Polymer film produced by dry process and product using the same

Abstract

To provide a microporous membrane having improved performance such as reduced MD cracking and a method for producing the same.SOLUTION: The present invention provides a novel or improved impregnating base film, an impregnated base film, a product incorporating the impregnated base film, and / or related methods as disclosed, claimed, or described herein.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] According to at least selected embodiments, the present application or invention relates to new or improved substrate films for impregnation, impregnated substrate films, products incorporating impregnated substrate films, and / or related methods as shown, claimed, or described herein. According to at least certain embodiments, the present application or invention relates to or provides improved substrate films for polymer impregnation to make improved impregnated membranes for use in battery separators, such as for secondary lithium ion batteries, and other applications such as textiles, filtration, humidity control, and the like, and related methods for making and using such substrate films, impregnated substrate films, battery separators, and / or the like. In at least certain embodiments, the present application or invention relates to new and / or improved microporous polyolefin membranes that can be used or can be used as separators for batteries, lithium batteries, lead acid batteries, capacitors, fuel cells, and new and / or improved methods that can be used to form the membranes and / or separators. [Background technology]

[0002] Microporous polymeric membranes are known and can be made by a variety of processes, which may include materials that affect the physical properties of the membrane. See, for example, Kesting, Robert E., Synthetic Polymeric Membranes, A Structural Perspective, Second Edition, John Wiley & Sons, New York, NY, (1985). Three different known processes for making microporous polymeric membranes include: dry stretching (also known as the CELGARD process), wet process, and particle stretching.

[0003] Dry stretching (CELGARD or dry process) refers to a process in which pores are formed as a result of stretching extruded non-porous semi-crystalline polymer precursors in the machine direction (MD stretching) to form pores. See, for example, Kesting, Ibid. pages 290-297, the contents of which are incorporated herein by reference. This type of dry stretching is distinct from wet and particle stretching. In general, in the wet process, also known as phase inversion, extraction, or TIPS, the polymeric raw material is mixed with a processing oil (sometimes called a plasticizer), the mixture is extruded, and the processing oil is then removed to form pores (stretching of the film can be done before or after the oil is removed). See, for example, Kesting, Ibid. pages 237-286, the contents of which are incorporated herein by reference. Films formed by wet processes can also be stretched.

[0004] One problem that is seen to varying degrees with microporous membranes in certain dry processes (including the CELGARD and particle stretch processes and dry BOPP) is the problem of cracking, e.g., splitting along the MD, e.g., tearing or splitting (or MD splittiness). This is less of an issue in BNBOPP products, but longitudinal splitting is still an issue with BNBOPP. The problem of MD splittiness is exacerbated in thin walled microporous membranes because there is no "extra meat" to make up for the MD splittiness that may be present in thicker membranes.

[0005] The microporous membrane produced by the dry process is used as a thin-walled battery separator or as a thin-walled battery shut-down It is particularly important to solve the MD cracking problem when the separator is used as a separator for a microporous membrane battery. In addition to minimizing the space occupied by the battery, the separator for the microporous membrane battery may be thin-walled to reduce the conduction resistance. In addition to being thin-walled, the microporous membrane separator should also have sufficient strength to resist rupture (e.g., improve puncture strength and / or reduce MD cracking). If MD cracking or tearing occurs, the separator becomes difficult to handle, especially in the battery manufacturing process. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, microporous membranes with improved performance, such as reduced MD cracking, and methods for making the same are desirable. [Means for solving the problem]

[0007] Disclosed herein are new or improved substrate films, membranes, layers, or separators for impregnation, impregnated substrate films, membranes, layers, or separators, products incorporating the impregnated substrate films, membranes, layers, or separators, and / or related methods. The impregnated substrate films, membranes, layers, micro-layers, or separators can be one or more layers or micro-layers of a multi-layer or composite structure. For example, the impregnated substrate films, membranes, layers, micro-layers, or separators can be laminated to one or more other impregnated or non-impregnated substrate films, membranes, layers, micro-layers, and / or separators, and / or to other substrates, materials, layers, and / or the like. Also, the impregnated substrate film, membrane, layer, microlayer, or separator may be fully impregnated, partially impregnated, impregnated on a first side with a first material and a second side with a second material, impregnated with a first material and over-impregnated with a second material, and / or the like. The impregnation depth can be controlled by, for example, but not limited to, the selection of the substrate film, the selection of the impregnating material, or both. For example, the substrate film may have a large pore surface or layer or a smaller pore surface or layer. As another example, the impregnating material can be selected, made, or mixed to have high viscosity, low viscosity, high wetting, low wetting, good permeability, low permeability, and / or the like. In accordance with at least certain embodiments, the present application or invention relates to or provides improved polymer impregnated substrate films for making improved impregnated membranes for use in battery separators, such as secondary lithium ion batteries, and for other applications such as textiles, filtration, humidity control, and the like, and related methods of making and using the substrate films, impregnated substrate films, battery separators, and / or the like.In accordance with at least selected embodiments, the present application or invention relates to new and / or improved microporous polyolefin membranes that can be used as or in separators for batteries, lithium batteries, lead acid batteries, capacitors, fuel cells, lithium ion batteries, polymer batteries, CE, EDV, ESS, UPS, and / or ISS batteries, and new and / or improved methods that can be used to form the membranes and / or separators. According to at least certain embodiments, the present application or invention relates to microporous membranes that exhibit unique pore structures, impregnation structures, reduced cracking, e.g., machine direction (MD) cracking, improved pin puncture strength, improved elongation at break, improved hole shape (round, not split) in TMA or compression TMA testing, improved nail penetration test results (NPT pass), improved transverse direction (TD) tensile strength, improved balance of MD and TD strength properties, improved functionalization, improved ionic conductivity, can shut down, can have tackiness (adhesive surface), can be ceramic coated, can be IR detectable, can be SEM detectable, can be catalytic, can be crosslinked, and / or can provide other improved performance, functionality, and / or characteristics. Also disclosed herein are methods of making and / or using the same.

[0008] In one aspect, a method for forming a microporous polymeric membrane is disclosed herein. The method, in some embodiments, includes the steps of: (1) extruding a polymer to form a nonporous precursor film oriented in the machine direction; (2) stretching the machine-oriented nonporous precursor film in a low temperature environment having a temperature between 5 and 55 degrees Celsius to form a nanoporous precursor film; (3) stretching the nanoporous precursor film in a high temperature environment having a temperature between 80 and 200 degrees Celsius to form a microporous precursor film; and (4) optionally subjecting the microporous precursor film to one or more additional steps. In some embodiments, the stretching in the high temperature environment includes, consists of, or consists essentially of stretching the oriented precursor film along at least two of the following directions: machine direction, transverse direction perpendicular to the machine direction, or oblique direction at an angle other than 90 degrees to the machine direction. This type of stretching combination is for obtaining larger pores, such as pores with diameters greater than 0.50 um.

[0009] In some embodiments, the extrusion step can be part of a cast film extrusion process, a blown film extrusion process, or a coextrusion process.

[0010] In embodiments where the extrusion step is part of a cast film extrusion process, the extruded polymer can comprise, consist of, or consist essentially of a polyolefin polymer, such as polypropylene, polyethylene, or mixtures thereof, and the polyolefin polymer can be extruded without the use of plasticizers, solvents, or oils.

[0011] In embodiments where the extrusion step is part of a blown film extrusion process, the extruded polymer can comprise, consist of, or consist essentially of a polyolefin, such as polypropylene, polyethylene, or mixtures thereof. In some embodiments, the extruded polymer comprises, consists of, or consists essentially of a polymer having at least one of a melt index between 0.2 and 0.5 and / or a weight average molecular weight of 450,000 or less. In some embodiments, the extruded polymer comprises, consists of, or consists essentially of a polymer having at least one of a melt index between 0.3 and 0.5 and / or a weight average molecular weight of 400,000 or less. In some embodiments, the extruded polymer comprises, consists of, or consists essentially of a polymer having a weight average molecular weight of 1 million or less or a melt index between 0.02 and 0.15. The polymer can be extruded with at least one other ingredient, such as a processing oil and / or an organic or inorganic filler. In some embodiments, the extrusion of the polymer is performed without any other ingredients. For example, the extrusion is carried out without the use of processing oils or solvents.

[0012] In some embodiments of the blown film extrusion process, at least one or at least two air rings may be utilized. In embodiments where at least two air rings are used, the at least two air rings are positioned along a common axis. In some embodiments of the blown film extrusion process, a blow ratio (BUR) of about 0.5 to 7, more preferably 0.8 to 1.5, is utilized.

[0013] In some embodiments, the non-porous precursor film formed by extrusion is annealed prior to stretching in a low or high temperature environment, while in some other embodiments, the non-porous precursor film is not subjected to an annealing treatment.

[0014] The stretching in the high temperature environment after stretching in the low temperature environment can include, consist of, or consist essentially of stretching the nanoporous precursor film 50% to 500% (0.5x to 5x) in the machine direction (MD) with or without change in the transverse direction (TD). The stretching in the high temperature environment can include, consist of, or consist essentially of stretching the nanoporous precursor film 100% to 1000% (1x to 10x) in the transverse direction (TD) with or without change in the machine direction (MD). In other embodiments, the stretching in the high temperature environment can include, consist of, or consist essentially of stretching the nanoporous precursor film simultaneously or sequentially in any order in the machine direction and in the transverse direction with controlled machine direction relaxation.

[0015] In some embodiments, after stretching in a high temperature environment, the stretched porous membrane is calendered to form a calendered microporous polymeric membrane. The pores of the microporous polymeric membrane can then be filled with a pore-filling composition comprising a polymer, optionally in an amount of 1-20% by weight, and a solvent. In some embodiments, the walls of the pores are coated with the pore-filling composition.

[0016] In another aspect, a microporous polymeric membrane made according to the methods described herein is disclosed. In some embodiments, the microporous polymeric membrane has a composite splittiness index (CSI, as defined in Equation 2 below) of greater than 140, greater than 150, greater than 160, greater than 170, greater than 180, greater than 190, or greater than 200. The microporous membrane can have circular or irregular shaped pores. The pores can be relatively uniform throughout the membrane or asymmetric with respect to the Z direction and can be circular, oval, trapezoidal, spherical, or slit-like, or combinations thereof. In some preferred embodiments, the microporous membrane can be a monolayer, bilayer, trilayer, or multilayer membrane. The thickness of the microporous membrane can be between 4 and 40 microns. The TD tensile strength of the microporous membrane is improved by adding TD stretching (with or without MD relaxation) and / or by impregnating or coating the membrane with one or more polymer-based impregnation materials. In some embodiments, the membrane has a better balance of MD and TD tensile strength values, e.g., the ratio of MD tensile strength value to TD tensile strength value is preferably as close to 1:1 as possible. For example, this can be between 0.98:1 and 1.7:1.

[0017] In another aspect, a battery separator is disclosed that comprises, consists of, or consists essentially of the microporous membrane described herein. In a particularly preferred embodiment, the battery separator has a coating on at least one surface thereof. The coating preferably comprises, consists of, or consists essentially of a polymer and organic particles, inorganic particles, or a mixture of organic and inorganic particles.

[0018] In another aspect, a secondary lithium ion battery comprising any one of the separators described herein is disclosed.

[0019] In a further aspect, there is described a composite comprising any of the battery separators described herein in direct contact with a secondary lithium ion battery electrode.

[0020] In yet another aspect, a vehicle or device is described that includes any of the battery separators described herein. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 illustrates an exemplary cast film extrusion process. [Diagram 2] An example of a blown film extrusion process is shown in FIG. [Diagram 3] FIG. 3 shows an example of a coextrusion process. [Figure 4] FIG. 4 shows an example of a coextrusion process. [Diagram 5] FIG. 5 shows an SEM of an exemplary longitudinally oriented non-porous precursor. [Figure 6] FIG. 6 shows an SEM of an exemplary extruded and annealed longitudinally oriented non-porous precursor film. [Figure 7] FIG. 7 shows the longitudinally oriented non-porous precursor stretched in the longitudinal direction (A) and in the transverse direction (B) perpendicular to the longitudinal direction. [Figure 8] FIG. 8 shows the direction of the rollers as indicated by the double arrow. [Figure 9] FIG. 9 shows an SEM of the surface of a non-porous precursor film that was stretched in the machine direction only. [Figure 10] FIG. 10 shows an SEM of the surface of a non-porous precursor film that was stretched in the machine direction only. [Figure 11] FIG. 11 shows a microporous precursor film obtained by only MD hot stretching (left) and a microporous precursor obtained by both MD and TD hot stretching (right). [Figure 12A] FIG. 12A shows a separator, substrate film, or membrane that is coated on one side. [Figure 12B]FIG. 12B shows a battery separator, substrate film, or membrane that is coated on both sides. [Figure 13] FIG. 13 illustrates an embodiment of a lithium ion battery. [Figure 14] FIG. 14 shows a scanning electron microscope photograph of the surface of an example of an MD-stretched dry-process membrane. [Figure 15] FIG. 15 shows a scanning electron microscope photograph of the surface of an example of an MD-stretched dry-process membrane. [Figure 16] FIG. 16 shows the orientation of the lamellae, the orientation of the fibrils or bridge structures between adjacent lamellae, etc. [Figure 17] FIG. 17 shows the orientation of the lamellae, the orientation of the fibrils or bridge structures between adjacent lamellae, etc. [Figure 18] FIG. 18 is a schematic representation of a PO-based film membrane (left) and a treated, pore-filled, or polymer-impregnated PO membrane (right). [Figure 19] FIG. 19 shows surface and cross-sectional SEM images of pore-filled or polymer-impregnated PO membranes. [Figure 20] FIG. 20 is a surface SEM image of a TDC PP membrane configured for pore filling or polymer impregnation. [Figure 21] FIG. 21 is a surface SEM image of a TDO trilayer membrane (PP / PE / PP) configured for pore filling or polymer impregnation. [Figure 22] FIG. 22 is a surface SEM image of a TDC tri-layer membrane (PP / PE / PP) configured for pore filling or polymer impregnation. [Diagram 23] FIG. 23 is a surface SEM image of a trilayer membrane (PP / PP / PP / PE / PE / PE / PP / PP / PP) having nine microlayers configured for pore filling or polymer impregnation. [Figure 24] FIG. 24 is an image of an exemplary circular hole geometry of a pore-filled or polymer-impregnated TDO membrane. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (1) an extrusion step to form a non-porous precursor film The extrusion step can be part of a cast film extrusion process, a blown film extrusion process, or a coextrusion process. An exemplary cast film extrusion process is shown in FIG.

[0023] An example of a blown film extrusion process is shown in Figure 2. An example of a coextrusion process is shown in Figure 3.

[0024] Another example of a coextrusion process is shown in FIG.

[0025] The extruded polymer can comprise, consist of, or consist essentially of at least one polymer. In a preferred embodiment, the polymer is one or more polyolefins, such as polypropylene or polyethylene, copolymers, block copolymers, blends, polyolefin blends, blends with other polymers, materials, or additives, or combinations thereof. Each layer or microlayer can be the same polymer or a copolymer, block copolymer, blend, polyolefin blend, blend with other polymers, materials, or additives, or combinations thereof. In another potentially preferred embodiment, the polyolefin (PO) is a high or ultra-high molecular weight polyolefin alone or in combination with a lower molecular weight polyolefin (which may also include other additives, agents, or fillers, one of which is an elastomer, another is a stearate, another is a crosslinker, another is a polymer or copolymer, and / or the like). In certain potentially preferred embodiments, the outer material, surface, layer, or layers comprises a polypropylene (PP) layer, and optionally one or more inner material, layer, or layers comprises polyethylene (PE).

[0026] In some embodiments, the polyolefins described herein can be ultra-low molecular weight, low molecular weight, medium molecular weight, high molecular weight, or ultra-high molecular weight polyolefins, such as medium or high molecular weight polyethylene (PE) or polypropylene (PP). For example, the molecular weight of the ultra-high molecular weight polyolefin can be 450,000 (450k) or more, such as 500k or more, 650k or more, 700k or more, 800k or more, etc. The molecular weight of the high molecular weight polyolefin can be in the range of 250k to 450k, such as 250k to 400k, 250k to 350k, or 250k to 300k. The molecular weight of the medium molecular weight polyolefin can be 150 to 250k, such as 150k to 225k, 150k to 200k, 150k to 200k, etc. The molecular weight of the low molecular weight polyolefin can be in the range of 100k to 150k, for example, in the range of 100k to 125k. The molecular weight of the ultra-low molecular weight polyolefin can be less than 100k. The above values ​​are weight average molecular weights. In some embodiments, higher molecular weight polyolefins can be used to improve the strength or other properties of the microporous membranes described herein or batteries comprising the same. In modified dry processes, small amounts of solvents or oils can be used, and polymers with molecular weights of about 600k or more can be used. In some embodiments, lower molecular weight polymers, such as medium, low, or ultra-low molecular weight polymers, can be advantageous.

[0027] In a preferred embodiment of the dry process (or dry stretch), no solvent or oil is used to extrude the polymer. In other embodiments, the polymer can be extruded with one or more additional components, including organic or inorganic fillers. In a preferred embodiment, the extrusion step can be part of a dry process such as the CELGARD® process, the TD or TDO dry process, the TDC dry process, the BOPP dry process, the biaxially stretched dry process, a wet or dry process to produce a very thin polyolefin membrane film or product, or a BNBOPP process in which the polymer is extruded with a β-nucleating agent.

[0028] If the extrusion step is part of a coextrusion process, such as that shown in Figures 3 and 4 above, the coextruded polymers may be the same or different, respectively. Each of the polymers dispensed can be as described herein above.

[0029] If the extrusion step is part of a blown film extrusion process, such as that shown above in Figures 2 and 4, the process can utilize at least one air ring or at least two air rings. In some embodiments, it is preferred to use at least two air rings.

[0030] In other preferred embodiments where the extrusion step is part of a blown film extrusion process, the blow ratio can be between 0.5 and 7, and in preferred embodiments, between 0.8 and 1.5. Different blow ratios can be achieved by varying the die aperture or the fold diameter of the cylindrical film. The blow ratio is calculated according to the following formula (1): BUR = (0.637 × folding diameter) / die diameter (1)

[0031] The longitudinally oriented non-porous precursor film formed by the extrusion step is not so limited. The film can comprise, consist of, or essentially consist of one layer, one ply, a single layer, two or more layers, two or more plies, multiple layers, one or more fine layers, three or more fine layers, one or more extruded or co-extruded films, and / or can be a composite structure comprising, consisting of, or essentially consist of two or more (possibly, preferably three or more) extruded or co-extruded films laminated together, each film having one or more layers, plies, fine layers, or the like. A longitudinally oriented non-porous precursor film does not have micropores. It is a film that has not yet been stretched to form pores, e.g., has not yet been stretched in the machine direction (MD) or transverse direction (TD). An SEM of an exemplary longitudinally oriented non-porous precursor is shown in FIG. 5.

[0032] In some embodiments, the longitudinally oriented non-porous precursor film can be annealed prior to cold or hot stretching. Without wishing to be bound by theory, it is believed that the annealing step can complete the aligned row lamellar structure. For example, an SEM of an exemplary extruded and annealed longitudinally oriented non-porous precursor film is shown in FIG. 6.

[0033] (2) a hot stretching step to form a microporous membrane or film; The stretching step is not so limited and can include, consist of, or consist essentially of stretching the longitudinally oriented non-porous precursor along at least two of the following directions: the longitudinal direction (A in FIG. 7), a transverse direction perpendicular to the longitudinal direction (B in FIG. 7), or a diagonal direction intersecting the longitudinal direction and forming an angle other than 90 degrees (all other lines in FIG. 7).

[0034] With respect to FIG. 7, the lines indicating the diagonal directions are not limiting. Forming an angle other than 90 degrees with the machine direction means only that the diagonal direction is not along (i.e., is not the same as) the transverse direction perpendicular to (i.e., forms 90 degrees with) the machine direction. The stretching can be performed simultaneously or sequentially in any order. In a preferred embodiment, the machine-oriented nonporous precursor film is cold stretched and then hot stretched simultaneously or sequentially in any order along the machine direction and along the transverse direction and at least one of the diagonal directions intersecting the machine direction at any angle other than 90 degrees. In some embodiments, the hot stretching can be performed as follows: simultaneously along the machine direction and along the transverse direction; simultaneously along the machine direction and along the diagonal direction; sequentially along the machine direction and the transverse direction in any order; sequentially along the machine direction and along the diagonal direction in any order; sequentially along the machine direction and along two or more different diagonal directions in any order; sequentially along the machine direction, along the transverse direction, and along at least one diagonal direction. Next, in any order. Without wishing to be bound by theory, it is believed that hot stretching in the machine direction and at least one of the transverse or oblique directions with controlled relaxation in the machine direction results in a microporous membrane with improved properties including reduced machine cracking, improved TD strength, and / or the like. It is believed that such a hot stretching step can improve orientation in the transverse and / or oblique directions and contribute to reduced cracking, such as machine direction (MD) cracking.

[0035] Stretching can be accomplished by any means consistent with the goals set forth herein. In some embodiments, stretching is accomplished using sequential speed rollers and / or tenter frame stretching equipment. Stretching along a diagonal direction can be accomplished using rollers that are oriented at an angle to the machine direction of the film as the film enters the rollers. For example, the rollers can be oriented in the direction shown by the double-headed arrow in FIG. 8.

[0036] SEMs of the surface of a non-porous precursor film stretched only in the machine direction are shown in Figures 9-10.

[0037] (3) Annealing, stretching, and then heat setting The heat setting to form the final mesoporous or microporous film after stretching is not so limited. In some embodiments, the heat setting step can form a final microporous membrane that can be used, for example, as a battery separator or as a substrate film to be coated or impregnated. In other embodiments, the microporous membrane or film is subjected to further processing steps, such as calendaring and pore filling, to form a final microporous or nanoporous membrane that can be used as a battery separator.

[0038] The hot stretching can be carried out at a temperature of 80-200 degrees Celsius, 90-150 degrees Celsius, 100-140 degrees Celsius, 105-135 degrees Celsius, 110-130 degrees Celsius, or 120-125 degrees Celsius. For example, the hot stretching can be carried out in an oven at any temperature within these ranges.

[0039] The machine direction (MD) stretching, especially the first or initial MD hot stretching, can form pores in the non-porous membrane precursor. The machine direction (MD) hot stretching can be performed as a single step or multiple steps. In one embodiment, the total machine direction stretching ratio can be in the range of 50-500% (i.e., 0.5-5x), and in another embodiment, it can be in the range of 100-300% (i.e., 1-3x). This means that the width (in the MD direction) of the membrane precursor increases by 50-500% or 100-300% during the MD hot stretching compared to the initial width, i.e., before any stretching. In some preferred embodiments, the membrane precursor is stretched in the range of 180-250% (i.e., 1.8-2.5x). During the machine direction stretching, the precursor can shrink in the transverse direction. In some preferred embodiments, TD relaxation of 10-90%, 20-80%, 30-70%, 40-60%, at least 20%, 50%, etc. is performed during or after MD stretching, preferably after, or during or after at least one step of MD stretching, preferably after. Without wishing to be bound by a particular theory, it is believed that by performing MD high-temperature stretching while performing TD relaxation, the pores formed by MD stretching are maintained small. In other preferred embodiments, TD relaxation is not performed.

[0040] The MD tensile strength of the membrane precursor that has been subjected to only MD hot stretching (not TD hot stretching) is high, e.g., 150 kg / cm 2 or more than 200kg / cm 2 However, the TD tensile strength and pin puncture strength of such a membrane precursor that has been subjected to only MD hot stretching may not be ideal. The pin puncture strength may be, for example, less than 300 gf. The TD tensile strength is, for example, 200 kg / cm 2 Less than or 150kg / cm 2 It may be less than.

[0041] Thus, particularly preferred embodiments are those in which hot stretching is carried out in both the machine and transverse directions.

[0042] The transverse direction (TD) hot stretching of the precursor is not particularly limited and can be carried out in any manner consistent with the objectives set forth herein. The transverse direction stretching can be carried out in a single step or multiple steps. In one embodiment, the total transverse hot stretching ratio can be in the range of 100-1200%, in the range of 200-900%, in the range of 450-600%, in the range of 400-600%, in the range of 400-500%, etc. In one embodiment, the controlled longitudinal relaxation can be in the range of 5-80%, and in another embodiment, in the range of 15-65%. In one embodiment, the TD hot stretching can be carried out in multiple steps. The precursor may or may not be allowed to shrink in the longitudinal direction during the transverse hot stretching. In one embodiment where the transverse hot stretching is performed in multiple steps, a first transverse hot stretching step may include a transverse hot stretching with a controlled longitudinal relaxation, followed by simultaneous transverse and longitudinal stretching, followed by a transverse relaxation without longitudinal stretching or longitudinal relaxation. For example, the TD hot stretching may be performed with or without a longitudinal (MD) relaxation. In some preferred embodiments, this involves a MD relaxation of 10-90%, 20-80%, 30-70%, 40-60%, at least 20%, 50%, etc.

[0043] The transverse (TD) hot stretching can improve the tensile strength in the transverse direction and reduce the cracking of the microporous membrane, for example, compared to a microporous membrane that has not been subjected to TD hot stretching during production and has only been subjected to longitudinal hot stretching. It is also possible to reduce the thickness, which is desirable. However, TD stretching can also reduce the JIS Gurley, for example, to less than 100 or less than 50, and the porosity of the MD and TD hot stretched membrane can also increase compared to a precursor that has only been subjected to MD hot stretching. At least part of the reason for this may be the larger micropore size, as shown in Figure 11. Figure 11 shows a microporous precursor film (left) obtained by only MD hot stretching and a microporous precursor (right) obtained by MD and TD hot stretching. The double-headed arrow indicates the MD direction.

[0044] The microporous precursor of Figure 11 will have a different pore structure than that shown in Figure 11 if diagonal stretching was part of the manufacturing process. For example, the pores may have a more irregular shape rather than being slit-shaped (left side of Figure 11) or circular (right side of Figure 11).

[0045] (4) Optional Additional Steps In some embodiments, the microporous precursor film is the final microporous membrane product, but in some embodiments, the microporous precursor film can be subjected to one or more additional steps to obtain a microporous membrane. The methods described herein can further include, for example, subjecting the microporous precursor film to at least one of the following additional steps: (a) a calendering step, (b) an additional high-temperature or low-temperature stretching step as described herein above, (c) an additional high-temperature TD stretching step (with or without MD relaxation) as described herein above, and (d) a pore-filling or impregnation step. In some embodiments, at least two, at least three, or all four of steps (a)-(d) can be performed.

[0046] The calendering step is not so limited and may be any step not inconsistent with the goals set forth herein. The calendering process can be carried out in a method. For example, in some embodiments, the calendering step can be carried out as a means to reduce the thickness of the microporous precursor film, to controllably reduce the porosity of the microporous precursor film, and / or to further improve the transverse direction (TD) tensile strength or pin puncture strength of the microporous precursor film. Calendering can also improve the strength, wettability, and / or uniformity, and can also reduce surface layer defects introduced during the manufacturing process, for example, during the MD and TD stretching processes. The calendered microporous precursor film can have improved coatability. The use of textured calendering rolls can help improve the adhesion of the coating to the substrate film.

[0047] Calendering can be performed at low (below room temperature), ambient (room temperature), or high (e.g., 90° C.) temperatures and can include the application of pressure or heat and pressure to controllably reduce the thickness of the membrane or film. In addition, the calendering process can use at least one of heat, pressure, and speed to densify the heat-sensitive material. Furthermore, the calendering process can use uniform or non-uniform heat, pressure, and / or speed to selectively densify the heat-sensitive material, obtain uniform or non-uniform calendering conditions (e.g., by using smooth rolls, textured rolls, patterned rolls, micropatterned rolls, nanopatterned rolls, speed changes, temperature changes, pressure changes, humidity changes, double roll steps, multi-roll steps, or combinations thereof), produce improved, desired, or unique structures, characteristics, and / or performance, produce or control the resulting structures, characteristics, and / or performance, and / or the like.

[0048] In preferred embodiments, calendering the microporous precursor film reduces the thickness of the microporous precursor film. In some embodiments, the thickness is reduced by 30% or more, 40% or more, 50% or more, or 60% or more. In some preferred embodiments, the thickness is reduced to 10 microns or less, and in some cases to 9, or 8, or 7, or 6, or 5, or 4 microns or less.

[0049] The pore filling, pore coating or impregnation step may include applying a pore filling composition to the macroporous, mesoporous or microporous precursor film, the pore filling composition may include a solvent and a polymer in an amount of 1-20% by weight of the total pore filling or coating composition. The pore filling composition may be applied by immersion coating. The coating may be applied by any coating method including roll coating, roll coating, dip coating, and the like.

[0050] Microporous membrane In another aspect, the microporous membranes described herein have improved cracking as measured by a test known as the Composite Cracking Index (CSI), which was developed to define the CSI value as Equation 2 (described below), where CSI is a function of the first peak load, second peak load, TD tensile strength, MD tensile strength, and TD elongation measured during a pin puncture test.

[0051] CSI=(A-|BA| 1.8 )×C×(D×E) / 10 6 (2) During the ceremony: A = first peak load / (thickness × (1-porosity (%))); B = second peak load / thickness; C=TD elongation; D=MD tensile strength; E = TD tensile strength; where the first and second peak loads are in gram force, the thickness values ​​are in microns, the MD and TD tensile strengths are in gram force, and the TD elongation is expressed as a percentage. High CSI values ​​predict that the microporous membranes will exhibit superior strength performance in lithium-ion batteries, both during the battery cell winding step in the manufacturing process and during the expansion and contraction of the membrane that may occur during repeated charge-discharge cycles throughout the life of the battery.

[0052] The microporous membranes described herein have a CSI value of greater than 140, greater than 150, greater than 160, greater than 170, greater than 180, greater than 190, greater than 200, or greater than 250.

[0053] The microporous membrane can be made according to any one of the methods disclosed herein. In some preferred embodiments, the microporous membrane has excellent properties even without the addition of a surface coating, such as a ceramic coating, which can enhance its properties.

[0054] In some preferred embodiments, for example, the thickness of the microporous membrane without additional surface coating thereon or the pore-coated membrane itself is in the range of 2-50 microns, 4-40 microns, 4-30 microns, 4-20 microns, 4-10 microns, or less than 10 microns. Thicknesses, for example, 10 microns or less, can be achieved with or without a calendering step. Thickness can be measured in micrometers, μm, microns, or um using an Emveco Microgage 210-A micrometer thickness tester and the test procedure of ASTM D374. Thinner microporous membranes are preferred for some applications. For example, when used as a battery separator, using thinner separator membranes allows more anodes and cathodes to be used in the battery, resulting in a battery with higher energy density and higher power density.

[0055] In some preferred embodiments, the JIS Gurley of the microporous membrane can range from 50 to 300, 75 to 300, and / or 100 to 300. However, the JIS Gurley value is not so limited and can be higher, e.g., greater than 300, or lower, e.g., less than 50, as desired for various purposes. Gurley herein is defined as the Japanese Industrial Standard (JIS Gurley) and is measured herein using an Oken air permeability tester. JIS Gurley is the air permeability of water per square inch (6.5 cm) when a constant pressure of 4.9 inches (12.5 cm) is applied to the water. 2 The time required to pass 100cc of air through the film is The JIS Gurley can be measured for the entire microporous membrane or for individual layers of the microporous membrane, e.g., for individual layers of a three-layer membrane. Unless otherwise specified herein, the JIS Gurley values ​​reported are for the microporous membrane. In at least one embodiment, low Gurley membranes are provided that have desired strength and / or other performance. In at least another embodiment, thin-walled, low Gurley membranes are provided that have desired strength and / or other performance (e.g., desired breaking elongation, pin puncture strength, shrinkage, reduced cracking, drop test pass performance, nail penetration test pass performance, and / or the like).

[0056] In some preferred embodiments, the pin puncture strength of the microporous membrane is greater than 250 (gf) when unnormalized, or greater than 300, greater than 350, or greater than 400 (gf) when normalized for thickness / porosity, e.g., normalized to a thickness of 14 microns and porosity of 50%. In some cases, the pin puncture strength is between 300-700 (gf), between 300-600 (gf), between 300-500 (gf), between 300-400 (gf), etc. In some embodiments, the pin puncture strength can be less than 300 gf or greater than 600 gf, as desired for a particular application, although one manner in which the disclosed microporous membranes can be used is described. A range that works well for battery separators is 300 (gf) to 700 (gf). Pin puncture strength is measured using an Instron Model 4442 in accordance with ASTM D3763. Measurements are taken across the width of the microporous membrane. Pin puncture strength is defined as the force required to pierce a test specimen.

[0057] The pin puncture strength and thickness measurements for any microporous membrane (e.g., having any porosity or thickness) can be normalized to a thickness of 14 microns and a porosity of 50% using the following formula (3): [Measured puncture strength (gf) 14 microns] / [Measured thickness (microns) porosity 50%] (3)

[0058] Normalizing the measured pin puncture strength values ​​allows thicker or thinner microporous membranes to be compared together: a thicker microporous membrane made in the same manner as its thinner counterpart will often have a pin puncture strength due to its greater thickness.

[0059] In some preferred embodiments, the porosity of the microporous membrane, e.g., surface porosity, is about 20 to about 90%, optionally about 30 to about 80%, optionally about 40 to about 70%, optionally about 45 to about 65%, etc. In some embodiments, the porosity can be greater than 70% or less than 40% if desired for a particular application, but a range that works for battery separators, one mode in which the disclosed microporous membranes can be used, is 40 to 70%. Porosity is measured using ASTM D-2873 and is defined as the percentage of voids, e.g., pores, within the microporous membrane area as measured in the machine direction (MD) and transverse direction (TD) of the substrate. The porosity can be measured for the entire microporous membrane or for individual layers of the microporous membrane, e.g., individual layers of a three-layer membrane. Unless otherwise specified herein, the porosity values ​​reported are for the microporous membrane.

[0060] In some preferred embodiments, the microporous membrane has high machine direction (MD) and transverse direction (TD) tensile strength. Machine direction (MD) and transverse direction (TD) tensile strength are measured according to the procedure of ASTM-882 using an Instron model 4201. In some embodiments, the TD tensile strength is 250 kg / cm 2 More than 300kg in some cases / cm 2 or more, and in some cases 400kg / cm 2 or more, and in some cases 500kg / cm 2 That's all. Regarding MD tensile strength, the MD tensile strength is sometimes 500kg / cm 2 More than 600kg / cm 2 More than 700kg / cm 2 More than 800kg / cm 2 More than 900kg / cm 2 or more than 1000kg / cm 2 That's all. MD tensile strength is 2000kg / cm 2 It can also be made higher.

[0061] In some preferred embodiments, the shrinkage in machine direction (MD) and transverse direction (TD) of the microporous membrane can be reduced even without applying a coating, such as a ceramic coating. For example, the MD shrinkage at 105°C can be 20% or less or 15% or less. The MD shrinkage at 120°C can be 35% or less, 29% or less, 25% or less, etc. The TD shrinkage at 105°C can be 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, or 4% or less. The TD shrinkage at 120°C can be 12% or less, 11% or less, 10% or less, 9% or less, or 8% or less. The shrinkage is measured by placing a test specimen, such as a microporous membrane without a coating thereon, between two sheets of paper, which are then sandwiched together to hold the test specimen between the papers, and hanging in an oven. For testing at 105°C, the specimens are placed in a 105°C oven for a specified time, e.g., 10 minutes, 20 minutes, or 1 hour. After the specified time in the oven, each specimen is removed and placed on a flat table, smoothed flat to accurately measure the length and width of the specimen, and attached using double-sided adhesive tape. Shrinkage is measured in the MD, i.e., to measure MD shrinkage, and in the TD, i.e., to measure MD shrinkage, the specimens are placed flat on a flat table, smoothed flat to accurately measure the length and width of the specimen. To measure shrinkage (perpendicular to the MD direction), ie, TD shrinkage, measurements were taken in both directions and expressed as MD shrinkage (%) and TD shrinkage (%).

[0062] In some preferred embodiments, the average dielectric breakdown of the microporous membrane is between 900 and 2000 volts. Dielectric breakdown voltage measurements were performed by placing a specimen of the microporous membrane between two stainless steel pins, each with a circular flat tip of 2 cm in diameter, applying increasing voltage between the pins using a Quadtech Model Sentry 20 Hi-Pot Tester, and recording the displayed voltage (the voltage at which current was discharged through the specimen).

[0063] In some preferred embodiments, the uncoated microporous membrane or the microporous membrane prior to application of any coating, e.g., a ceramic coating, has the following properties: TD tensile strength of 250 kg / cm 2 Ultra; normalized or pre-normalized puncture Tensile strength greater than 300 gf; and JIS Gurley greater than 50. In some embodiments, the JIS Gurley is between 50 and 300, or between 100 and 300, and the TD tensile strength is 250 kg / cm 2 In some embodiments, the puncture strength is greater than 300 gf. The pin puncture strength before normalization or after normalization to thickness and porosity, e.g., 14 microns thick and 50% porosity, is between 300 and 600 (gf), and in some cases, the pin puncture strength before normalization or after normalization to thickness and porosity, e.g., 14 microns thick and 50% porosity, is between 400 and 600 (gf), and the TD tensile strength is 250 kg / cm 2 and the JIS Gurley is greater than 50. The degree is 250kg / cm 2 ~600kg / cm 2 Between 250 and 590 kg / cm 2 During and 250~500kg / cm 2 Between these, the JIS Gurley is over 50, and the puncture strength is Over 300 (gf).

[0064] In some preferred embodiments, the MD / TD tensile strength ratio can be 1-5, 1.45-2.2, 1.5-5, 2-5, and the like.

[0065] The microporous membranes and separators disclosed herein can have improved heat resistance, for example, exhibiting desirable behavior in a hot tip hole propagation study. The hot tip study measures the dimensional stability of the microporous membrane under point heating conditions. The test involves contacting the separator with a hot soldering iron tip and measuring the resulting hole. Smaller holes are generally more desirable. In some embodiments, the hot tip propagation can be 2-5 mm, 2-4 mm, 2-3 mm, or less than these values.

[0066] In some embodiments, the tortuosity can be greater than 1, greater than 1.5, or greater than 2 or more, but is preferably between 1 and 2.5. It has been found that having a microporous separator membrane with a high tortuosity between the electrodes of a battery is advantageous to avoid battery failure. A membrane with straight through holes is defined as having a tortuosity of unity. For at least certain preferred battery separator membranes in which dendrite growth is inhibited, a tortuosity value greater than 1 is preferred. More preferably, the tortuosity value is greater than 1.5. Even more preferably, the separator has a tortuosity value greater than 2. Without wishing to be bound by any particular theory, the tortuosity of the microporous structure of at least certain preferred dry and / or wet process separators (e.g., Celgard® battery separators) can play an important role in controlling and inhibiting dendrite growth. The pores of at least certain Celgard® microporous separator membranes provide a phase barrier that limits the growth of dendrites from the anode through the separator to the cathode. A network of interconnected twisted pathways can be created. The more tortuous the pore network, the higher the tortuosity of the separator membrane. Potentially preferred Celgard® membranes can be Celgard® Z-series membranes, or other Celgard® membranes, or separators that have been stretched to some degree in the TD (with or without MD relaxation).

[0067] In some embodiments, the static coefficient of friction (COF) may be less than 1, less than 0.9, less than 0.8, less than 0.7, less than 0.6, less than 0.5, less than 0.4, less than 0.3, less than 0.2, etc. The static COF (coefficient of friction) is determined according to the method described in "Paper and Paperboard - Method for Determining Static and Kinetic Coefficients of Friction" (2003). The friction coefficient is measured in accordance with JIS P8147 entitled "Friction of Paper and Board."

[0068] The pin pull force may be less than 1000 grams force (gf), less than 900 gf, less than 800 gf, less than 700 gf, less than 600 gf, etc. The pin pull test is now described as follows: A battery winding machine was used to wind a separator (comprising, consisting of, or consisting essentially of a porous substrate with a coating layer applied to at least one surface thereof) around a pin (or core or mandrel). The pin is a cylindrical mandrel having a diameter of 0.16 inches (0.41 cm) and two halves with a smooth outer surface. Each of the halves has a semicircular cross section. A separator, discussed below, is wound onto the pin. An initial force (tangential) of 0.5 kgf is applied to the separator, after which the separator is wound at a speed of 10 inches (25.4 cm) in 24 seconds. During winding, the separator being wound onto the mandrel is engaged by a tension roller. The tension roller consists of a 5 / 8 inch (1.6 cm) diameter roller located opposite the separator supply side, a 3 / 4 inch (1.9 cm) air cylinder to which 1 bar of air pressure is applied (when engaged), and a 1 / 4 inch (0.64 cm) rod connecting the roller and cylinder together.

[0069] The separator consists of two 30 mm (width) by 10 inch (25.4 cm) membrane specimens. Five pairs of these separators are tested, the results averaged, and the average reported. Each specimen is spliced ​​with a 1 inch (2.5 cm) overlap on the separator supply roll of the winding machine. The free end of the separator is marked with ink 1 / 2 inch (1.3 cm) and 7 inches (17.8 cm) from the distal end of the spliced ​​end. The 1 / 2 inch (1.3 cm) mark is aligned with the far side of the pin (i.e., the side adjacent to the tension roller), the separator is gripped between the pin halves, the tension roller is engaged, and winding is initiated. When the 7 inch (17.8 cm) mark is approximately 1 / 2 inch (1.3 cm) from the jelly roll (separator wrapped around the pin), cut the separator at the mark and secure the free end of the separator to the jelly roll with a piece of adhesive tape (1 inch (2.5 cm) wide, 1 / 2 inch (1.3 cm) overlap). Remove the jelly roll (i.e., pin with separator wrapped around it) from the winding machine. An acceptable jelly roll is one that is not wrinkled and has no telescoping.

[0070] The jelly roll is mounted in a tensile strength tester (i.e., Chatillon Model TCD500-MS, Chatillon Inc., Greensboro, NC) equipped with a load cell (50 lbs x 0.02 lbs; Chatillon DFGS50). The strain rate is 2.5 in (6.4 cm) per minute, and data from the load cell is recorded at a rate of 100 points per second. The peak force is reported as the pin pull force.

[0071] Battery separator In another aspect, a battery separator is described that comprises, consists of, or consists essentially of at least one microporous membrane disclosed herein. In some embodiments, at least one microporous membrane can be coated on one or both sides to form a battery separator that is coated on one or both sides. The single-sided coated separator, substrate film, or membrane and the double-sided coated battery separator, substrate film, or membrane according to some embodiments herein are shown in FIG. 12.

[0072] The coating layer can comprise, consist of, consist essentially of, and / or be formed from any coating composition or deposit (e.g., organic, inorganic, polymeric, gel, ceramic, metallic, clay, filled, unfilled, adhesive, conductive, non-conductive, porous, non-porous, continuous, discontinuous, or combinations thereof). For example, any of the coating compositions described in U.S. Pat. No. 6,432,586 can be used. The coating layer can be wet, dry, crosslinked, uncrosslinked, etc.

[0073] In one aspect, the coating layer can be the outermost coating layer of the separator, e.g., it can have no other different layers formed thereon, or it can have at least one other different coating layer formed thereon. For example, in some embodiments, a different polymer coating layer can be coated on or on top of the coating layer formed on at least one surface of the porous substrate. In some embodiments, the different polymer coating layer can include, consist of, or consist essentially of at least one of polyvinylidene difluoride (PVdF) or polycarbonate (PC).

[0074] In some embodiments, the coating layer is applied on top of one or more other coating layers already applied to at least one side of the microporous membrane. For example, in some embodiments, these layers already applied to the microporous membrane are thin, very thin, or ultrathin layers of at least one of inorganic materials, organic materials, conductive materials, semiconductive materials, nonconductive materials, reactive materials, or mixtures thereof. In some embodiments, these layers are metal or metal oxide-containing layers. In some preferred embodiments, metal-containing layers and metal oxide-containing layers, such as metal oxides of the metals used in the metal-containing layers, are formed on the porous substrate prior to forming a coating layer comprising the coating composition described herein. In some cases, the total thickness of these already applied layers or layers is less than 5 microns, in some cases less than 4 microns, in some cases less than 3 microns, in some cases less than 2 microns, in some cases less than 1 micron, in some cases less than 0.5 microns, in some cases less than 0.1 microns, and in some cases less than 0.05 microns.

[0075] In some embodiments, the thickness of a coating layer formed from the coating compositions described herein above, such as those described in U.S. Patent No. 8,432,586, is less than about 12 μm, in some cases less than 10 μm, in some cases less than 9 μm, in some cases less than 8 μm, in some cases less than 7 μm, in some cases less than 5 μm. In at least certain selected embodiments, the coating layer is less than 4 μm, less than 2 μm, or less than 1 μm.

[0076] The coating method is not particularly limited, and the coating layer described herein can be coated, for example, on the porous substrate described herein by at least one of the following coating methods: extrusion coating, roll coating, gravure coating, printing, knife coating, air knife coating, spray coating, etc. The coating process can be carried out at room temperature or at elevated temperatures.

[0077] The coating layer can be either non-porous, nano-porous, micro-porous, meso-porous, or macro-porous. The JIS Gurley of the coating layer can be 700 or less, and in some cases 600 or less, 500 or less, 400 or less, 300 or less, 200 or less, or 100 or less. For non-porous coating layers, the JIS Gurley can be 800 or more, 1,000 or more, 5,000 or more, or 10,000 or more (i.e., "infinite Gurley"). For non-porous coating layers, the coating is non-porous when dry, but is a good ionic conductor, especially when wetted with an electrolyte.

[0078] Complex or device A composite or device comprising any of the battery separators described hereinabove and one or more electrodes, such as an anode, a cathode, or an anode and a cathode, disposed in direct contact therewith. The type of electrode is not particularly limited. For example, the electrode may be suitable for use in a lithium ion secondary battery.

[0079] A lithium ion battery according to some embodiments herein is shown in FIG.

[0080] While any cathode and anode are contemplated, potentially preferred anodes may have an energy capacity of 372 mAh / g or greater, preferably ≧700 mAh / g, and most preferably ≧1000 mAH / g. The anode may be comprised of a lithium metal foil or a lithium alloy foil (e.g., lithium aluminum alloy), or a mixture of metallic lithium and / or lithium alloys with materials such as carbon (e.g., coke, graphite), nickel, copper, and the like. The anode may or may not be made exclusively of lithium-containing intercalation compounds or lithium-containing insertion compounds.

[0081] A suitable cathode can be any cathode compatible with the anode and can include an intercalation compound, an insertion compound, or an electrochemically active polymer. Suitable intercalation compounds include, for example, MoS 2 , FeS 2 , MnO 2 , TiS 2 , NbSe 3 , LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , V 6 O 13 , V 2 O 5 , and CuCl 2 Suitable examples include: Polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiopene.

[0082] Any of the battery separators described herein above can be incorporated into any vehicle, such as an electric vehicle, or device, such as a cell phone or laptop computer, that is fully or partially battery powered.

[0083] SUMMARY OF THE DISCLOSURE New or improved impregnation substrate films, impregnated substrate films, products incorporating impregnated substrate films, and / or related methods are shown, claimed or described herein.

[0084] Several different types of dry-stretched microporous membranes are described and illustrated below: MD stretching only; MD+TD stretching (TD) (or TDO) (MD relaxation may be preferred during TD stretching); MD+TD stretching+calendering (TDC);

[0085] MD only (no TD, no C): FIG. 14 is a scanning electron micrograph of the surface of an example of an MD stretched dry-processed membrane, showing that the microporous structure can be composed of aligned nucleated crystalline lamellae that connect the crystalline lamellae to each other. It has a tie chain-like structure of fibrils, and the pores have a rectangular, elongated slit shape that is characteristic of microporous membranes MD-stretched by the dry process.

[0086] A method or process for producing a MD-stretched porous polymer monolayer or multilayer membrane for a separator includes: forming a non-porous precursor membrane, layer, or material by extruding a polymer; and uniaxially stretching the non-porous membrane in MD to form an MD-stretched product, the membrane having at least one outer surface or surface layer with a slit-like pore structure, the pores being openings or spaces between adjacent lamellae, the lamellae may be connected on one or both sides by fibril or bridge structures between adjacent lamellae, at least a portion of the membrane each comprising a set of pores between adjacent lamellae, the lamellae being oriented substantially along the transverse direction, and the fibril or bridge structures between adjacent lamellae being oriented substantially along the longitudinal direction.

[0087] MD only (no TD, no C): Figure 15 is a scanning electron microscope (SEM) image of the surface of an example MD stretched dry-processed membrane, showing that the microporous structure can be composed of aligned nucleated crystalline lamellae with a tie-chain-like structure of fibrils connecting the crystalline lamellae to each other. The pores have a rectangular elongated slit shape characteristic of dry-processed MD stretched microporous membranes.

[0088] A method or process for producing a MD-stretched porous polymer monolayer or multilayer membrane for a separator includes: forming a non-porous precursor membrane, layer, or material by extruding a polymer; and uniaxially stretching the non-porous membrane in MD to form an MD-stretched product, the membrane having at least one outer surface or surface layer with a slit-like pore structure, the pores being openings or spaces between adjacent lamellae, the lamellae may be connected on one or both sides by fibril or bridge structures between adjacent lamellae, at least a portion of the membrane each comprising a set of pores between adjacent lamellae, the lamellae being oriented substantially along the transverse direction, and the fibril or bridge structures between adjacent lamellae being oriented substantially along the longitudinal direction.

[0089] MD+TD (TD with MD>MD Relaxation): A method or process for producing a biaxially stretched porous polymer monolayer or multilayer membrane for a separator includes: forming a non-porous precursor membrane, layer, or material by extruding a polymer; and sequentially and / or simultaneously biaxially stretching the non-porous membrane, layer, or material to form a MD+TD stretched porous membrane, the membrane having at least one outer surface or surface layer with a unique rounded or circular pore structure, the pores being openings or spaces between adjacent lamellae, the lamellae may be connected on one or both sides by fibril or bridge structures between adjacent lamellae, at least a portion of the membrane each containing a set of pores between adjacent lamellae, the lamellae being oriented substantially along the transverse direction and the fibril or bridge structures between adjacent lamellae being oriented substantially along the longitudinal direction (see FIG. 16).

[0090] TDC (TD>C with MD>MD Relaxation): A method or process for producing biaxially stretched and calendered porous polymer monolayer or multilayer membranes for separators includes: forming a non-porous precursor membrane, layer, or material by extruding a polymer; sequentially and / or simultaneously biaxially stretching the non-porous membrane, layer, or material to form an intermediate stretched porous membrane; and calendering the intermediate stretched porous membrane to form a biaxially stretched and calendered membrane, the membrane having at least one outer surface or surface layer with a unique pore structure, the pores being openings or spaces between adjacent lamellae, the lamellae may be connected on one or both sides by fibril or bridge structures between adjacent lamellae, at least a portion of the membrane each including a set of pores between adjacent lamellae, the lamellae being oriented substantially along the transverse direction, the fibrils between adjacent lamellae being interspersed with the fibrils or bridge structures between adjacent lamellae. The rills or bridge structures are oriented substantially along the machine direction and the outer surfaces of at least some of the lamellae are substantially flattened or planar (see FIG. 17).

[0091] In at least one embodiment, the PO-dipped membranes of the present invention, after preparation, can be laminated to other non-PO-dipped supports, which can be other MD-stretched membranes, non-woven (NW) membranes, meshes, netting, or mats such as glass mats. In this case, the PO-dipping can serve a dual function: improving strength and bonding layers together.

[0092] In at least other embodiments, the PO soak or impregnation can be a gradient or controlled soak or coating (e.g., when a PO soak is coated onto a partially pre-wetted membrane), in which case the coating only partially soaks into the membrane. For example, controlled soaking can occur when the PO soak material is a blend of two polymer resins, one of which penetrates the membrane more easily than the other (which will remain near the surface).

[0093] The membrane or separator may be a cut piece, slit, leaf, sleeve, pocket, envelope, wrap, Z-fold, serpentine, and / or the like. The membrane or separator may be a flat sheet, tape, strip, nonwoven, woven, mesh, knit, hollow fiber, and / or the like. The membrane or separator may be configured for use in electrochemical devices, batteries, cells, ESS, UPS, capacitors, supercapacitors, double layer capacitors, fuel cells (PEM, humidity control membranes, etc.), catalyst supports, supports, pancake batteries (anode, separator, cathode), substrate films, coated substrate films, textiles, barrier layers in textiles, chemical protective suits, barrier layers in chemical protective suits, blood barriers, waterproofing, filtration media, blood, blood components, blood oxygenators, disposable lighters, and / or the like.

[0094] The battery separator can be a coextruded multi-layer battery separator. Coextrusion refers to a process in which multiple polymers are simultaneously conveyed into an extrusion die, combined, and exit the die in the form of a generally planar structure in which at least two distinct layers are integrated at their interfaces, for example, by intermingling the polymers that form the interfaces of the distinct layers. The extrusion die can be either a flat sheet (or slot) die or a blown film (or annular) die. The coextrusion process will be described in more detail below. Multi-layer refers to a separator having at least two layers. Multi-layer can also refer to structures having 3, 4, 5, 6, 7, or more layers. Each layer is formed by feeding a separate polymer stream into the extrusion die. The layers can be of different thicknesses. In most cases, at least two feed streams are different polymers. Heterogeneous polymers refer to polymers with different chemical properties (e.g. PE and PP, or PE and copolymers of PE are polymers with different chemical properties); and / or polymers with the same chemical structure but different properties (e.g. two types of PE with different properties (e.g. density, molecular weight, molecular weight distribution, rheology, additives (composition and / or ratio), etc.)). However, the polymers may be the same, identical.

[0095] Polymers that can be used for the battery separator are those that are extrudable. This type of polymer is commonly referred to as a thermoplastic polymer. Exemplary thermoplastic polymers include, but are not limited to: polyolefins, polyacetals (or polyoxymethylenes), polyamides, polyesters, polysulfides, polyvinyl alcohols, Polyvinyl esters and polyvinylidene. Polyolefins include, but are not limited to: polyethylene (including, for example, LDPE, LLDPE, HDPE, UHDPE), polypropylene, polybutylene, polymethylpentane, copolymers thereof, and blends thereof. Polyamides (nylons) include, but are not limited to: polyamide 6, polyamide 66, nylon 10,10, polyphthalamide (PPA), copolymers thereof, and blends thereof. Polyesters include, but are not limited to: polyester terephthalate, polybutyl terephthalate, copolymers thereof, and blends thereof. Polysulfides include, but are not limited to: polyphenyl sulfide, copolymers thereof, and blends thereof. Polyvinyl alcohols include, but are not limited to: ethylene-vinyl alcohol, copolymers thereof, and blends thereof. Polyvinyl esters include, but are not limited to: polyvinyl acetate, ethylene vinyl acetate, copolymers thereof, and blends thereof. Polyvinylidenes include, but are not limited to: polyvinylidene fluorides (eg, polyvinylidene chloride, polyvinylidene fluoride), copolymers thereof, and blends thereof.

[0096] Various materials can be added to the polymer to modify or enhance the performance or properties of individual layers or the separator as a whole.

[0097] Materials can be added to reduce the melting temperature of the polymer. Typically, a multi-layer separator includes layers designed to close their pores at a predetermined temperature to block the flow of ions between the electrodes of the battery. This function is commonly called "shutdown". In an embodiment, a three-layer separator has a shutdown layer in the middle. To reduce the shutdown temperature of the layer, materials with a lower melting temperature than the polymer with which it is mixed can be added to the polymer. Such materials include, but are not limited to: materials with a melting temperature below 125°C, such as polyolefins or polyolefin oligomers. Such materials include, but are not limited to: polyolefin waxes (polyethylene wax, polypropylene wax, polybutene wax, and blends thereof). Such materials can be added to the polymer in a ratio of 5 to 50% by weight of the polymer. In one embodiment, a shutdown temperature below 140°C can be achieved. In another embodiment, a shutdown temperature below 130°C can be achieved.

[0098] Materials can be added to improve the melt integrity of the membrane. Melt integrity refers to the ability of the membrane to limit shrinkage or change in physical dimensions under high temperatures so that the electrodes remain physically separated. Such materials include inorganic fillers. Inorganic fillers include, but are not limited to: talc, kaolin, synthetic silica, diatomaceous earth, mica, nanoclay, boron nitride, silicon dioxide, titanium dioxide, barium sulfate, calcium carbonate, aluminum hydroxide, magnesium hydroxide, and the like, and blends thereof. Such materials can also include, but are not limited to, microfibers. Microfibers include glass fiber and chopped polymer fiber. The loading ranges from 1 to 60% by weight of the polymer of the layer. Such materials can also include high melting point or high viscosity organic materials, such as PTFE and UHMWPE. Such materials can also include crosslinking or coupling agents.

[0099] Materials can be added to improve the strength or toughness of the membrane. Such materials include elastomers, including but not limited to: ethylene-propylene (EPR), ethylene-propylene-diene (EPDM). , styrene-butadiene (SBR), styrene-isoprene (SIR), ethylidene orbomene (ENB), epoxy, and polyurethane, and blends thereof. Such materials may also include, but are not limited to, microfibers. Microfibers include chopped short polymeric fibers. Loading rates range from 2-30% by weight of the polymer of the layer. Such materials may also include crosslinking or coupling agents or high melting point materials.

[0100] Materials can be added to improve the antistatic properties of the membrane. Such materials include, for example, antistatic agents, including, but not limited to, glycerol monostearate, ethoxylated amines, polyethers (e.g., Pelestat 300, available from Sanyo Chemical Industrial, Japan). The loading is in the range of 0.001-10% by weight of the polymer of the layer.

[0101] Materials can be added to improve the wettability of the separator surface. Examples of such materials include wetting agents. Wetting agents include, but are not limited to, ethoxylated alcohols, primary polymeric carboxylic acids, glycols (e.g., polypropylene glycol and polyethylene glycol), maleic anhydride, acrylic acid, and polyolefins modified with glycidyl methacrylate. The loading is in the range of 0.01-10% by weight of the polymer of the layer.

[0102] Materials can be added to improve the surface friction performance of the separator. Examples of such materials include lubricants. Lubricants include, for example, fluoropolymers (e.g., polyvinylidene fluoride, polytetrafluoroethylene, low molecular weight fluoropolymers), slip improvers (e.g., oleamide, stearamide, erucamide, Kemamide®, calcium stearate, silicone). The loading is in the range of 0.001-10% by weight of the polymer of the layer.

[0103] Materials can be added to improve the processability of the polymer. Examples of such materials include fluoropolymers, boron nitride, and polyolefin waxes. The loadings range from 100 ppm to 10% by weight of the layer's polymer.

[0104] Materials can be added to improve the flame retardancy of the membrane, including, for example, fluorinated flame retardants, ammonium phosphate, ammonium hydroxide, alumina trihydrate, and phosphate esters.

[0105] Materials can be added to promote nucleation of the polymer. Such materials include nucleating agents, including but not limited to sodium benzoate, dibenzylidene sorbitol (DBS), and its chemical derivatives. Loading is conventional.

[0106] Materials for coloring the layer can be added. Such materials are conventional.

[0107] In the manufacture of this battery separator, polymers are co-extruded to form a multi-layer non-porous precursor, which is then processed to form the micropores. The micropores are formed by "wet" or "dry" methods. Wet methods (also called solvent extraction, phase inversion, thermally induced phase separation (TIPS), or gel extraction) generally involve: adding a removable material prior to forming the precursor, and then removing the material, for example, by an extraction method, to form the pores. Dry methods (also called the Celgard process) generally involve: extruding the precursor (without the material to be removed to form the pores) to form the micropores. forming micropores by stretching the precursor. The invention will now be described with respect to the dry process.

[0108] To impart uniform dimensional properties to the coextruded multi-layer battery separator, an extrusion die having a specific shear rate was used. It was determined that the shear rate of the die must be a minimum of 4 / sec with a throughput of 18-100 lbs / hr (8.2-45.4 Kg / hr) per layer. In one embodiment, the shear rate is 8 / sec or greater with a throughput of 18-100 lbs / hr (8.2-45.4 Kg / hr) per layer. All other parameters are conventional.

[0109] Various embodiments of the present invention have been described to fulfill various objectives of the present invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and alterations will be readily apparent to those skilled in the art that do not depart from the spirit and scope of the invention.

Claims

1. Dry-laid polymeric membranes configured to produce impregnated, coated, dip-coated, immersed, wet, soaked, filled, or treated membrane films configured for use as or in separators for lithium batteries, substrate films for coatings, filtration films or media, HVAC filters, humidity control films, membranes, laminates, or composites, PEMs or humidity control membranes in fuel cells, medical membranes or films such as transdermal patches, textiles, materials or layers of clothing, tapes, facial wipes, composite, laminates, or multilayer films , a substrate film, substrate, or precursor, the dry process polymer membrane, substrate film, substrate, or precursor comprising an impregnated, coated, dip coated, immersed, wetted, water-soaked, filled, or treated membrane film that is at least one of mesoporous (maximum average pore size of about 2.0 um to a maximum average pore size of about 10.0 um (i.e., or less)), microporous (maximum average pore size of about 10.0 nm (0.01 um) to a maximum average pore size of about 2.0 um (i.e., or less)), or nanoporous (maximum average pore size of about 10.0 nm (0.01 um)); at least one region of the pore surface of the polymeric membrane, substrate film, substrate, or precursor has thereon or therein at least a first thin layer, coating, or deposit of a first impregnate, impregnate, coat, dip coat, wet, fill, or treat material having at least a polymeric resin (B) as a major component (e.g., at an impregnation depth of at least about 10% of the thickness of the polymeric membrane); and, optionally, having thereon or therein at least one solvent residual component or other additive, agent, or filler in said impregnated, impregnated, coated, dip-coated, wetted, filled, or treated material; The polymer membrane, substrate film, substrate, or precursor may comprise: A polymer membrane, substrate film, substrate, or precursor produced by a dry process, comprising at least a polymer resin (A) as a main component, and which is at least one of porous (maximum average pore diameter of about 0.01 um to maximum average pore diameter of about 20 um), macroporous (maximum average pore diameter of more than about 10.0 um), mesoporous (maximum average pore diameter of about 2.0 um to maximum average pore diameter of about 10.0 um (i.e., equal to or less than)), or microporous (maximum average pore diameter of about 10.0 nm (0.01 um) to maximum average pore diameter of about 2.0 um (or less)).

2. 2. The dry-process polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein at least one region of the pore surface in the polymer membrane, substrate film, substrate, or precursor has at least a first thin layer, coating, or deposit of a first impregnated, impregnated, coated, dip-coated, wetting, filling, or treatment material thereon, the first thin layer, coating, or deposit having at least a polymer resin (B) as a major component (e.g., at an impregnation depth of at least about 10% of the thickness of the polymer membrane), and optionally having at least one solvent residual component or other additive, agent, or filler in the impregnated, impregnated, coated, dip-coated, wetting, filling, or treatment material thereon.

3. The polymer membrane, substrate film, substrate, or precursor according to claim 1 , wherein the resin (B) is different from the resin (A).

4. The polymer resin (B) may be used to render the coated membrane film nanoporous, microporous, mesoporous, stronger, more versatile, oleophobic, hydrophilic, exhibiting higher pin puncture strength, exhibiting higher temperature weldability, exhibiting higher oxidation resistance, etc.

2. The dry process polymer membrane, substrate film, substrate, or precursor of claim 1, which forms a thin coating that exhibits lower shutdown temperature, lower COF, lower pin pull force, higher coating adhesion, and / or functionalization, improved elongation at break, improved hole shape (round, not broken) in TMA or compression TMA testing, improved nail penetration test results (NPT pass), improved transverse direction (TD) tensile strength, improved balance of MD and TD strength properties, improved functionalization, improved ionic conductivity, shutdown, tacky (adhesive surface), ceramic coatable, IR detectable, SEM detectable, catalytic, crosslinkable, and / or other improved performance, function, and / or characteristic, and / or combinations thereof.

5. The dry-process polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein the pores of the membrane, substrate film, substrate, or precursor are subjected to a primer, a deposit, a treatment, PVD, ALD, solvent, corona, plasma, or a combination thereof before and / or after impregnation or coating with the polymer resin (B).

6. 2. The polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein the minimum pore size of the pores of the membrane, substrate film, substrate, or precursor is greater than twice the thickness of the coating of polymer resin (B), or the minimum average pore size is greater than twice the thickness of the coating of polymer resin (B).

7. 10. The dry-processed polymeric membrane, substrate film, substrate, or precursor of claim 1, wherein the coated or impregnated membrane film is at least microporous.

8. 2. The dry process polymer membrane, substrate film, substrate, or precursor of claim 1, wherein the minimum thickness of the coating of polymer resin (B) is >0.001 um.

9. 2. The dry-processed polymer membrane, substrate film, substrate, or precursor of claim 1, wherein the average thickness of the coating of polymer resin (B) is >0.01 um, or <0.10 um, or <1.0 um.

10. 2. The dry-processed polymer membrane, substrate film, substrate, or precursor of claim 1, wherein the minimum pore dimension of the pores of the polymer membrane, substrate film, substrate, or precursor is at least greater than twice the thickness of the coating of polymer resin (B), or the thickness of the coating of polymer resin (B) plus any additional coatings, treatments, deposits, and / or the like on the interior surfaces of the pores.

11. 2. The dry-processed polymer membrane, substrate film, substrate, or precursor of claim 1, wherein the minimum pore dimension of the pores in the membrane, substrate film, substrate, or precursor is at least 0.20 um.

12. 2. The dry-processed polymer membrane, substrate film, substrate, or precursor of claim 1, wherein the maximum pore dimension of the pores in the membrane, substrate film, substrate, or precursor is less than 15.0 um.

13. The minimum effective cross-sectional area of ​​at least 80% of the pores of the coated membrane, substrate film, substrate, or precursor is at least 7.85×10 per pore. -7 um 2 The claim is Item 2. A polymer membrane, a substrate film, a substrate, or a precursor according to item 1, which is produced by a dry process.

14. 2. The polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein the maximum Gurley of the coated membrane, substrate film, substrate, or precursor is 3,000 s.

15. The minimum porosity of the coated membrane, substrate film, substrate, or precursor is at least 20, or the ER is less than 3.0 Ω cm 2 or the tortuosity is less than 2.0 The polymer membrane, substrate film, substrate, or precursor according to claim 1, which is produced by a dry process.

16. The polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein the average pore size of the coated membrane, substrate film, substrate, or precursor is greater than 0.01 um, or the average pore size is less than 2.0 um.

17. 2. The dry-process polymer membrane, substrate film, substrate, or precursor of claim 1, wherein the membrane, substrate film, substrate, or precursor has circular shaped pores, or the resulting pore shape has rounded corners and smaller pore size than the pore shape of the uncoated polymer membrane, substrate film, substrate, or precursor, or the resulting pore shape is oval, ovoid, egg shaped, elliptical, rounded oval, or elongated oval.

18. The polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein the coated membrane, substrate film, substrate, or precursor is configured to be coated, polymer-coated, or ceramic-coated on at least one side thereof.

19. 2. The polymer membrane, substrate film, substrate, or precursor according to claim 1, wherein half of the pore surfaces of the membrane, substrate film, substrate, or precursor are coated or treated with the polymer resin (B) and the other half of the pore surfaces of the membrane, substrate film, substrate, or precursor are coated or treated with a polymer resin (C), the resin (C) being different from the resin (B).

20. A lithium battery comprising a battery separator comprising the polymer membrane, substrate film, substrate, or precursor produced by the dry process according to claim 1.

21. 21. A device, product, system, or vehicle comprising the lithium battery of claim 20.

22. 13. A capacitor, supercapacitor, or capacitor-battery hybrid, improved by comprising the impregnated, coated, or treated polymer membrane, substrate film, substrate, or precursor of claim 1.

23. A textile product, a garment, a wipe, a filter, a medical product, an HVAC filter, a fuel cell, a humidity control layer, or a substrate film for coating, comprising the impregnated, coated, or treated polymer membrane, substrate film, substrate, or precursor according to claim 1.

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