean peel and very low or virtually no fiber tear.

[0014] Even more remarkable is that this superior level of release performance is achieved without any additional coating layers on the fibrous nonwoven sheet structure. Although the use of nonwoven coatings may provide improved release, the mere use of such coatings may generate other loose particles that pose a risk to the sterile presentation.

[0015] A package for providing a closed internal environment that can be sterilized includes a gas permeable fibrous nonwoven sheet structure, a polymeric tie layer, and a packaging substrate.

[0016] The packaging substrate can be any material that forms a flexible or semi-rigid package, such as a pouch, bag, sheath or blister pack. The package that includes the packaging substrate generally serves to protect the packaged item, and in the case of sterile packaging, promotes keeping the packaged item in an uncontaminated state until it can be used. In one practical application, the packaged item is placed in the packaging substrate, and then sealed using a polymer tie layer and a gas-permeable fibrous nonwoven sheet structure to form a closed environment. Then, if necessary, the package with the enclosed item can be sterilized using a suitable sterilizing gas. In some embodiments, the packaging substrate includes polyamide (particularly nylon), polypropylene, polyester (particularly polyethylene terephthalate), and any combination thereof.

[0017] The package includes a polymeric tie layer to seal the contact area between the nonwoven sheet structure and the package structure. The polymeric tie layer is preferably any flexible or semi-rigid film that is compatible with both the packaging substrate and the nonwoven sheet structure to adequately seal the nonwoven sheet structure to the packaging substrate. By compatible, it is meant that the polymeric tie layer does not adversely react with either the nonwoven sheet or the packaging substrate and has an adequate shelf life to keep the package sealed until its intended use. In some preferred embodiments, the polymeric tie layer is integral with the packaging substrate. As shown in Figures 3 and 4, sealing regions 15 and 17 illustrate one embodiment of the area where the polymeric tie layer forms a sealed contact area where the packaging substrate and the fibrous nonwoven sheet structure come into contact.

[0018] The polymeric tie layer is preferably in the form of a film. The composition of the polymeric tie layer may include, for example, compositions including polyethylene, including low density polyethylene, ethylene vinyl acetate, and any combination thereof.

[0019] In some preferred embodiments, the polymer tie layer and the packaging substrate are integral. In some embodiments, they are combined in the same film. In this case, as used herein, the packaging substrate is defined as a "structural material" that is integrally combined with a polymer useful as a polymer tie layer in the film. For example, some useful structural materials include polyamide (especially nylon), polypropylene, polyester (especially polyethylene terephthalate), and any combination thereof. Particularly desirable structural material / polymer tie layer combinations that can be used when the packaging substrate and the polymer tie layer are integral include polyamide / polyethylene, polyester / polyethylene, polypropylene / polyethylene, polypropylene / ethylene vinyl acetate, polyamide-polypropylene / polyethylene, etc.

[0020] The fibrous nonwoven sheet structure is gas permeable, meaning that sterilizing gas such as ethylene oxide and / or steam can pass through the sheet without the use of excessive pressure. In particular, the fibrous nonwoven sheet structure has a Gurley porosity (also known as Gurley-Hill porosity) of 40 seconds or less. This porosity is a measure of how long it takes a volume of gas to pass through an area of ​​a material where a certain pressure gradient exists, so a lower number means that the material is more gas permeable and a higher number means that the material is less permeable. In some embodiments, the fibrous nonwoven sheet structure has a Gurley porosity of 10 seconds or less. In some embodiments, the fibrous nonwoven sheet structure has a Gurley porosity of 5 seconds or less, and in some most preferred embodiments, the fibrous nonwoven sheet structure has a Gurley porosity of 3 seconds or less.

[0021] Another measure of permeability is the measurement of water vapor transport, the higher the value the more permeable. This is especially important when steam is used as part of the sterilization process. The fibrous nonwoven sheet structure should have a density of at least 3500 g / m 2 / day or more. In some preferred embodiments, the fibrous nonwoven sheet structure has a water vapor transmission rate of at least 7500 g / m 2 / day or more. In some embodiments, the fibrous nonwoven sheet structure has a moisture vapor transmission rate of at least 9000 g / m 2 / day or greater. Preferably, the fibrous nonwoven sheet structure is uncoated, allowing for a more permeable sheet structure. The use of coatings for improved adhesion tends to close the surface of the nonwoven sheet structure, reducing the rate at which sterilizing gas can pass through the structure.

[0022] The fibrous nonwoven sheet structure has a first surface and a second surface, the first surface being bonded with an embossed imprint pattern. As used herein, the phrase "bonded with an embossed imprint pattern" means that the surface has at least two properties, the first being that the fibrous material on the surface is "bonded" and the fibrous material is substantially consolidated and stabilized by heat and pressure applied to the sheet from a heating source such as a roll, and additionally, the surface has an embossed imprint pattern that leaves a visual texture on the surface. As used herein, the use of the term "prebonded" means that the fibrous nonwoven sheet structure is embossed before being incorporated into any package.

[0023] In one embodiment, the embossed imprint pattern in the sheet is provided by calendering the nonwoven sheet at a nip between a heated metal roll and an elastomeric backup roll, which is provided with a pattern of raised areas or bosses extending radially outward from the surface of the roll. In some preferred embodiments, the raised areas or bosses extend 0.008 to 0.020 inches (0.20 to 0.50 mm) from the remaining surface of the roll. In some other embodiments, the raised areas or bosses may have a width of 0.005 to 0.025 inches (0.12 to 0.64 mm). In some preferred embodiments, the width of the raised areas or bosses may be 0.005 to 0.015 inches (0.12 to 0.38 mm).

[0024] When a fibrous nonwoven sheet is pressed in the nip between a heated metal roll having raised areas or bosses and an elastomeric backup roll, the nonwoven sheet is left with an embossed impression pattern having a depth essentially equal to the dimensions of the bosses. Figures 1 and 2 provide illustrations of two potentially useful and desirable embossed impression patterns, Figure 1 being referred to as a linen pattern and Figure 2 being referred to as a dogbone pattern.

[0025] One preferred method of embossing a nonwoven sheet is to thermally bond the sheet on a modified machine similar to that described in FIG. 2 of U.S. Patent No. 5,972,147 to Janis. In the preheat section of the modified machine, each of the two sides of the nonwoven sheet being bonded is placed in contact with a number of preheat rolls. In some preferred embodiments for embossing nonwoven sheets described herein, the Janis machine is modified so that there are four heated rolls in this section that operate at a temperature sufficient to essentially provide sufficient surface bonding of the sheet. The temperature depends on the melting point of the material being bonded. After the preheat rolls, the sheet passes through preferably only one of a number of embossing stations that are shown to apply an embossing pattern to preferably only one surface of the sheet. On each embossing station there is an embossing roll that can be pressed onto a backup roll to form a nip. The pressure between the embossing roll and the backup roll is expressed in pounds per linear inch (pli). The backup roll is typically covered with an elastomeric covering and is cooled internally with a recirculating cooling medium. The nonwoven sheet is then transferred to multiple cooling rolls where the temperature of the sheet material is reduced and then wound up into a roll. The use of multiple preheat rolls operating at high temperatures not only facilitates bonding the first surface of the nonwoven sheet to be embossed, but also provides an opposing second surface that is also bonded. This second surface is preferably capable of accepting printing. In addition, it is preferred that the second surface have a smooth surface without any embossing for best printing performance. Many packages require very unique bar codes and other subtle and small indicia, which require a very uniform and flat surface without the texture provided by embossing.

[0026] Alternatively, the sheet can be bonded with a first surface, wound up on a roll, and then subsequently rewound and embossed on one side to provide a first surface bonded with an embossed imprint pattern. Other embossing processes are also possible as long as they provide a fibrous nonwoven sheet having at least a first surface bonded with an embossed imprint pattern. Preferably, the process provides a second surface that can accept printing. Preferably, the second surface is uniform and does not have any embossed pattern.

[0027] In some embodiments, the fibrous nonwoven sheet structure has a good barrier against contaminants and has adequate resistance to withstand general handling without damage or contamination to the packaged contents.Thus, the fibrous nonwoven sheet structure with embossed imprint pattern preferably has a particle barrier penetration of less than 10% as determined by a TSI 8130 device.This particle barrier test is believed to be useful in determining the degree of barrier that the sheet provides against contaminants, which may include those that may be bacteria in nature.Furthermore, the fibrous nonwoven sheet structure with embossed imprint pattern preferably has a Mullen burst strength of more than 500 kPa and a measured Elmendorf tear performance of more than 2 N / m.

[0028] Fibrous nonwoven sheet structures include nonwoven fabrics that can provide a stabilizing surface with an embossed imprint pattern for use in contact with a polymeric tie layer on a package. Such nonwoven sheet structures can include flash spun nonwoven sheet structures, spunbond nonwoven sheets, meltblown sheets, electroblown sheets, and any combination thereof. Fibrous means that the material in the nonwoven sheet has some fibrous nature. This fibrous nature can be provided by staple fibers, continuous or semi-continuous fibers, and / or plexifilament fibrous structures, and the like. The fibrous material can include a single material, or multiple materials, either as a combination of different fibers, or as a combination of similar fibers each composed of different materials. The term "nonwoven" means that the planar sheet structure includes at least one web of randomly distributed fibrous material relative to a woven or knitted fabric made of interwoven yarns or loops of interlocked yarns. In some preferred embodiments, the fibrous material in the nonwoven sheet is a synthetic polymer, and in some embodiments, the synthetic polymer is a thermoplastic polymer. In some preferred embodiments, the fibrous materials in the nonwoven sheet structure are free of added binders, i.e., the fibrous materials are bonded in the sheet by fusion of fiber intersections in the sheet structure without additional binder compounds being added to the sheet.

[0029] In some embodiments, the fibrous nonwoven sheet structure has a basis weight of less than 55 grams per square meter. In some more preferred embodiments, the fibrous nonwoven sheet structure has a basis weight of less than 50 grams per square meter, and in some most preferred embodiments, the fibrous nonwoven sheet structure has a basis weight of less than 45 grams per square meter.

[0030] The preferred fibrous material in the fibrous nonwoven sheet structure is plexifilamentary. The terms plexifilamentary and plexifilamentary as used herein refer to a three-dimensional integral network of a plurality of thin, ribbon-like film-fibrils that are random in length and have an average fibril thickness of less than about 4 micrometers and a median width of less than about 25 micrometers. In the plexifilamentary structure, the film-fibrils are generally aligned coextensively with the longitudinal axis of the structure, and intermittently merge and separate at irregular intervals at various locations throughout the length, width and thickness of the structure to form a continuous three-dimensional network. Such structures are described in more detail in U.S. Pat. Nos. 3,081,519 and 3,227,794.

[0031] A preferred method of making fibrous nonwoven sheet structures having plexifilamentary fibrous materials is by flash spinning. The resulting fibrous nonwoven sheet structure containing plexifilamentary film-fibril elements is also known as a flash spun plexifilamentary sheet.

[0032] Thus, preferred fibrous nonwoven sheets suitable for further bonding and embossing can be made using common flash spinning techniques as described in U.S. Patent No. 3,227,794 to Anderson and U.S. Patent No. 3,860,369 to Brethauer et al. Particularly preferred fibrous nonwoven sheets suitable for further bonding and embossing can be made using a spinning solution comprising high density polyethylene and a hydrocarbon spin agent as in, for example, U.S. Patent Nos. 6,010,970, 7,338,916, 8,048,513 and 6,034,008. Preferably, the fibrous nonwoven sheets suitable for further bonding have improved permeability and barrier strength properties by flash spinning the sheets from a hydrocarbon-based spinning solution composed of 12% to 20% by weight polyethylene and maintained at a temperature above 180°C before flashing, in some embodiments the temperature being 185 to 195°C before flashing.

[0033] The fibrous material in the nonwoven sheet is preferably a polyolefin. Polyolefins may include polyethylene, polypropylene, polymethylpentene, polybutylene, and combinations thereof. Preferably, the polyolefin is polyethylene. Polyethylene includes homopolymers of ethylene as well as copolymers in which at least 85% of the repeat units are derived from ethylene. Preferred polyethylenes have an upper melting range of about 130.0-137.0°C, a viscosity of 0.94-0.98 g / cm. 3 and a melt index (as defined in ASTM D-1238-57T, condition E) of 0.1 to 100, preferably 0.1 to 4. Polypropylene includes homopolymers of propylene as well as copolymers in which at least 85% of the repeat units come from propylene units.

[0034] A package including a gas permeable fibrous nonwoven sheet structure, a polymeric tie layer and a packaging substrate provides a closed interior environment that can be sterilized by sealing the contact area between the first surface of the nonwoven sheet, which is prebonded with an embossed imprint pattern, and the packaging structure with the polymeric tie layer.

[0035] In some embodiments, the package can be a type of pouch made from a film having a cavity for the material to be packaged, and a fibrous nonwoven sheet seals the package. In this embodiment, the polymeric tie layer is preferably integral with the film of the pouch, and the tie layer is essentially the film exposed on the interior of the pouch so as to contact the fibrous nonwoven sheet.

[0036] Alternatively, in some embodiments, the package may be a type of blister package, where the package substrate has a thermoformed blister cavity for the material to be packaged, and the fibrous nonwoven sheet structure provides a lidding for the package. Again, in a preferred embodiment, the polymeric tie layer is integral with and is the inner surface of the thermoformed cavity, in contact with the fibrous nonwoven sheet to seal the cavity along with the lip of the package.

[0037] Plan views of two packaging substrates with cavities 16 and 18 are shown in FIG. 3 and FIG. 4, respectively, with the packaging substrates having sealing areas 15 and 17 surrounding the cavities, respectively. When the cavities are sealed, the fibrous nonwoven sheet structure covers both the sealing area and the cavities. A polymer tie layer is placed in the sealing area and positioned between the packaging substrate containing the cavities and the fibrous nonwoven sheet material. The polymer tie layer can be integral with the packaging substrate, which is preferred. In some embodiments, the packages are manufactured by forming the desired packaging substrate with a polymer tie layer, filling the cavities with the material to be packaged, and then applying the nonwoven sheet structure, which is pre-attached with an embossed imprint pattern that is in contact with the polymer tie layer, and then sealed. In some embodiments, the nonwoven sheet structure can be a lidding component for a blister pack. The package is then sealed by either heat, pressure, or a combination of both.

[0038] In some embodiments, the components are heat sealed, typically using a heated platen. While the cavity containing the packaged item is completely sealed, if desired, some other areas on the package do not need to be completely sealed to provide a starting point for peeling the fibrous nonwoven sheet structure prior to removing the product. If the fibrous nonwoven sheet structure is not preprinted before sealing, the nonwoven sheet structure can be printed just before or just after heat sealing.

[0039] While the preferred packaging embodiment is a pouch or blister type package, it is understood that any flexible or semi-rigid package, including packages such as those in the form of a sachet, bag or sheath, may utilize the fibrous nonwoven sheet structure prebonded with an embossed imprint pattern as a gas permeable feature.

[0040] The formed package has a closed interior environment for the packaged item formed by sealing a contact area between a first surface of the nonwoven sheet structure and a packaging substrate, the sealed contact area being a polymeric tie layer, and the first surface of the nonwoven sheet structure being prebonded with an embossed imprint pattern at least in the sealed contact area. In some embodiments, the formed package has a closed interior environment for the packaged item formed by sealing a contact area between a first surface of the nonwoven sheet structure and a packaging substrate, the sealed contact area being a polymeric tie layer, and the first surface of the nonwoven sheet structure being prebonded with an embossed imprint pattern at least in the sealed contact area.

[0041] In some embodiments, the formed package is a heat sealed peelable package. As defined herein, the phrase "peelable package" means that the sheet structure is sealed to the package by a "peelable seal". As defined herein, the phrase "peelable seal" means that the sheet structure sealed to the package has an average peak load seal strength of at least 0.5 bonds per inch to a maximum of 4 pounds per inch or less. This means that the sheet structure can be removed from the sealed package by hand by exerting a seal of at least 0.5 pounds per inch and a seal of at most 4 pounds per inch. In some preferred embodiments, the maximum average peak load seal strength is 3 pounds per inch or less. Furthermore, the fibrous nonwoven sheet structure allows the surface-attached embossed imprint pattern to be able to make a "peelable seal" with the package since it has at least one surface attached with an embossed imprint pattern.

[0042] One measure of seal integrity is characterized by the dye permeation test as described in ASTM F1929-12. Surprisingly, it has been found that packages made of nonwoven sheet structures prebonded with an embossed imprint pattern and attached to a polymeric tie layer by the embossed surface at the seal area do not negatively affect the dye permeation test at all.

[0043] The resulting package has excellent sealing and peeling properties. Surprisingly, the use of a fibrous nonwoven sheet structure having at least one surface in contact with a polymer tie layer and prebonded with an embossed imprint pattern can provide a package with clean peel and very low or virtually no fiber tear. Surprisingly, when the surface of the nonwoven sheet with the embossed pattern is sealed to a film, the peeling properties are improved.

[0044] The improved peeling properties are indicated by both a reduction in the percentage of packages that show fiber tearing and / or a reduction in the severity of fiber tearing.Specifically, it has been found that fibrous nonwoven sheet structures having at least one surface with an embossed imprint pattern have a significant reduction in packages that do not provide clean peeling when compared to non-embossed materials.In particular, it has been found that the use of embossed sheet structures can provide at least a 25 percent reduction, preferably at least a 30 percent reduction, or even a higher reduction in packages that have visible fiber tearing when compared to non-embossed structures.

[0045] Additionally, seal strength, as measured by both average mean load and average peak load, has been found to be improved over the use of a non-embossed fibrous nonwoven sheet structure, in other words, both the strength of the seal and the quality of the peel are improved by the use of an embossed surface on the side of the fibrous nonwoven sheet structure in contact with the polymeric tie layer.

[0046] Test Method Basis Weight. Basis Weight is measured in accordance with ASTM D3776(2009).

[0047] Gurley Hill porosity (or simply "Gurley porosity"; terms used interchangeably herein) is a measure of the permeability of a sheet material to gaseous materials. In particular, it is a measure of how long it takes for a volume of gas to pass through an area of ​​the material in the presence of a particular pressure gradient. Gurley-Hill porosity is measured in accordance with TAPPI T-460 OM-88 using a Lorentzen & Wettre Model SE 166 or 516 from Lorentzen & Wettre, Kista, Sweden. This test measures the time required for 100 cubic centimeters of air to be forced through a 28.7 mm diameter sample (having an area of ​​1 square inch) under a pressure of approximately 1.21 kPa (4.9 inches) of water. Results are often expressed in seconds, referred to as Gurley seconds. Reported values ​​represent the average of at least 12 individual measurements.

[0048] Water Vapor Transmission Rate. Water vapor transmission rate (MVTR) is measured according to EN ISO 12572, Hygrothermal performance of building materials and products, Climate C, 2001. Measurements are performed using a multi-layer method with 100% relative humidity in the cup and an air flow over the sample of 2.5 m / s and using a measurement interval of 30 minutes. The resulting MVTR is determined based on the weight loss of water in the sample. The reported value represents the average of at least one measurement. Measurements are performed on a Gintronic Gravitest 6400 with an ES 420A balance from MRS Seitter, Lenning-Bruck, Germany.

[0049] Particle Transmission. Particle transmission is measured with a TSI 8130 instrument from TSI Incorporated, Shoreview, MN, United States. The TSI 8130 is the instrument used for measurements according to NIOSH procedure numbers RCT-APR-STP-57, 58, 59. For the analysis, the TSI 8130 instrument is used with sodium chloride particle generation at a flow rate of 2.3 liters per minute. To achieve a flow rate of 2.3 liters per minute, the control valve is closed and the air flow is from air passing only through the downstream photometer. The sodium chloride particle distribution has a count median diameter of 0.075 μm, a mass mean diameter of 0.3 μm and a geometric standard deviation of 1.8. Measurements are made with a rise time of 25 seconds and a measurement time of 4 seconds. Transmission is measured based on the difference in light intensity due to the upstream and downstream photometers. The reported transmission is the average of at least six measurements. Particle transmission is instead calculated using the following formula: LRV-TSI 8130=-log10(transmission[%] / 100) The logarithmic reduction can be expressed as a logarithmic reduction based on

[0050] Elmendorf Tear. Elmendorf Tear is measured according to ISO 1974:1990; Paper - Determination of tearing resistance (Elmendorf method). Elmendorf is measured with a 09 ED tear tester from Lorentzen & Wettre, Kista, Sweden. Elmendorf Tear is measured in both machine direction (MD) and cross direction (XD).

[0051] Mullen burst strength. Mullen burst strength is measured according to ISO 2758:2001. Paper - Determination of bursting strength. Mullen burst is measured using a Lorenzen & Wettre Model 519L from Lorentzen & Wettre, Kista, Sweden, which is integrated into an Autoline 400 from Lorentzen & Wettre, Kista, Sweden.

[0052] Seal Strength. Seal strength is measured according to ASTM F88 / F88M Appendix C in the "free tail" mode. Four strips per test package 25 are cut at the specified locations with a width of 1 inch to test the seals 20, as shown in FIG. 5. The ends of the strips are clean cut and perpendicular to the direction of the seal. The hardest part of the seal was placed on the upper clamp. The produced nonwoven sheet is the hardest part of the seal and therefore placed on the upper clamp. The seals were tested at a grip separation speed of 300 mm / min. The number of measurements per test item is at least equal to 24. Seal strength is reported both as the average of the mean load seal strength and the average of the peak load seal strength in pounds force per inch, lbf / in.

[0053] Dye Penetration. Dye penetration is performed in accordance with ASTM F1929-12 "Standard Test method for Detecting Seal Leaks in Porous Mecial packaging by Dye Penetration". ASTM F1929-12 specifies a procedure for detecting and locating leaks equal to or greater than a groove formed by a 50 μm (0.002 in) wire in a package edge seal formed between a transparent material and a porous sheet material. A dye penetrant solution is applied topically to the sealed edge being tested for leakage. After a specified period of contact of 5 seconds with the dye penetrant solution, the package is visually inspected for dye penetration. If no grooves are visually visible, the package is deemed to have "passed" the dye penetration test.

[0054] Printing. The nonwoven sheet is printed with a linear barcode or a 2D Data Matrix. Testing of linear barcodes is performed according to ISO 15416 and testing of 2D Data Matrix is ​​performed as described in ISO 15415.

[0055] Fiber tear. Fiber tear is performed by visual inspection of the opened packages. The packages are opened by hand in the following way: the nonwoven sheet is held in one hand and the film in the other hand. The time to open one package is about 1 second. The package is not opened until it reaches the bottom end seal. In other words, the package is not opened completely except for the top seal and the two seals on the side. After each package is opened, the surface of the nonwoven sheet sealed against the film is inspected. The surface should be uniform and continuous without the presence of peeling and tearing of the nonwoven sheet. The package has fiber tear if there is peeling or tearing of the nonwoven sheet. The above procedure is performed for at least 50 packages. The percentage of packages showing fiber tear is determined from the number of packages showing fiber tear divided by the total number of packages opened. Alternatively, fiber tear can be performed according to EN 868-5 (2009), Appendix E. However, this standard does not count some smaller length visual fibers. As shown in the examples and defined herein, a "package exhibiting fiber tear" is one that has attached fibers of any length that are visible to the unassisted eye after opening. EXAMPLES

[0056] Example 1 and Example 2 Unfinished fibrous nonwoven sheets for further bonding and embossing were made from a spinning solution containing high density polyethylene and n-pentane hydrocarbon spin agent using a general flash spinning process as described in Examples 9-15 of U.S. Patent No. 6,034,008 to Lim et al., except that the polymer concentration in the spinning solution was 17 wt % and the spinning temperature was 195° C. The polyethylene had a melt flow index of 2.16 kg / 190° C. of about 0.75 g / 10 min (as measured by ASTM D1238-13). Nonwoven sheets of two different basis weights were made.

[0057] The unfinished fibrous nonwoven sheet was then bonded in an embossed imprint pattern by modification to the process described in U.S. Patent No. 5,972,147 to Janis, specifically by adapting the apparatus shown in FIG. 2 of that patent. In the process shown in the figure, the sheet was preheated by a single set of two preheat rolls, which alternately wrapped around the sheet, followed by bonding of the sheet at the nip of two sets of two calender rolls, where the first set of rolls bonded one side of the sheet and the second set of rolls bonded the other side of the sheet, followed by cooling of the sheet by a single set of two chill rolls. In particular, the Janis process was modified to use an additional set of preheat rolls, such that the sheet was alternately wrapped around four preheat rolls (versus two) without any nips between the rolls. Additionally, only the second set of calender rolls nips the sheet, and operates at a nip pressure of about 200 pounds per lineal inch. The first set of calender rolls was left open and did not nip the sheet. This was followed by cooling of the sheet by two sets of two chill rolls (versus two single sets).

[0058] The particular equipment arrangement involved the bottom of the sheet wrapping around the first preheat roll (PH1), the top of the sheet wrapping around the second preheat roll (PH2), followed by the bottom of the sheet wrapping around the third preheat roll (PH3), and then the top of the sheet wrapping around the second preheat roll (PH4). The first set of calender rolls did not nip the sheet, so the top surface of the sheet was not embossed. The second set of calender rolls bonded the bottom surface of the sheet and embossed the linen imprint pattern as shown in FIG. 1 in the surface of the sheet.

[0059] The sheet was then transferred to a cooling section and then wound up into a roll. The preheat roll and embossing machine temperatures are shown in Table 1 and the resulting sheet properties are summarized in Table 2.

[0060] [Table 1]

[0061] [Table 2]

[0062] Comparative Example A Unfinished fibrous nonwoven sheets for further bonding and embossing were made from a spinning solution containing high density polyethylene and n-pentane hydrocarbon spin agent using a general flash spinning process as described in Examples 9-15 of U.S. Patent No. 6,034,008 to Lim et al., except that the polymer concentration in the spinning solution was 17 wt % and the spinning temperature was 185° C. The polyethylene had a melt flow index of 2.16 kg / 190° C. (as measured by ASTM D1238-13) of about 0.7 g / 10 min.

[0063] The unfinished fibrous nonwoven sheet was then bonded by a process generally as described in U.S. Patent No. 3,532,589 to David using a steam pressure of 66.7 psia. This is the process described in U.S. Patent No. 6,034,008 to Lim et al. to produce a "hard-structure" nonwoven sheet. In this process, the nonwoven sheet is then passed over a heated drum, followed by a cooled drum, then another heated drum and a cooled drum to thermally bond both sides of the material. The heated drum is held at a temperature that results in partial melting of the nonwoven sheet to induce sheet bonding. The resulting sheet properties are summarized in Table 3.

[0064] [Table 3]

[0065] Example 3 Each of them is 44 grams per meter 2The resulting nonwoven sheets from Example 1 and Comparative Example A, having a basis weight of 100 g / g, are then used to make medical packages using a Multivac R535 machine. The Multivac R535 machine makes four packages on one substrate, each package having a length of 200 mm lengthwise and approximately 95 mm widthwise and a sealing width of approximately 7.5 mm, as shown as dimension 5 in FIG. 3. The nonwoven sheets were attached to the package substrates at sealing contact areas using two different tie film materials. Film 1 was Multifol GA Tyvek®, a 100 μm polyamide / polyethylene peelable film from Suedpack Verpackungen GmbH&Co.KG, Ochsenhausen, Germany. Film 2 was Wipak® ML E 135 TF PEEL, a polyethylene / polyamide / polyethylene film from Wipak, Nastola, Finland.

[0066] In all cases, the nonwoven surface from the bonded and linen pattern embossed nonwoven sheet of Example 1 was sealed to the film. All packages were made with a sealing pressure of 6.5 bar and a dwell time of 1.2 seconds. The sealing temperature was set at at least two levels for each film - resulting in different seal strengths. The packages were then opened by peeling the nonwoven sheet from the tie film.

[0067] The sealing temperatures and resulting seal strength values ​​are shown in Table 4. With increasing sealing temperature, the average peak seal strength and average intermediate seal strength increased for the individual films. Also, at higher seal strengths, the percentage of packages exhibiting fiber tear increases. However, in all cases, the nonwoven sheets with the embossed pattern had both improved fiber tear (peel) and seal performance, with the percentage reduction in fiber tear ranging from 32% to 73%.

[0068] [Table 4]

[0069] Example 4 and Comparative Example B 47g / m with the same embossed linen pattern 2 Example 2 was repeated using a nonwoven sheet having a basis weight of 1.0 g / m2, but the unfinished sheet was bonded using the embossing conditions shown in Table 5. The resulting bonded nonwoven sheet had a Gurley porosity of 3.6 seconds.

[0070] For Comparative Example B, the process was repeated with sheets of the same basis weight and temperature conditions as shown in Table 5, but without embossing the bottom of the sheet. (The sheet was not nipped with the calender rolls.) The resulting nonwoven sheet was bonded without any embossing and had a Gurley porosity of 2 seconds.

[0071] [Table 5]

[0072] The resulting nonwoven sheet with bonded and linen pattern embossed surface and the bonded nonwoven sheet without any embossing were then used to make medical packages using an Autovak M320 machine, Hongkong, China. The Autovak machine simultaneously produced two packages with a length of about 190 mm in the longitudinal direction and 127 mm in the transverse direction and a sealing width of 10 mm as shown by the dimension 10 in FIG. 4. The nonwoven sheet was attached to the package substrate at sealing the contact area using a 135 μm thick polyamide / polyethylene peelable tie film with code UGBLGV340C from Xiangfu(zhongshan)Film Packaging Co.,LTD,180,Zhongshan 5th Rd,Guandong,China. The film is preheated in the forming zone. The temperature of the forming zone is 105° C. and the residence time is set equal to 1.0 second. The sealing temperature for all packages is set equal to 120° C. The residence time is adapted to change the resulting seal strength of the package. The seal times and seal strengths are shown in Table 6. The packages were then opened by peeling the nonwoven sheet from the tie film. As shown in Table 6, the packages using the nonwoven sheet that was only bonded and not embossed had higher seal strength properties but showed overall unacceptable fiber tear performance, while the packages using the embossed nonwoven sheet had acceptable seal strength properties and excellent fiber tear (peel) performance.

[0073] [Table 6]

[0074] Example 5, Example 6 and Example 7 These examples illustrate that embossing can be applied to the nonwoven sheet as a separate step after nonwoven sheet bonding. Comparative Example B, in which the nonwoven sheet is bonded but not embossed, was repeated using two different nonwoven sheet basis weights. The bonded sheet was then wound up into a roll. The roll of bonded nonwoven sheet was then subsequently unwound and embossed on one surface by nipping the sheet with a pair of heated calender rolls, this time providing one surface of the sheet with an embossed dogbone pattern as shown in FIG. 2 rather than a linen pattern. The conditions for bonding and subsequent embossing are shown in Table 7. Packages were made with the same tie film with the embossed surface in contact with the tie film as in Example 4. The results are shown in Table 8.

[0075] [Table 7] (* - not measured)

[0076] [Table 8]

[0077] The package was then opened by peeling the nonwoven sheet from the tie film. As shown in Table 8, the package using the embossed nonwoven sheet had excellent peel performance.

[0078] Example 8 The nonwoven sheet structures with embossed imprint patterns used in Examples 1-7 were tested for barrier and mechanical properties. All of these inventive sheet structures had an Elmendorf tear of greater than 2.0 N and a Mullen burst strength of greater than 500 kPa. All of the inventive sheet structures had a particle barrier penetration of less than 10% using a TSI 8130 instrument operated at a flow rate of 2.3 L / min. The non-embossed side of each of the nonwoven structures allows printing in the form of line bar codes and 2D data matrices with good visual results.

Claims

1. 1. A package for providing an enclosed internal environment that can be sterilized, comprising a gas permeable fibrous nonwoven sheet structure, a polymeric tie layer, and a packaging substrate, the nonwoven sheet structure having a first surface and a second surface; the enclosed interior environment is formed by sealing a contact area between the first surface of the nonwoven sheet structure and the package structure, the sealed contact area being formed by the polymer tie layer; The first surface of the nonwoven sheet structure is prebonded in an imprint pattern at least in the sealed contact area.

2. The package of claim 1 , wherein the polymer tie layer is integral with the package substrate.

3. The package of claim 1 , wherein the polymer tie layer and the package substrate are combined in a film.

4. The package according to any one of claims 1 to 3, wherein the fibrous nonwoven sheet structure is plexifilamentary.

5. The package of claim 4 , wherein the fibrous nonwoven sheet structure comprises polyethylene plexifilaments.

6. A fibrous nonwoven sheet structure suitable for use in sterile packaging, the structure being gas permeable and having a first surface and a second surface, the structure comprising: the first surface being bounded with an embossed imprint pattern and the second surface being capable of accepting printing; The sheet structure has a particle barrier permeability of less than 10%, a Gurley Hill porosity of less than 40 seconds and a surface area of ​​3500 g / m 2 A fibrous nonwoven sheet structure having a water vapor transmission rate of 100 / day or more.

7. 7. The fibrous nonwoven sheet structure of claim 6 having a Gurley Hill porosity of 10 seconds or less.

8. 7500g / m 2 8. The fibrous nonwoven sheet structure of claim 6 or 7, having a water vapor transmission rate of at least 100 / day.

9. 9000g / m 2 10. The fibrous nonwoven sheet structure of claim 8 having a moisture vapor transmission rate of at least 100 / day.

10. The fibrous nonwoven sheet structure of any one of claims 6 to 9 which is plexifilamentary.

11. 11. The fibrous nonwoven sheet structure of claim 10 comprising polyethylene plexifilaments.

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