Composite microporous membrane as well as preparation method and application thereof

Abstract

The invention discloses a composite microporous membrane as well as a preparation method and application thereof, and belongs to the technical field of microporous membranes. The composite microporous membrane comprises a base membrane and a ceramic layer arranged on at least one side surface of the base membrane, the ceramic layer comprises modified tourmaline, an organic binder, a dispersing agent and a wetting agent; the modified tourmaline is grafted with a chitosan chain segment, and the mass ratio of the chitosan chain segment is 9%-20% by taking the total mass of the modified tourmaline as 100%. The modified tourmaline grafted with a high-content chitosan chain segment is used for the ceramic layer on the surface of the base membrane, so that the influence on the moisture permeation amount can be reduced, the balance between static water resistance and dynamic moisture permeation is realized, and the mechanical strength and antibacterial performance of the base membrane are improved.

Description

Technical Field

[0001] This application relates to the field of microporous membrane technology, and in particular to composite microporous membranes, their preparation methods, and applications. Background Technology

[0002] Microporous membranes possess excellent air permeability, moisture permeability, water resistance, and chemical resistance, making them widely used in industries such as clothing, batteries, biopharmaceuticals, and environmental protection. With technological advancements, the demand for functionalized microporous membranes has become increasingly prominent. Traditional microporous membranes, such as PTFE or PU membranes, have insufficient antibacterial properties, and their application in the clothing industry can easily lead to the growth of large amounts of bacteria (colony count exceeding 10^6) in sweat. 5 CFU / cm²).

[0003] Therefore, it is desirable to develop a composite microporous membrane that improves antibacterial properties while also having high moisture permeability. Summary of the Invention

[0004] Therefore, the main objective of this application is to provide a composite microporous membrane that can improve antibacterial properties while maintaining good moisture permeability and mechanical strength.

[0005] A first aspect of this application provides a composite microporous membrane, comprising a base membrane and a ceramic layer disposed on at least one surface of the base membrane; said ceramic layer comprises modified tourmaline, an organic binder, a dispersant, and a wetting agent;

[0006] The modified tourmaline is grafted with chitosan segments, and the chitosan segments account for 9%-20% of the total mass of the modified tourmaline (100%).

[0007] The modified tourmaline grafted with the above-mentioned material contains a high content of chitosan segments. On the one hand, the presence of chitosan segments can improve the dispersibility of tourmaline through steric hindrance and entanglement between molecular chains, thereby enhancing the degree of functional modification of tourmaline. On the other hand, chitosan has good compatibility with organic binders and possesses antibacterial properties; tourmaline grafted with chitosan exhibits improved compatibility and antibacterial activity. Therefore, by setting a ceramic layer containing the defined modified tourmaline on the surface of the base membrane, this application can reduce the impact on moisture permeability, achieve a balance between static waterproofing and dynamic moisture permeability, and improve the mechanical strength and antibacterial properties of the base membrane. Thus, the composite microporous membrane of this application possesses excellent antibacterial properties and high moisture permeability.

[0008] In some embodiments, in the modified tourmaline, tourmaline and chitosan segments are connected by segments formed by an amino-containing silane coupling agent and a dialdehyde;

[0009] Optionally, the raw materials for preparing the modified tourmaline include pretreated tourmaline, an amino-containing silane coupling agent, dialdehyde, and chitosan.

[0010] Optionally, the mass ratio of pretreated tourmaline, amino-containing silane coupling agent, dialdehyde and chitosan is 100:(1-3.5):(0.5-2):(16-32).

[0011] In some embodiments, the method for preparing the modified tourmaline includes the following steps:

[0012] Tourmaline was subjected to azeotropic distillation of alcohol and water to prepare pretreated tourmaline.

[0013] The pretreated tourmaline was grafted sequentially with an amino-containing silane coupling agent, dialdehyde, and chitosan to prepare the modified tourmaline.

[0014] In some embodiments, one or more of the following features are satisfied:

[0015] (1) The tourmaline includes at least one of Bouguer tourmaline, magnesium tourmaline, iron tourmaline, lithium tourmaline, iron-magnesium tourmaline, calcium-magnesium tourmaline, black tourmaline and calcium-lithium tourmaline;

[0016] (2) The amino-containing silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane;

[0017] (3) The dialdehyde includes at least one of glutaraldehyde, glyoxal, heptaaldehyde, and succinaldehyde:

[0018] (4) The number average molecular weight of the chitosan is 30kDa-120kDa.

[0019] In some embodiments, one or more of the following features are satisfied:

[0020] (1) The alcohol includes at least one of ethanol and isopropanol;

[0021] (2) The mass ratio of the water to the alcohol is 1:(0.3-3);

[0022] (3) Based on a total mass of tourmaline, alcohol and water of 100 wt%, the mass percentage of tourmaline is 9%-20%;

[0023] (4) The conditions for azeotropic distillation include: time 3h-6h;

[0024] (5) The steps of sequentially grafting the pretreated tourmaline with an amino-containing silane coupling agent, dialdehyde, and chitosan include:

[0025] Pretreated tourmaline was subjected to a first grafting reaction with an amino-containing silane coupling agent to prepare aminated tourmaline.

[0026] Aldehyde-modified tourmaline is prepared by a second grafting reaction between aminated tourmaline and dialdehyde.

[0027] The modified tourmaline was prepared by subjecting aldehyde-modified tourmaline to a third grafting reaction with chitosan.

[0028] In some embodiments, one or more of the following features are satisfied:

[0029] (1) The conditions for the first grafting reaction include: reaction temperature 70℃-80℃; reaction time 2h-4h;

[0030] (2) The first grafting reaction is carried out in the presence of the first solvent;

[0031] Optionally, the first solvent includes at least one of ethanol, toluene, and acetone;

[0032] Optionally, the volume-to-mass ratio of the first solvent to the pretreated tourmaline is (10-30) mL:1 g;

[0033] (3) The conditions for the second grafting reaction include: reaction temperature 20℃-30℃; reaction time 1h-2h;

[0034] (4) The second grafting reaction is carried out in the presence of the second solvent;

[0035] Optionally, the pH of the second solvent is 3-6;

[0036] Optionally, the second solvent includes at least one of a phosphate buffer solution with pH=5 and an acetate-sodium acetate buffer solution with pH=5;

[0037] Optionally, the volume-to-mass ratio of the second solvent to ammonified tourmaline is (1-2) mL: 1 g;

[0038] (5) The conditions for the third grafting reaction include: reaction temperature 50℃-60℃; reaction time 4h-6h;

[0039] (6) The third grafting reaction is carried out in the presence of a third solvent;

[0040] Optionally, the pH of the third solvent is 3-6;

[0041] Optionally, the third solvent includes at least one of an acetate buffer solution with pH=4.5, a phosphate buffer solution with pH=4.5, and an acetate-sodium acetate solution with pH=4.5;

[0042] Optionally, the volume-to-mass ratio of the third solvent to chitosan is 100 mL:(0.5-2.5) g.

[0043] In this application, azeotropic distillation is achieved at atmospheric pressure (101.3 kPa). The temperature of azeotropic distillation is not particularly limited and can be adjusted according to the type of alcohol.

[0044] In some embodiments, one or more of the following features are satisfied:

[0045] (1) In the ceramic layer, the mass ratio of modified tourmaline, organic binder, dispersant and wetting agent is (13-23):(7-15):(0.05-0.4):(0.01-0.6);

[0046] (2) The D50 particle size of the modified tourmaline is 0.5μm-1.5μm.

[0047] This application does not specifically limit the type of organic binder. For example, the organic binder may be selected from at least one of polyvinyl alcohol, polyacrylonitrile, polyacrylic acid, polyacrylate and polymethyl methacrylate.

[0048] This application does not specifically limit the type of dispersant. For example, the dispersant includes at least one of polyacrylamide, sodium alkylaryl sulfonate, sodium alkyl sulfate, sodium secondary alkyl sulfate, sodium alkyl sulfonate, and fatty acid polyoxyethylene ester.

[0049] This application does not specifically limit the type of wetting agent. For example, the wetting agent includes at least one of sodium dodecyl sulfate, sodium hydroxyethyl sulfate, polyether modified siloxane, fatty alcohol polyoxyethylene ether, and sodium butadiene naphthalene sulfonate.

[0050] In some embodiments, one or more of the following features are satisfied:

[0051] (1) The base film is made of at least one of polypropylene, polyethylene, polytetrafluoroethylene, polyester and polyurethane;

[0052] (2) The thickness of the ceramic layer is 0.5μm-4μm;

[0053] (3) The thickness of the base film is 5μm-20μm.

[0054] The second aspect of this application provides a method for preparing a composite microporous membrane, comprising the following steps:

[0055] Tourmaline was subjected to azeotropic distillation of alcohol and water to prepare pretreated tourmaline.

[0056] The pretreated tourmaline was grafted sequentially with an amino-containing silane coupling agent, dialdehyde, and chitosan to prepare the modified tourmaline.

[0057] The composite microporous membrane is prepared by coating a ceramic layer slurry comprising modified tourmaline, organic binder, dispersant, wetting agent and solvent onto at least one side surface of a base membrane to form a ceramic layer.

[0058] The alcohol includes at least one of ethanol and isopropanol.

[0059] Tourmaline is a boron-containing cyclic silicate mineral with a silicon-oxygen ring in its crystal structure. The inventors discovered that during azeotropic distillation of alcohol and water, ethanol or isopropanol can promote the hydrolysis of the silicon-oxygen rings on tourmaline, generating Si-OH and Si-OR. Si-OR further hydrolyzes to Si-OH under the action of water, while boron oxides also hydrolyze to form B-OH. Simultaneously, the vapor generated during the azeotropic distillation process forms a protective layer on the tourmaline surface, preventing the Si-OH generated from the tourmaline from extensively condensing into silicon-oxygen-silicon (Si-O-Si) bonds. Therefore, the hydroxyl density on the tourmaline surface after azeotropic distillation pretreatment is significantly increased, which is beneficial for grafting reactions with amino-containing silane coupling agents, dialdehydes, and chitosan, and promotes the full progress of each grafting reaction, improving the degree of graft modification of tourmaline. The prepared modified tourmaline contains a greater number of chitosan segments.

[0060] The presence of chitosan segments can improve the dispersibility of tourmaline through steric hindrance and entanglement between molecular chains, thereby enhancing the degree of functional modification. Furthermore, chitosan exhibits good compatibility with organic binders and possesses antibacterial properties; tourmaline grafted with chitosan demonstrates improved compatibility and antibacterial activity. In summary, improving the dispersibility of tourmaline through multiple mechanisms facilitates its functional expression and enhances its antibacterial performance.

[0061] Therefore, by preparing a ceramic layer containing the specified modified tourmaline on the surface of the base film, this application can reduce the impact on moisture permeability, achieve a balance between static waterproofing and dynamic moisture permeability, and improve the mechanical strength and antibacterial properties of the base film.

[0062] Furthermore, the above preparation method can effectively control the degree of tourmaline grafting modification and promote the full progress of the grafting reaction, reduce the durability loss and yellowing caused by free aldehyde groups, and optimize the overall performance of the composite microporous membrane.

[0063] In some embodiments, one or more of the following features are satisfied:

[0064] (1) The solid content of the ceramic layer slurry is 25%-35%;

[0065] (2) The solvent includes water.

[0066] A third aspect of this application provides the application of the composite microporous membrane described in the first aspect or the composite microporous membrane prepared by the preparation method described in the second aspect in clothing, medical supplies, filtration devices or separation devices.

[0067] The beneficial effects of this application are:

[0068] 1. The modified tourmaline grafted in this application has a high content of chitosan segments. On the one hand, the presence of chitosan segments can improve the dispersibility of tourmaline through steric hindrance and entanglement between molecular chains, thereby enhancing the degree of functional modification of tourmaline. On the other hand, chitosan has good compatibility with organic binders and possesses antibacterial properties; tourmaline grafted with chitosan exhibits improved compatibility and antibacterial activity. Therefore, by setting a ceramic layer containing the defined modified tourmaline on the surface of the base film, this application can reduce the impact on moisture permeability, achieve a balance between static waterproofing and dynamic moisture permeability, and improve the mechanical strength and antibacterial properties of the base film, as well as enhance its self-heating performance.

[0069] 2. The composite microporous membrane of this application has excellent antibacterial properties and high moisture permeability. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of this application clearer and to provide a more thorough and comprehensive understanding of the disclosure of this application, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. The described embodiments are only a part of the embodiments of this application, and not all of them.

[0071] The implementation of this application is described in detail below. This embodiment is implemented based on the technical solution of this application, and provides detailed implementation methods and specific operation processes, but the protection scope of this application is not limited to the following embodiment.

[0072] 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 is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0073] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0074] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" or "at least one" means one or more of two.

[0075] In this application, terms such as "further" and "especially" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0076] 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.

[0077] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, including the two endpoint integers of the numerical range, as well as every integer between the two endpoints, is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include numerical interval types such as percentage intervals, ratio intervals, and proportion intervals.

[0078] In this application, the mass percentage of chitosan segments = (mass of modified tourmaline - mass of aldehyde-modified tourmaline) / mass of modified tourmaline × 100%.

[0079] In this application, the number-average molecular weight can be determined by methods such as gas phase permeation or gel permeation chromatography.

[0080] In this application, D50, also known as median diameter or median particle size, refers to the particle size value corresponding to a cumulative percentage of 50% on the cumulative particle size distribution curve, which can be determined by laser scattering.

[0081] In this application, unless otherwise specified, the temperature parameters are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control. Fluctuations are permitted within ranges such as ±5℃, ±4℃, ±3℃, ±2℃, and ±1℃.

[0082] By padding or coating a slurry containing tourmaline and organic binders onto the surface of fabrics, microporous membranes can be functionalized and their antibacterial properties improved. However, due to the high surface polarity of tourmaline powder, it is prone to agglomeration and has poor compatibility with organic binders (contact angle > 100°). Even with the addition of a large amount of dispersant, it is difficult to achieve good dispersion, often resulting in uneven dispersion. This leads to blockage of the moisture permeability channels and a significant decrease in the moisture permeability of the microporous membrane (e.g., < 8000 g / m³). 2 (24h), it is difficult to achieve a balance between static waterproofing and dynamic breathability, and the degree of functional modification is also quite limited.

[0083] Based on this, this application provides a composite microporous membrane, its preparation method and application, in order to improve its antibacterial properties while maintaining the good moisture permeability and mechanical strength of the base membrane.

[0084] A first aspect of this application provides a composite microporous membrane, comprising a base membrane and a ceramic layer disposed on at least one surface of the base membrane; said ceramic layer comprises modified tourmaline, an organic binder, a dispersant, and a wetting agent;

[0085] The modified tourmaline is grafted with chitosan segments, and the chitosan segments account for 9%-20% of the total mass of the modified tourmaline (100%).

[0086] The modified tourmaline grafted with the above-mentioned material contains a high content of chitosan segments. On the one hand, the presence of chitosan segments can improve the dispersibility of tourmaline through steric hindrance and entanglement between molecular chains, thereby enhancing the degree of functional modification of tourmaline. On the other hand, chitosan has good compatibility with organic binders and possesses antibacterial properties; tourmaline grafted with chitosan exhibits improved compatibility and antibacterial activity. Therefore, by setting a ceramic layer containing the defined modified tourmaline on the surface of the base membrane, this application can reduce the impact on moisture permeability, achieve a balance between static waterproofing and dynamic moisture permeability, and improve the mechanical strength and antibacterial properties of the base membrane, as well as enhance its self-heating performance. Thus, the composite microporous membrane of this application possesses excellent antibacterial properties and high moisture permeability.

[0087] In some embodiments, based on the total mass of modified tourmaline as 100%, the mass percentage of chitosan segments can be selected as 9%-18%, specifically 9%, 10%, 12%, 14%, 16%, 18%, 20%, etc.

[0088] In some embodiments, in the modified tourmaline, tourmaline and chitosan segments are connected by segments formed by an amino-containing silane coupling agent and a dialdehyde;

[0089] Optionally, the raw materials for preparing the modified tourmaline include pretreated tourmaline, an amino-containing silane coupling agent, dialdehyde, and chitosan.

[0090] Optionally, the mass ratio of pretreated tourmaline, amino-containing silane coupling agent, dialdehyde, and chitosan is 100:(1-3.5):(0.5-2):(16-32), or alternatively 100:(1.5-3.5):(1-2):(18-25.3), for example 100:(1, 2, 3, or 3.5):(0.5, 1, 1.5, or 2):(16, 20, 24, 28, or 32).

[0091] In some embodiments, the method for preparing the modified tourmaline includes the following steps:

[0092] Tourmaline was subjected to azeotropic distillation of alcohol and water to prepare pretreated tourmaline.

[0093] The pretreated tourmaline was grafted sequentially with an amino-containing silane coupling agent, dialdehyde, and chitosan to prepare the modified tourmaline.

[0094] In some embodiments, one or more of the following features are satisfied:

[0095] (1) The tourmaline includes at least one of Bouguer tourmaline, magnesium tourmaline, iron tourmaline, lithium tourmaline, iron-magnesium tourmaline, calcium-magnesium tourmaline, black tourmaline and calcium-lithium tourmaline;

[0096] (2) The amino-containing silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane;

[0097] (3) The dialdehyde includes at least one of glutaraldehyde, glyoxal, heptaaldehyde, and succinaldehyde;

[0098] (4) The number average molecular weight of the chitosan is 30kDa-120kDa, for example 30kDa, 40kDa, 60kDa, 80kDa, 100kDa, 120kDa, etc.

[0099] In some embodiments, the tourmaline has a D50 particle size of 0.5μm-1.5μm, such as 0.5μm, 0.7μm, 1μm, 1.2μm, 1.5μm, etc.

[0100] In some embodiments, the tourmaline has a hydroxyl density of 5 OH groups. - / nm 2 ~7 OH - / nm 2 For example, 5 OH groups - / nm 2 6 OH - / nm2 6.5 OH groups - / nm 2 7 OH - / nm 2 wait.

[0101] In some embodiments, the pretreated tourmaline has a hydroxyl density of 7 OH groups. - / nm 2 ~10 OH - / nm 2 For example, 7 OH groups - / nm 2 8 OH - / nm 2 9 OH - / nm 2 10 OH - / nm 2 wait.

[0102] In some embodiments, one or more of the following features are satisfied:

[0103] (1) The alcohol includes at least one of ethanol and isopropanol;

[0104] (2) The mass ratio of water to alcohol is 1:(0.3-3), for example 1:0.3, 1:0.5, 1:1, 1:2, 1:3, etc.;

[0105] (3) Based on the total mass of tourmaline, alcohol and water as 100wt%, the mass percentage of tourmaline is 9%-20%, such as 9%, 10%, 12%, 14%, 16%, 18%, 20% etc.;

[0106] (4) The conditions for azeotropic distillation include: time 3h-6h, such as 3h, 4h, 5h, 6h, etc.;

[0107] (5) The steps of sequentially grafting the pretreated tourmaline with an amino-containing silane coupling agent, dialdehyde, and chitosan include:

[0108] Pretreated tourmaline was subjected to a first grafting reaction with an amino-containing silane coupling agent to prepare aminated tourmaline.

[0109] Aldehyde-modified tourmaline is prepared by a second grafting reaction between aminated tourmaline and dialdehyde.

[0110] The modified tourmaline was prepared by subjecting aldehyde-modified tourmaline to a third grafting reaction with chitosan.

[0111] In some embodiments, one or more of the following features are satisfied:

[0112] (1) The conditions for the first grafting reaction include: reaction temperature 70℃-80℃, such as 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, etc.; reaction time 2h-4h, such as 2h, 3h, 4h, etc.

[0113] (2) The first grafting reaction is carried out in the presence of the first solvent;

[0114] Optionally, the first solvent includes at least one of ethanol, toluene, and acetone;

[0115] Optionally, the volume-to-mass ratio of the first solvent to the pretreated tourmaline is (10-30) mL:1g, for example, 10 mL:1g, 15 mL:1g, 20 mL:1g, 25 mL:1g, 30 mL:1g, etc.

[0116] (3) The conditions for the second grafting reaction include: reaction temperature 20℃-30℃, such as 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, etc.; reaction time 1h-2h, such as 1h, 1.5h, 2h, etc.

[0117] (4) The second grafting reaction is carried out in the presence of the second solvent;

[0118] Optionally, the pH of the second solvent is 3-6, such as 3, 4, 5 or 6;

[0119] Optionally, the second solvent includes at least one of a phosphate buffer solution with pH=5 and an acetate-sodium acetate buffer solution with pH=5;

[0120] Optionally, the volume-to-mass ratio of the second solvent to ammonified tourmaline is (1-2) mL:1g, for example, 1 mL:1g, 1.5 mL:1g, 2 mL:1g, etc.

[0121] (5) The conditions for the third grafting reaction include: reaction temperature 50℃-60℃, such as 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, etc.; reaction time 4h-6h, such as 4h, 5h, 6h, etc.

[0122] (6) The third grafting reaction is carried out in the presence of a third solvent;

[0123] Optionally, the pH of the third solvent is 3-6, such as 3, 4, 5 or 6;

[0124] Optionally, the third solvent includes at least one of an acetate buffer solution with pH=4.5, a phosphate buffer solution with pH=4.5, and an acetate-sodium acetate solution with pH=4.5;

[0125] Optionally, the volume-to-mass ratio of the third solvent to chitosan is 100mL:(0.5-2.5)g, such as 100mL:0.5g, 100mL:1g, 100mL:1.5g, 100mL:2g, 100mL:2.5g, etc.

[0126] In this application, azeotropic distillation is performed at atmospheric pressure (101.3 kPa). The azeotropic distillation temperature is not specifically limited and can be adjusted according to the type of alcohol. For example, the azeotropic temperature of a mixture of ethanol and water at standard atmospheric pressure (101.3 kPa) is 78.15℃, that of a mixture of isopropanol and water at standard atmospheric pressure (101.3 kPa) is 80.18℃, and that of a mixture of n-butanol and water at standard atmospheric pressure (101.3 kPa) is 92℃. Accordingly, during azeotropic distillation, the treatment temperature should be maintained around its azeotropic temperature, with a deviation of ±1℃ allowed.

[0127] It should be noted that if the mass ratio of chitosan is too high, the solution viscosity will increase, the dispersibility will become worse, and the steric hindrance will be aggravated, which will affect the grafting rate of chitosan and cause chitosan and tourmaline to agglomerate, resulting in a deterioration of the mechanical properties of the composite microporous membrane.

[0128] In some embodiments, one or more of the following features are satisfied:

[0129] (1) In the ceramic layer, the mass ratio of modified tourmaline, organic binder, dispersant and wetting agent is (13-23):(7-15):(0.05-0.4):(0.01-0.6), for example (13, 15, 17, 19 or 23):(7, 9, 11, 13 or 15):(0.05, 0.1, 0.2, 0.3 or 0.4):(0.01, 0.05, 0.1, 0.2, 0.4 or 0.6);

[0130] (2) The organic binder includes at least one of polyvinyl alcohol, polyacrylonitrile, polyacrylic acid, polyacrylate and polymethyl acrylate;

[0131] (3) The dispersant includes at least one of polyacrylamide, sodium alkylaryl sulfonate, sodium alkyl sulfate, sodium secondary alkyl sulfate, sodium alkyl sulfonate and fatty acid polyoxyethylene ester;

[0132] (4) The wetting agent includes at least one of sodium dodecyl sulfate, sodium hydroxyethyl sulfate, polyether modified siloxane, fatty alcohol polyoxyethylene ether, and sodium butadiene naphthalene sulfonate;

[0133] (5) The D50 particle size of the modified tourmaline is 0.5μm-1.5μm, for example 0.5μm, 0.7μm, 1μm, 1.2μm, 1.5μm, etc.

[0134] In some embodiments, one or more of the following features are satisfied:

[0135] (1) The base film is made of at least one of polypropylene, polyethylene, polytetrafluoroethylene, polyester and polyurethane;

[0136] (2) The thickness of the ceramic layer is 0.5μm-4μm, for example 0.5μm, 1μm, 2μm, 4μm, etc.;

[0137] (3) The thickness of the base film is 5μm-20μm, for example 5μm, 6μm, 8μm, 10μm, 15μm, 17μm, 19μm, 20μm, etc.

[0138] The second aspect of this application provides a method for preparing a composite microporous membrane, comprising the following steps:

[0139] Tourmaline was subjected to azeotropic distillation of alcohol and water to prepare pretreated tourmaline.

[0140] The pretreated tourmaline was grafted sequentially with an amino-containing silane coupling agent, dialdehyde, and chitosan to prepare the modified tourmaline.

[0141] The composite microporous membrane is prepared by coating a ceramic layer slurry comprising modified tourmaline, organic binder, dispersant, wetting agent and solvent onto at least one side surface of a base membrane to form a ceramic layer.

[0142] The alcohol includes at least one of ethanol and isopropanol.

[0143] Tourmaline is a boron-containing cyclic silicate mineral with a silicon-oxygen ring in its crystal structure. The inventors discovered that during azeotropic distillation of alcohol and water, ethanol or isopropanol can promote the hydrolysis of the silicon-oxygen rings on tourmaline, generating Si-OH and Si-OR. Si-OR further hydrolyzes to Si-OH under the action of water, while boron oxides also hydrolyze to form B-OH. Simultaneously, the vapor generated during the azeotropic distillation process forms a protective layer on the tourmaline surface, preventing the Si-OH generated from the tourmaline from extensively condensing into silicon-oxygen-silicon (Si-O-Si) bonds. Therefore, the hydroxyl density on the tourmaline surface after azeotropic distillation pretreatment is significantly increased, which is beneficial for grafting reactions with amino-containing silane coupling agents, dialdehydes, and chitosan, and promotes the full progress of each grafting reaction, improving the degree of graft modification of tourmaline. The prepared modified tourmaline contains a greater number of chitosan segments.

[0144] The presence of chitosan segments can improve the dispersibility of tourmaline through steric hindrance and entanglement between molecular chains, thereby enhancing the degree of functional modification. Furthermore, chitosan exhibits good compatibility with organic binders and possesses antibacterial properties; tourmaline grafted with chitosan demonstrates improved compatibility and antibacterial activity. In summary, improving the dispersibility of tourmaline through multiple mechanisms facilitates its functional expression and enhances its antibacterial performance.

[0145] Therefore, by preparing a ceramic layer containing the specified modified tourmaline on the surface of the base film, this application can reduce the impact on moisture permeability, achieve a balance between static waterproofing and dynamic moisture permeability, and improve the mechanical strength and antibacterial properties of the base film.

[0146] Furthermore, the above preparation method can effectively control the degree of tourmaline grafting modification and promote the full progress of the grafting reaction, reduce the durability loss and yellowing caused by free aldehyde groups, and optimize the overall performance of the composite microporous membrane.

[0147] In some embodiments, one or more of the following features are satisfied:

[0148] (1) The solid content of the ceramic layer slurry is 25%-35%, for example, 25%, 30%, 35%, etc.;

[0149] (2) The solvent includes water.

[0150] A third aspect of this application provides the application of the composite microporous membrane described in the first aspect or the composite microporous membrane prepared by the preparation method described in the second aspect in clothing, medical supplies, filtration devices or separation devices.

[0151] Understandably, the composite microporous membrane of this application has excellent antibacterial properties and high moisture permeability, making it suitable for use in outdoor clothing, sportswear, and other garments, as well as casual wear and fashion apparel.

[0152] It is worth noting that the raw materials used in the embodiments of this application are all ordinary commercially available products, and their sources are not specifically limited.

[0153] The following is an exemplary description of some of the raw materials used in the examples and comparative examples:

[0154] Tourmaline powder: Dv50 is 0.7μm, tourmaline hydroxyl group density is 6.4 OH groups. - / nm 2 Purchased from Shijiazhuang Huabang Mineral Products Co., Ltd.

[0155] Amino-containing silane coupling agent: brand name A107147, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0156] Glutaraldehyde: Grade G105905-2.5L, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0157] Phenylan: Grade G818021, purchased from Maclean's Reagent Co., Ltd.;

[0158] Chitosan: Grade MC100015, purchased from Maclean's Reagent Co., Ltd., molecular weight 50kDa;

[0159] Chitosan: Brand name MC200015, purchased from Maclean's Reagent Co., Ltd., molecular weight 80kDa;

[0160] Dispersant: Polyacrylamide, model Disperbyk-190, purchased from BYK Chemicals;

[0161] Organic binder: polyacrylate, model LIB-106P, purchased from Guangzhou Senrui;

[0162] Wetting agent: polyether-modified siloxane BYK-349, purchased from BYK Chemicals;

[0163] Microporous membrane: Model SQ209F, purchased from Xingyuan Material (Nantong) New Material Co., Ltd., with a thickness of 9μm.

[0164] The following are specific embodiments and comparative examples.

[0165] Example 1

[0166] 1) Preparation of modified tourmaline:

[0167] Pretreatment: Add 100g of tourmaline powder to 290g of water and stir at 1000rpm for 30min to obtain tourmaline dispersion. Add 490g of ethanol to the tourmaline dispersion and continue stirring at 500rpm for 10min. Then, perform azeotropic distillation for 5h. Wash the solid with 20mL of anhydrous ethanol and dry to obtain pretreated tourmaline.

[0168] Ammoniation: Dissolve 3g of amino-containing silane coupling agent (KH-550) in 2500mL of ethanol, then add 100g of pretreated tourmaline, stir at 800rpm, and react at 75℃ for 3h in a nitrogen atmosphere. After centrifugation, wash repeatedly with anhydrous ethanol, and filter to obtain ammonified tourmaline.

[0169] Aldehydeization: 150 mL of acetic acid buffer solution with pH 5 and 1.5 g of dialdehyde (glutaraldehyde) were mixed, and then the aminated tourmaline obtained in the above reaction was added. The mixture was reacted at room temperature (25 °C) for 1.5 h to obtain aldehyde-modified tourmaline.

[0170] Chitosan grafting: Add 1250 mL of acetic acid buffer solution with pH 4.5 to the above dispersion of aldehyde-containing tourmaline, stir and adjust the pH of the system to about 4.5, then add 25 g of chitosan (50 kDa), react at 55 °C for 5 h, repeatedly wash with deionized water and centrifuge until the supernatant is colorless and transparent and free of chitosan, dry at 60 °C for 24 h to obtain the modified tourmaline powder.

[0171] 2) Preparation of ceramic layer slurry: The modified tourmaline, organic binder, dispersant and wetting agent were mixed in a mass ratio of 19:9:0.08:0.06, and water was added to prepare a ceramic layer slurry with a solid content of 30wt%.

[0172] 3) Preparation of composite microporous membranes:

[0173] The ceramic layer slurry obtained in step (2) was coated on one side of the base membrane (model SQ209F microporous membrane, thickness 9μm), and dried in an oven at 75℃ for 20s to form a ceramic layer (thickness 2μm) to obtain a composite microporous membrane.

[0174] Example 2-11

[0175] Except for the difference in raw material composition and process parameters, the rest is the same as in Example 1, as shown in Table 1 (the contents not shown in Table 1 are the same as in Example 1).

[0176] Comparative Example 1

[0177] Except for the use of n-butanol instead of ethanol for azeotropic distillation, the rest is the same as in Example 1.

[0178] Comparative Example 2

[0179] Except for not pre-treating the tourmaline (azeotropic distillation) and directly using tourmaline for ammoniation, aldehyde modification and chitosan grafting, the rest is the same as in Example 1.

[0180] Comparative Example 3

[0181] Except for not performing any further modifications (ammoniation, aldehyde modification, and chitosan grafting) on ​​the pretreated tourmaline, the rest is the same as in Example 1.

[0182] Comparative Example 4

[0183] Except for the different raw material composition, the rest is the same as in Example 1, as shown in Table 1 (the contents not shown in Table 1 are the same as in Example 1).

[0184] Test case

[0185] 1. Hydroxyl density of tourmaline:

[0186] By chemical titration, tourmaline powder of known mass and surface area before and after activation is reacted with an excess of an active reagent of known concentration (such as CH3MgI Grignard reagent), which quantitatively reacts with the -OH groups on the surface. After the reaction is complete, the amount of unreacted Grignard reagent is measured by titration. The number of moles of surface hydroxyl groups is calculated from the amount of Grignard reagent consumed.

[0187] 2. Performance characterization of composite microporous membranes:

[0188] 1) Tensile strength: The longitudinal tensile strength MD and transverse tensile strength TD of the base membrane and composite microporous membrane were tested using the Chinese tensile testing machine EM6.202, and the test standard was GB / T 1040.3-2006;

[0189] 2) Moisture permeability: The membrane was tested according to Method B of GB / T 12704.2 a;

[0190] 3) Negative ion emission: According to GB / T 45796-2025 standard, the emission was measured by the Japanese COM-3200PROII air negative ion tester in a closed test chamber using the capacitive inhalation method.

[0191] 4) Antibacterial performance: According to the CLSI M2 standard, Staphylococcus aureus (ATCC 6538) was used as the test bacteria, and the diameter of the inhibition zone was determined by the agar diffusion method. It can be understood that the larger the diameter of the inhibition zone, the better the antibacterial performance of the composite microporous membrane.

[0192] Table 1 Summary of parameters and performance of the examples and comparative examples

[0193]

[0194] Table 2 Summary of parameters and performance of the examples and comparative examples (continued)

[0195]

[0196] As can be seen from Tables 1-2, the pretreated tourmaline in Examples 1-11 of this application has an increased hydroxyl density, and the corresponding modified tourmaline has a higher content of chitosan segments. The prepared composite microporous membrane has good mechanical strength, antibacterial properties, negative ion emission properties and high moisture permeability.

[0197] Comparing Example 1 and Comparative Examples 1-2, it can be seen that the mass ratio of chitosan segments has a significant impact on the mechanical strength, antibacterial properties, and moisture permeability of the composite microporous membrane. The mass ratio of chitosan segments can be controlled by adjusting the azeotropic distillation process. Specifically, compared to Comparative Example 2, the use of ethanol in Example 1 or isopropanol and water in Example 2 for azeotropic treatment of tourmaline both increase the hydroxyl density on the tourmaline surface, improving the degree of tourmaline grafting modification, and the prepared modified tourmaline contains more chitosan segments. However, the azeotropic distillation of n-butanol and water in Comparative Example 1 removes adsorbed water molecules and non-bridged hydroxyl groups from the tourmaline surface. Butoxy-substituted hydroxyl groups are chemically adsorbed on the tourmaline surface, which weakens the van der Waals forces between tourmaline particles through steric hindrance, preventing "hard agglomeration." However, this also leads to a decrease in the hydroxyl content on the tourmaline surface, which is detrimental to grafting modification. Therefore, the overall performance of the composite microporous membrane in Comparative Example 1 is significantly worse than that in Example 1.

[0198] Comparing Example 1 and Comparative Example 3, it can be seen that the introduction of chitosan segments greatly improves the mechanical strength, moisture permeability and antibacterial properties of the microporous membrane.

[0199] Comparing Example 1 and Comparative Example 4, it can be seen that an excessively high mass ratio of chitosan segments leads to a significant increase in the size of tourmaline particles, which is detrimental to its moisture permeability and negative ion emission performance.

[0200] 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.

[0201] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope 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 protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A composite microporous membrane, characterized in that, It includes a base film and a ceramic layer disposed on at least one surface of the base film; the ceramic layer includes modified tourmaline, organic binder, dispersant and wetting agent; The modified tourmaline is grafted with chitosan segments, and the chitosan segments account for 9%-20% of the total mass of the modified tourmaline (100%).

2. The composite microporous membrane as described in claim 1, characterized in that, In the modified tourmaline, tourmaline and chitosan segments are connected by segments formed by an amino-containing silane coupling agent and a dialdehyde. Optionally, the raw materials for preparing the modified tourmaline include pretreated tourmaline, an amino-containing silane coupling agent, dialdehyde, and chitosan. Optionally, the mass ratio of pretreated tourmaline, amino-containing silane coupling agent, dialdehyde and chitosan is 100:(1-3.5):(0.5-2):(16-32).

3. The composite microporous membrane as described in claim 2, characterized in that, The preparation method of the modified tourmaline includes the following steps: Tourmaline was subjected to azeotropic distillation of alcohol and water to prepare pretreated tourmaline. The pretreated tourmaline was grafted sequentially with an amino-containing silane coupling agent, dialdehyde, and chitosan to prepare the modified tourmaline.

4. The composite microporous membrane as described in claim 2 or 3, characterized in that, It meets one or more of the following characteristics: (1) The tourmaline includes at least one of Bouguer tourmaline, magnesium tourmaline, iron tourmaline, lithium tourmaline, iron-magnesium tourmaline, calcium-magnesium tourmaline, black tourmaline and calcium-lithium tourmaline; (2) The amino-containing silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; (3) The dialdehyde includes at least one of glutaraldehyde, glyoxal, heptaaldehyde, and succinaldehyde; (4) The number average molecular weight of the chitosan is 30kDa-120kDa.

5. The composite microporous membrane as described in claim 3, characterized in that, It meets one or more of the following characteristics: (1) The alcohol includes at least one of ethanol and isopropanol; (2) The mass ratio of the water to the alcohol is 1:(0.3-3); (3) Based on a total mass of tourmaline, alcohol and water of 100 wt%, the mass percentage of tourmaline is 9%-20%; (4) The conditions for azeotropic distillation include: time 3h-6h; (5) The steps of sequentially grafting the pretreated tourmaline with an amino-containing silane coupling agent, dialdehyde, and chitosan include: Pretreated tourmaline was subjected to a first grafting reaction with an amino-containing silane coupling agent to prepare aminated tourmaline. Aldehyde-modified tourmaline is prepared by a second grafting reaction between aminated tourmaline and dialdehyde. The modified tourmaline was prepared by subjecting aldehyde-modified tourmaline to a third grafting reaction with chitosan.

6. The composite microporous membrane as described in claim 5, characterized in that, It meets one or more of the following characteristics: (1) The conditions for the first grafting reaction include: reaction temperature 70℃-80℃; reaction time 2h-4h; (2) The first grafting reaction is carried out in the presence of the first solvent; Optionally, the first solvent includes at least one of ethanol, toluene, and acetone; Optionally, the volume-to-mass ratio of the first solvent to the pretreated tourmaline is (10-30) mL:1 g; (3) The conditions for the second grafting reaction include: reaction temperature 20℃-30℃; reaction time 1h-2h; (4) The second grafting reaction is carried out in the presence of the second solvent; Optionally, the pH of the second solvent is 3-6; Optionally, the second solvent includes at least one of a phosphate buffer solution with pH=5 and an acetate-sodium acetate buffer solution with pH=5; Optionally, the volume-to-mass ratio of the second solvent to ammonified tourmaline is (1-2) mL: 1 g; (5) The conditions for the third grafting reaction include: reaction temperature 50℃-60℃; reaction time 4h-6h; (6) The third grafting reaction is carried out in the presence of a third solvent; Optionally, the pH of the third solvent is 3-6; Optionally, the third solvent includes at least one of an acetate buffer solution with pH=4.5, a phosphate buffer solution with pH=4.5, and an acetate-sodium acetate solution with pH=4.5; Optionally, the volume-to-mass ratio of the third solvent to chitosan is 100 mL:(0.5-2.5) g.

7. The composite microporous membrane according to any one of claims 1-3, characterized in that, It meets one or more of the following characteristics: (1) In the ceramic layer, the mass ratio of modified tourmaline, organic binder, dispersant and wetting agent is (13-23):(7-15):(0.05-0.4):(0.01-0.6); (2) The D50 particle size of the modified tourmaline is 0.5μm-1.5μm.

8. The composite microporous membrane according to any one of claims 1-3, characterized in that, It meets one or more of the following characteristics: (1) The base film is made of at least one of polypropylene, polyethylene, polytetrafluoroethylene, polyester and polyurethane; (2) The thickness of the ceramic layer is 0.5μm-4μm; (3) The thickness of the base film is 5μm-20μm.

9. A method for preparing a composite microporous membrane, characterized in that, Includes the following steps: Tourmaline was subjected to azeotropic distillation of alcohol and water to prepare pretreated tourmaline. The pretreated tourmaline was grafted sequentially with an amino-containing silane coupling agent, dialdehyde, and chitosan to prepare the modified tourmaline. The composite microporous membrane is prepared by coating a ceramic layer slurry comprising modified tourmaline, organic binder, dispersant, wetting agent and solvent onto at least one side surface of a base membrane to form a ceramic layer. The alcohol includes at least one of ethanol and isopropanol.

10. The preparation method according to claim 9, characterized in that, It meets one or more of the following characteristics: (1) The solid content of the ceramic layer slurry is 25%-35%; (2) The solvent includes water.

11. The application of the composite microporous membrane according to any one of claims 1-8 or the composite microporous membrane prepared by the preparation method according to claim 9 or 10 in clothing, medical products, filtration devices or separation devices.

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