Porous membrane and preparation equipment thereof, and fluid classifier

Abstract

Porous membranes and apparatus for the preparation thereof, and a fluid separator (100) employing a porous membrane for fluid mass transfer and / or filtration within each different separation chamber (196, 198), the porous membrane having a porosity of 40 to 90%, an average flow pore size of at least 0.04 microns, an Aquapore pore size of at least 0.07 microns, and a cell sphericity coefficient of 0.25 to 8.0; at least part of the porous membrane is a circular microporous membrane; the thickness of the porous membrane is 8-80 microns, and the porous membrane is rolled into a cylindrical shape after being pleated; the porous membrane surrounds the outer surface of the inner cylinder (154) in the annular space (130), and turbulent flow openings (155) which are offset from each other are formed in the two axial end walls of the sorting cavity. The device can be used for filtration, mass transfer, humidity control, gas and / or liquid phase separation, selective passing of moisture, blocking of moisture in liquid and the like. The utility model has the advantages of wide application, long service life and good cost effectiveness.

Description

TECHNICAL FIELD

[0001] The utility model relates to a porous membrane, a porous membrane preparation equipment and a fluid separator using the porous membrane. The porous membrane is a longitudinal and transverse oriented porous membrane, including longitudinal and transverse oriented porous membrane multilayer composite structure, longitudinal and transverse oriented microporous membrane, longitudinal and transverse oriented macroporous membrane, battery separator, filtration medium, humidity control medium, flat sheet membrane, liquid retention medium etc.

[0002] The porous membrane according to the utility model is used for humidity control, selectively passing moisture and / or blocking moisture in liquid, is a filtration membrane, humidity control membrane, gas and / or liquid separation membrane, single-layer membrane or multilayer membrane selectively passing moisture and blocking moisture in liquid, or is a propylene-based HEPA / ULPA membrane, or battery separator. BACKGROUND

[0003] The closest prior art product to the separator of the utility model is a conventional membrane contactor, which can be used to remove entrained gas from a liquid, deaerate a liquid, filter a liquid, and add gas to a liquid, etc., to complete separation between gas / liquid, liquid / liquid, and liquid / dissolved solid. The conventional membrane contactor can force two immiscible fluid phases (liquid / liquid, gas / liquid) to contact each other to achieve separation and / or transfer of one or more components from one fluid to another. In the prior art, the membrane contactor must use a porous membrane or a microporous membrane. The structure and performance of the porous membrane determine the quality of degassing, gasification, separation, filtration, etc. However, in the prior art, the preparation process of the porous membrane has defects, resulting in various technical defects in the quality of the porous membrane; the structure of the contactor using the porous membrane is also not perfect.

[0004] US3,391,421A provides a membrane longitudinal and transverse stretching device, which has a complex structure and parts that cannot be purchased commercially, resulting in high cost.

[0005] The longitudinal traction roller pair of US4,330,499A is arranged in the transverse stretching area, and the production efficiency is low.

[0006] In US5,341,547A, the axis of each rotating roller is perpendicular to its guide rail, resulting in wrinkles on the edges of the stretched membrane.

[0007] Microporous polymer membranes are known and can be made by a variety of processes, and the process by which the membrane is made can have a substantial impact on the physical properties of the membrane. See, for example, Robert E. Kesting, Synthetic Polymeric Membranes, A Structural Perspective, Second Edition, John Wiley & Sons, New York, NY, (1985). Three different known processes for making microporous polymer membranes include: dry stretching processes (also known as CELGARD processes), wet processes, and particle stretching processes.

[0008] Dry stretching processes (CELGARD processes) refer to processes in which pore formation is caused by stretching a non-porous, semi-crystalline, extruded polymer precursor in the machine direction (MD stretching). See, for example, Kesting, supra, pages 290-297, incorporated herein by reference. This dry stretching process is different from wet processes and particle stretching processes. Typically, in wet processes, also known as phase inversion processes, extraction processes, or TIPS processes, a polymeric starting material is mixed with a processing oil (sometimes referred to as a plasticizer), the mixture is extruded, and pores are formed when the processing oil is removed (the films can be stretched before or after the oil is removed). See, for example, Kesting, supra, pages 237-286, incorporated herein by reference.

[0009] Typically, in particle stretching processes, a polymeric starting material is mixed with microparticles, the mixture is extruded, and pores are formed when the interface between the polymer and the microparticles breaks due to stretching forces during stretching. See, for example, U.S. Patent Nos. 6,057,061 and 6,080,507, incorporated herein by reference.

[0010] Furthermore, the membranes produced by these different formation processes are typically physically different, and the process by which each membrane is made typically distinguishes the membranes from one another. For example, due to stretching the precursor in the machine direction (MD), dry stretching process membranes can have slit-shaped pores (see, for example, Figure 5A , 5B , 5C). Due to the oil or plasticizer and stretching the precursor in the machine direction (MD) and the cross-machine direction or transverse direction (TD), wet process membranes tend to have more circular pores and a lace-like appearance (see, for example, Figure 5D ). In another aspect, particle stretching process membranes have elliptical pores because of the microparticles and the machine direction stretching (MD stretching) tend to form the pores (see, for example, Figure 6A ). Thus, each membrane can be distinguished from one another by its manufacturing system.

[0011] Although membranes made by dry stretching processes have met with excellent commercial success, such as a variety of CELGARD® membranes sold by Celgard, LLC of Charlotte, North Carolina, there is a continuing need for improved membranes. Dry stretched porous membranes, including flat sheet membranes, battery separators, hollow fibers, and the like, but which need to have at least selected physical properties improved, modified, or enhanced so that they can be used in a wider variety of applications, can perform better for a particular purpose, and the like.

[0012] The use of air filters to remove or reduce air pollutants such as dust, dust mites, mold, bacteria, dog dander, odors, and gases is generally known. Conventionally, air filters include a filter media formed from a piece, a cluster, or a sheet of porous material that is pleated and placed in a rectangular frame or support or folded into a wrinkled oval or cylinder so as to provide a large filtering area in a relatively small volume.

[0013] While at least some air filters have met with commercial success, there remains a need for improved filter media or filters so that they can be used in a wider variety of filtration or separation applications, can perform better for a particular purpose, and the like.

[0014] The use of porous materials to selectively pass a gas and block a liquid is known. For example, Hollow fiber membrane contactors, sold by Membrana-Charlotte, a division of Celgard, LLC of Charlotte, North Carolina, are used to vent or remove liquid bubbles. More specifically, Membrane contactors are widely used for liquid degassing in the worldwide microelectronics, pharmaceutical, energy, food, beverage, industrial, photographic, ink, and analytical markets.

[0015] Porous materials are used in filtration or separation processes. For example, various flat sheet membranes sold or marketed by Membrana GmbH of Wuppertal, Germany or by both Celgard, LLC and Daramic, LLC of Charlotte, North Carolina are used in filtration or separation processes. More specifically, such flat sheet membranes have been used to separate solid particles and liquids, to separate a gas from a liquid, to separate particles from a gas, and the like.

[0016] While at least some such porous materials used in filtration or separation processes have met with commercial success, there remains a need for improved porous materials so that they can be used in a wider variety of applications, can perform better for a particular purpose, and the like.

[0017] The use of porous materials to selectively pass moisture (water vapor) and block liquid water, liquid desiccants, or other aqueous solutions can be known. In such liquid-desiccant systems, temperature and humidity can be controlled by a salt solution (or desiccant) that absorbs or gives off water vapor.

[0018] For energy recovery ventilation systems (ERV), it is known to use porous materials that selectively pass water vapor (heat and moisture) and block gases (exhaust and intake gases), where heat and moisture are exchanged between makeup and exhaust air in the ventilation system.

[0019] For reverse osmosis desalination, it is also known to use porous materials that selectively pass pure or fresh water and block salt or saltwater, where a porous material such as a reverse osmosis filter (RO filter) allows pure water (fresh water) to pass through it, but it blocks salt. For saltwater under high pressure, fresh water is forced through the porous material and forms a fresh water stream.

[0020] For vapor desalination, it is also possible to use porous materials that selectively pass water vapor or humidity (water vapor) and block liquid saltwater, where a porous material such as a high charge density membrane can block saltwater but allow salt-free water vapor to pass through to separate saltwater and fresh water. For saltwater under high temperature, fresh water vapor is released from the saltwater, can migrate through the porous material and concentrate to form a fresh water stream.

[0021] For fuel cells such as hydrogen fuel cells that have a proton exchange membrane (PEM) that must be continuously wetted, it can be known to use porous materials that selectively pass gas or humidity (water vapor) and block liquids such as water. Waste water in the form of humidity can pass through the porous material and can be collected in a waste water holding chamber or discharged.

[0022] Although some such porous materials that can selectively pass gas or humidity (water vapor) and block liquid water or saltwater can have met with limited commercial success, such as RO membranes sold by Dow Chemical, or expanded polytetrafluoroethylene (ePTFE) membranes sold by W.L. Gore, BHA, etc., there is still a need for improved porous materials so that they can be used in a wider range of applications, can perform better for specific purposes, etc. SUMMARY

[0023] A first object of the present invention is to provide a porous membrane that has a wider range of applications, better gas / liquid phase separation performance.

[0024] A second object of the present invention is to provide a device with a porous membrane that has better gas / liquid phase separation performance.

[0025] A third object of the present invention is to provide a fluid separator that has a wider range of applications, better gas / liquid phase separation performance.

[0026] A fourth object of the present invention is to provide a system for making a porous membrane that has gas / liquid phase separation performance.

[0027] To this end, according to the first aspect of the present application, a porous membrane for fluid mass transfer and / or filtration is provided, characterized in that it has a porosity of 40% to 90%, an average flow pore size of at least 0.04 microns, an Aquapore pore size of at least 0.07 microns in size, and a sphericity coefficient of 0.25 to 8.0; at least part of the porous membrane is a circular microporous membrane; the porous membrane has a thickness of 8 microns to 80 microns, and is rolled into a cylindrical shape after being pleated. Alternatively, a porous membrane having multiple layers is provided, the layers are connected by being respectively extruded and then laminated or directly connected by co-extrusion to form an interface, without an adhesive layer, for fluid mass transfer and / or filtration, characterized in that at least one layer is a circular microporous membrane; being repeatedly folded into a Z shape, wound into a reel, pleated and folded, and / or packed into a bag; each layer has a porosity of 40% to 90%, an average flow pore size of at least 0.04 microns, an Aquapore pore size of at least 0.07 microns in size, and a sphericity coefficient of 0.25 to 8.0; the porous membrane has a thickness of 8 microns to 80 microns.

[0028] According to the second aspect of the present application, a device with a porous membrane is provided, characterized in that the porous membrane is a filtration membrane, a mass transfer membrane, a humidity control membrane, a gas and / or liquid phase separation membrane, a single / multi-layer membrane for selectively passing moisture and blocking moisture in liquid, or a propylene-based HEPA / ULPA membrane; alternatively, the device is a device for humidity control, a device for selectively passing moisture and blocking moisture in liquid, a pressure regulator, a medical device, a battery separator, or a fuel cell.

[0029] According to the third aspect of the present application, a fluid sorter is provided, characterized in that the fluid sorter has an outer cylinder and an inner cylinder; the surface of the inner cylinder has an array of holes in communication with the outer cylinder; the two ends of the outer cylinder have a left end cover and a right end cover closing the annular space between the outer cylinder and the inner cylinder, and a left inner cylinder port and a right inner cylinder port; the outer cylinder has a left outer cylinder port and a right outer cylinder port of the annular space between the outer cylinder and the inner cylinder; the outer cylinder and the inner cylinder are divided into several sorting cavities along the axial direction; in each sorting cavity, a porous membrane is wrapped around the outer surface of the inner cylinder in the annular space, and the two end walls of the sorting cavity are provided with turbulence ports offset from each other.

[0030] According to a fourth aspect of the present application, there is provided a preparation apparatus for a porous membrane, characterized in that the preparation apparatus comprises: a first device for extruding a polymer into a non-porous intermediate; and a second device for stretching the non-porous intermediate in both longitudinal and transverse directions, the second device being located downstream of the first device; the second device comprises a third device for implementing longitudinal stretching of the non-porous intermediate, and a fourth device for implementing transverse stretching of the non-porous intermediate; the fourth device comprises a fifth device that is interrelated with the third device, such that the non-porous intermediate is subjected to a proportionally limited or degree-controlled longitudinal retraction while being transversely stretched.

[0031] According to at least selected multilayer porous materials, films, membranes, laminates, co-extruded or composite materials of the present application, some improved areas can include pore shapes other than slits, round pores, increased transverse tensile strength, balance of MD and TD physical properties, high performance related to, for example, water vapor transport and hydrohead pressure, reduced Gurley, high porosity with balanced physical properties, pore structure uniformity including pore size and pore size distribution, improved durability, composites of such films with other porous materials, composites or laminates of such films, films or layers with porous nonwovens, coated films, co-extruded films, laminated films, films with desired water vapor transport (or moisture transport), hydrohead performance and physical strength properties, usefulness in more physically adverse environments without loss of desired film characteristics, combinations of film water vapor transport performance combined with macroscopic physical properties, hydrophobic, highly permeable, chemically and mechanically stable, with high tensile strength, combinations and / or similar properties.

[0032] While some films made by dry-stretching processes have met with excellent commercial success, there remains a need to improve, modify or enhance at least selected of their physical properties so that they can be used in a wider range of applications, perform better for specific purposes, etc. Some of the improved aspects of the dry-stretching process films according to the present invention can include hole shapes other than slits, round holes, increased transverse tensile strength, balance of MD and TD physical properties, high performance related to, for example, water vapor transport and head pressure, reduced Gurley, high porosity with balanced physical properties, hole structure uniformity including hole size and hole size distribution, increased durability, composites of this film with other porous materials, composites or laminates of this film, membrane or layer with porous nonwovens, coated films, co-extruded films, laminated films, films with desired water vapor transport (or moisture transport), head performance and physical strength properties, useful in more physically adverse environments without loss of desired film characteristics, combinations of film water vapor transport performance coupled with macroscopic physical properties, hydrophobic, highly permeable, chemically and mechanically stable, with high tensile strength, combinations and / or similar properties.

[0033] According to at least selected potentially preferred embodiments, the porous film of the present invention can preferably be a dry-stretching process porous film, membrane, layer, or a composite that is hydrophobic, highly permeable, chemically and mechanically stable, with high tensile strength, and combinations thereof. These properties appear to make it an ideal membrane or film for use in the following applications, each of which (except for air filtration) can involve selective passage of moisture (or other gas) and blocking of liquid water (or other liquid): 1. HVAC: a. Liquid-desiccant (LD) air conditioning (temperature and humidity control), b. Water-based air conditioning (temperature and humidity control), c. Energy recovery ventilation systems (ERV); 2. Desalination: vapor desalination applications; 3. Fuel cells: humidification units; 4. Liquid and / or air filtration: filters

[0034] Particularly in the case of liquid and air filtration, the unique hole structure of the present invention can provide embodiments, materials or films that have some specific benefits such as durability, high efficiency, narrow hole size distribution and uniform flow rates.

[0035] According to the present application, at least one selected porous monolayer or multilayer polymeric film has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected film can also have a high porosity (>60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected film or membrane can be produced integrally with or laminated to a porous support material or layer, such as a nonwoven material on one or both sides thereof. The resulting composite, film or product can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected films and composite products are unique in the combination of their macro physical properties combined with their film water vapor transport performance. For example, existing films can already have porosity, but not sufficient hydrohead pressure or performance, other films are too fragile, other films are robust but lack other properties, etc., while the present application can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0036] According to the present application, at least one selected porous monolayer polyolefin (PO) such as polypropylene or polyethylene (monolayer PP or PE) film has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected monolayer PO film can also have a high porosity (>60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected monolayer PO film or membrane can be produced integrally with or laminated to a porous support or material, such as a polypropylene (PP) nonwoven material (nonwoven PP) on one or both sides thereof. The resulting composite, film or product can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected monolayer PP films and composite products are unique in the combination of their macro physical properties combined with their film water vapor transport performance. For example, existing films can already have porosity, but not sufficient hydrohead pressure or performance, other films are too fragile, other films are robust but lack other properties, etc., but the present application can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0037] According to the present application, at least one selected porous multi-layer polyolefin (PO) film, such as a polypropylene (PP) and / or polyethylene (PE) multi-layer film (multi-layer PP and / or PE), has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected multi-layer PO film can also have a high porosity (> 60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected multi-layer PO film or membrane can be produced integrally with or laminated to a porous support or material, such as a polypropylene (PP) nonwoven material (nonwoven PP) on one or both sides thereof. The resulting composite, film or product can preferably maintain excellent water vapor transport and even more improved hydrohead performance, can have physical strength properties far exceeding comparative films, can have additional advantages useful in more physically adverse environments without losing highly desirable film characteristics, can have a unique combination of film water vapor transport performance coupled with macro physical properties, and can have, for example, desirable porosity, water vapor transport, hydrohead pressure, strength, etc.

[0038] According to the present application, at least one selected porous multi-layer polyolefin (PO) film, such as a polypropylene (PP) and / or polyethylene (PE) multi-layer film (multi-layer PP and / or PE), has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected multi-layer PO film can also have a high porosity (> 60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected multi-layer PO film or membrane can be produced integrally with or laminated to a porous support or material, such as a polypropylene (PP) nonwoven material (nonwoven PP) on one or both sides thereof. The resulting composite, film or product can preferably maintain excellent water vapor transport and even more improved hydrohead performance, can have physical strength properties far exceeding comparative films, can have additional advantages useful in more physically adverse environments without losing highly desirable film characteristics, can have a unique combination of film water vapor transport performance coupled with macro physical properties, and can have, for example, desirable porosity, water vapor transport, hydrohead pressure, strength, etc.

[0039] According to the present application, at least one selected porous multi-layer polymeric film, for example, a multi-layer (two or more layers) polyolefin (PO) film, such as a polypropylene (PP) and / or polyethylene (PE) (including PE, PP or PE+PP blend) multi-layer film, has excellent MD and TD physical property balance, while also being a high performance film, as measured by water vapor transport (or moisture vapor transport) and hydrohead performance. The selected multi-layer polymeric film can also have high porosity (>60%), but still maintain balanced physical properties when compared to more conventional films. At the same time, the selected multi-layer polymeric film or film can be co-produced with or laminated to a porous support or material, such as a PO nonwoven material [such as a porous polyethylene (PE) nonwoven (nonwoven PE) and / or a porous polypropylene (PP) nonwoven (nonwoven PP)] on one or both sides thereof. The resulting composite, film or product can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product can have the added advantage of being useful in more physically adverse environments without losing the high desirable film features. It is believed that these selected multi-layer polymeric films and composite products are unique in their combination of film water vapor transport performance coupled with their macroscopic physical properties. The present application can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0040] According to the present application, the pores (openings) have the following pore aspect ratio [based on the physical dimensions of the pore openings in the machine direction (MD) (length) and the transverse direction (TD) (width), by measuring one or more pores (preferably some pores to determine an average) in a SEM of the surface, top or front face (A side) of the selected film or composite, for example, a single layer, double layer or triple layer film]: a typical range of MD / TD aspect ratio of 0.75 to 1.50, a preferred range of MD / TD aspect ratio of 0.75 to 1.25, a more preferred range of MD / TD aspect ratio of 0.85 to 1.25.

[0041] According to at least selected porous material or porous membrane embodiments of the present application, if the MD / TD aspect ratio of the pores is 1.0, the three-dimensional or 3D pore sphericity coefficient or ratio (MD / TD / ND) can range from: 1.0 to 8.0 or more; possibly preferred 1.0 to 2.5; and most possibly preferred 1.0 to 2.0 or less [based on the physical dimensions of the pore openings in the machine direction (MD) (length), transverse direction (TD) (width), and thickness direction or cross-section (ND) (thickness); for example, measure the MD and TD of one or more pores (preferably some pores to determine an average) in the SEM at the surface, top or front (A-side), or surface, bottom or back (B-side), and measure the ND of one or more pores (preferably some pores to determine an average) in the SEM at the cross-section, depth or height (C-side) (length or width cross-section or both) (the ND dimension can have different pores compared to the MD and TD dimensions as it can be difficult to measure the ND, MD and TD dimensions of the same pore)].

[0042] According to the present application, the pores (openings) have the following three-dimensional or 3D pore sphericity coefficient or ratio [based on the physical dimensions of the pore openings in the machine direction (MD) (length), transverse direction (TD) (width), and thickness direction or cross-section (ND) (thickness); for example, measure one or more pores (preferably some pores to determine an average) in the SEM at the surface, top or front (A-side), surface, bottom or back (B-side), and cross-section, depth or height (C-side) (length or width cross-section or both) of the selected membrane, layer or composite material, such as the selected single and three layer membranes (the ND dimension can have different pores compared to the MD and TD dimensions as it can be difficult to measure the ND, MD and TD dimensions of the same pore)], for example: a typical range of 0.75 to 1.50 MD / TD aspect ratio, a range of 0.50 to 7.50 MD / ND dimension ratio, a range of 0.50 to 5.00 TD / ND dimension ratio; a preferred range of 0.75 to 1.25 MD / TD aspect ratio, a range of 1.0 to 2.5 MD / ND dimension ratio, a range of 1.0 to 2.5 TD / ND dimension ratio; a more preferred range of 0.85 to 1.25 MD / TD aspect ratio, a range of 1.0 to 2.0 MD / ND dimension ratio, a range of 1.0 to 2.0 TD / ND dimension ratio.

[0043] According to the present application, the pores (openings) have the following three-dimensional or 3D pore sphericity coefficient or ratio [based on the physical dimensions of the pore openings in the machine direction (MD) (length), transverse direction (TD) (width), and thickness direction or cross-section (ND) (thickness); for example, measure one or more pores (preferably some pores to determine an average) in the SEM at the surface, top or front (A-side), surface, bottom or back (B-side), and cross-section, depth or height (C-side) (length or width cross-section or both) of the selected membrane, layer or composite material, such as the selected single and three layer membranes (the ND dimension can have different pores compared to the MD and TD dimensions as it can be difficult to measure the ND, MD and TD dimensions of the same pore)], for example: a typical range of 0.75 to 1.50 MD / TD aspect ratio, a range of 0.50 to 7.50 MD / ND dimension ratio, a range of 0.50 to 5.00 TD / ND dimension ratio; a preferred range of 0.75 to 1.25 MD / TD aspect ratio, a range of 1.0 to 2.5 MD / ND dimension ratio, a range of 1.0 to 2.5 TD / ND dimension ratio; a more preferred range of 0.85 to 1.25 MD / TD aspect ratio, a range of 1.0 to 2.0 MD / ND dimension ratio, a range of 1.0 to 2.0 TD / ND dimension ratio.

[0044] According to the present application, the holes (openings) have the following hole sphericity coefficients or ratios [based on the physical dimensions of the hole openings in the machine direction (MD) (length), transverse direction (TD) (width), and thickness direction or cross-section (ND) (thickness)] based on the measurement of the holes in the SEM of the top or front (A-side) and length and cross-section (C-side) of selected monolayer and trilayer films: the typical numbers for the range of sphericity coefficients or ratios for the machine direction MD (length), transverse direction TD (width), and thickness direction ND (perpendicular height) are: MD / TD aspect ratio ranging from 0.75 to 1.50, MD / ND size ratio ranging from 0.50 to 7.50, TD / ND size ratio ranging from 0.50 to 5.00.

[0045] According to the present application, the microporous films are made by a dry stretching process and have substantially circular holes and a ratio of the machine direction tensile strength to the transverse direction tensile strength ranging from 0.5 to 6.0, preferably 0.5 to 5.0. The system for making the foregoing microporous films includes the steps of extruding a polymer as a non-porous precursor, and stretching the non-porous precursor in the machine direction and the transverse direction, the transverse direction stretching including simultaneous controlled machine direction relaxation.

[0046] According to the present application, the microporous films are made by a dry stretching process and have substantially circular holes and a ratio of the machine direction tensile strength to the transverse direction tensile strength ranging from 0.5 to 6.0, preferably 0.5 to 5.0. The system for making the foregoing microporous films includes the steps of extruding a polymer as a non-porous precursor, and stretching the non-porous precursor in the machine direction and the transverse direction, the transverse direction stretching including simultaneous controlled machine direction relaxation.

[0047] While some films made by conventional dry stretching processes have met with great commercial success, the present application provides improved, modified, or enhanced at least selected physical properties so that they can be used in a wider range of applications, perform better for specific purposes, and the like.

[0048] While at least some air filters have met with commercial success, improved, modified, or enhanced filtration media are provided according to the present application so that they can be used in a wider range of filtration or separation applications, perform better for specific purposes, and the like.

[0049] While at least some flat sheet porous materials for filtration or separation processes have met with commercial success, improved, modified, or enhanced porous materials are provided according to the present application so that they can be used in a wider range of applications, perform better for specific purposes, and the like.

[0050] While some porous materials for selectively passing gas or moisture (water vapor) and blocking liquid water or brine can have met with commercial success, such as RO membranes sold by Dow Chemical, ePTFE membranes sold by W.L. Gore, BHA, etc., improved, modified, or enhanced porous materials are provided according to the present invention so that they can be used for a wider range of applications, perform better for specific purposes, etc.

[0051] According to the present invention, an air filter cartridge includes at least one pleated porous membrane, such as a microporous membrane.

[0052] The present invention can be used for filtration, mass transfer, humidity control, gas and / or liquid phase separation, selective passage of moisture and blocking of liquid water, etc.

[0053] The present invention is widely used, has a long service life, and is cost effective.

[0054] Relative to US 3,391,421 A, the present invention provides an automated longitudinal and transverse stretching apparatus for membranes, in which all the various electronic controllers are commercially available, resulting in a simplified apparatus structure, a significantly reduced number of parts, high reliability, and the ability to produce high-quality products.

[0055] Unlike US 4,330,499 A, in the present invention, the longitudinal traction roller pair for moderately relaxing the previously elongated membrane is disposed at the most downstream end of the automated longitudinal and transverse stretching apparatus, rather than in the transverse stretching area, so that the controlled retraction rate can be significantly increased to 80%, and the production efficiency is also high.

[0056] In contrast to US 5,341,547 A, in the present invention, the axes of the various rotating rollers are perpendicular to the longitudinal stretching direction, rather than perpendicular to the guide rails, so that the edges of the stretched membrane are no longer wrinkled. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is a schematic diagram of the internal structure and principle of a porous membrane contactor according to the present invention.

[0058] Figure 2 is a schematic diagram of the structure and principle of a longitudinal and transverse stretching device for porous membranes according to the present invention.

[0059] Figure 3 is a schematic diagram of the structure and principle of a longitudinal and transverse stretching device for porous membranes according to the present invention as shown in Figure 2 .

[0060] Figure 4A , Figure 4B , Figure 4C , Figure 4D , Figure 4Eare respectively first state, second state, third state, fourth state, fifth state schematic diagram of the porous membrane longitudinal and transverse stretching device according to the utility model.

[0061] Figure 5A are Photo of single layer, conventional dry-stretch, polypropylene, battery separator (SEM surface microscope photo).

[0062] Figure 5B Photo of prior art dry-stretch film (single layer sheet film).

[0063] Figure 5C Photo of prior art dry-stretch film (multi-layer sheet film, sheet lamination followed by stretching).

[0064] Figure 5D are Photo of single layer, wet process, polyethylene battery separator (SEM surface microscope photo).

[0065] Figure 6A Photo of granular stretched film (SEM surface microscope photo).

[0066] Figure 6B Photo of granular stretched film (SEM cross-section microscope photo).

[0067] Figure 7A Photo of film according to one embodiment of the utility model (single layer sheet film, longitudinal and transverse orientation process) (SEM surface microscope photo).

[0068] Figure 7B Photo of film according to another embodiment of the utility model (multi-layer sheet film, sheet lamination together followed by stretching, longitudinal and transverse orientation process) (SEM surface microscope photo).

[0069] Figure 8 Photo of film according to yet another embodiment of the utility model (multi-layer sheet film, sheet co-extrusion followed by stretching, longitudinal and transverse orientation process) (SEM surface microscope photo).

[0070] Figure 9 Schematic diagram of exemplary TD stretching process according to at least one embodiment of the longitudinal and transverse orientation film manufacturing system of the utility model.

[0071] Figure 10 Photo of conventional 2500 film (PP single layer, dry-stretch process) at 20,000X magnification (SEM surface microscope photo).

[0072] Figure 11 Photo of Figure 10Photo of film (SEM surface microscope photo).

[0073] Figure 12 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface A (top) microscope photo at 20,000X and 5,000X magnification), pore size 0.3-0.6 microns, average aspect ratio about 1.0. Figure 10 and 11 Photo of film (SEM cross-section microscope photo).

[0074] Figure 13 and Figure 14 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification).

[0075] Figure 15 and Figure 16 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification). Figure 13 and Figure 14 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification).

[0076] Figure 17 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification). Figures 13-16 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification).

[0077] Figure 18 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification). Figures 13-16 Photo of film sample B (PP monolayer, bubble broken, longitudinal and transverse orientation process) according to another film embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X and 5,000X magnification).

[0078] Figure 19 , Figure 20 and Figure 21 Photo of film sample C (PP monolayer / nonwoven PP, laminated [heat + pressure]) according to yet another film or composite material embodiment of the present application (SEM surface A (top) microscope photo at 20,000X, 5,000X and 1,000X magnification), pore size 0.3-0.6 microns, average aspect ratio about 1.0.

[0079] Figure 22 , Figure 23 and Figure 24 Photo of film sample C (PP monolayer / nonwoven PP, laminated [heat + pressure]) according to yet another film or composite material embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X, 5,000X and 1,000X magnification). Figures 19-21 Photo of film sample C (PP monolayer / nonwoven PP, laminated [heat + pressure]) according to yet another film or composite material embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X, 5,000X and 1,000X magnification).

[0080] Figure 25 and Figure 26 Photo of film sample C (PP monolayer / nonwoven PP, laminated [heat + pressure]) according to yet another film or composite material embodiment of the present application (SEM surface B (bottom) microscope photo at 20,000X, 5,000X and 1,000X magnification). Figures 19-24Various photographs of film sample C (SEM cross-section microscope photographs at 20,000X and 5,000X magnification).

[0081] Figure 27 Film sample C with nonwoven PP layer on top Figures 19-26 Photograph of film sample C (SEM cross-section microscope photograph at 615X magnification) (inverted).

[0082] Figure 27A Film sample C with Figure 27 Photograph of single layer PP layer portion of film sample C (SEM cross-section microscope photograph at 3,420X magnification) (note Figure 27 rectangle in).

[0083] Figure 28 Film sample A (single layer PP, foam not broken, longitudinal and transverse orientation process) Figure 29 Various photographs of film sample A (SEM surface A (top) microscope photographs at 20,000X and 5,000X magnification), aperture size 0.3-0.7 microns, average aspect ratio approximately 1.0, according to yet another film embodiment of the present application (single layer PP, foam not broken, longitudinal and transverse orientation process).

[0084] Figure 30 Film sample A Figure 31 Various photographs of film sample A (SEM surface B (bottom) microscope photographs at 20,000X and 5,000X magnification), aperture size 0.3-0.7 microns, average aspect ratio approximately 1.0. Figure 28 29 Film sample G (PP single layer [of sample A], foam not broken, longitudinal and transverse orientation process / nonwoven PP, laminated [heat + pressure])

[0085] Figure 32 Figure 33 Various photographs of film or composite sample G (PP single layer [of sample A], foam not broken, longitudinal and transverse orientation process / nonwoven PP, laminated [heat + pressure]) according to another embodiment of the present application (SEM surface A (top) microscope photographs at 20,000X, 5,000X and 1,000X magnification), aperture size 0.3-0.6 microns, average aspect ratio approximately 1.0-1.10. Figure 34

[0086] Film sample G Figure 35 Various photographs of film sample G (SEM surface B (bottom) microscope photographs at 20,000X, 5,000X and 1,000X magnification). Figure 36 Figure 37 Figures 32-34

[0087] Figure 38 Film sample G Figure 39 Various photographs of film sample G (SEM surface B (bottom) microscope photographs at 20,000X, 5,000X and 1,000X magnification). Figures 32-37 ​​​​Various photographs of membrane sample G (SEM cross-sectional micrographs at 20,000X and 3,420X magnification).

[0088] Figure 40 It has a non-woven PP layer on top. Figures 32-39 Photograph of membrane sample G (SEM cross-sectional micrograph at 615X magnification) (inverted).

[0089] Figure 40A for Figure 40 A photograph of a portion of the monolayer PP layer of membrane sample G (SEM cross-sectional micrograph at 3,420X magnification) (Note) Figure 40 (The rectangle in the middle).

[0090] Figure 41 The image shows a SEM surface A (top) micrograph of a membrane sample E (PP monolayer, foam broken, longitudinal and transverse orientation process) at 20,000X magnification according to another membrane embodiment of the present invention. The pore size is 0.3-0.7 micrometers and the average aspect ratio is about 1.0.

[0091] Figure 42 The image shows a SEM surface A (top) image of a membrane sample E (PP monolayer, foam broken, longitudinal and transverse orientation process) according to another membrane embodiment of the present invention at a magnification of 5,000X. The pore size is 0.3-0.7 micrometers and the average aspect ratio is about 1.0.

[0092] Figure 43 for Figure 41 SEM image of the surface B (bottom) of membrane sample E at 20,000X magnification.

[0093] Figure 44 for Figure 42 SEM image of the membrane sample E at 5,000X magnification, showing the surface B (bottom).

[0094] Figure 45 for Figure 43 A cross-sectional micrograph of membrane sample E at 20,000X magnification using SEM.

[0095] Figure 46 for Figure 44 A cross-sectional micrograph of the membrane sample E at 5,000X magnification using SEM.

[0096] Figure 47 The image shows a SEM surface A (top) image of a membrane sample F (single-layer PP, unbroken foam, longitudinal and transverse orientation process) according to another membrane embodiment of the present invention at a magnification of 20,000X. The pore size is 0.4-1.0 micrometers and the average aspect ratio is about 1.1.

[0097] Figure 48 SEM surface A (top) micrograph of film sample F (single layer PP, bubble not broken, machine direction and transverse orientation process) at 5,000X magnification according to yet another film embodiment of the present application.

[0098] Figure 49 SEM surface B (bottom) micrograph of film sample F at 20,000X magnification. Figure 47

[0099] SEM surface B (bottom) micrograph of film sample F at 5,000X magnification. Figure 50 Figure 48 SEM surface A (top) micrograph of film sample D (co-extruded PP / PE / PP three layers, bubble broken, machine direction and transverse orientation process) at 20,000X magnification according to yet another film embodiment of the present application.

[0100] Figure 51 SEM surface A (top) micrograph of film sample D (co-extruded PP / PE / PP three layers, bubble broken, machine direction and transverse orientation process) at 5,000X magnification according to yet another film embodiment of the present application.

[0101] Figure 52 SEM surface B (bottom) micrograph of film sample D at 20,000X magnification.

[0102] Figure 53 Figure 51 SEM surface B (bottom) micrograph of film sample D at 5,000X magnification.

[0103] Figure 54 SEM surface B (bottom) micrograph of film sample D at 5,000X magnification. Figure 52 DETAILED DESCRIPTION

[0104] In the present application, the term "circular porous membrane" means a membrane having substantially circular pores with a sphericity coefficient of about 0.25 to 8.0, a porosity of 40% to 90%, a ratio of machine direction tensile strength to transverse tensile strength of 0.5 to 5.0, a JIS Gurley permeability of less than 100 seconds, an average flow pore size of at least 0.04 microns, an Aquapore pore size of at least 0.07 microns, and a hydrohead pressure of greater than 140 psi.

[0105] ​​​The circular microporous membrane is made by a dry stretching process comprising the steps of: extruding a polymer into at least a single layer of non-porous precursor; then, stretching the non-porous precursor in the machine direction and in the cross direction, the cross direction stretching comprising simultaneous controlled machine direction relaxation; or the machine direction and cross direction stretching comprising simultaneous cross direction stretching and machine direction stretching; or the machine direction and cross direction stretching comprising machine direction stretching and simultaneous controlled cross direction relaxation; or the machine direction and cross direction stretching comprising machine direction stretching and thereafter the cross direction stretching simultaneous with controlled machine direction relaxation, a second cross direction stretching simultaneous with machine direction stretching and subsequent cross direction relaxation, machine direction stretching to form a porous intermediate prior to the cross direction stretching; or the machine direction and cross direction stretching comprising machine direction stretching, additional cross direction stretching simultaneous with machine direction stretching, and cross direction relaxation; or simultaneously stretching a plurality of separate, superimposed, layers or plies of the non-porous precursor in the machine and cross directions, wherein at least one of: none of the plies are bonded together during the stretching process and all of the plies are bonded together during the stretching process.

[0106] The porous membrane has the following material properties: a thickness of at least about 8 microns to 80 microns, a cross direction tensile strength of at least about 300 kgf / cm 2 , a standard deviation of the mean flow pore size of less than about 0.025, a hydrohead pressure of at least about 80 psi, and a WVTR of at least about 8,000 g / m 2 · day; a cross direction shrinkage of less than about 1.0% at 90°C, less than about 1.5% at 105°C and / or less than 3.0% at 120°C; a porosity of 65% to 90%, a ratio of the machine direction tensile strength to the cross direction tensile strength of about 1.0 to 5.0, a JIS Gurley permeability of less than about 20 seconds, a mean flow pore size of at least about 0.05 microns, an Aquapore pore size of at least about 0.08 microns, and a hydrohead pressure of greater than about 145 psi.

[0107] The non-porous precursor is a single layer precursor formed by single layer extrusion using a blown die / slit die or a multi-layer precursor formed by co-extrusion / single layer extrusion followed by lamination. The porous membrane includes at least one non-woven layer, woven layer or braided layer.

[0108] The polymer is selected from the group consisting of polyolefins, fluorocarbons, polyamides, polyesters, polyacetals, polyformaldehydes, polysulfides, polyphenylene sulfides, polyvinyl alcohols, copolymers, mixtures, or combinations thereof. The substantially circular pores have an aspect ratio of about 0.75 to 1.25 or a sphericity coefficient of about 0.25 to 8.0.

[0109] Figure 1In the drawings, reference numeral 100 represents a porous membrane sorter; reference numeral 110 represents a cylindrical housing; reference numeral 112 represents a center port; reference numeral 113 represents a left inner cylinder port, reference numeral 114 represents a center port, right inner cylinder port; reference numeral 116 represents a left end cap; reference numeral 118 represents a right end cap; reference numeral 120 represents an end cap lock; reference numeral 122 represents an end cap lock; reference numeral 124 represents a left outer cylinder port; reference numeral 126 represents a right outer cylinder port; reference numeral 130 represents a porous membrane; reference numeral 132 represents a housing center section; reference numeral 138 represents an encapsulant; reference numeral 140 represents an encapsulant; reference numeral 146 represents an end; reference numeral 148 represents an end; reference numeral 153 represents a flange; reference numeral 154 represents an inner tube; reference numeral 155 represents a radial spoiler; reference numeral 156 represents a circumferential porous membrane; reference numeral 166 represents a flared end; reference numeral 168 represents a flared end; reference numeral 186 represents a retaining clip; reference numeral 190 represents a perforated inner tube; reference numeral 192 represents a perforated inner tube; reference numeral 194 represents a block for forced flow reversal; reference numeral 196 represents a sorting chamber; reference numeral 198 represents a sorting chamber.

[0110] According to one embodiment, if a first liquid to be degassed is flowed through the porous membrane sorter 100 from the end port 112 to the end port, right inner cylinder port 114, the liquid first flows through the left inner cylinder port 113 in the end port 112, through the openings in the spoiler 190 and out the circumferential porous membrane 156, around the axial porous membrane sorting chamber 196 over the radial spoiler 155, around the axial porous membrane sorting chamber 198 through the circumferential porous membrane 156 and out the openings in the perforated inner tube 192, out through the center port, right inner cylinder port 114. The perforated inner tube 190 is a liquid distribution tube and the perforated inner tube 192 is a liquid collection tube.

[0111] According to one embodiment, if a first liquid to be degassed is flowed through the porous membrane sorter 100 from the end port 112 to the end port, right inner cylinder port 114, the liquid first flows through the left inner cylinder port 113 in the end port 112, through the openings in the spoiler 190 and out the circumferential porous membrane 156, around the axial porous membrane sorting chamber 196 over the radial spoiler 155, around the axial porous membrane sorting chamber 198 through the circumferential porous membrane 156 and out the openings in the perforated inner tube 192, out through the center port, right inner cylinder port 114. The perforated inner tube 190 is a liquid distribution tube and the perforated inner tube 192 is a liquid collection tube.

[0112] In the housing 110 of the porous membrane fractionator 100, only a single radial spoiler 155 is shown, but two or more radial spoilers can be used, or no radial spoiler can be provided. The spoiler 155 can be located only in the annular space between the inner and outer tubes, or can be the entire cross section within the outer tube.

[0113] The utility model discloses a more advanced longitudinal and transverse stretching automatic equipment, and the controlled retraction rate can be up to 80%, and the high-quality product of more extensive use can be manufactured, and the reliability is high, and the service life is long, and the investment benefit ratio is also high.

[0114] According to one embodiment of the utility model, as Figures 2-3 As shown in the figure, a kind of manufacturing equipment of microporous membrane is provided, and it is characterized in that, the manufacturing equipment includes: first device 10 (commercially available in prior art) for extruding or extruding polymer into non-porous intermediate body;And the second device 20 for longitudinal and transverse stretching of the non-porous intermediate body.

[0115] "Longitudinal and transverse stretching" refers to stretching in both longitude and latitude, i.e. stretching in both longitudinal direction (machine direction) and transverse direction.

[0116] The second device 20 is located downstream of the first device 10 with respect to the direction of product line shown by arrow X.

[0117] The second device 20 includes third device 30 for implementing longitudinal stretching of the non-porous intermediate body, and fourth device 40 for implementing transverse stretching of the non-porous intermediate body.

[0118] The fourth device 30 includes fifth device 50 associated with third device 30, so that the non-porous intermediate body is subjected to limited proportion or controlled degree of longitudinal retraction (in the opposite direction of arrow X) while being transversely stretched.

[0119] For example, the fourth device 40 includes a series of mutually parallel transverse rollers, i.e. a pair of first rotating rollers 41 arranged transversely for initially clamping the side edges of the non-porous intermediate body being stretched, a plurality of pairs of second rotating rollers 42 arranged transversely for clamping the side edges of the non-porous intermediate body being stretched, and a pair of third rotating rollers 43 arranged transversely for releasing the clamping of the side edges of the non-porous intermediate body being stretched.

[0120] The fourth device 40 includes fifth device 50 for achieving the transverse stretching and longitudinal retraction of the film intermediate body being simultaneously stretched in two directions. A proportion controller 45 (commercially available in prior art) is provided between the fourth device 40 and the fifth device 50; the fifth device 50 allows the film being transversely stretched to be limited proportionally or controlled degree in longitudinal direction, according to predetermined proportion or size, under the action of the proportion controller 45.

[0121] The third device 30 is a pair of rollers 30 driven to rotate at a speed VI, and the fifth device 50 is another pair of rollers with the same radius as the third device 30, driven to rotate at a speed V2, V2 < VI; in this way, at the region 60, the film pair that has been longitudinally stretched is proportionally retracted while being transversely stretched.

[0122] The elements in the stretching can use parts available in the prior art. In an embodiment of the present application, two pairs of traction rollers 30, 50 with the same radius are used, wherein the second roller pair 50 rotates at a speed V2 lower than the rotation speed of the first roller pair 30. For example, if it is desired to have a 10% retraction while being transversely stretched, the second roller pair 50 can be driven so that its rotation speed V2 is 90% of the rotation speed of the first roller pair 30.

[0123] In the above embodiment, between the first device 10 and the second device 20, the non-porous intermediate passage section 15 can not be provided; or, by opening the non-porous intermediate passage controller 14, the provided non-porous intermediate passage section 15 is not in operation, so that enough space is reserved between the passage roller pairs 12 with axes perpendicular to the stretching direction X to be out of contact with the non-porous intermediate section 11. In such a working condition, the film is longitudinally stretched under the action of the roller pairs 30, 50, and is simultaneously stretched on both sides under the action of the pair of transversely arranged first rotating rollers 41, the at least one pair of transversely arranged second rotating rollers 42, and the pair of transversely arranged third rotating rollers 43.

[0124] Alternatively, between the first device 10 and the second device 20, the non-porous intermediate passage section 15 is provided, which is provided with the non-porous intermediate passage controller 14 having an open state and a closed state. In the open state, the passage rollers 12 with axes perpendicular to the stretching direction X are out of contact with the non-porous intermediate section 11; in the closed state, the passage rollers 12 clamp the two side edges of the non-porous intermediate section 11.

[0125] In another embodiment, the intermediate passage controller 14 remains in the closed state, the non-porous intermediate passage section 15 starts to work, and the passage roller pairs 12 with axes perpendicular to the stretching direction X abut against each other to clamp the two side edges of the non-porous intermediate section 11. In such a working condition, the film is first longitudinally stretched under the action of the roller pairs 30, 50, and then is subsequently stretched on both sides under the action of the pair of transversely arranged first rotating rollers 41, the at least one pair of transversely arranged second rotating rollers 42, and the pair of transversely arranged third rotating rollers 43.

[0126] The first rotating rollers 41 and the third rotating rollers 43 are coordinated in reverse operation by a reverser 44 (commercially available in the prior art), i.e. when the third rotating rollers 43 start to move away from each other, the first rotating rollers 41 enter the state of abutting against each other, and when the first rotating rollers 41 start to clamp the film in elongation, the third rotating rollers 43 start to move away from each other.

[0127] As shown in Figure 4A , 4B , 4C, 4D and 4E, the first rotating rollers 41, the second rotating rollers 42 and the third rotating rollers 43 are driven to clamp the side edges of the holeless intermediate body in elongation with the full length of the first rotating rollers 41, the second rotating rollers 42 and the third rotating rollers 43; the second rotating rollers 42 keep clamping the side edges of the holeless intermediate body in elongation by means of an electronic brake controller 46 (commercially available in the prior art). Under the monitoring of the electronic brake controller 46, when no film passes through a certain second rotating roller 42, a gap is kept between the second rotating roller 42; on the contrary, when it is detected that a film passes through a certain second rotating roller 42, the second rotating roller 42 abuts against each other immediately, clamps the side edges of the holeless intermediate body in elongation, and keeps in this state.

[0128] Based on the embodiment as shown in Figures 2-3 , the utility model has many variant embodiments.

[0129] In another embodiment, the roller pairs 30, 50 can be arranged at positions between the two guide rails 40, or even the roller pairs 30 are arranged at the area 11, so as to further enhance the "simultaneous" transverse stretching (by the first rotating rollers 41 arranged in the transverse direction, the second rotating rollers 42 arranged in the transverse direction, and the third rotating rollers 43 arranged in the transverse direction) during the longitudinal stretching (by the roller pairs 30, 50).

[0130] The axes of the first rotating rollers 41, the second rotating rollers 42 and the third rotating rollers 43 are all perpendicular to the stretching direction X, and are arranged at an acute angle with the fourth device, i.e. the guide rail 40.

[0131] In yet another embodiment, the roller pairs 30, 50 can be divided into a left roller pair group and a right roller pair group, the left roller pair group is arranged in the left guide rail, and the right roller pair group is arranged in the right guide rail.

[0132] In particular, the third device 30 and the fifth device 50 are cancelled, and their functions are replaced by the first transversely arranged rotating roller 41, the second transversely arranged rotating roller 42, and the third transversely arranged rotating roller 43; the first rotating roller 41 and / or at least one second rotating roller 42 are driven to rotate at a speed V3, and the third rotating roller 43 is driven to rotate at a speed V4, V4 < V3. The first rotating roller 41 and the one or more second rotating rollers 42 can replace the roller pair 30 and play the same role as the roller pair 30, and the third rotating roller 43 can replace the roller pair 50 and play the same role as the roller pair 50.

[0133] In other embodiments of the manufacturing equipment according to the present application, between the first device 10 and the second device 20, a sixth device for annealing the non-porous intermediate after being extruded and before being stretched longitudinally and transversely is further provided, preferably, the annealing is performed at a temperature in the range of T m -80℃ to T m -10℃. In other embodiments of the manufacturing equipment according to the present application, the third device is provided with a seventh device for controlling the stretching temperature, so that the longitudinal stretching is performed by hot longitudinal stretching (at a temperature of < T m -10℃) or by cold longitudinal stretching (at a temperature of < T m -50℃), or both.

[0134] In other embodiments of the manufacturing equipment according to the present application, the third device is provided with an eighth device for controlling the longitudinal stretching range, so that the total longitudinal stretching is 50-500%; the fourth device is provided with a ninth device for controlling the transverse stretching range, so that the total transverse stretching is 100-1200%; and the fifth device is a device for controlling the longitudinal shrinkage in the range of 5-80%. Preferably, the fifth device is a device for controlling the longitudinal shrinkage in the range of 15-65%. Preferably, the fifth device is a device for controlling the longitudinal shrinkage in the range of 59-75%.

[0135] The manufacturing equipment according to the present application has an original technical solution, but each part thereof can be obtained in the prior art, and the third device, the fourth device, the fifth device, the sixth device, the seventh device, the eighth device, and the ninth device can all be selected from components in the prior art.

[0136] By the manufacturing equipment according to the utility model, a multilayer film which is difficult to manufacture qualified products by prior art can be manufactured, the outer layer has a first interface, and the inner layer has a second interface; the first interface and the second interface are embedded with each other; the outer layer and the inner layer are automatically and directly integrated into one in a co-extrusion process, and no longer need the adhesive layer in the prior art; after the co-extrusion process, a substantially circular hole is unexpectedly formed by a dry stretching process, and is no longer the slit-shaped hole in the prior art. The ratio of the total area of the holes in the layer to the surface area of the film is 20-80%, and the hole diameter of the hole is increased by more than 10 times than the prior art.

[0137] In particular, the outermost surface of the porous membrane has a "mouth-shaped" and "back-shaped" rib / groove at the adjacent edge; or, the porous membrane has at least two outer layers and at least one inner layer; the outer layer has a first interface facing the inner layer, and the inner layer has a second interface facing the outer layer; the first interface and the second interface are embedded with each other; the outer layer and the inner layer are automatically and directly integrated into one in a co-extrusion process; the outer layer and the inner layer have circular micropores formed by a dry stretching process.

[0138] According to the above disclosure, those skilled in the art can fully implement the utility model, and further details can be found in prior art documents, textbooks, reference books, industry standards, which need not be repeated here.

[0139] According to the utility model, the microporous membrane is made of an improved dry stretching process (longitudinal and transverse orientation process) and has substantially circular holes and a ratio of longitudinal tensile strength to transverse tensile strength ranging from 0.5 to 6.0, preferably from 0.5 to 5.0, and most preferably from 0.5 to 4.0. The porous membrane, such as the microporous membrane, is a thin, flexible polymeric sheet, foil or film with a plurality of holes extending therethrough. Such a membrane can be a single or multilayer sheet, single or multilayer, composite material, laminate or the like, and can be used in a wide range of applications, including but not limited to mass transfer membranes, pressure regulators, filtration membranes, medical devices, separators for electrochemical storage devices, membranes for fuel cells, and / or similar applications.

[0140] The porous membrane of the utility model is made of an improved dry stretching process (also known as CELGARD process). The dry stretching process refers to a process in which hole formation is caused by stretching a non-porous precursor. See R. Kesting, Synthetic Polymeric Membranes, A structural perspective, Second Edition, John Wiley & Sons, New York, NY, (1985), pages 290-297, incorporated herein by reference. As discussed above, the dry stretching process is distinguished from wet processes and particle stretching processes.

[0141] The present application is distinguished from prior dry-stretch films in at least two ways: 1) substantially circular holes, and 2) a ratio of machine direction tensile strength to transverse direction tensile strength ranging from 0.5 to 6.0, preferably 0.5 to 5.0, most preferably 0.5 to 4.0.

[0142] The present application is distinguished from prior dry-stretch films in at least five ways: 1) substantially circular holes, 2) a ratio of machine direction tensile strength to transverse direction tensile strength ranging from 0.5 to 6.0, 3) an average flow pore size ranging from 0.025 to 0.150 μm, 4) high gas or moisture vapor permeability, JIS Gurley ranging from 0.5 to 200 seconds, and (5) a hydrohead pressure greater than 140 psi.

[0143] With respect to hole shape, the holes are preferably characterized by being substantially circular. See, for example Figure 7A , 7B, 8, 13-16, 19, 20, 22, 23, 28-31, 32, 33, 35, 36, 41-44, 47-50, and 51-54. This hole shape is in contrast to the slit-shaped holes of prior conventional dry-stretch films. See Figure 5A , 5B , 5C, and the Kesting described above. Further, the hole shape of the present application films can be characterized by an aspect ratio, i.e., the ratio of the hole length (MD) to width (TD). In one embodiment of the present application films, the aspect ratio ranges from 0.75 to 1.25. This is in contrast to the aspect ratio of prior dry-stretch films, which is greater than 5.0. See Table I below.

[0144] With respect to the ratio of machine direction (MD) tensile strength to transverse direction (TD) tensile strength, in one embodiment, the ratio is between 0.5 and 6.0, preferably between 0.5 and 5.0. This ratio is in contrast to the corresponding ratio of prior art films, which is greater than 10.0. See Table I below.

[0145] U.S. Patent No. 6,602,593 is directed to microporous films made by a dry-stretch process, wherein the resulting films have a ratio of transverse direction tensile strength to machine direction tensile strength of 0.12 to 1.2. In there, the TD / MD tensile ratio is obtained by a blow-up ratio of at least 1.5 as the precursor is extruded.

[0146] The present application is further characterized in one step by: an average pore size ranging from 0.03 to 0.30 micrometers (μm); a porosity ranging from 20-80%; and / or a transverse direction tensile strength greater than 250 Kg / cm. The foregoing values are exemplary values and are not intended to be limiting, and thus should be considered as representative of only at least selected embodiments of the present application films.

[0147] The present utility model further characterizes: pore size ranging from 0.30 to 1.0 microns (pm); and average aspect ratio ranging from about 1.0 to 1.10. The foregoing values are exemplary values and are not intended to be limiting, and thus should be considered as representative of only at least selected embodiments of the utility model film.

[0148] The present utility model further characterizes: average Aquapore pore size ranging from 0.05 to 0.50 microns (pm); porosity ranging from 40-90%; and / or transverse tensile strength greater than 250 Kg / cm 2 The foregoing values are exemplary values and are not intended to be limiting, and thus should be considered as representative of only at least selected possible preferred embodiments of the utility model film.

[0149] The polymers used in the present utility model can be characterized as thermoplastic polymers. These polymers can further be characterized as semi-crystalline polymers. In one embodiment, the semi-crystalline polymers can be polymers having a crystallinity ranging from 20% to 80%. Such polymers can be selected from the group consisting of polyolefins, fluorocarbons, polyamides, polyesters, polyacetals (or polyformals), polysulfides, polyvinyl alcohols, copolymers thereof, and combinations thereof. Polyolefins can be preferred and can include polyethylenes (LDPE, LLDPE, HDPE, UHMWPE), polypropylenes, polybutylenes, polymethylpentenes, copolymers thereof, and mixtures thereof. Fluorocarbons can include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), fluorinated ethylene propylene (FEP), ethylene chlorotrifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy (PFA) resins, copolymers thereof, and mixtures thereof. Polyamides can include, but are not limited to, polyamide 6, polyamide 6 / 6, nylon 10 / 10, polyphthalamide (PPA), copolymers thereof, and mixtures thereof. Polyesters can include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly-l,4-cyclohexylenedimethylene terephthalate (PCT), and liquid crystal polymers (LCP). Polysulfides include, but are not limited to, polyphenylene sulfide, copolymers thereof, and mixtures thereof. Polyvinyl alcohols include, but are not limited to, ethylene-vinyl alcohol, copolymers thereof, and mixtures thereof.

[0150] The present utility model can include other ingredients as are widely known. For example, those ingredients can include: fillers (inert particulates, often used to reduce film cost, but otherwise do not significantly affect film manufacture), antistatic agents, antiblocking agents, antioxidants, lubricants (to facilitate manufacture), colorants, and / or the like.

[0151] A variety of materials can be added to the polymer to alter or enhance the properties of the film. Such materials include, but are not limited to: (1) polyolefins or polyolefin oligomers having a melting temperature less than 130°C; (2) mineral fillers including, but not limited to: calcium carbonate, zinc oxide, diatomaceous earth, talc, kaolin, synthetic silica, mica, clay, boron nitride, silica dioxide, titanium dioxide, barium sulfate, aluminum hydroxide, magnesium hydroxide, and / or the like, and mixtures thereof; (3) elastomers including, but not limited to: ethylene propylene (EPR), ethylene propylene diene (EPDM), styrene butadiene (SBR), styrene isoprene (SIR), ethylidene norbornene (ENB), epoxy resins, and polyurethanes, and mixtures thereof; (4) wetting agents including, but not limited to, ethoxylated alcohols, primary polymeric carboxylic acids, glycols (e.g., polypropylene glycol and polyethylene glycol), functionalized polyolefins, and the like; (5) lubricants such as, for example, siloxanes, fluoropolymers, oleamide, stearamide, erucamide, calcium stearate, or other metal stearates; (6) flame retardants such as, for example, brominated flame retardants, ammonium phosphate, ammonium hydroxide, aluminum trihydrate, and phosphate esters; (7) crosslinking or coupling agents; (8) polymer processing aids such as, but not limited to, plasticizers or processing oils, e.g., less than 10% by weight of processing oil; and (9) any type of nucleating agent including beta-nucleating agents for polypropylene. (However, the present invention specifically excludes any beta-nucleated polypropylene (BNPP) such as disclosed in U.S. Patent No. 6,368,742, incorporated herein by reference. A beta-nucleating agent for polypropylene is a substance that induces the formation of beta crystals in polypropylene).

[0152] The present invention can be a monolayer film or a multilayer film. With respect to a multilayer film, the machine direction and transverse direction oriented film of the present invention can be one ply or layer of the multilayer film or the film of the present invention can be all of the plies or layers of the multilayer film. If the film of the present invention is less than all of the plies or layers of the multilayer film, the multilayer film can be made by a coating, lamination, or bonding process. If the film of the present invention is all of the plies or layers of the multilayer film, the multilayer film can be made by a lamination or extrusion process such as co-extrusion. Further, the multilayer film can be made from plies or layers of the same material or different materials.

[0153] The film of the present invention is preferably made by a modified dry-stretch process in which the precursor film is stretched in both the machine direction and the transverse direction (i.e., not only in the machine direction but also in the transverse direction). This process will be discussed in more detail below.

[0154] Generally, the process to make the aforementioned films includes the steps of extruding a non-porous (mono- or multi-layer) precursor, and subsequently stretching the non-porous precursor in the machine direction and the cross direction. Optionally, the non-porous precursor can be annealed prior to stretching. In one embodiment, the stretching includes machine direction stretching and cross direction stretching with simultaneous controlled machine direction relaxation. The machine direction stretching and the cross direction stretching can be simultaneous or sequential. In one embodiment, the machine direction stretching is followed by cross direction stretching with simultaneous machine direction relaxation. The process will be discussed in more detail below.

[0155] Extrusion is generally conventional (conventional in the sense that it is conventional for dry-stretch processes). The extruder can have a slot die (for flat precursors) or a ring die (for bead or bubble precursors). In the latter case, a blown bubble technique can be used [e.g., a blow up ratio (BUR) of less than 1.5 when the precursor is extruded]. However, the birefringence of the non-porous precursor need not be as high as in conventional dry-stretch processes. For example, in a conventional dry-stretch process to produce a film having > 35% porosity from a polypropylene resin having a melt flow index (MFI) < 1.0, the birefringence of the precursor would be > 0.0130; however, with the present process, the birefringence of the PP precursor would be as low as 0.0100. In another example, a film from a polyethylene resin having > 35% porosity, the birefringence of the precursor would be > 0.0280; however, with the present process, the PE precursor birefringence would be as low as 0.0240.

[0156] In one embodiment, the annealing (optional) can be performed at a temperature between T m - 80°C and T m - 10°C (where T m is the melting temperature of the polymer); and in another embodiment, at a temperature between T m - 50°C and T m - 15°C. Some materials, for example, those having a high degree of crystallinity after extrusion, such as polybutylene, can not require annealing. Additional optional steps, such as, but not limited to, heat setting, extraction, removal, winding, slitting, and / or the like, can be performed.

[0157] The machine direction stretching can be performed as cold stretching or hot stretching or both, and as a single step or multiple steps. In one embodiment, the cold stretching can be performed at < T m - 50°C, and in another embodiment, at < T m - 80°C. In one embodiment, the hot stretching can be performed at < T m - 10°C. In one embodiment, the total machine direction stretching can be in the range of 50-500%, and in another embodiment, in the range of 100-300%. During the machine direction stretching, the precursor can contract in the cross direction (conventionally).

[0158] The transverse stretching includes a simultaneous controlled longitudinal relaxation. This means that as the precursor is stretched in the transverse direction (TD stretching), the precursor is simultaneously allowed to shrink (i.e., relax) in the machine direction (MD relaxation) in a controlled manner. The transverse stretching can be performed as a cold step or a hot step, or a combination of both. In one embodiment, the total transverse stretching can be in the range of 100-1200%, and in another embodiment, in the range of 200-900%. 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 transverse stretching can be performed in multiple steps. During the transverse stretching, the precursor can or can not be allowed to shrink in the machine direction. In embodiments of multiple step transverse stretching, the first transverse step can include a transverse stretching with a controlled longitudinal relaxation, followed by a simultaneous transverse and longitudinal stretching, and followed by a transverse relaxation and no longitudinal stretching or relaxation.

[0159] Optionally, the precursor after the longitudinal and transverse stretching can be heat set, as is widely known.

[0160] The foregoing film and process embodiments are further illustrated in the following non-limiting examples.

[0161] Examples

[0162] Unless otherwise indicated, the test values reported herein were measured as follows: thickness - ASTM-D374 using Emveco Microgage 210-A micrometer; porosity - ASTM D-2873; tensile strength - ASTM D-882 using an Instron Model 4201; and aspect ratio - measurements from SEM micrographs.

[0163] The following examples were produced by conventional dry stretching techniques, except as noted.

[0164] Example 1:

[0165] A polypropylene (PP) resin was extruded using a 2.5 inch extruder. The extruder melt temperature was 221 °C. The molten polymer was fed into a circular die. The die temperature was set at 220 °C and the molten polymer was cooled by blowing air. The extruded precursor had a thickness of 27 microns (μm) and a birefringence of 0.0120. The extruded film was then annealed at 150 °C for 2 minutes. The annealed film was then cold stretched at room temperature to 20% and then hot stretched at 140 °C to 228% and relaxed to 32%. The machine direction (MD) stretched film had a thickness of 16.4 μm and a porosity of 25%. The MD stretched film was then stretched in the transverse direction (TD) at 140 °C by 300% and the MD was relaxed by 50%. The finished film had a thickness of 14.1 μm and a porosity of 37%. The TD tensile strength of the finished film was 550 Kg / cm 2 . See Figure 7A .

[0166] Example 2:

[0167] A polypropylene (PP) resin was extruded using a 2.5 inch extruder. The extruder melt temperature was 220 °C. The molten polymer was fed into a circular die. The die temperature was set at 200 °C and the molten polymer was cooled by blowing air. The extruded precursor had a thickness of 9.5 microns (μm) and a birefringence of 0.0160. A HDPE resin was extruded using a 2.5 inch extruder. The extruder melt temperature was 210 °C. The molten polymer was fed into a circular die. The die temperature was set at 205 °C and the molten polymer was cooled by air. The extruded precursor had a thickness of 9.5 μm and a birefringence of 0.0330. The two PP layers and one PE layer were laminated together to form a PP / PE / PP three layer film. The lamination roll temperature was 150 °C. The laminated three layer film was then annealed at 125 °C for 2 minutes. The annealed film was then cold stretched at room temperature to 20% and then hot stretched at 113 °C to 160% and relaxed to 35%. The MD stretched film had a thickness of 25.4 μm and a porosity of 39%. The MD stretched film was then stretched in the TD at 115 °C by 400% and the MD was relaxed by 30%. The finished film had a thickness of 19.4 μm and a porosity of 63%. The TD tensile strength of the finished film was 350 Kg / cm 2 . See Figure 7B .

[0168] Example 3:

[0169] A PP resin and a HDPE resin were coextruded using a coextrusion die to form a PP / PE / PP three layer film. The extruder melt temperature for the PP was 243°C and the extruder melt temperature for the PE was 214°C. The melted polymers were then fed into a coextrusion die set at 198°C. The melted polymers were cooled by blowing air. The extruded film had a thickness of 35.6 μm. The extruded precursor was then annealed at 125°C for 2 minutes. The annealed film was then cold stretched in the MD to 45% and hot stretched in the TD to 247% and relaxed to 42% at 113°C. The MD stretched film had a thickness of 21.5 μm and a porosity of 29%. The MD stretched film was then TD stretched 450% at 115°C, MD relaxed 50%. The finished film had a thickness of 16.3 μm and a porosity of 59%. The TD tensile strength of the finished film was 570 Kg / cm 2 .

[0170] Example 4:

[0171] A PP resin and a HDPE resin were coextruded using the same system as Example 3 and MD stretched. The MD stretched film was then TD stretched 800% at 115°C, MD relaxed 65%. The finished film had a thickness of 17.2 μm and a porosity of 49%. The TD tensile strength of the finished film was 730 Kg / cm 2 . See Figure 8 .

[0172] Example 5:

[0173] A PP resin and a PB resin were coextruded using a coextrusion die. The extruder melt temperature for the PP was 230°C and the extruder melt temperature for the PB was 206°C. The melted polymers were then fed into a coextrusion die set at 210°C. The melted polymers were then cooled by blowing air. The extruded film had a thickness of 36.0 μm. The extruded precursor was then annealed at 105°C for 2 minutes. The annealed film was then cold stretched to 20% and then hot stretched to 155% at 105°C and then relaxed to 35%. The MD stretched film was then TD stretched 140% at 110°C, MD relaxed 20%. The finished film had a thickness of 14.8 μm and a porosity of 42%. The TD tensile strength of the finished film was 286 Kg / cm 2 .

[0174] Example 6:

[0175] A PP resin and a PE resin were extruded using a coextrusion die to form a PP / PE / PP three layer film. The extruder melt temperature for the PP was 245°C and the extruder melt temperature for the PE was 230°C. The molten polymers were then fed into a coextrusion die set at 225°C. The molten polymers were cooled by blowing air. The extruded film had a thickness of 27 μm and a birefringence of 0.0120. The extruded precursor was then annealed at 115°C for 2 minutes. The annealed film was then cold stretched at room temperature to 22% and hot stretched at 120°C to 254% and relaxed to 25% (total machine direction stretch = 251%). The MD stretched film had a thickness of 15 μm and a porosity of 16%. The MD stretched film was then TD stretched at 130°C by 260%, MD relaxed by 50%, then simultaneously MD and TD stretched at 130°C by 50% and 216% in each direction, and the final film was firmly held on the MD (100%) and allowed to relax on the TD by 57.6% at a temperature of 130°C. The finished film had a thickness of 7.6 μm and a porosity of 52%. The TD tensile strength of the finished film was 513 Kg / cm and the birefringence.

[0176] Example 7:

[0177] A polypropylene and a polyethylene resin(s) were extruded using a coextrusion die to form a PP / PE / PP three layer film. The extruder melt temperature for the PP was 222°C and the extruder melt temperature for the PE was 225°C. The molten polymers were then fed into a coextrusion die set at 215°C. The molten polymers were cooled by blowing air. The extruded film had a thickness of 40 μm and a birefringence of 0.0110. The extruded precursor was then annealed at 105°C for 2 minutes. The annealed film was then cold stretched at room temperature to 36% and hot stretched at 109°C to 264% and relaxed to 29% (total machine direction stretch = 271%). The MD stretched film had a thickness of 23.8 μm and a porosity of 29.6%. The MD stretched film was then TD stretched at 110°C by 1034%, MD relaxed by 75%. The finished film had a thickness of 16.8 μm and a porosity of 46%. The TD tensile strength of the finished film was 1037 Kg / cm and the birefringence. 2 .

[0178] In the following Table I, the results of the foregoing examples are summarized and compared to two commercially available dry stretched films: Comparative Example A) 2400 (single layer sheet polypropylene film), see Figure 5B ; and Comparative Example B) 2300 (three layer polypropylene / polyethylene / polypropylene), see Figure 5C .

[0179] Table I

[0180]

[0181] According to the present application, for single layer PP air filtration membranes, the preferred JIS Gurley is <2.5 to 25; for single layer PP HEPA / ULPA membranes, the preferred JIS Gurley is <0.5 to 5; preferred round hole structure and uniform height of holes through the membrane.

[0182] According to at least the selected possible preferred embodiments of the present application, the preferred membranes are or have: made from dry process, no oil / solvent added; high porosity: 40-90%; highly hydrophobic; water head pressure > 140 psi; water intrusion pressure > 80 psi.

[0183] Unique pore structure characterized by capillary flow pore size / Aquapore testing / SEM: average flow pore size measured by capillary flow of at least about 0.04 microns; uniform, round or non-slit type of pore structure with a narrow range of pore diameters. Aquapore pore size is at least about 0.07 microns.

[0184] High gas / air / water vapor permeability: JIS Gurley is 1.0 to 100; high flow rate characterized by capillary flow air porosity; WVTR > 8,000 g / m 2 - day; balanced MD / TD strength: TD strength (> 300 kg / cm 2 ); low TD shrinkage: TD shrinkage < 2% at 90°C; preferred PP polymer: MFI = 0.1 to 10.0, polymer crystallinity > 45%; preferred PE polymer: MFI = 0.01 to 5.0, crystallinity > 50%.

[0185] MFI tested with ASTM D-1238 system.

[0186] Below are the test results for eight membranes (A-G and M), composite materials or laminates according to the selected embodiments of the present application and the test results for comparative sample Com C:

[0187] Table II: Overall Performance

[0188]

[0189] WVTR testing is based on ASTM F2298-03, utilizing a water vapor gradient system.

[0190] Test system utilizing a dynamic moisture permeation chamber for cloth water vapor diffusion resistance and air flow resistance.

[0191] Test Conditions: Top chamber humidity 95%, bottom chamber humidity 5%, water vapor gradient 90%. Ambient temperature.

[0192] Thickness is measured based on ASTM-D374 using an Emveco Microgage 210A micrometer. JIS Gurley is a gas permeability test measured using an OHKEN permeability tester. JIS Gurley is defined as the time in seconds required for 100 cc of air to pass through 1 square inch of film under a constant pressure of 4.8 inches of water.

[0193] Porosity is measured by the system ASTM D2873.

[0194] Breakdown strength is measured using an Instron Model 4442 based on ASTM D3763. The measurement is made across the width of the film and the average breakdown energy (breakdown strength) is defined as the force required to break the test sample.

[0195] Tensile properties are tested using the ASTM-882 standard using an Instron Model 4201.

[0196] Shrinkage is measured using a modified ASTM-2732-96 procedure at 90°C for 60 minutes.

[0197] Average flow pore size, bubble point pore diameter is measured based on the ASTM F316-86 standard capillary flow analysis.

[0198] Hydrohead pressure is measured based on ASTM D3393-91.

[0199] Water intrusion is tested by ASTM F316-93 (wetting fluid - water, 68.8 dynes / cm. Gas: air).

[0200] Although not preferred, filled microporous ultra-high molecular weight polyethylene films can be used as precursors in the stretching process to achieve the present application.

[0201] In the meantime, the films of the present application can be laminated to a nonwoven substrate on one or both sides to achieve additional durability, or can be coated with a surfactant to make them hydrophilic.

[0202] According to at least selected embodiments, the present application can involve:

[0203] Stretching and relaxing simultaneously, a stretch-blow film is produced useful in applications requiring high levels of permeability to air, moisture and other gases, but also high levels of hydrophobicity. Such applications can include membrane-based humidity and temperature control systems, such as liquid desiccant HVAC systems; membrane desalination; ventilation; fuel cell water vapor control; liquid filtration; and similar applications.

[0204] Table III: Properties of Films

[0205] Measurement Units Performance Thickness μm 10-100 JIS Gurley sec / 100ml 1-100 MD Tensile Strength kgf / cm 2 ]]> 500-1500 TD Tensile Strength kgf / cm 2 ]]> 350-800 Porosity ％ 60-90％ Average Flow Pore Diameter μm 0.04-0.07 Bubble Point Diameter μm 0.09-0.11 Aquapore Size μm 0.04-0.12 Water Head Pressure psi 149-222 Invasion Pressure Psi >80 Pressure Drop psid at 5.3 cm / sec) <3.90 Particle Efficiency % (at 2.5 cm / sec) >99.99％ Melting Point ℃ >165

[0206] According to a preferred embodiment of the present application, the film is a hydrophobic, highly permeable, chemically and mechanically stable high tensile strength film. These properties appear to make it an ideal membrane for the following applications, each of which (except for air filtration) can involve selective passage of moisture and blocking of liquid water: 1. HVAC; 2. Liquid-Desiccant (LD) air conditioning; 3. Water-based air conditioning; 4. Energy Recovery Ventilation (ERV); 5. Desalination; 6. RO desalination; 7. Vapor desalination; 8. Fuel cells; 9. Liquid and / or air filtration.

[0207] In particular in the case of liquid and air filtration, the unique pore structure can have some particular benefits.

[0208] According to a preferred laminate product of the present application can have a combination of desirable film water vapor transport properties combined with desirable macroscopic physical properties.

[0209] According to at least selected embodiments, a preferred single layer PP product can have an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport (moisture transport) and hydrohead properties. The film can also have an atypically high porosity (> 60%), but still maintain balanced physical properties when compared to more conventional films. At the same time, the film can be produced in-line with a laminated PP nonwoven. The resulting laminate product can still maintain excellent moisture transport and even more improved hydrohead properties. At the same time, the resulting product can have physical strength properties that far exceed comparative films. Thus, the product can have the added advantage of being useful in more physically adverse environments without losing the highly desirable film characteristics.

[0210] According to at least selected embodiments of the present application, the film can have a unique pore structure and distribution or properties that can appear to make it an ideal membrane for the following applications: high efficiency air filtration, HEPA / ULPA applications, near zero emission dust removal applications (clean rooms, vacuum bags, face masks, surgical departments, dust containment bags, boxes); filtration applications: high efficiency HVAC filter media, HEPA / ULPA media, filtration membrane composites; liquid filtration, protective clothing, functional clothing / performance sportswear, medical fabrics, and the like.

[0211] According to the present application, some improved aspects can include pore shapes that are not slits, round holes, increased cross-directional tensile strength, balance of MD and TD physical properties, high performance related to, for example, water vapor transport (or moisture transport) and hydrohead pressure, reduced Gurley, high porosity with balanced physical properties, uniformity of pore structure including pore size and pore size distribution, increased durability, composites of such films and other porous materials, composites or laminates of such films, membranes or layers with porous nonwovens, coated films, co-extruded films, laminated films, films with desired water vapor transport, hydrohead performance and physical strength properties, usefulness in more physically adverse environments without loss of desired film characteristics, combinations of film water vapor transport (or moisture transport) performance coupled with macroscopic physical properties, being hydrophobic, highly permeable, chemically and mechanically stable, having high tensile strength, combinations thereof, and / or the like.

[0212] While some films made by dry-stretching processes have met with excellent commercial success, there is a need to improve, modify or enhance at least selected physical attributes thereof so that they can be used in a wider range of applications, perform better for specific purposes, and the like. According to the present application, some improved aspects can include pore shapes that are not slits, round holes, increased cross-directional tensile strength, balance of MD and TD physical properties, uniformity of pore structure including pore size and pore size distribution, high performance related to, for example, water vapor transport (or moisture transport) and hydrohead pressure, reduced Gurley, high porosity with balanced physical properties, increased durability, composites of such films and other porous materials, composites or laminates of such films with porous nonwovens, coated films, co-extruded films, laminated films, films with desired water vapor transport (or moisture transport), hydrohead performance and physical strength properties, usefulness in more physically adverse environments without loss of desired film characteristics, combinations of film water vapor transport (or moisture transport) performance coupled with macroscopic physical properties, combinations thereof, and / or the like.

[0213] According to at least selected potentially preferred embodiments, the porous film of the present application can preferably be a dry-stretched process porous film, membrane, layer or composite that is hydrophobic, highly permeable, chemically and mechanically stable, has high tensile strength, and combinations thereof. These properties appear to make it an ideal film or membrane for use in applications where each application (air filtration excepted) can involve selective passage of moisture (or other gas) and blocking of liquid water (or other liquid):

[0214] 1. HVAC:

[0215] a) Liquid-desiccant (LD) air conditioning (temperature and humidity control): In a membrane-based LD system, temperature and humidity can be controlled by a salt solution that absorbs or gives off water vapor through a porous membrane. Heat is the driving force in the system (not pressure as in most air conditioning systems). To make the system work, it can be necessary to have a hydrophobic membrane that is easily permeable to water vapor (to prevent liquid).

[0216] b) Water-based air conditioning (temperature and humidity control): Steam cooling systems or chilled water systems operate on somewhat different principles than LD systems, but will use the same basic properties of the membrane.

[0217] c) Energy recovery ventilation system (ERV): The simplest HVAC application uses a membrane as the key component for heat and humidity exchange between make-up and exhaust air.

[0218] 2. Desalination: Steam desalination applications use the same membrane properties as HVAC. Because the membrane resists liquid brine but passes water vapor, a system can be constructed that separates brine and fresh water across the membrane. For higher temperature brine, fresh water vapor is released from the brine, migrates through the membrane, and is concentrated to form a fresh water stream.

[0219] 3. Fuel cells: In fuel cells, the proton exchange membrane (PEM) must be kept continuously wet. This can be accomplished by using a membrane-based humidification unit.

[0220] 4. Liquid and / or air filtration: In these embodiments, the porous membrane can act as a simple filter. When liquid, vapor, gas, or air passes through the membrane, particles that are too large to pass through the pores are blocked on the membrane surface.

[0221] In particular in the case of liquid and air filtration, the unique pore structure of at least the selected embodiments of the present application can have some particular benefits, such as durability, high efficiency, narrow pore size distribution, and uniform flow rate benefits.

[0222] According to at least one selected porous material or porous film embodiment of the present application, at least one selected porous monolayer polypropylene (monolayer PP) film has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected monolayer PP film can also have a high porosity (> 60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected monolayer PP film or film can be produced integrally with or laminated to a porous polypropylene (PP) nonwoven material (nonwoven PP) on one or both sides thereof. The resulting composite, film or product (monolayer PP / nonwoven PP) or (nonwoven PP / monolayer PP / nonwoven PP) can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product (monolayer PP / nonwoven PP) or (nonwoven PP / monolayer PP / nonwoven PP) can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product (monolayer PP / nonwoven PP) or (nonwoven PP / monolayer PP / nonwoven PP) can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected monolayer PP films and composite products (monolayer PP; monolayer PP / nonwoven PP; or, nonwoven PP / monolayer PP / nonwoven PP) are unique in the combination of their macroscopic physical properties combined with their film water vapor transport performance. For example, existing films can have porosity, but not sufficient hydrohead pressure or performance, other films are too fragile, other films are robust but lack other properties, etc. Yet the at least one selected embodiment of the present application can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0223] According to the present application, at least one selected porous multi-layer polypropylene (multi-layer PP) film has excellent MD and TD physical property balance, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected multi-layer PP film can also have high porosity (> 60%), but still maintain balanced physical properties when compared to more conventional films. At the same time, the selected multi-layer PP film or film can be integrally produced with or laminated to a porous polypropylene (PP) nonwoven material (nonwoven PP) on one or both sides thereof. The resulting composite, film or product (multi-layer PP / nonwoven PP) or (nonwoven PP / multi-layer PP / nonwoven PP) can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product (multi-layer PP / nonwoven PP) or (nonwoven PP / multi-layer PP / nonwoven PP) can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product (multi-layer PP / nonwoven PP) or (nonwoven PP / multi-layer PP / nonwoven PP) can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected multi-layer PP films and composite products (multi-layer PP; multi-layer PP / nonwoven PP; or, nonwoven PP / multi-layer PP / nonwoven PP) are unique in the combination of their macroscopic physical properties combined with their film water vapor transport performance. For example, existing films can have porosity, but not sufficient hydrohead pressure or performance, other films are too brittle, other films are strong but lack other properties, etc. Whereas the present application at least selected embodiments can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0224] According to the present application, at least one selected porous monolayer polyethylene (monolayer PE) film has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected monolayer PE film can also have a high porosity (> 60%), but still maintain balanced physical properties when compared to more conventional films. At the same time, the selected monolayer PE film or film can be integrally produced with or laminated to a porous polyethylene (PE) nonwoven (nonwoven PE) or a porous polypropylene (PP) nonwoven (nonwoven PP) on one or both sides thereof. The resulting composite, film or product (monolayer PE / nonwoven PE) or (nonwoven PE / monolayer PE / nonwoven PE) can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product (monolayer PE / nonwoven PE) or (nonwoven PE / monolayer PE / nonwoven PE) can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product (monolayer PE / nonwoven PE) or (nonwoven PE / monolayer PE / nonwoven PE) can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected monolayer PE films and composite products (monolayer PE; monolayer PE / nonwoven PE; or, nonwoven PE / monolayer PE / nonwoven PE) are unique in the combination of their macroscopic physical properties combined with their film water vapor transport performance. For example, existing films can have porosity, but not sufficient hydrohead pressure or performance, other films are too brittle, other films are strong but lack other properties, etc. Whereas the present application at least selected embodiments can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0225] According to the present application, at least one selected porous multi-layer polyethylene (multi-layer PE) film has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport and hydrohead performance. The selected multi-layer PE film can also have a high porosity (> 60%), but still maintain balanced physical properties when compared to more conventional films. At the same time, the selected multi-layer PE film or film can be integrally produced with or laminated to a porous polyethylene (PE) nonwoven (nonwoven PE) or a porous polypropylene (PP) nonwoven (nonwoven PP) on one or both sides thereof. The resulting composite, film or product (multi-layer PE / nonwoven PE) or (nonwoven PE / multi-layer PE / nonwoven PE) can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product (multi-layer PE / nonwoven PE) or (nonwoven PE / multi-layer PE / nonwoven PE) can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product (multi-layer PE / nonwoven PE) or (nonwoven PE / multi-layer PE / nonwoven PE) can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected multi-layer PE films and composite products (multi-layer PE; multi-layer PE / nonwoven PE; or, nonwoven PE / multi-layer PE / nonwoven PE) are unique in the combination of their macro physical properties combined with their film water vapor transport performance. For example, existing films can have porosity, but not enough hydrohead pressure or performance, other films are too brittle, other films are strong but lack other properties, etc. Whereas the present application at least selected embodiments can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0226] According to the present application, at least one selected porous monolayer polymeric film, for example, a monolayer (may have one or more plies) polyolefin (PO) film, such as a polypropylene (PP) and / or polyethylene (PE) (including PE, PP, or PE+PP blend) monolayer film, has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport (or moisture vapor transport) and hydrohead performance. The selected monolayer PO film can also have a high porosity (>60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected monolayer PO film or film can be integrally produced with or laminated to a porous nonwoven material on one or both sides, such as a nonwoven polymeric material, for example, a PO nonwoven material [such as a porous polyethylene (PE) nonwoven material (nonwoven PE) and / or a porous polypropylene (PP) nonwoven material (nonwoven PP) (including PE, PP, or PE+PP blend)]. The resulting composite, film, or product (monolayer PO / nonwoven PO) or (nonwoven PO / monolayer PO / nonwoven PO) can preferably maintain excellent water vapor transport (or moisture vapor transport) and even more improved hydrohead performance. At the same time, the resulting composite product (monolayer PO / nonwoven PO) or (nonwoven PO / monolayer PO / nonwoven PO) can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product (monolayer PO / nonwoven PO) or (nonwoven PO / monolayer PO / nonwoven PO) can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected monolayer PO films and composite products (monolayer PO; monolayer PO / nonwoven PO; or, nonwoven PO / monolayer PO / nonwoven PO) are unique in the combination of their macro physical properties combined with their film water vapor transport performance. The present application at least selected embodiments can have, for example, desirable porosity, water vapor transport, moisture vapor transport, hydrohead pressure, strength, etc.

[0227] According to the present utility model, at least one selected porous multi-layer polymeric film, for example, a multi-layer (two or more layers) polyolefin (PO) film, such as a polypropylene (PP) and / or polyethylene (PE) (including PE, PP or PE+PP blend) multi-layer film, has an excellent balance of MD and TD physical properties, while also being a high performance film, as measured by water vapor transport (or moisture vapor transport) and hydrohead performance. The selected multi-layer PO film can also have a high porosity (> 60%), but still maintain a balanced physical property when compared to more conventional films. At the same time, the selected multi-layer PO film or film can be integrally produced with or laminated to a porous PO nonwoven material on one or both sides thereof [such as a porous polyethylene (PE) nonwoven material (nonwoven PE) and / or a porous polypropylene (PP) nonwoven material (nonwoven PP)] on one or both sides thereof. The resulting composite, film or product (multi-layer PO / nonwoven PO) or (nonwoven PO / multi-layer PO / nonwoven PO) can preferably maintain excellent water vapor transport and even more improved hydrohead performance. At the same time, the resulting composite product (multi-layer PO / nonwoven PO) or (nonwoven PO / multi-layer PO / nonwoven PO) can have physical strength properties far exceeding comparative films. Thus, the new resulting composite product (multi-layer PO / nonwoven PO) or (nonwoven PO / multi-layer PO / nonwoven PO) can have the added advantage of being useful in more physically adverse environments without losing highly desirable film characteristics. It is believed that these selected multi-layer PO films and composite products (multi-layer PO; multi-layer PO / nonwoven PO; or, nonwoven PO / multi-layer PO / nonwoven PO) are unique in the combination of their macroscopic physical properties combined with their film water vapor transport performance. For example, existing films can already have porosity, but not enough hydrohead pressure or performance, other films are too fragile, other films are robust but lack other properties, etc., while at least selected embodiments of the present utility model can have, for example, desired porosity, water vapor transport, hydrohead pressure, strength, etc.

[0228] According to the present utility model, the pores (openings) have the following pore aspect ratio [based on the physical dimensions of the pore openings in the machine direction (MD) (length) and the transverse direction (TD) (width)], by measuring one or more pores (preferably some pores to determine an average) in a SEM of the surface, top or front face (A side) of, for example, a selected film or composite, such as a single, double or triple layer film: a typical range of MD / TD aspect ratio of 0.75 to 1.50; a preferred range of MD / TD aspect ratio of 0.75 to 1.25; a more preferred range of MD / TD aspect ratio of 0.85 to 1.25.

[0229] According to the at least selected porous material or porous membrane embodiments of the present inventive subject matter, the three-dimensional or 3D MD / TD / ND pore sphericity coefficient or ratio range can be: 0.25 to 8.0 or more; can be preferably 0.50 to 4.0; and can be most preferably 1.0 to 2.0 or less.

[0230] According to the at least selected porous material or porous membrane embodiments of the present inventive subject matter, the three-dimensional or 3D MD / TD / ND pore sphericity coefficient or ratio range can be: 0.25 to 8.0 or more; can be preferably 0.50 to 4.0; and can be most preferably 1.0 to 2.0 or less.

[0231] According to the at least selected porous material or porous membrane embodiments of the present inventive subject matter, the pores (openings) have the following pore aspect ratio [based on the physical dimensions of the pore openings in the machine direction (MD) (length) and the transverse direction (TD) (width)] based on measuring the pores in the SEM of the top or front (A-side) of the selected monolayer and trilayer membranes: Here are the typical numbers for the aspect ratio range of the machine direction MD (length) and the transverse direction TD (width): MD / TD aspect ratio range of 0.75 to 1.50.

[0232] According to the at least selected porous material or porous film embodiments of the present inventive subject matter, the pores (openings) have the following three-dimensional or 3D sphericity coefficients or ratios [based on the physical dimensions of the pore openings in the machine direction (MD) (length), transverse direction (TD) (width), and thickness direction or cross-section (ND) (thickness)]: for example, one or more of the pores (preferably some of the pores to determine an average) in a SEM measuring the surface, top or front (A-side), surface, bottom or back (B-side), and cross-section, depth or height (C-side) (length or width cross-section or both) of a selected film, layer or composite material such as a selected monolayer and trilayer film: for example: a MD / TD aspect ratio in the typical range of 0.75 to 1.50, a MD / ND size ratio in the range of 0.50 to 7.50, a TD / ND size ratio in the range of 0.50 to 5.00. A preferred MD / TD aspect ratio in the range of 0.75 to 1.25, a MD / ND size ratio in the range of 1.0 to 2.5, a TD / ND size ratio in the range of 1.0 to 2.5. A more preferred MD / TD aspect ratio in the range of 0.85 to 1.25, a MD / ND size ratio in the range of 1.0 to 2.0, a TD / ND size ratio in the range of 1.0 to 2.0.

[0233] According to the present inventive subject matter, the pores (openings) have the following sphericity coefficients or ratios [based on the physical dimensions of the pore openings in the machine direction (MD) (length), transverse direction (TD) (width), and thickness direction or cross-section (ND) (thickness)] based on measuring the pores in a SEM at the top or front (A-side) and length and cross-section (C-side) of a selected monolayer and trilayer film:

[0234] Here are typical numbers for the sphericity coefficients or ratios ranges for the machine direction MD (length), transverse direction TD (width), and thickness direction ND (vertical height): a MD / TD aspect ratio in the range of 0.75 to 1.50; a MD / ND size ratio in the range of 0.50 to 7.50; a TD / ND size ratio in the range of 0.50 to 5.00.

[0235] According to the present inventive subject matter, the microporous film is made by a dry stretching process and has substantially circular pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 6.0, preferably 0.5 to 5.0. A system for making the aforementioned microporous film includes the steps of: extruding a polymer as a non-porous precursor, and stretching the non-porous precursor in the machine direction and in the transverse direction, the stretching in the transverse direction including simultaneous controlled relaxation in the machine direction.

[0236] According to the present application, porous membranes are made from an improved dry-stretching process and have substantially circular pores, a ratio of longitudinal tensile strength to transverse tensile strength in the range of 0.5 to 6.0, and either a low Gurley compared to prior dry-stretched membranes, a larger and more uniform mean flow pore size compared to prior dry-stretched membranes, or both a low Gurley and a larger and more uniform mean flow pore size compared to prior dry-stretched membranes.

[0237] While membranes made from conventional dry-stretching processes have met with great commercial success, the present application provides improved, modified, or enhanced at least selected physical properties thereof so that they can be used in a wider range of applications, perform better for specific purposes, and the like.

[0238] While at least some air filters have met with commercial success, the present application provides improved, modified, or enhanced filtration media so that they can be used in a wider range of filtration or separation applications, perform better for specific purposes, and the like.

[0239] While some such flat sheet porous materials used in filtration or separation processes have met with commercial success, the present application provides improved, modified, or enhanced porous materials so that they can be used in a wider range of applications, perform better for specific purposes, and the like.

[0240] While porous materials for selectively passing gases or moisture (water vapor) and blocking liquid water or brine can have met with commercial success, such as the RO membranes sold by Dow Chemical, the ePTFE membranes sold by W. L. Gore, BHA, and the like, the present application provides improved, modified, or enhanced porous materials so that they can be used in a wider range of applications, perform better for specific purposes, and the like.

[0241] According to the present application, air filters include at least one porous membrane, such as a microporous membrane.

[0242] According to the present application, microporous membranes are made from a dry-stretching process and have substantially circular pores and a ratio of longitudinal tensile strength to transverse tensile strength in the range of 0.5 to 5.0. A system for making the foregoing microporous membranes includes the steps of extruding a polymer into a non-porous precursor, and stretching the non-porous precursor in the machine direction and in the transverse direction, the stretching in the transverse direction including simultaneous controlled relaxation in the machine direction.

[0243] According to the present application, porous membranes are made from an improved dry-stretching process and have substantially circular pores, a ratio of longitudinal tensile strength to transverse tensile strength in the range of 0.5 to 6.0, and either a low Gurley compared to prior dry-stretched membranes, a larger and more uniform mean flow pore size compared to prior dry-stretched membranes, or both a low Gurley and a larger and more uniform mean flow pore size compared to prior dry-stretched membranes.

[0244] The air filter cartridge according to the present application can include at least one pleated microporous membrane, a plurality of microporous membranes, and it can further include end plates, partitions, or the like.

[0245] As used herein, an air filter cartridge refers to a cartridge that can be used in an air filter or an air purifier. Meanwhile, the membrane can be pleated so as to provide a large filtration area in a relatively small volume. In alternative embodiments, the membrane can have a sinusoidal pattern so as to provide a large filtration area in a relatively small volume.

[0246] Further, the membrane can have any configuration; for example, it can have a configuration selected from a pleated cylindrical configuration, a pleated flat sheet configuration, and a spiral wound configuration.

[0247] In an example manufacturing process, at least one flat sheet microporous membrane is constructed, and then the membrane is folded into a pleated or accordion shape, thereby increasing the filtration area. Then, the pleated membrane can be rolled into a cylinder and sealed with end plates, thereby forming an air filter cartridge. The air filter cartridge can be inserted into a housing and sealed with an end cap.

[0248] According to at least selected embodiments that can be well suited as battery separators, the preferred membrane is preferably made of one or more polyolefins and can further be characterized by one or more of the following parameters: thickness, porosity, average pore size, breakdown strength, JIS Gurley number, and shutdown temperature.

[0249] The membrane thickness can be less than 6.0 mils (150 microns). In another embodiment, the thickness can be in the range of 10 microns to 150 microns. In yet another embodiment, the thickness can be in the range of 10 microns to 50 microns.

[0250] The membrane porosity can be between 40% and 90%. In one embodiment, the porosity is in the range of 60-90%. In yet another embodiment, the porosity is in the range of 65-80%.

[0251] The membrane average Aquapore pore size can be between 0.04-0.20 microns. In one embodiment, the average pore size is in the range of 0.04-0.120 microns. In yet another embodiment, the average pore size is in the range of 0.07-0.12 microns.

[0252] Breakdown strength can be greater than or equal to 300 gr-force / mil. Breakdown strength is determined by averaging 10 measurements across the width of the final product, recording data with a Midtech Stevens LFRA texture analyzer and a 1.65 mm diameter needle and 0.5 mm radius at a speed of 2 mm / sec with a maximum deflection of 6 mm.

[0253] JIS Gurley number (normalized to 1 mil thickness) can be less than 100 sec / 100 cc / mil thickness. In one embodiment, the JIS Gurley number is in the range of 12 to 80 sec / 10 cc / mil.

[0254] According to some embodiments, the intrinsic viscosity (IV) of the film can be greater than or equal to 1.0 dl / g. In another embodiment, the IV can be greater than or equal to 5.0 dl / g. In another embodiment, the IV can preferably be greater than or equal to 3.0 dl / g. The IV of the thin film is not a weighted average of the pre-extruded resin that makes up the film, as the polymer undergoes chain scission during extrusion and the molecular weight is thereby reduced. As used herein, intrinsic viscosity refers to a measure of the ability of a polymer to increase the viscosity of a solution. The intrinsic viscosity number is defined as the extreme value of the specific viscosity / concentration ratio at zero concentration. Thus, it is necessary to find the viscosity at different concentrations and then extrapolate to zero concentration. The change in viscosity number with concentration depends on the type of molecule and the solvent. Generally, the intrinsic viscosity of linear macromolecular substances is related to the weight average molecular weight or degree of polymerization. For linear macromolecules, when the relationship between viscosity and molecular weight has been established, the viscosity number measurement can provide a system for rapid determination of molecular weight. IV is measured first by dissolving 0.02 g of the film in 100 ml of naphthalene at 150°C for 1 hour, and then determining its intrinsic viscosity at 135°C via a Ubbelohd viscometer. This is in accordance with ASTM D4020 (RSV values reported herein).

[0255] Shut down temperature can be less than 260°C (260 degrees Celsius). In one embodiment, the shut down temperature can be less than 10°C. In yet another embodiment, the shut down temperature can be less than 140°C. In still another embodiment, the shut down temperature can be less than 130°C. In still yet another embodiment, the shut down temperature can be less than 120°C.

[0256] The film can be made of a single polymer or a mixture of polymers or layers of the same or different polymers or layers of different materials bonded, laminated or co-extruded together. A possible preferred polymer is a polyolefin such as polypropylene (PP) and / or polyethylene (PE). For example, the film can be made of one or more layers of PP and / or PE. In one particular example, the film is a porous PP film or sheet. In another particular example, the film is a porous PE film or sheet. In still another particular example, the film is a three-layer film made of two outer PP layers and a middle or center PE layer. In another particular example, the film is a two-layer film made of two PP layers, two PE layers or one PP and one PE layer bonded together, laminated together or co-extruded together. In still another particular example, the film is a composite of a porous PP film or sheet and a porous material such as non-woven glass or a PP material. In still another particular example, the film is a porous film or sheet made of a mixture of polyolefins having different molecular weights.

[0257] According to at least selected embodiments, the gas filter media includes a microporous membrane. As used herein, gas filter media refers to filter media that removes particulates from a gas, such as air.

[0258] The gas filter media of the present utility model can include ultra-high molecular weight polyethylene and inorganic materials. The gas filter media can further include process oil (i.e., oil that remains in the media after extraction). The gas filter media can further include thermoplastic polyolefins, conventional additives such as stabilizers and antioxidants, and the like, as are widely known in the art.

[0259] The gas filter media can be used as filter media for any end-use application. For example, the gas filter media can be used as filter media for an end-use application selected from the group consisting of removing particulates from a gas, air filtration applications, elevated temperature applications, baghouse applications, particulate filtration in food and pharmaceuticals, particulate filtration in combustion processes, particulate filtration in metals, and particulate filtration in cement. Removing particulates from a gas includes industrial applications such as HVAC, HEPA and ULPA clean rooms, vacuum cleaning, breathing masks, cement, metals, food, pharmaceuticals, process fluids, and combustion processes.

[0260] The gas filter media can stand alone as the filter media; or in alternative embodiments, it can be combined (e.g., laminated or bonded to) with a support material such as a nonwoven material or fabric. Exemplary lamination or bonding techniques include such conventional systems as, but not limited to, adhesives, welding processes (thermal / ultrasonic), and the like. Further, the gas filter media can be flat or formed into pleats or shapes. There is a need for separators with more dimensional stability (or high temperature meltdown integrity) for larger batteries, as the rupture of the battery can be more pronounced if a short occurs, as larger batteries contain larger amounts of lithium material. Thus, according to at least some embodiments, the battery separator is made from a nonwoven flat sheet material with high temperature meltdown integrity, a microporous membrane with low temperature shutdown properties, and optionally an adhesive that bonds the nonwoven flat sheet to the microporous membrane and is adapted to swell when contacted by electrolyte. The high temperature meltdown integrity separator can include a microporous membrane and a nonwoven flat sheet bonded together with or without an adhesive or polymer in between. The nonwoven flat sheet can refer to a plurality of fibers bonded together by various systems such as thermal fusion, resin, solvent bonding, or mechanical interlocking of the fibers, sometimes in conjunction with their extrusion. The nonwoven flat sheet includes fiber structures made by processes such as dry, wet or air-laying, needle punching, spunbonding or melt blown processes, and hydroentangling. The fibers can be directional or randomly oriented. Although nonwovens generally do not include paper, for the purposes of this application, paper is included. The fibers can be made from thermoplastic polymers, cellulose, and / or ceramics. The thermoplastic polymers include, but are not limited to, polystyrenes, polyvinyl chlorides, polyacrylics, polyacetals, polyamides, polycarbonates, polyesters, polyetherimides, polyimides, polyketones, polyphenylene oxides, polyphenylene sulfides, and polysulfones. The cellulose includes, but is not limited to, cellulose (e.g., cotton or other naturally occurring sources), regenerated cellulose (e.g., rayon), and cellulose acetate (e.g., cellulose acetate and triacetate). The ceramics include, but are not limited to, all types of glass and aluminum oxide, silica, and zirconium oxide compounds (e.g., aluminum silicates).

[0261] Additionally, the nonwoven or fibers of the nonwoven can be coated or surface treated to improve the functionality of the nonwoven. For example, the coating or surface treatment can improve the adhesion of the nonwoven or its fibers, improve the high temperature meltdown integrity of the nonwoven, and / or improve the wettability of the nonwoven. With respect to improving the high temperature meltdown integrity, the nonwoven and / or its fibers can be coated or surface treated with a ceramic material. Such ceramic materials include, but are not limited to, aluminum oxide, silica, and zirconium oxide compounds, and combinations thereof.

[0262] According to at least selected embodiments, bonding the microporous membrane to the nonwoven flat sheet should maintain a high rate of discharge, which can require the presence of free migration of electrolyte ion species between the anode and the cathode. The mobility of the ion species is typically measured as the electrical resistance (ER) or the MacMullin number (the ratio of the resistance of a porous medium saturated with electrolyte to the resistance of an equal volume of electrolyte [see: U.S. Patent No. 4,464,238, incorporated herein by reference]). Thus, it can be desirable to bond the sheet to the membrane with a material that does not decrease the ion mobility (or increase the electrical resistance) across the separator.

[0263] The binder can be selected from, but not limited to, polyvinylidene fluoride (PVDF); polyurethane; polyethylene oxide (PEO); polyacrylonitrile (PAN); polymethyl acrylate (PMA); polymethyl methacrylate (PMMA); polyacrylamide; polyvinyl acetate; polyvinyl pyrrolidone; polybutylene diglycolate; copolymers of any of the foregoing; and combinations thereof. One criterion for the selection of a comonomer is the ability of the comonomer to change the surface energy of the homopolymer. Surface energy affects at least: the solubility of the copolymer, thereby affecting the ability to coat the copolymer on the membrane; the adhesion of the copolymer to the membrane, thereby affecting battery manufacturing and subsequent performance; and the wettability of the coating, thereby affecting the uptake of the liquid electrolyte into the separator. Suitable comonomers include, but are not limited to, hexafluoropropylene, octafluoro-l-butene, octafluoroisobutylene, and tetrafluoroethylene. The comonomer content is preferably in the range of 3% to 20% by weight, and most preferably 7% to 15%. Preferably, the binder or swellable polymer is a copolymer of polyvinylidene fluoride. Preferably, the PVDF copolymer is a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVDF:HFP), and most preferably, the ratio of PVDF:HFP is 91 :9. PVDF copolymers are commercially available from Elf Atochem of Philadelphia, PA; Solvay SA of Brussels, Belgium; and Kureha Chemical Industries, LTD of Ibaraki, Japan. The preferred PVDF:HFP copolymer is YNAR 2800 from Elf Atochem.

[0264] The humectant can be selected from materials that are compatible (i.e., miscible or will not phase separate) with the swellable polymer, present in trace amounts (e.g., 10-20% of the swellable polymer), will not adversely affect the battery chemistry (such as humectants containing sulfones, sulfates, and nitrogen), and are fluid or have a Tg (glass transition temperature) < 50°C at room temperature. The humectant can be selected from, but not limited to, phthalate-based esters, cyclic carbonates, polymeric carbonates, and mixtures thereof. The phthalate-based esters are selected from, but not limited to, dibutyl phthalate (DBP). The cyclic carbonates are selected from ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and mixtures thereof. The polymeric carbonates are selected from, but not limited to, polyvinylidene carbonate and linear propylene carbonate. The present invention can provide a microporous battery separator having two portions bonded together. Each portion can be composed of co-extruded or non-co-extruded layers and can be made of the same or different materials. To achieve greater breakdown strength, some embodiments can bond two portions of a specified size together, when bonded, having a desired total separator thickness. Selected embodiments can preferably be made by a bubble-popping technique, i.e., blown film technique, wherein a single molten polymer (or mixture of polymers) is extruded through an annular die, the bubble produced from the die having a first portion and a second portion (each portion representing substantially one-half of the circumference of the bubble), and the bubble subsequently pops on its own and bonds prior to micropore formation (preferably by annealing and stretching). When the bubble is produced from the die, it is substantially longitudinally oriented. Thus, when the bubble pops on its own and bonds, the first portion and the second portion can be oriented in substantially the same direction (with an angular skew between the oriented portions of less than 15°). By allowing the molten (or near molten) polymer of the bubble to weave together, the popping and bonding are performed in the same step. By the bubble popping on its own and bonding, increased breakdown strength is achieved over separators that can be equal in thickness. The first portion and the second portion, when bonded, provide a precursor for the micropore formation process (such as, for example, annealing and stretching operations), can be made of materials such as polyolefins, preferably polyethylene or polypropylene, copolymers thereof, and mixtures thereof, and most preferably polyethylene and polypropylene.

[0265] A three-layer, closed cell battery separator can refer to a porous film for use in an electrochemical cell, such as a battery, particularly a secondary (or rechargeable) battery, such as a lithium battery. The three-layer separator can have a polypropylene-polyethylene-polypropylene configuration. The separator can have a thickness of less than 3 mil (approximately 75 microns). The thickness of the separator is preferably in the range between 0.5 mil (approximately 12 microns) and 1.5 mil (approximately 38 microns). Most preferably, the thickness of the separator is approximately 1 mil (approximately 25 microns). Preferably, the separator has a permeability of less than 300 sec, as measured by JIS Gurley. Preferably, the separator has a puncture strength of at least 300 grams. Preferably, the separator has a porosity in the range of 40% to 70%. A system for manufacturing a three-layer, closed cell battery separator generally includes the steps of: extruding a non-porous polypropylene precursor; extruding a non-porous polyethylene precursor; forming a non-porous three-layer precursor, wherein the polyethylene precursor is sandwiched between the polypropylene precursors; bonding the three-layer precursor; annealing the three-layer precursor; and stretching the bonded and annealed non-porous three-layer precursor to form a porous battery separator.

[0266] In at least one embodiment, the film can be a microporous sheet made from a mixture of at least two ultra-high molecular weight polyolefins having different molecular weights. In one embodiment, the ultra-high molecular weight polyolefins can be ultra-high molecular weight polyethylenes (UHMWPEs). In another embodiment, the film is a mixture of a first ultra-high molecular weight polyethylene having a first molecular weight and a second ultra-high molecular weight polyethylene having a second molecular weight, the first and second molecular weights being greater than 1,000,000 and different from one another. In another embodiment, the film is a mixture of a first ultra-high molecular weight polyethylene having a first molecular weight, a second ultra-high molecular weight polyethylene having a second molecular weight, and a third polyolefin having a third molecular weight, the first and second molecular weights being greater than 1,000,000 and different from one another, and the third molecular weight being less than 1,000,000. In still another embodiment, the film can have an IV greater than or equal to 6.3 dl / g. In another embodiment, the film can have an IV greater than or equal to 7.7 dl / g. In at least selected embodiments, the present disclosure is directed to a machine direction and cross direction oriented porous film, a composite including a machine direction and cross direction oriented porous film, a machine direction and cross direction oriented microporous film, a machine direction and cross direction oriented macroporous film, a battery separator, a filtration medium, a humidity control medium, a flat sheet film, a liquid retention medium, etc., related systems, manufacturing systems, use systems, etc.

[0267] According to certain embodiments, laminated materials or fabrics can be incorporated into composite membranes manufactured according to the present application and which are resistant to wind and liquid penetration, moisture vapor permeable and air permeable. The laminated fabric can also include one or more layers of textile substrate or outer fabric material laminated to the membrane by any suitable process. The outer fabric material can be made of any suitable material that meets the performance and other criteria established for a given application.

[0268] "Moisture vapor permeable" is used to describe an article that allows water vapor to pass through the article, such as a laminated fabric or composite membrane. The term "resistant to liquid penetration" is used to describe an article that is not "wetted" or "drenched" by a liquid such as water, and prevents liquid penetration through the membrane under relatively low pressure environmental conditions. The term "resistant to wind penetration" describes the ability of an article to prevent air penetration greater than about three (3) CFM per square foot under a 0.5" water differential across the article.

[0269] For example, a jacket, coat or other garment or finished product incorporating a laminated fabric can allow moisture vapor to pass through the garment. The moisture vapor can be caused by perspiration of the user, and the garment or finished product preferably allows the moisture vapor to pass through during use under typical conditions at a rate sufficient to keep the user dry and comfortable. The laminated fabric is also preferably resistant to liquid and wind penetration, while being air permeable.

[0270] According to the present application, an air filter cartridge includes at least one pleated microporous membrane.

[0271] At least one selected microporous membrane is made by a dry stretching process and has substantially circular pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 6.0. A system for making the foregoing microporous membrane can include the steps of extruding a polymer as a non-porous precursor, and stretching the non-porous precursor in the cross direction, the cross direction stretching including simultaneous controlled machine direction relaxation.

[0272] The present application relates to cross-laminate porous membranes, composite materials including cross-laminate porous membranes, cross-laminate microporous membranes, cross-laminate macroporous membranes, battery separators, filtration media, humidity control media, flat sheet membranes, liquid retention media, and the like.

[0273] According to the present application, a membrane is provided, comprising: at least one porous polymeric film made by a dry stretching process comprising the steps of: extruding a polymer into at least one single layer of non-porous precursor, and stretching the non-porous precursor in both the machine direction and the cross direction, the stretching in both the machine direction and the cross direction comprising simultaneous controlled relaxation in the machine direction, and having substantially circular pores, a porosity of about 40% to 90%, a ratio of machine direction tensile strength to cross direction tensile strength ranging from about 0.5 to 5.0, a Gurley of less than about 100, an average flow pore size of at least about 0.04 microns, an Aquapore pore size of at least about 0.07 microns, and a head pressure of greater than about 140 psi.

[0274] Preferably, the stretching in the machine direction of the stretching in both the machine direction and the cross direction comprises a step of simultaneous cross direction stretching of the machine direction stretching, and wherein the stretching in both the machine direction and the cross direction further comprises a step of cross direction relaxation; the stretching in both the machine direction and the cross direction of the non-porous precursor further comprises an additional step of machine direction stretching; the dry stretching process further comprises the step of machine direction stretching to form a porous intermediate prior to the stretching in both the machine direction and the cross direction; the stretching in both the machine direction and the cross direction of the non-porous precursor comprises machine direction stretching, additional cross direction stretching simultaneous with the machine direction stretching, and cross direction relaxation; the dry stretching process comprises the steps of machine direction stretching, followed by the stretching in both the machine direction and the cross direction comprising the cross direction stretching simultaneous with controlled relaxation in the machine direction, a second cross direction stretching simultaneous with the machine direction stretching, followed by cross direction relaxation; the porous polymeric film further has a thickness of at least about 8 microns, a cross direction tensile strength of at least about 300 kgf / cm 2 2 ​- a WVTR of at least about 0.01 g / m2 / 24 hrs; the porous polymeric film further having a transverse shrinkage of less than about 1.0% at 90°C; the porous polymeric film further having a transverse shrinkage of less than about 1.5% at 105°C; the porous polymeric film further having a transverse shrinkage of less than about 3.0% at 120°C; the porous polymeric film further having a machine direction shrinkage of less than about 10% at 90°C; the porous polymeric film further having a machine direction shrinkage of less than about 20% at 105°C; the porous polymeric film further having a machine direction shrinkage of less than about 30% at 120°C; the porous polymeric film further having a thickness ranging from about 8 microns to 80 microns; the non-porous precursor being one of a blown film and a slot die film; the non-porous precursor being a single layer precursor formed from at least one of a single layer extrusion and a multi-layer extrusion; the non-porous precursor being a multi-layer precursor formed from at least one of a co-extrusion and a lamination; the porous polymeric film comprising one of a polypropylene, a polyethylene, mixtures thereof, and combinations thereof; the porous polymeric film using a polyolefin resin having a melt flow index (MFI) of about 0.01 to 10.0 and a polymer crystallinity of at least about 45%; the precursor being one of a single layer precursor and a multi-layer precursor; the film further comprising at least one non-woven, woven or knitted layer bonded to at least one side of the porous polymeric film; the film consisting of a plurality of the porous polymeric films; the porous polymeric film consisting of at least two layers; the film having substantially circular pores, a porosity of about 40% to 90%, a ratio of machine direction tensile strength to transverse tensile strength ranging from about 0.5 to 5.0, a Gurley of less than about 100, an average flow pore size of at least about 0.04 microns, an Aquapore pore size of at least about 0.07 microns, and a hydrohead pressure of greater than about 140 psi; the polymer being a semi-crystalline polymer; the polymer being selected from the group consisting of a polyolefin, a fluorocarbon, a polyamide, a polyester, a polyacetal (or polyformal), a polysulfide, a polyphenylene sulfide, a polyvinyl alcohol, copolymers thereof, mixtures thereof, and combinations thereof; the porous polymeric film further having a porosity of about 65% to 90%, a ratio of machine direction tensile strength to transverse tensile strength ranging from about 1.0 to 5.0, a Gurley of less than about 20, an average flow pore size of at least about 0.05 microns, an Aquapore pore size of at least about 0.08 microns, and a hydrohead pressure of greater than about 145 psi; or, the substantially circular pores having at least one of an aspect ratio ranging from about 0.75 to 1.25 and a sphericity coefficient ranging from about 0.25 to 8.0.

[0275] The present utility model includes at least one of the above membranes: a filtration membrane, a humidity control membrane, a gas and / or liquid separation membrane, a membrane that selectively passes moisture and blocks liquid water, and a multi-layer membrane structure.

[0276] Preferably, the longitudinal and transverse stretching step of the dry stretching process includes simultaneously stretching multiple individual, stacked, layers or sheets of the non-porous precursor in both longitudinal and transverse directions, wherein no sheets are bonded together during the stretching process; the longitudinal and transverse stretching step of the dry stretching process includes simultaneously stretching at least three individual stacked layers of the non-porous precursor in both longitudinal and transverse directions; the longitudinal and transverse stretching step of the dry stretching process includes simultaneously stretching at least eight individual stacked layers of the non-porous precursor in both longitudinal and transverse directions; the longitudinal and transverse stretching step of the dry stretching process includes simultaneously stretching multiple combined stacked layers or sheets of the non-porous precursor in both longitudinal and transverse directions, wherein all sheets are bonded together during the stretching process; the longitudinal and transverse stretching step of the dry stretching process includes simultaneously stretching multiple individual stacked layers or sheets of the non-porous precursor in both longitudinal and transverse directions, and multiple combined stacked layers or sheets of the non-porous precursor, some of which are bonded together during the stretching process; or, the extrusion step is a dry extrusion process using an extruder having at least one of a slot die and an annular die.

[0277] The battery separator of this utility model includes: at least one porous polymer film, which is formed by a dry stretching process including the following steps:

[0278] The polymer is extruded into at least a monolayer nonporous precursor, and the nonporous precursor is stretched longitudinally and transversely, the stretching including longitudinal stretching and transverse stretching, the transverse stretching including simultaneously controlled longitudinal relaxation, and having substantially circular pores, a porosity of about 40% to 70%, a longitudinal tensile strength to transverse tensile strength ratio ranging from about 0.5 to 5.0, a Gurley of less than about 300, an average flow pore size of at least about 0.01 micrometers, and an Aquapore pore size of at least about 0.04 micrometers.

[0279] Preferably, the at least one porous polymer film further has a thickness of at least about 8 micrometers and a density of at least about 300 kgf / cm². 2The transverse tensile strength is less than about 0.025 of the average flow rate orifice diameter standard deviation; the at least one porous polymer film further has a transverse shrinkage of less than about 2% at 90°C; the at least one porous polymer film further has a longitudinal shrinkage of less than about 6% at 90°C; the non-porous precursor is formed by at least one of single-layer extrusion and multi-layer extrusion; the non-porous precursor is a multi-layer precursor formed by at least one of co-extrusion and lamination; the separator is composed of a plurality of the porous polymer films; the polymer is selected from polyolefins, fluorocarbons, polyamides, polyesters, polyacetals (or polyoxymethylene), polysulfides, polyphenylene sulfides, polyvinyl alcohol, copolymers thereof, mixtures thereof, and combinations thereof; or the substantially circular pores have at least one of an aspect ratio ranging from about 0.75 to 1.25 and a sphericity coefficient ranging from about 0.25 to 8.0.

[0280] The porous membrane of this invention comprises: at least one porous polymer film, which is made by a dry stretching process including the following steps: extruding a polymer into at least one monolayer non-porous precursor, and stretching the non-porous precursor longitudinally and transversely, the longitudinal and transverse stretching including longitudinal stretching and transverse stretching, the transverse stretching including simultaneously controlled longitudinal relaxation, and having substantially circular pores, a porosity of at least about 40%, a longitudinal tensile strength to transverse tensile strength ratio ranging from about 0.5 to 5.0, a Gurley strength of less than about 300, an average flow pore size of at least about 0.01 micrometers, and an Aquapore pore size of at least about 0.04 micrometers.

[0281] This utility model relates to at least one of the following: battery separator, filter membrane, humidity control membrane, gas and / or liquid separation membrane, membrane that selectively allows moisture to pass through and blocks liquid water, and multilayer membrane structure.

[0282] This invention improves upon the following: in devices requiring humidity control, in filtration devices, and in temperature-affected devices, by including the above-mentioned membranes.

[0283] The present invention provides a system for manufacturing microporous membranes, comprising the following steps: extruding a polymer into a non-porous precursor, and stretching the non-porous precursor longitudinally and transversely, wherein the stretching includes longitudinal stretching and transverse stretching, and the transverse stretching includes simultaneously controlled longitudinal relaxation.

[0284] Preferably, the polymer excludes any oil that is subsequently removed to form pores or any pore-forming material to facilitate pore formation; the polymer is a semi-crystalline polymer; the polymer is selected from polyolefins, fluorocarbons, polyamides, polyesters, polyacetals (or polyoxymethylene), polysulfides, polyvinyl alcohol, copolymers thereof, and combinations thereof; further comprising the steps of: annealing the non-porous precursor after extrusion and before longitudinal and transverse stretching; annealing at T m -80℃ to T m- performed at temperatures in the range of 10°C; the stretch-to-elongate includes the following steps: stretch-to-elongate in the machine direction, and thereafter a stretch-to-elongate in the cross direction including simultaneous relaxation in the machine direction; the stretch-to-elongate in the machine direction is performed hot or cold or both; the cold stretch-to-elongate in the machine direction is performed at temperatures < T m - performed at temperatures < 50°C; the hot stretch-to-elongate in the machine direction is performed at temperatures < T m - performed at temperatures < 10°C; the total stretch-to-elongate in the machine direction is in the range of 50-500%; the total stretch-to-elongate in the cross direction is in the range of 100-1200%; or, the relaxation in the machine direction is in the range of 5-80%.

[0285] The film of the present invention comprises: a microporous polymeric film made by a dry stretch process and having substantially circular pores and a ratio of machine direction tensile strength to cross direction tensile strength in the range of 0.5 to 6.0.

[0286] Preferably, the microporous polymeric film has an average pore size in the range of 0.03 to 0.30 microns; the microporous polymeric film has a porosity in the range of 20-80%; the substantially circular pores have at least one of an aspect ratio in the range of about 0.75 to 1.25 and a sphericity factor in the range of about 0.25 to 8.0; or, the cross direction tensile strength is > 250 Kg / cm 2 .

[0287] The present invention is a battery separator comprising the above film, a multi-layer film structure comprising the above film, or an air filter cartridge comprising the above film.

[0288] In a system for filtering particulates from a gas, the improvement comprises the above film, or a gas filter medium comprising the above film.

[0289] A battery separator comprising: a non-woven flat sheet having high temperature melt integrity; and the above film.

[0290] A battery made with the above separator.

[0291] In a porous film, the improvement comprises at least one of: a pore shape that is not a slit, a circular pore, such as those shown in one of Figures 6-8 and 13-54, such as Figures 13-50those pores shown in one of Figures 6-8 and 13-50, the properties shown in one of Tables I, II or III, increased cross-directional tensile strength, balance of MD and TD physical properties, high performance related to water vapor transport and head pressure, reduced Gurley, high porosity with balanced physical properties, uniformity of pore structure including pore size and pore size distribution, improved durability, composites of such films with other porous materials, composites or laminates of such films, membranes or layers with porous nonwovens, coated films, co-extruded films, laminated films, films having desirable water vapor transport or moisture transport, head performance and physical strength properties, usefulness in more physically adverse environments without loss of desirable film characteristics, combination of film water vapor transport performance coupled with macroscopic physical properties, are hydrophobic, highly permeable, chemically and mechanically stable, have high tensile strength, and combinations thereof.

[0292] At least one selected microporous membrane is made by a dry stretching process and has substantially circular pores and a ratio of machine direction tensile strength to cross direction tensile strength in the range of 0.5 to 6.0. A system for making the foregoing microporous membranes can include the steps of extruding a polymer into a non-porous precursor, and stretching the non-porous precursor in the machine and cross directions, the cross direction stretching including simultaneous controlled machine direction relaxation. At least one selected embodiment of the present invention can be directed to machine and cross direction oriented porous membranes, composites including machine and cross direction oriented porous membranes, machine and cross direction oriented microporous membranes, machine and cross direction oriented macroporous membranes, battery separators, filtration media, humidity control media, flat sheet membranes, liquid retention media, and the like.

[0293] The present invention can take other forms without departing from its spirit and nature and, therefore, the scope of the present invention should be defined with reference to the appended claims rather than the foregoing description.

[0294] Further, all numerical ranges herein should be considered approximately and not necessarily absolutely.

Claims

1. A porous membrane for fluid mass transfer and / or filtration, characterized in that, It has a porosity of 40% to 90%, an average flow pore size of at least 0.04 microns, an Aquapore pore size of at least 0.07 microns in size, and a sphericity coefficient of 0.25 to 8.0; at least one of the porous membranes is a circular microporous membrane; the porous membrane has a thickness of 8 microns to 80 microns, and is rolled into a cylindrical shape after being pleated by itself.

2. A porous membrane having a plurality of layers, the layers being connected by respective extrusion re-laminations or directly interfacing by co-extrusion, obviating the need for adhesive layers, for fluid mass transfer and / or filtration, characterised in that, At least one layer is a circular microporous membrane; It is repeatedly folded in a Z shape, wound into a reel, pleated and folded, and / or packed into a bag; each layer has a porosity of 40% to 90%, an average flow pore size of at least 0.04 microns, an Aquapore pore size of at least 0.07 microns in size, and a sphericity coefficient of 0.25 to 8.0; the porous membrane has a thickness of 8 microns to 80 microns.

3. The porous membrane according to claim 1 or 2, wherein The outermost surface of the porous membrane has "mouth-shaped" and "hollow-shaped" ribs / grooves at the edge adjacent to the edge; or, the porous membrane has at least two outer layers and at least one inner layer; the outer layer has a first interface facing the inner layer, and the inner layer has a second interface facing the outer layer; the first interface and the second interface are embedded with each other; the outer layer and the inner layer are automatically directly integrated into one body during the co-extrusion process; the outer layer and the inner layer have circular micropores formed by a dry stretching process.

4. The porous membrane according to claim 1 or 2, wherein The porous membrane is a filtration membrane, a mass transfer membrane, a humidity control membrane, a gas and / or liquid phase separation membrane, a single / multi-layer membrane for selectively passing moisture and blocking water in liquid, or a propylene-based HEPA / ULPA membrane; or, the porous membrane is used in a humidity control device, a device for selectively passing moisture and blocking water in liquid, a pressure regulator, a medical device, a battery separator, or a fuel cell.

5. A fluid sorter, comprising: The fluid sorter (100) has an outer cylinder (110) and an inner cylinder (154); the surface of the inner cylinder has an array of holes in communication with the outer cylinder; the two ends of the outer cylinder have a left end cover (116) and a right end cover (118) closing the annular space (130) between the outer cylinder and the inner cylinder, and a left inner cylinder port (113) and a right inner cylinder port (114); the outer cylinder has two left outer cylinder ports (124) and right outer cylinder ports (126) of the annular space between the outer cylinder and the inner cylinder; the outer cylinder and the inner cylinder are divided into several sorting cavities (196, 198) along the axial direction; each sorting cavity has a porous membrane as claimed in claim 1 or 2 wrapped around the outer surface of the inner cylinder in the annular space, and the two end walls of the sorting cavity are provided with turbulence ports (155) offset from each other.

6. An apparatus for producing a porous membrane, characterized by comprising: The porous membrane is as claimed in claim 1 or 2; the preparation apparatus comprises: a first device (10) for extruding a polymer into a non-porous intermediate; and a second device (20) for longitudinally and transversely stretching the non-porous intermediate, the second device being located downstream of the first device; the second device comprises a third device (30) for implementing longitudinal stretching of the non-porous intermediate, and a fourth device (40) for implementing transverse stretching of the non-porous intermediate; the fourth device comprises a fifth device (50) that is interrelated with the third device, such that the non-porous intermediate is subjected to a proportionally limited or degree-controlled longitudinal retraction while being transversely stretched.

7. The preparation apparatus according to claim 6, wherein The fourth device (40) comprises a pair of first rotating rollers (41) arranged transversely for initially clamping side edges of the elongating non-porous intermediate, a plurality of pairs of second rotating rollers (42) arranged transversely for clamping the side edges of the elongating non-porous intermediate, and a pair of third rotating rollers (43) arranged transversely for releasing the side edges of the elongating non-porous intermediate; the first rotating rollers (41) and the third rotating rollers (43) are coordinated to operate in reverse through a reverser (44); the second rotating rollers (42) keep clamping the side edges of the elongating non-porous intermediate through an electronic brake controller (46); the first rotating rollers (41), the second rotating rollers (42), and the third rotating rollers (43) clamp the side edges of the elongating non-porous intermediate throughout the length; a proportion controller (45) is provided between the fourth device (40) and the fifth device (50).

8. The preparation apparatus according to claim 6, wherein The third device (30) and the fifth device (50) have the same radius, the third device (30) is driven to rotate at a speed V1, the fifth device (50) is driven to rotate at a speed V2, V2 < V1; and / or, the first rotating rollers (41) and / or at least one second rotating roller (42) are driven to rotate at a speed V3, the third rotating rollers (43) are driven to rotate at a speed V4, V4 < V3.

9. The preparation apparatus according to claim 7, wherein The axes of the first rotating rollers (41), the second rotating rollers (42), and the third rotating rollers (43) are all perpendicular to the stretching direction (X) and are arranged at an acute angle with the fourth device (40).

10. The preparation apparatus according to claim 6, wherein Between the first device (10) and the second device (20), a non-porous intermediate passage section (15) is provided, which is provided with a non-porous intermediate passage controller (14) having an open state and a closed state, in the open state, a plurality of pairs of passage rollers (12) with axes perpendicular to the stretching direction (X) are out of contact with the non-porous intermediate section (11); in the closed state, the plurality of pairs of passage rollers (12) clamp the two side edges of the non-porous intermediate section (11).

11. The preparation apparatus according to claim 6, wherein Between the first device (10) and the second device (20), a sixth device for annealing the non-porous intermediate after extrusion and before longitudinal and transverse stretching of the non-porous intermediate is also provided; and / or, the third device is provided with a seventh device for controlling the stretching temperature. The porous membrane is as claimed in claim 1 or 2; the preparation apparatus comprises: a first device (10) for extruding a polymer into a non-porous intermediate; and a second device (20) for longitudinally and transversely stretching the non-porous intermediate, the second device being located downstream of the first device; the second device comprises a third device (30) for implementing longitudinal stretching of the non-porous intermediate, and a fourth device (40) for implementing transverse stretching of the non-porous intermediate; the fourth device comprises a fifth device (50) that is interrelated with the third device, such that the non-porous intermediate is subjected to a proportionally limited or degree-controlled longitudinal retraction while being transversely stretched.

12. The preparation apparatus according to claim 6, wherein The third device is provided with an eighth device for controlling the longitudinal stretching range to be 50-500%; the fourth device is provided with a ninth device for controlling the transverse stretching range to be 100-1200%; and / or, the fifth device is a device for controlling the longitudinal shrinkage to be in the range of 5-80%.

13. The preparation apparatus according to claim 12, wherein The fifth device is a device for controlling the longitudinal shrinkage to be in the range of 15-65%.

14. The manufacturing apparatus of claim 13, wherein The fifth device is a device for controlling the longitudinal shrinkage to be in the range of 59-75%.

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