Flash spin fluid comprising azeotropic and azeotrope-like compositions of trans-1,2-dichloroethylene and 1h,1h,2h- heptafluorocyclopentane or of trans-1,2-dichloroethylene, 1h,1h,2h-heptafluorocyclopentane, and 2h,3h-decafluoropentane

Abstract

The present invention relates (i) to a spin fluid for flash spinning a polyethylene or a polyethylene blend comprising an azeotropic or azeotrope-like composition comprising (a) trans-1,2-dichloroethylene and 1H,1H,2H-heptafluorocyclopentane, or (b) trans-1,2-dichloro-ethylene, 1H,1H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane, and (ii) to a process for the preparation of plexifilamentary fibrils of polyethylene or polyethylene blend using the spin fluid.

Description

[0001] TITLE

[0002] FLASH SPIN FLUID COMPRISING AZEOTROPIC AND AZEOTROPE-LIKE COMPOSITIONS OF TRANS-1 ,2-DICHLOROETHYLENE AND 1 H, 1 H,2H- HEPTAFLUOROCYCLOPENTANE OR OF TRANS-1 ,2-DICHLOROETHYLENE, 1 H,1 H,2H-HEPTAFLUOROCYCLOPENTANE, AND 2H,3H- DECAFLUOROPENTANE

[0003] FIELD OF THE INVENTION

[0004] The present invention relates (i) to a spin fluid for flash spinning a polyethylene or a polyethylene blend comprising an azeotropic or azeotrope-like composition comprising (a) trans-1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (b) trans-1 ,2-dichloro- ethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane and (ii) to a process for the preparation of plexifilamentary fibrils of polyethylene or polyethylene blend using the spin fluid.

[0005] BACKGROUND

[0006] Flash spinning is a process for producing fibrils that involves the following steps: (i) dissolving a polymer in a composition comprising one or more solvents (often called a spin agent), at elevated temperature and pressure to form a homogeneous solution (often called a spin fluid), (ii) reducing the pressure sufficiently below the spin fluid’s cloud point pressure (i.e., the pressure at which the spin fluid transitions from a clear solution to a cloudy, two- phase dispersion), while still maintaining sufficient pressure to prevent the spin fluid from reaching its bubble point pressure (i.e., the pressure at which the spin agent in the spin fluid begins to boil), (iii) releasing the resulting dispersion continuously through one or more orifices into a lower pressure region at or near atmospheric temperature and pressure so that the spin agent flash evaporates as it emerges from the one or more orifices, (iv) collecting the polymer which remains as a stream of fibrils, e.g., plexifilamentary fibrils, and (v) recovering the evaporated spin agent for re-use. Examples of flash spinning processes are disclosed in US 3,227,794.

[0007] In a commercial flash spinning process, the spin agent’s solvent properties and physical properties are critical. In particular, the solvent properties of the spin agent determine whether and under what conditions fibrils are produced in the flash spinning process, and the spin agent’s physical properties impact the process for recovering and re-using the spin agent. The process for recovering spin agents typically involves a step in which the spin agent is condensed from the gas state to the liquid state, and it is preferred that the composition of the spin agent remains essentially constant during this step. This is inherent when spin agents comprise only one solvent but not when they comprise two or more solvents, which are often required to provide the necessary solvent properties for flash spinning the desired polymer. Accordingly, when using a spin agent that comprises two or more solvents, it is advantageous to use a composition that is azeotropic or azeotrope-like which behaves similarly to a spin agent with only one solvent.

[0008] One example of a commonly used solvent for polymers such as polyolefins is 1 ,2- dichloroethylene (DCE). However, DCE is a strong solvent for polyolefins and when mixed with polyethylene to form a spin fluid, the spin fluid fails to produce a cloud point below temperatures of about 225°C. The use of DCE as a single spin agent is therefore not desirable to perform the flash spinning process at reduced temperatures following the description in US 3,227,794. Weaker solvents such as fluorinated compounds, hydrofluorocarbons, or hydrofluoroethers can be mixed with DCE to reduce the solvent strength of the spin agent and increase the spin fluid’s cloud point pressure such that flash spinning can be readily accomplished for a wider range of temperature.

[0009] WO 2016 / 200873 A1 suggests spin agent compositions of 1 ,2-dichloroethylene with 1 H,6H-perfluorohexane, 1 H-perfluorohexane, or 1 H-perfluoroheptane. However, use of such linear C6 or C7 hydrofluorocarbons in combination with DCE results in spin agents that often exhibit undesirably high global warming potential (GWP). In view of the growing concerns regarding climate change and increasing regulatory requirements, it is desirable to find suitable spin agent compositions with a lower GWP. Such spin agent composition should also form a homogeneous liquid phase at ambient temperatures and pressures, rather than a heterogeneous liquid phase where, due to low miscibility of the components of the spin agent composition, a liquid phase separation occurs. Compositions forming heterogeneous liquid phases are usually undesired since processes involving such compositions are more complex and expensive due to the liquid phase separation.

[0010] US 5,672,307 and US 5,977,237 report a flash spinning process using spin agent compositions of 1 ,2-dichloroethylene with cyclic perfluorocarbons, such as perfluoro- 1 ,2- dimethylcyclobutane, and perfluoro-N-methylmorpholine, or with various fluorobutyl- or fluoropropyl-ethers. US 10,329,692 B2 reports a flash spinning process of polyethylene using spin agent compositions of 1 ,2-dichloroethylene with cyclic partially fluorinated hydrocarbons, such as 1 ,1 ,2,2,3,3-hexafluorocyclopentane, and cis-1 ,1 ,2,2,3,3,4,5-octafluorocyclopentane. However, the disclosed compositions complicate the spin agent recovery process since (i) many of the disclosed fluorinated components are not miscible with chlorinated components such as DCE at ambient temperatures and pressures, which results in a heterogeneous liquid phase of the non-DCE component and the DCE after condensation of the spin agent, i.e., to a liquid phase separation of the two components, and / or (ii) the disclosed compositions do not form an azeotropic or azeotrope- 1 ike composition at the specifically disclosed ratios. Where an azeotrope forms between DCE and the non-DCE component, in the spin agent, it is beneficial if this is a positive azeotrope because the boiling point of the azeotrope is then lower than that of either individual component of the spin agent composition. This allows the low- pressure region into which flash spinning takes place (i.e. , the spin-cell) to be maintained at a lower temperature without risking the spin agent condensing inside it. This also reduces the need for spin-cell heating and provides a more comfortable environment for operators working near the spin-cell. On the other hand, a negative azeotrope, which has a higher boiling point than that of either individual component of the spin agent composition, could require spin-cell heating which would lead to increased equipment and operating costs.

[0011] US 7,067,468 B2 reports azeotropic and azeotrope- 1 ike compositions, such as an azeotropic and azeotrope- 1 ike composition of trans- 1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane, for applications as solvents in refrigeration flushing, oxygen system cleaning, foam blowing, and cleaning operations such as cold cleaning, vapor degreasing, and aerosol cleaners. However, US 7,067,468 B2 does not report the use of any composition to dissolve polymers or suggest its use as a spin agent for flash spinning.

[0012] US 7,540,973 B2 reports azeotropic and azeotrope- 1 ike compositions, such as an azeotropic and azeotrope- 1 ike composition of trans-1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane as solvents for cleaning applications. However, US 7,540,973 B2 does not report the use of any composition to dissolve polymers or suggest its use as a spin agent for flash spinning.

[0013] Accordingly, there is a need for, and the present inventors have discovered, azeotropic and azeotrope-like compositions that (i) form a positive homogenous azeotrope with a boiling temperature below 40 °C, (ii) simplify the spin agent recovery and re-use process, and (iii) provide suitable cloud point pressures for flash spinning polyethylene.

[0014] SUMMARY OF THE INVENTION

[0015] In one embodiment, the invention is directed to a spin fluid for flash spinning comprising (a) from about 8 to about 26 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises (1) an azeotropic or azeotrope-like composition comprising trans-1 ,2- dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane. In a further embodiment, the invention is directed to a process for the preparation of plexifilamentary fibrils of polyethylene or polyethylene blend. The process comprises the steps of:

[0016] (i) generating a spin fluid comprising

[0017] (a) about 8 to about 26 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and

[0018] (b) a spin agent, and

[0019] (ii) flash spinning the spin fluid 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 polyethylene, wherein the spin agent comprises (1) an azeotropic or azeotrope-like composition comprising trans-1 ,2-dichloroethylene and 1 H, 1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising trans-1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0020] BRIEF DESCRIPTION OF THE FIGURES

[0021] Fig. 1 shows the cloud point pressure curve of a spin fluid comprising 14 wt% polyethylene and a spin agent of trans-1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane in a 82:18 ratio by weight.

[0022] Fig. 2 shows the cloud point pressure curve of a spin fluid comprising 14 wt% polyethylene and a spin agent of trans-1 ,2-dichloroethylene,1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 80:10:10 ratio by weight.

[0023] Fig. 3 shows the cloud point pressure curve of a spin fluid comprising 14 wt% polyethylene and a spin agent of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:15:10 ratio by weight.

[0024] Fig. 4 shows the cloud point pressure curves of a spin fluid comprising 8 or 18 wt% polyethylene and a spin agent of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:10:15 ratio by weight.

[0025] DETAILED DESCRIPTION

[0026] Definitions and Clarification of Terms

[0027] 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. Density is determined according to the method described in ISO 1183 (Plastics - Methods for determining the density of non-cellular plastics).

[0028] 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.

[0029] 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 (2.16kg), 5000 grams (5kg) or 21 ,600 grams (21.6kg).

[0030] 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.

[0031] 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 of about 123 °C to about 140 °C, a density of 0.94 to 0.98 grams per cubic centimeter (ISO 1183), and a melt flow rate (ISO 1133, 190 °C / 2160 grams) of between 0.05 g / 10min and 30 g / 10min, preferably less than 4 g / 10min, and / or a melt flow rate (ISO 1133, 190 °C / 21 ,600 grams) of between 1 g / 10min and 15 g / 10min.

[0032] The term “polyethylene blend” (PE blend) is intended to embrace, without limitation, polymer blends comprising from about 50 to less than about 100 weight percent, or from about 70 to about 99 weight percent, or from about 70 to about 95 weight percent, or from about 80 to about 95 weight percent of polyethylene, and from about 50 to more than about 0 weight percent, or from about 30 to about 1 weight percent, or from about 30 to about 5 weight percent, or from about 20 to about 5 weight percent, of one or more other polyolefins, such as polypropylene.

[0033] 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.

[0034] 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.

[0035] The term “spin fluid” refers to a solution for spinning in a flash spinning process comprising a polyethylene and a spin agent. The solution may also include one or more additives.

[0036] The term “dew point pressure” refers to the pressure at which, at constant temperature, liquid starts condensing from a vapor, vapor mixture, or vapor-gas mixture.

[0037] The term “bubble point pressure” refers to the pressure at which, at constant temperature, a liquid, liquid mixture, or liquid-solution begins to boil.

[0038] The term “azeotropic composition” refers to a composition comprising two or more fluids wherein the bubble point pressure equals the dew point pressure. An azeotropic composition boils without change of the composition and behaves as a single substance.

[0039] The term “azeotrope- 1 ike composition” refers to a composition comprising two or more fluids which boils without substantial change of the composition and behaves substantially as a single substance. For a composition comprising two fluids, the term “azeotrope-like composition” refers to a composition which exhibits only small differences between the dew point pressure and the bubble point pressure, i.e., the dew point pressure is different by 5% or less from the bubble point pressure (both expressed in absolute pressure). For a composition comprising three fluids, the term “azeotrope-like composition” refers to a composition, where, after 50 weight percent of the composition is removed, such as by evaporation or boiling off, the difference in bubble point pressure between the original composition and the composition remaining after 50 weight percent of the original composition has been removed by evaporation or boil off is less than 5 percent.

[0040] 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. Atmospheric pressure means 101.325 kPa. Essentially atmospheric pressure means 101.325 kPa ± 5 %.

[0041] 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.

[0042] Spin Agents and Spin Fluids for Flash Spinning

[0043] Provided herein are spin agents and spin fluids for flash spinning of polyethylene or polyethylene blend.

[0044] In some embodiments, the spin fluid for flash spinning polyethylene comprises (a) from about 6 to about 24 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane, or (2) an azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane. In other embodiments, the spin fluid comprises (a) from about 6 to about 20 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane, or (2) an azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0045] In other embodiments, the spin fluid comprises (a) from about 8 to about 20 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0046] In other embodiments, the spin fluid comprises (a) from about 8 to about 16 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope- 1 ike composition comprising, consisting essentially of, or consisting of trans- 1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising, consisting essentially of, or consisting of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0047] In other embodiments, the spin fluid comprises (a) from about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially (1) an azeotropic or azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising, consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0048] In some embodiments, the spin fluid comprises from about 76 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 80 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 92 weight percent, based on the total amount of the spin fluid, in other embodiments from about 84 to about 92 weight percent, based on the total amount of the spin fluid, and in other embodiments from about 86 to about 92 weight percent, based on the total amount of the spin fluid.

[0049] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotropic or azeotrope-like composition consisting essentially of or consisting of from about 61 to about 85 weight percent trans- 1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, or from about 71 to about 85 weight percent trans- 1 ,2-dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0050] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotropic composition consisting essentially of or consisting of from about 78 to about 82 weight percent trans-1 ,2-dichloroethylene and from about 22 to about 18 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at temperature of from about 40 °C to about 100 °C and at a boiling pressure of from about 80 kPa to about 459 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 81.5 weight percent trans-1 ,2-dichloroethylene and about 18.5 weight percent 1 H,1 H,2H- heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 40 °C and at a boiling pressure of about 80.3 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 80.0 weight percent trans-1 ,2-dichloroethylene and about 20.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 60 °C and at a boiling pressure of about 155.6 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 79.0 weight percent trans- 1 ,2-dichloroethylene and about 21.0 weight percent 1 H,1 H,2H- heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 80 °C and at a boiling pressure of about 276.7 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 78.0 weight percent trans-1 ,2- dichloroethylene and about 22.0 weight percent 1 H, 1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 100 °C and at a boiling pressure of about 459 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 81.1 weight percent trans- 1 ,2-dichloroethylene and about 18.9 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 46.7 °C and at a boiling pressure of about 101.3 kPa.

[0051] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope- 1 ike composition consisting essentially of or consisting of from about 65 to about 85 weight percent trans- 1 ,2-dichloroethylene, and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H- decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent or about 5 weight percent, and the minimum amount of 2H,3H- decafluoropentane is about 2 weight percent or about 5 weight percent, each based on the total amount of the azeotrope-like composition. In some embodiments, these azeotrope-like compositions boil at a temperature of about 20 °C and at a boiling pressure of about 37.5 kPa to about 44.2 kPa, in other embodiments, these azeotrope- 1 ike compositions boil at a temperature of about 40 °C and at a boiling pressure of about 81 kPa to about 95.5 kPa, and in other embodiments these azeotrope- 1 ike compositions boil at a temperature of about 60 °C and at a boiling pressure of about 157 kPa to about 185 kPa. In some embodiments, these azeotrope-like compositions boil at a boiling pressure of about 101.3 kPa at a temperature of about 41 °C to about 45 °C.

[0052] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope-like composition consisting essentially of or consisting of from about 70 to about 85 weight percent, or about 70 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 30 to about 15 weight percent, or from about 30 to about 18 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent or about 5 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent or about 5 weight percent, each based on the total amount of the azeotrope-like composition.

[0053] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope- 1 ike composition consisting essentially of or consisting of from about 75 to about 82 weight percent trans- 1 ,2-dichloroethylene, and from about 18 to about 25 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H- decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent or about 5 weight percent, and the minimum amount of 2H,3H- decafluoropentane is about 2 weight percent or about 5 weight percent, each based on the total amount of the azeotrope- 1 ike composition.

[0054] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope- 1 ike composition consisting essentially of or consisting of about 80 weight percent trans- 1 ,2-dichloroethylene, about 10 weight percent 1 H,1 H,2H- heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, in other embodiments of about 75 weight percent trans-1 ,2-dichloroethylene, about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, and in other embodiments of about 75 weight percent trans- 1 ,2-dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 15 weight percent 2H,3H- decafluoropentane.

[0055] The spin fluid may include additives, such as antioxidants or acid scavengers in minor amounts, provided that their presence does not interfere with the azeotropic or azeotrope-like nature of the compositions of trans-1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane or of the compositions of trans- 1 ,2-dichloroethylene, and 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane described herein. 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 agent, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin agent.

[0056] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, , based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 61 to about 85 weight percent trans-1 ,2- dichloroethylene and from about 39 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane, or from about 71 to about 85 weight percent trans-1 ,2- dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0057] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 65 to about 85 weight percent, or from about 70 to about 85 weight percent, or from about 70 to about 82 weight percent, or from about 75 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 35 to about 15 weight percent, or from about 30 to about 15 weight percent or from about 30 to about 18 weight percent or from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent, each based on the total amount of the azeotrope-like composition.

[0058] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 65 to about 85 weight percent, or from about 70 to about 85 weight percent, or from about 70 to about 82 weight percent, or from about 75 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 35 to about 15 weight percent, or from about 30 to about 15 weight percent or from about 30 to about 18 weight percent or from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 5 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 5 weight percent, each based on the total amount of the azeotrope-like composition.

[0059] Particularly preferred polyethylenes are 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).

[0060] In some embodiments, the PE blend comprises from about 50 to less than about 100 weight percent, or from about 70 to about 99 weight percent, or from about 70 to about 95 weight percent, or from about 80 to about 95 weight percent of polyethylene, and from about 50 to more than about 0 weight percent, or from about 30 to about 1 weight percent, or from about 30 to about 5 weight percent, or from about 20 to about 5 weight percent, of one or more other polyolefins, such as polypropylene.

[0061] In some embodiments, the spin fluid comprising the azeotropic or azeotrope-like composition as described herein exhibits a cloud point pressure of about 45 to about 300 bar, in other embodiments of about 50 to about 300 bar, and in other embodiments of about 70 to about 300 bar. In some embodiments, the spin fluid comprising the azeotropic or azeotropelike composition as described herein exhibits a cloud point pressure of about 45 to about 250 bar, in other embodiments of about 50 to about 250 bar, and in other embodiments of about 70 to about 250 bar. In some embodiments, the spin fluid comprising the azeotropic or azeotrope- 1 ike composition as described herein exhibits a cloud point pressure of about 45 to about 200 bar, in other embodiments of about 50 to about 200 bar, and in other embodiments of about 70 to about 200 bar. The flash spinning process must take place at an operating pressure below the spin fluid’s cloud point pressure but above the spin fluid’s bubble point pressure. If the cloud point pressure is above about 300 bar, the flash spinning equipment must be built to withstand very high pressure which increases costs and operational constraints.

[0062] When used as a spin agent, the homogeneous azeotropic or azeotrope- 1 ike compositions have the advantage that in the spin agent recovery process, upon condensation of the spin agent, no phase separation occurs. Furthermore, the azeotropic or azeotrope- 1 ike compositions described herein result in spin fluids with a cloud point pressure at or close to the azeotrope. This makes it easier to condense the used spin agent into a liquid with the same or substantially the same composition so that it can be re-used.

[0063] Preparation of Plexifilamentary Fibrils of Polyethylene or Polyethylene Blend

[0064] In some embodiments, there is provided a process for the preparation of plexifilamentary fibrils of polyethylene or polyethylene blend. The process comprises the steps of:

[0065] (i) generating a spin fluid comprising

[0066] (a) about 6 to about 24 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and

[0067] (b) a spin agent, and

[0068] (ii) flash spinning the spin fluid 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 polyethylene or polyethylene blend, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope- 1 ike composition comprising consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane or (2) an azeotrope-like composition comprising consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0069] In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 300 bar, or of about 50 to about 300 bar, or of about 70 to about 300 bar. In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 250 bar, in other embodiments of about 50 to about 250 bar, and in other embodiments of about 70 to about 250 bar. In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 200 bar, in other embodiments of about 50 to about 200 bar, and in other embodiments of about 70 to about 200 bar. The region of lower pressure into which flash spinning occurs is usually at or around atmospheric pressure.

[0070] In some embodiments, the spin fluid comprises (a) from about 8 to about 20 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope-like composition comprising consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane. In other embodiments, the spin fluid comprises (a) from about 8 to about 16 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of (1) an azeotropic or azeotrope- 1 ike composition comprising consisting essentially of, or consisting of trans-1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or (2) an azeotrope-like composition comprising consisting essentially of, or consisting of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane. In other embodiments, the spin fluid comprises (a) from about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially (1) an azeotropic or azeotrope-like composition comprising consisting essentially of, or consisting of trans- 1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane, or (2) an azeotrope-like composition comprising consisting essentially of, or consisting of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0071] In some embodiments, the spin fluid comprises from about 76 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 80 to about 94 weight percent of a spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 92 weight percent, based on the total amount of the spin fluid, in other embodiments from about 84 to about 92 weight percent, based on the total amount of the spin fluid, and in other embodiments from about 86 to about 92 weight percent, based on the total amount of the spin fluid.

[0072] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotropic or azeotrope-like composition consisting essentially of or consisting of from about 61 to about 85 weight percent trans- 1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, or from about 71 to about 85 weight percent trans-1 ,2-dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0073] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotropic composition consisting essentially of or consisting of from about 78 to about 82 weight percent trans-1 ,2-dichloroethylene and from about 22 to about 18 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at temperature of from about 40 °C to about 100 °C and at a boiling pressure of from about 80 kPa to about 459 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 81.5 weight percent trans- 1 ,2-dichloroethylene and about 18.5 weight percent 1 H,1 H,2H- heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 40 °C and at a boiling pressure of about 80.3 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 80.0 weight percent trans- 1 ,2-dichloroethylene and about 20.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 60 °C and at a boiling pressure of about 155.6 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 79.0 weight percent trans-1 ,2-dichloroethylene and about 21.0 weight percent 1 H,1 H,2H- heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 80 °C and at a boiling pressure of about 276.7 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 78.0 weight percent trans-1 ,2- dichloroethylene and about 22.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 100 °C and at a boiling pressure of about 459 kPa. In some embodiments, the azeotropic composition consists essentially of or consists of about 81.1 weight percent trans- 1 ,2-dichloroethylene and about 18.9 weight percent 1 H,1 H,2H-heptafluorocyclopentane. This azeotropic composition boils at a temperature of about 46.7 °C and at a boiling pressure of about 101.3 kPa.

[0074] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope- 1 ike composition consisting essentially of or consisting of from about 65 to about 85 weight percent trans- 1 ,2-dichloroethylene, and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H- decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent or about 5 weight percent, and the minimum amount of 2H,3H- decafluoropentane is about 2 weight percent or about 5 weight percent, each based on the total amount of the azeotrope- 1 ike composition.

[0075] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope- 1 ike composition consisting essentially of or consisting of from about 70 to about 85 weight percent, or about 70 to about 82 weight percent trans- 1 ,2-dichloroethylene, and from about 30 to about 15 weight percent, or from about 30 to about 18 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent or about 5 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent or about 5 weight percent, each based on the total amount of the azeotrope-like composition.

[0076] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotrope-like composition consisting essentially of or consisting of from about 75 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H- decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent or about 5 weight percent, and the minimum amount of 2H,3H- decafluoropentane is about 2 weight percent or about 5 weight percent, each based on the total amount of the azeotrope- 1 ike composition.

[0077] In some embodiments, the spin agent comprises, consists essentially of, or consists of an azeotropic or azeotrope- 1 ike composition consisting essentially of or consisting of about 80 weight percent trans- 1 ,2-dichloroethylene, about 10 weight percent 1 H,1 H,2H- heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, in other embodiments of about 75 weight percent trans-1 ,2-dichloroethylene, about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane and in other embodiments of about 75 weight percent trans-1 , 2-dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 15 weight percent 2H,3H- decafluoropentane.

[0078] The spin fluid may include additives, such as antioxidants or acid scavengers in minor amounts, provided that their presence does not interfere with the azeotropic or azeotrope-like nature of the compositions of trans- 1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane or of the compositions of trans-1 , 2-dichloroethylene, and 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane described herein. 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 agent, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin agent.

[0079] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 61 to about 85 weight percent trans-1 , 2- dichloroethylene and from about 39 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane, or from about 71 to about 85 weight percent trans-1 , 2- dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0080] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 65 to about 85 weight percent, or from about 70 to about 85 weight percent, or from about 70 to about 82 weight percent, or from about 75 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 35 to about 15 weight percent, or from about 30 to about 15 weight percent or from about 30 to about 18 weight percent or from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent, each based on the total amount of the azeotrope-like composition.

[0081] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 65 to about 85 weight percent, or from about 70 to about 85 weight percent, or from about 70 to about 82 weight percent, or from about 75 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 35 to about 15 weight percent, or from about 30 to about 15 weight percent or from about 30 to about 18 weight percent or from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 5 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 5 weight percent, each based on the total amount of the azeotrope-like composition.

[0082] Particularly preferred polyethylenes are 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).

[0083] In some embodiments, the PE blend comprises from about 50 to less than about 100 weight percent, or from about 70 to about 99 weight percent, or from about 70 to about 95 weight percent, or from about 80 to about 95 weight percent of polyethylene, and from about 50 to more than about 0 weight percent, or from about 30 to about 1 weight percent, or from about 30 to about 5 weight percent, or from about 20 to about 5 weight percent, of one or more other polyolefins, such as polypropylene.

[0084] In some embodiments, there is provided plexifilamentary fibrils of polyethylene or polyethylene blend obtainable by the process described herein.

[0085] The shape of the assembly of plexifilamentary fibrils of polyethylene or polyethylene blend discharged from each spin orifice may be modified by any methods known in the art. In some embodiments, the plexifilamentary fibrils of polyethylene or polyethylene blend 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 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.

[0086] Preparation of Sheets of Nonwoven Flash-spun Plexifilamentary Fibrils by Collection, Consolidation, Bonding, Softening, and Articles Made from Sheets of Nonwoven Flash-spun Plexifilamentary Fibrils

[0087] Sheets comprising plexifilamentary fibrils of polyethylene or polyethylene blend 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 collected sheet of nonwoven flash-spun plexifilamentary fibrils, 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 3,456,156, 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 WO92 / 20511. The stream of fibrils may also be laid down to form a collected sheet of nonwoven flash-spun plexifilamentary fibrils without deflection as described in US 5,788,993 and US 8,114,325. The method of forming a collected sheet of nonwoven flash-spun plexifilamentary fibrils may further utilize structures in the spin cell such as those described in US 5,123,983, US 5,296,172, and WO92 / 20511.

[0088] 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.

[0089] In some embodiments, the collected sheet of nonwoven flash-spun plexifilamentary fibrils formed by flash-spinning as described herein may be consolidated by applying a small amount of pressure to the sheet to form a consolidated sheet of nonwoven flash-spun plexifilamentary fibrils. In some embodiments, the sheet may be passed under a roller which applies pressure to the sheet to form a consolidated sheet.

[0090] In some embodiments, a consolidated sheet as described herein is subjected to thermal or mechanical bonding as known in the art to form a thermally or mechanically bonded sheet. Bonding may also be achieved by impregnation of a consolidated sheet with a chemical bonding agent, either throughout the entire sheet, or at isolated points distributed over the sheet, or pattern-wise.

[0091] In some embodiments, the bonded sheet is subjected to a mechanical softening process to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0092] In some embodiments, an antistatic treatment is applied to the bonded or softened sheet. In some embodiments, the antistatic treatment is applied by applying a coating composition comprising an antistatic compound.

[0093] 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. In some embodiments, the sheet of nonwoven flash-spun plexifilamentary fibrils as described herein is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

[0094] The sheet of nonwoven flash-spun plexifilamentary fibrils as described herein has many uses and may be used in a variety of articles and applications, including, but not limited to, multilayer structures, garments (including, but not limited to, protective apparel), house wrap, roof lining, car covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories.

[0095] EXAMPLES

[0096] A study has been performed for the flash spinning of polyethylene, for azeotropic or azeotrope- 1 ike compositions of trans-1 ,2-dichloroethylene and 1 H,1 H,2H- heptafluorocyclopentane or of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane. 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 any way.

[0097] Materials Used

[0098] Trans- 1 ,2-dichloroethylene (trans-DCE), CAS No. 156-60-5 has an atmospheric boiling point of 47.7 °C and a molecular weight of 96.9 g / mol. The trans-1 ,2-dichloroethylene used had a purity level above 99.9 percent by weight. 1 H,1 H,2H-heptafluorocyclopentane (HFCP, also known as 1 , 1 ,2, 2, 3,3,4- heptafluorocyclopentane), CAS No. 15290-77-4, has a melting point of 21 °C, an atmospheric boiling point of 82.5 °C, and a molecular weight of 196.07 g / mol. The 1 H,1 H,2H- heptafluorocyclopentane used had a purity level above 99 percent by weight.

[0099] 2H,3H-decafluoropentane (HFC-4310-mee, also known as 1 , 1 ,1 , 2, 2, 3, 4, 5,5,5- decafluoropentane), CAS No. 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.

[0100] Three different polyethylenes have been used

[0101] The polyethylene A used was a polyethylene having a density of 0.957 g / cm3(ISO 1183), a melting point of 134 °C, and a melt flow rate of 0.27 g / 10min (ISO 1133, - 190 °C / 2.16 kg).

[0102] The polyethylene B used was a polyethylene having a density of 0.951 g / cm3(ISO 1183), a melting point of 135 °C, and a melt flow rate of 8.4 g / 10min (ISO 1133 - 190 °C / 21.6 kg).

[0103] The polyethylene C used was a polyethylene having a density above 0.95 g / cm3(ISO 1183), a melting point of 133 °C, and a melt flow rate of 0.74 g / 10min (ISO 1133 - 190 “C / 2.16 kg).

[0104] The polyethylene was dried during a minimum of 8 hours in a vacuum oven at about 45-50 °C before use.

[0105] Spinning Equipment

[0106] The apparatus used consisted of two high pressure cylindrical chambers, each equipped with a piston which was adapted to apply pressure to the contents of the vessel. The cylinders had an inside diameter of 1.0 inch (25.4 mm) and each had an internal capacity of 50 cubic centimeters. The cylinders were connected to each other at one end through a 3 / 32 inch (2.3 mm) diameter channel and a mixing chamber containing a series of fine mesh screens was used as a static mixer. In the channel, a Type J thermocouple was in contact with the spin fluid to record the temperature. Mixing was accomplished by forcing the contents of the vessel back and forth between the two cylinders through the static mixer. A spinneret assembly with a quick-acting means for opening the orifice was attached to the channel through a tee. The spinneret assembly consisted of a lead hole with a diameter of 0.25 inch (6.3 mm) and a length of about 2.0 inch (50.8 mm), and a spinneret orifice with a diameter of 0.030 inch (0.762 mm) and a length of 0.030 inch (0.762 mm). A pressure transmitter calibrated at the spin temperature was mounted in the lead hole to measure the pressure of the spin fluid. The pistons were driven by a high-pressure hydraulic system. In operation, the apparatus was charged with polymer pellets and spin agent and a pressure of at least 50 bar was applied to the pistons to compress the charge and avoid the spin fluid from boiling during subsequent heating. The contents were then heated to mixing temperature and held at that temperature for about 30 to 45 minutes during which time a differential pressure was alternatively established between the two cylinders to repeatedly force the contents through the mixing channel from one cylinder to the other to provide mixing and effective formation of a spin fluid. The spin fluid temperature was then increased to the final spin temperature and held there for about 10 to 20 minutes to equilibrate. The pressure of the spin fluid was kept above the cloud point pressure during mixing and during the increase in temperature from the mixing temperature to the spin temperature. Mixing was continued throughout this period. At the end of the mixing cycle, the accumulator was set to the pressure desired for spinning. Next, the valve between the accumulator and the twin piston assembly was opened to reduce the pressure of the spin fluid to the desired spin pressure, and about two to five seconds later, the spinneret orifice was opened to release the spin fluid into conditions of atmospheric pressure. The delay of about two to five seconds corresponds to the residence time in the letdown chamber in a continuous spinning process. The resultant stream of flash-spun fibrils was collected in a stainless-steel open mesh screen basket. During spinning, the spin pressure was recorded just upstream of the spinneret.

[0107] For cloud point pressure determination, the spinneret assembly was replaced with a view cell assembly containing a 1 / 2 inch (12.3 mm) diameter high-pressure sight glass, through which the contents of the cell could be viewed as they flow through the channel. The window was lit by means of a fiber optic light guide, while the view through the sight glass was displayed using a digital camera. In the cell, a Type J thermocouple was located about 5 mm behind the high-pressure sight glass. The Type J thermocouple and a pressure measuring device located in close proximity to the window measured the pressure and temperature inside the view cell behind the sight glass and the pressure and temperature were continuously monitored by a computer. When, after a period of mixing, a clear, homogeneous spin fluid was established, the temperature was held constant and the differential pressure applied to the pistons was equalized so that the pistons stopped moving. Then, the pressure applied to the spin fluid in the view cell was gradually decreased until phase separation was observed through the sight glass, as the initially clear, homogeneous spin fluid became cloudy in appearance. The temperature and pressure were recorded when the thermocouple became no longer visible. This pressure was the phase separation pressure or cloud point pressure for that spin fluid at that temperature. The pressure was then increased until the spin fluid returned to its transparent state, i.e., until the insoluble phase redissolved, and in this way, two or three repeat cloud point measurements could be made at an approximately constant temperature. Once this data was recorded, mixing was resumed while the spin fluid was heated to the next temperature at which the cloud point pressure was to be measured.

[0108] Results

[0109] Example 1: Cloud point pressure study of polyethylene

[0110] Figure 1 shows the cloud point pressure curve of a spin fluid comprising 14 wt% polyethylene A and a spin agent of trans- 1,2-dichloroethylene and 1 H,1H,2H- heptafluorocyclopentane in a 82:18 ratio by weight. This spin fluid comprising 14 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0111] Example 2: Flash spinning performance of polyethylene

[0112] Flash spinning was performed on the equipment described in the above using a spin fluid comprising 14 wt% polyethylene A and a spin agent of trans- 1,2-dichloroethylene and 1H,1H,2H-heptafluorocyclopentane in a 82:18 ratio by weigh at a spin temperature of about 230 °C and a spin pressure of about 57 bar.

[0113] Example 3: Cloud point pressure study of polyethylene

[0114] Figure 2 shows the cloud point pressure curve of a spin fluid comprising 14 wt% polyethylene A and a spin agent of trans-1,2-dichloroethylene,1H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 80:10:10 ratio by weight. This spin fluid comprising 14 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0115] Example 4: Flash spinning performance of polyethylene

[0116] Flash spinning was performed on the equipment described in the above using a spin fluid comprising 14 wt% polyethylene A and a spin agent of trans-1,2-dichloroethylene, 1H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 80:10:10 ratio by weight at a spin temperature of about 200 °C and a spin pressure of about 50 bar.

[0117] Example 5: Cloud point pressure study of polyethylene

[0118] Figure 3 shows the cloud point pressure curve of a spin fluid comprising 14 wt% polyethylene A and a spin agent of trans-1,2-dichloroethylene, 1 H,1H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:15:10 ratio by weight. This spin fluid comprising 14 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0119] Example 6: Flash spinning performance of polyethylene

[0120] Flash spinning was performed on the equipment described in the above using a spin fluid comprising 14 wt% polyethylene A and a spin agent of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:15:10 ratio by weight at a spin temperature of about 190 °C and a spin pressure of about 45 bar.

[0121] Example 7: Cloud point pressure study of polyethylene

[0122] Figure 4 shows the cloud point pressure curve of spin fluid comprising 8 wt% polyethylene B and a spin agent of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:10:15 ratio by weight. This spin fluid comprising 8 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0123] Example 8: Flash spinning performance of polyethylene

[0124] Flash spinning was performed on the equipment described in the above using a spin fluid comprising 8 wt% polyethylene B and a spin agent of trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:10:15 ratio by weight at a spin temperature of about 200 °C and a spin pressure of about 133 bar.

[0125] Example 9: Cloud point pressure study of polyethylene

[0126] Figure 4 shows the cloud point pressure curve of spin fluid comprising 18 wt% polyethylene C and a spin agent of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H- heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:10:15 ratio by weight. This spin fluid comprising 18 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning. Example 10: Flash spinning performance of polyethylene

[0127] Flash spinning was performed on the equipment described in the above using a spin fluid comprising 18 wt% polyethylene C and a spin agent of trans- 1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane in a 75:10:15 ratio by weight at a spin temperature of about 210 °C and a spin pressure of about 127 bar.

[0128] Table 1 : Summary of the flash spin experiments of Examples 2, 4, 6, 8, and 10.

[0129] * calculated based on an assumed GWP of about 5 for the trans-1 ,2-dichloroethylene, as well as a GWP of 231 for 1 H,1 H,2H-heptafluorocyclopentane and a GWP of 1600 for 2H,3H- decafluoropentane based on the IPCC 2021 report (global warming potential over a 100-year period)

[0130] The above examples illustrate that the azeotropic or azeotrope-like compositions can be used as a spin agent for the flash spinning process of polyethylene for different spin temperatures and spin pressures. This allows an efficient preparation of plexifilamentary fibrils of polyethylene.

[0131] In addition, the azeotropic or azeotrope-like compositions exhibit a desirably low GWP value of below 300. This makes these compositions suitable as replacement for currently used spin agents.

[0132] Furthermore, the azeotropic or azeotrope- 1 ike compositions form a positive homogenous azeotrope with an advantageously low boiling temperature of about 50 °C. Such low boiling temperature correlates to a pressure at or around atmospheric pressure. The azeotrope- 1 ike compositions exhibit only small differences between the bubble point pressure and the dew point pressure and / or only small variations in the bubble point pressure between the original composition and the composition remaining after 50 weight percent of the original composition has been removed by evaporation or boil off. This has the advantage that the azeotropic or azeotrope-like compositions do not change significantly during the different steps of the spin agent recovery process and thus allow the spin agent to be re-used / recycled in a commercial process.

[0133] OTHER EMBODIMENTS

[0134] 1. In some embodiments, the present application provides a spin fluid for flash spinning comprising

[0135] (a) from about 6 to about 24 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and

[0136] (b) a spin agent, wherein the spin agent comprises

[0137] (1) an azeotropic or azeotrope-like composition comprising trans-1 ,2- dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or

[0138] (2) an azeotrope-like composition comprising trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0139] 2. The spin fluid of embodiment 1 comprising about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, each based on the total amount of the spin fluid.

[0140] 3. The spin fluid of embodiment 1 or 2 comprising from about 76 to about 94 weight percent of the spin agent, or from about 80 to about 94 weight percent of the spin agent, or from about 80 to about 92 weight percent of the spin agent, or from about 84 to about 92 weight percent of the spin agent, or from about 86 to about 92 weight percent of the spin agent, each based on the total amount of the spin fluid.

[0141] 4. The spin fluid of any of embodiments 1 to 3, wherein the polyethylene is a high-density polyethylene (HDPE), a blend / mixture of a high-density polyethylene (HDPE) with a low- density polyethylene (LDPE), or a blend / mixture of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE). 5. The spin fluid of any of embodiments 1 to 4, wherein the spin agent comprises, consists essentially of or consists of an azeotropic or azeotrope-like composition comprising trans-1 ,2- dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane.

[0142] 6. The spin fluid of embodiment 5, wherein the azeotropic or azeotrope-like composition comprises, consists essentially of, or consists of from about 61 to about 85 weight percent trans-1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0143] 7. The spin fluid of embodiment 5 or 6, wherein the azeotropic or azeotrope-like composition comprises, consists essentially of, or consists of from about 71 to about 85 weight percent trans- 1 ,2-dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0144] 8. The spin fluid of any of embodiment 5 to 7, wherein the azeotropic composition comprises, consists essentially of or consists of from about 78 to about 82 weight percent trans-1 ,2-dichloroethylene and from about 22 to about 18 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0145] 9. The spin fluid of embodiment 8, wherein the azeotropic composition boils at a temperature of about 40 °C to about 100 °C and at a boiling pressure of from about 80 kPa to about 459 kPa.

[0146] 10. The spin fluid of any of embodiment 5 to 9, wherein the azeotropic composition comprises, consists essentially of or consists of about 81.5 weight percent trans-1 ,2- dichloroethylene and about 18.5 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0147] 11. The spin fluid of embodiment 10, wherein the azeotropic composition boils at a temperature of about 40 °C and at a boiling pressure of about 80.3 kPa.

[0148] 12. The spin fluid of any of embodiment 5 to 9, wherein the azeotropic composition comprises, consists essentially of or consists of about 80.0 weight percent trans-1 ,2- dichloroethylene and about 20.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0149] 13. The spin fluid of embodiment 12, wherein the azeotropic composition boils at a temperature of about 60 °C and at a boiling pressure of about 155.6 kPa. 14. The spin fluid of any of embodiment 5 to 9, wherein the azeotropic composition comprises, consists essentially of or consists of about 79.0 weight percent trans-1 ,2- dichloroethylene and about 21.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0150] 15. The spin fluid of embodiment 14, wherein the azeotropic composition boils at a temperature of about 80 °C and at a boiling pressure of about 276.7 kPa.

[0151] 16. The spin fluid of any of embodiment 5 to 9, wherein the azeotropic composition comprises, consists essentially of or consists of about 78.0 weight percent trans-1 ,2- dichloroethylene and about 22.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0152] 17. The spin fluid of embodiment 16, wherein the azeotropic composition boils at a temperature of about 100 °C and at a boiling pressure of about 459 kPa.

[0153] 18. The spin fluid of any of embodiment 5 to 9, wherein the azeotropic composition comprises, consists essentially of or consists of about 81.1 weight percent trans-1 ,2- dichloroethylene and about 18.9 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0154] 19. The spin fluid of embodiment 18, wherein the azeotropic composition boils at a temperature of about 46.7 °C and at a boiling pressure of about 101.3 kPa.

[0155] 20. The spin fluid of any of embodiments 1 to 4, wherein the spin agent comprises, consists essentially of or consists of an azeotrope-like composition comprising trans-1 ,2- dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0156] 21. The spin fluid of embodiment 20, wherein the azeotrope-like composition comprises, consists essentially of, or consists of from about 65 to about 85 weight percent trans-1 ,2- dichloroethylene, and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0157] 22. The spin fluid of any of embodiment 21 , wherein the azeotrope- 1 ike composition comprises, consists essentially of, or consists of from about 70 to about 85 weight percent, or about 70 to about 82 weight percent trans- 1 ,2-dichloroethylene, and from about 30 to about 15 weight percent, or from about 30 to about 18 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane. 23. The spin fluid of any of embodiment 21 or 22, wherein the azeotrope-like composition comprises, consists essentially of, or consists of from about 75 to about 82 weight percent trans- 1,2-dichloroethylene, and from about 18 to about 25 weight percent of a combination of 1 H,1H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0158] 24. The spin fluid of any of embodiment 20 to 23, wherein the minimum amount of 1 H,1H,2H-heptafluorocyclopentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0159] 25. The spin fluid of embodiment 24, wherein the minimum amount of 1 H,1H,2H- heptafluorocyclopentane is about 5 weight percent, based on the total amount of the azeotrope- 1 ike composition.

[0160] 26. The spin fluid of any of embodiments 20 to 25, wherein the minimum amount of the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0161] 27. The spin fluid of embodiment 26, wherein the minimum amount of 2H,3H- decafluoropentane is about 5 weight percent, based on the total amount of the azeotrope-like composition.

[0162] 28. The spin fluid of any of embodiments 20 to 27, wherein the azeotrope-like composition comprises, consists essentially of, or consists of about 80 weight percent trans-1,2- dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane.

[0163] 29. The spin fluid of any of embodiments 20 to 27, wherein the azeotrope-like composition comprises, consists essentially of, or consists of about 75 weight percent trans-1,2- dichloroethylene, about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane.

[0164] 30. The spin fluid of any of embodiments 20 to 27, wherein the azeotrope-like composition comprises, consists essentially of, or consists of about 75 weight percent trans-1,2- dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 15 weight percent 2H,3H-decafluoropentane. 31. The spin fluid of any of embodiments 1 to 19, wherein the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 61 to about 85 weight percent trans-1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H, 1 H,2H-heptafluorocyclopentane.

[0165] 32. The spin fluid of embodiments 31 , wherein the spin agent consists essentially of or consists of from about 71 to about 85 weight percent trans-1 ,2-dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0166] 33. The spin fluid of any of embodiments 1 to 4 or 20 to 30, wherein the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 65 to about 85 weight percent trans-1 ,2-dichloroethylene, and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0167] 34. The spin fluid of embodiment 33, wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent, or from about 70 to about 82 weight percent, or from about 75 to about 82 weight percent trans- 1 ,2-dichloroethylene, and from about 30 to about 15 weight percent or from about 30 to about 18 weight percent or from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0168] 35. The spin fluid of embodiment 33 or 34, wherein the minimum amount of 1 H,1 H,2H- heptafluorocyclopentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0169] 36. The spin fluid of embodiment 35, wherein the minimum amount of 1 H,1 H,2H- heptafluorocyclopentane is about 5 weight percent, based on the total amount of the azeotrope-like composition. 37. The spin fluid of any of embodiments 33 to 36, wherein the minimum amount of the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0170] 38. The spin fluid of embodiment 37, wherein the minimum amount of 2H,3H- decafluoropentane is about 5 weight percent, based on the total amount of the azeotrope-like composition.

[0171] 39. In some embodiments, the present application provides a process for the preparation of plexifilamentary fibrils of polyethylene or polyethylene blend which comprises the steps of:

[0172] (i) generating a spin fluid comprising

[0173] (a) from about 6 to about 24 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and

[0174] (b) a spin agent, and

[0175] (ii) flash spinning the spin fluid 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 polyethylene or polyethylene blend, wherein the spin agent comprises

[0176] (1) an azeotropic or azeotrope-like composition comprising trans-1 ,2- dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or

[0177] (2) an azeotrope-like composition comprising trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0178] 40. The process of embodiment 39, wherein the spin fluid comprises about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, each based on the total amount of the spin fluid.

[0179] 41. The process of embodiment 39 or 40, wherein the spin fluid comprises from about 76 to about 94 weight percent of the spin agent, or from about 80 to about 94 weight percent of the spin agent, or from about 80 to about 92 weight percent of the spin agent, or from about 84 to about 92 weight percent of the spin agent, or from about 86 to about 92 weight percent of the spin agent, each based on the total amount of the spin fluid.

[0180] 42. The process of any of embodiments 39 to 41 , wherein the polyethylene is a high- density polyethylene (HDPE), a blend / mixture of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE), or a blend / mixture of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE). 43. The process of any of embodiments 39 to 42, wherein the spin agent comprises, consists essentially of or consists of an azeotropic or azeotrope-like composition comprising trans-1 ,2-dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane.

[0181] 44. The process of embodiment 43, wherein the azeotropic or azeotrope-like composition comprises, consists essentially of, or consists of from about 61 to about 85 weight percent trans-1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0182] 45. The process of embodiment 43 or 44, wherein the azeotropic or azeotrope- 1 ike composition comprises, consists essentially of, or consists of from about 71 to about 85 weight percent trans- 1 ,2-dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0183] 46. The process of any of embodiment 43 to 45, wherein the azeotropic composition comprises, consists essentially of or consists of from about 78 to about 82 weight percent trans-1 ,2-dichloroethylene and from about 22 to about 18 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

[0184] 47. The process of embodiment 46, wherein the azeotropic composition boils at a temperature of about 40 °C to about 100 °C and at a boiling pressure of from about 80 kPa to about 459 kPa.

[0185] 48. The process of any of embodiment 43 to 47, wherein the azeotropic composition comprises, consists essentially of or consists of about 81.5 weight percent trans-1 ,2- dichloroethylene and about 18.5 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0186] 49. The process of embodiment 48, wherein the azeotropic composition boils at a temperature of about 40 °C and at a boiling pressure of about 80.3 kPa.

[0187] 50. The process of any of embodiment 43 to 47, wherein the azeotropic composition comprises, consists essentially of or consists of about 80.0 weight percent trans-1 ,2- dichloroethylene and about 20.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0188] 51. The process of embodiment 50, wherein the azeotropic composition boils at a temperature of about 60 °C and at a boiling pressure of about 155.6 kPa. 52. The process of any of embodiment 43 to 47, wherein the azeotropic composition comprises, consists essentially of or consists of about 79.0 weight percent trans-1 ,2- dichloroethylene and about 21.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0189] 53. The process of embodiment 52, wherein the azeotropic composition boils at a temperature of about 80 °C and at a boiling pressure of about 276.7 kPa.

[0190] 54. The process of any of embodiment 43 to 47, wherein the azeotropic composition comprises, consists essentially of or consists of about 78.0 weight percent trans-1 ,2- dichloroethylene and about 22.0 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0191] 55. The process of embodiment 54, wherein the azeotropic composition boils at a temperature of about 100 °C and at a boiling pressure of about 459 kPa.

[0192] 56. The process of any of embodiment 43 to 47, wherein the azeotropic composition comprises, consists essentially of or consists of about 81.1 weight percent trans-1 ,2- dichloroethylene and about 18.9 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0193] 57. The process of embodiment 56, wherein the azeotropic composition boils at a temperature of about 46.7 °C and at a boiling pressure of about 101.3 kPa.

[0194] 58. The process of any of embodiments 39 to 42, wherein the spin agent comprises, consists essentially of or consists of an azeotrope- 1 ike composition comprising trans-1 ,2- dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

[0195] 59. The process of embodiment 58, wherein the azeotrope-like composition comprises, consists essentially of, or consists of from about 65 to about 85 weight percent trans-1 ,2- dichloroethylene, and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0196] 60. The process of any of embodiment 59, wherein the azeotrope-like composition comprises, consists essentially of, or consists of from about 70 to about 85 weight percent, or about 70 to about 82 weight percent trans- 1 ,2-dichloroethylene, and from about 30 to about 15 weight percent, or from about 30 to about 18 weight percent of a combination of 1 H,1 H,2H- heptafluorocyclopentane and 2H,3H-decafluoropentane. 61. The process of any of embodiment 59 or 60, wherein the azeotrope-like composition comprises, consists essentially of, or consists of from about 75 to about 82 weight percent trans-1 ,2-dichloroethylene, and from about 18 to about 25 weight percent of a combination of 1H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0197] 62. The process of any of embodiment 58 to 61, wherein the minimum amount of 1H,1 H,2H-heptafluorocyclopentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0198] 63. The process of embodiment 62, wherein the minimum amount of 1H,1 H,2H- heptafluorocyclopentane is about 5 weight percent, based on the total amount of the azeotrope-like composition.

[0199] 64. The process of any of embodiments 58 to 63, wherein the minimum amount of the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0200] 65. The process of embodiment 64, wherein the minimum amount of 2H,3H- decafluoropentane is about 5 weight percent, based on the total amount of the azeotrope-like composition.

[0201] 66. The process of any of embodiments 58 to 65, wherein the azeotrope- 1 ike composition comprises, consists essentially of, or consists of about 80 weight percent trans-1, 2- dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane.

[0202] 67. The process of any of embodiments 58 to 65, wherein the azeotrope- 1 ike composition comprises, consists essentially of, or consists of about 75 weight percent trans-1, 2- dichloroethylene, about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane.

[0203] 68. The process of any of embodiments 58 to 65, wherein the azeotrope- 1 ike composition comprises, consists essentially of, or consists of about 75 weight percent trans-1, 2- dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 15 weight percent 2H,3H-decafluoropentane. 69. The process of any of embodiments 39 to 57, wherein the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 61 to about 85 weight percent trans-1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H, 1 H,2H-heptafluorocyclopentane.

[0204] 70. The process of embodiments 69, wherein the spin agent consists essentially of or consists of from about 71 to about 85 weight percent trans- 1,2-dichloroethylene and from about 29 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0205] 71. The process of any of embodiments 39 to 42 or 58 to 68, wherein the spin fluid comprises about 6 to about 24 weight percent, or about 6 to about 20 weight percent, or about 8 to about 20 weight percent, or about 8 to about 16 weight percent, or about 8 to about 14 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of or consists of from about 65 to about 85 weight percent trans- 1 ,2-dichloroethylene, and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H- decafluoropentane.

[0206] 72. The process of embodiment 71 , wherein the spin agent consists essentially of or consists of from about 70 to about 85 weight percent, or from about 70 to about 82 weight percent, or from about 75 to about 82 weight percent trans- 1 ,2-dichloroethylene, and from about 30 to about 15 weight percent or from about 30 to about 18 weight percent or from about 25 to about 18 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane.

[0207] 73. The process of embodiment 71 or 72, wherein the minimum amount of 1 H,1 H,2H- heptafluorocyclopentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0208] 74. The process of embodiment 73, wherein the minimum amount of 1 H,1 H,2H- heptafluorocyclopentane is about 5 weight percent, based on the total amount of the azeotrope-like composition. 75. The process of any of embodiments 71 to 74, wherein the minimum amount of the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent, based on the total amount of the azeotrope-like composition.

[0209] 76. The process of embodiment 75, wherein the minimum amount of 2H,3H- decafluoropentane is about 5 weight percent, based on the total amount of the azeotrope-like composition.

[0210] 77. In some embodiments, the present application provides a use of the spin fluid of any of embodiments 1 to 38 for preparing of plexifilamentary fibrils of polyethylene or polyethylene blend by flash spinning.

[0211] 78. The plexifilamentary fibrils of polyethylene or polyethylene blend obtainable by the process of any one of embodiments 39 to 76.

[0212] 79. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polyethylene or polyethylene blend of embodiment 78.

[0213] 80. The sheet of embodiment 79, wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

[0214] 81. A bonded sheet obtainable by thermally or mechanically bonding the consolidated sheet of embodiment 80.

[0215] 82. A softened sheet obtainable by softening the consolidated sheet of embodiment 124 or by softening the bonded sheet of embodiment 81.

[0216] 83. A multilayer sheet comprising two or more sheets wherein at least one sheet is a sheet according to any one of embodiments 79 to 82.

[0217] 84. An article comprising plexifilamentary fibrils of polyethylene or polyethylene blend of embodiment 78 and / or a sheet of any one of embodiments 79 to 82 and / or a multilayer sheet of embodiment 83.

[0218] 85. The article of embodiment 84 which is selected from garment, protective apparel, house wrap, roof lining, car covers, cargo covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories. 86. The article of embodiment 85 wherein the garment is protective apparel. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope of the present invention. Thus, it should be appreciated that, while the invention has been described with reference to the above exemplary embodiments, other embodiments are within the scope of the claims.

[0219] Moreover, it should be understood that the exemplary embodiments described herein may be combined to form other embodiments. After reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement the invention in alternative embodiments. Thus, the present invention should not be limited by any of the above-described exemplary embodiments.

Claims

CLAIMS1. A spin fluid for flash spinning comprising(a) from about 6 to about 24 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and(b) a spin agent, wherein the spin agent comprises(1) an azeotropic or azeotrope-like composition comprising trans-1 , 2- dichloroethylene and 1H,1 H,2H-heptafluorocyclopentane, or(2) an azeotrope- 1 ike composition comprising trans-1,2-dichloroethylene, 1H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

2. The spin fluid of claim 1 comprising from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 80 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid.

3. The spin fluid of claims 1 or 2, wherein the polyethylene is selected from the group consisting of high-density polyethylene (HDPE) and blends / mixtures of high-density polyethylene (HDPE) with low-density polyethylene (LDPE).

4. The spin fluid of any one of claims 1 to 3, wherein the spin agent comprises an azeotropic or azeotrope-like composition consisting essentially of from about 61 to about 85 weight percent trans- 1,2-dichloroethylene and from about 39 to about 15 weight percent 1 H, 1 H,2H-heptafluorocyclopentane.

5. The spin fluid of claim 4, wherein the spin agent comprises an azeotropic or azeotropelike composition consisting essentially of from about 78 to about 82 weight percent trans-1 ,2- dichloroethylene and from about 22 to about 18 weight percent 1 H,1H,2H- heptafluorocyclopentane.

6. The spin fluid of any one of claims 1 to 3, wherein the spin agent comprises an azeotropic or azeotrope-like composition consisting essentially of from about 65 to about 85 weight percent trans-1, 2-dichloroethylene and from about 35 to about 15 weight percent of a combination of 1 H,1H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane, wherein the minimum amount of 1H,1 H,2H-heptafluorocyclopentane is about 2 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent.

7. The spin fluid of claim 6, wherein the spin agent comprises an azeotropic or azeotropelike composition consisting essentially of about 80 weight percent trans-1 ,2-dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, or consisting essentially of about 75 weight percent trans-1 ,2- dichloroethylene, about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, or consisting essentially of about 75 weight percent trans-1 ,2-dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 15 weight percent 2H,3H-decafluoropentane.

8. A process for the preparation of plexifilamentary fibrils of polyethylene or polyethylene blend which comprises the steps of:(i) generating a spin fluid comprising(a) from about 6 to about 24 weight percent of a polyethylene or a polyethylene blend, based on the total amount of the spin fluid, and(b) a spin agent, and(ii) flash spinning the spin fluid 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 polyethylene or polyethylene blend, wherein the spin agent comprises(1) an azeotropic or azeotrope-like composition comprising trans-1 ,2- dichloroethylene and 1 H,1 H,2H-heptafluorocyclopentane, or(2) an azeotrope-like composition comprising trans-1 ,2-dichloroethylene, 1 H,1 H,2H-heptafluorocyclopentane, and 2H,3H-decafluoropentane.

9. The process of claim 8, wherein the spin fluid comprises from about 76 to about 94 weight percent of the spin agent, based on the total amount of the process, or from about 80 to about 94 weight percent of the spin agent, based on the total amount of the process.

10. The process of claims 8 or 9, wherein the polyethylene is selected from the group consisting of high-density polyethylene (HDPE) and blends / mixtures of high-density polyethylene (HDPE) with low-density polyethylene (LDPE).

11. The process of any one of claims 8 to 10, wherein the spin agent comprises an azeotropic or azeotrope-like composition consisting essentially of from about 61 to about 85 weight percent trans- 1 ,2-dichloroethylene and from about 39 to about 15 weight percent 1 H, 1 H,2H-heptafluorocyclopentane.

12. The process of claim 11 , wherein the spin agent comprises an azeotropic or azeotropelike composition consisting essentially of from about 78 to about 82 weight percent trans-1 ,2- dichloroethylene and from about 22 to about 18 weight percent 1 H,1 H,2H- heptafluorocyclopentane.

13. The process of any one of claims 8 to 10, wherein the spin agent comprises an azeotropic or azeotrope-like composition consisting essentially of from about 65 to about 85 weight percent trans-1 , 2-dichloroethylene and from about 35 to about 15 weight percent of a combination of 1 H,1 H,2H-heptafluorocyclopentane and 2H,3H-decafluoropentane, wherein the minimum amount of 1 H,1 H,2H-heptafluorocyclopentane is about 2 weight percent, and the minimum amount of 2H,3H-decafluoropentane is about 2 weight percent.

14. The process of claim 13, wherein the spin agent comprises an azeotropic or azeotropelike composition consisting essentially of about 80 weight percent trans-1 , 2-dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, or consisting essentially of about 75 weight percent trans-1 , 2- dichloroethylene, about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 10 weight percent 2H,3H-decafluoropentane, or consisting essentially of about 75 weight percent trans-1 , 2-dichloroethylene, about 10 weight percent 1 H,1 H,2H-heptafluorocyclopentane, and about 15 weight percent 2H,3H-decafluoropentane.

15. Use of the spin fluid of any one of claims 1 to 7 for preparing of plexifilamentary fibrils of polyethylene or polyethylene blend by flash spinning.

16. Plexifilamentary fibrils of polyethylene or polyethylene blend obtainable by the process of any one of claims 8 to 14.

17. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polyethylene or polyethylene blend of claim 16.

18. The sheet of claim 17, wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

19. An article comprising the plexifilamentary fibrils of polyethylene or polyethylene blend of claim 15 and / or the sheet of claim 17 or claim 18.

20. The article of claim 19 which is selected from garment, protective apparel, packaging material, house wrap, roof lining, car covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories.

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