Composite diaphragm material for electrolysis and its preparation process

Abstract

The application discloses a kind of composite diaphragm material for electrolysis and preparation process thereof, belong to diaphragm material technical field.The composite diaphragm material is made of two filter membranes A and B, the A filter membrane includes the following weight parts of raw materials: modified vinyl chloride-acrylonitrile copolymer 12-18 parts, N,N-dimethylformamide 65-70 parts, dimethyl sulfoxide 15-20 parts, polyvinylpyrrolidone 1-2 parts;The B filter membrane includes the following weight parts of raw materials: modified vinyl chloride-acrylonitrile copolymer 10-15 parts, N,N-dimethylformamide 4-6 parts, modified graphene oxide 60-65 parts, dimethyl sulfoxide 15-20 parts, polyvinylpyrrolidone 1-2 parts.The electrolysis diaphragm material prepared by the application has good water absorption and low surface resistance, which can reduce the production cost of metal nickel.

Description

Technical Field

[0001] This invention relates to the field of membrane material technology, specifically to a composite membrane material for electrolysis and its preparation process. Background Technology

[0002] In the production practice of electrolytic extraction and refining of metallic nickel, electrode diaphragms play a crucial role. They are primarily used to separate the cathode and anode in the electrolytic cell, forming independent cathode and anode chambers. This requires them to possess good chemical stability and sufficient mechanical strength. However, traditional diaphragm materials (such as natural and synthetic fibers) have limitations in terms of chemical stability and mechanical strength, making it difficult to meet the requirements of modern electrolysis technology. Currently used diaphragms use polyester filter cloth as the base fabric, which can withstand strong acid and alkali environments or even closed, high-pressure, and high-temperature strong acid and alkali environments without corrosion. However, filter cloth is an insulating material, consuming a large current during electrolysis, resulting in high production costs. Furthermore, the hydrophobicity of polyester filter cloth is detrimental to electrolyte wetting and ion transport.

[0003] Chinese invention patent CN116601334A discloses a substrate for an alkaline water electrolysis membrane and an alkaline water electrolysis membrane. The invention comprises a substrate for an alkaline water electrolysis membrane and an alkaline water electrolysis membrane containing the substrate and a porous membrane made of a polymer resin. The substrate is characterized by being composed of a nonwoven fabric containing polyphenylene sulfide fibers with an irregular cross-section, and has a density of 0.30 g / cm³. 3 Above and 0.80 g / cm 3 The following have a longitudinal and transverse elongation of more than 10% and less than 35%, but their resistance is relatively high. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a composite membrane material for electrolysis and its preparation process.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A composite membrane material for electrolysis is composed of two filter membranes, A and B. The filter membrane A comprises the following raw materials in parts by weight: 12-18 parts of modified vinyl chloride-acrylonitrile copolymer, 65-70 parts of N,N-dimethylformamide, 15-20 parts of dimethyl sulfoxide, and 1-2 parts of polyvinylpyrrolidone.

[0007] The B filter membrane comprises the following raw materials in parts by weight: 10-15 parts of modified vinyl chloride-acrylonitrile copolymer, 4-6 parts of N,N-dimethylformamide, 60-65 parts of modified graphene oxide, 15-20 parts of dimethyl sulfoxide, and 1-2 parts of polyvinylpyrrolidone.

[0008] The modified vinyl chloride-acrylonitrile copolymer is prepared by the following method:

[0009] S1: Polyethylene glycol monomethyl ether reacts with trimellitic anhydride to form a monoester compound; the reaction equation is shown below.

[0010]

[0011] S2: The monoester compound reacts with (4-vinylphenyl)methanol to form a triester compound; the reaction equation is shown below.

[0012]

[0013] The meaning is as follows:

[0014] S3: Vinyl chloride, acrylonitrile and triester compound react to form modified vinyl chloride-acrylonitrile copolymer. In this reaction, vinyl chloride, acrylonitrile and triester compound undergo polymerization to form modified vinyl chloride-acrylonitrile copolymer.

[0015] In step S1, the mass ratio of polyethylene glycol monomethyl ether to trimellitic anhydride is (3.5-3.8):1.

[0016] In step S2, the mass ratio of the monoester compound to (4-vinylphenyl)methanol is (3.3-3.5):1.

[0017] In step S3, the mass ratio of acrylonitrile, vinyl chloride and triglyceride compound is 5:6:(2-3).

[0018] The modified graphene is prepared by the following method:

[0019] N1: Graphene oxide reacts with glycine to form carboxylated graphene; in this reaction, the epoxy groups on the surface of graphene oxide react with the amino groups of glycine to form β-amino alcohol functional groups.

[0020] N2: Carboxylated graphene reacts with p-aminophenyltrimethoxysilane to generate aminographene; in this reaction, the hydroxyl groups on the surface of graphene oxide undergo a condensation reaction with the silanyl groups of p-aminophenyltrimethoxysilane.

[0021] N3: Aminographene reacts with aniline to generate polyaniline graphene; in this reaction, the polyaniline structure is synthesized starting from the amino terminus of the grafted p-aminophenyltrimethoxysilane.

[0022] N4: Polyaniline graphene reacts with polyvinyl alcohol to generate modified graphene; in this reaction, the carboxyl groups in polyaniline graphene undergo esterification with the hydroxyl groups of polyvinyl alcohol.

[0023] In step N1, the mass ratio of graphene oxide to glycine is 5:2.

[0024] In step N2, the mass ratio of the carboxylated graphene to p-aminophenyltrimethoxysilane is 3:1.

[0025] In step N3, the mass ratio of the amino-based graphene to aniline is 3:2.

[0026] In step N4, the mass ratio of polyaniline graphene to polyvinyl alcohol is 10:3.

[0027] A process for preparing a composite membrane material for electrolysis, characterized by comprising the following steps:

[0028] (1) Add the raw materials of filter membrane A and filter membrane B into two reaction vessels respectively, heat to 50-60℃, stir and dissolve to prepare adhesive solution A and adhesive solution B;

[0029] (2) The polyester filter cloth is immersed in adhesive solution A and adhesive solution B respectively, squeezed into a film, and then soaked in a cold water pool, soaked in a hot water pool, and dried to obtain filter membrane A and filter membrane B.

[0030] (3) Cut, align and sew the A and B filter membranes to obtain the composite membrane material.

[0031] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0032] (1) The modified vinyl chloride-acrylonitrile copolymer prepared in this invention improves the hydrophilicity of the membrane and reduces the surface resistance of the membrane by introducing hydrophilic ethylene glycol monomethyl ether segments and benzene ring structures.

[0033] (2) The modified graphene prepared by the present invention improves its hydrophilicity and reduces its surface resistance by introducing polyvinyl alcohol segments and polyaniline structure, thereby reducing the production cost of nickel electrolysis. Detailed Implementation

[0034] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0035] Example 1: Preparation of modified vinyl chloride-acrylonitrile copolymer

[0036] S1: Under nitrogen protection, 800 ml of anhydrous toluene, 100 g of trimellitic anhydride, 350 g of polyethylene glycol monomethyl ether (MPEG750) and 6 g of sodium propionate were added to a reaction vessel, stirred and mixed, heated to 70 °C, reacted for 6 h, cooled to room temperature, washed three times with deionized water (200 ml each time), dried the organic phase with 30 g of anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 70 °C for 3 h to obtain the monoester compound;

[0037] S2: Under nitrogen protection, 800 ml toluene, 330 mol of monoester compound, 100 g (4-vinylphenyl) methanol, and 10 g p-benzenesulfonic acid were added to a reaction vessel, stirred and mixed, heated to 100 °C, and reacted for 15 h. During the reaction, the water produced was removed through a water separator. The mixture was cooled to room temperature, and the pH was adjusted to 7 using saturated sodium bicarbonate. The mixture was separated into layers, washed three times with deionized water (200 ml each time), and the organic phase was dried with 30 g of anhydrous magnesium sulfate. After filtration, the mixture was distilled under reduced pressure at 70 °C for 3 h to obtain the triester compound.

[0038] S3: Add 500ml DMF, 50g acrylonitrile, and 5g azobisisobutyronitrile to a high-pressure reactor. Evacuate the reactor to a vacuum level of 640mmHg using a vacuum pump. Add 60g vinyl chloride through a closed pipeline by pressure difference. Stir for 30min, raise the temperature to 45℃, and react at 0.8MPa for 6h. Add 150ml of DMF solution containing 20g of triester compound, and continue the reaction for 3h. Cool to room temperature, release the pressure, add 800ml of deionized water, stir to precipitate solid, filter, wash three times with deionized water (200ml each time), and vacuum dry at 60℃ for 24h to obtain modified vinyl chloride-acrylonitrile copolymer.

[0039] Example 2: Preparation of modified vinyl chloride-acrylonitrile copolymer

[0040] S1: Under nitrogen protection, 800 ml of anhydrous toluene, 100 g of trimellitic anhydride, 360 g of polyethylene glycol monomethyl ether (MPEG750) and 6 g of sodium propionate were added to a reaction vessel, stirred and mixed, heated to 80 °C, reacted for 5 h, cooled to room temperature, washed three times with deionized water (300 ml each time), dried the organic phase with 30 g of anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 70 °C for 3 h to obtain the monoester compound;

[0041] S2: Under nitrogen protection, 800 ml of toluene, 340 g of monoester compound, 100 g of (4-vinylphenyl) methanol, and 10 g of p-benzenesulfonic acid were added to a reaction vessel, stirred and mixed, heated to 105 °C, and reacted for 12 h. During the reaction, the water produced was removed through a water separator. The mixture was cooled to room temperature, and the pH was adjusted to 7 using saturated sodium bicarbonate. The mixture was separated into layers, washed three times with deionized water (200 ml each time), and the organic phase was dried with 50 g of anhydrous magnesium sulfate. After filtration, the mixture was distilled under reduced pressure at 70 °C for 3 h to obtain the triester compound.

[0042] S3: Add 500ml DMF, 50g acrylonitrile, and 5g azobisisobutyronitrile to a high-pressure reactor. Evacuate the reactor to a vacuum level of 640mmHg using a vacuum pump. Add 60g vinyl chloride through a closed pipeline by pressure difference. Stir for 30min, raise the temperature to 50℃, and react at 0.8MPa for 5h. Add 150ml of DMF solution containing 25g of triester compound, and continue the reaction for 4h. Cool to room temperature, release the pressure, add 800ml of deionized water, stir to precipitate solid, filter, wash three times with deionized water (200ml each time), and vacuum dry at 60℃ for 24h to obtain modified vinyl chloride-acrylonitrile copolymer.

[0043] Example 3: Preparation of modified vinyl chloride-acrylonitrile copolymer

[0044] S1: Under nitrogen protection, 800 ml of anhydrous toluene, 100 g of trimellitic anhydride, 380 g of polyethylene glycol monomethyl ether (MPEG750) and 6 g of sodium propionate were added to a reaction vessel, stirred and mixed, heated to 85 °C, reacted for 4 h, cooled to room temperature, washed three times with deionized water (300 ml each time), dried the organic phase with 30 g of anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 70 °C for 3 h to obtain the monoester compound;

[0045] S2: Under nitrogen protection, 800 ml of toluene, 350 g of monoester compound, 100 g of (4-vinylphenyl) methanol, and 10 g of p-benzenesulfonic acid were added to a reaction vessel, stirred and mixed, heated to 110 °C, and reacted for 10 h. During the reaction, the water produced was removed through a water separator. The mixture was cooled to room temperature, and the pH was adjusted to 7 using saturated sodium bicarbonate. The mixture was separated into layers, washed three times with deionized water (200 ml each time), and the organic phase was dried with 30 g of anhydrous magnesium sulfate. After filtration, the mixture was distilled under reduced pressure at 70 °C for 3 h to obtain the triester compound.

[0046] S3: Add 500ml DMF, 50g acrylonitrile, and 5g azobisisobutyronitrile to a high-pressure reactor. Evacuate the reactor to a vacuum level of 640mmHg using a vacuum pump. Add 60g vinyl chloride through a closed pipeline by pressure difference. Stir for 30min, raise the temperature to 55℃, and react at 0.8MPa for 4h. Add 150ml of DMF solution containing 30g of triester compound, and continue the reaction for 5h. Cool to room temperature, release the pressure, add 800ml of deionized water, stir to precipitate solid, filter, wash three times with deionized water (200ml each time), and vacuum dry at 60℃ for 24h to obtain modified vinyl chloride-acrylonitrile copolymer.

[0047] Example 4: Preparation of Modified Graphene

[0048] N1: Add 1000ml of deionized water and 50g of graphene oxide to a reaction vessel, sonicate for 1h, add 10g of NaOH and 20g of glycine and stir to mix well, heat to 60℃ and react for 8h, filter, wash three times with deionized water (200ml each time), and vacuum dry at 70℃ for 24h to obtain carboxylated graphene.

[0049] N2: Add 1000ml of deionized water and 60g of carboxylated graphene to a reaction vessel and sonicate for 1h; add 20g of p-aminophenyltrimethoxysilane, then adjust the pH to 4 with acetic acid, heat to 70℃ and react for 4h, cool to room temperature, filter, wash with 200ml of anhydrous ethanol and 200ml of deionized water in sequence, and vacuum dry at 80℃ for 12h to obtain amino-based graphene;

[0050] N3: 800 ml of deionized water and 30 g of amino graphene were placed in a reaction vessel and ultrasonically dispersed for 1 h to prepare a dispersion. 200 ml of 1 M HCl solution and 20 g of aniline were used to prepare an aniline salt solution, which was added to the reaction vessel and cooled to 0 °C. 200 ml of an aqueous solution containing 62 g of ammonium persulfate was added dropwise over 1 h. The reaction was allowed to proceed for 12 h. The mixture was then filtered and washed successively with 200 ml of anhydrous ethanol and 200 ml of deionized water. It was then vacuum dried at 80 °C for 12 h to obtain polyaniline graphene.

[0051] N4: Add 350ml of DMSO (dimethyl sulfoxide) and 10g of polyaniline graphene to a reaction vessel, sonicate for 30min, add 10g of polyvinyl alcohol, 4g of N,N'-dicyclohexylcarboimide and 1.5g of 4-dimethylaminopyridine, stir and mix well, heat to 50℃ and react for 24h, filter, wash three times with methanol (100ml each time), and vacuum dry at 60℃ for 12h to obtain modified graphene.

[0052] Example 5: Preparation of composite membrane material for electrolysis

[0053] (1) Weigh 120g of modified vinyl chloride-acrylonitrile copolymer (prepared in Example 1), 650g of N,N-dimethylformamide, 150g of dimethyl sulfoxide, and 10g of polyvinylpyrrolidone, and add them to the reaction vessel in sequence. Heat to 50°C and stir at 800 rpm for 30 min to prepare adhesive solution A.

[0054] Weigh 100g of modified vinyl chloride-acrylonitrile copolymer (prepared in Example 1), 40g of N,N-dimethylformamide, 600g of modified graphene oxide (prepared in Example 4), 150g of dimethyl sulfoxide, and 10g of polyvinylpyrrolidone, and add them sequentially into a reaction vessel. Heat to 50°C and stir at 800 rpm for 30 minutes to prepare adhesive solution B.

[0055] (2) Inject adhesive A and adhesive B into the laminating tank respectively, turn on the linkage laminating machine, and immerse the polyester filter cloth into the adhesive tank through the guide frame at a speed of 1.5m / min. After being pressed by the extrusion roller (pressure 20MPa) to form a film, immerse it in a 0℃ cold water tank for 15min, then immerse it in a 60℃ hot water tank for 15min, and finally dry it at 80℃ for 5h to obtain filter membrane A and filter membrane B respectively.

[0056] (3) Cut the A and B filter membranes into length × width = 1200mm × 1140mm, with the length of 1200mm being the side edge and the width of 1140mm being the bottom edge; align them and sew them together with a sewing machine: 5 lines on the side edge with a spacing of 1mm; 6 lines on the bottom edge with a spacing of 1mm; fold the top edge at 60mm and sew 2 lines with a spacing of 1mm; thus obtaining the composite membrane material.

[0057] Example 6: Preparation of Composite Membrane Material for Electrolysis

[0058] (1) Weigh 150g of modified vinyl chloride-acrylonitrile copolymer (prepared in Example 2), 680g of N,N-dimethylformamide, 180g of dimethyl sulfoxide, and 15g of polyvinylpyrrolidone, and add them to the reaction vessel in sequence. Heat to 55°C and stir at 800 rpm for 30 min to prepare adhesive solution A.

[0059] Weigh 120g of modified vinyl chloride-acrylonitrile copolymer (prepared in Example 2), 50g of N,N-dimethylformamide, 620g of modified graphene oxide (prepared in Example 4), 180g of dimethyl sulfoxide, and 15g of polyvinylpyrrolidone, and add them sequentially into a reaction vessel. Heat to 55°C and stir at 800 rpm for 30 minutes to prepare adhesive solution B.

[0060] (2) Inject adhesive A and adhesive B into the laminating tank respectively, turn on the linkage laminating machine, and immerse the polyester filter cloth into the adhesive tank through the guide frame at a speed of 1.5m / min. After being pressed by the extrusion roller (pressure 20MPa) to form a film, immerse it in a 0℃ cold water tank for 15min, then immerse it in a 60℃ hot water tank for 15min, and finally dry it at 80℃ for 5h to obtain filter membrane A and filter membrane B respectively.

[0061] (3) Cut the A and B filter membranes into length × width = 1200mm × 1140mm, with the length of 1200mm being the side edge and the width of 1140mm being the bottom edge; align them and sew them together with a sewing machine: 5 lines on the side edge with a spacing of 1mm; 6 lines on the bottom edge with a spacing of 1mm; fold the top edge at 60mm and sew 2 lines with a spacing of 1mm; thus obtaining the composite membrane material.

[0062] Example 7: Preparation of composite membrane material for electrolysis

[0063] (1) Weigh 180g of modified vinyl chloride-acrylonitrile copolymer (prepared in Example 3), 700g of N,N-dimethylformamide, 200g of dimethyl sulfoxide, and 20g of polyvinylpyrrolidone, and add them to the reaction vessel in sequence. Heat to 60°C and stir at 800 rpm for 30 min to prepare adhesive solution A.

[0064] Weigh 150g of modified vinyl chloride-acrylonitrile copolymer (prepared in Example 3), 60g of N,N-dimethylformamide, 650g of modified graphene oxide (prepared in Example 4), 200g of dimethyl sulfoxide, and 20g of polyvinylpyrrolidone, and add them sequentially into a reaction vessel. Heat to 60°C and stir at 800 rpm for 30 minutes to prepare adhesive solution B.

[0065] (2) Inject adhesive A and adhesive B into the laminating tank respectively, turn on the linkage laminating machine, and immerse the polyester filter cloth into the adhesive tank through the guide frame at a speed of 1.5m / min. After being pressed by the extrusion roller (pressure 20MPa) to form a film, immerse it in a 0℃ cold water tank for 15min, then immerse it in a 60℃ hot water tank for 15min, and finally dry it at 80℃ for 5h to obtain filter membrane A and filter membrane B respectively.

[0066] (3) Cut the A and B filter membranes into length × width = 1200mm × 1140mm, with the length of 1200mm being the side edge and the width of 1140mm being the bottom edge; align them and sew them together with a sewing machine: 5 lines on the side edge with a spacing of 1mm; 6 lines on the bottom edge with a spacing of 1mm; fold the top edge at 60mm and sew 2 lines with a spacing of 1mm; thus obtaining the composite membrane material.

[0067] Comparative Example 1

[0068] The raw material composition and preparation process of the composite membrane material for electrolysis are basically the same as those in Example 6. The difference is that the modified vinyl chloride-acrylonitrile copolymer (prepared in Example 2) used in solutions A and B is replaced with an equal mass of the modified vinyl chloride-acrylonitrile copolymer prepared by the following method:

[0069] The preparation method of the modified vinyl chloride-acrylonitrile copolymer is basically the same as that in Example 2, except that the (4-vinylphenyl)methanol in step S2 is replaced with an equal mass of 3-buten-1-ol.

[0070] Comparative Example 2

[0071] The raw material composition and preparation process of the composite membrane material for electrolysis are basically the same as in Example 6, except that the modified vinyl chloride-acrylonitrile copolymer (prepared in Example 2) used in solutions A and B is replaced with an equal mass of the modified vinyl chloride-acrylonitrile copolymer prepared by the following method:

[0072] The preparation method of the modified vinyl chloride-acrylonitrile copolymer is basically the same as that in Example 2, except that the polyethylene glycol monomethyl ether (MPEG750) in step S1 is replaced with an equal mass of polyethylene glycol monomethyl ether (MPEG1500).

[0073] Comparative Example 3

[0074] The raw material composition and preparation process of the composite membrane material for electrolysis are basically the same as in Example 6, except that the modified vinyl chloride-acrylonitrile copolymer (prepared in Example 2) used in solutions A and B is replaced with an equal mass of the modified vinyl chloride-acrylonitrile copolymer prepared by the following method:

[0075] The preparation method of the modified vinyl chloride-acrylonitrile copolymer is basically the same as that in Example 2, except that the polyethylene glycol monomethyl ether (MPEG750) in step S1 is replaced with an equal mass of polyethylene glycol monomethyl ether (MPEG350).

[0076] Comparative Example 4

[0077] The raw material composition and preparation process of the composite membrane material for electrolysis are basically the same as those in Example 6. The difference is that the modified graphene (prepared in Example 4) is replaced with an equal mass of polyaniline graphene (prepared in step N3 of Example 4).

[0078] Comparative Example 5

[0079] The raw material composition and preparation process of the composite membrane material for electrolysis are basically the same as in Example 6, except that the modified graphene (prepared in Example 4) is replaced with an equal mass of modified graphene prepared by the following method:

[0080] N1: Add 1000ml of deionized water and 50g of graphene oxide to a reaction vessel, sonicate for 1h, add 10g of NaOH and 20g of glycine and stir to mix well, heat to 60℃ and react for 8h, filter, wash three times with deionized water (200ml each time), and vacuum dry at 70℃ for 24h to obtain carboxylated graphene.

[0081] N2: Add 350ml DMSO and 10g carboxylated graphene to a reaction vessel, sonicate for 30min, add 10g polyvinyl alcohol, 4g N,N'-dicyclohexylcarboimide and 1.5g 4-dimethylaminopyridine, stir and mix, heat to 50℃ and react for 24h, filter, wash three times with methanol (100ml each time), and vacuum dry at 60℃ for 12h to obtain modified graphene.

[0082] The graphene oxide used in the embodiments and comparative examples of this application is model SE243EW, with a solid content of 42wt%, and is produced by Changzhou Sixth Element Materials Technology Co., Ltd.; polyvinylpyrrolidone is PVP K30; polyester filter cloth is model T6220-5×5 (warp density: 62 threads / inch, weft density: 20 threads / inch, warp yarn 21 / 5, weft yarn 21 / 5; weight per square meter 500g); polyvinyl alcohol is model PVA17-99; and the sewing thread used for sewing is 221-count 5-ply twisted polyester yarn.

[0083] The membrane materials prepared in Examples 5-7 and Comparative Examples 1-5 were tested for water absorption rate and surface resistance. The test results are shown in Table 1.

[0084] The water absorption test was conducted according to GB / T 21655.1-2008: diaphragm A and diaphragm B were cut into 10cm×10cm samples respectively. The total mass m of the two samples was accurately weighed. The two samples were simultaneously placed in 100ml of deionized water at 23℃ and soaked for 5 minutes. After soaking, the samples were removed and hung vertically until no more water dripped from them. The total mass m0 of the two samples was weighed, and the water absorption rate was calculated as (m0-m) / m×100%. The test was repeated 3 times, and the average value was taken.

[0085] The surface resistance test was conducted according to SJ / T 10171.5-1991: diaphragm A and diaphragm B were cut into 40mm × 60mm samples and immersed in a 40wt% sodium hydroxide solution at 23℃ for 4 hours; the 40wt% sodium hydroxide solution was then injected into the resistance test cell; the insert plate was inserted into the resistance test cell, and the resistance value R1 of the solution was measured; the samples of diaphragm A and diaphragm B were aligned and clamped in the insert plate, inserted into the resistance test cell, and the total resistance value R2 of the sample and solution was measured. The surface resistance of the diaphragm was calculated as R = (R2 - R1)·S (where S is the diaphragm area).

[0086] Table 1 Performance Test Data

[0087]

[0088]

[0089] As can be seen from the data in Examples 5, 6 and 7 of Table 1, the electrolytic membrane material prepared by the present invention has good water absorption rate and low surface resistance.

[0090] The composite membrane material for electrolysis prepared in this invention exhibits good water absorption and low surface resistance. This is because: the modified vinyl chloride-acrylonitrile copolymer prepared in this invention contains polyethylene glycol segments, whose hydrophilicity reduces the interfacial tension between the electrolyte and the membrane, promoting rapid electrolyte penetration into the pores; the benzene ring structure in the modified vinyl chloride-acrylonitrile copolymer can form continuous electron channels with graphene through π-π stacking, reducing the electron cross-interfacial migration barrier and thus lowering surface resistance; the cross-linked structure of the modified vinyl chloride-acrylonitrile copolymer can form a uniform coating on the polyester filter cloth surface, improving the mechanical stability and chemical inertness of the membrane and extending its lifespan. In Comparative Example 2, the modified vinyl chloride-acrylonitrile copolymer used has longer polyethylene glycol segments, resulting in increased surface resistance due to steric hindrance; the modified vinyl chloride-acrylonitrile copolymer used in Comparative Example 3 uses shorter polyethylene glycol segments with poorer hydrophilicity.

[0091] The modified graphene prepared in this invention incorporates polyvinyl alcohol segments and polyaniline structures onto graphene oxide, which improves the dispersion performance of graphene in adhesives and prevents increased surface resistance due to agglomeration. The polyvinyl alcohol segments contain numerous hydroxyl groups, providing strong hydrophilicity; they can also form hydrogen bonds with the ethylene glycol monomethyl ether segments in the modified vinyl chloride-acrylonitrile copolymer, contributing to a stable structure and improving the mechanical stability of the membrane. The π-conjugated system of the polyaniline structure forms π-π stacks with the graphene, reducing interfacial charge transfer impedance and achieving efficient carrier migration.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A composite membrane material for electrolysis, composed of a filter membrane A and a filter membrane B, characterized in that, The A filter membrane comprises the following raw materials in parts by weight: 12-18 parts of modified vinyl chloride-acrylonitrile copolymer, 65-70 parts of N,N-dimethylformamide, 15-20 parts of dimethyl sulfoxide, and 1-2 parts of polyvinylpyrrolidone. The B filter membrane comprises the following raw materials in parts by weight: 10-15 parts of modified vinyl chloride-acrylonitrile copolymer, 4-6 parts of N,N-dimethylformamide, 60-65 parts of modified graphene oxide, 15-20 parts of dimethyl sulfoxide, and 1-2 parts of polyvinylpyrrolidone. The modified vinyl chloride-acrylonitrile copolymer is prepared by the following method: S1: Polyethylene glycol monomethyl ether MPEG750 reacts with trimellitic anhydride to form a monoester compound; S2: Monoester compounds react with (4-vinylphenyl)methanol to form triester compounds; S3: Vinyl chloride, acrylonitrile, and a triester compound react to form a modified vinyl chloride-acrylonitrile copolymer; The modified graphene oxide was prepared by the following method: N1: Graphene oxide reacts with glycine to produce carboxylated graphene; N2: Carboxylated graphene reacts with p-aminophenyltrimethoxysilane to generate amino-based graphene; N3: Aminated graphene reacts with aniline to form polyaniline graphene; N4: Polyaniline graphene reacts with polyvinyl alcohol to generate modified graphene oxide.

2. The composite membrane material for electrolysis according to claim 1, characterized in that, In step S1, the mass ratio of polyethylene glycol monomethyl ether to trimellitic anhydride is (3.5-3.8):

1.

3. The composite membrane material for electrolysis according to claim 1, characterized in that, In step S2, the mass ratio of the monoester compound to (4-vinylphenyl)methanol is (3.3-3.5):

1.

4. The composite membrane material for electrolysis according to claim 1, characterized in that, In step S3, the mass ratio of acrylonitrile, vinyl chloride and triester compound is 5:6:(2-3).

5. The composite membrane material for electrolysis according to claim 1, characterized in that, In step N1, the mass ratio of graphene oxide to glycine is 5:

2.

6. The composite membrane material for electrolysis according to claim 1, characterized in that, In step N2, the mass ratio of the carboxylated graphene to p-aminophenyltrimethoxysilane is 3:

1.

7. The composite membrane material for electrolysis according to claim 1, characterized in that, In step N3, the mass ratio of the amino-based graphene to aniline is 3:

2.

8. The composite membrane material for electrolysis according to claim 1, characterized in that, In step N4, the mass ratio of polyaniline graphene to polyvinyl alcohol is 10:

3.

9. A preparation process for a composite membrane material for electrolysis according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Add the raw materials of filter membrane A and filter membrane B to two reaction vessels respectively, heat to 50-60℃, stir and dissolve to prepare adhesive solution A and adhesive solution B; (2) The polyester filter cloth is immersed in adhesive solution A and adhesive solution B respectively, squeezed into a film, and then soaked in a cold water pool, soaked in a hot water pool, and dried to obtain filter membrane A and filter membrane B. (3) Cut, align and sew the A and B filter membranes to obtain the composite membrane material.

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