Non-azeotropic compositions comprising dichloromethane and 1h,1h,2h-heptafluorocyclopentane and use of the compositions as flash spinning agents

Abstract

The present invention relates to (i) a non-azeotropic composition comprising dichloromethane and 1H,1H,2H-heptafluorocyclopentane, (ii) a spin fluid for flash spinning comprising this non-azeotropic composition and a polymer, and (iii) a process for the preparation of plexifilamentary fibrils of polymers using the spin fluid.

Description

[0001] TITLE

[0002] NON-AZEOTROPIC COMPOSITIONS COMPRISING DICHLOROMETHANE AND 1 H, 1 H.2H-HEPTAFLUOROCYCLOPENTANE AND USE OF THE COMPOSITIONS AS FLASH SPINNING AGENTS

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to (i) a non-azeotropic composition comprising dichloromethane and 1 H,1 H,2H-heptafluorocyclopentane, (ii) a spin fluid for flash spinning comprising this non-azeotropic composition and a polymer, and (iii) a process for the preparation of plexifilamentary fibrils of polymers 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 3,081 ,519 and 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. During this step, it is preferred that the composition of the spin agent remains essentially constant. This is inherent when spin agents comprise only one solvent but not when spin agents comprise two or more solvents, which are often required to provide the necessary solvent properties for flash spinning the desired polymer. When a spin agent composition comprises two or more solvents, it is, in some instances, advantageous if that composition is zeotropic (i.e., not azeotropic or azeotrope-like). For example, when a spin agent composition is azeotropic or azeotrope-like, but at mixing ratios of its components which do not provide the necessary solvent properties for flash spinning the desired polymer, this complicates the spin agent recovery and re-use process. This is because the components of an azeotropic or azeotropic-like composition cannot be readily separated by distillation, whereas the components of a zeotropic composition can be readily separated by distillation and recombined into a spin agent in any desired ratio suitable for the polymer being flash spun.

[0008] One example of a commonly used solvent for polymers such as polyolefins is dichloromethane (DCM). DCM, however, is too strong of a solvent and cannot be used as the only component in a spin agent composition for flash spinning because it dissolves polymers at relatively low pressures. Weaker solvents such as fluorocarbons or hydrofluorocarbons can be mixed with DCM to reduce the solvent strength of the spin agent and to increase the spin fluid’s cloud point pressure such that flash spinning can be readily accomplished.

[0009] However, when a fluorocarbon or hydrofluorocarbon is added to DCM to form a spin agent composition, the cloud point pressure of the spin agent composition becomes very sensitive to the amount of fluorocarbon or hydrofluorocarbon in the spin agent composition and precise control of the spin agent composition becomes of great importance. This can most readily be achieved if DCM does not form an azeotrope with the non-DCM components used to control the cloud point pressure (i.e., DCM and the non-DCM components form a zeotrope) so that the spin agent vapor released in the flash-spinning process can be readily separated into its pure components on a distillation column, and these components can then be re-combined in whatever ratio is desired for their re-use in what becomes a relatively simple spin agent recovery and composition control process.

[0010] Another important factor to be considered when selecting components for spin agents is their global warming potential (GWP). Many of the fluorinated solvents that provide suitable cloud point pressures for flash-spinning when blended with dichloromethane, unfortunately have high GWPs. In view of the growing concerns regarding climate change and increasing regulatory requirements, there is a need to find suitable low GWP replacements for such spin agent compositions.

[0011] WO 2016 / 200873 A1 reports spin agent compositions of dichloromethane with 1H,6H- perfluorohexane, 1 H-perfluorohexane, or 1 H-perfluoroheptane, but these compositions are azeotropic or azeotrope-like and exhibit undesirably high global warming potential (GWP). US 5,672,307 reports a flash spinning process using spin agent compositions of dichloromethane with cyclic perfluorocarbons, such as perfluoro-1 ,2-dimethylcyclobutane, and perfluoro-N-methylmorpholine. US 5,874,036 and US 5,977,237 report a flash spinning process using spin agent compositions of dichloromethane 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 (having a boiling point of 79 °C). However, the disclosed compositions complicate the spin agent recovery process since (i) many of the disclosed fluorinated spin agent components are not miscible with DCM at ambient temperatures and pressures, and thus, upon condensation of the spin agent, a liquid phase separation of the two components occurs and the spin agent becomes a heterogeneous liquid, and / or (ii) the disclosed compositions form azeotropic or azeotrope-like compositions at ratios that are not ideal for flash spinning, leading to complications in recovering and reusing the spin agents, as described above.

[0012] Accordingly, there is a need for, and the present inventors have discovered compositions of dichloromethane and a hydrofluorocarbon that (i) have a low GWP, (ii) do not form an azeotrope and thus can be readily separated in a spin agent recovery process, and (iii) provide suitable cloud point pressures for flash spinning a broad range of different polymers and blends / mixtures thereof.

[0013] SUMMARY OF THE INVENTION

[0014] In one embodiment, the invention is directed to a non-azeotropic composition comprising dichloromethane and 1 H,1 H,2H-heptafluorocyclopentane.

[0015] In a further embodiment, the invention is directed to a spin fluid for flash spinning comprising (a) from about 5 to about 35 weight percent of a polymer, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises a non-azeotropic composition comprising dichloromethane and 1H,1 H,2H-heptafluorocyclopentane.

[0016] In a further embodiment, the invention is directed to a process for the preparation of plexifilamentary fibrils of polymer. The process comprises the steps of:

[0017] (i) generating a spin fluid comprising

[0018] (a) about 5 to about 35 weight percent of a polymer, based on the total amount of the spin fluid, and

[0019] (b) a spin agent, and

[0020] (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 polymer, wherein the spin agent comprises a non-azeotropic composition comprising dichloromethane and 1 H , 1 H ,2H-heptafluorocyclopentane.

[0021] BRIEF DESCRIPTION OF THE FIGURES

[0022] Fig. 1 shows the calculated vapor-liquid equilibrium (VLE) for the mixture dichloromethane and 1 H,1 H,2H-heptafluorocyclopentane.

[0023] Fig. 2 shows the cloud point pressure curve of a spin fluid comprising 10 wt% polypropylene (PP) and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 45:55 ratio by weight.

[0024] Fig. 3 shows the cloud point pressure curve of a spin fluid comprising 15 wt% polypropylene (PP) and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 40:60 ratio by weight.

[0025] Fig. 4 shows the cloud point pressure curve of a spin fluid comprising 10 wt% polyethylene (PE) and a spin agent of DCM and 1H,1 H,2H-heptafluorocyclopentane in a 72.5:27.5 ratio by weight.

[0026] Fig. 5 shows the cloud point pressure curve of a spin fluid comprising 6 wt% ethylenebutylene copolymer (EB) and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 75:25 ratio by weight.

[0027] Fig. 6 shows the cloud point pressure curve of a spin fluid comprising 17 wt% ethylenebutylene copolymer (EB) and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 75:25 ratio by weight.

[0028] Fig. 7 shows the cloud point pressure curve of a spin fluid comprising 26 wt% polyvinylidene fluoride (PVDF) and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 55:45 ratio by weight.

[0029] DETAILED DESCRIPTION

[0030] Definitions and Clarification of Terms

[0031] 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.

[0032] Density is determined according to the method described in ISO 1183 (Plastics - Methods for determining the density of non-cellular plastics). Melting temperature 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). Determination of the melting temperature of polyethylene is further described in ASTM Standard F2625 (Standard Test Method for Measurement of Enthalpy of Fusion, Percent Crystallinity and Melting Point of Ultra-High-Molecular weight polyethylene by means of differential scanning calorimetry). For polyethylene, heating and cooling is performed under inert gas at a rate of 10 °C / minute, heating the sample first from room temperature to 210 °C, then cooling the sample back to room temperature and subsequently heating the sample a second time to 210 °C. The melting point reported herein is the peak temperature of the endotherm of the second heating cycle. For polypropylene, the same procedure applies - where the maximum temperature is 230 °C.

[0033] 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 a temperature of 190 °C and using a mass of 2160 grams, 5000 grams (5kg) or 21 ,600 gram (21 ,6kg). The melt flow rate for polypropylene is determined at a temperature of 230 °C and using a mass of 2160 grams. The melt flow rates of other polyolefins are performed at different temperatures as specified in ISO 1133.

[0034] 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.

[0035] 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 high-density polyethylene that has a melting temperature of about 123 °C to about 140 °C, a density in the range of 0.94 to 0.98 grams per cubic centimeter, and a melt flow rate (ISO 1133, 190 °C / 2160 grams) of between 0.05 g / 10 min and 30 g / 10 min, preferably less than 4 g / 10 min, and / or a melt flow rate (ISO 1133, 190 °C / 21 ,600 grams) of between 1 g / 10min and 15 g / 10min.

[0036] The term “polypropylene” is intended to embrace not only homopolymers of propylene but also copolymers and terpolymers where at least 85% of the recurring units are propylene units. Furthermore, unless otherwise specifically limited, the term “polypropylene” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries.

[0037] The term “polyvinylidene fluoride” (PVDF) is intended to embrace not only homopolymers of vinylidene fluoride but also copolymers where at least 70% of the recurring units are vinylidene fluoride units.

[0038] The term “polymer type” refers to the chemical class into which the polymer falls, for example, polyethylene, polypropylene, polyvinylidene fluoride, etc.

[0039] 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.

[0040] The terms “spin agent” or “spin agent composition” refer 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.

[0041] The term “spin fluid” refers to a solution for spinning in a flash spinning process comprising a polymer and a spin agent. The solution may also include one or more additives.

[0042] 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.

[0043] The term “bubble point pressure” refers to the pressure at which, at constant temperature, a liquid, liquid mixture, or liquid-solution begins to boil.

[0044] 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.

[0045] The term “non-azeotropic composition,” also referred to as “zeotropic composition,” refers to a composition comprising two or more fluids that behaves as a mixture rather than a single substance over the whole composition range upon boiling. In a non-azeotropic composition, the bubble point pressure is substantially different from the dew point pressure over the entire composition range, and the components can be separated completely into pure substances by distillation. The non-azeotropic compositions described herein, unless expressly stated otherwise, are determined at 40 °C and expressed in mass fractions. 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.

[0046] Atmospheric pressure means 101.325 kPa. Essentially atmospheric pressure means 101.325 kPa ± 5 %.

[0047] 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.

[0048] Non-azeotropic Compositions

[0049] Provided herein are non-azeotropic compositions comprising dichloromethane and 1 H , 1 H ,2H-heptafluorocyclopentane.

[0050] In some embodiments, the non-azeotropic compositions comprise from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1H,1H,2H- heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[0051] In some embodiments, the non-azeotropic compositions consist essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane. In some embodiments, the non-azeotropic compositions consist of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[0052] The compound 1 H,1 H,2H-heptafluorocyclopentane has a reported GWP-100 (global warming potential over a 100-year period) of 231 (IPCC 2021 report) and dichloromethane (DCM) has a reported GWP-100 of 11.2 (IPCC 2021 report). Accordingly, the non-azeotropic compositions combining the two compounds have a low global warming potential (GWP). In some embodiments, the non-azeotropic compositions have a GWP-100 (global warming potential over a 100-year period) of less than 160, in other embodiments of less than 150, in other embodiments of less than 120, in other embodiments less than 80, and in other embodiments less than 60.

[0053] The non-azeotropic compositions as described herein have the advantage of being homogeneous non-azeotropic compositions. For homogenous compositions, the components of the composition at ambient temperatures and pressures form a single liquid phase. This is to be contrasted with heterogeneous compositions where the components of the composition undergo phase separation into two distinct liquid phases with different compositions. Phase separation is usually undesired since processes involving the composition are more complex and expensive. The homogeneous nature of the non-azeotropic compositions is achievable over a broad range of practical conditions including ambient pressure and temperature.

[0054] The non-azeotropic compositions are useful in a wide range of applications. In some embodiments, the non-azeotropic compositions are used as spin agents for flash spinning, in other embodiments as cleaning agents, and in other embodiments as solvents.

[0055] Spin Agents and Spin Fluids for Flash Spinning

[0056] In some embodiments, the non-azeotropic compositions are spin agents within spin fluids for flash spinning. In some embodiments, the spin fluid comprises (a) from about 5 to about 35 weight percent of a polymer, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the non-azeotropic composition comprising dichloromethane and 1 H,1 H,2H-heptafluorocyclopentane. In other embodiments, the spin fluid comprises (a) from about 6 to about 24 weight percent of a polymer, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the non-azeotropic composition comprising dichloromethane and 1H,1H,2H- heptafluorocyclopentane. In some embodiments, the spin fluid comprises from about 65 to about 95 weight percent of the spin agent, based on the total amount of the spin fluid, and in other embodiments from about 76 to about 94 weight percent of the 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 the spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 84 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, and in other embodiments from about 86 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 65 to about 80 weight percent of the spin agent, based on the total amount of the spin fluid.

[0057] In some embodiments, the spin agent comprises or consists essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[0058] The spin fluid may include additives, such as antioxidants or acid scavengers, minor amounts, provided that their presence does not interfere with the non-azeotropic nature of the compositions of dichloromethane and 1H,1 H,2H-heptafluorocyclopentane 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.

[0059] In some embodiments, the spin agent consists of about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[0060] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent of a polymer, based on the total amount of the spin fluid, and the spin agent consists essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane.

[0061] The spin agent can be used for a broad range of different polymers and blends / mixtures thereof. In some embodiments, the polymer is selected from polyolefins, fluoropolymers, and blends / mixtures thereof.

[0062] In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), polybutene- 1 , poly(4-methyl-1 -pentene), and blends / mixtures thereof. Particularly preferred polyolefins are polyethylene (PE), in particular high-density polyethylene (HDPE), and blends / mixtures of high- density polyethylene (HDPE) and low-density polyethylene (LDPE), in particular linear low-density polyethylene (LLDPE). In some embodiments, the polyolefin is a high-density polyethylene (HDPE).

[0063] 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 blend comprising polyethylene, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H-heptafluorocyclopentane. 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 polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane.

[0064] In some embodiments, the fluoropolymer is polyvinylidene fluoride.

[0065] In some embodiments, the spin fluid comprises about 20 to about 35 weight percent of a fluoropolymer, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0066] In some embodiments, the spin fluid comprises from about 6 to about 20 weight percent of polyolefin and from about 80 to about 94 weight percent of the spin agent. In another embodiment, the spin fluid comprises from about 20 to about 35 weight percent of fluoropolymer and from about 65 to about 80 weight percent of the spin agent.

[0067] In some embodiments, the spin fluid comprising the non-azeotropic composition as described herein exhibits a cloud point pressure in the range of about 45 to about 300 bar, in other embodiments in the range of about 50 to about 300 bar, and in other embodiments in the range of about 70 to about 300 bar. In some embodiments, the spin fluid comprising the non- azeotropic composition as described herein exhibits a cloud point pressure in the range of about 45 to about 250 bar, in other embodiments in the range of about 50 to about 250 bar, and in other embodiments in the range of about 70 to about 250 bar. In some embodiments, the spin fluid comprising the non-azeotropic composition as described herein exhibits a cloud point pressure in the range of about 45 to about 200 bar, in other embodiments in the range of about 50 to about 200 bar, and in other embodiments in the range 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 pressure becomes lower than the spin fluid’s bubble point pressure, premature and unwanted boiling occurs. 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.

[0068] When used as a spin agent, the homogeneous non-azeotropic compositions have the advantage that in the spin agent recovery process, upon condensation of the spin agent, no phase separation occurs. Furthermore, use of the non-azeotropic compositions described herein in spin fluids simplifies the separation of recovered spin agent such that its components can be recombined in any desired ratio.

[0069] Preparation of Plexifilamentary Fibrils of Polymer

[0070] In some embodiments, there is provided a process for the preparation of plexifilamentary fibrils of polymer. The process comprises the steps of:

[0071] (i) generating a spin fluid comprising (a) from about 5 to about 35 weight percent of a polymer, based on the total amount of the spin fluid, and

[0072] (b) a spin agent, and

[0073] (ii) flash spinning the spin fluid at a pressure that above the vapor pressure of the spin fluid into a region of essentially atmospheric pressure to form plexifilamentary fibrils of the polymer; wherein the spin agent comprises or consists essentially of a non-azeotropic composition comprising dichloromethane and 1H,1 H,2H-heptafluorocyclopentane.

[0074] In some embodiments, the flash-spinning is performed at a pressure in the range of about 45 to about 300 bar, in other embodiments in the range of about 50 to about 300 bar, or in other embodiments in the range of about 70 to about 300 bar. In some embodiments, the flash-spinning is performed at a pressure in the range of about 45 to about 250 bar, in other embodiments in the range of about 50 to about 250 bar, and in other embodiments in the range of about 70 to about 250 bar. In some embodiments, the flash-spinning is performed at a pressure in the range of about 45 to about 200 bar, in other embodiments in the range of about 50 to about 200 bar, and in other embodiments in the range of about 70 to about 200 bar. The region of lower pressure into which flash spinning occurs is usually at or around atmospheric pressure.

[0075] In some embodiments, the spin fluid comprises (a) from about 6 to about 24 weight percent of a polymer, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises or consists essentially of the non-azeotropic composition comprising dichloromethane and 1 H,1 H,2H-heptafluorocyclopentane.

[0076] In some embodiments, the spin fluid comprises from about 65 to about 95 weight percent of the spin agent, based on the total amount of the spin fluid, and in other embodiments from about 76 to about 94 weight percent of the 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 the spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 84 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, and in other embodiments from about 86 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 65 to about 80 weight percent of the spin agent, based on the total amount of the spin fluid.

[0077] In some embodiments, the spin agent comprises or consists essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[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 non-azeotropic nature of the compositions of dichloromethane and 1H,1 H,2H-heptafluorocyclopentane described herein. In some embodiments, the spin fluid comprises additives in an amount of about 1.0 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 agent consists of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane, in other embodiments from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane, in other embodiments from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1H,2H- heptafluorocyclopentane, and in other embodiments from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[0080] In some embodiments, the spin fluid comprises about 6 to about 24 weight percent of a polymer, based on the total amount of the spin fluid, and the spin agent consists essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane.

[0081] A broad range of different polymers and blends / mixtures thereof can be used in the process. In some embodiments, the polymer is selected from polyolefins, fluoropolymers, and blends / mixtures thereof.

[0082] In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), polybutene- 1 , poly(4-methyl-1 -pentene), and blends / mixtures thereof. Particularly preferred polyolefins are polyethylene (PE), in particular high-density polyethylene (HDPE), and blends / mixtures of high- density polyethylene (HDPE) and low-density polyethylene (LDPE), in particular linear low-density polyethylene (LLDPE). In some embodiments, the polyolefin is a high-density polyethylene (HDPE). 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 blend comprising polyethylene, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H-heptafluorocyclopentane. 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 polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane.

[0083] In some embodiments, the fluoropolymer is polyvinylidene fluoride.

[0084] In some embodiments, the spin fluid comprises about 20 to about 35 weight percent of a fluoropolymer, based on the total amount of the spin fluid, and a spin agent, wherein the spin agent consists essentially of from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0085] In some embodiments, the spin fluid comprises from about 6 to about 20 weight percent of polyolefin and from about 80 to about 94 weight percent of the spin agent In another embodiment, the spin fluid comprises from about 20 to about 35 weight percent of fluoropolymer and from about 65 to about 80 weight percent of the spin agent.

[0086] In some embodiments, there is provided plexifilamentary fibrils of polymer obtainable by the process described herein.

[0087] The shape of the assembly of plexifilamentary fibrils of polymer discharged from each spin orifice may be modified by any methods known in the art. In some embodiments, the plexifilamentary fibrils of polymer discharged from each spin orifice may be modified by passing into a shroud such as described on US 3,387,326, in other embodiments by passing into a slotted outlet such as described in US 3,467,744 or US 5,788,993, and in other embodiments 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. 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

[0088] Sheets comprising plexifilamentary fibrils of polymer can be formed by any method known in the art. In some embodiments, the stream of fibrils discharged from each spin orifice is directed towards a deflector device which alternately directs the stream of fibrils to the left and right onto a moving collecting device such that the fibrils accumulate in the form of a collected sheet of nonwoven flash-spun plexifilamentary fibrils, formed from fibrils oriented in an overlapping, multidirectional 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] In some embodiments, the bonded sheet is subjected to a mechanical softening process to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils. 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 phase behavior and flash spinning of polyethylene, polypropylene, and ethylene-butylene copolymer for non-azeotropic compositions. 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] Dichloromethane (DCM), CAS Nr. of 75-09-2 has an atmospheric boiling point of 39.6 °C and a molecular weight of 84.93 g / mol. The dichloromethane used had a purity level above 99.5 percent by weight.

[0099] 1 H,1 H,2H-heptafluorocyclopentane (HFCP, also known as 1 , 1 ,2, 2, 3,3,4- heptafluorocyclopentane), CAS Number 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.

[0100] All polymers used were dried during a minimum of 8 hours in a vacuum oven at about 45- 50 °C before use.

[0101] Spinning Equipment 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.

[0102] 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.

[0103] 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.

[0104] Results

[0105] Example 1 : Vapor liquid equilibrium for the composition of dichloromethane:

[0106] 1 H,1 H,2H-heptafluorocyclopentane

[0107] Figure 1 shows the calculated vapor liquid equilibrium for the mixture dichloromethane (DCM) and 1 H,1 H,2H-heptafluorocyclopentane (HFCP). This mixture does not form an azeotrope at any mixing ratio of the two components as illustrated by the difference between bubble point pressure and dew point pressure curves.

[0108] Example 2: Cloud point pressure study of polypropylene

[0109] Figure 2 shows the cloud point pressure curve of a spin fluid comprising 10 wt% of an isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 230 °C / 2.16 kg) and a melting temperature of 163 °C, and a spin agent of DCM and 1 H, 1 H,2H-heptafluorocyclopentane in a 45:55 ratio by weight. This spin fluid comprising 10 wt% isotactic polypropylene shows a cloud point pressure curve suitable for flash spinning. Example 3: Flash spinning performance of polypropylene

[0110] Flash spinning was performed on the equipment described above using a spin fluid comprising 10 wt% isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 230 °C / 2.16 kg) and melting temperature of 163 °C, and a spin agent of DCM and 1 H,1H,2H- heptafluorocyclopentane in a 45:55 ratio by weight at a spin temperature of about 210 °C and a spin pressure of about 78 bar.

[0111] Example 4: Flash spinning performance of polypropylene

[0112] Flash spinning was performed on the equipment described above using a spin fluid comprising 15 wt% isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 230 °C / 2.16 kg) and a melting peak temperature 163 °C, and a spin agent of DCM and 1 H,1 H,2H- heptafluorocyclopentane in a 45:55 ratio by weight at a spin temperature of about 200 °C and a spin pressure of about 57 bar.

[0113] Example 5: Cloud point pressure study of polypropylene

[0114] Figure 3 shows the cloud point pressure curve of a spin fluid comprising 15 wt% of an isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 210 °C / 2.16 kg) and a melting temperature 163 °C, and a spin agent of DCM and 1H,1 H,2H-heptafluorocyclopentane in a 40:60 ratio by weight. This spin fluid comprising 15 wt% isotactic polypropylene shows a cloud point pressure curve suitable for flash spinning.

[0115] Example 6: Flash spinning performance of polypropylene

[0116] Flash spinning was performed on the equipment described above using a spin fluid comprising 14 wt% isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 210 °C / 2.16 kg) and a melting temperature 163 °C, and a spin agent of DCM and 1H,1 H,2H- heptafluorocyclopentane in a 40:60 ratio by weight at a spin temperature of about 215 °C and a spin pressure of about 101 bar.

[0117] Example 7: Cloud point pressure study of polyethylene

[0118] Figure 4 shows the cloud point pressure curve of a spin fluid comprising 10 wt% of polyethylene with a density above 0.955 g / cm3(ISO 1183), and melt flow rate of 0.75 g / 10min (ISO 1133 190 °C / 2.16 kg), and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 72.5:27.5 ratio by weight. This spin fluid comprising 10 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0119] Example 8: Flash spinning performance of polyethylene

[0120] Flash spinning was performed on the equipment described above for a spin fluid comprising 10 wt% of polyethylene with a density above 0.955 g / cm3(ISO 1183), and melt flow rate of 0.75 g / 10min (ISO 1133 190 °C / 2.16 kg), and a spin agent of DOM and 1 H,1H,2H- heptafluorocyclopentane in a 72.5:27.5 ratio by weight at a spin temperature of about 192 °C and a spin pressure of about 73 bar.

[0121] Example 9: Flash spinning performance of polyethylene

[0122] Flash spinning was performed on the equipment described above using a spin fluid comprising 14 wt% of polyethylene with a density above 0.955 g / cm3(ISO 1183), and melt flow rate of 0.75 g / IOmin (ISO 1133 190 °C / 2.16 kg), and a spin agent of DOM and 1 H,1H,2H- heptafluorocyclopentane in a 72.5:27.5 ratio by weight at a spin temperature of about 210 °C and a spin pressure of about 87 bar.

[0123] Example 10: Cloud point pressure study of ethylene-butylene copolymer

[0124] Figure 5 shows the cloud point pressure curve of a spin fluid comprising 6 wt% of an ethylene-butylene copolymer having a density of 0.936 g / cm3(ISO 1183) and a melt flow index of 1.8 g / 10 min (ISO 1133, 190 °C / 2.16 kg / ), and a spin agent of DCM and 1H,1H,2H- heptafluorocyclopentane in a 75:25 ratio by weight. This spin fluid comprising 6 wt% ethylene- butylene copolymer shows a cloud point pressure curve suitable for flash spinning.

[0125] Example 11 : Flash spinning performance of ethylene-butylene copolymer

[0126] Flash spinning was performed on the equipment described above using a spin fluid comprising 6 wt% ethylene-butylene copolymer having a density of 0.936 g / cm3(ISO 1183) and a melt flow index of 1.8 g / 10 min (ISO 1133, 190 °C / 2.16 kg), and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 75:25 ratio by weight at a spin temperature of about 195 °C and a spin pressure of about 75 bar. Example 12: Cloud point pressure study of ethylene-butylene copolymer

[0127] Figure 5 shows the cloud point pressure curve of a spin fluid comprising 17 wt% of an ethylene-butylene copolymer having a density of 0.936 g / cm3(ISO 1183) and a melt flow index of 1.8 g / 10 min (ISO 1133, 190 °C / 2.16 kg), and a spin agent of DCM and 1 H,1H,2H- heptafluorocyclopentane in a 75:25 ratio by weight. This spin fluid comprising 6 wt% ethylene- butylene copolymer shows a cloud point pressure curve suitable for flash spinning.

[0128] Example 13: Flash spinning performance of ethylene-butylene copolymer

[0129] Flash spinning was performed on the equipment described above using a spin fluid comprising 17 wt% ethylene-butylene copolymer having a density of 0.936 g / cm3(ISO 1183) and a melt flow index of 1.8 g / 10 min (ISO 1133, 190 °C / 2.16 kg), and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 75:25 ratio by weight at a spin temperature of about 210 °C and a spin pressure of about 63 bar.

[0130] Example 14: Flash spinning performance of polyethylene / polypropylene blend

[0131] Flash spinning was performed on the equipment described above using a spin fluid comprising 10 wt% of a polymer blend of a polyethylene with a density above 0.951 g / cm3(ISO 1183), and a melt flow rate of 0.08 g / 10 min (ISO 1133, 190 °C / 2.16kg) and of 8.4 g / 10min (ISO 1133 190 °C / 21.6 kg), and an isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 230 °C / 2.16 kg) and a melting temperature of 163 °C, in a 80:20 ratio by weight, and a spin agent of DCM and 1H,1 H,2H-heptafluorocyclopentane in a 75:25 ratio by weight at a spin temperature of about 205 °C and a spin pressure of about 95 bar.

[0132] Example 15: Flash spinning performance of polyethylene / polypropylene blend

[0133] Flash spinning was performed on the equipment described above using a spin fluid comprising 16 wt% of a polymer blend of a polyethylene with a density above 0.951 g / cm3(ISO 1183), and a melt flow rate of 0.08 g / 10 min (ISO 1133, 190 °C / 2.16kg) and of 8.4 g / 10min (ISO 1133 190 °C / 21.6 kg), and an isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 230 °C / 2.16 kg) and a melting temperature of 163 °C, in a 60:40 ratio by weight, and a spin agent of DCM and 1H,1 H,2H-heptafluorocyclopentane in a 70:30 ratio by weight at a spin temperature of about 215 °C and a spin pressure of about 109 bar. Example 16: Flash spinning performance of polyethylene / polypropylene blend

[0134] Flash spinning was performed on the equipment described above using a spin fluid comprising 16 wt% of a polymer blend of a polyethylene with a density above 0.951 g / cm3(ISO 1183), and a melt flow rate of 0.08 g / 10 min (ISO 1133, 190 °C / 2.16kg) and of 8.4 g / 10min (ISO 1133 190 °C / 21.6 kg), and an isotactic polypropylene with a melt flow rate of 4.5 g / 10min (ISO 1133, 230 °C / 2.16 kg) and a melting temperature of 163°C, in a 80:20 ratio by weight, and a spin agent of DCM and 1H,1 H,2H-heptafluorocyclopentane in a 75:25 ratio by weight at a spin temperature of about 214 °C and a spin pressure of about 79 bar.

[0135] Example 17: Cloud point pressure study of polyvinylidene fluoride

[0136] Figure 7 shows the cloud point pressure curve of a spin fluid comprising 26 wt% of polyvinylidene fluoride and a spin agent of DCM and 1 H,1 H,2H-heptafluorocyclopentane in a 55:45 ratio by weight. This spin fluid comprising 26 wt% polyvinylidene fluoride (Kynar® 740 with a specific gravity of 1.77-1.79 g / cm3(ASTM D792, 23 °C), melting point of 165-172 °C, and melt flow rate of 1.5-3.0 g / 10 min (ASTM D1238, 232 °C, 3.8 kg load) shows a cloud point pressure curve suitable for flash spinning.

[0137] Example 18: Flash spinning performance of polyvinylidene fluoride

[0138] Flash spinning was performed on the equipment described above using a spin fluid comprising 22 wt% of polyvinylidene fluoride (Kynar® 740 with a specific gravity of 1.77-1.79 g / cm3(ASTM D792, 23 °C), melting point of 165-172 °C, and melt flow rate of 1.5-3.0 g / 10 min (ASTM D1238, 232 °C, 3.8 kg load), and a spin agent of DCM and 1 H,1H,2H-heptafluorocyclopentane in a 60:40 ratio by weight at a spin temperature of about 226 °C and a spin pressure of about 73 bar.

[0139] Table 1: Summary of the flash spinning experiments of Examples 3, 4, 6, 8, 9, 11,

[0140] 13, 14, 15, 16, and 18.

[0141] *(1)1 H, 1 H,2H-heptafluorocyclopentane

[0142] *(2)calculated based on the IPCC 2021 report (global warming potential over a 100-year period)

[0143] *<3> ethylene-butylene copolymer

[0144] The non-azeotropic compositions exhibit a desirably low GWP value of below 250. This makes these compositions suitable as replacements for currently used spin agents.

[0145] In addition, the above examples illustrate that the non-azeotropic compositions can be used as a spin agent for the flash spinning process of a range of polymers for different polymer concentrations, spin temperatures, and spin pressures. This allows an efficient preparation of plexifilamentary fibrils.

[0146] OTHER EMBODIMENTS

[0147] 1. In some embodiments, the present application provides a non-azeotropic composition comprising dichloromethane and 1H,1 H,2H-heptafluorocyclopentane.

[0148] 2. The non-azeotropic composition of embodiment 1 comprising from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane.

[0149] 3. The non-azeotropic composition of any one of embodiments 1 or 2 comprising from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane. 4. The non-azeotropic composition of any one of embodiments 1 or 2 comprising from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane.

[0150] 5. The non-azeotropic composition of any one of embodiments 1 or 2 comprising from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H , 1 H ,2H-heptafluorocyclopentane.

[0151] 5. The non-azeotropic composition of any of the preceding embodiments consisting essentially of or consisting of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0152] 6. The non-azeotropic composition of any of the preceding embodiments consisting essentially of or consisting of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0153] 7. The non-azeotropic composition of any of the preceding embodiments consisting essentially of or consisting of from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0154] 8. The non-azeotropic composition of any one of the preceding embodiments consisting essentially of or consisting of from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0155] 9. In some embodiments, the present application provides a spin fluid for flash spinning comprising

[0156] (a) from about 5 to about 35 weight percent weight percent of a polymer, based on the total amount of the spin fluid, and

[0157] (b) a spin agent, wherein the spin agent comprises a non-azeotropic composition comprising dichloromethane and 1H,1 H,2H-heptafluorocyclopentane.

[0158] 10. The spin fluid of embodiment 8 comprising from about 6 to about 24 weight percent of a polymer. 11. The spin fluid of embodiment 9 or 10 comprising from about 65 to about 95 weight percent, or from about 76 to about 94 weight percent of the spin agent.

[0159] 12. The spin fluid of any of the preceding embodiments 9 to 11 , wherein the polymer is selected from polyolefins, fluoropolymers, and blends / mixtures thereof.

[0160] 13. The spin fluid of embodiment 12, wherein the polyolefins are selected from the group consisting of polyethylene, polypropylene, polybutene-1, poly(4-methyl-1-pentene), and blends / mixtures thereof.

[0161] 14. The spin fluid of embodiment 12 or 13, wherein the polyolefins are selected from the group consisting of polyethylene (PE), polypropylene (PP), and blends / mixtures thereof.

[0162] 15. The spin fluid of any of embodiments 12 to 14, wherein the polyethylene is a high-density polyethylene (HDPE), a blend of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE), or a blend of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE).

[0163] 16. The spin fluid of any of embodiments 12 to 15, wherein the fluoropolymer is polyvinylidene fluoride.

[0164] 17. The spin fluid of any of embodiments 9 to 16, wherein the spin agent additionally comprises an additive, selected from antioxidants, acid scavengers, and blends thereof.

[0165] 18. The spin fluid of any of embodiments 9 to 17, wherein the spin agent comprises a non- azeotropic composition consisting essentially or consisting of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane.

[0166] 19. The spin fluid of embodiment 18, wherein the non-azeotropic composition consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane. 20. The spin fluid of embodiment 18 or 19, wherein the non-azeotropic composition consists essentially of or consists of from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0167] 21. The spin fluid of any one of embodiments 18 to 20, wherein the non-azeotropic composition consists essentially of or consists of from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1H,2H- heptafluorocyclopentane.

[0168] 22. In some embodiments, the present application provides a process for the preparation of plexifilamentary fibrils of polymer which comprises the steps of:

[0169] (i) generating a spin fluid comprising

[0170] (a) from about 5 to about 35 weight percent of a polymer, based on the total amount of the spin fluid, and

[0171] (b) a spin agent, and

[0172] (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 polymer, wherein the spin agent comprises a non-azeotropic composition of dichloromethane and 1 H,1H,2H- heptafluorocyclopentane.

[0173] 23. The process of embodiment 22, wherein the spin fluid comprises from about 6 to about 24 weight percent of a polymer, based on the total amount of the spin fluid.

[0174] 24. The process of embodiment 22 or 23, wherein the spin fluid comprises from about 65 to about 95 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid.

[0175] 25. The process of any of embodiments 22 to 24, wherein the polymer is selected from polyolefins, fluoropolymers, and blends / mixtures thereof.

[0176] 26. The process of embodiment 25, wherein the polyolefins are selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1-pentene), and blends / mixtures thereof. 27. The process of embodiment 25 or 26, wherein the polyolefins are selected from the group consisting of polyethylene (PE), polypropylene (PP), and blends / mixtures thereof.

[0177] 28. The process of any of embodiments 25 to 27, wherein the polyethylene is a high-density polyethylene (HDPE), a blend of a high-density polyethylene (HDPE) with a low-density polyethylene (LDPE), or a blend of a high-density polyethylene (HDPE) with a linear low-density polyethylene (LLDPE).

[0178] 29. The process of any of embodiments 25 to 28, wherein the fluoropolymer is polyvinylidene fluoride.

[0179] 30. The process of any of embodiments 22 to 29, wherein the spin agent additionally comprises an additive, selected from antioxidants, acid scavengers, and blends thereof.

[0180] 31. The process of any of embodiments 22 to 30, wherein the spin agent comprises a non- azeotropic composition consisting essentially or consisting of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane,

[0181] 32. The process of embodiment 31, wherein the non-azeotropic composition consists essentially of or consists of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0182] 33. The process of embodiment 31 or 32, wherein the non-azeotropic composition consists essentially of or consists of from about 35 to about 55 weight percent dichloromethane and from about 65 to about 45 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0183] 34. The process of any one of embodiments 31 to 33, wherein the non-azeotropic composition consists essentially of or consists of from about 40 to about 80 weight percent dichloromethane and from about 60 to about 20 weight percent 1 H,1 H,2H-heptafluorocyclopentane.

[0184] 35. In some embodiments, the present application provides a use of the spin fluid of any of embodiments 9 to 21 for preparing of plexifilamentary fibrils of polymer by flash spinning. 36. The plexifilamentary fibrils of polymer obtainable by the process of any one of embodiments 22 to 34.

[0185] 37. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polymer of embodiment 36.

[0186] 38. The sheet of embodiment 37, wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

[0187] 39. A bonded sheet obtainable by thermally or mechanically bonding the consolidated sheet of embodiment 38.

[0188] 40. A softened sheet obtainable by softening the consolidated sheet of embodiment 35 or by softening the bonded sheet of embodiment 39.

[0189] 41. A multilayer sheet comprising two or more sheets wherein at least one sheet is a sheet according to any one of embodiments 37 to 40.

[0190] 42. An article comprising plexifilamentary fibrils of polymer of embodiment 36 and / or a sheet of any one of embodiments 37 to 40 and / or a multilayer sheet of embodiment 41.

[0191] 43. The article of embodiment 42 which is selected from garments, protective apparel, packaging materials, house wrap, roof lining, car covers, medical and non-medical packaging, filtration media, print media, tags and labels, and accessories.

[0192] 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. 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 non-azeotropic composition comprising from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane.

2. A spin fluid for flash spinning comprising(a) from about 5 to about 35 weight percent of a polymer, based on the total amount of the spin fluid, and(b) a spin agent, wherein the spin agent comprises a non-azeotropic composition comprising dichloromethane and 1H,1 H,2H-heptafluorocyclopentane.

3. The spin fluid of claim 2 comprising from about 65 to about 95 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 65 to about 80 weight percent of the spin agent, based on the total amount of the spin fluid.

4. The spin fluid of claims 2 or 3, wherein the polymer is selected from the group consisting of polyolefins, fluoropolymers, and blends / mixtures thereof, or selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1-pentene), polyvinylidene fluoride, and blends / mixtures thereof.

5. The spin fluid of any one of claims 2 to 4, wherein the spin agent additionally comprises an additive, selected from antioxidants, acid scavengers, and blends thereof.

6. The spin fluid of any one of claims 2 to 5, wherein the spin agent comprises a non-azeotropic composition comprising or consisting essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane.

7. The spin fluid of any one of claims 2 to 6, wherein the spin agent comprises a non-azeotropic composition comprising or consisting essentially of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1H,1 H,2H- heptafluorocyclopentane.

8. A process for the preparation of plexifilamentary fibrils of polymer which comprises the steps of:(i) generating a spin fluid comprising(a) from about 5 to about 35 weight percent of a polymer, 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 polymer, wherein the spin agent comprises a non-azeotropic composition of dichloromethane and 1 H,1H,2H- heptafluorocyclopentane.

9. The process of claim 8, wherein the spin fluid comprises from about 65 to about 95 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 76 to about 94 weight percent of the spin agent, based on the total amount of the spin fluid, or from about 65 to about 80 weight percent of the spin agent, based on the total amount of the spin fluid.

10. The process of claims 8 or 9, wherein the polymer is selected from the group consisting of polyolefins, fluoropolymers, and blends / mixtures thereof, or selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1-pentene), polyvinylidene fluoride, and blends / mixtures thereof.

11. The process of any one of claims 8 to 10 wherein the spin agent comprises a non- azeotropic composition consisting essentially of from about 35 to about 85 weight percent dichloromethane and from about 65 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane.

12. The process of any one of claims 8 to 11 wherein the spin agent comprises a non- azeotropic composition consisting essentially of from about 70 to about 85 weight percent dichloromethane and from about 30 to about 15 weight percent 1 H,1H,2H- heptafluorocyclopentane.

13. Use of the spin fluid of any one of claims 2 to 7 for preparing of plexifilamentary fibrils of polymer by flash spinning.

14. A plexifilamentary film-fibril strand of polymer obtainable by the process of any one of claims 8 to 12.

15. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polymer of claim 14.

16. The sheet of claim 15, wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

17. An article comprising the plexifilamentary fibrils of polymer of claim 14 and / or the sheet of claim 15 or 16.

18. The article of claim 17 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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