Improved flash spinning process for polyolefins using flash spinning agents comprising a monofluorohydrocarbon with 4 or 5 carbon atoms

Abstract

The present invention relates to (i) a spin fluid for flash spinning comprising (a) at least one polyolefin, and (b) a spin agent comprising at least one monofluorohydrocarbon with 4 to 5 carbon atoms, and (ii) a process for the preparation of plexifilamentary fibrils of polyolefins using the spin fluid.

Description

[0001] TITLE

[0002] IMPROVED FLASH SPINNING PROCESS FOR POLYOLEFINS USING FLASH SPINNING AGENTS COMPRISING A MONOFLUOROHYDROCARBON WITH 4

[0003] OR 5 CARBON ATOMS

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to (i) a spin fluid for flash spinning comprising (a) at least one polyolefin, and (b) a spin agent comprising at least one monofluorohydrocarbon with 4 or 5 carbon atoms, and (ii) a process for the preparation of plexifilamentary fibrils of polyolefins using the spin fluid.

[0006] BACKGROUND

[0007] 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.

[0008] 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 to single component spin agents, i.e., when spin agents comprise only one solvent but not to multi-component spin agents. Therefore, in some instances, it is advantageous if spin agents comprise only one solvent. However, using single component spin agents sometimes results in undesirably high cloud point pressures which may require the use of high pressure-resistant equipment leading to increased equipment and operating costs. Thus, there is a need to find suitable single component spin agents that provide suitable cloud point pressures for flash spinning polymers. On the other hand, in some instances, it is advantageous to use spin agents comprising two or more solvents to provide a broader range of solvent properties, e.g., to allow greater flexibility with respect to the cloud point pressure, for flash spinning different polymers at different desired spin temperatures and spin pressures.

[0009] Furthermore, in view of the growing concerns regarding climate change and increasing regulatory requirements, there is a need to find suitable low GWP spin agent compositions.

[0010] US 3,227,794 and US 5,081 ,177 describe flash spinning of polyethylene using hydrochlorofluorocarbons (HCFCs) as single component spin agents. The disadvantage of such HCFCs is that they usually have a high ozone depletion potential (ODP) and a high global warming potential (GWP). This is undesirable in view of the growing concerns regarding ozone depletion and climate change and increasing regulatory requirements.

[0011] US 5,250,237 describes flash spinning of polyethylene and polypropylene using alcohols as single component spin agents. The alcohols used have boiling points above 70°C which has the disadvantage that the spin cell needs to be heated to prevent condensation of the spin agent in the spin cell. This leads to increased equipment and operating costs. In addition, when using these alcohols, the cloud point pressure exceeds 200 bar which requires the use of high pressure-resistant equipment.

[0012] US 4,1 12,029 describes flash spinning of polyolefins using pentanes, such as n- pentane, isopentane or neopentane, as single component spin agents or using mixtures of pentanes, such as mixtures of n-pentane and isopentane as multi-component spin agents. US 5,147,586 suggests spin agent compositions comprising either n-pentane alone or n-pentane in combination with methanol. US 6,004,672 discloses flash spinning of mixtures of polyethylene and polypropylene using n-pentane as single component spin agents or using mixtures of n-pentane and cyclopentane as multi-component spin agents. However, flash spinning of polyethylene using pentane as a single component spin agent results in an undesirably high cloud point pressure. A reduction in the cloud point pressure is advantageous as it reduces the maximum operating pressure of a flash spinning facility.

[0013] WO 2016 / 200873 A1 suggests multi-component spin agent compositions comprising dichloromethane or 1 ,2-dichloroethylene in combination with 1 H,6H-perfluorohexane, 1 H- perfluorohexane, or 1 H-perfluoroheptane. However, the use of such linear highly fluorinated hydrofluorocarbons in combination with DCM or DOE results in spin agents that often exhibit undesirably high global warming potential (GWP). US 7,179,413 B1 describes flash spinning of synthetic polymers using multicomponent spin agents consisting of a primary spin agent selected from C4-C7 hydrocarbons, chlorinated compounds, fluorinated compounds, and brominated compounds, and a co-spin agent which is a fluorinated compound containing 4 to 8 carbon atoms and a double bond, and having a boiling point below 100 °C. The presence of highly fluorinated compounds in these mixtures may still result in an undesirably high global warming potential (GWP).

[0014] Accordingly, there is a need for, and the present inventors have discovered, low GWP compositions comprising at least one monofluorohydrocarbon that provide suitable cloud point pressures for flash spinning polyolefins.

[0015] SUMMARY OF THE INVENTION

[0016] In one embodiment, the invention is directed to a spin fluid for flash spinning comprising (a) from about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

[0017] In a further embodiment, the invention is directed to a process for the preparation of plexifilamentary fibrils of polyolefin. The process comprises the steps of:

[0018] (i) generating a spin fluid comprising

[0019] (a) about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and

[0020] (b) a spin agent, and

[0021] (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 polyolefin, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

[0022] BRIEF DESCRIPTION OF THE FIGURES

[0023] Fig. 1 shows the cloud point pressure curves of a spin fluid comprising 15 wt% polyethylene (PE) and a spin agent of n-pentane (comparative example 1), of a spin fluid comprising 15 wt% polyethylene (PE) and a spin agent of n-pentane and perfluorohexane in a 90:10 ratio by weight (comparative example 2), and of a spin fluid comprising 15 wt% polyethylene (PE) and a spin agent of 1 -fluoropentane (example 1). Fig. 2 shows the cloud point pressure curves of a spin fluid comprising 13 wt% polypropylene (PP) and a spin agent of 1 -fluorobutane (example 2), and of a spin fluid comprising 12 wt% polypropylene (PP) and a spin agent of n-butane (comparative example 3).

[0024] Fig. 3 shows the cloud point pressure curves of a spin fluid comprising 24 wt% polyethylene (PE) and a spin agent of 1 -fluoropentane and n-pentane in a 50:50 ratio by weight (example 3), of a spin fluid comprising 18 wt% polyethylene (PE) and a spin agent of 1 -fluoropentane, n-pentane and cyclopentane in a 50:30:20 ratio by weight (example 4).

[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.

[0028] Density is determined according to the method described in ISO 1 183 (Plastics - Methods for determining the density of non-cellular plastics).

[0029] Melting point is determined by differential scanning calorimetry, following the guidance provided in ASTM D3418 (Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry) and ASTM Standard F2625 (Standard Test Method for Measurement of Enthalpy of Fusion, Percent Crystallinity and Melting Point of Ultra-High-Molecular weight polyethylene by means of differential scanning calorimetry). For polyethylene, heating and cooling is performed under inert gas at a rate of 10 °C / minute, heating the sample first from room temperature to 210 °C, then cooling the sample back to room temperature and subsequently heating the sample a second time to 210 °C. The melting point reported herein is the peak temperature of the endotherm of the second heating cycle. For polypropylene, the same procedure applies - where the maximum temperature is 230 °C.

[0030] The melt flow rate is determined according to the method described in ISO 1 133 (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) 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 (2.16kg).

[0031] 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.

[0032] 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 in the range of 0.94 to 0.98 grams per cubic centimeter (ISO 1133), 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. The polyethylene may contain up to about 10 weight percent or up to about 5 weight percent of other polymers, such as other polyolefins, for example polypropylene.

[0033] The term “polypropylene” is intended to embrace not only homopolymers of propylene but also copolymers and terpolymers where at least 85% of the recurring units are propylene units. Furthermore, unless otherwise specifically limited, the term “polypropylene” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries. The polypropylene may contain up to about 10 weight percent or up to about 5 weight percent of other polymers, such as other polyolefins, for example polyethylene.

[0034] The term “polymer type” refers to the chemical class into which the polymer falls, for example, polyolefin, polyethylene, polypropylene, etc.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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. The term “bubble point pressure” refers to the pressure at which, at constant temperature, a liquid, liquid mixture, or liquid-solution begins to boil.

[0039] 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.

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

[0041] The term “normal boiling point” refers to the temperature that is reached when the liquid vapor pressure equals 101.325 kPa (1 atm).

[0042] 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.

[0043] Spin Agents and Spin Fluids for Flash Spinning

[0044] Provided herein are spin fluids for flash spinning polyolefins. The spin fluid comprises (a) from about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

[0045] In some embodiments, the spin fluid comprises (a) from about 8 to about 25 weight percent of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of, or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 12 to about 22 weight percent, or from about 14 to about 20 weight percent, of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 12 to about 18 weight percent of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 18 to about 22 weight percent, of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms.

[0046] In some embodiments, the spin fluid comprises (a) from about 10 to about 25 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1- pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 10 to about 20 weight percent, or from about 10 to about 15 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms.

[0047] In some embodiments, the spin fluid comprises from about 75 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 78 to about 88 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 86 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 82 to about 88 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 78 to about 82 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 75 to about 90 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 90 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 85 to about 90 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 85 weight percent of the spin agent, based on the total amount of the spin fluid.

[0048] In some embodiments, the at least one monofluorohydrocarbon with 4 or 5 carbon atoms is selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane, and mixtures thereof.

[0049] In some embodiments, the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof.

[0050] In some embodiments, the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane and mixtures thereof. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluorobutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylpropane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylpropane.

[0051] In some embodiments, the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2-dimethyl- propane, and mixtures thereof. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoropentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 3-fluoropentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-3- methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoro-3-methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-2,2-dimethylpropane.

[0052] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms.

[0053] In some embodiments, the at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms is selected from the group consisting of n- pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

[0054] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

[0055] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 carbon atoms is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0056] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof.

[0057] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane, 2-methylpentane, 3-methylpentane, 2,2- dimethylbutane, 2,3-dimethylbutane, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent.

[0058] In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 50 to about 90 weight percent of at least one monofluorohydrocarbon with 4 or 5 carbon atoms, selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and from about 70 to more than about 0 weight percent, or from about 50 to about 10 weight percent of at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2- methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2- butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0059] In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane and n-pentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 40 to about 90 weight percent, or from about 50 to about 70 weight percent of 1- fluoropentane, and from about 70 to more than about 0 weight percent, or from about 60 to about 10 weight percent, or from about 50 to about 30 weight percent of n-pentane.

[0060] In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, n-pentane and cyclopentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1- fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of n-pentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane. In some embodiments, the amount of 1 -fluorobutane, n- pentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0061] In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, 2-methylpentane and cyclopentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1- fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of 2-methylpentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane. In some embodiments, the amount of 1 -fluorobutane, 2-methylpentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0062] The spin fluid may include additives, such as antioxidants or acid scavengers, in minor amounts. In some embodiments, the spin fluid comprises additives in an amount of about 1 .5 weight percent or less of the total amount of the spin agent, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin agent.

[0063] The spin agent can be used for a broad range of different polyolefins and blends / mixtures thereof.

[0064] In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), polybutene-1 (PB-1), poly(4-methyl-1 -pentene) (P4M1 P), and blends or mixtures thereof. In other embodiments, the polyolefins are blends comprising polyethylene, blends comprising polypropylene, blends comprising polybutene-1 , or blends comprising poly(4-methyl-1- pentene). 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).

[0065] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof.

[0066] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1- fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3- methylbutane, 1-fluoro-2,2-dimethylpropane, and mixtures thereof.

[0067] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0068] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0069] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof.

[0070] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane and mixtures thereof.

[0071] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof. In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane, 2-methylpentane, 3-methylpentane, 2,2- dimethylbutane, 2,3-dimethylbutane, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent.

[0072] In some embodiments, the spin fluid comprising the 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 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 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 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. Properties of the spin fluids comprising the spin agent compositions

[0073] The compounds 1 -fluorobutane and 2-fluorobutane have reported GWP-100 values of 1 (J. B. Burkholder et al. J. Phys. Chem. A 2020, 124, 4793-4800). No calculated GWP values are available for 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro- 2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane. However, these compounds are expected to have short atmospheric lifetimes due to their relatively high reactivity, so a very low GWP-100 of about 1 or less may be assumed. While no specific data is available for hydrocarbons, such as n-pentane and cyclopentane, values reported for hydrocarbons with up to four carbon atoms show a rapid decline in GWP-100 as the number of carbon atoms increases, so it is reasonable to assume a GWP-100 at or close to zero for these compounds.

[0074] Accordingly, the spin agent compositions disclosed herein consisting of 1 -fluorobutane or 1 -fluoropentane, or combining 1 -fluorobutane or 1 -fluoropentane and one or more hydrocarbons with 5 or 6 carbon atoms have a GWP-100 of about 1 or less.

[0075] Preparation of Plexifilamentary Fibrils of Polyolefin

[0076] In some embodiments, there is provided a process for the preparation of plexifilamentary fibrils of polyolefin. The process comprises the steps of:

[0077] (i) generating a spin fluid comprising

[0078] (a) about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and

[0079] (b) a spin agent, and

[0080] (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 polyolefin, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

[0081] In some embodiments, the flash-spinning is performed at a pressure of about 45 to about 300 bar, in other embodiments of about 50 to about 300 bar, or in other embodiments 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 flashspinning 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.

[0082] In some embodiments, the spin fluid comprises (a) from about 8 to about 25 weight percent of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 12 to about 22 weight percent, or from about 14 to about 20 weight percent, of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 12 to about 18 weight percent of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 18 to about 22 weight percent, of a polyethylene, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms.

[0083] In some embodiments, the spin fluid comprises (a) from about 10 to about 25 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1- pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 10 to about 20 weight percent, or from about 10 to about 15 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms. In other embodiments, the spin fluid comprises (a) from about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises, consists essentially of or consists of a monofluorohydrocarbon with 4 or 5 carbon atoms.

[0084] In some embodiments, the spin fluid comprises from about 75 to about 92 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 78 to about 88 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 86 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 82 to about 88 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 78 to about 82 weight percent of the spin agent, based on the total amount of the spin fluid. In some embodiments, the spin fluid comprises from about 75 to about 90 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 80 to about 90 weight percent of the spin agent, based on the total amount of the spin fluid, in other embodiments from about 85 to about 90 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 85 weight percent of the spin agent, based on the total amount of the spin fluid.

[0085] In some embodiments, the at least one monofluorohydrocarbon with 4 or 5 carbon atoms is selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane, and mixtures thereof.

[0086] In some embodiments, the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof.

[0087] In some embodiments, the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane and mixtures thereof. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluorobutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylpropane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylpropane.

[0088] In some embodiments, the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2-dimethyl- propane, and mixtures thereof. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoropentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 3-fluoropentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-3- methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 2-fluoro-3-methylbutane. In some embodiments, the spin agent comprises, consists essentially of, or consists of 1-fluoro-2,2-dimethylpropane.

[0089] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms.

[0090] In some embodiments, the at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms is selected from the group consisting of n- pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

[0091] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

[0092] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 carbon atoms is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0093] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof.

[0094] In some embodiments, the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane, 2-methylpentane, 3-methylpentane, 2,2- dimethylbutane, 2,3-dimethylbutane, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent.

[0095] In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 50 to about 90 weight percent of at least one monofluorohydrocarbon with 4 or 5 carbon atoms, selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2- methylpropane, 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and from about 70 to more than about 0 weight percent, or from about 50 to about 10 weight percent of at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2- methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2- butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0096] In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane and n-pentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 40 to about 90 weight percent, or from about 50 to about 70 weight percent of 1- fluoropentane, and from about 70 to more than about 0 weight percent, or from about 60 to about 10 weight percent, or from about 50 to about 30 weight percent of n-pentane.

[0097] In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, n-pentane and cyclopentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1- fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of n-pentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane. In some embodiments, the amount of 1 -fluorobutane, n- pentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0098] In some embodiments, the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, 2-methylpentane and cyclopentane. In some embodiments, the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1- fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of 2-methylpentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane. In some embodiments, the amount of 1 -fluorobutane, 2-methylpentane and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0099] The spin fluid may include additives, such as antioxidants or acid scavengers, in minor amounts. In some embodiments, the spin fluid comprises additives in an amount of about 1 .5 weight percent or less of the total amount of the spin agent, and in other embodiments in an amount of about 0.1 weight percent or less of the total amount of the spin agent. The spin agent can be used for a broad range of different polyolefins and blends / mixtures thereof.

[0100] In some embodiments, polyolefins are polyethylene (PE), polypropylene (PP), polybutene-1 (PB-1), poly(4-methyl-1 -pentene) (P4M1 P), and blends or mixtures thereof. In other embodiments, the polyolefins are blends comprising polyethylene, blends comprising polypropylene, blends comprising polybutene-1 , or blends comprising poly(4-methyl-1- pentene). 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).

[0101] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof.

[0102] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1- fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3- methylbutane, 1-fluoro-2,2-dimethylpropane, and mixtures thereof.

[0103] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0104] In some embodiments, the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0105] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof.

[0106] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane and mixtures thereof.

[0107] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof.

[0108] In some embodiments, the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1-pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane, 2-methylpentane, 3-methylpentane, 2,2- dimethylbutane, 2,3-dimethylbutane, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent.

[0109] In some embodiments, there is provided plexifilamentary fibrils of polyolefin obtainable by the process described herein. The shape of the assembly of plexifilamentary fibrils of polyolefin discharged from each spin orifice may be modified by any methods known in the art. In some embodiments, the plexifilamentary fibrils of polyolefin 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 8,1 14,325. In some embodiments, streams of fibrils from multiple orifices may exit via a common slot as described in US 3,564,088.

[0110] 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

[0111] Sheets comprising plexifilamentary fibrils of polyolefin 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 ,01 1 , US 5,750,152 and WO92 / 2051 1. 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 .

[0112] 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.

[0113] 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. 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.

[0114] In some embodiments, the bonded sheet is subjected to a mechanical softening process to obtain a softened sheet of nonwoven flash-spun plexifilamentary fibrils.

[0115] 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.

[0116] 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.

[0117] 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. The uniform appearance and opaqueness of such sheet of nonwoven flash-spun plexifilamentary fibrils is particularly suitable for printing.

[0118] EXAMPLES

[0119] A study has been performed for the phase behavior and flash spinning of polyethylene and polypropylene for different 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.

[0120] Materials Used

[0121] 1-Fluorobutane, CAS Nr. 2366-52-1 has an atmospheric boiling temperature of 32 to 33°C and a molecular weight of 76.1 1 g / mol. The 1 -fluorobutane used had a purity above 97 percent by weight.

[0122] 1-Fluoropentane, CAS Nr. 592-50-7 has an atmospheric boiling temperature of 62 to 63°C and a molecular weight of 90.14 g / mol. The 1 -fluoropentane used had a purity above 98 percent by weight. N-pentane, CAS No. 109-66-0, has an atmospheric boiling point of 36 °C and a molecular weight of 72.15 g / mol. The n-pentane used had a purity level above 99 percent by weight.

[0123] N-butane, CAS No. 106-97-8 has an atmospheric boiling point of -1 °C and a molecular weight of 58.12 g / mol. The n-butane used had a purity level above 99 per cent by weight.

[0124] Cyclopentane, CAS No. 287-92-3, has an atmospheric boiling point of 49°C and a molecular weight of 70.1 g / mol. The cyclopentane used had a purity level above 97 percent by weight.

[0125] 2-Methylbutane (isopentane), CAS No. 78-78-4, has an atmospheric boiling point of 30 °C and a molecular weight of 72.15 g / mol. The 2-methylbutane used had a purity level above 97 percent by weight.

[0126] Perfluorohexane, also known as tetradecafluorohexane, CAS Nr. 355-42-0 has an atmospheric boiling temperature of 58 to 60 °C and a molecular weight of 338.04 g / mol. The perfluorohexane used had a purity level above 97 percent by weight.

[0127] Three different polyethylenes were used:

[0128] Polyethylene A was a polyethylene having a density of 0.96 g / cm3(ISO 1 183), a melting point of 136°C, and melt flow rate of 0.9 g / 10min (ISO 1 133, 190 °C / 2.16 kg).

[0129] Polyethylene B was a polyethylene having a density of 0.952 g / cm3(ISO 1183), a melting point of 135°C, and melt flow rate of 2.1 g / 10min (ISO 1 133, 190 °C / 21 .6 kg).

[0130] Polyethylene C 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 1.2 g / 10min (ISO 1 133, 190 °C / 2.16 kg).

[0131] Two different polypropylenes were used:

[0132] Polypropylene A was an isotactic polypropylene having a melt flow rate of 4.5 g / 10 min (ISO 1 133, 230 “C / 2.16 kg).

[0133] Polypropylene B was an isotactic polypropylene having a melt flow rate of 0.9 g / 10 min (ISO 1 133, 230 “C / 2.16 kg).

[0134] All polymers used were dried during a minimum of 8 hours in a vacuum oven at about 45-50 °C before use.

[0135] Spinning Equipment

[0136] 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 0.020 inch (0.508 mm) and a length of 0.020 inch (0.508 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.

[0137] 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.

[0138] 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

[0139] T1 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.

[0140] Results

[0141] Comparative Examples 1 and 2 and Example 1 : Cloud point pressure study of polyethylene

[0142] Figure 1 shows the cloud point pressure curve of a spin fluid comprising 15 wt% polyethylene A and a spin agent of n-pentane (comparative example 1).

[0143] Figure 1 further shows the cloud point pressure curve of a spin fluid comprising 15 wt% polyethylene A and a spin agent of n-pentane and perfluorohexane in a 90:10 ratio by weight (comparative example 2).

[0144] Figure 1 further shows the cloud point pressure curve of a spin fluid comprising 15 wt% polyethylene A and a spin agent of 1 -fluoropentane (example 1).

[0145] These spin fluids comprising 15 wt% polyethylene show cloud point pressure curves suitable for flash spinning. The cloud point pressure of the spin fluid of example 1 using 1- fluoropentane as the spin agent is significantly lower compared to the cloud point of the spin fluid of comparative examples 1 and 2 using n-pentane alone or in combination with perfluorohexane as the spin agent. The lower cloud point pressure is desirable for the operation of a commercial asset.

[0146] Example 2 and Comparative Example 3: Cloud point pressure study of polyethylene and polypropylene

[0147] Figure 2 shows the cloud point pressure curve of a spin fluid comprising 13 wt% polypropylene A and a spin agent of 1 -fluorobutane (example 2). Figure 2 further shows the cloud point pressure curve of a spin fluid comprising 12 wt% polypropylene B and a spin agent of n-butane (comparative example 3).

[0148] These spin fluids comprising 12 or 13 wt% polypropylene show cloud point pressure curves suitable for flash spinning. The cloud point pressure of the spin fluid of example 2 using 1 -fluorobutane as the spin agent is significantly lower compared to the cloud point of the spin fluid of comparative example 3 using n-butane as the spin agent. The lower cloud point pressure is desirable for the operation of a commercial asset.

[0149] Examples 3 and 4: Cloud point pressure study of polyethylene

[0150] Figure 3 shows the cloud point pressure curve of a spin fluid comprising 24 wt% polyethylene C and a spin agent of 1 -fluoropentane and n-pentane in a 50:50 ratio by weight (example 3). This spin fluid comprising 24 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0151] Figure 3 further shows the cloud point pressure curve of a spin fluid comprising 18 wt% polyethylene A and a spin agent of 1 -fluoropentane, n-pentane and cyclopentane in a 50:30:20 ratio by weight (example 4). This spin fluid comprising 18 wt% polyethylene shows a cloud point pressure curve suitable for flash spinning.

[0152] Example 6: Flash spinning experiments F-1 to F-7

[0153] Flash spinning was performed on the equipment described above. The spin agent composition, polymer type, polymer concentration, spin temperature, and spin pressure are summarized in below tables.

[0154] Table A: Summary of the flash spinning (polyethylene or polypropylene)

[0155] Table B: Summary of the flash spinning (polyethylene) with multi-component spin agents

[0156] The spin agents used in the examples exhibit a desirably low GWP value of 1 or less. This makes these compositions suitable as replacements for spin agents disclosed in the prior art.

[0157] In addition, the above examples illustrate that the compositions can be used as a spin agent for the flash spinning process of different polyolefins for different polymer concentrations, spin temperatures, and spin pressures. In particular, when using the spin agents as described herein it is possible to spin at lower spin pressures which is desirable for the operation of a commercial asset.

[0158] OTHER EMBODIMENTS

[0159] 1 . In some embodiments, the present application provides a spin fluid for flash spinning comprising (a) from about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and (b) a spin agent, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

[0160] 2. The spin fluid of embodiment 1 , wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1 -pentene), and blends / mixtures thereof, or wherein the polyolefin is a blend comprising polyethylene, a blend comprising polypropylene, a blend comprising polybutene-1 , or a blend comprising poly(4- methyl-1 -pentene).

[0161] 3. The spin fluid of embodiment 1 or 2, wherein the polyolefin is selected from the group consisting of polyethylene (PE), polypropylene (PP), and blends / mixtures thereof.

[0162] 4. The spin fluid of any of embodiments 1 to 3, 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). 5. The spin fluid of any one of embodiments 1 to 4 comprising about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent of a polyethylene, each based on the total amount of the spin fluid.

[0163] 6. The spin fluid of any one of embodiments 1 to 5 comprising about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid.

[0164] 7. The spin fluid of any one of embodiments 1 to 6 comprising from about 75 to about 92 weight percent of the spin agent, or from about 78 to about 88 weight percent of the spin agent, or from about 80 to about 86 weight percent of the spin agent, or from about 82 to about 88 weight percent of the spin agent, or from about 78 to about 82 weight percent of the spin agent, each based on the total amount of the spin fluid.

[0165] 8. The spin fluid of any one of embodiments 1 to 3 comprising about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 of a percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid.

[0166] 9. The spin fluid of embodiment 8 comprising from about 75 to about 90 weight percent of the spin agent, or from about 80 to about 90 weight percent of the spin agent, or from about 85 to about 90 weight percent of the spin agent, or from about 80 to about 85 weight percent of the spin agent, each based on the total amount of the spin fluid.

[0167] 10. The spin fluid of any of embodiments 1 to 9, wherein the at least one monofluorohydrocarbon with 4 or 5 carbon atoms is selected from the group consisting of 1- fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane, and mixtures thereof.

[0168] 1 1. The spin fluid of any of embodiments 1 to 10, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof.

[0169] 12. The spin fluid of any of embodiments 1 to 1 1 , wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane and mixtures thereof.

[0170] 13. The spin fluid of any of embodiments 1 to 12, wherein the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane.

[0171] 14. The spin fluid of any of embodiments 1 to 12, wherein the spin agent comprises, consists essentially of, or consists of 2-fluorobutane.

[0172] 15. The spin fluid of any of embodiments 1 to 12, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylpropane.

[0173] 16. The spin fluid of any of embodiments 1 to 12, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylpropane.

[0174] 17. The spin fluid of any of embodiments 1 to 1 1 , wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1- fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3- methylbutane, 1-fluoro-2,2-dimethylpropane, and mixtures thereof.

[0175] 18. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane.

[0176] 19. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoropentane.

[0177] 20. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 3-fluoropentane. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylbutane.

[0178] 22. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-3-methylbutane.

[0179] 23. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylbutane.

[0180] 24. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoro-3-methylbutane.

[0181] 25. The spin fluid of embodiment 17, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-2,2-dimethylpropane.

[0182] 26. The spin fluid of any of embodiments 1 to 1 1 , wherein the spin agent comprises, consists essentially of, or consists (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms.

[0183] 27. The spin fluid of embodiment 26, wherein the at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms is selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2- methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2- butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0184] 28. The spin fluid of embodiment 26 or 27, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof

[0185] 29. The spin fluid of any one of embodiments 26 to 28, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2 methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 carbon atoms is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0186] 30. The spin fluid of any one of embodiments 26 to 29, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2- methyl-1 -butene, and mixtures thereof.

[0187] 31 . The spin fluid of any one of embodiments 26 to 28, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-

[0188] 1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane,

[0189] 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent.

[0190] 32. The spin fluid of any one of embodiments 26 to 31 , wherein the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 50 to about 90 weight percent of at least one monofluorohydrocarbon with 4 or 5 carbon atoms, selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and from about 70 to more than about 0 weight percent, or from about 50 to about 10 weight percent of at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0191] 33. The spin fluid of any one of embodiments 26 to 32, wherein the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane and n-pentane.

[0192] 34. The spin fluid of embodiment 33, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 40 to about 90 weight percent, or from about 50 to about 70 weight percent of 1- fluoropentane, and from about 70 to more than about 0 weight percent, or from about 60 to about 10 weight percent, or from about 50 to about 30 weight percent of n-pentane.

[0193] 35. The spin fluid of any one of embodiments 26 to 32, wherein the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, n-pentane and cyclopentane.

[0194] 36. The spin fluid of embodiment 35, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1 -fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of n-pentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane.

[0195] 37. The spin fluid of embodiment 35 or 36, wherein the amount of 1 -fluorobutane, n- pentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0196] 38. The spin fluid of any one of embodiments 26 to 32, wherein the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, 2-methylpentane and cyclopentane.

[0197] 39. The spin fluid of embodiment 38, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1 -fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of 2-methylpentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane.

[0198] 40. The spin fluid of embodiment 38 or 39, wherein the amount of 1 -fluorobutane, 2- methylpentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0199] 41. The spin fluid of any one of embodiments 1 to 40, wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof.

[0200] 42. The spin fluid of any one of embodiments 1 to 41 , wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1-fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane, and mixtures thereof.

[0201] 43. The spin fluid of any one of embodiments 1 to 41 , wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

[0202] 44. The spin fluid of any one of embodiments 1 to 41 , wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0203] 45. The spin fluid of any one of embodiments 1 to 44, 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), and wherein the spin agent comprises, consists essentially of, or consists of (a) 1 -fluoropentane, or (b) 1 -fluoropentane and n-pentane, or (c) 1-fluorobutane, n-pentane and cyclopentane.

[0204] 46. The spin fluid of any one of embodiments 1 to 40, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1-fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof.

[0205] 47. The spin fluid of any one of embodiments 1 to 40, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2- fluoro-2-methylpropane and mixtures thereof.

[0206] 48. The spin fluid of any one of embodiments 1 to 40, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2- methyl-1 -butene, and mixtures thereof.

[0207] 49. The spin fluid of any one of embodiments 1 to 40, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-

[0208] 1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane,

[0209] 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent. 50. In some embodiments, the present application provides a process for the preparation of plexifilamentary fibrils of polyolefin which comprises the steps of:

[0210] (i) generating a spin fluid comprising

[0211] (a) from about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and

[0212] (b) a spin agent, and

[0213] (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 polyolefin, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

[0214] 51 . The process of embodiment 50, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1 -pentene), and blends / mixtures thereof, or wherein the polyolefin is a blend comprising polyethylene, a blend comprising polypropylene, a blend comprising polybutene-1 , or a blend comprising poly(4- methyl-1 -pentene).

[0215] 52. The process of embodiment 50 or 51 , wherein the polyolefin is selected from the group consisting of polyethylene (PE), polypropylene (PP), and blends / mixtures thereof.

[0216] 53. The process of any of embodiments 50 to 52, 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).

[0217] 54. The process of any one of embodiments 50 to 53, wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent of a polyethylene, each based on the total amount of the spin fluid.

[0218] 55. The process of any one of embodiments 50 to 54, wherein the spin fluid comprises about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid. 56. The process of any one of embodiments 50 to 55, wherein the spin fluid comprises from about 75 to about 92 weight percent of the spin agent, or from about 78 to about 88 weight percent of the spin agent, or from about 80 to about 86 weight percent of the spin agent, or from about 82 to about 88 weight percent of the spin agent, or from about 78 to about 82 weight percent of the spin agent, each based on the total amount of the spin fluid.

[0219] 57. The process of any one of embodiments 50 to 52, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 of a percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid.

[0220] 58. The process of embodiment 57, wherein the spin fluid comprises from about 75 to about 90 weight percent of the spin agent, or from about 80 to about 90 weight percent of the spin agent, or from about 85 to about 90 weight percent of the spin agent, or from about 80 to about 85 weight percent of the spin agent, each based on the total amount of the spin fluid.

[0221] 59. The process of any of embodiments 50 to 58, wherein the at least one monofluorohydrocarbon with 4 or 5 carbon atoms is selected from the group consisting of 1- fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane, and mixtures thereof.

[0222] 60. The process of any of embodiments 50 to 59, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof.

[0223] 61. The process of any of embodiments 50 to 60, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane and mixtures thereof. 62. The process of any of embodiments 50 to 61 , wherein the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane.

[0224] 63. The process of any of embodiments 50 to 61 , wherein the spin agent comprises, consists essentially of, or consists of 2-fluorobutane.

[0225] 64. The process of any of embodiments 50 to 61 , wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylpropane.

[0226] 65. The process of any of embodiments 50 to 61 , wherein the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylpropane.

[0227] 66. The process of any of embodiments 50 to 60, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1- fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3- methylbutane, 1-fluoro-2,2-dimethylpropane, and mixtures thereof.

[0228] 67. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane.

[0229] 68. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoropentane.

[0230] 69. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 3-fluoropentane.

[0231] 70. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-2-methylbutane.

[0232] 71 . The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-3-methylbutane.

[0233] 72. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoro-2-methylbutane. 73. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 2-fluoro-3-methylbutane.

[0234] 74. The process of embodiment 66, wherein the spin agent comprises, consists essentially of, or consists of 1-fluoro-2,2-dimethylpropane.

[0235] 75. The process of any of embodiments 50 to 60, wherein the spin agent comprises, consists essentially of, or consists (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms.

[0236] 76. The process of embodiment 75, wherein the at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms is selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2- methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2- butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0237] 77. The process of embodiment 75 or 76, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0238] 78. The process of any one of embodiments 75 to 77, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2 methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 carbon atoms is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0239] 79. The process of any one of embodiments 75 to 78, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2- methyl-1 -butene, and mixtures thereof.

[0240] 80. The process of any one of embodiments 75 to 77, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-

[0241] 1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane,

[0242] 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent. 81 . The process of any one of embodiments 75 to 78, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 50 to about 90 weight percent of at least one monofluorohydrocarbon with 4 or 5 carbon atoms, selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro- 2-methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and from about 70 to more than about 0 weight percent, or from about 50 to about 10 weight percent of at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1-pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1-butene, 1-hexene, cyclohexane and mixtures thereof.

[0243] 82. The process of any one of embodiments 75 to 81 , wherein the spin agent comprises, consists essentially of, or consists of 1 -fluoropentane and n-pentane.

[0244] 83. The process of embodiment 82, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to less than about 100 weight percent, or from about 40 to about 90 weight percent, or from about 50 to about 70 weight percent of 1 -fluoropentane, and from about 70 to more than about 0 weight percent, or from about 60 to about 10 weight percent, or from about 50 to about 30 weight percent of n-pentane.

[0245] 84. The process of any one of embodiments 75 to 81 , wherein the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, n-pentane and cyclopentane.

[0246] 85. The process of embodiment 84, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1 -fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of n-pentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane.

[0247] 86. The process of embodiment 84 or 85, wherein the amount of 1 -fluorobutane, n- pentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0248] 87. The process of any one of embodiments 75 to 81 , wherein the spin agent comprises, consists essentially of, or consists of 1 -fluorobutane, 2-methylpentane and cyclopentane.

[0249] 88. The process of embodiment 87, wherein the spin agent comprises, consists essentially of, or consists of from about 30 to about 95 weight percent, or from about 40 to about 80 weight percent, or from about 50 to about 60 weight percent of 1 -fluorobutane, from about 65 to about 4 weight percent, or from about 55 to about 15 weight percent, or from about 35 to about 25 weight percent of 2-methylpentane, and from about 30 to about 1 weight percent, or from about 25 to about 5 weight percent, or from about 25 to about 15 weight percent of cyclopentane.

[0250] 89. The process of embodiment 87 or 88, wherein the amount of 1 -fluorobutane, 2- methylpentane, and cyclopentane totals at least about 93 weight percent, or at least about 95 weight percent, or at least about 97 weight percent, or about 100 weight percent, each based on the total amount of the spin agent.

[0251] 90. The process of any one of embodiments 50 to 89, wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof.

[0252] 91. The process of any one of embodiments 50 to 90, wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 5 carbon atoms selected from the group consisting of 1 -fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane, and mixtures thereof.

[0253] 92. The process of any one of embodiments 50 to 90, wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1 -hexene, cyclohexane and mixtures thereof.

[0254] 93. The process of any one of embodiments 50 to 90, wherein the spin fluid comprises about 8 to about 25 weight percent, or about 12 to about 22 weight percent, or about 14 to about 20 weight percent, or about 12 to about 18 weight percent, or about 18 to about 22 weight percent of a polyethylene, each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1 -hexene, cyclohexane and mixtures thereof, wherein the amount of cyclic hydrocarbons with 5 or 6 is about 30 percent by weight or less, or about 0.5 to about 30 weight percent, or about 5 to about 30 weight percent, or about 0.5 weight percent to about 20 weight percent, or about 5 weight percent to about 20 weight percent, based on total amount of the spin agent.

[0255] 94. The process of any one of embodiments 50 to 93, 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), and wherein the spin agent comprises, consists essentially of, or consists of (a) 1-fluoropentane, or (b) 1 -fluoropentane and n-pentane, or (c) 1 -fluorobutane, n-pentane and cyclopentane.

[0256] 95. The process of any one of embodiments 50 to 89, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1-fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof.

[0257] 96. The process of any one of embodiments 50 to 89, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of at least one monofluorohydrocarbon with 4 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2- fluoro-2-methylpropane and mixtures thereof.

[0258] 97. The process of any one of embodiments 50 to 89, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2- methyl-1 -butene, and mixtures thereof.

[0259] 98. The process of any one of embodiments 50 to 89, wherein the spin fluid comprises about 10 to about 25 weight percent, or about 10 to about 20 weight percent, or about 10 to about 15 weight percent, or about 15 to about 20 weight percent of a polyolefin, selected from a polypropylene, a polybutene-1 , or a poly(4-methyl-1 -pentene), each based on the total amount of the spin fluid, and a spin agent, wherein the spin agent comprises, consists essentially of, or consists of (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2- methylpropane, 2-fluoro-2-methylpropane, 1 -fluoropentane, 2-fluoropentane, 3- fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3-methylbutane, 2-fluoro-2-methylbutane, 2- fluoro-3-methylbutane, 1-fluoro-2,2-dimethylpropane and mixtures thereof, (2) at least one saturated or unsaturated, linear or branched hydrocarbon with 5 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, 2-methyl-2-butene, 2-methyl-

[0260] 1 -butene, and mixtures thereof and (3) at least one saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms, selected from the group consisting of n-hexane,

[0261] 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 1-hexene, cyclohexane and mixtures thereof, wherein the amount of saturated or unsaturated, linear or branched hydrocarbon with 6 carbon atoms is about 20 percent by weight or less, or about 0.5 to about 20 weight percent, or about 5 to about 20 weight percent, based on total amount of the spin agent.

[0262] 99. In some embodiments, the present application provides a use of the spin fluid of any of embodiments 1 to 49 for preparing of plexifilamentary fibrils of polyolefin by flash spinning.

[0263] 100. The plexifilamentary fibrils of polyolefin obtainable by the process of any one of embodiments 50 to 98.

[0264] 101. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polyolefin of embodiment 100. 102. The sheet of embodiment 101 , wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

[0265] 103. A bonded sheet obtainable by thermally or mechanically bonding the consolidated sheet of embodiment 102.

[0266] 104. A softened sheet obtainable by softening the consolidated sheet of embodiment 102 or by softening the bonded sheet of embodiment 103.

[0267] 105. A multilayer sheet comprising two or more sheets, wherein at least one sheet is a sheet according to any one of embodiments 101 to 104.

[0268] 106. An article comprising plexifilamentary fibrils of polyolefin of embodiment 100 and / or a sheet of any one of embodiments 101 to 104 and / or a multilayer sheet of embodiment 105.

[0269] 107. The article of embodiment 106 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.

[0270] 108. The article of embodiment 107, wherein the garment is protective apparel.

[0271] 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 spin fluid for flash spinning comprising(a) from about 8 to about 25 weight percent of a polyolefin, based on the total amount of the spin fluid, and(b) a spin agent, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

2. The spin fluid of claim 1 , wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1-pentene), and blends / mixtures thereof.

3. The spin fluid of any one of claims 1 or 2, wherein the at least one monofluorohydrocarbon with 4 or 5 carbon atoms is selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane, and mixtures thereof.

4. The spin fluid of any one of claims 1 to 3, wherein the spin agent comprises (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

5. A process for the preparation of plexifilamentary fibrils of polyolefin which comprises the steps of:(i) generating a spin fluid comprising(a) from about 8 to about 25 weight percent of a polyolefin, 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 polyolefin, wherein the spin agent comprises at least one monofluorohydrocarbon with 4 or 5 carbon atoms.

6. The process of claim 5, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, polybutene-1 , poly(4-methyl-1 -pentene), and blends / mixtures thereof.

7. The process of any one of claims 5 or 6, wherein the at least one monofluorohydrocarbon with 4 or 5 carbon atoms is selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane, and mixtures thereof.

8. The process of any one of claims 5 to 7, wherein the spin agent comprises (1) at least one monofluorohydrocarbon with 4 or 5 carbon atoms selected from the group consisting of 1 -fluorobutane, 2-fluorobutane, 1-fluoro-2-methylpropane, 2-fluoro-2-methylpropane, 1- fluoropentane, 2-fluoropentane, 3-fluoropentane, 1-fluoro-2-methylbutane, 1-fluoro-3- methylbutane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, 1-fluoro-2,2- dimethylpropane and mixtures thereof, and (2) at least one saturated or unsaturated, linear, branched or cyclic hydrocarbon with 5 or 6 carbon atoms, selected from the group consisting of n-pentane, 1 -pentene, 2-methylbutane, cyclopentane, n-hexane, 2-methylpentane, 3- methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methyl-2-butene, 2-methyl-1- butene, 1-hexene, cyclohexane and mixtures thereof.

9. Use of the spin fluid of any one of claims 1 to 4 for preparing of plexifilamentary fibrils of polyolefin by flash spinning.

10. Plexifilamentary fibrils of polyolefin obtainable by the process of any one of claims 5 to 8.

11. A sheet of nonwoven flash-spun plexifilamentary fibrils comprising plexifilamentary fibrils of polyolefin of claim 10.

12. The sheet of claim 11 , wherein the sheet is a collected sheet, a consolidated sheet, a bonded sheet, or a softened sheet.

13. An article comprising the plexifilamentary fibrils of polyolefin of claim 10 and / or the sheet of claim 11 or 12.

14. The article of claim 13 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.

Images