A film having a reduced shutdown temperature and a polymer composition for producing the same film.

Abstract

A polymer composition for producing gel extrusion articles is described. The polymer composition contains polyethylene particles combined with a plasticizer and one or more shutdown-reducing additives. The shutdown-reducing additives reduce the shutdown temperature of polymer articles made from the polymer composition. In one embodiment, the polymer composition is used to form a porous membrane for use as a battery separator.

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application is based on and claims priority to U.S. Provisional Patent Application No. 63 / 018,924, filed 1 May 2020, and U.S. Provisional Patent Application No. 63 / 107,072, filed 29 October 2020, both of which are incorporated herein by reference. [Background technology]

[0002]

[0002] Polyethylene polymers have numerous and diverse uses and applications. For example, high-density polyethylene is a useful engineering plastic with a unique combination of abrasion resistance, surface lubricity, chemical resistance, and impact strength. They have found applications in the manufacture of high-strength fibers for use in ropes and bulletproof molded articles, as well as in the manufacture of other elongated articles, such as membranes for electronic devices. However, because the fluidity of these materials in a molten state decreases as the molecular weight increases, processing by conventional techniques, such as melt extrusion, is not always feasible.

[0003]

[0003] One alternative method for producing fibers and other elongated components from polyethylene polymer is by gel treatment, in which the polymer is combined with a solvent. The resulting gel can be extruded into fibers or membranes and stretched in one or two directions. Some or all of the solvent can also be removed from the product.

[0004]

[0004] Membranes made from polyethylene polymers through gel treatment can be formed to have many beneficial properties. For example, the membranes can be formed with micropores. Microporous polyethylene membranes formed through gel treatment are particularly suitable for use, for example, as separators in batteries, such as lithium-ion batteries. Microporous membranes can, for example, separate the anode from the cathode and prevent short circuits between active battery components. At the same time, due to the porous nature of the material, microporous membranes allow ions to pass through. The ion permeability of microporous polyethylene membranes makes the material particularly suitable for controlling electrochemical reactions within batteries.

[0005]

[0005] In addition to the microporous properties of the polyethylene film, as well as its beneficial strength and other physical properties, the polyethylene film also possesses what is known in the art as an effective "shutdown effect." The shutdown effect refers to the fact that when it exceeds a certain temperature, the micropores within the polyethylene separator close on their own. When the pores in the polyethylene film close upon reaching a certain temperature, ions can no longer pass through the film, and the electrochemical function of the battery ceases. This effect is an important safety property for the battery because it prevents thermal runaway reactions from continuing and prevents the battery from overheating and creating potentially harmful conditions. [Overview of the project] [Problems that the invention aims to solve]

[0006]

[0006] Microporous membranes made from high molecular weight polyethylene polymers inherently possess lower shutdown temperatures than many other materials, but there is a desire in the art for polyethylene membranes to have even lower shutdown temperatures without compromising their physical properties. In fact, even a small decrease in the shutdown temperature of a material can provide a dramatic improvement in battery safety and other functions. Unfortunately, when efforts are made to lower the shutdown temperature, other properties of the membrane may be adversely affected. Therefore, there is a need for methods and techniques to lower the shutdown temperature of polyethylene membranes without adversely affecting other properties of the material. [Means for solving the problem]

[0007]

[0007] Generally, this disclosure covers polyolefin compositions suitable for gel processing applications. More specifically, this disclosure covers polymer compositions containing high-density polyethylene polymers suitable for producing microporous ion-permeable membranes that can be used as separators in batteries. According to this disclosure, the polymer compositions are formulated to have a lower shutdown temperature so that once the membrane is exposed to higher temperatures in a particular environment, the membrane becomes substantially impermeable. For example, when used as a battery separator, the shutdown temperature of the membrane can prevent the battery from thermal runaway.

[0008]

[0008] In one embodiment, the present disclosure relates to a polymer composition for manufacturing a gel extruded article. The polymer composition comprises a plasticizer, high-density polyethylene particles, and a shutdown-reducing additive. The shutdown-reducing additive comprises particles combined with the high-density polyethylene particles and the plasticizer.

[0009]

[0009] In one embodiment, the shutdown-reducing additive reduces the shutdown temperature to at least about 1.4°C lower than that of a polymer composition in which the shutdown-reducing additive is replaced by a further amount of polyethylene particles, for example, at least about 1.8°C lower, for example at least about 2.2°C lower, for example at least about 2.5°C lower. In other embodiments, the shutdown-reducing additive reduces the shutdown temperature of the polymer composition by more than about 3°C, for example at more than 4°C, for example at more than 5°C, for example at more than 6°C, for example at more than 7°C. The shutdown-reducing temperature of the polymer composition is generally reduced to about 20°C or less, for example at more than 15°C or less, for example at more than 10°C or less.

[0010]

[0010] The shutdown-reducing additive may include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, polyethylene wax, hydrogenated fatty acid, fatty acid amide, medium-density polyethylene, fatty acid dimer, plastomer, elastomer, or mixtures thereof, in relation to the main high-density polyethylene particles present in the composition. In one embodiment, the shutdown-reducing additive is a polyethylene polymer having a melt flow rate of about 0.01 g / 10 min to about 70 g / 10 min, for example about 0.05 g / 10 min to about 50 g / 10 min, for example about 0.1 g / 10 min to about 30 g / 10 min, for example about 1 g / 10 min to about 20 g / 10 min. The shutdown-reducing additive can be present in the polymer composition in an amount of about 10% to about 40% by weight, for example, about 15% to about 35% by weight, for example, about 20% to about 30% by weight.

[0011]

[0011] In one embodiment, the high-density polyethylene particles may have a medium volume particle size of less than about 150 microns, for example less than about 125 microns, and may generally have a medium volume particle size of more than about 50 microns. On the other hand, the shutdown-reducing additive may be in the form of particles having a medium volume particle size of less than about 800 microns, for example less than about 600 microns, for example less than about 400 microns, for example less than about 200 microns, and may generally have a medium volume particle size of more than about 25 microns, for example more than about 50 microns.

[0012]

[0012] Generally, polymer compositions contain high-density polyethylene resin in amounts up to about 50% by weight, for example, in amounts of about 0.5% to about 15% by weight, for example, about 2% to about 8% by weight. Plasticizers may be present in the composition in amounts greater than about 50% by weight, for example, greater than about 60% by weight, for example, greater than about 70% by weight, for example, greater than about 80% by weight, for example, less than about 90% by weight. A wide variety of different materials can be used as plasticizers. For example, plasticizers may include mineral oil, paraffinic oil, hydrocarbon oil, alcohol, etc. For example, plasticizers may include decalin, xylene, dioctyl phthalate, dibutyl phthalate, stearyl alcohol, oleyl alcohol, decyl alcohol, nonyl alcohol, diphenyl ether, n-decane, n-dodecane, or mixtures thereof. In one embodiment, the plasticizer may include C5-C12 hydrocarbons, such as C5-C12 saturated hydrocarbons. For example, the plasticizer may include heptane, hexane, paraffin, and the like.

[0013]

[0013] In one embodiment, the high-density polyethylene used to manufacture the particles can have a relatively high molecular weight. The use of high molecular weight polyethylene particles can be beneficial, particularly in applications where greater strength properties are required or desired. For example, the polyethylene used to manufacture the particles can have a molecular weight greater than about 500,000 g / mol, such as greater than about 700,000 g / mol, such as greater than about 1,000,000 g / mol, such as greater than about 1,500,000 g / mol, and can have a molecular weight less than about 4,000,000 g / mol, such as less than about 3,500,000 g / mol. In one embodiment, the polyethylene used to manufacture the particles comprises Ziegler-Natta catalyst high molecular weight polyethylene.

[0014]

[0014] The present disclosure also encompasses polymer articles formed from the above polymer compositions. The polymer articles can be manufactured through a gel extrusion method or a gel spinning method. Polymer articles made in accordance with the present disclosure include fibers, films, such as membranes, and the like.

[0015]

[0015] During the formation of the polymer article, a substantial portion of the plasticizer is removed. For example, in one aspect, more than 95 wt%, such as more than about 98 wt% of the plasticizer is removed during the formation of the polymer article. As a result, polymer articles made in accordance with the present disclosure generally contain high-density polyethylene combined with a shutdown degrading additive. For example, the resulting polymer article can contain the high-density polyethylene polymer in an amount of about 60 wt% to about 98 wt%, such as in an amount of about 65 wt% to about 97 wt%. The shutdown degrading additive can be present in the polymer article in an amount of about 2 wt% to about 40 wt%, such as in an amount of about 3 wt% to about 35 wt%, such as in an amount of about 4 wt% to about 10 wt%.

[0016]

[0016] The disclosure also covers methods for producing polymer articles. The method includes the step of forming a gel-like composition from the polymer compositions described above. The gel-like composition is then extruded through a die to form a polymer article. The polymer article may include, for example, fibers, continuous films, or discontinuous films, such as porous membranes. During the formation of the polymer article, at least a portion of the plasticizer is separated and removed from the polyethylene article. For example, in one embodiment, more than 80%, e.g., more than 90%, e.g., more than 95%, e.g., more than 98% of the plasticizer is removed during the formation of the polymer article.

[0017]

[0017] In one embodiment, an extraction solvent, such as dichloromethane, is combined with the polymer composition before or during the formation of the polymer article. The extraction solvent may be used to facilitate the removal of plasticizers.

[0018]

[0018] Other features and aspects of this disclosure are described in more detail below.

[0019] This disclosure can be better understood by referring to the following drawings. [Brief explanation of the drawing]

[0019] [Figure 1]

[0020] This is a plot or graph illustrating the shutdown temperature of a microporous membrane using impedance testing. [Figure 2]

[0021] This is a cross-sectional view of an electronic device, such as a battery, incorporating a porous membrane fabricated in accordance with this disclosure.

[0020]

[0022] The repeated use of reference letters in this specification and in these drawings is intended to represent identical or similar features or elements of the present invention.

[0021] definition

[0023] The shutdown temperature of polymer articles, such as microporous films, can vary depending on the type of test and equipment used to measure it. In fact, shutdown temperatures can vary widely depending on the procedure, the molecular weight of the base resin, and the instruments used to determine it. Therefore, any reported shutdown temperature for a variety of products may be much lower than the actual shutdown temperature if different tests or techniques were used.

[0022]

[0024] In this disclosure, the shutdown temperature of a polymer article, such as a porous membrane, or a polymer composition may be determined in accordance with "impedance testing," "thermomechanical analysis," and "suggestive scanning calorimetry." However, impedance testing is the only test that directly measures the shutdown temperature. The following tests are defined as follows:

[0023]

[0025] Impedance test

[0026] The impedance spectroscopy test setup consists of a glass measuring cell with two steel electrodes. According to impedance spectroscopy, the sample is immersed in an electrolyte (1M LiPF6 in ethylene carbonate / dimethyl carbonate 1:1) and collected in the cell between the electrodes. The measuring cell is then coupled to an impedance spectrometer that records the impedance spectrum every 50 seconds at frequencies between 100 Hz and 100 kHz. The measuring cell is then placed in an oven and heated from 110°C to 150°C for 2 hours, during which time the impedance spectrum is continuously recorded. Data evaluation is performed by plotting impedance versus temperature, with the shutdown temperature indicated by the midpoint of the steepest increase in impedance. An example plot is shown in Figure 1, where the arrow indicates the shutdown temperature. The test can be performed using the HCP-803 potentiostat, available from Biologic Science Instruments.

[0024]

[0027] Thermomechanical analysis (TMA test)

[0028] Under the TMA method, dynamic strain is measured while the sample is subjected to a temperature regime and a static force of 0.2 N with a force multiplier of 0.5. The test is performed at a heating rate of 2 °C / min over temperatures ranging from room temperature (25–30 °C) to 160 °C. The frequency is set to 0.1 Hz. Data evaluation is performed by plotting dynamic strain against temperature, with the softening point indicated by the dynamic strain inflection point. The test can be performed using a Perkin Elmer DMA8000 dynamic mechanical analyzer.

[0025]

[0029] Suggested Scanning Calorimetry (DSC test)

[0030] Suggestion: Using scanning calorimetry (DSC), the melting point of a sample can be determined by ISO Test No. 11357 under the following conditions: The sample is heated from 0°C to 180°C at a heating rate of 10°C / min and held isothermally at 180°C for 5 minutes. After isothermally holding, the sample is cooled to 0°C at a heating rate of 10°C / min. Finally, the sample is heated to 180°C at a heating rate of 20°C. The sample is inactivated with nitrogen throughout all steps of the DSC procedure. This test can be performed using a DSC Q2000 calorimeter available from TA Instruments.

[0026]

[0031] When used in this specification, Puncture strength The puncture strength is measured in accordance with ASTM Test D3763 and measures the film's ability to resist foreign particles causing holes or defects. The test is performed using a test apparatus, such as the Instron CEAST9340 apparatus. The drop height is 0.03 to 1.10 m. The impact velocity is 0.77 to 4.65 m / sec. The maximum drop mass is 37.5 kg and the maximum potential energy is 405 J. Puncture strength is measured in a low-velocity puncture mode at 1.67 mm / sec.

[0027]

[0032] polymer or polymer composition Meltflow rate This is measured in accordance with ISO Test 1133, at 190°C with a load of 2.16 kg (unless otherwise specified).

[0028]

[0033] polymer density It conforms to ISO Test 1183, g / cm 3 It is measured in units of [unit name].

[0034] Average particle size (d50) is measured using laser diffraction / light scattering, for example, a suitable HORIBA light scattering instrument.

[0029]

[0035] polymer average molecular weight This is determined using Margolies' equation.

[0036] Tensile coefficient, yield point tensile stress, yield point tensile strain, 50% fracture point tensile stress, fracture point tensile stress, and fracture point nominal tensile strain. All measurements are performed in accordance with ISO Test527-2 / 1B.

[0030]

[0037] Garley air permeability This can be measured in accordance with the Gurley test using a Gurley densometer, such as the Gurley Densometer, Model KRK2060c, commercially available from Kumagai Riki Kogyo Co., Ltd. The test is performed in accordance with ISO Test 5636. The Gurley test measures air permeability as a function of the time required for a specific amount of air to pass through a specific area under a specific pressure. The unit is reported in seconds / 100 ml.

[0031]

[0038] Porosity (%) is measured according to the following procedure. During this procedure, the following ASTM Standards are used as reference materials: D622 Standard Test Method for Apparent Density of Rigid Cellular Plastics¹ and D729 Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement¹. The following instruments are used: Calibrated Analytical Balance (0.0001 gram); Lorentzen & Wettre Micrometer, code 251 (0.1 um); and Deli 2056 art knife.

[0032] procedure: 1.1. Samples and Sample Preparation Using an art knife for specimens, each sample material is cut into at least three specimens measuring 60mm ± 0.5 × 60mm ± 0.5mm. 1.2. Equipment and Measurement 3.2.1 Using an L&W micrometer, take five thickness readings (an average of five readings) for each 60mm x 60mm specimen. Record this value as the thickness of the specimen. 3.2.2 Weigh the specimen directly on a scale. Record this value as the weight of the specimen. 3.2.3 Place three samples of the same sample together and repeat steps 2.2.1 and 3.2.2 to obtain the bulk thickness and bulk weight. The density is calculated into three significant numbers as follows: aD film = density (film) = Wt. of the specimen. / THK×Square D film = density of the specimen, mg / mm³ Wt = weight of the sample, mg THK = Thickness of specimen, mm Square = area of ​​the sample (mm²) bD polymer = Density (polymer) 0.95 (g / cm³) D polymer: Raw material density, no pores. c. Porosity = (1 - D film / D polymer) × 100% [Modes for carrying out the invention]

[0033]

[0039] Those skilled in the art will understand that this study describes only exemplary embodiments and is not intended to limit broader aspects of the present disclosure.

[0040] Generally, this disclosure relates to polymer compositions suitable for producing gel extruded articles, such as fibers and films having porous membranes. The polymer compositions contain polyethylene resin, such as high-density polyethylene particles, combined with a plasticizer and a shutdown-reducing additive. According to this disclosure, the shutdown-reducing additive includes particles combined with high-density polyethylene particles and reduces the shutdown temperature of the membrane when the composition is formed into a porous membrane. Particularly advantageous, the shutdown-reducing additive can be incorporated into the polymer composition in relatively large quantities without affecting the physical or mechanical properties of the articles made from the composition. Therefore, the shutdown-reducing additive can be incorporated into the polymer compositions of this disclosure without substantially affecting the mechanical properties of the membranes made from the composition.

[0034]

[0041] In general, any suitable high-density polyethylene polymer can be used to form the main polymer component and matrix polymer of the polymer composition. High-density polyethylene has a density of approximately 0.93 g / cm³. 3 For example, approximately 0.94 g / cm³ 3 For example, approximately 0.95 g / cm³ 3 It has a density of the above, and is generally about 1 g / cm³. 3 It has a density of less than 1.

[0035]

[0042] High-density polyethylene polymers can be made from units derived from more than 90% ethylene, for example, more than 95% ethylene, or 100% ethylene. Polyethylene can be a copolymer containing homopolymers or terpolymers having other monomer units.

[0036]

[0043] High-density polyethylene can be high molecular weight polyethylene, very high molecular weight polyethylene, and / or ultra-high molecular weight polyethylene. "High molecular weight polyethylene" has a molecular weight of at least about 3 × 10⁻⁶. 5Refers to a polyethylene composition having an average molecular weight of g / mol, and when used herein, is intended to include very high molecular weight polyethylene and ultra-high molecular weight polyethylene. For the purposes of this specification, the molecular weights referred to herein are determined according to the Margolies equation (the "Margolies molecular weight").

[0037]

[0044] "Very high molecular weight polyethylene" refers to a polyethylene composition having a weight average molecular weight of less than about 3×10 6 g / mol and greater than about 1×10 6 g / mol. In some embodiments, the molecular weight of the very high molecular weight polyethylene composition is between about 2×10 6 g / mol and less than about 3×10 6 g / mol.

[0038]

[0045] "Ultra-high molecular weight polyethylene" refers to a polyethylene composition having an average molecular weight of at least about 3×10 [[ID=第十九]] 6 g / mol. In some embodiments, the molecular weight of the ultra-high molecular weight polyethylene composition is between about 3×10 6 g / mol and about 30×10 6 g / mol, or between about 3×10 6 g / mol and about 20×10 6 g / mol, or between about 3×10 6 g / mol and about 10×10 6 g / mol, or between about 3×10 6 g / mol and about 6×10 6 g / mol.

[0039]

[0046] In one embodiment, high-density polyethylene is a homopolymer of ethylene. In another embodiment, high-density polyethylene may be a copolymer. For example, high-density polyethylene may be a copolymer of ethylene and another olefin containing 3 to 16 carbon atoms, for example 3 to 10 carbon atoms, for example 3 to 8 carbon atoms. These other olefins include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methylpenta-1-ene, 1-decene, 1-dodecene, 1-hexadecene, and others. Also available herein are polyene comonomers, for example 1,3-hexadiene, 1,4-hexadiene, cyclopentadiene, dicyclopentadiene, 4-vinylcyclohexa-1-ene, 1,5-cyclooctadiene, 5-vinylidene-2-norbornene, and 5-vinyl-2-norbornene. However, if present, the amount of non-ethylene monomers in the copolymer may be less than about 10 mol%, for example less than about 5 mol%, for example less than about 2.5 mol%, for example less than about 1 mol%, where the mol% is relative to the total moles of monomers in the polymer.

[0040]

[0047] In one embodiment, high-density polyethylene may have a unimodal molecular weight distribution. Alternatively, high-density polyethylene may exhibit a bimodal molecular weight distribution. For example, a bimodal distribution generally refers to a polymer that has distinct higher molecular weights and distinct lower molecular weights (e.g., two distinct peaks) on a size exclusion chromatography or gel permeation chromatography curve. In another embodiment, high-density polyethylene may exhibit more than two molecular weight distribution peaks such that the polyethylene exhibits a multimodal (e.g., trimodal, tetramodal, etc.) distribution. Alternatively, high-density polyethylene may have a broad molecular weight distribution, resulting from a blend of higher molecular weight components and lower molecular weight components, such that the size exclusion chromatography or gel permeation chromatography curve does not exhibit at least two distinct peaks, but instead exhibits one distinct peak that is broader than the peaks of the individual components.

[0041]

[0048] Polyethylene can be synthesized using any method known in the art. Polyethylene powder is typically produced by catalytic polymerization of ethylene monomer, or optionally with one or more other 1-olefin comonomers, using heterogeneous catalysts and organoaluminum or magnesium compounds as co-catalysts, such that the 1-olefin content in the final polymer is 10% or less of the ethylene content. Ethylene is usually polymerized in the gas phase or slurry phase at relatively low temperatures and pressures. Polymerization reactions can be carried out at temperatures between 50°C and 100°C and pressures in the range of 0.02 to 2 MPa.

[0042]

[0049] The molecular weight of polyethylene can be adjusted by adding hydrogen. Temperature and / or the type and concentration of the co-catalyst may also be used to fine-tune the molecular weight. In addition, the reaction may be carried out in the presence of an antistatic agent to avoid fouling and product contamination.

[0043]

[0050] Suitable catalyst systems include, but are not limited to, Ziegler-Natta type catalysts. Typically, Ziegler-Natta type catalysts are derived from combinations of transition metal compounds from groups 4 to 8 of the periodic table and alkyl or hydride derivatives of metals from groups 1 to 3 of the periodic table. The transition metal derivatives used usually include metal halides or esters, or combinations thereof. Exemplary Ziegler-Natta catalysts include catalysts based on reaction products of organoaluminum or magnesium compounds, for example, alkylaluminum or magnesium, with halides or esters of titanium, vanadium, or chromium. Heterogeneous catalysts may be unsupported or supported on porous particulate materials, such as silica or magnesium chloride. Such supports may be added during catalyst synthesis or obtained as chemical reaction products of the catalyst synthesis itself.

[0044]

[0051] In one embodiment, a suitable catalyst system can be obtained by the reaction of a titanium(IV) compound with a trialkylaluminum compound in an inert organic solvent at a temperature in the range of -40°C to 100°C, preferably -20°C to 50°C. The concentrations of the starting materials are in the range of 0.1 to 9 mol / L, preferably 0.2 to 5 mol / L, for the titanium(IV) compound and in the range of 0.01 to 1 mol / L, preferably 0.02 to 0.2 mol / L, for the trialkylaluminum compound. The titanium component is added to the aluminum compound over a period of 0.1 to 60 minutes, preferably 1 to 30 minutes, and the molar ratio of titanium to aluminum in the final mixture is in the range of 1:0.01 to 1:4.

[0045]

[0052] In another embodiment, a preferred catalyst system is obtained by a one- or two-step reaction of a titanium(IV) compound with a trialkylaluminum compound in an inert organic solvent at a temperature in the range of -40°C to 200°C, preferably -20°C to 150°C. In the first step, the titanium(IV) compound is reacted with the trialkylaluminum compound at a temperature in the range of -40°C to 100°C, preferably -20°C to 50°C, using a molar ratio of titanium to alumina in the range of 1:0.1 to 1:0.8. The concentrations of the starting materials are in the range of 0.1 to 9.1 mol / L, preferably 5 to 9.1 mol / L, for the titanium(IV) compound and in the range of 0.05 to 1 mol / L, preferably 0.1 to 0.9 mol / L, for the trialkylaluminum compound. The titanium component is added to the aluminum compound over a period of 0.1 to 800 minutes, preferably 30 to 600 minutes. In the second step, if applicable, the reaction product obtained in the first step is treated with a trialkylaluminum compound and titanium in a molar ratio of 1:0.01 to 1:5 in the range of 1:0.01 to 1:5 at a temperature in the range of -10°C to 150°C, preferably 10°C to 130°C.

[0046]

[0053] In yet another embodiment, a preferred catalyst system is obtained by a procedure in which, in the first reaction step, a magnesium alkolate is reacted with titanium chloride in an inert hydrocarbon at a temperature of 50°C to 100°C. In the second reaction step, the formed reaction mixture is subjected to heat treatment at a temperature of 110°C to 200°C for about 10 to 100 hours, accompanied by the release of alkyl chloride until no more alkyl chloride is released, and the solid is then liberated from the soluble reaction product by washing several times with hydrocarbon.

[0047]

[0054] In further embodiments, silica-supported catalysts, such as the commercially available catalyst system Sylopol 5917, may also be used.

[0055] Using such catalytic systems, polymerization is typically carried out in a suspension, in one or more steps in a continuous or batch, at low pressure and temperature. The polymerization temperature is typically in the range of 30°C to 130°C, preferably in the range of 50°C to 90°C, and the partial pressure of ethylene is typically less than 10 MPa, preferably 0.05 MPa and 5 MPa. Trialkylaluminum, such as but not limited to isoprenylaluminum and triisobutylaluminum, is used as a cocatalyst such that the Al:Ti (cocatalyst vs. catalyst) ratio is in the range of 0.01 to 100:1, more preferably in the range of 0.03 to 50:1. The solvent is an inert organic solvent typically used for Ziegler-type polymerization. Examples include butane, pentane, hexane, cyclohexene, octane, nonane, decane, their isomers, and mixtures thereof. The molecular weight of the polymer is controlled through the supply of hydrogen. The ratio of the partial pressure of hydrogen to the partial pressure of ethylene is in the range of 0 to 50, preferably in the range of 0 to 10. The polymer is separated and dried under nitrogen in a fluidized bed dryer. The solvent can be removed by steam distillation if a high-boiling point solvent is used. Salts of long-chain fatty acids may be added as stabilizers. Typical examples are calcium stearate, magnesium stearate, and zinc stearate.

[0048]

[0056] Optionally, other catalysts, such as Phillips catalysts, metallocenes, and post-metallocenes, may be used. In general, co-catalysts, such as almoxanes or alkylaluminum or alkylmagnesium compounds, are also used. Other suitable catalytic systems include group IV metal complexes of phenolate ether ligands.

[0049]

[0057] According to this disclosure, high-density polyethylene polymer is formed into particles and combined with a plasticizer. In one embodiment, the polyethylene particles are made from a polyethylene polymer having a relatively low bulk density, as measured in accordance with DIN 53466. For example, in one embodiment, the bulk density is generally about 0.4 g / cm³. 3 Less than, for example, about 0.35 g / cm³ 3 Less than, for example, about 0.33 g / cm³ 3 Less than, for example, about 0.3 g / cm³ 3 Less than, for example, about 0.28 g / cm³ 3 Less than, for example, about 0.26 g / cm³ 3 It is less than 0.1 g / cm³. The bulk density is generally about 0.1 g / cm³. 3 For example, about 0.15 g / cm³ 3 It is extremely high. In one embodiment, the polymer is approximately 0.2 g / cm³. 3 ~Approx. 0.27g / cm 3 It has a bulk density of .

[0050]

[0058] In one embodiment, the polyethylene particles may be a flowable powder. These particles may have a median particle size (d50) of less than 200 microns. For example, the median particle size (d50) of polyethylene particles may be less than about 150 microns, for example, less than about 125 microns. Generally, the median particle size (d50) is greater than about 20 microns. The particle size of the powder may be measured using laser diffraction according to ISO 13320.

[0051]

[0059] In one embodiment, 90% of the polyethylene particles may have a particle size of less than approximately 250 microns. In another embodiment, 90% of the polyethylene particles may have a particle size of less than approximately 200 microns, for example, less than approximately 170 microns.

[0052]

[0060] The molecular weight of polyethylene polymers can vary depending on the specific application. Polyethylene polymers may have an average molecular weight determined, for example, by Margoly's equation. The molecular weight can be determined by first measuring the viscosity number according to DIN EN ISO Test 1628. A dry powder stream is measured using a 25 mm nozzle. The molecular weight is then calculated from the viscosity number using Margoly's equation. The average molecular weight is generally greater than approximately 300,000 g / mol, e.g., greater than approximately 500,000 g / mol, e.g., greater than approximately 700,000 g / mol, e.g., greater than approximately 1,000,000 g / mol, e.g., greater than approximately 2,000,000 g / mol, e.g., greater than approximately 2,500,000 g / mol, e.g., greater than approximately 3,000,000 g / mol, e.g., greater than approximately 4,000,000 g / mol. The average molecular weight is generally less than about 12,000,000 g / mol, for example less than about 10,000,000 g / mol. In one embodiment, the number-average molecular weight of the high-density polyethylene polymer can be less than about 4,000,000 g / mol, for example less than about 3,000,000 g / mol.

[0053]

[0061] Polyethylene may have viscosity numbers ranging from at least 100 mL / g, e.g., at least 500 mL / g, e.g., at least 1,500 mL / g, e.g., at least 2,000 mL / g, e.g., at least 4,000 mL / g, to less than about 6,000 mL / g, e.g., less than about 5,000 mL / g, e.g., less than about 4,000 mL / g, e.g., less than about 3,000 mL / g, e.g., less than about 1,000 mL / g, as determined using the concentration in 0.0002 g / mL of decahydronaphthalene in accordance with ISO 1628 part 3.

[0054]

[0062] High-density polyethylene can have a crystallinity of at least about 40% to 85%, for example, 45% to 80%.

[0063] Generally, high-density polyethylene particles are present in polymer compositions in amounts up to about 50% by weight. For example, high-density polyethylene particles can be present in polymer compositions in amounts less than about 45% by weight, for example less than about 40% by weight, for example less than about 35% by weight, for example less than about 30% by weight, for example less than about 25% by weight, for example less than about 20% by weight, for example less than about 15% by weight. Polyethylene particles can be present in compositions in amounts greater than about 5% by weight, for example greater than about 10% by weight, for example greater than about 15% by weight, for example greater than about 20% by weight, for example greater than about 25% by weight. During gel treatment, plasticizers are combined with high-density polyethylene particles, which may be substantially or completely removed during the formation of the polymer article. For example, in one embodiment, the obtained polymer article may contain high-density polyethylene polymer in an amount of more than about 70% by weight, for example more than about 80% by weight, for example more than about 85% by weight, for example more than about 90% by weight, for example more than about 95% by weight.

[0055]

[0064] According to this disclosure, a polymer composition for producing a gel extruded article contains a shutdown-reducing additive in combination with high-density polyethylene particles. The shutdown-reducing additive may also be present in the form of particles mixed or blended with the high-density polyethylene particles. Melt-blending the high-density polyethylene particles with the shutdown-reducing additive may result in undesirable consequences, such as polymer entanglement, which can make it difficult to produce a gel extruded article from the polymer composition.

[0056]

[0065] Shutdown-reducing additives are combined with high-density polyethylene particles in such a way that they reduce the shutdown temperature of the polymer composition when it is formed into an article, such as a porous membrane. The specific shutdown-reducing additive selected for an application may depend on a variety of factors, including the type of high-density polyethylene particles combined with the shutdown-reducing additive. Generally, shutdown-reducing additives may include high-density polyethylene particles, low-density polyethylene particles, linear low-density polyethylene particles, metallocene linear low-density polyethylene particles having a molecular weight distribution or polydispersity index of less than about 3, e.g., less than about 2.5, polyethylene wax particles, hydrogenated fatty acid particles, particles made from fatty acid dimers, plastomer particles, elastomer particles, and mixtures thereof, which are different from the matrix polymer.

[0057]

[0066] For example, in one embodiment, the shutdown-reducing additive may be made from a polyethylene polymer. For example, in one embodiment, the polyethylene polymer may be a high-density polyethylene polymer having a molecular weight less than that of the high-density polyethylene matrix polymer. For example, the high-density polyethylene polymer may have an average molecular weight of less than about 700,000 g / mol, for example less than about 500,000 g / mol, for example less than about 300,000 g / mol, for example less than 100,000 g / mol. The average molecular weight of high-density polyethylene polymers is generally greater than about 80,000 g / mol.

[0058]

[0067] In yet another embodiment, the shutdown-reducing additive can be medium-density polyethylene. Medium-density polyethylene is typically about 0.92 g / cm³. 3 ~Approx. 0.94g / cm 3 It can have a density of .

[0059]

[0068] In alternative embodiments, the shutdown-reducing additive can be low-density polyethylene. Low-density polyethylene may have a branched structure that distinguishes the polymer from high-density polyethylene or linear low-density polyethylene. The branching of the polymer increases transparency, increases flexibility, and facilitates the melt treatment of the polymer. The molecular weight, crystallinity, and molecular weight distribution of the low-density polyethylene can be varied depending on the specific application.

[0060]

[0069] The crystallinity of low-density polyethylene can be a function of the amount of branching present on the polymer molecule. The crystallinity of the polymer can generally be over 20%, for example, over 30%, and generally less than 50%, for example, less than 40%. The crystallinity of low-density polyethylene is generally lower than that of high-density polyethylene, which can have crystallinity values ​​ranging from approximately 50% to 75%.

[0061]

[0070] Low-density polyethylene can generally have a narrow or moderate molecular weight distribution. For example, in one embodiment, the molecular weight distribution may be about 3 to about 5, or about 6 to about 12. The molecular weight distribution is defined as the ratio of the weight-average molecular weight to the number-average molecular weight.

[0062]

[0071] The shutdown-reducing additive can also be linear low-density polyethylene. Linear low-density polyethylene polymer chains generally do not have long chain branching. For example, the polymer can be manufactured at a lower temperature than low-density polyethylene. Linear low-density polyethylene can also be polyethylene homopolymer or copolymer of ethylene with a higher alpha-olefin, such as butene, hexene, or octene. In one embodiment, the linear low-density polyethylene is approximately 0.9 g / cm³ 3 For example, approximately 0.91 g / cm³ 3 It can have a density of over 0.93 g / cm³, and is generally about 0.93 g / cm³. 3 Less than, for example, about 0.925 g / cm³ 3 It can have a density of less than [a certain value].

[0063]

[0072] In one embodiment, the shutdown-reducing additive can be metallocene linear low-density polyethylene. Metallocene linear low-density polyethylene is typically tougher than linear low-density polyethylene, with a strength of approximately 0.915 g / cm³. 3 Approximately 0.94 g / cm³ 3 It can have densities between [values]. The polymer is produced using a metallocene catalyst. Metallocene linear low-density polyethylene can be a copolymer of ethylene and butene or hexene. Metallocene linear low-density polyethylene can have a molecular weight distribution or polydispersity index of less than about 3.5, for example less than about 3, for example less than about 2.5.

[0064]

[0073] Shutdown-reducing additives can also consist of polyethylene wax particles. Polyethylene wax generally has a very low molecular weight. For example, the average molecular weight can be less than about 12,000 g / mol, e.g., less than about 8,000 g / mol, e.g., less than about 6,000 g / mol, e.g., less than about 4,000 g / mol, e.g., less than 2,000 g / mol. The number-average molecular weight is generally greater than about 200 g / mol, e.g., greater than about 400 g / mol. Polyethylene wax is typically polyethylene homopolymer, but copolymers also exist. Polyethylene wax can be formed from either low-density polyethylene or high-density polyethylene. In one embodiment, polyethylene wax may have a molecular weight distribution of about 1.5 to 5, e.g., about 1.5 to about 2.5.

[0065]

[0074] When the shutdown-reducing additive contains a polyethylene polymer, the polymer can generally have a melt flow rate of about 0.05 g / 10 min to about 100 g / 10 min (measured under a 2.16 kg load). For example, the melt flow rate can be greater than about 0.1 g / 10 min, e.g., greater than about 0.8 g / 10 min, e.g., greater than about 1 g / 10 min, e.g., greater than about 1.5 g / 10 min, e.g., greater than about 3 g / 10 min, e.g., greater than about 5 g / 10 min, e.g., greater than about 10 g / 10 min, e.g., greater than about 20 g / 10 min. The melt flow rate is generally less than about 70 g / 10 min, e.g., less than about 50 g / 10 min, e.g., less than about 30 g / 10 min, e.g., less than about 20 g / 10 min. In one embodiment, the melt flow rate may be relatively low, such as less than about 10 g / 10 min, for example less than about 8 g / 10 min, for example less than about 6 g / 10 min, for example less than about 4 g / 10 min, for example less than about 3 g / 10 min, for example less than about 2 g / 10 min.

[0066]

[0075] When the shutdown-reducing additive contains a polyethylene polymer, the polyethylene polymer can be in the form of particles. These particles can generally have an average d50 particle size greater than about 100 microns, for example, greater than about 200 microns, for example, greater than about 250 microns, for example, greater than about 300 microns, and generally have an average d50 particle size less than about 1,000 microns, for example, less than about 900 microns, for example less than about 800 microns, for example less than about 600 microns, for example less than about 500 microns. The density of the polyethylene polymer is generally about 0.91 g / cm³. 3 ~Approx. 0.95g / cm 3 It can be somewhere in between, 0.01 g / cm³ 3 This includes all increments.

[0067]

[0076] In addition to a variety of polyethylene polymers, shutdown-reducing additives may also include fatty acid derivatives, such as hydrogenated fatty acids, or fatty acid dimers. Hydrogenated fatty acids are fatty acids in which most of the double bonds have been converted to single bonds. Hydrogenated fatty acids can be formed from fatty acids having carbon chain lengths of more than about 12 carbon atoms, e.g., more than about 16 carbon atoms, e.g., more than about 18 carbon atoms, e.g., more than about 20 carbon atoms, e.g., more than 24 carbon atoms, and generally from fatty acids having carbon chain lengths of less than about 52 carbon atoms, e.g., less than about 48 carbon atoms, e.g., less than about 38 carbon atoms.

[0068]

[0077] Dimers of fatty acids, or dimerized fatty acids, are prepared by dimerizing unsaturated fatty acids obtained from tall oils. Dimerized fatty acids can be formed from fatty acids having the carbon chain lengths described above with respect to hydrogenated fatty acids.

[0069]

[0078] In yet another embodiment, the shutdown-reducing additive may include elastomer particles. Examples of thermoplastic elastomers include styrene block copolymers, olefin elastomers, polyester elastomers, polyamide elastomers, and polyurethane elastomers. Examples of styrene block copolymers include styrene-ethylene-ethylene-propylene-styrene polymers, styrene-ethylene-butylene-styrene polymers, and styrene-butadiene-styrene polymers.

[0070]

[0079] In one embodiment, elastomer particles are made from a polyurethane elastomer. The thermoplastic polyurethane elastomer may, for example, have a soft segment of a long-chain diol, a hard segment derived from a diisocyanate, and a chain extender. In one embodiment, the polyurethane elastomer is of the polyester type, prepared by reacting a long-chain diol with a diisocyanate to produce a polyurethane prepolymer having isocyanate end groups, and then chain-extending the prepolymer with a diol chain extender. Typical long-chain diols are polyester diols, such as polybutylene diol adipate, polyethylene diol adipate, and poly(ε-caprolactone)diol; and polyether diols, such as poly(tetramethylene ether) glycol, polypropylene oxide glycol, and polyethylene oxide glycol. Suitable diisocyanates include 4,4'-methylenebis(phenyl isocyanate), 2,4-toluene diisocyanate, 1,6-hexamethylene diisocyanate, and 4,4'-methylenebis-(cyclooxyl isocyanate). Suitable chain extenders are C2-C6 aliphatic diols, such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol. One example of a thermoplastic polyurethane is essentially characterized as poly(adipic acid-co-butylene glycol-co-diphenylmethane diisocyanate).

[0071]

[0080] Elastomer particles can also be made from copolyester elastomers. In one embodiment, the copolyester elastomer may contain ester and ether bonds. For example, the copolyester elastomer may have an alternating structure defined by a large number of randomly repeating long-chain and short-chain ester units linked together by head-tail chains via ester bonds.

[0072]

[0081] The long-chain ester unit is given by the formula:

[0073] [ka]

[0074] Represented by, On the other hand, the short-chain ester unit is given by formula:

[0075] [ka]

[0076] Represented by, During the ceremony, - G is a divalent group remaining after removing the terminal hydroxyl group from a polyol having a molecular weight between approximately 250 and 6000. - R is a divalent group remaining after removing the carboxyl group from a dicarboxylic acid having a molecular weight of less than approximately 300. - D is the divalent group remaining after removing the hydroxyl group from a diol with a molecular weight of less than approximately 250.

[0077]

[0082] For G and D groups, the expression "divalent group" refers to a group having two hydroxyl reaction centers, one located at the head of the molecule and the other at the tail. For R groups, the expression "divalent group" refers to a group having two carboxyl reaction centers, one located at the head of the molecule and the other at the tail.

[0078]

[0083] Structurally, the R group is a group that confers polyester bonds. More specifically, when the R group has an aromatic moiety, they give the copolyester crystalline properties.

[0084] The G group, when combined with the R group, imparts elastomeric properties to the copolyester.

[0079]

[0085] In combination with R groups, D groups impart rigid properties to copolyesters.

[0086] The above alternating structure may contain 5% to 15% by weight of short-chain ester units and 70% to 80% by weight of long-chain ester units.

[0080]

[0087] In one embodiment, an alternating structure thermoplastic copolyester elastomer can be obtained according to the following general reaction scheme: - Esterification / transesterification of esters of one or more carboxylic acids, one or more dicarboxylic acids, and / or one or more dimer or trimer carboxylic acids with diols and diol polyglycols. - Subsequent polycondensation of esterification / transesterification products.

[0081]

[0088] The molecular weight of copolyester elastomers can vary depending on the specific application. In one embodiment, for example, the molecular weight of the copolyester elastomer is greater than about 20,000 g / mol, for example, greater than about 25,000 g / mol, for example, greater than about 28,000 g / mol, for example, greater than about 30,000 g / mol, for example, greater than about 35,000 g / mol, for example, greater than about 40,000 g / mol, for example, greater than about 45,000 g / mol, for example, greater than about 50,000 g / mol. The molecular weight of polyester elastomers is generally less than about 200,000 g / mol, for example, less than about 100,000 g / mol.

[0082]

[0089] In yet another embodiment, the shutdown-reducing additive may be a plastomer. A plastomer is a polymer material that combines the qualities of an elastomer with the qualities of a thermoplastic. In one embodiment, the polyolefin plastomer is used comprising an alpha-olefin copolymer, more particularly an alpha-olefin polyethylene copolymer. Preferred alpha-olefins may be linear or branched (e.g., one or more C1-C3 alkyl branching or aryl groups). Specific examples include ethylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene having one or more methyl, ethyl, or propyl substituents; 1-hexene having one or more methyl, ethyl, or propyl substituents; 1-heptene having one or more methyl, ethyl, or propyl substituents; 1-octene having one or more methyl, ethyl, or propyl substituents; 1-nonene having one or more methyl, ethyl, or propyl substituents; 1-decene substituted with ethyl, methyl, or dimethyl; 1-dodecene; and styrene. Particularly desirable alpha-olefin comonomers are ethylene, 1-butene, 1-hexene, and 1-octene. The ethylene content of such copolymers may range from about 60 mol% to about 99.5 wt.%, about 80 mol% to about 99 mol% in some embodiments, and about 85 mol% to about 98 mol% in some embodiments. The alpha-olefin content may similarly range from about 0.5 mol% to about 40 mol%, about 1 mol% to about 20 mol% in some embodiments, and about 2 mol% to about 15 mol% in some embodiments. The distribution of alpha-olefin comonomers is typically random and uniform among the fractions of different molecular weights that form the ethylene copolymer.

[0083]

[0090] The density of the plastomer may generally be less than about 0.95 g / cc, for example less than about 0.91 g / cc. The density of the polyolefin may generally be greater than about 0.8 g / cc, for example greater than about 0.85 g / cc, for example greater than about 0.88 g / cc. In one embodiment, the plastomer may have a glass transition temperature of less than about 35°C, for example less than about 25°C.

[0084]

[0091] As described above, the shutdown-reducing additive is in the form of particles combined with high-density polyethylene particles. Generally, the shutdown-reducing additive particles have a median volume particle size of less than about 800 microns, e.g., less than about 600 microns, e.g., less than about 400 microns, e.g., less than 200 microns. The median particle size of the shutdown-reducing additive is generally greater than about 10 microns, e.g., greater than about 20 microns, e.g., greater than about 50 microns, e.g., greater than 70 microns. In one embodiment, the shutdown-reducing additive particles can be selected, crushed, or milled so that their particle size substantially matches that of the high-density polyethylene particles. For example, the median particle size of the shutdown-reducing additive can be within (+ or -) about 20%, e.g., about 10%, of the median particle size of the high-density polyethylene particles.

[0085]

[0092] Shutdown-reducing additives generally have a melt flow rate of approximately 0.01 g / 10 min to approximately 110 g / 10 min, for example, approximately 0.03 g / 10 min to approximately 70 g / 10 min, for example, approximately 0.05 g / 10 min to approximately 50 g / 10 min. The melt flow rate can be measured using ISO Test 1133 at a temperature of 190 °C under a load of 2.16 kg. More specifically, the melt flow rate of the shutdown-reducing additive can be greater than approximately 2 g / 10 min, for example, greater than approximately 7 g / 10 min, for example, greater than approximately 10 g / 10 min, and generally less than approximately 60 g / 10 min, for example, less than approximately 40 g / 10 min, for example, less than approximately 30 g / 10 min, for example, less than approximately 25 g / 10 min, for example, less than approximately 20 g / 10 min.

[0086]

[0093] In one embodiment, the shutdown-reducing additive (any of the shutdown-reducing additives identified above) may generally have a melting point of less than about 130°C, for example less than about 129°C, for example about 128°C. The melting point is generally greater than about 105°C, for example greater than about 115°C.

[0087]

[0094] Shutdown-reducing additives are generally present in polymer compositions in amounts of 2% to about 40% by weight in combination with high-density polyethylene particles and plasticizers. For example, shutdown-reducing additives can be present in polymer compositions in amounts greater than about 2% by weight, for example, greater than about 4% by weight, for example, greater than about 8% by weight, for example, greater than about 10% by weight, for example, greater than about 12% by weight, for example, greater than about 15% by weight, for example, greater than about 18% by weight, for example, greater than about 20% by weight, for example, greater than about 22% by weight, and generally less than about 40% by weight, for example, less than about 35% by weight, for example, greater than about 30% by weight, for example, less than about 20% by weight, for example, less than about 15% by weight.

[0088]

[0095] Once the article is formed from the polymer composition through gel extrusion as described above, most, if not all, of the plasticizers can be removed. Therefore, the shutdown-reducing additives can be present in the final product, for example in the porous membrane, in amounts of more than about 3% by weight, for example more than about 5% by weight, for example more than about 7% by weight, for example more than about 8% by weight, for example more than about 10% by weight, for example more than about 12% by weight, and generally in amounts of less than about 30% by weight, for example less than about 25% by weight, for example less than about 20% by weight, for example less than about 15% by weight, for example less than about 10% by weight.

[0089]

[0096] The effect of shutdown-reducing additives on the shutdown temperature of polymer articles made from polymer compositions can depend on a variety of factors. Generally, one or more shutdown-reducing additives are incorporated into a polymer composition such that the shutdown temperature of the polymer composition is reduced by at least 1.8°C, e.g., at least 2.2°C, e.g., at least 2.5°C, e.g., at least 2.8°C, e.g., at least 3°C, e.g., at least 3.3°C, e.g., at least 3.5°C, e.g., at least 3.8°C, e.g., at least 4°C, compared to articles made from polymer compositions in which the shutdown-reducing additives are replaced by a further amount of high-density polyethylene particles. In one embodiment, the shutdown temperature of the polymer composition is reduced by at least 5°C, e.g., at least 6°C, e.g., at least 7°C.

[0090]

[0097] The amount by which the shutdown temperature is reduced by the use of additives is somewhat more important than the final or ultimate shutdown temperature of the polymer composition. For example, the additives of this disclosure enable the use of polyethylene polymers with higher shutdown temperatures and better performance. The additives of this disclosure can be combined with these polymers, for example, to keep the shutdown temperature within the levels previously used through the use of inferior polyethylene polymers. However, generally, the shutdown temperature of articles made from polymer compositions can be 133.7°C or lower, e.g., 133.4°C or lower, e.g., 132.9°C or lower, e.g., 132.5°C or lower, e.g., 132.3°C or lower, e.g., 132°C or lower, e.g., 131.7°C or lower, e.g., 131.5°C or lower, e.g., 131.3°C or lower, e.g., 131°C or lower. The shutdown temperature can be 130°C or lower, e.g., 129°C or lower. The shutdown temperature is generally above about 120°C, e.g., above about 125°C. The above shutdown temperatures are based on measurements of polymer articles using impedance testing.

[0091]

[0098] In addition to high-density polyethylene particles and at least one shutdown-reducing additive, the polymer composition further contains a plasticizer. Generally, any suitable plasticizer can be combined with other components, insofar as the plasticizer is capable of forming a gel-like material suitable for gel spinning or extrusion.

[0092]

[0099] The plasticizer may include, for example, hydrocarbon oils, alcohols, ethers, esters, such as diesters, or mixtures thereof. Suitable plasticizers include mineral oils, paraffinic oils, and decalin. Other plasticizers include xylene, dioctyl phthalate, dibutyl phthalate, stearyl alcohol, oleyl alcohol, decyl alcohol, nonyl alcohol, diphenyl ether, n-decane, n-dodecane, octane, nonane, kerosene, toluene, naphthalene, and tetralin. In one embodiment, the plasticizer may also include halogenated hydrocarbons, such as monochlorobenzene. Cycloalkanes and cycloalkenes may also be used, such as camphene, methane, dipentene, methylcyclopentanediene, tricyclodecane, and 1,2,4,5-tetramethyl-1,4-cyclohexadiene. The plasticizer may also include mixtures and combinations of any of the above.

[0093] [000100] Plasticizers are generally present in compositions used to form polymer articles in amounts greater than about 50% by weight, for example, greater than about 55% by weight, for example, greater than about 60% by weight, for example, greater than about 65% by weight, for example, greater than about 70% by weight, for example, greater than about 75% by weight, for example, greater than about 80% by weight, for example, greater than about 85% by weight, for example, greater than about 90% by weight, for example, greater than about 95% by weight, for example, greater than about 98% by weight. In fact, plasticizers can be present in amounts up to about 99.5% by weight.

[0094] [000101] High-density polyethylene particles and shutdown-reducing additives are blended with plasticizers to form a homogeneous gel-like material. [000102] To form polymer articles according to the present disclosure, high-density polyethylene particles are combined with a shutdown-reducing additive and a plasticizer and extruded through a die of a desired shape. In one embodiment, the composition may be heated in the extruder. For example, the plasticizer may be combined with the particle mixture and supplied into the extruder. According to the present disclosure, the plasticizer and particle mixture form a homogeneous gel-like material, which is then used to cause the extruder to form polymer articles ranging from those with few impurities to those with no impurities at all.

[0095] [000103] In one embodiment, an elongated article is formed during a gel spinning or extrusion process. The polymer article may be in the form of, for example, a fiber or a film, such as a membrane.

[0096] [000104] During the process, at least a portion of the plasticizer is removed from the final product. Plasticizer removal can occur by evaporation when relatively volatile plasticizers are used. Otherwise, an extractant can be used to remove the plasticizer. The extractant may include, for example, a hydrocarbon solvent. One example of an extractant is dichloromethane. Other extractants include acetone, chloroform, alkanes, hexene, heptene, alcohols, or mixtures thereof.

[0097] [000105] If desired, the resulting polymer article may be stretched at a temperature below the melting point of the polymer mixture to enhance its strength and elasticity. A suitable temperature for stretching is approximately within the range of ambient temperature to about 155°C. The stretch ratio can generally be greater than about 4, for example greater than about 6, for example greater than about 8, for example greater than about 10, for example greater than about 15, for example greater than about 20, for example greater than about 25, for example greater than about 30. In certain embodiments, the stretch ratio can be greater than about 50, for example greater than about 100, for example greater than about 110, for example greater than about 120, for example greater than about 130, for example greater than about 140, for example greater than about 150. The stretch ratio is generally less than about 1,000, for example less than about 800, for example less than about 600, for example less than about 400. In one embodiment, a lower stretch ratio is used, for example about 4 to about 10. The polymer article may be stretched uniaxially or biaxially.

[0098] [000106] Polymer articles made in accordance with this disclosure have a number of uses and applications. For example, in one embodiment, a method for producing a membrane is used. The membrane may be used, for example, as a battery separator. Alternatively, the membrane may be used as a microfilter. When producing fibers, the fibers may be used to produce nonwoven fabrics, ropes, nets, etc. In one embodiment, the fibers may be used as a filler material in bulletproof clothing.

[0099] [000107] Referring to Figure 2, one embodiment of a lithium-ion battery 10 to be manufactured according to the present disclosure is shown. The battery 10 comprises an anode 12 and a cathode 14. The anode 12 may be made from lithium metal, for example. The cathode 14, on the other hand, may be made from sulfur or from an inserted lithium metal oxide. According to the present disclosure, the battery 10 further comprises a porous membrane 16, or a separator located between the anode 12 and the cathode 14. The porous membrane 16 minimizes electrical short circuits between the two electrodes while allowing the passage of ions, such as lithium ions. As shown in Figure 2, in one embodiment, the porous membrane 16 is a single-layer polymer membrane and does not include a multilayer structure. In one embodiment, the single-layer polymer membrane may also include a coating. The coating may be an inorganic coating made from aluminum oxide or titanium oxide, for example. Alternatively, the single-layer polymer membrane may also include a polymer coating. The coating can provide enhanced heat resistance.

[0100] [000108] Polymer compositions and polymer articles prepared in accordance with this disclosure may contain a variety of other additives, such as heat stabilizers, light stabilizers, UV absorbers, acid scavengers, flame retardants, lubricants, colorants, and the like.

[0101] [000109] In one embodiment, a heat stabilizer may be present in the composition. Examples of heat stabilizers include, but are not limited to, phosphites, amine antioxidants, phenol antioxidants, or any combination thereof.

[0102] [000110] In one embodiment, an antioxidant may be present in the composition. The antioxidant may include, but is not limited to, a secondary aromatic amine, a benzofuranone, a sterically hindered phenol, or any combination thereof.

[0103] [000111] In one embodiment, a light stabilizer may be present in the composition. Examples of light stabilizers include, but are not limited to, 2-(2'-hydroxyphenyl)-benzotriazole, 2-hydroxy-4-alkoxybenzophenone, nickel-containing light stabilizers, 3,5-di-tert-butyl-4-hydrobenzoate, sterically hindered amines (HALS), or any combination thereof.

[0104] [000112] In one embodiment, a UV absorber may be present in the composition in place of or in addition to a light stabilizer. Examples of UV absorbers include, but are not limited to, benzotriazoles, benzoates, or combinations thereof or any combination thereof.

[0105] [000113] In one embodiment, a halogenated flame retardant may be present in the composition. Examples of halogenated flame retardants include, but are not limited to, tetrabromobisphenol A (TBBA), tetrabromophthalic anhydride, dedecachloropentacyclooctadecadiene (decloran), hexabromocyclodedecane, chlorinated paraffin, or any combination thereof.

[0106] [000114] In one embodiment, a non-halogenated flame retardant may be present in the composition. Examples of non-halogenated flame retardants include, but are not limited to, resorcinol diphosphate tetraphenyl ester (RDP), ammonium polyphosphate (APP), phosphinic acid derivatives, triaryl phosphate, trichloropropyl phosphate (TCPP), magnesium hydroxide, aluminum trihydroxyoxide, and antimony trioxide.

[0107] [000115] In one embodiment, a lubricant may be present in the composition. The lubricant may be, but is not limited to, silicone oil, wax, molybdenum disulfide, or any combination thereof.

[0108] [000116] In one embodiment, a colorant may be present in the composition. Examples of colorants include, but are not limited to, inorganic and organic-based color pigments. [000117] In one embodiment, an acid scavenger may be present in the polymer composition. The acid scavenger may include, for example, an alkali metal salt or an alkaline earth metal salt. The salt may include a salt of a fatty acid, such as stearate. Other acid scavengers include carbonates, oxides, or hydroxides. Specific acid scavengers that may be incorporated into the polymer composition include metal stearate, such as calcium stearate. Further other acid scavengers include zinc oxide, calcium carbonate, magnesium oxide, and mixtures thereof.

[0109] [000118] These additives may be used individually or in any combination thereof. Generally, each additive may be present in the polymer composition or the resulting polymer article in an amount of at least about 0.05 wt.%, e.g., at least about 0.1 wt.%, e.g., at least about 0.25 wt.%, e.g., at least about 0.5 wt.%, e.g., at least about 1 wt.%, and generally in an amount of less than about 20 wt.%, e.g., less than about 10 wt.%, e.g., less than about 5 wt.%, e.g., less than about 4 wt.%, e.g., less than 2 wt.%. The sum of all wt.% of the components that are used in the polymer composition and article, including any additives if present, is 100 wt.%.

[0110] [000119] This disclosure may be better understood by reference to the following examples. The following examples are given below by illustration and not by limitation. The following experiments were performed to demonstrate some of the benefits and advantages of the present invention. [Examples]

[0111] Example 1 [000120] In order to demonstrate that the resin prepared in accordance with this disclosure produces a film with a lower shutdown (SD) temperature compared to the unmodified resin, the following examples were provided.

[0112] [000121] Various resin compositions were formulated by incorporating a high-density polyethylene base resin containing various shutdown-reducing additives. The additives were blended with high-density polyethylene of two different molecular weights in various weight ratios using a tumble blender. The resin compositions were prepared into films by conventional methods such as gel extrusion, biaxial stretching, and solvent extraction.

[0113] [000122] In this embodiment, the shutdown-reducing additive used was low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE). In other embodiments, the shutdown-reducing additive was a plastomer. The plastomer was an alpha-olefin random copolymer. More specifically, the plastomer used was an octene-ethylene random copolymer. The shutdown temperature of the modified composition containing the additive was compared with the shutdown temperature of the unmodified resin without the additive. The shutdown temperature of the obtained film was determined using three independent methods: directly by impedance spectroscopy, indirectly via the softening point by dynamic thermomechanical analysis (TMA), and indirectly via the melting point by differential scanning calorimetry (DSC). All tests were performed on stretched films.

[0114] [000123] In the following sample compositions, plasticizers were present in an amount of 70% by weight and were almost completely removed during film formation. The amounts of shutdown-reducing additives in the extruded compositions and in the final product are shown in the table below. High-density polyethylene polymer constituted the remainder of the compositions and films. The following results were obtained.

[0115] [Table 1]

[0116] [000124]Figure 1 is a graphical representation of the impedance tests performed in Examples 1 and 3. As shown, Example 3, which contains linear low-density polyethylene, dramatically reduced the shutdown temperature. The shutdown temperature was reduced without affecting other properties of the porous membrane.

[0117] Example 2 [000125] The procedure of Example 1 was repeated using various different shutdown-reducing additives in different amounts. All of the shutdown-reducing additives were polyethylene polymers, such as linear low-density polyethylene polymers, high-density polyethylene polymers, and low-density polyethylene polymers. More specifically, different samples were given the following shutdown-reducing additives.

[0118] [Table 2]

[0119] [000126] Sample numbers 38 and 39: Combinations of sample number 22 and sample number 28 in a 50:50 weight ratio [000127] Sample numbers 40 and 41: Combinations of sample number 30 and sample number 34 in a 50:50 weight ratio [000128] The above shutdown-reducing additive was combined with a base polyethylene resin having a molecular weight of 1,700,000 g / mol according to the procedure described in Example 1. A film was formed and various properties were measured. The following results were obtained.

[0120] [Table 3]

[0121] [000129] These and other modifications and variations of the present invention can be practiced by those skilled in the art without departing from the spirit and scope of the invention as set out in more detail in the appended claims. In addition, it should be understood that the various embodiments are interchangeable in whole or in part. Furthermore, those skilled in the art will recognize that the prior description is by example only and is not intended to limit the invention as described further in such appended claims. The claims as submitted at the time of filing are shown below. [Claim 1] A polymer composition for manufacturing gel extruded articles, Plasticizers and High-density polyethylene particles and Shutdown-reducing additives and The shutdown-reducing additive comprises particles that, when combined with the high-density polyethylene particles and the plasticizer, reduce the shutdown temperature of a film made from the polymer composition, and the shutdown-reducing additive comprises a second high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, medium-density polyethylene, polyethylene wax, hydrogenated fatty acids, fatty acid amides, fatty acid dimers, plastomers, elastomers, or mixtures thereof. Polymer composition. [Claim 2] A polymer composition for manufacturing gel extruded articles, Plasticizers and High-density polyethylene particles and Shutdown-reducing additives and The shutdown-reducing additive comprises particles combined with the high-density polyethylene particles and the plasticizer, The polymer composition, when formed into a film, has a shutdown temperature at least 1.4°C lower than that of a polymer composition in which the shutdown-reducing additive is replaced by a further amount of the high-density polyethylene particles. Polymer composition. [Claim 3] The polymer composition according to claim 2, wherein the shutdown temperature is at least 1.8°C lower, for example at least 2.2°C lower, for example at least 2.5°C lower, compared to a polymer composition in which the shutdown-reducing additive is replaced by a further amount of the high-density polyethylene particles. [Claim 4] The polymer composition according to claim 2, wherein the shutdown temperature is at least 3°C ​​lower, for example at least 4°C lower, for example at least 5°C lower, for example at least 6°C lower, compared to a polymer composition in which the shutdown-reducing additive is replaced by a further amount of the high-density polyethylene particles. [Claim 5] The polymer composition according to claim 2, wherein the shutdown-reducing additive comprises a second high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, medium-density polyethylene, polyethylene wax, hydrogenated fatty acid, fatty acid amide, fatty acid dimer, plastomer, elastomer, or a mixture thereof. [Claim 6] The polymer composition according to any one of claims 1 to 5, wherein the shutdown-reducing additive comprises a polyethylene polymer having an MFR of about 0.05 g / 10 min to about 70 g / 10 min, for example, about 1 g / 10 min to about 20 g / 10 min. [Claim 7] The polymer composition according to any one of claims 1 to 6, wherein the shutdown-reducing additive is present in the composition in an amount of about 0.5% to about 15% by weight, for example, in an amount of about 2% to about 8% by weight. [Claim 8] Claim 1, wherein the high-density polyethylene particles have a volume median particle size of less than approximately 150 microns, and the shutdown-reducing additive has a volume median particle size of less than approximately 800 microns. A polymer composition according to any one of items to 7. [Claim 9] The polymer composition according to any one of claims 1 to 8, wherein the high-density polyethylene particles are present in the composition in an amount of up to about 50% by weight. [Claim 10] The polymer composition according to any one of claims 1 to 9, wherein the plasticizer comprises mineral oil, paraffinic oil, hydrocarbon, alcohol, ether, ester, or a mixture thereof. [Claim 11] The polymer composition according to any one of claims 1 to 10, wherein the high-density polyethylene has a molecular weight of more than about 600,000 g / mol, for example more than about 1,000,000 g / mol, for example more than about 1,500,000 g / mol, and a molecular weight of less than about 4,000,000 g / mol, for example less than about 3,500,000 g / mol. [Claim 12] The polymer composition according to any one of claims 1 to 11, wherein the high-density polyethylene is Ziegler-Natta catalyst high molecular weight polyethylene. [Claim 13] The polymer composition according to any one of claims 1 to 12, wherein the plasticizer comprises decalin, paraffin oil, white oil, mineral oil, xylene, dioctyl phthalate, dibutyl phthalate, stearyl alcohol, oleyl alcohol, decyl alcohol, nonyl alcohol, diphenyl ether, n-decane, n-dodecane, octane, nonane, kerosene, toluene, naphthalene, tetralin, monochlorobenzene, camphene, methane, dipentene, methylcyclopentanediene, tricyclodecane, 1,2,4,5-tetramethyl-1,4-cyclohexadiene, or a mixture thereof. [Claim 14] A method for manufacturing polymer articles, A step of forming a gel-like composition from a polymer composition according to any one of claims 1 to 13, The steps include: extruding the gel-like composition through a die to form a polymer article; Includes, The polymer article includes a film, method. [Claim 15] The method according to claim 14, further comprising the step of removing at least a portion of the plasticizer from the polymer article. [Claim 16] The method according to claim 14 or 15, wherein an extraction solvent is added to the polymer composition during the method to facilitate the removal of the plasticizer from the polymer article. [Claim 17] The method according to claim 16, wherein the extraction solvent comprises dichloromethane, acetone, chloroform, hexene, heptane, alcohol, or a mixture thereof. [Claim 18] A porous membrane comprising high-density polyethylene combined with a shutdown-reducing additive, wherein the shutdown-reducing additive comprises a second high-density polyethylene, low-density polyethylene, medium-density polyethylene, linear low-density polyethylene, metallocene catalyst linear low-density polyethylene, polyethylene wax, hydrogenated fatty acid, fatty acid amide, fatty acid dimer, plastomer, elastomer, or a mixture thereof, wherein the shutdown-reducing additive is present in the porous membrane in an amount sufficient to reduce the shutdown temperature of the membrane by at least 2°C when measured in accordance with an impedance test. [Claim 19] The high-density polyethylene is present in the film in an amount of approximately 60% to approximately 98% by weight, The porous membrane according to claim 18, wherein the shutdown-reducing additive is present in the membrane in an amount of about 2% to about 40% by weight, for example, about 3% to about 10% by weight. [Claim 20] A battery comprising an anode, a cathode, and a separator membrane disposed between the anode and the cathode, wherein the separator membrane includes the porous membrane described in claim 18 or 19. [Claim 21] The battery according to claim 20, wherein the separator film is a single-layer polymer film that may optionally include a coating. [Claim 22] The battery according to claim 21, wherein the single-layer polymer film includes a coating, and the coating includes an inorganic coating or a polymer coating. [Claim 23] The porous membrane according to claim 18, wherein the shutdown-reducing additive comprises a plastomer, and the plastomer comprises a random copolymer of octene and ethylene. [Claim 24] The porous membrane according to claim 18, wherein the shutdown-reducing additive comprises linear low-density polyethylene or low-density polyethylene.

Claims

1. A polymer composition for manufacturing gel extruded articles, A plasticizer present in the polymer composition in an amount exceeding 50% by weight, High-density polyethylene particles, wherein the high-density polyethylene particles However, 0.93 g / cm³ ３ The above densities and conform to DIN EN ISO Test 1628. Based on the measured viscosity number, the value was calculated using Margoly's equation to be 500,000 g / mo. The high-density polyethylene particles having a number-average molecular weight exceeding l, Shutdown-reducing additives and The shutdown-reducing additive includes the high-density polyethylene particles and the When combined with a plasticizer, the shutdown temperature of the film made from the polymer composition is The shutdown-reducing additive contains particles that reduce the shutdown, and the shutdown-reducing additive is low-density polyethylene, linear Low-density polyethylene, metallocene catalyst linear low-density polyethylene, medium-density polyethylene, The shutdown comprises ethylene wax, plastomer, or a mixture thereof. The degrading additive was found to be 2.16 K at 190°C in accordance with ISO Test 1133. It has an MFR of 0.1 g / 10 min to 70 g / 10 min as measured under a load of g, The plastomer has a density of less than 0.91 g / cc. Polymer composition.

2. A polymer composition for manufacturing gel extruded articles, A plasticizer present in the polymer composition in an amount exceeding 50% by weight, High-density polyethylene particles, wherein the high-density polyethylene particles However, 0.93 g / cm³ ３ The above densities and conform to DIN EN ISO Test 1628. Based on the measured viscosity number, the value was calculated using Margoly's equation to be 500,000 g / mo. The high-density polyethylene particles having a number-average molecular weight exceeding l, Shutdown-reducing additives and The shutdown-reducing additive includes the high-density polyethylene particles and the The particles are combined with a plasticizer, and the shutdown-reducing additive is ISO Test 1 0.1 g measured in accordance with 133, under a load of 2.16 kg at a temperature of 190°C. Having an MFR of 10 to 70 g / 10 minutes, The shutdown-reducing additive is low-density polyethylene, linear low-density polyethylene, Metallocene catalyst linear low-density polyethylene, medium-density polyethylene, polyethylene wax, comprising a plastomer or a mixture thereof, wherein the plastomer is 0.91 g / Having a density of less than cc, When the polymer composition is formed into a film, the shutdown-reducing additive is Compared to a polymer composition replaced by a certain amount of the high-density polyethylene particles And, having a shutdown temperature at least 1.4°C lower, Polymer composition.

3. The shutdown temperature is further reduced by the shutdown-reducing additive in a greater amount of the high density Compared to polymer compositions replaced with polyethylene particles, at least 1. 8°C lower, for example at least 2.2°C lower, for example at least 2.5°C lower, according to claim 2 The polymer composition described.

4. The shutdown temperature is further reduced by the shutdown-reducing additive in a greater amount of the high density Compared to polymer compositions replaced with polyethylene particles, at least 3°C Lower, for example, at least 4°C lower, for example, at least 5°C lower, for example, at least 6°C lower i. The polymer composition according to claim 2.

5. The shutdown-reducing additive is used in accordance with ISO Test 1133, at 190°C. MF measured at a temperature with a load of 2.16 kg: 1 g / 10 min to 20 g / 10 min A polyethylene polymer having R, according to any one of claims 1 to 4 - Composition.

6. The shutdown-reducing additive is present in an amount of 0.5% to 15% by weight, for example, 2 by weight. The composition contains the portion according to any one of claims 1 to 5, in an amount of % to 8% by weight. Limer composition.

7. The high-density polyethylene was measured using the laser diffraction method according to ISO 13320. The particles have a volume-medium particle size of less than 150 microns, and the shutdown-reducing additive is , having a volume median particle size of less than 800 microns, according to any one of claims 1 to 6 Polymer composition.

8. The claim states that the high-density polyethylene particles are present in the composition in an amount of less than 45% by weight. A polymer composition according to any one of items 1 to 7.

9. The aforementioned plasticizer is mineral oil, paraffinic oil, hydrocarbon, alcohol, ether, ester, A polymer composition according to any one of claims 1 to 8, comprising a mixture thereof.

10. The high-density polyethylene was measured in accordance with DIN EN ISO Test 1628. Using Margolies' equation to calculate from the viscosity number, it is calculated to be over 600,000 g / mol, for example. For example, if it is more than 1,000,000 g / mol, for instance, more than 1,500,000 g / mol, Molecules with a concentration of less than 4,000,000 g / mol, for example, less than 3,500,000 g / mol. A polymer composition according to any one of claims 1 to 9, having a certain amount.

11. The polymer composition according to any one of claims 1 to 10, wherein the high-density polyethylene is Ziegler-Natta catalyst high molecular weight polyethylene.

12. The aforementioned plasticizers include decalin, paraffin oil, white oil, mineral oil, xylene, and dioctyl phthalate. Dibutyl phthalate, stearyl alcohol, oleyl alcohol, decyl alcohol , nonyl alcohol, diphenyl ether, n-decane, n-dodecane, octane, nona N, kerosene, toluene, naphthalene, tetralin, monochlorobenzene, camphene, Methane, dipentene, methylcyclopentanediene, tricyclodecane, 1, 2, 4, 5 Claim 1 comprises -tetramethyl-1,4-cyclohexadiene or a mixture thereof. A polymer composition according to any one of claims from 11 to 11.

13. A method for manufacturing polymer articles, A polymer composition according to any one of claims 1 to 12 is formed into a gel-like composition. Step and, The steps include: extruding the gel-like composition through a die to form a polymer article; Includes, The polymer article includes a film, method.

14. The further step includes removing at least a portion of the plasticizer from the polymer article. The method according to claim 13.

15. The extraction solvent is added to the polymer composition during the above method to remove the pre-extraction solvent from the polymer article. The method according to claim 13 or 14, which facilitates the removal of the plasticizer.

16. The extraction solvent is dichloromethane, acetone, chloroform, hexene, heptane, and The method according to claim 15, comprising licorice or a mixture thereof.

17. A porous membrane containing high-density polyethylene combined with a shutdown-reducing additive. Furthermore, the high-density polyethylene is present in the porous membrane in an amount exceeding 70% by weight, The density of polyethylene is 0.93 g / cm³. ３ The above densities, and DIN EN ISO Te 500 is calculated using Margolyes' equation from the viscosity number measured according to ST1628. Having a number average molecular weight exceeding 000 g / mol, the shutdown-reducing additive is Low-density polyethylene, medium-density polyethylene, linear low-density polyethylene, metallocene catalyst Chain low-density polyethylene, polyethylene wax, plastomer, or mixtures thereof. Including, The porous membrane was measured in accordance with an impedance test, and the shutdown reduction rate was found to be lower. A polymer composition in which the additive is replaced by a further amount of high-density polyethylene particles. The shutdown temperature is set to be at least 1.4°C lower than the shutdown temperature. The shutdown-reducing additive is present in the porous membrane, and the shutdown temperature of the porous membrane It is present in an amount sufficient to lower the degree, The shutdown-reducing additive is determined in accordance with ISO Test 1133 at 190°C. Measuring with a 2.16 kg load at temperature, the M2 reading is 0.1 g / 10 min to 70 g / 10 min. It has FR, The plastomer has a density of less than 0.91 g / cc. Porous membrane.

18. The high-density polyethylene is present in the film in an amount of 60% to 98% by weight, and the The amount of the shutdown-reducing additive is 2% to 40% by weight, for example, 3% to 10% by weight. The porous membrane according to claim 17, wherein the porous membrane is present in the aforementioned membrane.

19. Anode, cathode, and separator positioned between the anode and the cathode A battery comprising a separator film, wherein the separator film is as described in claim 17 or 18. A battery containing a porous membrane.

20. The separator film is a single-layer polymer film that may optionally include a coating. The battery according to claim 19.

21. The single-layer polymer film includes a coating, and the coating is an inorganic coating. The battery according to claim 20, comprising a polymer coating or a similar coating.

22. The shutdown-reducing additive includes a plastomer, and the plastomer is oc A porous membrane according to claim 17, comprising a random copolymer of tene and ethylene.

23. The shutdown-reducing additive is linear low-density polyethylene or low-density polyethylene A porous membrane according to claim 17, comprising n.

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