Microporous membrane for breathable fabric and preparation method therefor, and breathable fabric

Abstract

The present application relates to a microporous membrane for a breathable fabric and a preparation method therefor, and a breathable fabric. The microporous membrane for a breathable fabric comprises an ionic liquid. The mass percentage of the ionic liquid in the microporous membrane is 0.01% to 6%, and the air permeability is 10 sec / 100 cc to 60 sec / 100 cc. The ionic liquid comprises a first ionic liquid, which has a hydrophilic-lipophilic balance value of less than 10.

Description

Microporous membranes for breathable fabrics and their preparation methods and breathable fabrics

[0001] Related applications

[0002] This application claims priority to PCT international patent application filed on January 24, 2025, with application number PCT / CN2025 / 074895, entitled "Microporous membranes and their preparation methods and applications", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of microporous membranes, and in particular to a microporous membrane for breathable fabrics, a method for preparing the same, and the breathable fabric. Background Technology

[0004] The following statements are intended to provide background information in connection with this application and do not necessarily constitute prior art.

[0005] Currently, microporous membranes struggle to meet the increasingly demanding market requirements for membrane products. For example, in the apparel fabric industry, microporous membranes are required to possess excellent pore structure, mechanical strength, and thickness to satisfy the fabric's requirements for comfort, waterproofing, and high moisture permeability. Therefore, there is an urgent need to develop a microporous membrane that can meet the market requirements of these fields and possesses excellent overall performance. Summary of the Invention

[0006] Based on this, some embodiments of this application provide a microporous membrane for breathable fabrics, which has good comprehensive performance to meet the requirements for good application of the membrane in the field of clothing fabrics.

[0007] In addition, some other embodiments of this application also provide a method for preparing a microporous membrane for breathable fabrics and a breathable fabric.

[0008] A microporous membrane for breathable fabrics, the microporous membrane containing an ionic liquid, wherein the mass percentage of the ionic liquid in the microporous membrane is 0.01% to 6%, the breathability of the microporous membrane is 10 sec / 100cc to 60 sec / 100cc, and the ionic liquid includes a first ionic liquid, wherein the hydrophilic-lipophilic balance value of the first ionic liquid is <10.

[0009] In some embodiments, the hydrophilic-lipophilic balance value of the first ionic liquid is 0 to 9.8, and can be selected as 3 to 7.

[0010] In some embodiments, the molecular weight of the first ionic liquid is 200 to 1000.

[0011] In some embodiments, the boiling point of the first ionic liquid is 200°C to 500°C.

[0012] In some embodiments, the viscosity of the first ionic liquid at 25°C is 20cp to 100cp.

[0013] In some embodiments, the mass percentage of the first ionic liquid in the microporous membrane is 0.01% to 6%.

[0014] In some embodiments, the mass percentage of the first ionic liquid in the microporous membrane is 0.1% to 5%.

[0015] In some embodiments, the microporous membrane further contains a second ionic liquid, the second ionic liquid having a hydrophilic-lipophilic balance value greater than that of the first ionic liquid.

[0016] In some embodiments, the molecular weight of the second ionic liquid is smaller than that of the first ionic liquid.

[0017] In some embodiments, the difference between the hydrophilic-lipophilic balance value of the second ionic liquid and the hydrophilic-lipophilic balance value of the first ionic liquid is <10.

[0018] In some embodiments, the hydrophilic-lipophilic balance value of the second ionic liquid is 10 to 20.

[0019] In some embodiments, the molecular weight of the second ionic liquid is 100 to 250.

[0020] In some embodiments, the boiling point of the second ionic liquid is 100°C to 500°C.

[0021] In some embodiments, the viscosity of the second ionic liquid at 25°C is 10 cp to 50 cp.

[0022] In some embodiments, the viscosity of the second ionic liquid at 25°C is 5 cp to 20 cp lower than that of the first ionic liquid at 25°C.

[0023] In some embodiments, the mass percentage of the second ionic liquid in the microporous membrane is 0.01% to 3%.

[0024] In some embodiments, the mass percentage of the second ionic liquid is 0.1% to 0.5%.

[0025] In some embodiments, the first ionic liquid and the second ionic liquid are each independently selected from one or more of imidazole salts, pyridine salts, quaternary ammonium salts, quaternary phosphonium salts, and pyrrolidines.

[0026] In some embodiments, the first ionic liquid and the second ionic liquid are each independently selected from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methyl sulfate, 1,3-dimethylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium tetrafluoroborate, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium trifluoromethanesulfonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium perchlorate, 1,3-dimethylimidazolium One or more of the following: nitrates, 1,3-dimethylimidazolium methanesulfonate, 1,3-dimethylimidazolium p-toluenesulfonate, 1,3-dimethylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, ethyl 1-ethyl-3-methylimidazolium sulfate, methyl 1-ethyl-3-methylimidazolium sulfate, diethyl 1-ethyl-3-methylimidazolium phosphate, dimethyl 1-ethyl-3-methylimidazolium phosphate, tetrafluoroborate, hexafluorophosphate, and antimonylate.

[0027] In some embodiments, the microporous membrane includes homopolymers or copolymers of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and norbornene, thermoplastic polyurethane elastomers, polyolefin elastomers, polyethylene terephthalate, polyurethane, or a mixture of polymers thereof.

[0028] In some embodiments, the microporous membrane comprises one or more of polyethylene, polypropylene, and ethylene-propylene copolymer.

[0029] In some embodiments, the viscosity-average molecular weight of the microporous membrane is 100,000 to 900,000.

[0030] In some embodiments, the microporous membrane further contains additives, including one or more of antioxidants, metal soaps, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments.

[0031] In some embodiments, the additive accounts for 0.01% to 5% of the total mass of the microporous membrane.

[0032] In some embodiments, the additive accounts for 0.1% to 1% of the total mass of the microporous membrane.

[0033] In some embodiments, the microporous membrane comprises multiple layers of sub-membranes stacked together, with different polymers in adjacent sub-membranes, and both containing the first ionic liquid.

[0034] In some embodiments, the average pore size of the microporous membrane is 20 nm to 200 nm.

[0035] In some embodiments, the average pore size of the microporous membrane is 60 nm to 200 nm.

[0036] In some embodiments, the transverse tensile strength of the microporous membrane is 500 kgf / cm². 2 ~5000 kgf / cm 2 .

[0037] In some embodiments, the longitudinal tensile strength of the microporous membrane is 1000 kgf / cm². 2 ~5000 kgf / cm 2 .

[0038] In some embodiments, the puncture strength of the microporous membrane is 150 gf to 400 gf.

[0039] In some embodiments, the porosity of the microporous membrane is 10% to 90%.

[0040] In some embodiments, the porosity of the microporous membrane is 60% to 90%.

[0041] In some embodiments, the thickness of the microporous membrane is 2 μm to 120 μm.

[0042] In some embodiments, the thickness of the microporous membrane is 3 μm to 20 μm.

[0043] A method for preparing a microporous membrane for breathable fabrics includes the following steps:

[0044] A mixture comprising polymer and ionic liquid is mixed, extruded, and cooled to form an intermediate film.

[0045] The intermediate membrane is stretched, extracted, and heat-set to obtain the microporous membrane.

[0046] The ionic liquid in the microporous membrane has a mass percentage of 0.01% to 6%, the air permeability of the microporous membrane is 10 sec / 100cc to 60 sec / 100cc, and the ionic liquid includes a first ionic liquid with a hydrophilic-lipophilic balance value of <10.

[0047] In some embodiments, the hydrophilic-lipophilic balance value of the first ionic liquid is 0 to 9.8, and can be selected as 3 to 7.

[0048] In some embodiments, the molecular weight of the first ionic liquid is 200 to 1000.

[0049] In some embodiments, the boiling point of the first ionic liquid is 200°C to 500°C.

[0050] In some embodiments, the mass ratio of the polymer to the ionic liquid is (5-60):(40-95).

[0051] In some embodiments, the extractant in the extraction step includes dichloromethane; or...

[0052] In the extraction step, the extractant includes a mixed solvent of a second ionic liquid and water, wherein the hydrophilic-lipophilic balance value of the second ionic liquid is greater than that of the first ionic liquid.

[0053] In some embodiments, the difference between the hydrophilic-lipophilic balance value of the second ionic liquid and the hydrophilic-lipophilic balance value of the first ionic liquid is <10.

[0054] In some embodiments, the hydrophilic-lipophilic balance value of the second ionic liquid is 10 to 20.

[0055] In some embodiments, the molecular weight of the second ionic liquid is smaller than that of the first ionic liquid.

[0056] In some embodiments, the molecular weight of the second ionic liquid is 100 to 250.

[0057] In some embodiments, the boiling point of the second ionic liquid is 100°C to 500°C.

[0058] In some embodiments, the viscosity of the second ionic liquid at 25°C is 10 cp to 50 cp.

[0059] In some embodiments, the viscosity of the second ionic liquid at 25°C is 5 cp to 20 cp lower than that of the first ionic liquid at 25°C.

[0060] In some embodiments, the extractant comprises a mixed solvent of a second ionic liquid and water, wherein the mass percentage concentration of the second ionic liquid in the extractant is 5% to 10%.

[0061] In some embodiments, after the extraction step, the process further includes washing the extracted microporous membrane intermediate with water, separating it with a reverse osmosis membrane, and drying it.

[0062] In some embodiments, the water washing of the extracted microporous membrane intermediate includes a first-stage water wash and a second-stage water wash. The mass percentage concentration of the second ionic liquid in the water used for the first-stage water wash is 3% to 5%, and the mass percentage concentration of the second ionic liquid in the water used for the second-stage water wash is not higher than 1%, and the mass percentage concentration of the second ionic liquid in the water used for the second-stage water wash is not higher than 30 wt% of the mass percentage concentration of the second ionic liquid in the water used for the first-stage water wash.

[0063] In some embodiments, the temperature T of the mixed extrusion 挤 For T 挤 =Polymer melting point T m +(15℃~60℃).

[0064] In some of these embodiments, T 挤 =Polymer melting point T m +(15℃~45℃).

[0065] In some embodiments, in the step of mixing and extruding a mixture comprising a polymer and an ionic liquid, the melt index of the polymer is 0.6 g / 10 min to 10 g / 10 min.

[0066] In some embodiments, the melt index of the polymer is 1.3 g / 10 min to 6 g / 10 min.

[0067] A breathable fabric, the breathable fabric comprising the microporous membrane described above or a microporous membrane prepared by the preparation method described above.

[0068] The microporous membranes of some embodiments of this application have a suitable ionic liquid content, which enables the microporous membrane to maintain good air permeability, tensile strength and heat shrinkage. When applied to the field of clothing fabrics, the microporous membranes with a suitable ionic liquid content can enable the fabric to have both good air permeability and moisture permeability and suitable oil absorption performance, thereby improving the use effect of the fabric.

[0069] The above-mentioned method for preparing microporous membranes uses ionic liquids, which have good compatibility with various polymers and can be applied to more polymer systems. Furthermore, the microporous membranes prepared by this method have better performance. Attached Figure Description

[0070] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the disclosed drawings without creative effort.

[0071] Figure 1 is a scanning electron microscope image (magnification 20Kx) of a polyethylene microporous membrane prepared using a conventional process.

[0072] Figure 2 is a scanning electron microscope image (magnification 20Kx) of a polyethylene microporous membrane according to an embodiment of this application. Detailed Implementation

[0073] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0074] The preferred embodiments of this application are given in the detailed description. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0076] Unless otherwise stated or in case of conflict, the terms or phrases used in this application shall have the following meanings:

[0077] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0078] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0079] In this application, "one or more" refers to any one, two, or more of the listed items. "Multiple" refers to any two or more of the listed items.

[0080] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0081] In this application, terms such as "further," "even more," "particularly," "for example," "like," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later, but should not be construed as limiting the preceding technical solution or restricting the scope of protection herein. Unless otherwise specified herein, A (e.g., B) indicates that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0082] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "present" or "absent." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. In this application, descriptions such as "optionally contains" and "optionally includes" indicate "contains or does not contain." "Optional component X" indicates whether component X exists or does not exist, or whether component X is contained or not.

[0083] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0084] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0085] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this application, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0086] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0087] In this application, a microporous membrane refers to a membrane formed having a large number of micropores on its surface and interior, with at least some of the micropores being interconnected, allowing gas or liquid to pass through from one surface of the membrane to the other. The “surface” of the membrane refers to the surface with the largest surface area.

[0088] Currently, microporous membranes are struggling to meet the increasingly demanding requirements of the market for membrane products. For example, in the field of apparel fabrics, comprehensive performance requirements for microporous membranes, such as thickness, porosity, air permeability, and mechanical strength, have been put forward. Therefore, there is an urgent need to develop a microporous membrane that can meet the market requirements of the above fields.

[0089] Researchers have creatively discovered that the overall performance of microporous membranes currently obtained in industrial applications is difficult to improve significantly. One reason is the limitation of current preparation processes, which mainly include wet and dry processes. The wet process employs thermally induced phase separation, requiring good compatibility between the pore-forming agent and the film-forming substrate. Currently, the widely used pore-forming agent in industrial applications is paraffin oil, which is compatible with polyethylene (PE) as the substrate material. However, it is difficult to adapt to other polymer materials and apply them to industrial production. This is because the current paraffin oil co-extrusion system cannot meet the requirements for uniform mixing with polymer melts from different systems to obtain high-quality intermediate films. For example, a melt mixture of PE and paraffin oil with a low melt index (below 0.6 g / 10 min, 190℃, 2.16 kg) (PE mass percentage of the melt is 30%, also known as melt solids content) has poor melt flowability and cannot meet the requirements for cooling and film formation, thus failing to produce qualified, high-quality membrane products. To increase fluidity, current solutions often involve reducing the melt solids content to below 15%. This leads to a significant amount of paraffin oil seeping out during phase separation, affecting subsequent manufacturing processes such as unstable or ineffective stretching. The resulting membranes are of extremely poor quality and fail to meet application requirements. Another solution is to continuously increase the extrusion temperature to improve melt fluidity; however, this causes polymer molecule degradation and paraffin oil volatilization, resulting in products that do not meet requirements. Dry processes are applicable to a wider range of polymer systems compared to wet processes, but microporous membranes produced by dry processes generally exhibit inferior heat resistance, thickness, pore size uniformity, and permeability compared to those produced by wet processes. For example, microporous membranes produced by dry uniaxial stretching have poor transverse strength, poor consistency, difficulty in achieving thinner membranes, and higher permeability. The dry biaxial stretching process has very high requirements for the preparation environment. If environmental control and the control of dust and burrs on the electrode are insufficient, the resulting microporous membrane will have a high short-circuit rate. Moreover, because this process is difficult to control the pore size, it is prone to uneven pore size distribution. Therefore, the performance improvement of microporous membranes obtained in current industrial applications is very limited. Traditional processes face significant limitations in ensuring that microporous membranes have a thin thickness range while also maintaining various properties such as mechanical strength.

[0090] Based on this, this application provides a microporous membrane with good overall performance, and a preparation method for obtaining a microporous membrane with good overall performance that is suitable for industrialization.

[0091] In a first aspect, this application provides a microporous membrane for breathable fabrics, which contains an ionic liquid. The mass percentage of the ionic liquid in the microporous membrane is 0.01% to 6%, and the breathability of the microporous membrane is 10 sec / 100cc to 60 sec / 100cc. The ionic liquid includes a first ionic liquid, and the hydrophilic-lipophilic balance value of the first ionic liquid is <10.

[0092] Microporous membranes with appropriate ionic liquid content maintain good air permeability, tensile strength, and heat shrinkage. When applied to clothing fabrics, microporous membranes with appropriate ionic liquid content can enable fabrics to have both good air permeability and moisture permeability, as well as suitable oil absorption properties, thereby improving the performance of the fabric.

[0093] The first ionic liquid is an ionic salt that is liquid below 100°C. The first ionic liquid can form a homogeneous phase with the polymer under high temperature conditions. Below 100°C, it will separate into an ionic liquid and a polymer solid phase, which is beneficial for preparation methods applicable to different polymer systems and can obtain microporous membranes with good uniformity.

[0094] The microporous membrane contains several fibrils, which are interwoven to form pores. Ionic liquids adhere to the surface of the fibrils inside the microporous membrane through their oleophilic ends. The fibrils in the microporous membrane are obtained by stretching and oriented the polymer during film preparation. The extractant extracts the pore-forming agent from the film to form pores.

[0095] Heat resistance can be tested and evaluated using existing testing methods. For example, it can be tested as follows: cut the microporous membrane into a 297mm×210mm sample, draw a 100mm×100mm outline in the middle, place it between 22 sheets of A4 paper (11 sheets on the top and 11 on the bottom), and then place it on a stainless steel wire mesh rack in the middle of a 150℃ constant temperature oven for 1 hour. After baking, remove it and let it cool to room temperature (25℃), measure the side length of the outline, and take the average value L. The heat shrinkage rate is calculated as (100-L) / 100×100%.

[0096] In some embodiments, the breathable fabric may be, but is not limited to, clothing fabric.

[0097] In some embodiments, the hydrophilic-lipophilic balance (HLB) value of the first ionic liquid is <10, and can be selected as 0 to 9.8. For example, the HLB value of the first ionic liquid can be, but is not limited to, any value or a range between any two values ​​from 0, 1, 2, 3, 3.2, 3.5, 3.6, 3.8, 4, 4.1, 4.3, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.3, 5.6, 5.9, 6, 6.2, 6.6, 6.8, 7, 7.3, 8, 8.2, 8.4, 8.9, 9, 9.5, 9.8. A hydrophilic-lipophilic balance value within the above range indicates good lipophilicity, enabling better binding with polymers in the microporous membrane.

[0098] Optionally, the hydrophilic-lipophilic balance value of the first ionic liquid is 3 to 7. Therefore, when applied to clothing fabrics, controlling the HLB value within a certain range can further reduce the oil absorption of the fabric and improve its performance, thereby reducing the cleaning frequency. The oil absorption can be evaluated, for example, by dropping 2 μL of paraffin oil (40°C, viscosity 45±5 cp) onto a 10 cm × 10 cm film surface and observing the diffusion area for 5 minutes; a larger diffusion area indicates higher oil absorption. The HLB value of the ionic liquid in this application can be determined and calculated using emulsification methods, critical micelle concentration, etc., but this application is not limited to these methods. Specifically, for example, turpentine oil (required HLB=16) and cottonseed oil (required HLB=6) can be mixed in a certain proportion to prepare an oil phase (covering the HLB range of 3 to 18); take 15g of oil phase + 5g of the sample to be tested + 80g of water, homogenize and emulsify (1500rpm, 5 minutes), let stand for 24 hours and observe the layering. The HLB value of the oil phase corresponding to the sample with the best stability is the HLB value of the sample to be tested; or, for example, use an HLB value measuring instrument (HLB-Master 3000) to measure it.

[0099] In some embodiments, the molecular weight of the first ionic liquid is 200 to 1000. For example, the molecular weight of the first ionic liquid can be, but is not limited to, any value or a range between any two of 200, 300, 400, 500, 600, 700, 800, 900, and 1000. The molecular weight of the ionic liquid can be determined directly by mass spectrometry. Specifically, the sample is ionized using techniques such as electrospray ionization (ESI) or matrix-assisted laser desorption / ionization (MALDI), and the molecular ion peak of the ionic liquid is found by obtaining the mass spectrum of the sample using a mass spectrometer. The molecular weight is then obtained based on the mass-to-charge ratio of the molecular ion peak. Of course, nuclear magnetic resonance (NMR), light scattering, and other methods can also be used for testing; this application is not limited to these methods.

[0100] The molecular weight of the first ionic liquid meets the above-mentioned range, which is beneficial to further improve the pore size uniformity and mechanical strength of the microporous membrane. At the same time, when the microporous membrane is applied to the field of clothing fabrics, it is beneficial to further improve the softness and processability of the fabric. Softness can be reflected by characterizing its stiffness. According to GB / T 41567, the measurement is carried out. Specifically, the groove width is 10.0 mm. The microporous membrane is placed on the sample stage and the groove is covered. 1 / 3 of the microporous membrane is in front of the groove and 2 / 3 is behind the groove. The test head is used to press the microporous membrane into the groove to complete one test and return to the initial position. The maximum force required for this process is used to characterize the stiffness of the microporous membrane.

[0101] In some embodiments, the boiling point of the first ionic liquid is 200℃ to 500℃. Specifically, the boiling point of the first ionic liquid may be, but is not limited to, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 275℃, 280℃, 285℃, 290℃, 295℃, 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, 500℃, or a range of any two of these values. The boiling point can be determined by conventional testing methods, including but not limited to distillation, and can be obtained by referring to the standard GB / T 616-2006.

[0102] The first ionic liquid has a suitable boiling point, which further enhances the mechanical strength of the microporous membrane while ensuring that the microporous membrane has a good pore structure.

[0103] In some embodiments, the viscosity of the first ionic liquid at 25°C is 20 cp to 100 cp. The viscosity can be determined using existing viscosity testing methods, such as placing a sample treated in a constant-temperature water bath at 25°C for 1 hour into a rotational viscometer and taking the viscosity reading. Specifically, the viscosity of the first ionic liquid can be any value or a range between any two values ​​from 20 cp, 30 cp, 40 cp, 50 cp, 60 cp, 70 cp, 80 cp, 90 cp, to 100 cp.

[0104] The aforementioned first ionic liquid has a suitable viscosity and good fluidity at room temperature, which helps to further improve the pore uniformity of the microporous membrane while also ensuring good thickness consistency. Therefore, when applied to the field of clothing fabrics, it can enable the fabric to have both good air permeability and moisture permeability and suitable oil absorption properties, thereby improving the performance of the fabric.

[0105] In some embodiments, the first ionic liquid is selected from one or more of ionic liquids such as imidazole salts, pyridine salts, quaternary ammonium salts, quaternary phosphonium salts, and pyrrolidines.

[0106] Specifically, the first ionic liquid is selected from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methyl sulfate, 1,3-dimethylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium tetrafluoroborate, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium trifluoromethanesulfonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium perchlorate, 1,3-dimethylimidazolium nitrate ... One or more of the following: imidazole methanesulfonate, 1,3-dimethylimidazolium p-toluenesulfonate, 1,3-dimethylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluoroantimonate.

[0107] In some embodiments, the first ionic liquid comprises one or more of the following: 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluoroantimonate.

[0108] In some embodiments, the second ionic liquid comprises one or more of the following: methyl 1,3-dimethylimidazolium sulfate, dimethyl 1,3-dimethylimidazolium phosphate, tetrafluoroborate, trifluoromethanesulfonate, perchlorate, nitrate, trifluoroacetate, ethyl-3-methylimidazolium bromide, iodide, ethyl 1-ethyl-3-methylimidazolium sulfate, methyl 1-ethyl-3-methylimidazolium sulfate, and dimethyl 1-ethyl-3-methylimidazolium phosphate.

[0109] It is understood that the above only lists some commonly used types of ionic liquids, but it is not limited to these. Other ionic liquids can also be used, as long as they meet the above conditions. They will not be listed exhaustively here.

[0110] In some embodiments, the mass percentage of the first ionic liquid in the microporous membrane is 0.01% to 6%. For example, the mass percentage of the first ionic liquid may be, but is not limited to, 0.01%, 0.02%, 0.05%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4%, 0.42%, 0.45%, 0.48%, 0.5%, 0.6%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, or a range of any two of these values. In some embodiments, the mass percentage of the first ionic liquid in the microporous membrane is 0.1% to 5%. Furthermore, in some embodiments, the mass percentage of the first ionic liquid in the microporous membrane is 0.1% to 0.5%. By controlling the content of the first ionic liquid, the permeability of the microporous membrane can be further improved.

[0111] In some embodiments, the microporous membrane comprises homopolymers or copolymers of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and norbornene, thermoplastic polyurethane elastomers (TPU), polyolefin elastomers (POE), polyethylene terephthalate (PET), polyurethane (PU), or mixtures of polymers thereof.

[0112] In some embodiments, the microporous membrane comprises a polyolefin. For example, the microporous membrane comprises a homopolymer or copolymer of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and norbornene.

[0113] In some embodiments, the microporous membrane includes one or more of polyethylene, polypropylene, and ethylene-propylene copolymer.

[0114] When applied to the field of apparel fabrics, in some embodiments, the viscosity-average molecular weight of the microporous membrane is 100,000 to 900,000, which is beneficial for further improving the softness and processability of the fabric. Softness can be characterized by its stiffness, measured according to GB / T 41567. Specifically, the slot width is 10.0 mm. The microporous membrane is placed on the sample stage and the slot is covered, with 1 / 3 of the microporous membrane in front of the slot and 2 / 3 behind. The test head is used to press the microporous membrane into the slot, completing one test, and then returning to the initial position. The maximum force required in this process characterizes the stiffness of the microporous membrane. The viscosity-average molecular weight of the polymer can be determined using conventional methods, including but not limited to determining the intrinsic viscosity at 135°C using decahydronaphthalene as a solvent according to GB1841-1980. This intrinsic viscosity is then substituted into the following (Formula 1) to calculate the viscosity-average molecular weight: Viscosity-average molecular weight (Mv) = (5.34 × 10⁻⁶) / ( ... 4 )×[η] 1.49 (Formula 1).

[0115] Specifically, the viscosity-average molecular weight of the microporous membrane can be, but is not limited to, any value or a range between any two of 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, and 900,000. In some embodiments, the viscosity-average molecular weight of the microporous membrane is 1,000,000 to 900,000.

[0116] In some embodiments, the microporous membrane further contains a second ionic liquid, which is an ionic salt that is liquid below 50°C. The hydrophilic-lipophilic balance (HLP) value of the second ionic liquid is greater than that of the first ionic liquid. This indicates that the second ionic liquid is more hydrophilic than the first ionic liquid, and the first ionic liquid is more lipophilic than the second ionic liquid. When applied to the field of apparel fabrics, it can further improve the fabric's breathability and moisture permeability, as well as its suitable oil absorption properties, thereby further enhancing the fabric's performance.

[0117] In some embodiments, the difference between the hydrophilic-lipophilic balance value of the second ionic liquid and the hydrophilic-lipophilic balance value of the first ionic liquid is <10, and can be selected as 1 to 9. For example, the difference between the hydrophilic-lipophilic balance value of the second ionic liquid and the hydrophilic-lipophilic balance value of the first ionic liquid can be, but is not limited to, 9, 8, 7, 6, 5, 4, 3, 2, 1, or any combination of these values. Specifically, the hydrophilic-lipophilic value of the second ionic liquid is 10 to 20. For example, the hydrophilic-lipophilic balance value of the second ionic liquid can be, but is not limited to, any value of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any combination of these values. The hydrophilic-lipophilic balance of the second ionic liquid is controlled within a certain range, which is beneficial to further improve the air permeability of the microporous membrane. When applied to the field of clothing fabrics, it is beneficial to further improve the moisture permeability and body comfort of the microporous membrane. The moisture permeability can be tested by referring to the positive cup method of GB / T 12704.1.

[0118] Specifically, the hydrophilicity and lipophilicity of the second ionic liquid can also be determined by emulsification testing. For example, an oil phase can be prepared by mixing polyoxyethylene (required HLB=20) and cottonseed oil (required HLB=6) in a certain proportion; take 15g of oil phase + 5g of the sample to be tested + 80g of water, homogenize and emulsify (1500rpm, 5 minutes), let it stand for 24 hours and observe the layering. The HLB value of the oil phase corresponding to the sample with the best stability is the HLB value of the sample to be tested; or, for example, it can be measured using an HLB value measuring instrument (HLB-Master 3000).

[0119] In some embodiments, the molecular weight of the second ionic liquid is smaller than that of the first ionic liquid. The second ionic liquid, being smaller than the first ionic liquid, has better hydrophilicity. Therefore, controlling the molecular weight of the second ionic liquid to be smaller than that of the first ionic liquid is beneficial for synergistically improving the air permeability of the microporous membrane. When applied to the field of clothing fabrics, this is beneficial for further improving the moisture permeability and comfort of the microporous membrane. The moisture permeability can be tested using the positive cup method in GB / T 12704.1.

[0120] In some embodiments, the molecular weight of the second ionic liquid is 100–250. For example, the molecular weight of the second ionic liquid can be, but is not limited to, any value of 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, or a range of any two of these values. Controlling the molecular weight of the second ionic liquid within a certain range is beneficial for further improving the air permeability of the microporous membrane. When applied to the field of clothing fabrics, it is beneficial for further improving the moisture permeability and comfort of the fabric. The moisture permeability can be tested using the positive cup method of GB / T 12704.1 for the moisture permeability of the microporous membrane.

[0121] In some embodiments, the boiling point of the second ionic liquid is 100°C to 500°C. For example, the boiling point of the second ionic liquid may be, but is not limited to, any value of 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 320°C, 340°C, 350°C, 360°C, 380°C, 400°C, 420°C, 440°C, 450°C, 460°C, 480°C, or 500°C, or a range of any two of these values. The above setup helps to further improve the air permeability of the microporous membrane, thereby further improving the moisture permeability of the clothing fabric.

[0122] In some embodiments, the viscosity of the second ionic liquid at 25°C is 10 cp to 50 cp. For example, the viscosity of the second ionic liquid can be any value or a range between any two values ​​from 10 cp, 12 cp, 15 cp, 18 cp, 20 cp, 22 cp, 25 cp, 28 cp, 30 cp, 32 cp, 35 cp, 38 cp, 40 cp, 42 cp, 45 cp, 48 cp, to 50 cp. Adopting the above configuration is beneficial for further improving the air permeability of the microporous membrane, thereby further improving the moisture permeability of the clothing fabric.

[0123] In some embodiments, the viscosity of the second ionic liquid at 25°C is 5 to 20 cp lower than that of the first ionic liquid at 25°C. Specifically, the viscosity of the second ionic liquid at 25°C can be any value or a range between any two values ​​that are lower than the viscosity of the first ionic liquid at 25°C by 5, 7, 9, 11, 13, 15, 17, 19, or 20 cp. By controlling the viscosity difference between the second and first ionic liquids, it is beneficial to further improve the pore size uniformity of the microporous membrane and better control its porosity, thereby further improving the moisture permeability of the clothing fabric.

[0124] In some embodiments, the mass percentage of the second ionic liquid in the microporous membrane is 0.01% to 3%. For example, the mass percentage of the second ionic liquid can be, but is not limited to, any value or a range of any two of the following: 0.01%, 0.02%, 0.05%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4%, 0.42%, 0.45%, 0.48%, 0.5%, 0.6%, 0.8%, 1%, 1.5%, 2%, 2.5%, and 3%. In this case, the mass percentage of the first ionic liquid in the microporous membrane is 0.01% to 5%, optionally 0.1% to 5%, and more preferably 0.1% to 0.5%.

[0125] In some embodiments, the mass percentage of the second ionic liquid in the microporous membrane is 0.1% to 0.5%. Controlling the mass percentage of the second ionic liquid within a certain range is beneficial for further improving the breathability of the product. Therefore, when applied to the field of clothing fabrics, it is beneficial for further improving the moisture permeability and comfort of the fabric. The moisture permeability can be tested for the moisture permeability of the microporous membrane using the positive cup method in GB / T 12704.1.

[0126] It is understood that the mass percentage of the second ionic liquid in this application can be tested by the following method: Weigh a 10cm × 10cm microporous membrane sample (M1), place the sample in 100mL of DCM solvent, sonicate at 100Hz for 15min, dry at 80℃ for 5min, weigh again (M2), and calculate using the following formula:

[0127] In some embodiments, the second ionic liquid is selected from one or more of ionic liquids such as imidazole salts, pyridine salts, quaternary ammonium salts, quaternary phosphonium salts, and pyrrolidines.

[0128] Specifically, the second ionic liquid is selected from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methyl sulfate, 1,3-dimethylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium tetrafluoroborate, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium trifluoromethanesulfonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium perchlorate, 1,3-dimethylimidazolium nitrate ... One or more of the following: imidazole methanesulfonate, 1,3-dimethylimidazolium p-toluenesulfonate, 1,3-dimethylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluoroantimonate.

[0129] It is understood that the above only lists some commonly used types of ionic liquids, but it is not limited to these. Other ionic liquids can also be used, as long as they meet the above conditions. They will not be listed exhaustively here.

[0130] It is understood that the second ionic liquid and the first ionic liquid can be of the same type, as long as they meet at least one of the above-defined ranges for HLB value, molecular weight, boiling point, and viscosity at 25°C. For example, the HLB value can be controlled by changing the structure of the anion and cation, such as by changing the alkyl chain length of the cation or introducing different functional groups, or by adding some high-boiling solvents, such as high-boiling ethers (ether solvents with a boiling point ≥300°C, specifically including one or more of ethylene glycol phenyl ether and propylene glycol phenyl ether).

[0131] In some embodiments, the microporous membrane further contains additives, including one or more of known additives such as antioxidants, metal soaps, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments. Metal soaps refer to metal salts formed by the reaction of metals other than alkali metals, metal oxides, or salts with fatty acids, rosin acids, naphthenic acids, etc., such as, but not limited to, calcium stearate and zinc stearate.

[0132] In some embodiments, the additive mass accounts for 0.01% to 5% of the total mass of the microporous membrane.

[0133] In some embodiments, the mass percentage of the additive in the microporous membrane is 0.1% to 1% of the total mass of the microporous membrane. For example, the mass percentage of the additive in the total mass of the microporous membrane may be, but is not limited to, 0.01%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range of these values. By controlling the mass percentage of the additive, it is beneficial to ensure the film-forming properties and quality of the microporous membrane while achieving the desired effects from the additive.

[0134] It is understood that this application does not impose any particular limitation on the way the additive is added to the microporous membrane. For example, it can be added by mixing with the main film-forming material of the microporous membrane during the preparation of the microporous membrane, or by immersing the intermediate membrane in a solution containing the additive at a certain stage of the preparation of the microporous membrane, or by coating the microporous membrane, etc.

[0135] In some embodiments, the microporous membrane comprises multiple layers of submembranes stacked together, wherein adjacent submembranes contain different polymers and all contain a first ionic liquid. It is understood that the difference in polymers between adjacent submembranes can be due to different types of polymers or different viscosity-average molecular weights of the polymers. It is also understood that the first ionic liquid in each submembrane may be the same or different.

[0136] This application does not specifically limit the average pore size of the microporous membrane. However, based on considerations of mechanical strength and windproof properties of clothing fabrics, in some embodiments, the average pore size of the microporous membrane is 20nm to 200nm. For example, the average pore size of the microporous membrane can be any value or a range between any two values ​​between 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, 155nm, 160nm, 165nm, 170nm, 175nm, 180nm, 185nm, 190nm, 195nm, and 200nm.

[0137] In some embodiments, the average pore size of the microporous membrane is 60 nm to 200 nm. The average pore size of the microporous membrane can be measured using a capillary porosity meter, for example, using a PMI instrument (Chia Yun Co., Ltd., CFP-1500AE model) with Galwick immersion solution (surface tension of 15.9 dynes / cm at 25°C) at 25°C. The pore size is expressed in nm. Of course, other conventional testing methods in the industry can also be used for testing.

[0138] This application does not specifically limit the mechanical strength of the microporous membrane. However, considering heat resistance and processability, in some embodiments, the transverse tensile strength (TD strength) of the microporous membrane is 500 kgf / cm². 2 ~5000 kgf / cm 2 For example, the TD strength of a microporous membrane can be, but is not limited to, 500 kgf / cm². 2 1000kgf / cm 2 1500kgf / cm 2 2000 kgf / cm 2 2500kgf / cm 2 3000 kgf / cm 2 3500kgf / cm 2 4000 kgf / cm 2 4500kgf / cm 2 5000 kgf / cm 2 Or a range consisting of any two of these values. Optionally, the transverse tensile strength (TD strength) of the microporous membrane is 500 kgf / cm. 2 ~3000kgf / cm 2 Furthermore, the transverse tensile strength (TD strength) of the microporous membrane is 700 kgf / cm². 2 ~1000kgf / cm 2 The transverse tensile strength (TD strength) of the microporous membrane is within the above range, which can further balance comfort and softness with reduced cracking.

[0139] In some embodiments, the longitudinal tensile strength (MD strength) of the microporous membrane is 1000 kgf / cm². 2 ~5000 kgf / cm 2 For example, the molecular weight density (MD) of a microporous membrane can be, but is not limited to, 1000 kgf / cm². 2 1500kgf / cm 2 2000 kgf / cm 2 2500kgf / cm 2 3000 kgf / cm 2 3500kgf / cm2 4000 kgf / cm 2 4500kgf / cm 2 5000 kgf / cm 2 Or a range consisting of any two of these values. Optionally, the longitudinal tensile strength (MD strength) of the microporous membrane is 1000 kgf / cm. 2 ~3000kgf / cm 2 .

[0140] In some embodiments, the puncture strength of the microporous membrane is 150 gf to 1000 gf. For example, the puncture strength of the microporous membrane may be, but is not limited to, 150 gf, 200 gf, 250 gf, 300 gf, 350 gf, 400 gf, 450 gf, 500 gf, 550 gf, 600 gf, 650 gf, 700 gf, 750 gf, 800 gf, 850 gf, 900 gf, 950 gf, 1000 gf, or a range of any two of these values. Optionally, the puncture strength of the microporous membrane is 150 gf to 400 gf.

[0141] This invention does not specifically limit the porosity of the microporous membrane. However, considering mechanical strength and the moisture permeability of the clothing fabric, in some embodiments, the porosity of the microporous membrane is 10% to 90%. For example, the porosity of the microporous membrane can be, but is not limited to, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or any combination of these values. In some embodiments, the porosity of the microporous membrane is 60% to 90%. Further, in some embodiments, the porosity of the microporous membrane is 70% to 90%.

[0142] This application does not specifically limit the air permeability of the microporous membrane. However, based on considerations of mechanical strength and the moisture permeability of clothing fabrics, in some embodiments, the air permeability of the microporous membrane is 10 sec / 100cc to 60 sec / 100cc. For example, the air permeability of the microporous membrane may be, but is not limited to, 10 sec / 100cc, 20 sec / 100cc, 30 sec / 100cc, 40 sec / 100cc, 50 sec / 100cc, 60 sec / 100cc, or any range of two of these values.

[0143] This application does not specifically limit the thickness of the microporous membrane. However, considering mechanical strength and the need for thinner fabrics, in some embodiments, the thickness of the microporous membrane is between 2 μm and 120 μm. For example, the thickness of the microporous membrane can be, but is not limited to, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 8 μm, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, or any range of these values. It is understood that the thickness of the microporous membrane can be selected according to the specific application scenario. In some embodiments, the thickness of the microporous membrane is between 3 μm and 20 μm.

[0144] In some embodiments, the thermal shrinkage rate of the microporous membrane is 1% to 2%. For example, the thermal shrinkage rate of the microporous membrane may be, but is not limited to, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any combination of these values.

[0145] In some embodiments, the oil absorption rate of the microporous membrane is 45% to 60%. For example, the oil absorption rate of the microporous membrane may be, but is not limited to, 45%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or any combination of these values.

[0146] In some embodiments, the stiffness of the microporous membrane is 1 gf / cm to 10 gf / cm. For example, the stiffness of the microporous membrane may be, but is not limited to, 1 gf / cm, 2 gf / cm, 3 gf / cm, 4 gf / cm, 5 gf / cm, 6 gf / cm, 7 gf / cm, 8 gf / cm, 9 gf / cm, 10 gf / cm, or any range of two of these values. Optionally, the stiffness of the microporous membrane is 3 gf / cm to 7 gf / cm.

[0147] In some embodiments, the moisture permeability of the microporous membrane is 2000 (g / m³). 2 ,24h)~20000(g / m 2 (24h). For example, the moisture permeability of a microporous membrane can be, but is not limited to, 2000 (g / m³). 2 ,24h), 4000 (g / m 2 ,24h), 6000 (g / m 2 ,24h), 8000 (g / m 2 ,24h),10000 (g / m 2 ,24h),12000 (g / m 2 ,24h), 14000 (g / m 2 ,24h),16000 (g / m 2,24h), 18000 (g / m 2 ,24h), 20000 (g / m 2 The value can be 24h or any combination of these values. Optionally, the moisture permeability of the microporous membrane is 6000 g / m³. 2 ,24h)~14000(g / m 2 (24h).

[0148] It is understood that the tensile strength (including longitudinal and transverse tensile strength) in this application can refer to GB / T 36363-2018. When testing transverse tensile strength, a strip with a longitudinal width of 15 mm is cut and clamped at both ends of the fixture, and the tensile testing machine speed is set to 200 mm / min. When testing the longitudinal tensile strength of the microporous membrane, a strip with a transverse width of 15 mm is cut and tested, with other parameter settings consistent with the conditions for the transverse tensile strength test. Puncture strength can be tested according to GB / T 36363-2018. After flattening and clamping the microporous membrane sample, puncture it at a rate of 300 mm / min, and determine the puncture strength data. Furthermore, porosity, air permeability, and thickness can be tested according to GB / T 36363-2018. Of course, other test methods can also be used for the aforementioned test items.

[0149] Secondly, this application provides a method for preparing a microporous membrane for breathable fabrics, comprising the following steps:

[0150] A mixture comprising polymer and ionic liquid is mixed, extruded, and cooled to form an intermediate film.

[0151] The intermediate membrane was stretched, extracted, and heat-set to obtain a microporous membrane;

[0152] The ionic liquid in the microporous membrane is 0.01% to 6% by mass, the air permeability of the microporous membrane is 10 sec / 100cc to 60 sec / 100cc, the ionic liquid includes a first ionic liquid, and the hydrophilic-lipophilic balance value of the first ionic liquid is <10.

[0153] In some embodiments, the mass percentage of the ionic liquid in the microporous membrane is 0.1% to 5%. Specifically, the mass percentage of the ionic liquid in the microporous membrane can be any value or a range between any two values ​​from 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, to 5.0%. Controlling the mass percentage of ionic liquid in microporous membranes within a certain range helps improve the overall performance of microporous membranes in the application of breathable fabrics.

[0154] Extensive research has revealed that mixing ionic liquids with polymers, especially those containing a first ionic liquid, without the need for commonly used paraffin oils or white oils, achieves better compatibility with various polymers, making it applicable to a wider range of polymer systems, and resulting in microporous membranes with superior performance. Therefore, this application provides a novel method entirely different from traditional membrane fabrication systems, offering a new research direction and approach for wet processes and solving the limitation on the use of polymer systems in traditional processes.

[0155] In some embodiments, the hydrophilic-lipophilic balance (HLB) value of the first ionic liquid is <10, and can be selected as 0 to 9.8. For example, the HLB value of the first ionic liquid can be, but is not limited to, any value or a range between any two values ​​from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9.5, to 9.8. In some embodiments, the hydrophilic-lipophilic balance (HLB) value of the first ionic liquid is 3 to 7. The hydrophilic-lipophilic balance (HLB) value is used to characterize the hydrophilicity and lipophilicity of a substance. The smaller the HLB value, the stronger the lipophilicity, and vice versa. Generally, the HLB value of paraffin is 0, and the HLB value of polyethylene glycol is 20, which are used as standards. When the hydrophilic-lipophilic balance value of the first ionic liquid is within the above range, it has good lipophilicity and can have good high-temperature compatibility with polymers in microporous membranes, making the above preparation method applicable to more polymer systems. The HLB value of this application can be determined and calculated by emulsification method, critical micelle concentration, etc., and this application is not limited thereto.

[0156] In some embodiments, the molecular weight of the first ionic liquid is 200 to 1000. For example, the molecular weight of the first ionic liquid can be, but is not limited to, any value or a range between any two of 200, 300, 400, 500, 600, 700, 800, 900, and 1000. A suitable molecular weight of the first ionic liquid allows for good high-temperature compatibility with polymers, thus enabling its application in high-temperature preparation processes of more polymer systems and resulting in higher-quality microporous membranes. The molecular weight of the ionic liquid can be directly determined using mass spectrometry. Specifically, the sample is ionized using techniques such as electrospray ionization (ESI) or matrix-assisted laser desorption / ionization (MALDI), and the molecular ion peak of the ionic liquid is found by obtaining the mass spectrum of the sample using a mass spectrometer. The molecular weight is then obtained based on the mass-to-charge ratio of the molecular ion peak. Alternatively, nuclear magnetic resonance (NMR) or light scattering methods can also be used, and this application is not limited to these methods.

[0157] In some embodiments, the boiling point of the first ionic liquid is 200°C to 500°C. The higher boiling point of the first ionic liquid allows it to better form a homogeneous phase with the polymer at high temperatures, which further facilitates the formation of intermediate films with uniform thickness and better film-forming properties through blending and extrusion. This helps to form microporous films with superior overall performance, meeting the needs of different application scenarios. Specifically, the boiling point of the first ionic liquid may be, but is not limited to, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, 295℃, 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, 500℃, or a range of any two of these values. The boiling point can be determined by conventional testing methods, including but not limited to distillation.

[0158] In some embodiments, the viscosity of the first ionic liquid at 25°C is 20 cp to 100 cp. Specifically, the viscosity of the first ionic liquid can be any value or a range between any two values ​​from 20 cp, 30 cp, 40 cp, 50 cp, 60 cp, 70 cp, 80 cp, 90 cp, and 100 cp. The aforementioned first ionic liquid has a suitable viscosity at room temperature, good fluidity, which is beneficial for mixing with polymers and for better control of thickness, porosity, and pore size during the preparation process. The viscosity can be determined using conventional testing methods, including but not limited to reading the viscosity after placing the sample treated in a constant-temperature water bath at 25°C for 1 hour into a rotational viscometer.

[0159] In some embodiments, the first ionic liquid is selected from one or more of imidazole salts, pyridine salts, quaternary ammonium salts, quaternary phosphonium salts, and pyrrolidines. It is understood that the ionic liquid may also have functionalized groups, such as hydroxyl, carboxyl-functionalized ionic liquids, ether groups, ester groups, amino groups, cyano groups, etc.

[0160] Specifically, the first ionic liquid is selected from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methyl sulfate, 1,3-dimethylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium tetrafluoroborate, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium trifluoromethanesulfonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium perchlorate, 1,3-dimethylimidazolium nitrate ... One or more of the following: imidazole methanesulfonate, 1,3-dimethylimidazolium p-toluenesulfonate, 1,3-dimethylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluoroantimonate.

[0161] It is understood that the above only lists some commonly used types of ionic liquids, but it is not limited to these. Other ionic liquids can also be used, as long as they meet the above conditions. They will not be listed exhaustively here.

[0162] In some embodiments, the mixture comprising the polymer and the ionic liquid may further include a high-boiling-point ether solvent, for example, an ether solvent with a boiling point ≥300°C. Specifically, the ether solvent may be one or more of ethylene glycol phenyl ether and propylene glycol phenyl ether. Adding the aforementioned high-boiling-point ether solvent is beneficial for further improving the compatibility between the ionic liquid and the polymer.

[0163] In some embodiments, the mass ratio of polymer to ionic liquid is (5–60):(40–95). Specifically, the mass ratio of polymer to ionic liquid can be any value or a range between any two values ​​from 5:95, 7:93, 9:91, 11:89, 13:87, 15:85, 17:83, 19:81, 21:79, 23:77, 25:75, 27:73, 29:71, 31:69, 33:67, 35:65, 37:63, 39:61, 41:59, 43:57, 45:55, 47:53, 49:51, 51:49, 53:47, 55:45, 57:43, 59:41, to 60:40. Controlling the mass ratio of polymer to ionic liquid within a certain range helps to control melt flow during processing, improve the quality of intermediate films, and make the prepared microporous films have better overall performance such as pore formation consistency and mechanical strength.

[0164] Specifically, the ionic liquid accounts for 40% to 95% of the total mass of the ionic liquid and polymer, and the polymer accounts for 5% to 60% of the total mass of the ionic liquid and polymer. Optionally, the ionic liquid accounts for 65% to 80% of the total mass of the ionic liquid and polymer, and the polymer accounts for 20% to 35% of the total mass of the ionic liquid and polymer.

[0165] In some embodiments, the polymer is selected from homopolymers or copolymers of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and norbornene, thermoplastic polyurethane elastomers (TPU), polyolefin elastomers (POE), polyethylene terephthalate (PET), polyurethane (PU), or mixtures of polymers thereof. In some embodiments, the polymer is selected from polyolefins, for example, homopolymers or copolymers of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and norbornene. In some embodiments, the polymer is selected from one or more of polyethylene, polypropylene, and ethylene-propylene copolymers. The application of the first ionic liquid to microporous membranes expands the types of microporous membranes applicable not only to polyethylene (PE) systems but also to other polymer systems such as polypropylene (PP).

[0166] Researchers have creatively discovered that traditional wet-process microporous membrane preparation methods use liquid paraffin oil as a pore-forming agent. However, due to the poor compatibility of paraffin oil with different polymer melt systems, it can only effectively use polyethylene (PE) as the main raw material for microporous membranes, and cannot produce microporous membranes with other polymer raw material systems. This also limits further improvements in the performance of microporous membranes, hindering their application in various fields. Currently, some raw materials with melting points above 170℃ (such as PP) cannot be processed into a suitable melt in existing paraffin oil melt systems, making it difficult to produce microporous membranes, or only allowing for the production of microporous membranes with poor performance consistency (e.g., porosity, strength) through dry processes. This application, through extensive research, has found that using a first ionic liquid eliminates the need for traditional pore-forming agents such as liquid or solid paraffin oil, achieving better compatibility with a wider range of polymers, making it applicable to more polymer systems, and producing microporous membranes with superior performance.

[0167] In some embodiments, in the step of mixing and extruding a mixture comprising a polymer and an ionic liquid, the mixing of the polymer and the ionic liquid can be done in one step or in multiple steps.

[0168] It can be understood that a single mixing involves mixing all the components, including the polymer and the ionic liquid, at once, where the polymer and the ionic liquid can be one or more types. Multiple mixing involves mixing the polymer and ionic liquid in two or more separate batches, where the polymer and ionic liquid content is the same or different in each batch, and the types of polymer and ionic liquid can also be the same or different in each batch.

[0169] In some embodiments of this application, the multiple mixing steps can meet the needs of microporous membrane products for more diverse performance and more differentiated application scenarios.

[0170] When applied to the field of apparel fabrics, in some embodiments, the polymer has a viscosity-average molecular weight of 100,000 to 900,000, which is beneficial for balancing the softness and processability of the fabric.

[0171] Specifically, the viscosity-average molecular weight of the polymer can be any value or a range between any two of the following: 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, and 900,000. Controlling the viscosity-average molecular weight of the polymer within the range specified in this application helps to control melt flow during processing and improve the quality of intermediate films. The viscosity-average molecular weight of the polymer can be determined using conventional methods, including but not limited to determining the intrinsic viscosity at 135°C using decahydronaphthalene as a solvent according to GB1841-1980, and substituting this intrinsic viscosity into the following formula (Formula 1) to calculate the viscosity-average molecular weight: Viscosity-average molecular weight (Mv) = (5.34 × 10⁻⁶) / ( ... 4 )×[η] 1.49 (Formula 1).

[0172] It is understood that the methods for preparing microporous membranes in some embodiments of this application are also applicable to the preparation of microporous membranes with other molecular weights and other thicknesses.

[0173] Unlike traditional wet processes, this method uses ionic liquids mixed with polymers, which has less impact on polymer cooling and crystallization, results in more thorough phase separation, and allows for greater flexibility in adjusting the solid content during extrusion, leading to better melt quality. This makes it easier to adjust micropore size, porosity, and other parameters. For example, traditional wet and dry stretching techniques struggle to achieve porosities above 60% in microporous membranes, typically remaining at 20%–60%. In some embodiments of this application, the preparation method uses ionic liquids mixed with polymers without the addition of pore-forming agents such as paraffin oil, enabling the preparation of microporous membranes with higher porosities. For instance, the porosity of the microporous membrane can be adjusted between 10% and 90%, and further, between 60% and 90%. Traditional wet and dry stretching processes struggle to achieve an average pore size of over 60 nanometers for microporous membranes, typically ranging from 20 nm to 50 nm. Some embodiments of this application utilize preparation methods that can adjust the average pore size range of the microporous membrane between 20 nm and 200 nm to meet the performance requirements of different applications (e.g., mechanical strength and windproof properties of clothing fabrics). Furthermore, the average pore size of the microporous membrane can reach over 60 nm, for example, between 60 nm and 200 nm. For example, the average aperture can be any value or a range between any two values ​​between 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, 155nm, 160nm, 165nm, 170nm, 175nm, 180nm, 185nm, 190nm, 195nm, and 200nm. Furthermore, in some embodiments of this application, using an ionic liquid containing a first ionic liquid as a pore-forming agent can prepare microporous membranes with lower permeability, for example, permeability of 10 sec / 100cc to 60 sec / 100cc (the permeability of microporous membranes prepared by conventional wet and dry processes is 90 sec / 100cc to 500 sec / 100cc).

[0174] In some embodiments, during the step of mixing and extruding the polymer and ionic liquid, the mixing and extrusion temperature T 挤 For T 挤 =Polymer melting point T m +(15℃~60℃). In some embodiments, T 挤 =Polymer melting point T m +(15℃~45℃). Control the temperature of the mixed extrusion at the polymer melting point T. m+ (15℃~60℃) helps to reduce the risk of polymer degradation at excessively high temperatures while ensuring processability. At the same time, a lower extrusion temperature means that it is easier to reach the phase separation temperature. Therefore, the production efficiency is higher. Under the same conditions, the production line can be faster and more efficient. The final microporous membrane has better overall performance and meets the performance requirements of microporous membranes for different application scenarios.

[0175] Specifically, if the polymer is a polyolefin, its mixing and extrusion temperature can be from 145°C to 300°C. In some embodiments, the polymer is a polyolefin, and its mixing and extrusion temperature can be from 145°C to 200°C. For example, the mixing and extrusion temperature can be, but is not limited to, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, or any combination of these values. As mentioned earlier, traditional wet-process paraffin oil-polyethylene co-extrusion biaxial systems require extrusion temperatures set high above the polymer's melting point to increase fluidity. However, in some embodiments of this application, compared to traditional paraffin oil pore-forming agents, the extrusion temperature can be further reduced, resulting in higher fluidity at a relatively lower and suitable temperature, thus reducing the risk of polymer degradation due to increased temperature. For example, under the same conditions, the extrusion temperature can be reduced by 30–60°C, effectively reducing the risk of polymer oxidation or molecular weight degradation due to high temperatures. Furthermore, a lower extrusion temperature means it is easier to reach the phase separation temperature, resulting in higher production efficiency. Under the same conditions, the production line can achieve faster and more efficient production speeds.

[0176] In some embodiments, during the step of extruding the mixture comprising the polymer and the ionic liquid, the melt index of the polymer is 0.6 g / 10 min to 10 g / 10 min. In some embodiments, the melt index of the polymer is 1.3 g / 10 min to 6 g / 10 min. The test conditions for the melt index are as follows: polymers with a viscosity-average molecular weight below 1 million are tested at 190°C and 2.16 kg; polymers with a viscosity-average molecular weight above 1 million are tested at 190°C and 21.6 kg. The ionic liquid includes a first ionic liquid, which gives the blend system a suitable melt index, resulting in good high-temperature fluidity of the melt, thereby ensuring uniform mixing of the blend system, improving the quality of the intermediate film, and reducing processing difficulty. The polymer can also be selected from polymers with a melting point below 300°C, such as polyolefins, which can also form good interactions with the ionic liquid, further improving the processability of the microporous membrane.

[0177] In some embodiments, during the step of mixing and extruding the mixture comprising the polymer and the ionic liquid, additives may also be added. These additives include one or more known additives such as antioxidants, metal soaps like calcium stearate and zinc stearate, UV absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments. Adding additives can improve the properties of the microporous membrane, such as its antioxidant properties.

[0178] Specifically, the mass ratio of additive to polymer is 1:(20 to 10000). In some embodiments, the mass ratio of additive to polymer is 1:(100 to 1000). For example, the mass ratio of additive to polymer may be, but is not limited to, 1:20, 1:50, 1:80, 1:100, 1:150, 1:200, 1:250, 1:300, 1:350, 1:400, 1:450, 1:500, 1:550, 1:600, 1:650, 1:700, 1:750, 1:800, 1:850, 1:900, 1:950, 1:1000, 1:2000, 1:3000, 1:5000, 1:8000, 1:10000, or any range of two of these values. By controlling the mass ratio of additives to polymers, it is beneficial to ensure the film-forming properties and quality of microporous membranes while achieving the corresponding effects brought by additives.

[0179] It is understood that the additive is not limited to the step of mixing and extruding the mixture including the polymer and the ionic liquid. In other embodiments, the additive can also be added by immersing the intermediate membrane in a solution containing the additive at a certain stage of the preparation process of the microporous membrane, or by coating the microporous membrane. This application does not make any particular limitation.

[0180] Specifically, in some embodiments, the preparation method of some embodiments of this application may further include steps such as cooling and molding, stretching, extraction, and heat setting.

[0181] In some embodiments, during the cooling and forming step, the cooling method may be rapid roller contact cooling, or other cooling methods such as water cooling and air cooling, or a combination of two or more cooling methods, to cool and form the sheet. The cooling and forming temperature is 10℃ to 60℃. In some embodiments, the cooling and forming temperature is 10℃ to 30℃. For example, the cooling and forming temperature may be, but is not limited to, any value or a range of any two of the following: 10℃, 12℃, 14℃, 15℃, 16℃, 18℃, 20℃, 22℃, 24℃, 25℃, 26℃, 28℃, 30℃, 32℃, 34℃, 35℃, 36℃, 38℃, 40℃, 42℃, 44℃, 45℃, 46℃, 48℃, 50℃, 52℃, 54℃, 55℃, 56℃, 58℃, and 60℃. Controlling the cooling and molding temperature within the range specified in this application helps to achieve more thorough phase separation, improves the quality of the intermediate membrane, and can control the comprehensive properties of the final microporous membrane, such as pore size uniformity and mechanical strength, while also taking into account the economic efficiency of the process.

[0182] In some embodiments, the biaxial stretching process may involve first performing a longitudinal stretch with a stretch ratio of 3 to 19 times, followed by a transverse stretch with a stretch ratio of 5 to 19 times. In some embodiments, the longitudinal stretch ratio is 10 to 19 times. For example, the longitudinal stretch ratio may be, but is not limited to, any value from 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19 times, or a range of any two of these values. In some embodiments, the transverse stretch ratio is 10 to 19 times. For example, the transverse stretch ratio may be, but is not limited to, any value from 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19 times, or a range of any two of these values.

[0183] In other embodiments, the biaxial stretching process may also involve simultaneous transverse and longitudinal stretching, with a total stretching ratio, for example, ranging from 15 to 361 times. In some embodiments, the total stretching ratio is 100 to 361 times. For example, the total stretching ratio may be, but is not limited to, any value from 15, 30, 50, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, and 361 times, or a range consisting of any two of these values. It is understood that controlling the biaxial stretching ratio within the range of this application allows the intermediate film after cooling and molding to be oriented in each stretching direction, thereby facilitating the control of the microporous film to obtain suitable mechanical strength or stiffness, and thus meeting the usage requirements of different application scenarios.

[0184] In some embodiments, the extraction temperature is 15°C to 50°C. For example, the extraction temperature can be, but is not limited to, any value among 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, and 50°C, or a range of any two of these values. Using the above settings is beneficial for improving extraction efficiency, controlling the content of ionic liquid and extractant on the final microporous membrane, controlling the pore uniformity of the microporous membrane, and exhibiting suitable water permeability, moisture permeability, and oil absorption, thereby meeting the usage requirements of different application scenarios.

[0185] In some embodiments, the stretching ratio for transverse heat setting is 1 to 2 times, and the heat setting temperature is 90 to 300°C. In some embodiments, the heat setting temperature is 90 to 180°C, and further, the heat setting temperature can be 90 to 145°C. For example, the stretching ratio for transverse heat setting can be, but is not limited to, any value from 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 times, or a range of any two of these values. The heat-setting temperature can be, but is not limited to, any value or a range of any two of the following: 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, and 300℃. By controlling the stretching ratio and temperature of the transverse heat-setting within the range of this application, the crystallinity of the microporous membrane is further improved through the dual effects of heating and molecular orientation, thus solidifying the microporous structure of the membrane and helping to enhance its overall performance, thereby meeting the needs of different application scenarios.

[0186] In some embodiments, the extractant in the extraction step includes dichloromethane. Traditional paraffin oil / polyethylene co-extrusion biaxial stretching processes primarily use low-boiling-point solvents such as dichloromethane as extractants to remove pore-forming agents causing phase separation in the film. In some embodiments of this application, the pore-forming agent includes a first ionic liquid, and conventionally used dichloromethane extractants can also be used for extraction, following conventional extraction processes. The extracted extractant is then directly separated by distillation. During the drying process, the gaseous dichloromethane is adsorbed or compressed, and finally condensed and recovered for reuse.

[0187] In other embodiments, the extraction step uses a mixed solvent of a second ionic liquid and water as the extractant. The second ionic liquid has a higher hydrophilic-lipophilic balance (HLP) value than the first ionic liquid. This indicates that the second ionic liquid is more hydrophilic than the first, and the first ionic liquid is more lipophilic than the second, thus enabling the extraction of the first ionic liquid. The extracted film intermediate is then dried to remove water, yielding a microporous film.

[0188] In some embodiments, the difference between the hydrophilic-lipophilic balance value of the second ionic liquid and that of the first ionic liquid is <10. In some embodiments, the hydrophilic-lipophilic balance value of the second ionic liquid is 10–20. This configuration improves the moisture permeability of the microporous membrane when applied to clothing fabrics.

[0189] In some embodiments, the molecular weight of the second ionic liquid is smaller than that of the first ionic liquid. The smaller molecular weight of the second ionic liquid results in better hydrophilicity. Furthermore, the smaller molecular weight of the second ionic liquid is beneficial for improving the moisture permeability of microporous membranes when applied to clothing fabrics.

[0190] In some embodiments, the molecular weight of the second ionic liquid is between 100 and 250. For example, the molecular weight of the second ionic liquid can be, but is not limited to, any value or a range between any two of 100, 115, 130, 145, 160, 175, 190, 205, 220, 235, and 250. Controlling the molecular weight of the second ionic liquid within a certain range is beneficial for improving the moisture permeability of microporous membranes when applied to clothing fabrics.

[0191] In some embodiments, the boiling point of the second ionic liquid is 100°C to 500°C. Specifically, the boiling point of the second ionic liquid can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, etc. The temperature range is any value or any two values ​​from the following: ℃, 235℃, 240℃, 245℃, 250℃, 255℃, 275℃, 280℃, 285℃, 290℃, 295℃, 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, and 500℃. Using the above settings is beneficial for improving the moisture permeability of microporous membranes when applied to clothing fabrics.

[0192] In some embodiments, the viscosity of the second ionic liquid at 25°C is 10 cp to 50 cp. Specifically, the viscosity of the second ionic liquid at 25°C can be any value or a range between any two of the following: 10 cp, 12 cp, 14 cp, 16 cp, 18 cp, 20 cp, 22 cp, 24 cp, 26 cp, 28 cp, 30 cp, 32 cp, 34 cp, 36 cp, 38 cp, 40 cp, 42 cp, 44 cp, 46 cp, 48 cp, and 50 cp. This configuration is beneficial for improving the moisture permeability of microporous membranes when applied to clothing fabrics.

[0193] In some embodiments, the viscosity of the second ionic liquid at 25°C is 5 to 20 cp lower than that of the first ionic liquid at 25°C. Specifically, the viscosity of the second ionic liquid at 25°C can be any value or a range between any two values ​​that are lower than the viscosity of the first ionic liquid at 25°C by 5, 7, 9, 11, 13, 15, 17, 19, or 20 cp. This configuration improves extraction efficiency and helps control the ionic liquid content on the surface of the microporous membrane. Furthermore, the interaction between the two ionic liquids and the polymer results in a microporous membrane with excellent overall performance, meeting the needs of various applications.

[0194] In some embodiments, the second ionic liquid is selected from one or more of imidazole salts, pyridine salts, quaternary ammonium salts, quaternary phosphonium salts, pyrrolidines, and functionalized ionic liquids.

[0195] Specifically, the second ionic liquid is selected from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methyl sulfate, 1,3-dimethylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium tetrafluoroborate, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium trifluoromethanesulfonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium perchlorate, 1,3-dimethylimidazolium nitrate ... One or more of the following: imidazole methanesulfonate, 1,3-dimethylimidazolium p-toluenesulfonate, 1,3-dimethylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluoroantimonate.

[0196] It is understood that the above only lists some commonly used types of ionic liquids, but it is not limited to these. Other ionic liquids can also be used, as long as they meet the above conditions. They will not be listed exhaustively here.

[0197] In some embodiments, the mass percentage concentration of the second ionic liquid in the extractant is 5% to 10%. For example, the mass percentage concentration of the second ionic liquid in the extractant can be, but is not limited to, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or any combination of these values. Adopting the above configuration helps to improve the demulsification efficiency during the extraction process, resulting in higher extraction efficiency. Simultaneously, it reduces the use of low-boiling-point organic extractants, lowers the organic waste gas generated during production, making the production process more environmentally friendly. Furthermore, it allows for control of the ionic liquid content on the final microporous membrane, enabling the microporous membrane to possess superior overall performance.

[0198] In some embodiments, after the extraction step, the method further includes: washing the extracted microporous membrane intermediate with water, separating it with a reverse osmosis membrane, and drying it.

[0199] The ionic liquid in the microporous membrane intermediate is removed by washing with water, and the first ionic liquid, the second ionic liquid and water can be separated by reverse osmosis membrane separation, which facilitates subsequent recycling and reuse.

[0200] It should be noted that after extraction and before drying, other steps can be added as needed, such as washing, wetting, and cross-linking.

[0201] In some embodiments, a washing step is further included after extraction. The washing solution includes a second ionic liquid and a washing agent, the washing agent including water, and the second ionic liquid being the second ionic liquid of this application. The mass percentage concentration of the second ionic liquid in the washing solution is not higher than 10%. A concentration of the second ionic liquid not higher than 10% in the washing solution can effectively control the diffusion rate of the second ionic liquid extractant from the film into the washing solution, ensuring washing efficiency and washing quality.

[0202] In some embodiments, a multi-stage washing method can be used during the washing process, wherein the concentration of the second ionic liquid in the washing solution of each subsequent wash is no higher than 30 wt% of the concentration of the second ionic liquid in the washing solution of the previous wash. Controlling the concentration of the second ionic liquid in the washing solution to decrease sequentially can better control the washing efficiency. Furthermore, controlling the concentration of the second ionic liquid in the washing solution of each subsequent wash to be no higher than 30 wt% of the concentration of the second ionic liquid in the washing solution of the previous wash can better control the residual content of the ionic liquid in the membrane while maintaining high washing efficiency. Secondly, it can also better prevent the second ionic liquid extractant in the membrane from being washed too quickly, which could cause the microporous structure to collapse and affect the quality of the microporous membrane.

[0203] In some embodiments, a water washing step is included after extraction. The water washing includes a first-stage water washing and a second-stage water washing. The mass percentage concentration of the second ionic liquid in the water washing solution used in the first-stage water washing is 3% to 5%, and the mass percentage concentration of the second ionic liquid in the water washing solution used in the second-stage water washing is not higher than 1%, and the mass percentage concentration of the second ionic liquid in the water washing solution used in the second-stage water washing is not higher than 30 wt% of the mass percentage concentration of the second ionic liquid in the water washing solution used in the first-stage water washing.

[0204] In some embodiments, the washing process further includes a step of performing a second spraying with a second spray liquid, the second spray liquid comprising water.

[0205] Before drying the wet membrane, a wetting step may be included, where the type of wetting solution can be freely selected according to the desired purpose. For example, to better control the ionic liquid content of the microporous membrane, the wetting solution may include the ionic liquid of this application and water, with the mass percentage concentration of the ionic liquid in the wetting solution being 0.05% to 5%. For example, to achieve modification or crosslinking of the porous membrane, the wetting solution may include commonly used modifying agents, initiators, and crosslinking agents in the art. In some embodiments, a crosslinking step is performed after this wetting step to better achieve modification or crosslinking of the porous membrane. The mass percentage concentration of the ionic liquid in the wetting solution may be any value or a range between any two values ​​from 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, to 0.5%.

[0206] It is understood that the steps of cooling, forming, stretching, and heat setting can also be performed using existing methods in the art. For example, biaxial stretching can be performed separately in the transverse and longitudinal directions, or simultaneously in the transverse and longitudinal directions, which will not be elaborated here. In addition, the steps of cooling, forming, biaxial stretching, and heat setting can be performed using methods commonly used in the art, and can be carried out on the basis of existing wet process production lines, with high compatibility.

[0207] It is understood that after the heat setting step, there are also steps of winding and slitting, which can be done using existing methods in the field and will not be described in detail here.

[0208] In some embodiments of this application, since the pore-forming agent contains a first ionic liquid, an organic low-boiling-point solvent such as dichloromethane (DCM) can be selected for extraction and drying to remove the pore-forming agent. Alternatively, a suitable mixed solvent of a second ionic liquid and water can be selected, and a polar ionic liquid with demulsification efficiency can be added to the extraction environment. The pore-forming agent is then removed by washing with purified water. Because the drying portion of this extraction process contains only water, no organic waste gas is generated, making the production process more environmentally friendly. Furthermore, when adding additives such as antioxidants to the polymer and pore-forming agent blend system, using a mixed solvent of the second ionic liquid and water as the extractant is beneficial because the extractant has good hydrophilicity and is less likely to extract oil-soluble additives, allowing the additives to remain in the microporous membrane, which improves the performance of the microporous membrane.

[0209] Please refer to Figures 1 and 2. Figure 1 is a scanning electron microscope (SEM) image of a polyethylene microporous membrane prepared by a conventional process (magnification of 20Kx); Figure 2 is a scanning electron microscope (SEM) image of a polyethylene microporous membrane from some embodiments of this application (magnification of 20Kx).

[0210] As can be seen from the figures above, the microporous membrane prepared using this application has a better pore structure than that obtained by traditional processes, which is more conducive to air permeability, moisture permeability, and oil absorption. Scanning electron micrographs of the microporous membrane can be obtained according to the methods specified in industry standard JY / T 0584-2020 "General Rules for Analysis Methods of Scanning Electron Microscopy".

[0211] Thirdly, this application provides a breathable fabric, which includes the microporous membrane described in the first aspect or the microporous membrane prepared by the preparation method described in the second aspect.

[0212] Specifically, the breathable fabric includes a first surface layer and a microporous membrane located on the first surface layer. The first surface layer is the outermost material layer of the breathable fabric, which is in direct contact with the outside world and can showcase the fabric's appearance, color, pattern, and texture.

[0213] In some embodiments, the breathable fabric further includes a second outer layer disposed on the other side of the microporous membrane. The second outer layer is the innermost layer of the breathable fabric, typically close to the skin, and serves to support and complement the fabric layers.

[0214] In some embodiments, the microporous membrane can be bonded and fixed to the first and second surface layers by dry pressing with hot melt adhesive.

[0215] In some embodiments, a functional coating may also be included between the microporous membrane and the second surface layer.

[0216] In some embodiments, the functional coating may be formed by compounding with functional materials commonly used in the art, such as polyurethane, according to functional requirements.

[0217] In some embodiments, the functional coating and the fabric are bonded and fixed together by dry lamination with hot melt adhesive. In some embodiments, the breathable fabric may be, but is not limited to, clothing fabric.

[0218] To make the objectives and advantages of this application clearer, the microporous membrane and its effects of this application are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and should not be used to limit this application. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods in the embodiments that do not specify specific conditions are implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0219] Example 1

[0220] This embodiment provides a microporous membrane comprising a polymer and an ionic liquid. The ionic liquid includes a first ionic liquid and a second ionic liquid, with the first ionic liquid and the second ionic liquid comprising 0.1% and 0.15% by mass, respectively, in the microporous membrane. The polymer is polyethylene with a viscosity-average molecular weight of 600,000, a melt index of 1.6 g / 10 min, and a melting point of 139 °C. The first ionic liquid comprises 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, and a Lewis acid in a mass ratio of 35:35:10:10:9:1, with an HLB value of 6, a molecular weight of 269, a boiling point of 260°C, and a viscosity of 17.3 cp at 25°C. The second ionic liquid comprises 1,3-dimethylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium dimethyl phosphate, and 1-ethyl-3-methylimidazolium trifluoroacetate in a mass ratio of 45:33:12:10, with an HLB value of 13, a molecular weight of 260, a boiling point of 230°C, and a viscosity of 11 cp at 25°C. Specific parameters are shown in Tables 1 to 3.

[0221] The method for preparing the microporous membrane in this embodiment includes the following steps:

[0222] (1) The mixture comprising the polymer and the first ionic liquid is mixed and extruded at an extrusion temperature of 180°C and cooled and shaped at 20°C to obtain an intermediate film; the mass ratio of the polymer to the first ionic liquid is 25:75.

[0223] (2) The intermediate membrane is first stretched longitudinally by a ratio of 3.5, and then stretched transversely by a ratio of 9 to obtain the stretched intermediate membrane.

[0224] (3) The stretched intermediate membrane was extracted at 25°C. The extractant consisted of a second ionic liquid and water. The mass percentage concentration of the second ionic liquid in the extractant was 10%. The second ionic liquid in the extractant consisted of 1,3-dimethylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium dimethyl phosphate, and 1,3-dimethylimidazolium nitrate in a mass ratio of 45:33:12:10. After extraction, the membrane was washed with water, separated by reverse osmosis membrane, and dried. The washing solution consisted of the second ionic liquid and water, and a two-stage washing method was adopted. The mass percentage concentration of the second ionic liquid in the first stage of water washing was 4%, and the mass percentage concentration of the second ionic liquid in the second stage of water washing was 0.3%.

[0225] (4) The intermediate membrane after extraction and drying was heat-set to obtain a microporous membrane. The stretching ratio of the transverse heat-setting was 1.7 times, and the heat-setting temperature was 120℃.

[0226] Some of the process parameters in the above preparation process are shown in Table 3.

[0227] Examples 2-5

[0228] The microporous membranes of Examples 2-5 are similar to those of Example 1, except that the mass percentage of the first ionic liquid in the microporous membranes is different.

[0229] The preparation methods of the microporous membranes in Examples 2-5 are similar to those in Example 1, except that the mass ratio of the polymer to the first ionic liquid is different, and the mass percentage concentration of the second ionic liquid in the extractant is different. Specific parameters are shown in the table below. Other parameters are the same as in Example 1 and will not be repeated.

[0230] Examples 6-9

[0231] The microporous membranes in Examples 6-9 are similar to those in Example 1, except that the ionic liquid compositions are different. Details are shown in the table below.

[0232] The preparation methods of the microporous membranes in Examples 6-9 are the same as those in Example 1, and will not be repeated here.

[0233] Example 10

[0234] The microporous membrane of Example 10 is similar to that of Example 1, except that it is a multilayer co-extruded membrane. The first layer is the same as that of the microporous membrane in Example 1. In the second layer, the polymer is polypropylene with a viscosity-average molecular weight of 500,000, a melt index of 1.8 g / 10 min, a melting point of 172 °C, and an extrusion temperature of 210 °C. The first and second ionic liquids in the first and second layers are the same, respectively. See Tables 1 to 3 for details.

[0235] The preparation steps of the microporous membrane in this embodiment are the same as those in Example 1, and will not be repeated here.

[0236] Example 11

[0237] The microporous membrane in this embodiment is similar to that in Embodiment 1, except that the microporous membrane does not contain a second ionic liquid.

[0238] The preparation method of the microporous membrane in this embodiment is similar to that in Example 1, except that the extractant used in the extraction process is dichloromethane. Other parameters are the same as in Example 1 and will not be repeated.

[0239] Examples 12 to 14

[0240] The microporous membranes of Examples 12 to 14 are similar to those of Example 1, except that the mass percentage of the second ionic liquid is different.

[0241] The preparation methods of the microporous membranes in Examples 12-14 are similar to those in Example 1, except that the mass percentage concentration of the second ionic liquid differs during the second-stage water washing process. Details are shown in Tables 2 and 3. Other parameters are the same as in Example 1 and will not be repeated.

[0242] Example 15

[0243] The microporous membrane in this embodiment is similar to that in Example 1, except that the polymer is different. In this embodiment, the polymer is polyolefin elastomer POE with a viscosity-average molecular weight of 300,000, a melt index of 3.3 g / 10 min, and a melting point of 116 °C.

[0244] The preparation method of the microporous membrane in this embodiment is similar to that in Example 1, except that the extrusion temperature, cooling and molding temperature, and heat setting process are different. In this embodiment, the extrusion temperature is 168°C, the cooling and molding temperature is 25°C, the stretching ratio for transverse heat setting is 1.3 times, and the heat setting temperature is 110°C. Details are shown in Table 3 below. Other parameters are the same as in Example 1 and will not be repeated.

[0245] Comparative Example 1

[0246] Comparative Example 1 provides a microporous membrane similar to Example 1, except that it does not contain ionic liquid, uses paraffin oil as a pore-forming agent, and dichloromethane as an extractant.

[0247] The preparation steps of the microporous membrane in Comparative Example 1 are similar to those in Example 1, except that steps (1) and (3) are different. Steps (1) and (3) of Comparative Example 1 are as follows:

[0248] (1) The mixture including polymer and paraffin oil is mixed and extruded at an extrusion temperature of 180°C and cooled and shaped at 20°C to obtain an intermediate film; the mass ratio of polymer to paraffin oil is 25:75.

[0249] (3) Extract the stretched intermediate membrane at a temperature of 25°C using dichloromethane as the extractant, and then dry it.

[0250] Comparative Example 2

[0251] Comparative Example 2 provides a microporous membrane similar to the microporous membrane of Example 1, except that the mass percentage of the ionic liquid is different. In Comparative Example 2, the mass percentages of the first ionic liquid and the second ionic liquid in the microporous membrane are 5.5% and 1%, respectively, and the total mass percentage of the ionic liquid is 6.5%. See Tables 1 to 3 for details.

[0252] The preparation method of the microporous membrane in Comparative Example 2 is similar to that in Example 1, except that the mass percentage concentration of the second ionic liquid in the extractant and the mass percentage concentration of the second ionic liquid in the second-stage water wash are different. Details are shown in the table below.

[0253] Comparative Example 3

[0254] Comparative Example 3 provides a microporous membrane similar to the microporous membrane of Example 1, except that the mass percentage of the ionic liquid is 0.15%, and it contains only the second ionic liquid and not the first ionic liquid. Everything else is the same as in Example 1 and will not be repeated.

[0255] The preparation method of the microporous membrane in Comparative Example 3 is similar to that in Example 1, except that step (1) is different. In step (1) of Comparative Example 2, the first ionic liquid in Example 1 is replaced with an equal mass of paraffin oil. The other steps are the same as in Example 1 and will not be repeated.

[0256] Comparative Example 4

[0257] Comparative Example 4 provides a microporous membrane similar to that of Example 15, except that the mass percentage of the ionic liquid is different. In Comparative Example 4, the mass percentages of the first and second ionic liquids in the microporous membrane are 5.5% and 1%, respectively, and the total mass percentage of the ionic liquid is 6.5%. See Tables 1 to 3 for details.

[0258] The preparation method of the microporous membrane in Comparative Example 4 is similar to that in Example 15, except that the mass percentage concentration of the second ionic liquid in the extractant and the mass percentage concentration of the second ionic liquid in the second-stage water wash are different. Details are shown in the table below.

[0259] Table 1

[0260] Table 2

[0261] Table 3

[0262] The microporous membranes prepared in the above embodiments and comparative examples were characterized, and the results are shown in Table 4 below. Porosity, air permeability, and thickness were tested according to GB / T 36363-2018. Tensile strength (including longitudinal tensile strength and transverse tensile strength) was tested according to GB / T 36363-2018. When testing transverse tensile strength, a strip with a longitudinal width of 15 mm was cut and clamped at both ends of the fixture, and the speed of the stretching machine was set to 200 mm / min. When testing the longitudinal tensile strength of the microporous membrane, a strip with a transverse width of 15 mm was cut and tested. Other parameter settings were kept consistent with the conditions for testing transverse tensile strength. The puncture strength can be determined by referring to GB / T 36363-2018. After flattening and clamping the microporous membrane sample, puncture it at a rate of 300 mm / min and measure the puncture strength data. The heat shrinkage rate can be tested as follows: cut the microporous membrane into a 297 mm × 210 mm sample block, draw a 100 mm × 100 mm frame in the middle, place it between 22 A4 sheets of paper (11 A4 sheets on the top and bottom), and then place it in a 150℃ constant temperature oven for 1 hour. After the heat shrinkage rate is determined, remove it and let it cool to room temperature (25℃). Measure the side length of the frame and take the average value L. The heat shrinkage rate is calculated as (100-L) / 100 × 100%. Oil absorption can be evaluated by, for example, by testing 2 μL of paraffin oil (40℃, viscosity 45±5 cp) onto a 10cm×10cm membrane surface and observing the diffusion area for 5 minutes. A larger diffusion area indicates higher oil absorption, and the percentage of the diffusion area to the total membrane surface area characterizes the oil absorption. Stiffness is measured according to GB / T 41567. Specifically, the slot width is 10.0 mm. The microporous membrane is placed on the sample stage and the slot is covered, with 1 / 3 of the microporous membrane in front of the slot and 2 / 3 behind it. The microporous membrane is pressed into the slot with a test head to complete one test and then returned to the initial position. The maximum force required for this process characterizes the stiffness of the microporous membrane. Moisture permeability can be tested using the positive cup method of GB / T 12704.1.

[0263] Table 4 Characterization of the microporous membranes in each embodiment and comparative example

[0264] The experimental data above show that the microporous membrane prepared using the embodiments of this application has better TD strength, puncture strength, oil absorption rate, softness, and moisture permeability compared to the comparative example. Furthermore, by optimizing the content and type of the first and second ionic liquids, the strength, oil absorption rate, softness, and moisture permeability of the microporous membrane can be further improved.

[0265] Specifically, the microporous membrane of Comparative Example 1 uses a traditional process (paraffin oil pore-forming agent + DCM extractant) and does not contain ionic liquid; its performance is inferior to that of the examples. In Comparative Examples 2 and 4, the microporous membranes contain excessive ionic liquid, resulting in inferior performance compared to the examples. In Comparative Example 3, the microporous membrane does not contain the first ionic liquid (i.e., the pore-forming agent is paraffin oil) and only contains the second ionic liquid; its performance is inferior to that of the examples.

[0266] Furthermore, as can be seen from Examples 1-5, optimizing the ionic liquid content is beneficial to further improving the performance of the microporous membrane. As can be seen from Examples 6-9 and Example 1, adjusting the HLB difference between the first and second ionic liquids is beneficial to further improve the pore size uniformity of the microporous membrane and better control its porosity, thereby further improving the moisture permeability of the clothing fabric.

[0267] As can be seen from Examples 11 and 1, using a second ionic liquid as the extractant, compared with using dichloromethane as the extractant, is beneficial to further improve the overall performance of the microporous membrane.

[0268] As can be seen from Examples 12-14 and Example 1, controlling the mass percentage of the second ionic liquid within a certain range is beneficial to further improve the breathability of the product. Therefore, when applied to the field of clothing fabrics, it is beneficial to further improve the moisture permeability and comfort of the fabric.

[0269] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0270] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A microporous membrane for breathable fabrics, wherein, The microporous membrane contains an ionic liquid, the mass percentage of which is 0.01% to 6%, and the permeability of which is 10 sec / 100cc to 60 sec / 100cc. The ionic liquid includes a first ionic liquid, and the hydrophilic-lipophilic balance value of the first ionic liquid is <10.

2. The microporous membrane according to claim 1, wherein, The first ionic liquid satisfies one or more of the following conditions: (1) The hydrophilic-lipophilic balance value of the first ionic liquid is 0 to 9.8, and can be selected as 3 to 7; (2) The molecular weight of the first ionic liquid is 200 to 1000; (3) The boiling point of the first ionic liquid is 200℃~500℃; (4) The viscosity of the first ionic liquid at 25°C is 20cp~100cp; (5) In the microporous membrane, the mass percentage of the first ionic liquid is 0.01% to 6%, and optionally, the mass percentage of the first ionic liquid is 0.1% to 5%.

3. The microporous membrane according to claim 1 or 2, wherein, The ionic liquid further includes a second ionic liquid, wherein the hydrophilic-lipophilic balance value of the second ionic liquid is greater than that of the first ionic liquid. And / or, the molecular weight of the second ionic liquid is less than the molecular weight of the first ionic liquid.

4. The microporous membrane according to claim 3, wherein, The second ionic liquid satisfies one or more of the following conditions: (1) The difference between the hydrophilic-lipophilic balance value of the second ionic liquid and the hydrophilic-lipophilic balance value of the first ionic liquid is <10, and the difference can be selected as 1 to 9; (2) The hydrophilic-lipophilic balance value of the second ionic liquid is 10-20; (3) The molecular weight of the second ionic liquid is 100 to 250; (4) The boiling point of the second ionic liquid is 100℃~500℃; (5) The viscosity of the second ionic liquid at 25°C is 10cp~50cp; (6) The viscosity of the second ionic liquid at 25°C is 5cp to 20cp lower than that of the first ionic liquid at 25°C; (7) In the microporous membrane, the mass percentage of the second ionic liquid is 0.01% to 3%, and optionally, the mass percentage of the second ionic liquid is 0.1% to 0.5%.

5. The microporous membrane according to claim 3 or 4, wherein, The first ionic liquid and the second ionic liquid are each independently selected from one or more of imidazole salts, pyridine salts, quaternary ammonium salts, quaternary phosphonium salts, and pyrrolidines; Optionally, the first ionic liquid and the second ionic liquid are each independently selected from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium methyl sulfate, 1,3-dimethylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium tetrafluoroborate, 3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium hexafluoroantimonate, 1,3-dimethylimidazolium trifluoromethanesulfonate, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium perchlorate, and 1,3-dimethylimidazolium nitrate. One or more of the following: 1,3-dimethylimidazolium methanesulfonate, 1,3-dimethylimidazolium p-toluenesulfonate, 1,3-dimethylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluoroantimonate.

6. The microporous membrane according to any one of claims 1 to 5, wherein, The microporous membrane includes homopolymers or copolymers of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and norbornene, thermoplastic polyurethane elastomers, polyolefin elastomers, polyethylene terephthalate, polyurethane or a mixture of their polymers. Optionally, the microporous membrane comprises one or more of polyethylene, polypropylene, and ethylene-propylene copolymer; Optionally, the viscosity-average molecular weight of the microporous membrane is 100,000 to 900,000.

7. The microporous membrane according to any one of claims 1 to 6, wherein, The microporous membrane also contains additives, including one or more of antioxidants, metal soaps, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments. Optionally, in the microporous membrane, the additive accounts for 0.01% to 5% of the total mass of the microporous membrane; alternatively, the additive accounts for 0.1% to 1% of the total mass of the microporous membrane. And / or, the microporous membrane comprises multiple layers of sub-membranes stacked together, with different polymers in adjacent sub-membranes, and both containing the first ionic liquid.

8. The microporous membrane according to any one of claims 1 to 7, wherein, The microporous membrane satisfies one or more of the following conditions: (1) The average pore size of the microporous membrane is 20nm to 200nm, and optionally, the average pore size of the microporous membrane is 60nm to 200nm; (2) The transverse tensile strength of the microporous membrane is 500 kgf / cm. 2 ~3000kgf / cm 2 ; (3) The longitudinal tensile strength of the microporous membrane is 1000 kgf / cm. 2 ~3000kgf / cm 2 ; (4) The puncture strength of the microporous membrane is 150 gf to 400 gf; (5) The porosity of the microporous membrane is 10% to 90%, and optionally, the porosity of the microporous membrane is 60% to 90%. (6) The thickness of the microporous membrane is 2μm to 120μm, and optionally, the thickness of the microporous membrane is 3μm to 20μm.

9. A method for preparing a microporous membrane for breathable fabrics, wherein, Includes the following steps: A mixture comprising polymer and ionic liquid is mixed, extruded, and cooled to form an intermediate film. The intermediate membrane is stretched, extracted, and heat-set to obtain the microporous membrane. The ionic liquid in the microporous membrane has a mass percentage of 0.01% to 6%, the air permeability of the microporous membrane is 10 sec / 100cc to 60 sec / 100cc, and the ionic liquid includes a first ionic liquid with a hydrophilic-lipophilic balance value of <10.

10. The method for preparing a microporous membrane according to claim 9, wherein, One or more of the following conditions must be met: (1) The hydrophilic-lipophilic balance value of the first ionic liquid is 0 to 9.8, and can be selected as 3 to 7; (2) The molecular weight of the first ionic liquid is 200 to 1000; (3) The boiling point of the first ionic liquid is 200℃~500℃; (4) The mass ratio of the polymer to the ionic liquid is (5-60):(40-95).

11. The method for preparing a microporous membrane according to claim 9 or 10, wherein, In the extraction step, the extractant includes dichloromethane; or, In the extraction step, the extractant comprises a mixed solvent of a second ionic liquid and water, wherein the second ionic liquid satisfies one or more of the following conditions: (1) The hydrophilic-lipophilic balance value of the second ionic liquid is greater than that of the first ionic liquid; (2) The difference between the hydrophilic-lipophilic balance value of the second ionic liquid and the hydrophilic-lipophilic balance value of the first ionic liquid is <10; (3) The hydrophilic-lipophilic balance value of the second ionic liquid is 10-20; (4) The molecular weight of the second ionic liquid is smaller than that of the first ionic liquid; (5) The molecular weight of the second ionic liquid is 100 to 250; (6) The boiling point of the second ionic liquid is 100℃~500℃; (7) The viscosity of the second ionic liquid at 25°C is 10cp~50cp; (8) The viscosity of the second ionic liquid at 25°C is 5cp to 20cp lower than that of the first ionic liquid at 25°C.

12. The method for preparing a microporous membrane according to claim 11, wherein, The extractant comprises a mixed solvent of a second ionic liquid and water, wherein the mass percentage concentration of the second ionic liquid in the extractant is 5% to 10%. And / or, after the extraction step, the method further includes: washing the extracted microporous membrane intermediate with water, separating it with a reverse osmosis membrane, and drying it; Optionally, the extracted microporous membrane intermediate is washed with water, including a first-stage water wash and a second-stage water wash. The mass percentage concentration of the second ionic liquid in the washing solution of the first-stage water wash is 3% to 5%, and the mass percentage concentration of the second ionic liquid in the washing solution of the second-stage water wash is not higher than 1%, and the mass percentage concentration of the second ionic liquid in the washing solution of the second-stage water wash is not higher than 30 wt% of the mass percentage concentration of the second ionic liquid in the washing solution of the first-stage water wash.

13. The method for preparing a microporous membrane according to any one of claims 9 to 12, wherein, The temperature T of the mixed extrusion 挤 For T 挤 =Polymer melting point T m +(15℃~60℃), optional, T 挤 =Polymer melting point T m +(15℃~45℃); And / or, in the step of mixing and extruding a mixture comprising a polymer and an ionic liquid, the polymer has a melt index of 0.6 g / 10 min to 10 g / 10 min; optionally, the polymer has a melt index of 1.3 g / 10 min to 6 g / 10 min.

14. A breathable fabric, wherein, The breathable fabric includes the microporous membrane according to any one of claims 1 to 8 or the microporous membrane prepared by the preparation method according to any one of claims 9 to 13.

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