Method for modifying polymer membranes, modified polymer membrane, and filtration apparatus

Abstract

A method for modifying a polymer membrane includes the steps of: pre-wetting the polymer membrane with a crosslinking agent solution containing a first crosslinking agent and a second crosslinking agent; inducing a crosslinking reaction by irradiating the pre-wet polymer membrane; and washing and drying the polymer membrane after the crosslinking reaction to obtain a modified polymer membrane. The polymer membrane modification method of the present invention modifies the polymer membrane using two types of crosslinking agents, forming a 3D network on the surface and body of the polymer membrane to obtain a modified polymer membrane. The modified polymer membrane of the present invention has low protein adsorption, caustic alkali stability, autoclaving stability and gamma ray sterilization stability, and retains overall mechanical properties that can meet the requirements for foldability for filter manufacturing.

Description

[Technical Field]

[0001] This invention belongs to the field of biopharmaceuticals and specifically relates to a method for modifying polymer membranes, modified polymer membranes, and filtration devices. [Background technology]

[0002] Membrane-based filtration technology has become an effective solution for protein separation and purification in the life sciences due to its low-temperature process characteristics, high separation efficiency, and cost-effectiveness. However, protein adsorption to filtration membranes is a long-standing problem, leading not only to a decrease in membrane flux but also to increased operating costs and reduced product yield. In addition to protein adsorption, filtration membranes must also possess caustic alkali stability, autoclavability, and gamma ray sterilization stability, depending on the requirements of the filtration application. Furthermore, the mechanical properties of the filtration membranes must also meet the requirement of foldability for filter manufacturing.

[0003] Conventional technologies primarily improve the performance of filtration membranes through crosslinking reactions between crosslinking agents and monomers, thereby reducing adsorption between the filtration membrane and proteins. A crosslinking agent refers to a compound having two or more reactive functional groups, and these functional groups include, but are not limited to, vinyl groups (double bonds), hydroxyl groups, amide groups, and amino groups. A monomer is a compound having a single functional group in its structure, and these functional groups include, but are not limited to, vinyl groups (double bonds), hydroxyl groups, amide groups, and amino groups.

[0004] To reduce protein adsorption, Hou et al. disclose in U.S. Patent No. 4,921,654 a method for producing a modified microporous membrane having hydroxyl, mercapto, carboxyl, or amino groups. This patent discloses a surface grafting process in which glycidyl methacrylate (GMA) is grafted onto a polymer and then modified by reacting it with 3-hydroxypropyl acrylate (HPA). This patent does not use a crosslinking agent, does not mention the caustic alkali stability of the membrane, and does not evaluate the effect of gamma ray sterilization or autoclaving on protein adsorption.

[0005] Gsell discloses a method for surface modification of a porous polyamide substrate using radiation in U.S. Patent No. 4,906,374. This patent discloses monomers containing at least one hydroxyl group, but does not mention crosslinking agents. The patent does not address the caustic alkali stability of the film, nor does it evaluate the effect of gamma ray sterilization or autoclaving on protein adsorption.

[0006] In another U.S. Patent No. 4,964,989, Gsell provides a hydrophilic porous polymer substrate having a polymer coating to impart low affinity to amide group-containing materials. In U.S. Patent No. 5,019,260, a similar process for modifying PVDF membranes is provided. In both cases, the membrane is modified using a monomer having multiple hydroxyl groups and one type of crosslinking agent, but the caustic alkali stability of the membrane is not mentioned, nor is the effect of gamma ray sterilization or autoclaving on protein adsorption evaluated.

[0007] In U.S. Patent No. 4,944,879, Steuck discloses a method for modifying the surface of a composite porous membrane by electron beam irradiation using one monomer and one crosslinking agent, or one monomer and a pre-coated intermediate polymer. The monomers for which the patent seeks protection include hydroxyalkyl acrylates or methacrylates, acrylamides or methacrylamides, and polar or functionally substituted acrylates or methacrylates. The patent does not mention the caustic alkali stability of the membrane, nor does it evaluate the effect of gamma ray sterilization or autoclaving on protein adsorption.

[0008] Charkoudian et al. (US20030077435A1, EP1779922A1, U.S. Patent No. 7284668B2, U.S. Patent Application US2012 / 028630A1) first seek protection for a method of producing a clean, corrosion-resistant porous membrane with a thermally stable, biomolecular-resistant surface using a terpolymer system comprising two monomers and one crosslinking agent. One of the monomers for which protection is sought is diacetone acrylamide, which does not have strong corrosion stability and is described in its Safety Data Sheet (SDS) as "immiscible with strong bases and strong oxidizing agents."

[0009] In U.S. Patents 2011 / 0244215A1 and 9045602B2, Thom et al. disclose a method for producing a microporous membrane using an oligomer without a crosslinking agent by electron beam crosslinking. Although the modified membrane has low protein adsorption properties, the electron beam dose used in the patent is very high (50-200 kGy, with the protected range being 1-300 kGy), and there is no mention of evaluation of caustic alkali stability and foldability, nor is there any mention of the effect of autoclaving or gamma ray sterilization on protein adsorption properties.

[0010] In summary, conventional modification technologies employ only a technical route in which one type of crosslinking agent reacts with one or more types of monomers. Due to the low caustic alkali stability of acrylic compounds, most modified films have low caustic alkali stability, resulting in a rapid decline in film performance. In US7648034, Charkoudian noted that after immersing a Durapore® film in a pH=13 sodium hydroxide solution for just two hours, the film's water flux decreased by 75%.

[0011] Given these circumstances, it is necessary to provide a method for modifying polymer membranes to obtain high-performance modified polymer membranes by modifying the polymer membrane using two types of crosslinking agents so that the modified membrane has low protein adsorption properties and also possesses caustic alkali stability, autoclaving stability, and gamma ray sterilization stability. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] To overcome the shortcomings of the prior art, one objective of the present invention is to provide a method for modifying polymer membranes, another objective of the present invention is to provide a modified polymer membrane, and yet another objective of the present invention is to provide a filtration device. To achieve the above objectives, the present invention employs the following technical means. [Means for solving the problem]

[0013] According to one aspect of the present invention, A step of pre-wetting the polymer film with a crosslinking agent solution containing a first crosslinking agent and a second crosslinking agent, The steps include: irradiating a pre-moistened polymer film to induce a crosslinking reaction between the first crosslinking agent and the second crosslinking agent in the polymer film, or to induce a crosslinking reaction between the first crosslinking agent, the second crosslinking agent and the polymer film; A method for modifying a polymer film is provided, comprising the steps of washing and drying the polymer film after a crosslinking reaction to obtain a modified polymer film.

[0014] Preferably, when the polymer film, the first crosslinking agent, and the second crosslinking agent are irradiated, free radicals are generated respectively, and a crosslinking reaction occurs between the free radicals to form a 3D crosslinked network on the surface and in the body of the polymer film.

[0015] Preferably, when the first crosslinking agent and the second crosslinking agent are irradiated, free radicals are generated respectively, and a crosslinking reaction occurs between the free radicals to form a 3D crosslinked network on the surface and in the body of the polymer film.

[0016] Preferably, the first crosslinking agent is a hydrophilic organic compound containing two or more first active reaction groups.

[0017] Preferably, the first active reaction group is a bisacrylamide group.

[0018] Preferably, the first active reaction group is at least one of methylene bisacrylamide and ethylidene bisacrylamide.

[0019] Preferably, the second crosslinking agent is a hydrophilic organic compound containing two or more second active reaction groups.

[0020] Preferably, the second active reaction group is an acrylate group.

[0021] Preferably, the second active reaction group contains at least two acrylate bonds.

[0022] Preferably, the concentration of the first crosslinking agent is 0.3 - 0.8 wt%, and the concentration of the second crosslinking agent is 1.0 - 3.0 wt%.

[0023] Preferably, irradiating the pre-wetted polymer film means irradiating the pre-wetted polymer film with at least one of electron beam, X-ray, ultraviolet ray, gamma ray, plasma, and thermal energy.

[0024] Preferably, the dose of the electron beam is 10 to 50 kGy.

[0025] Preferably, an alcohol solution is used for rinsing.

[0026] Preferably, after rinsing is complete, the alcohol solution is replaced with distilled water.

[0027] Preferably, if the polymer film is a hydrophobic film, the crosslinking agent solution further comprises an aqueous solution of a low molecular weight alcohol.

[0028] Preferably, the polymer film is a microporous film.

[0029] Preferably, the polymer film is produced from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer.

[0030] Preferably, the protein adsorption capacity of the modified polymer membrane is 55 μg / cm³. 2 The following applies:

[0031] Preferably, the wetting time of the modified polymer film is 5 seconds or less.

[0032] Preferably, the modified polymer membrane exhibits a change of 20% or less in both water flux and bubble point values ​​compared to the polymer membrane.

[0033] Preferably, the modified polymer film has caustic alkali stability.

[0034] Preferably, after disinfection with a caustic alkali, the modified polymer film has a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption amount of 55 μg / cm³. 2The following applies:

[0035] Preferably, the modified polymer membrane has autoclavability.

[0036] Preferably, after autoclaving, the modified polymer membrane has a wetting time of 5 seconds or less, changes in water flux and bubble point values ​​of 20% or less, and a protein adsorption capacity of 55 μg / cm³. 2 The following applies:

[0037] Preferably, the modified polymer membrane has gamma-ray sterilization stability.

[0038] Preferably, after gamma ray sterilization, the modified polymer membrane has a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption capacity of 55 μg / cm³. 2 The following applies:

[0039] According to another aspect of the present invention, a modified polymer film is provided, which is obtained by modifying a polymer film using the polymer film modification method described above.

[0040] Preferably, the polymer film is a microporous film.

[0041] Preferably, the polymer film is produced from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer.

[0042] Preferably, the protein adsorption capacity of the modified polymer membrane is 55 μg / cm³. 2 The following applies:

[0043] Preferably, the wetting time of the modified polymer film is 5 seconds or less.

[0044] Preferably, the modified polymer membrane exhibits a change of 20% or less in both water flux and bubble point values ​​compared to the polymer membrane.

[0045] Preferably, the modified polymer film has caustic alkali stability.

[0046] Preferably, after disinfection with a caustic alkali, the modified polymer film has a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption amount of 55 μg / cm³. 2 The following applies:

[0047] Preferably, the modified polymer membrane has autoclavability.

[0048] Preferably, after autoclaving, the modified polymer membrane has a wetting time of 5 seconds or less, changes in water flux and bubble point values ​​of 20% or less, and a protein adsorption capacity of 55 μg / cm³. 2 The following applies:

[0049] Preferably, the modified polymer membrane has gamma-ray sterilization stability.

[0050] Preferably, after gamma ray sterilization, the modified polymer membrane has a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption capacity of 55 μg / cm³. 2 The following applies:

[0051] Preferably, the modified polymer membrane is applied to a filtration device.

[0052] According to yet another aspect of the present invention, a filtration device is provided, which includes a housing having a fluid inlet and a fluid outlet, and having the aforementioned modified polymer membrane provided inside. [Effects of the Invention]

[0053] The present invention provides a method for modifying polymer membranes, which involves modifying the polymer membrane using two types of crosslinking agents to form a 3D network on the surface and body of the polymer membrane, thereby obtaining a modified polymer membrane. The modified polymer membrane of the present invention has low protein adsorption, caustic alkali stability, autoclavability stability, and gamma ray sterilization stability, while retaining overall mechanical properties that can meet the requirements for foldability for filter manufacturing. The method for modifying polymer membranes and the modified polymer membrane of the present invention have high practical value and beneficial effects. [Modes for carrying out the invention]

[0054] To further illustrate the present invention, preferred embodiments are described below. Those skilled in the art will understand that the following descriptions are illustrative and not limiting, and should not be used to restrict the scope of protection of the present invention.

[0055] The polymer film described in the present invention is produced from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer.

[0056] The method for modifying a polymer membrane described in the present invention is: A step of pre-wetting the polymer film with a crosslinking agent solution containing a first crosslinking agent and a second crosslinking agent, The steps include: irradiating a pre-moistened polymer film to induce a crosslinking reaction between the first crosslinking agent and the second crosslinking agent in the polymer film, or to induce a crosslinking reaction between the first crosslinking agent, the second crosslinking agent and the polymer film; The process includes the steps of washing away the polymer film after the crosslinking reaction, drying it, and obtaining a modified polymer film.

[0057] If the polymer membrane is a hydrophilic membrane, the crosslinking agent solution comprises the first crosslinking agent and the second crosslinking agent, specifically obtained by dissolving the first crosslinking agent and the second crosslinking agent in an aqueous solution. If the polymer membrane is a hydrophobic membrane, the crosslinking agent solution comprises the first crosslinking agent, the second crosslinking agent, and an aqueous solution of low molecular weight alcohol, specifically obtained by dissolving the first crosslinking agent and the second crosslinking agent in the aqueous solution of low molecular weight alcohol. The function of the aqueous solution of low molecular weight alcohol is to help wet the hydrophobic membrane.

[0058] After irradiating a pre-moistened polymer film, some polymer films (e.g., PVDF or nylon films) participate in the crosslinking reaction, specifically inducing a crosslinking reaction between the first crosslinking agent, the second crosslinking agent, and the polymer film. Specifically, the polymer film, the first crosslinking agent, and the second crosslinking agent each generate free radicals upon irradiation, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film. Some polymer films do not participate in the crosslinking reaction (e.g., PES films do not participate in the reaction at room temperature and low doses), specifically inducing a crosslinking reaction between the first and second crosslinking agents in the polymer film. Specifically, the first and second crosslinking agents each generate free radicals upon irradiation, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0059] To ensure the hydrophilicity of the modified polymer membrane, hydrophilic organic compounds may be selected as the first and second crosslinking agents. For ease of comparison, the polymer membranes used in the examples and comparative examples of the present invention are hydrophobic polyethersulfone membranes (PES) that do not participate in the crosslinking reaction at room temperature and low doses. When modifying a hydrophilic polymer membrane or a polymer membrane that participates in the crosslinking reaction, although there is a distinction between the composition of the crosslinking agent solution and the crosslinking reaction as described above, the experimental results are similar.

[0060] The polyethersulfone film (PES) is a hydrophobic polyethersulfone film (PES) manufactured in the laboratory using the formulation disclosed in patent application US2023 / 0017950A1. The casting solution for the hydrophobic polyethersulfone film (PES) consists of 15-20 wt% PES resin, N-methyl-2-pyrrolidone (NMP) as a solvent, and triethylene glycol (TEG) as a non-solvent. First, a film is formed on a heated glass plate, then the formed film is exposed to air of appropriate humidity, and finally, it is immersed in a forming bath consisting mainly of water to perform final solvent-non-solvent exchange extraction and final film shaping to obtain a polymer film. The polymer film is a microporous film, and the polymer film is a polyethersulfone film. After drying the polymer membrane, the polymer membrane is moistened with isopropanol (IPA) of 99.5% or more, and a membrane sample of the polymer membrane is tested using a pore size analyzer (Innova CFP-200A type), and it is found that the bubble point pressure of the membrane sample is 15-30 psi and the average thickness is 130 ± 20 μm. The examples and comparative examples of the present invention modify the polymer membrane, and the performance of the modified polymer membrane is tested by performing a water flux test, a bubble point test, a protein adsorption test, and stability tests for disinfection with caustic alkali, autoclaving, and gamma ray sterilization.

[0061] The present invention modifies a polymer film by irradiating the pre-wet polymer film with at least one of electron beams, X-rays, ultraviolet rays, gamma rays, plasma, and thermal energy. For ease of comparison, both the examples and comparative examples of the present invention modify the polymer film using electron beams with doses of 10 to 50 kGy. Specifically, both the examples and comparative examples of the present invention irradiate the polymer film with a 30 kGy electron beam, and the experimental results are similar when the polymer film is irradiated with electron beams of other doses. The specific steps are as follows.

[0062] The polymer film is cut into pieces of approximately 7 inches x 7 inches or larger and then stored in a 2 mil polyethylene (PE) bag. The polymer film is pre-wetted with a crosslinking agent solution, which comprises a first crosslinking agent, a second crosslinking agent, and an aqueous solution of low molecular weight alcohol, specifically prepared by dissolving a certain amount of the first and second crosslinking agents in a 10 wt% aqueous solution of low molecular weight alcohol, specifically the aqueous solution of low molecular weight alcohol being IPA, and is used to help wet the hydrophobic polymer film. Specifically, the first crosslinking agent is a hydrophilic organic compound containing two or more first active reactive groups, specifically the first active reactive group being a bisacrylamide group, such as methylenebisacrylamide or ethylidenebisacrylamide. The second crosslinking agent is a hydrophilic organic compound containing two or more second active reactive groups, the second active reactive group being an acrylate group. Specifically, the second crosslinking agent comprises at least two acrylate bonds, and the second crosslinking agent may be selected from ethoxylated trimethylolpropane triacrylate or a propoxylated trimethylolpropane triacrylate compound. After the polymer film is completely immersed in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0063] A pre-moistened polymer film is irradiated with an electron beam to induce a crosslinking reaction, forming a 3D network on the surface and body of the polymer film. Specifically, under nitrogen gas, the polymer film is exposed to an electron beam with a constant acceleration voltage and dose at a linear velocity of 15 to 30 inches / min, and the first and second crosslinking agents are irradiated, generating free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0064] The polymer film irradiated with an electron beam is removed from the PE bag and washed with IPA (isopropanol). After washing is complete, the IPA is replaced with pure water, and the washed polymer film is then air-dried overnight to obtain a modified polymer film.

[0065] Performance tests were conducted on the modified polymer film as described below.

[0066] 1. Performance testing of modified polymer membranes Performance testing of the modified polymer membrane includes tests for wetting time, water flux, bubble points, and protein adsorption. Specifically, the modified polymer membrane is first rinsed in IPA, then thoroughly rinsed in deionized water, and finally air-dried overnight to test its performance. The test method is as follows:

[0067] 1. Wetting time The wetting time is determined using the test method described in patent application US2023 / 0017950A1, which includes the step of placing a droplet (30-60 μL) of a 10% NaCl aqueous solution on the surface of the modified polymer film and recording the time (in seconds) required for the modified polymer film to wet. Specifically, the liquid can penetrate the modified polymer film through the wetted portion, and the wetted portion of the modified polymer film becomes transparent compared to the unwetted portion. The time required for the wetted portion of the surface of the modified polymer film to become transparent is recorded, and generally, if the wetting time is 5 seconds or less, the film is considered to be wetting immediately.

[0068] 2. Water flux The modified polymer membrane was cut into 47 mm round slices, moistened with water, and placed in a filter holder. The filter holder was connected to a pressurized water tank, and water passed through the modified polymer membrane with a pressure difference of 14.5 pounds / square inch. After reaching equilibrium, the flux of water passing through the modified polymer membrane was measured in liters / square meter / hour / (pounds / square inch), i.e., LMH / psi.

[0069] 3. Bubble Point Test The modified polymer membrane was cut into round flakes with a diameter of 47 mm. Using IPA as a wetting agent, a bubble point test was carried out using a pore size analyzer (Innova CFP-200A type) in accordance with ASTM F316 standard. Through the bubble point test, the pore size of the modified polymer membrane can be measured, and the bubble point value is inversely proportional to the pore size.

[0070] 4. Protein adsorption test (refer to Patent EP3586948A1) The protein adsorption amount of the modified polymer membrane was measured by a static immersion test using IgG protein. Model protein IgG (human IgG, ≥99%, Sigma-Aldrich Co.) in phosphate buffered saline (PBS, SigmaAldrich Co., LLC) at pH 7.4 was used. A protein solution with a concentration of 1 mg / ml was prepared. The modified polymer membrane was cut into a plurality of round flakes with a diameter of 13 mm (at least 3 per membrane group). One such round flake sample was placed in a 5 ml PTFE test tube, and 2 ml of the protein solution was added using a calibrated micropipette. In addition, three test tubes without round flake samples inside were used as negative controls. At ambient temperature, all test tubes were placed on a rotating shaker stand with a rotation speed of 20 rpm for 2 hours, and then the test tubes were transferred to clean UV cuvettes, and an absorbance test was carried out at 280 nm using an ultraviolet spectrophotometer (Thermo Fisher, Evolution One). A calibration curve was constructed using IgG solutions with concentrations of 0.25 mg / ml, 0.5 mg / ml, 0.75 mg / ml, and 1.0 mg / ml, and the amount of IgG adsorbed on the surface was measured. Based on the calibration curve, the amount of protein adsorbed on each round flake was calculated using the following formula.

[0071] Protein adsorption amount (μg / cm 2 ) = Absorbance サンプル / Absorbance 陰性対照 × IgG solution concentration × Protein solution volume / Flake surface area

[0072] II. Performance test of the modified polymer membrane after disinfection or sterilization After modifying the polymer film by electron beam irradiation, the modified polymer film is disinfected or sterilized, specifically including the following:

[0073] 1. Disinfection with caustic alkali: Immerse in a 1N (normality) sodium hydroxide (NaOH, pH=14) aqueous solution for ≥72 hours at ambient temperature.

[0074] 2. Auto sterilization: Auto sterilize at 126°C for 1 hour.

[0075] 3. Gamma ray sterilization: Sterilization is performed by irradiating with gamma rays at a dose of 45 kGy or higher.

[0076] Using the aforementioned test methods, performance tests including those for wetting time, water flux, bubble points, and protein adsorption can be performed on the modified polymer film after disinfection with caustic alkali, autoclaving, and gamma ray sterilization.

[0077] (Comparative Example 1) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.1 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0078] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0079] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0080] The modified polymer membrane is cut to a specific size to obtain modified membrane samples for testing, and these membrane samples are numbered Comparative Example 1.1 and Comparative Example 1.3.

[0081] (Comparative Example 2) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.1 wt% MBAM and 4 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0082] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0083] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0084] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered Comparative Example 2.1 and Comparative Example 2.3.

[0085] (Comparative Example 3) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.2 wt% MBAM and 3.5 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0086] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0087] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0088] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered Comparative Example 3.1 and Comparative Example 3.3.

[0089] (Example 1) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.3 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0090] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0091] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0092] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 1.1, Example 1.5, and Example 1.6.

[0093] (Example 2) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.3 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0094] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0095] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0096] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 2.1, Example 2.2, Example 2.5, and Example 2.6.

[0097] (Example 3) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.3 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0098] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0099] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0100] The modified polymer membrane is cut to a specific size to obtain a modified membrane sample for testing, and the membrane sample is numbered as Example 3.1.

[0101] (Example 4) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.4 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0102] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0103] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0104] The modified polymer film is cut to a specific size to obtain a modified film sample for testing, and the modified film sample is numbered as Example 4.1.

[0105] (Example 5) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.4 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0106] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0107] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0108] The modified polymer film is cut to a specific size to obtain a modified film sample for testing, and the modified film sample is numbered as Example 5.1.

[0109] (Example 6) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.4 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0110] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0111] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0112] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 6.1, Example 6.2, Example 6.3, Example 6.4, and Example 6.7.

[0113] (Example 7) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.6 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0114] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0115] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0116] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 7.1, Example 7.3, and Example 7.4.

[0117] (Example 8) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.6 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0118] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0119] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0120] The modified polymer membrane is cut to a specific size to obtain modified membrane samples for testing, and these modified membrane samples are numbered as Example 8.1, Example 8.3, and Example 8.4.

[0121] (Example 9) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.6 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0122] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0123] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0124] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 9.1 and Example 9.7.

[0125] (Example 10) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% MBAM and 1 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0126] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0127] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0128] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 10.1 and Example 10.7.

[0129] (Example 11) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% MBAM and 2 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0130] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0131] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0132] The modified polymer film is cut to a specific size to obtain a modified film sample for testing, and the modified film sample is numbered as Example 11.1.

[0133] (Example 12) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% MBAM and 3 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0134] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0135] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0136] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered as Example 12.1, Example 12.3, Example 12.4, Example 12.5, and Example 12.7.

[0137] (Comparative Example 4) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% MBAM and 4 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0138] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0139] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0140] The modified polymer membrane is cut to a specific size to obtain modified membrane samples for testing, and these modified membrane samples are numbered as Comparative Example 4.1, Comparative Example 4.2, Comparative Example 4.3, and Comparative Example 4.4.

[0141] (Comparative Example 5) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 0.8 wt% MBAM and 6 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0142] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0143] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0144] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered Comparative Example 5.1, Comparative Example 5.3, and Comparative Example 5.4.

[0145] (Comparative Example 6) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent, a second crosslinking agent, and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 1.2 wt% MBAM and 9 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0146] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction between the first and second crosslinking agents in the polymer film is induced. Specifically, upon irradiation, the first and second crosslinking agents each generate free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinked network on the surface and body of the polymer film.

[0147] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0148] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered Comparative Example 6.1 and Comparative Example 6.2.

[0149] (Comparative Example 7) The polymer film is pre-wetted with a crosslinking agent solution containing a first crosslinking agent and an aqueous solution of a low molecular weight alcohol. The first crosslinking agent is N,N-methylenebisacrylamide (MBAM), and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 1.2 wt% MBAM in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0150] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction of the first crosslinking agent in the polymer film is induced. Specifically, upon irradiation, the first crosslinking agent generates free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinking network on the surface and body of the polymer film.

[0151] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0152] The modified polymer film is cut to a specific size to obtain a modified film sample for testing, and this modified film sample is numbered as Comparative Example 7.1.

[0153] (Comparative Example 8) The polymer film is pre-wetted with a crosslinking agent solution containing a second crosslinking agent and an aqueous solution of a low molecular weight alcohol, wherein the second crosslinking agent is ethoxylated trimethylolpropane triacrylate (ETMPTA) and the aqueous solution of the low molecular weight alcohol is isopropanol (IPA). Specifically, the crosslinking agent solution is prepared by dissolving 4 wt% ETMPTA in 10 wt% IPA. Specifically, after completely immersing the polymer film in the crosslinking agent solution, excess crosslinking agent solution on the polymer film is removed using a rubber roller.

[0154] By irradiating a pre-moistened polymer film with an electron beam of 30 kGy, a crosslinking reaction of the second crosslinking agent in the polymer film is induced. Specifically, upon irradiation, the second crosslinking agent generates free radicals, and the crosslinking reaction occurs between the same or different free radicals, forming a 3D crosslinking network on the surface and body of the polymer film.

[0155] The polymer film after the crosslinking reaction is washed away and dried to obtain a modified polymer film. An alcohol solution is used for washing, and after washing is complete, the alcohol solution is replaced with distilled water to obtain the modified polymer film.

[0156] The modified polymer film is cut to a specific size to obtain modified film samples for testing, and these modified film samples are numbered Comparative Example 8.1 and Comparative Example 8.3.

[0157] (Example 13) This example involves conducting wettability tests on the modified film samples described in Examples 1-12 and Comparative Examples 1-8, and studying the effect of different mixing ratios of the first and second crosslinking agents on the wettability of the modified film samples. The test results are shown in Table 1.

[0158] Table 1 [Table 1]

[0159] According to the test results in Table 1, the wetting time for Examples 1.1 to 12.1 and Comparative Examples 1.1 to 8.1 was all less than 5 seconds, indicating that immediate wetting can be achieved in all cases.

[0160] (Example 14) This example involves performing water flux tests and bubble point tests on the modified film samples described in Example 2, Example 6, Comparative Example 4, and Comparative Example 6. The test results are shown in Table 2.

[0161] Table 2 [Table 2]

[0162] According to the test results in Table 2, when relatively low concentrations of the first and second crosslinking agents (Examples 2.2 and 6.2) were used, there was no significant effect on the water flux and bubble points of the polymer membrane before and after modification. However, when high concentrations of the first and second crosslinking agents (Comparative Examples 4.2 and 6.2) were used, some of the membrane pores of the polymer membrane were blocked, and the water flux decreased significantly.

[0163] (Example 15) This example performs a caustic alkali stability test on the modified film samples described in Examples 6, 7, 8, 12, Comparative Examples 1-5, and Comparative Example 8. Specifically, the wetting time and water flux after disinfection with caustic alkali of the modified film sample are compared with the wetting time and water flux before disinfection with caustic alkali. If the wetting time of the modified film sample after disinfection is still less than 5 seconds and the change in water flux is less than 20%, it is indicated that the modified polymer film has caustic alkali stability. Specifically, the disinfection step with caustic alkali involved immersing the modified film sample in a 1N NaOH solution for more than 72 hours, thoroughly rinsing the modified film sample with distilled water, air-drying it overnight, and baking the modified film sample in an oven at 135°C for 2 hours before testing. The test results for the wetting time of the modified film sample are shown in Table 3, and the test results for the water flux are shown in Table 4.

[0164] Table 3 [Table 3]

[0165] Table 4 [Table 4]

[0166] According to the test results in Table 3, modified film samples treated with low concentrations of MBAM or without MBAM (Comparative Examples 1.3-3.3 and 8.3) showed a significant decrease in wettability after immersion in NaOH. In contrast, the modified film samples described in Examples 6.3-8.3 and 12.3 retained their wettability after disinfection with caustic alkali.

[0167] In the prior art, as mentioned by Charkoudian in US7648034, immersion of a Durapore® membrane in a pH=13 sodium hydroxide solution for just 2 hours resulted in a 75% decrease in the membrane's water flux. However, as shown in the test results in Table 4, after disinfection with caustic alkali, the water flux of the modified membrane samples described in Examples 6.4-8.4, Example 12.4, and Comparative Examples 4.4-5.4 remained largely unchanged, demonstrating the importance of MBAM in the modification process and highlighting the importance of MBAM concentration in ensuring the caustic alkali stability of modified membrane samples in harsh environments with high pH levels (pH 14).

[0168] Based on the above, the test results of this embodiment indicate that the MBAM concentration must be greater than 0.2 wt% in order to ensure the caustic alkali stability of the modified film sample.

[0169] (Example 16) This example performs autoclaving stability tests on the modified film samples described in Examples 1, 2, and 12. Specifically, before the test, the moistened modified film samples were first air-dried, and then dried at 100°C for 2 hours. Specifically, the moistening time, water flux, and bubble point value of the modified film sample after autoclaving were compared with those before sterilization. If the moistening time of the modified film sample after sterilization is less than 5 seconds, the change in water flux is less than 20%, and the change in bubble point value is less than 20%, then the modified film sample is considered to have autoclaving stability. The test results are shown in Table 5.

[0170] Table 5 [Table 5]

[0171] According to the test results in Table 5, the wetting time, water flux, and bubble point values ​​of the modified film sample after autoclaving did not change significantly compared to the modified film sample before autoclaving. In other words, the modified film sample has autoclaving stability.

[0172] (Example 17) In this example, the modified film samples described in Examples 1 and 2 were subjected to gamma-ray sterilization stability tests. Specifically, the modified film samples were sterilized by irradiating them with gamma rays of ≥45 kGy. Specifically, before the test, the moistened modified film samples were first air-dried, and then dried at 100°C for 2 hours. Specifically, the moistening time, water flux, and bubble point value of the modified film sample after gamma-ray sterilization were compared with those before sterilization. If the moistening time of the modified film sample after sterilization was less than 5 seconds, the change in water flux was less than 20%, and the change in bubble point value was less than 20%, then the modified polymer film was considered to have gamma-ray sterilization stability. The test results are shown in Table 6.

[0173] Table 6 [Table 6]

[0174] According to the test results in Table 6, when the modified film sample was sterilized by exposure to gamma rays at a dose of 49 kGy, the wetting time, water flux, and bubble point values ​​of the modified film sample after gamma ray sterilization did not change significantly compared to the modified film sample before gamma ray sterilization. In other words, the modified film sample has gamma ray sterilization stability.

[0175] (Example 18) This example performs protein adsorption tests on the modified membrane samples described in Examples 10, 12, 6, and 9. Three modified membrane samples from each group were subjected to the corresponding sterilization treatment, and the tests were performed on the modified membrane samples from each group. After sterilizing the modified membrane samples, they were first washed with IPA, then thoroughly washed with DI water, and air-dried overnight before testing.

[0176] In this embodiment, the modified film sample was immersed in a 1N NaOH aqueous solution (pH=14) for more than 72 hours, disinfected with caustic alkali, sterilized by autoclaving at 126°C for 1 hour, and sterilized with gamma rays at a dose of 45 kGy or more.

[0177] In this example, to facilitate comparison, the protein adsorption capacity of commercially available Durapore® PVDF membranes, known for their low protein adsorption, and the protein adsorption capacity of unmodified hydrophobic PES membranes were used as baselines for testing. The average protein adsorption capacity of Durapore® PVDF membranes was 36.0 ± 10.2 μg / cm³. 2 The average protein adsorption capacity of an unmodified hydrophobic PES membrane was 140.6 ± 11.8 μg / cm³. 2 The results are shown in Table 7.

[0178] Table 7 [Table 7]

[0179] The test results in Table 7 show the following:

[0180] (1) The modified membrane sample had a protein adsorption capacity similar to that of the Durapore® membrane, but significantly lower than that of the unmodified hydrophobic membrane, indicating that the modification effectively reduced protein adsorption.

[0181] (2) After disinfection with caustic alkali, autoclaving, and gamma ray sterilization, the protein adsorption properties of the modified membrane sample did not change significantly, indicating that the protein adsorption of the modified membrane sample is stable with caustic alkali, autoclaving, and gamma ray sterilization.

[0182] (3) The modified membrane sample has a protein adsorption capacity similar to that of the Durapore® membrane. However, as Charkoudian mentions in US7648034, after immersing the Durapore® membrane in a pH=13 sodium hydroxide solution for just 2 hours, the water flux of the membrane decreases by 75%, meaning that the Durapore® membrane does not have caustic alkali stability. According to the test results of Example 15, the modified membrane sample described in this example has caustic alkali stability, and therefore the performance of the modified membrane sample described in this example is superior to that of the Durapore® membrane.

[0183] (Example 19) This embodiment provides the use of a modified polymer membrane as described in any of Examples 1 to 12. In this embodiment, the modified polymer membrane is applied to a filtration device. The filtration device includes a stack filter, a cartridge filter, a capsule filter, and a spiral filter.

[0184] The modified polymer membrane may be a flat membrane or a hollow fiber membrane.

[0185] (Example 20) This embodiment provides a filtration device. The filtration device includes a housing having a fluid inlet and a fluid outlet, and having a modified polymer membrane according to any one of Examples 1 to 12 provided inside.

[0186] In this embodiment, the filtration device includes a stack filter, a cartridge filter, a capsule filter, a spiral filter, and the like.

[0187] The modified polymer membrane may be a flat membrane or a hollow fiber membrane.

[0188] The present invention provides a method for modifying polymer membranes, which involves modifying the polymer membrane using two types of crosslinking agents to form a 3D network on the surface and body of the polymer membrane, thereby obtaining a modified polymer membrane. The modified polymer membrane of the present invention has low protein adsorption, caustic alkali stability, autoclavability stability, and gamma ray sterilization stability, while retaining overall mechanical properties that can meet the requirements for foldability for filter manufacturing. The method for modifying polymer membranes and the modified polymer membrane of the present invention have high practical value and beneficial effects.

[0189] Clearly, the above embodiments of the present invention are merely examples to illustrate the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art can make other different forms of changes or modifications based on the above description, and the embodiments listed herein do not cover all embodiments. Any obvious changes or modifications obtained from the technical means of the present invention fall within the scope of protection of the present invention. All documents referenced in the present invention are cited by reference in this application, just as each document is cited by reference alone.

Claims

1. A step of pre-wetting the polymer film with a crosslinking agent solution containing a first crosslinking agent and a second crosslinking agent, The steps include: irradiating a pre-moistened polymer film to induce a crosslinking reaction between the first crosslinking agent and the second crosslinking agent in the polymer film, or to induce a crosslinking reaction between the first crosslinking agent, the second crosslinking agent and the polymer film; The process includes the steps of washing away the polymer film after the crosslinking reaction, drying it, and obtaining a modified polymer film. Methods for modifying polymer membranes.

2. The polymer film, the first crosslinking agent, and the second crosslinking agent each generate free radicals upon irradiation, and a crosslinking reaction occurs between the free radicals, forming a 3D crosslinked network on the surface and body of the polymer film. A method for modifying a polymer film according to claim 1.

3. The first and second crosslinking agents, upon irradiation, each generate free radicals, and a crosslinking reaction occurs between these free radicals, forming a 3D crosslinked network on the surface and body of the polymer film. A method for modifying a polymer film according to claim 1.

4. The first crosslinking agent is a hydrophilic organic compound containing two or more primary active reactive groups. A method for modifying a polymer film according to claim 1.

5. The first active reactive group is a bisacrylamide group. The method for modifying a polymer film according to claim 4.

6. The first active reactive group is at least one of methylenebisacrylamide and ethylidenebisacrylamide. The method for modifying a polymer film according to claim 5.

7. The second crosslinking agent is a hydrophilic organic compound containing two or more secondary active reactive groups. A method for modifying a polymer film according to claim 1.

8. The second active reactive group is an acrylate group. The method for modifying a polymer film according to claim 7.

9. The second active reactive group comprises at least two acrylate bonds. The method for modifying a polymer film according to claim 8.

10. The concentration of the first crosslinking agent is 0.3 to 0.8 wt%, and the concentration of the second crosslinking agent is 1.0 to 3.0 wt%. A method for modifying a polymer film according to claim 1.

11. Irradiating a pre-moistened polymer film involves irradiating the pre-moistened polymer film with at least one of the following: electron beams, X-rays, ultraviolet rays, gamma rays, plasma, and thermal energy. A method for modifying a polymer film according to claim 1.

12. The dose of the electron beam is 10 to 50 kGy. A method for modifying a polymer film according to claim 11.

13. An alcohol solution is used for rinsing. A method for modifying a polymer film according to claim 1.

14. After rinsing is complete, replace the alcohol solution with distilled water. A method for modifying a polymer film according to claim 13.

15. If the polymer film is a hydrophobic film, the crosslinking agent solution further comprises an aqueous solution of a low molecular weight alcohol. A method for modifying a polymer film according to claim 1.

16. The polymer film is a microporous film. A method for modifying a polymer film according to claim 1.

17. The polymer film is manufactured from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer. A method for modifying a polymer film according to claim 16.

18. The protein adsorption capacity of the modified polymer membrane is 55 μg / cm³. ２ The following is: A method for modifying a polymer film according to claim 1.

19. The wetting time of the modified polymer film is 5 seconds or less. A method for modifying a polymer film according to claim 1.

20. The modified polymer membrane exhibits a change of 20% or less in both water flux and bubble point values ​​compared to the polymer membrane. A method for modifying a polymer film according to claim 1.

21. The modified polymer film has caustic alkali stability. A method for modifying a polymer film according to claim 1.

22. The modified polymer membrane, after disinfection with caustic alkali, has a wetting time of 5 seconds or less, changes in water flux and bubble point values ​​of 20% or less, and a protein adsorption capacity of 55 μg / cm³. ２ The following is: The method for modifying a polymer film according to claim 21.

23. The modified polymer membrane has high-pressure sterilization stability. A method for modifying a polymer film according to claim 1.

24. After autoclaving, the modified polymer membrane exhibits a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption capacity of 55 μg / cm³. ２ The following is: The method for modifying a polymer film according to claim 23.

25. The modified polymer membrane has gamma-ray sterilization stability. A method for modifying a polymer film according to claim 1.

26. After gamma ray sterilization, the modified polymer membrane exhibits a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption capacity of 55 μg / cm³. ２ The following is: The method for modifying a polymer film according to claim 25.

27. A polymer film obtained by modifying a polymer film using the polymer film modification method described in any one of claims 1 to 15. Modified polymer membrane.

28. The polymer film is a microporous film. The modified polymer film according to claim 27.

29. The polymer film is manufactured from one or more copolymers or mixtures of polysulfone, polyethersulfone, polyarylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate, cellulose nitrate, polypropylene, polyethylene, polyolefin polymer, polyamide, polyimide, acrylic polymer, and methacrylic polymer. The modified polymer membrane according to claim 28.

30. The protein adsorption capacity of the modified polymer membrane is 55 μg / cm³. ２ The following is: The modified polymer film according to claim 27.

31. The wetting time of the modified polymer film is 5 seconds or less. The modified polymer film according to claim 27.

32. The modified polymer membrane exhibits a change of 20% or less in both water flux and bubble point values ​​compared to the original polymer membrane. The modified polymer film according to claim 27.

33. The modified polymer film has caustic alkali stability. The modified polymer film according to claim 27.

34. The modified polymer membrane, after disinfection with caustic alkali, has a wetting time of 5 seconds or less, changes in water flux and bubble point values ​​of 20% or less, and a protein adsorption capacity of 55 μg / cm³. ２ The following is: The modified polymer film according to claim 33.

35. The modified polymer membrane has high-pressure sterilization stability. The modified polymer film according to claim 27.

36. After autoclaving, the modified polymer membrane exhibits a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption capacity of 55 μg / cm³. ２ The following is: The modified polymer film according to claim 35.

37. The modified polymer membrane has gamma-ray sterilization stability. The modified polymer film according to claim 27.

38. After gamma ray sterilization, the modified polymer membrane exhibits a wetting time of 5 seconds or less, a change of 20% or less in both water flux and bubble point values, and a protein adsorption capacity of 55 μg / cm³. ２ The following is: The modified polymer film according to claim 37.

39. The modified polymer membrane is applied to a filtration device. The modified polymer film according to claim 27.

40. A housing having a fluid inlet and a fluid outlet, and having a modified polymer film according to claim 27 provided inside, Filtration device.

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