WO2020237755A1 - Fluorine-containing binder, membrane electrode and preparation methods therefor - Google Patents

Abstract

Disclosed is a fluorine-containing polyacrylate block copolymer binder. Also provided are a method for improving the bonding strength of a membrane electrode by bonding CCM and a supporting material by using a primer and an adhesive to form a fusion layer between a primer layer and an adhesive coating, and a membrane electrode and a preparation method therefor.

Description

Fluorine-containing binder, membrane electrode and preparation method thereof Technical field

The invention relates to a fluorine-containing binder (binder) used for a membrane electrode of a fuel cell, a membrane electrode using the binder, and a method for preparing the membrane electrode, belonging to the field of binders and membrane electrodes of fuel cells.

Background technique

Some materials have low surface energy or high crystallinity or non-polar characteristics, making it difficult to use ordinary adhesives for bonding, which affects their use, such as fluorine-containing polymer materials. The existing methods for improving the bonding performance of difficult-to-stick materials are roughly divided into two types: surface treatment of the difficult-to-stick materials and the use of new adhesives. Although the method of surface treatment of difficult-to-stick materials can improve the bonding performance of difficult-to-stick materials to a certain extent, the production process is more complicated, especially in some special industries, such as fuel cell membrane electrode manufacturing industry, material surface treatment Will increase the process and prolong the production time.

The existing methods for improving the bonding performance of difficult-to-stick materials are roughly divided into two types: surface treatment of the difficult-to-stick materials and the use of new adhesives. One of the most commonly used surface treatment methods is to coat a layer of primer on the surface of the difficult-to-stick material, and then use an adhesive to bond it after the primer is completely dried. However, this method is also very limited in improving the bonding performance of difficult-to-stick materials, especially in some special industries, such as the fuel cell membrane electrode manufacturing industry. The effect of increasing the bonding performance produced by this method does not make people satisfaction.

In the fuel cell membrane electrode manufacturing industry, adhesives are often used to bond CCM (Catalyst Coated Membrane) and a (frame-shaped) support material with a central hole together. At present, the commonly used adhesives include acrylic and epoxy Or polyolefin polymers. The CCM is composed of a catalyst layer and a film. The film is generally a perfluorosulfonic acid resin film, and the support material is generally polyethylene terephthalate (PET), polyimide (PI), and poly 1,6-naphthalene Hydrocarbon polymers such as ethylene formate (PEN), polyphenylene sulfide (PPS), polyether ketone (PEK) and polycarbonate (PC). The perfluorosulfonic acid resin membrane is a high molecular polymer with fluorine atoms in the main chain and side chains. Since the bond energy of the CF bond is as high as 485kJ·mol/L, it is the largest bond energy of all covalent bonds. Different from the zigzag-like carbon chain of the molecule on the main chain of hydrocarbon polymer, after the hydrogen atom is replaced by fluorine, the electron density of the electronegative fluorine atom is higher, and the radius of the fluorine atom is larger than that of the hydrogen atom, resulting in higher perfluorine The CCC bond angle on the molecular backbone becomes smaller, the fluorine atoms are distributed in a spiral along the carbon chain, and the sum of the van der Waals radii of the two fluorine atoms is 2.7×10 ^-10 m, which just fills the gap between the two carbon atoms, forming a The structure in which a layer of fluorine atoms wraps the internal carbon atoms. Due to the high electronegativity of fluorine atoms and low polarization rate, the surface energy of perfluoropolymer is very low, and the adhesion between perfluoropolymer and other materials is poor. Therefore, the existing adhesives used to bond the support material and the CCM cannot have a good adhesion effect on the support material and the perfluorosulfonic acid resin film, and may fall off or peel off, resulting in low efficiency in the process of membrane electrode processing. The low yield of membrane electrodes seriously affects the performance and service life of membrane electrodes. Therefore, it is necessary to develop an adhesive for bonding fluorine-containing materials.

In addition, the bonding strength between the edge of the CCM (Catalyst Coated Membrane) and the (frame-shaped) support material with a central hole needs to be further improved.

Summary of the invention

In order to overcome the shortcomings in the prior art, the purpose of the present invention is a fluorine-containing binder (binder), and also provide a membrane electrode with improved bonding strength for fuel cell membranes, and the preparation of membranes Electrode method.

According to the first embodiment of the present invention, a fluorine-containing polyacrylate block copolymer binder having the general formula (I) is provided:

The structure of the Rf group is CF ₃ (CF ₂ ) _k (CH ₂ ) _l , k is an integer from 0 to 12 (preferably 1 to 5, such as 2 to 3), and l is 0 or 1; the structure of the R group Is CH ₃ (CH ₂ ) _x , x is an integer from 0 to 12 (preferably from 1 to 5, such as 2 to 3); m and n are each an integer from 5 to 90, and m+n=30-180; preferably Yes, m and n are each an integer from 10 to 75, and m+n=50-150, more preferably m+n=70-130. More preferably, m and n are each an integer of 15-60, and more preferably an integer of 20-50. More preferably, m+n=80-110.

Preferably, m:n=0.3-3:1, preferably 0.5-2:1, more preferably 0.7-1.6:1, more preferably 0.8-1.2:1.

Generally, the number average molecular weight (Mn) of the binder is 5×10 ³ to 6×10 ⁴ , preferably 2×10 ⁴ to 5×10 ⁴ , and more preferably 3×10 ⁴ to 4.8×10 ⁴ .

According to a second embodiment of the present invention, there is provided a method for preparing the above-mentioned binder of general formula (I), the method comprising the following steps:

Dissolve CH ₂ =CH-COOCH ₂ Rf monomer in an organic solvent (for example, aromatic hydrocarbons, such as benzene or toluene) to obtain a monomer with a concentration of 20-60wt% (preferably 25-50wt%, such as 30wt% or 40wt%) The body solution is added to the polymerization reactor, the catalytic system and initiator are added, the temperature is raised (for example, to 60-100 ℃), (preferably under an inert gas such as nitrogen or argon atmosphere) to carry out the polymerization reaction; add to the polymerization reaction system CH ₂ = CH-COOR monomer, raise the temperature (for example, to 60-100°C), (preferably under an inert gas such as nitrogen or argon atmosphere), perform polymerization again; then separate and purify (for example, filter, the filtrate is the reaction mixture Use 2 to 5 times the volume of the filtrate to precipitate polymer solids from the filtrate, and the precipitated polymer solids are washed with deionized water several times), dried (for example, the obtained polymer solids are kept under vacuum at 40-60℃ ( Such as drying at 50°C for 18-30 hours) to obtain a fluorinated polyacrylate block copolymer binder of general formula (I);

The structure of the Rf group is CF ₃ (CF ₂ ) _k (CH ₂ ) _l , k is an integer from 0 to 12 (preferably 1 to 5, such as 2 to 3), and l is 0 or 1, and the structure of the R group Is CH ₃ (CH ₂ ) _x , and x is an integer of 0-12 (preferably 1-5, such as 2-3).

Preferably, the ratio of the amount (mol) of CH ₂ =CH-COOCH ₂ Rf monomer to the amount (mol) of CH ₂ =CH-COOR monomer = 5～90:5～90, more preferably 10～75 : 10 to 75, more preferably 15 to 60: 15 to 60, more preferably 20 to 50: 20 to 50, preferably 0.8 to 1.2:1.

Preferably, the above-mentioned catalytic system includes cuprous bromide and pentamethyldiethylenetriamine, and the above-mentioned initiator is ethyl 2-bromoisobutyrate.

The two monomers used in the above method are prepared by the following method: the alcohol compound RfCH ₂ -OH or R-OH is dissolved in an organic solvent to form 15-60wt% (preferably 20-50wt%, such as 30wt% Or 40wt%) concentration of alcohol solution, and then add (for example, 0.1-10wt%, based on the mass of alcohol) radical polymerization inhibitor; add triethylamine as a catalyst (used to complex the generated hydrogen chloride), the resulting The reaction system (for example, with an ice water bath) is cooled (for example, cooled to below 10°C), and the acrylic chloride monomer is added dropwise under stirring. The dropping rate should be such that the temperature of the reaction system is not higher than 50°C; after the addition is complete, stir Continue the reaction (for example 0.5-2 hours); then separate and purify to obtain a monomer with CH ₂ =CH-COOCH ₂ Rf or CH ₂ =CH-COOR, wherein the structure of the Rf group is CF ₃ (CF ₂ ) _k (CH ₂ ) _l , k is an integer from 0 to 12 (preferably 1 to 5, such as 2 to 3), l is 0 or 1, the structure of the R group is CH ₃ (CH ₂ ) _x , and x is 0 to 12 (Preferably an integer of 1 to 5, such as 2 to 3).

More specifically, a method for preparing an adhesive is provided. The method includes the following steps:

(1) Preparation of acrylate monomer: Dissolve alcohol containing RfCH ₂ group or R group (ie alcohol RfCH ₂ -OH or R-OH) in an organic solvent, and prepare an alcohol solution with a concentration of 15-60% by weight, Add a polymerization inhibitor to the alcohol-containing solution. The amount of the polymerization inhibitor is 0.1-10% by weight of the alcohol containing the RfCH2 group or the R group; then the catalyst triethylamine is added to complex the hydrogen chloride produced, with ice Cool the reaction system to below 10°C in a water bath, add acrylic chloride monomer dropwise under stirring, observe the temperature and control the dropping rate so that the temperature is not higher than 50°C; after the monomer is added dropwise, continue stirring at room temperature for 0.5-2 After hours, the reaction product was poured into 1 to 3 times the volume of deionized water and washed, and the organic layer and the water layer were separated using a separatory funnel. After washing several times, the combined organic layers were dried overnight with MgSO ₄ ; RfCH acrylate monomer containing group or R ₂ group to give after crystallization purification, the acrylate monomer containing RfCH ₂ R group or groups is placed in cold storage in the refrigerator;

(2) Synthesis of fluorine-containing block copolymer: The acrylate monomer containing RfCH ₂ group prepared in step (1) is dissolved in a solvent at a mass concentration of 20-60%, and a catalytic system and initiator are added. React at 60～100℃ under argon atmosphere for 6～24 hours; after the polymerization reaction is completed, cool to room temperature under argon atmosphere, then add R group-containing acrylate monomer, heat up to 60～100℃, React for another 6-24 hours under argon atmosphere. After the polymerization reaction is completed, filter, take the filtrate, precipitate polymer solids from the filtrate with 2 to 5 times the volume of the filtrate, and wash the precipitated polymer solids with deionized water For several times, the obtained polymer solids were dried under vacuum at 50°C for 24 hours to obtain fluorine-containing block copolymers;

The catalytic system includes cuprous bromide and pentamethyldiethylenetriamine, the initiator is ethyl 2-bromoisobutyrate, and the acrylate monomer containing RfCH ₂ group: ethyl 2-bromoisobutyrate: penta The ratio of methyldiethylenetriamine: cuprous bromide is: 40:0.8-1.2:1.6-2.4:0.8-1.2, preferably 40:1:2:1; the solvent is a non-polar aromatic hydrocarbon solvent, The solvent is subjected to water removal treatment; the molar ratio of the triethylamine to the alcohol containing the RfCH ₂ group or the R group is 1.01:1 to 1.2:1, and the acrylic chloride monomer and the RfCH ₂ group-containing alcohol The molar ratio of the alcohol of the group or the R group is 1.01:1 to 1.2:1; the molar ratio of the monomer containing the RfCH ₂ group and the R group used in the step (2) is 0.8-1.2:1, Preferably 1:1.

In the case of no primer, the above-mentioned binder can be directly used to bond membrane electrodes; or, the binder can be formulated into an adhesive mixture (ie, the first fluorine-containing adhesive described below) And the latter is directly used for bonding membrane electrodes. The adhesive mixture is prepared by mixing 65 to 95 parts by weight of the above-mentioned binder, and 1 to 5 parts by weight of an initiator (for example, an inorganic or organic peroxide initiator, such as benzoyl peroxide or two Tert-butyl), 1 to 5 parts by weight of curing agent (for example, aromatic amines, such as m-phenylenediamine or p-phenylenediamine), 3 to 25 parts by weight of toughening agent dissolved in the second organic solvent Forming.

The preparation method of the membrane electrode includes: coating a binder or an adhesive mixture on the surface of a frame-shaped support material, attaching the CCM to the frame-shaped support material, heating to 80-150°C, and curing for 5-300s.

Of course, the above-mentioned binder and primer can also be used in combination to bond the membrane electrode, as described below.

According to a third embodiment of the present invention, there is provided a method for improving the bonding strength between a frame shape support material and a catalyst-coated perfluorinated ion exchange resin membrane. The method includes the following steps:

1) Coating a primer layer on the surface to be bonded (ie, the surface or edge of the frame) of the frame-shaped support material with a central hole;

2) Before the primer layer is completely cured or when the primer layer is partially cured, the first fluorine-containing adhesive is applied on the surface of the primer layer so as to be between the primer layer and the first adhesive coating Forming a fusion layer or a transition layer or an overlapping layer (ie, an intermediate layer);

3) Stick the catalyst-coated perfluorinated ion exchange resin membrane (ie CCM) on the above-mentioned first fluorine-containing adhesive coating of the support material, so that the catalyst-coated perfluorinated ion exchange resin membrane completely covers the frame The center hole of the shaped support material;

4) Let the primer layer and the first fluorine-containing adhesive layer be completely cured (for example, by heating them to 80-150°C and holding them for 5 to 300s), so that the edges of the catalyst-coated perfluorinated ion exchange resin membrane and the frame shape The supporting materials are glued together.

Preferably, the primer includes or mainly consists of the following components: a fluoropolymer resin or a fluoro-modified polymer resin as a binder, a toughening agent (preferably a fluorine-containing rubber additive) and The first solvent.

Preferably, the first fluorine-containing adhesive is selected from fluorine-containing polyacrylate adhesives, fluorine-containing epoxy resin adhesives, fluorine-containing polyurethane adhesives, fluorine-containing silicone adhesives, and fluorine-containing silicone adhesives. One or more of polyimide adhesive and fluorine-containing polyolefin adhesive, preferably polyurethane-fluorinated epoxy acrylate adhesive or polyvinylidene fluoride adhesive; preferably, the first fluorine-containing adhesive The adhesive contains a second solvent. The first solvent and the second solvent may be the same or different.

Preferably, the primer and the first fluorine-containing adhesive are both thermosetting. The first type of fluorine-containing adhesive includes a thermal curing type in which chain extension and/or crosslinking reaction occurs under heating or a thermal curing type in which a solvent contained therein is cured by volatilization under heating. Preferably, the primer is a heat curing type in which the solvent contained therein is cured by volatilization under heating. Preferably, the first fluorine-containing adhesive is a thermal curing type in which chain extension and/or crosslinking reactions occur under heating.

According to a fourth embodiment of the present invention, there is provided a membrane electrode for a fuel cell, the membrane electrode comprising: a frame-shaped support material having a central hole, and a catalyst-coated perfluorinated ion that completely covers the central hole of the frame-shaped support material Exchange resin membrane, a sheet-like cathode gas diffusion component bonded on one surface of a catalyst-coated perfluoroion exchange resin membrane, and a sheet bonded to the other surface of a catalyst-coated perfluoroion exchange resin membrane The anode gas diffusion assembly is characterized in that between the frame-shaped support material and the catalyst-coated perfluorinated ion exchange resin membrane, there is a cured primer layer adhered to the frame-shaped support material and the perfluorinated ion exchange resin film. The cured first fluorine-containing adhesive layer on the exchange resin film, and the fusion layer or transition layer or overlapping layer (ie, the intermediate layer) formed by the mutual penetration of the primer and the first fluorine-containing adhesive between them ).

According to a fifth embodiment of the present invention, there is provided a method for preparing the above-mentioned membrane electrode, the method including the following steps:

1) Coating a primer layer on the surface to be bonded (ie, the surface or edge of the frame) of the frame-shaped support material with a central hole;

2) Before the primer layer is completely cured or when the primer layer is partially cured, the first fluorine-containing adhesive is applied on the surface of the primer layer so as to be between the primer layer and the first adhesive coating Forming a fusion layer or a transition layer or an overlapping layer (ie, an intermediate layer);

3) Stick the catalyst-coated perfluorinated ion exchange resin membrane (ie CCM) on the above-mentioned first fluorine-containing adhesive coating of the support material, so that the catalyst-coated perfluorinated ion exchange resin membrane completely covers the frame The center hole of the shaped support material;

4) Let the primer layer and the first fluorine-containing adhesive layer be completely cured (for example, by heating them to 80-150°C and holding them for 5 to 300s), so that the edges of the catalyst-coated perfluorinated ion exchange resin membrane and the frame shape The supporting materials are glued together;

5) Use the second adhesive to bond the sheet-shaped cathode gas diffusion assembly to one surface of the catalyst-coated perfluorinated ion exchange resin membrane, so that the sheet-shaped cathode gas diffusion assembly covers one surface of the CCM;

6) Use the third adhesive to bond the sheet anode gas diffusion assembly to the other surface of the catalyst-coated perfluorinated ion exchange resin membrane so that the sheet anode gas diffusion assembly covers the other surface of the CCM; and

7) Curing and forming to obtain membrane electrode;

The second adhesive and the third adhesive can be the same or different.

Preferably, the primer includes or mainly consists of the following components: a fluoropolymer resin or a fluoro-modified polymer resin as a binder, a toughening agent (preferably a fluorine-containing rubber additive) and The first solvent.

Preferably, the first fluorine-containing adhesive is selected from fluorine-containing polyacrylate adhesives, fluorine-containing epoxy resin adhesives, fluorine-containing polyurethane adhesives, fluorine-containing silicone adhesives, and fluorine-containing silicone adhesives. One or more of polyimide-based adhesives and fluorine-containing polyolefin-based adhesives are preferably polyurethane-fluorinated epoxy acrylate adhesives or polyvinylidene fluoride adhesives. Further preferably, the first fluorine-containing adhesive is a polyurethane-fluorinated epoxy acrylate adhesive or a polyvinylidene fluoride adhesive.

Preferably, the first fluorine-containing adhesive contains a second organic solvent.

Preferably, the first fluorine-containing adhesive is prepared by mixing 65 to 95 parts by weight of the above-mentioned binder and 1 to 5 parts by weight of an initiator (for example, an inorganic or organic peroxide type initiator, such as benzyl peroxide). Acyl or di-tert-butyl peroxide), 1 to 5 parts by weight of curing agent (for example, aromatic amines, such as m-phenylenediamine or p-phenylenediamine), and 3 to 25 parts by weight of toughening agent dissolved in the second Formed in a kind of organic solvent. The first solvent and the second solvent may be the same or different.

Preferably, the primer, the first fluorine-containing adhesive, the second adhesive and the third adhesive are all thermosetting.

Generally, the first fluorine-containing adhesive, the second adhesive and the third adhesive mentioned above can be the same or different.

Preferably, considering the bonding strength of each of the sheet-shaped cathode gas diffusion assembly and the sheet-shaped anode gas diffusion assembly to the CCM, the second adhesive and the third adhesive may be the same or different and independently are epoxy resin adhesives, The polyolefin-based adhesive or polyacrylate-based adhesive is more preferably an epoxy resin-based adhesive or polyacrylate-based adhesive.

Preferably, the primer includes a fluorine-modified polymer resin, a toughening agent, and an organic solvent (for example, methyl isobutyl ketone). More preferably, the fluorine-modified polymer resin is selected from vinyl fluoride-vinyl ether copolymers (for example, vinyl fluoride-perfluorovinyl perfluoro C2-C4 alkylene ether sulfonic acid copolymer), partial Difluoroethylene-vinyl ether copolymer (for example, vinylidene fluoride-perfluorovinyl perfluoro C2-C4 alkylene ether sulfonic acid copolymer), tetrafluoroethylene-vinyl perfluoroalkylene ether sulfonic acid copolymer (E.g. tetrafluoroethylene-perfluorovinyl perfluoro C2-C4 alkylene ether sulfonic acid copolymer), perfluoropropylene-vinylidene fluoride polymer, perfluoropropylene-perfluoroethylene-vinyl ether copolymer (For example, perfluoropropylene-perfluoroethylene-perfluorovinyl perfluoro C2-C4 alkylene ether sulfonic acid) one or more. The number average molecular weight Mn (GPC) of these fluoro-modified polymer resins is generally between 40,000 and 60,000, for example, about 50,000.

Preferably, the toughening agent is selected from carboxylated nitrile rubber, neoprene, chlorosulfonated polyethylene, ABS resin, or perfluoropropylene-vinylidene fluoride rubber and ethylene-vinyl acetate polymer according to 15-45: One or more of the mixture of 85-55 weight ratio. The number average molecular weight Mn (GPC) of these polymers as toughening agents is generally between 40,000 and 60,000, for example, about 50,000.

In this application, the frame-shaped support material (for example, polyester film) has a hole punched out in the center. Generally, the area of the center hole accounts for 50-96% of the area of the entire frame, preferably 70-95%, more preferably 80-92%, such as 80% or 88%. The outline of the frame of the frame-shaped supporting material may be square, rectangular or circular. The outline of the central hole can also be square, rectangular or circular.

It should be emphasized here that the various organic solvents used above can be the same or different. And it is easily selected by those skilled in the art.

The CCM (Catalyst Coated Membrane) used in this application and the (frame-shaped) support material with a central hole are all commercially available products.

In this application, generally speaking, the thickness of the primer layer is 1-10 μm, preferably 3-7 μm, more preferably 4-6 μm. The thickness of the adhesive layer used in combination with the primer layer is 2 to 50 μm, preferably 5 to 40 μm, more preferably 8 to 35 μm, more preferably 15 to 30 μm, such as 20 or 25 μm.

The thickness of the fusion layer (or transition layer or overlap layer) between the primer layer and the adhesive layer is generally 0.5 to 3 μm, 0.7 to 2 μm.

In the present application, before the primer layer is completely cured or in the case where the primer layer is partially cured, the primer layer is in a partially dried and cured state or a partially wet state. In the case that the primer layer on the frame-shaped support material is partially cured, the first fluorine-containing adhesive is dot-coated (or sprayed) on the surface of the primer layer, and the solvent contained in the adhesive (that is, the second organic solvent) ) Can swell the primer and be self-volatile, so that the first fluorine-containing adhesive can gradually penetrate into the primer layer before the solvent is completely volatilized, forming a fusion layer or overlapping layer, and after the solvent is completely volatilized, The first fluorine-containing adhesive no longer enters the primer layer.

Generally, the mass fraction of the solvent (ie, the second organic solvent) contained in the first fluorine-containing adhesive is 5-50 wt%. The boiling point of the solvent is generally 60 to 150°C, preferably 75 to 130°C, more preferably 90 to 120°C.

Preferably, the fluorine-modified polymer resin used in the primer includes one or more of a solubilizing functional group, an adhesive functional group, a crosslinking curable functional group, and a rheological promoting functional group.

Compared with the prior art, the present invention has the following beneficial technical effects:

1. The adhesive of the general formula (I) of the present invention includes a fluorine-containing block copolymer. Because the fluorine-containing block copolymer adhesive has phase separation, the fluorine-containing section will aggregate to form a fluoride-philic phase, while the hydrocarbon The part of the fluorine-containing hard-to-stick material will aggregate to form a hydrocarbon-philic phase, so that this kind of adhesive can have good adhesion to hydrocarbons and fluorine-containing hard-to-stick materials at the same time, even if no primer is used when bonding fluorine-containing hard-to-stick materials It can have better bonding performance, in which the size of the phase separation size can be adjusted according to the molecular weight of each segment of the polymer and the relative ratio of the molecular weight to achieve the best bonding effect.

2. The method of the present invention firstly performs primer treatment on the material to be bonded. Before the primer is completely cured, the first fluorine-containing adhesive is used to treat the surface of the primer so that the primer and the first fluorine-containing A fusion layer or overlapping layer between the primer and the first fluorine-containing adhesive is formed between the adhesives. After the primer and the first fluorine-containing adhesive are completely cured, the first fluorine-containing adhesive and the primer in the overlapping layer are fused with each other Cured together, there is no clear interface, so the adhesion between the first fluorine-containing adhesive and the primer is improved, and the primer and the first fluorine-containing adhesive treat the bonding material "frame-shaped support material" and The other material to be bonded (CCM) has good bonding performance, thereby improving the bonding strength between the support material and the CCM.

3. When the adhesive containing the binder of the general formula (I) is used in combination with the primer, a thicker fusion layer or overlapping layer can be obtained, and the bonding strength of the frame-shaped support material and the CCM can be further improved.

Detailed ways

The present invention further describes the technical solutions in detail through the following embodiments, but the present invention is not limited to these embodiments.

The supporting material (DuPont Teijin Films,

542, thermoplastic polyester film material), cathode gas diffusion components (SGL, Sigracet GDL 25 BC) and anode gas diffusion components (SGL, Sigracet GDL 25 BC) are commercially available products. Shui On Composites Co., Ltd. in Guangdong Province, China, Gore (GORE) and Fuel Cells ETC in the United States all sell such products. As a CCM, a perfluorinated ion exchange resin coated with platinum metal nanoparticles (such as

Resin) membrane, you can use self-made components, which are based on the "Durability and degradation analysis of hydrocarbon ionomer membrane in polymer electrolyte fuel cells accelerated stress evaluation", <Journal of Power Sources>, 2017, Issue 367, pages 63-71 ( oF: Ryo Shimizu et 2.1 part) was prepared as described. In addition, the membrane (CCM) of perfluorinated ion exchange resin (such as Nafion resin) coated with platinum metal nanoparticles can also be described in CN106848355A, CN1992400 A, CN103682386 A, CN109088073 A, CN108075158 A, CN109860630 A and CN102544558 A. The method disclosed in.

Preparation Example 1

The binder of this embodiment is applied to the fuel cell field, and the adhesive is used to bond the CCM and the supporting material in the membrane electrode of the fuel cell.

The preparation method of the binder (binder) includes the following steps:

(1) Preparation of monomer: solvent benzene undergoes water removal treatment. Dissolve CF ₃ CH ₂ OH or CH ₃ OH in benzene to prepare a benzene solution of CF ₃ CH ₂ OH or CH ₃ OH with a concentration of 20% by weight, and add to the benzene solution of CF ₃ CH ₂ OH or CH ₃ OH Radical polymerization inhibitor 2,6-di-tert-butyl-4-cresol, the amount of polymerization inhibitor is 0.2wt% of CF ₃ CH ₂ OH or CH ₃ OH; then add the catalyst triethylamine for complexation The generated hydrogen chloride, where the molar ratio of triethylamine to CF ₃ CH ₂ OH or CH ₃ OH is 1.05:1. Cool the reaction system to 6°C with an ice water bath, and add acrylic chloride monomer dropwise under stirring , The molar ratio of acryloyl chloride monomer to CF ₃ CH ₂ OH or CH ₃ OH is 1.05:1. Observe the temperature to control the dropping rate so that the temperature is not higher than 50℃; after the monomer is added, continue to stir at room temperature for 0.5 After hours, the reaction product was poured into 1.2 times volume of deionized water and washed, and the organic layer and the aqueous layer were separated using a separatory funnel. After washing 3 times, the combined organic layer was dried overnight with MgSO ₄ ; Crystallize to obtain purified monomers containing CF ₃ CH ₂ groups or CH ₃ groups, respectively, and store the monomers containing CF ₃ CH ₂ groups or CH ₃ groups in a refrigerator at low temperature;

(2) Synthesis of fluorine-containing block copolymer: The monomer containing CF ₃ CH ₂ group prepared in step (1) is dissolved in benzene to obtain a solution with a concentration of 20% by weight, and then cuprous bromide and pentamethyl are added. Diethylenetriamine and ethyl 2-bromoisobutyrate, monomers containing CF ₃ CH ₂ groups: ethyl 2-bromoisobutyrate: pentamethyldiethylenetriamine: weight of cuprous bromide The ratio is 42:1:2.1:1, and react at 60°C under argon atmosphere for 25 hours; after the polymerization reaction is completed, cool to room temperature under argon atmosphere, and then add monomers containing CH ₃ groups, containing CH ₃ The molar ratio of the monomer of the group to the monomer containing the CF ₃ CH ₂ group is 1:1, the temperature is raised to 60°C, and the reaction is continued for 25 hours under an argon atmosphere. After the polymerization reaction is completed, the mixture is filtered to obtain the filtrate Two times the volume of the filtrate was used to precipitate polymer solids from the filtrate. The precipitated polymer solids were washed with 220 mL of deionized water each time for a total of 2 washes. The resulting polymer solids were dried under vacuum at 40°C for 24 hours. The fluorine-containing block copolymer 1 was obtained.

The fluorinated block copolymer has the following structural formula:

Among them, the structure of the Rf group is CF ₃ ; the structure of the R group is CH ₃ ; m:n=1:1.

Its number average molecular weight Mn measured by GPC method was 47,300.

The method when the binder (binder) of this embodiment is used for bonding CCM and support material includes the following steps: dissolving binder, initiator, curing agent and toughening agent in a solvent, and then coating After being placed on the surface of the support material, the CCM is attached to the support material, and the temperature is raised to cure. The curing temperature of the adhesive is 80°C, and the curing time of the adhesive is 300s. Among them, the mass percentages of binder, initiator, curing agent and toughening agent are: 65% of binder, 5% of initiator, 5% of curing agent, 25% of toughening agent; initiator is peroxide Benzoyl, curing agent is m-phenylenediamine, and toughening agent is carboxyl nitrile rubber (GPC number average molecular weight Mn is 52000).

Preparation Example 2

The binder of this embodiment is applied to the fuel cell field, and the adhesive is used to bond the CCM and the supporting material in the membrane electrode of the fuel cell.

The preparation method of binder includes the following steps:

(1) Preparation of monomer: Toluene undergoes dewatering treatment, and CF ₃ (CF ₂ ) ₂ CH ₂ OH or CH ₃ (CH ₂ ) ₂ OH is dissolved in toluene to prepare 30wt% CF ₃ (CF ₂ ) ₂ (CH ₂ )OH or CH ₃ (CH ₂ ) ₂ OH in toluene solution, add free radical to the toluene solution of CF ₃ (CF ₂ ) ₂ (CH ₂ )OH or CH ₃ (CH ₂ ) ₂ OH to inhibit polymerization The quality of the polymerization inhibitor is 4.2wt% of CF ₃ (CF ₂ ) ₂ (CH ₂ )OH or CH ₃ (CH ₂ ) ₂ OH; then the catalyst triethylamine is added to complex the generated hydrogen chloride, Among them, the molar ratio of triethylamine to CF ₃ (CF ₂ ) ₂ (CH ₂ )OH or CH ₃ (CH ₂ ) ₂ OH is 1.08:1, and the reaction system is cooled to 7°C with an ice water bath, and under stirring conditions Add acryloyl chloride monomer dropwise, the molar ratio of acryloyl chloride monomer to CF ₃ (CF ₂ ) ₂ (CH ₂ )OH or CH ₃ (CH ₂ ) ₂ OH is 1.15:1. Observe the temperature to control the dropping rate to make The temperature of the reaction system is not higher than 50°C; after the monomer is added dropwise, continue to stir at room temperature for 1 hour, then pour the reaction product into 2 times volume of deionized water to wash, use a separatory funnel to separate the organic layer and the water layer, After washing 4 times, the combined organic layer was dried overnight with MgSO ₄ ; then the organic layer was recrystallized with toluene to obtain purified CF ₃ (CF ₂ ) ₂ CH ₂ group or CH ₃ (CH ₂ ) ₂ group The monomer containing CF ₃ (CF ₂ ) ₂ CH ₂ group or CH ₃ (CH ₂ ) ₂ group is stored in the refrigerator at low temperature;

(2) Synthesis of fluorinated block copolymer: the monomer containing CF ₃ (CF ₂ ) ₂ CH ₂ group prepared in step (1) is dissolved in toluene to obtain a 38wt% monomer solution, and then bromine is added Cuprous chloride, pentamethyldiethylenetriamine and ethyl 2-bromoisobutyrate, among them, monomers containing CF ₃ (CF ₂ ) ₂ CH ₂ groups: ethyl 2-bromoisobutyrate: pentamethyl The ratio of diethylenetriamine: cuprous bromide is 42:1:2.2:1, and the reaction is carried out at 80°C under argon atmosphere for 15 hours; after the polymerization reaction is completed, cool to room temperature under argon atmosphere, and then add CH ₃ (CH ₂ ) ₂ group monomer, wherein the molar ratio of the monomer containing CH ₃ (CH ₂ ) ₂ group to the monomer containing CF ₃ (CF ₂ ) ₂ CH ₂ group is 1:1 After the polymerization reaction is over, the mixture is filtered. The obtained filtrate is used to precipitate polymer solids from the filtrate with 4 times the volume of the filtrate. The precipitated polymer solids are It was washed with 200 mL of deionized water for three times, and the obtained polymer solid was dried under vacuum at 50° C. for 24 hours to obtain fluorine-containing block copolymer 2.

The fluorinated block copolymer has the following structural formula:

Wherein, the structure of the Rf group is CF ₃ (CF ₂ ) ₂ CH ₂ ; the structure of the R group is CH ₃ (CH ₂ ) ₂ ; m:n=1:1.

Its number average molecular weight Mn measured by GPC method is 48,500.

The method when the binder (binder) of this embodiment is used for bonding CCM and support material includes the following steps: dissolving binder, initiator, curing agent and toughening agent in a solvent, and then coating After the surface of the support material, the CCM is attached to the support material, and the temperature is raised to cure. The curing temperature of the adhesive is 110°C, and the curing time of the adhesive is 120s. Among them, the mass percentages of binder, initiator, curing agent and toughening agent are: 70% of the binder, 5% of the initiator, 5% of the curing agent, and 20% of the toughening agent; the initiator is peroxide Benzoyl, curing agent is m-phenylenediamine, and toughening agent is carboxyl nitrile rubber (GPC number average molecular weight Mn is 52000).

Preparation Example A

Preparation of polyurethane-fluorinated epoxy acrylate adhesive

In accordance with the "polyurethane - a synthetic single-component epoxy adhesive fluorinated acrylate", "Polymer Science and Engineering", 2013, 03 (Author: Lui Hung incense, Hefei University of Polymer Science and Engineering) of 1.2 The preparation method described in section .2, firstly, react with isophorone diisocyanate, hydroxyethyl acrylate and methyl ethyl ketoxime as raw materials to obtain a blocked isocyanate-acrylate monomer, and then use this monomer to shrink with methacrylic acid Glycerol ester and hexafluorobutyl acrylate are copolymerized to obtain polyurethane-fluorinated epoxy acrylate adhesive, referred to as "adhesive A".

Example 1

In this embodiment, the CCM is a self-made component, which is based on "Durability and degradation analysis of hydrocarbon ionomer membrane in polymer electrolyte fuel cells accelerated stress evaluation", <Journal of Power Sources>, 2017 Issue 367, pages 63-71 ( oF: Ryo Shimizu et 2.1 part) was prepared as described.

The membrane electrode preparation method includes the following steps:

(1) Cutting the PET support material (DuPont Teijin Films, Melinex 542), CCM film, cathode gas diffusion component (SGL, Sigracet GDL 25 BC) and anode gas diffusion component (SGL, Sigracet GDL 25 BC), where the size of the CCM film It is: length×width=14.6×9.6cm, others are: length×width=15×10cm; and punch out the center hole on the rectangular support material, the center hole is rectangular, the size of the center hole is: length×width =14×9cm, a frame-shaped support material is obtained.

(2) Dot apply primer on the frame-shaped support material. The wet primer layer has a thickness of 5μm and a width of 10mm; the primer is composed of the following mass percentage of raw materials: tetrafluoroethylene and CF ₂ =CF-O-CF ₂ Random copolymer of CF ₂ -SO ₃ H (ie, fluorine-modified polymer resin "tetrafluoroethylene-vinyl perfluoroalkylene ether sulfonic acid copolymer", Mn=51400, molar ratio of the two monomers It is 1:1) 42wt%, auxiliary agent 8wt%, solvent methyl isobutyl ketone 50wt%; wherein the auxiliary agent is a mixture of perfluoropropylene-vinylidene fluoride rubber and ethylene-vinyl acetate polymer, perfluoropropylene -The mass percentage of vinylidene fluoride rubber in the additives is 40wt%;

(3) After the primer is applied, after the solvent in the primer evaporates at room temperature, immediately apply an adhesive on the surface of the primer that has not been completely dried and cured. The thickness of the wet coating of the adhesive is 18μm; the adhesive is It is formed by mixing 78wt% of the adhesive A synthesized in the above preparation example A and 22wt% of methyl isobutyl ketone solvent. After the adhesive is applied, the CCM is attached to the frame-shaped support material. Before the solvent in the adhesive is completely volatilized, the solvent in the adhesive will swell the primer, and the adhesive will gradually penetrate into the primer layer to form an overlap with a thickness of 0.8μm Layer, heat up to 80℃, keep for 120s, so that the primer and adhesive layer are completely cured;

At the same time, an unpunched rectangular (15×10 cm) support material is also used to repeat the operations of steps (2) and (3) to obtain samples for testing. Samples were taken from multiple batches of products, and the samples were measured according to the Chinese standard GB/T 2792-2014 "Test Method for Peeling Strength of Adhesive Tapes" to measure the bonding strength between the support material and CCM (refer to Adhesive Tapes and Anti-sticking Material method), and the test results are shown in Table 1 as the arithmetic average of the peel strength (N/cm).

(4) Dot apply the second adhesive on the sheet-shaped cathode gas diffusion assembly. The second adhesive is bisphenol A epoxy resin (E-51). The wet coating thickness of the second adhesive is 3.5um. , The width is 10mm; after the application is finished, cover the sheet-shaped cathode gas diffusion assembly to the CCM, attach the two, and then turn over, and then attach the sheet-shaped anode gas diffusion assembly on the back side;

(5) Dot apply a third adhesive on the sheet anode gas diffusion layer. The third adhesive is the same as the second adhesive. The wet coating of the adhesive has a thickness of 3.5um and a width of 10mm; after the application is completed, The sheet anode gas diffusion assembly covers the CCM;

(6) The membrane electrode is fabricated by heating and curing, the heating temperature is 150°C, and the heating time is 120s.

Example 2 (preferred in the present invention)

Example 1 was repeated, except that in step (3), the fluorinated block copolymer 1 of Preparation Example 1 was used instead of adhesive A and perfluoropropylene-vinylidene fluoride polymer was used as the fluorine-modified polymer resin instead of tetrafluoroethylene. A random copolymer of ethylene and CF ₂ =CF-O-CF ₂ CF ₂ -SO ₃ H. An overlapped layer with a thickness of 2.1 μm was formed.

Example 3 (preferred by the present invention)

Example 1 was repeated, except that the polyphenylene sulfide support material was used instead of the PET support material and the fluorinated block copolymer 2 of Preparation Example 2 was used instead of the adhesive A in step (3). An overlapping layer with a thickness of 2.8 μm is formed.

Example 4

It is basically the same as in Example 1, except that the combination of primer and adhesive is not used, but the fluorinated block copolymer 1 of Preparation Example 1 is directly used to bond the support material and the CCM.

The membrane electrode preparation method includes the following steps:

(1) Cutting the PET support material (DuPont Teijin Films, Melinex 542), CCM film, cathode gas diffusion component (SGL, Sigracet GDL 25 BC) and anode gas diffusion component (SGL, Sigracet GDL 25 BC), where the size of the CCM film It is: length×width=14.6×9.6cm, the others are: length×width=15×10cm; and punch out the center hole on the rectangular support material, the center hole is rectangular, and the size of the center hole is: length×width =14×9cm, a frame-shaped support material is obtained.

(2) Dotting an adhesive on the frame-shaped support material, the adhesive is formed by mixing 70% by weight of the fluorinated block copolymer 1 synthesized in the above preparation example 1 and 30% by weight of methyl isobutyl ketone solvent. The thickness of the wet coating of the adhesive is 20 μm. After the adhesive is applied, the CCM is attached to the frame-shaped support material, the temperature is raised to 80°C, and the temperature is kept for 120s to fully cure the adhesive layer;

(3) Dot apply the second adhesive on the sheet-shaped cathode gas diffusion assembly. The second adhesive is bisphenol A epoxy resin (E-51). The wet coating thickness of the second adhesive is 3.5um. , The width is 10mm; after the application is completed, cover the sheet-shaped cathode gas diffusion assembly to the CCM, attach the two, and then turn over, and then attach the sheet-shaped anode gas diffusion assembly on the back side;

(4) Dot apply a third adhesive on the sheet anode gas diffusion layer. The third adhesive is the same as the second adhesive. The wet coating of the adhesive has a thickness of 3.5um and a width of 10mm; after the application is completed, The sheet anode gas diffusion assembly covers the CCM;

(5) The membrane electrode is fabricated by heating and curing, the heating temperature is 150°C, and the heating time is 120s.

Example 5

Example 4 was repeated, except that the fluorinated block copolymer 2 of Preparation Example 2 was directly used to bond the support material and the CCM.

Comparative example 1

Repeat Example 4, but directly use bisphenol A epoxy resin (E-51) to bond the support material and CCM.

Experimental results

Table 1 Bonding strength between support material and CCM

It can be seen from the bonding performance comparison table that when the perfluorosulfonic acid film CCM and the supporting material are bonded by the method of improving the bonding performance of the present invention, the peeling force between the two materials is much greater than that produced by using traditional adhesives. The peeling force, and the peeling force of the product of the present invention is far greater than the requirements of the membrane electrode field for the peeling force of CCM and support material. The bonding performance between CCM and the support material is high, without air leakage, and a toughening agent is used in the primer, which improves the toughness of the bonding structure and avoids the brittleness of the bonding structure caused by a wide range of temperature changes during use Cracking, piercing the membrane material, resulting in air leakage, further reducing the possibility of air leakage, improving the performance and life of the membrane electrode; on the other hand, after the CCM is bonded to the support material, continue to bond the cathode gas diffusion layer Later, when bonding the anode gas diffusion layer, there is still a reversal process. During this process, if the bonding between the CCM and the support material is not good, it may fall off and need to be re-bonded, which will greatly affect the entire production process. Therefore, the method for preparing membrane electrodes of the present invention is suitable for large-scale industrialization of membrane electrodes.

Claims (10)

1. Fluorine-containing polyacrylate block copolymer binder with general formula (I),

   

   The structure of the Rf group is CF ₃ (CF ₂ ) _k (CH ₂ ) _l , k is an integer from 0 to 12, and l is 0 or 1; the structure of the R group is CH ₃ (CH ₂ ) _x , x is An integer of 0-12; m and n are an integer of 5 to 90, and m+n=30-180; preferably, m and n are an integer of 10 to 75, and m+n=50-150, More preferably m+n=70-130;

   Preferably, m:n=0.8-1.2:1.
2. The binder according to claim 1, wherein the number average molecular weight (Mn) of the binder is 5×10 ³ to 6×10 ⁴ , preferably 2×10 ⁴ to 5×10 ⁴ , more preferably 3× 10 ⁴ to 4.8×10 ⁴ .
3. A method for preparing the adhesive according to claim 1 or 2, the method comprising the following steps:

   Add CH ₂ =CH-COOCH ₂ Rf monomer dissolved in organic solvent to 20-60wt% of the monomer solution into the polymerization reactor, add the catalytic system and initiator, increase the temperature, and carry out the polymerization reaction; Add CH ₂ =CH-COOR monomer to the system, raise the temperature, and perform polymerization again; then separate, purify, and dry to obtain a fluorinated polyacrylate block copolymer binder of general formula (I);

   The structure of the Rf group is CF ₃ (CF ₂ ) _k (CH ₂ ) _l , k is an integer from 0 to 12, l is 0 or 1, and the structure of the R group is CH ₃ (CH ₂ ) _x , x is An integer from 0 to 12; preferably, the ratio of the amount (mol) of CH ₂ =CH-COOCH ₂ Rf monomer to the amount (mol) of CH ₂ =CH-COOR monomer = 5 to 90:5 to 90, More preferably, it is 10-75:10-75, preferably 0.8-1.2:1;

   Preferably, the above-mentioned catalytic system includes cuprous bromide and pentamethyldiethylenetriamine, and the above-mentioned initiator is ethyl 2-bromoisobutyrate.
4. A method for improving the bonding strength between a support material and a perfluorinated ion exchange resin membrane coated with a catalyst. The method includes the following steps:

   1) Coating a primer layer on the surface to be bonded of the frame-shaped support material with a central hole;

   2) Before the primer layer is completely cured or when the primer layer is partially cured, the first fluorine-containing adhesive is applied on the surface of the primer layer so as to be between the primer layer and the first adhesive coating Form a fusion layer or transition layer;

   3) Attach the catalyst-coated perfluoroion exchange resin membrane to the coating of the above-mentioned first fluorine-containing adhesive of the support material so that the catalyst-coated perfluoroion exchange resin membrane completely covers the frame-shaped support material Center hole;

   4) Let the primer layer and the first fluorine-containing adhesive layer be completely cured, and allow the edges of the catalyst-coated perfluorinated ion exchange resin membrane to be bonded to the frame-shaped support material.
5. The method of claim 4, wherein:

   The primer includes or mainly consists of the following components: a fluoropolymer resin or a fluoro-modified polymer resin as a binder, a toughening agent (preferably a fluorine-containing rubber additive) and a first solvent; and/or

   The first fluorine-containing adhesive is selected from fluorine-containing polyacrylate adhesives, fluorine-containing epoxy resin adhesives, fluorine-containing polyurethane adhesives, fluorine-containing silicone adhesives, and fluorine-containing polyimides One or more of fluorine-containing polyolefin adhesives, polyurethane-fluorinated epoxy acrylate adhesives or polyvinylidene fluoride adhesives; preferably, the first fluorine-containing adhesive contains the second Kind of solvent.
6. The method according to claim 4 or 5, wherein the primer and the first fluorine-containing adhesive are both heat curing type.
7. Membrane electrode, which includes: a frame-shaped support material with a central hole, a catalyst-coated perfluorinated ion exchange resin membrane that completely covers the central hole of the frame-shaped support material, and a perfluorinated ion exchange resin membrane coated with a catalyst. A sheet-like cathode gas diffusion assembly on one surface, and a sheet-like anode gas diffusion assembly adhered to the other surface of the catalyst-coated perfluorinated ion exchange resin membrane, characterized in that the frame-shaped support material and the catalyst coated The perfluorinated ion exchange resin film has: a cured primer layer bonded to the frame-shaped support material and a cured first fluorine-containing adhesive layer bonded to the perfluorinated ion exchange resin film, and between them The fusion layer or transition layer formed by the mutual penetration of the primer and the first fluorine-containing adhesive between the two.
8. The method of preparing a membrane electrode or the method of preparing a membrane electrode of claim 7, the method comprising the following steps:

   1) Coating a primer layer on the surface to be bonded of the frame-shaped support material with a central hole;

   2) Before the primer layer is completely cured or when the primer layer is partially cured, the first fluorine-containing adhesive is applied on the surface of the primer layer so as to be between the primer layer and the first adhesive coating Form a fusion layer or transition layer;

   3) Attach the catalyst-coated perfluoroion exchange resin membrane to the coating of the above-mentioned first fluorine-containing adhesive of the support material so that the catalyst-coated perfluoroion exchange resin membrane completely covers the frame-shaped support material Center hole;

   4) Let the primer layer and the first fluorine-containing adhesive layer be completely cured, so that the edge of the catalyst-coated perfluorinated ion exchange resin membrane and the frame-shaped support material are bonded together;

   5) Use the second adhesive to bond the sheet-shaped cathode gas diffusion assembly on one surface of the catalyst-coated perfluorinated ion exchange resin membrane, so that the sheet-shaped cathode gas diffusion assembly covers the catalyst-coated perfluorinated ion exchange One surface of the resin film;

   6) Use the third adhesive to bond the sheet-shaped anode gas diffusion assembly to the other surface of the catalyst-coated perfluorinated ion exchange resin membrane, so that the sheet-shaped anode gas diffusion assembly covers the catalyst-coated perfluorinated ion The other surface of the exchange resin membrane; and

   7) Curing and forming to obtain membrane electrode;

   The second adhesive and the third adhesive can be the same or different.
9. The method according to claim 8, wherein:

   The primer includes or mainly consists of the following components: a fluoropolymer resin or a fluoro-modified polymer resin as a binder, a toughening agent (preferably a fluorine-containing rubber additive) and a first solvent; and/or

   The first fluorine-containing adhesive is selected from fluorine-containing polyacrylate adhesives, fluorine-containing epoxy resin adhesives, fluorine-containing polyurethane adhesives, fluorine-containing silicone adhesives, and fluorine-containing polyimides One or more of fluorine-containing polyolefin adhesives, polyurethane-fluorinated epoxy acrylate adhesives or polyvinylidene fluoride adhesives; preferably, the first fluorine-containing adhesive contains the second Kind of organic solvent.

   Preferably, the first fluorine-containing adhesive is prepared by mixing 65 to 95 parts by weight of the adhesive of claim 1 or 2 and 1 to 5 parts by weight of an initiator (such as benzoyl peroxide or di-tert-butyl peroxide). Base), 1 to 5 parts by weight of curing agent (such as aromatic amines), 3 to 25 parts by weight of toughening agent dissolved in the second organic solvent; generally, the first solvent and the second The solvents can be the same or different.
10. The method according to claim 8 or 9, wherein the primer, the first fluorine-containing adhesive, the second adhesive and the third adhesive are all heat-curing; preferably, the primer includes a fluorine-modified polymer Resins, toughening agents and organic solvents (such as methyl isobutyl ketone); more preferably, the fluorine-modified polymer resin is selected from vinyl fluoride-vinyl ether copolymers, vinylidene fluoride-ethylene One of base ether copolymer, tetrafluoroethylene-vinyl perfluoroalkylene ether sulfonic acid copolymer, perfluoropropylene-vinylidene fluoride polymer or perfluoropropylene-perfluoroethylene-vinyl ether copolymer Or multiple.

    Preferably, the toughening agent is selected from carboxylated nitrile rubber, neoprene, chlorosulfonated polyethylene, ABS resin, or perfluoropropylene-vinylidene fluoride rubber and ethylene-vinyl acetate polymer according to 15-45: One or more of the mixture of 85-55 weight ratio.

    Preferably, the second adhesive and the third adhesive may be the same or different and are each independently an epoxy resin adhesive, a polyolefin adhesive or a polyacrylate adhesive.