Post-curing acid and alkali resistant sealing frame and preparation method thereof

Abstract

The invention discloses a post-curing acid and alkali resistant sealing frame and a preparation method thereof, and relates to the technical field of fuel cell sealing frames, the post-curing acid and alkali resistant sealing frame comprises a release layer, a post-curing hot melt adhesive layer and a base material layer which are arranged in sequence; the post-curing hot melt adhesive layer is composed of acid modified polyolefin resin, sulfur-containing epoxy resin, polyester resin, silane modified polyolefin resin, a curing agent and an organic solvent according to the weight ratio of 100: (1-5): (5-10): (10-20): (0.5-5): (40-200). The temperature resistance and hydrolysis resistance of the post-curing acid and alkali resistant sealing frame are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of proton exchange membrane electrolyzer sealing frames, and specifically relates to a post-cured acid and alkali resistant sealing frame and a preparation method thereof. Background Art

[0002] A proton exchange membrane electrolyzer (PEMEC) mainly consists of a membrane electrode, a gas diffusion layer, and a bipolar plate. The membrane electrode, as the core component of the PEMEC, mainly consists of an anode catalyst layer, a proton exchange membrane, and a cathode catalyst layer. The anode catalyst mainly decomposes water into oxygen, electrons, and protons; the proton exchange membrane, as a solid electrolyte, can effectively isolate the gases generated at the anode and cathode, but protons can pass through in the form of hydrated hydrogen ions; the cathode catalyst promotes the reaction of hydrogen ions to generate hydrogen. PEM hydrogen production has a very high requirement for the gas pressure of the water electrolyzer (>2MPa), and the existing PEM water electrolyzers usually use polytetrafluoroethylene or ethylene propylene diene monomer rubber to make flat gaskets, and the structure is pressed through the bolt pre-tightening force to achieve sealing. This sealing method is difficult to position during the assembly of the electrolyzer, with complex operation and high cost. In addition, its acid and alkali resistance is poor, resulting in low encapsulation effect and service life of the membrane electrode, which limits the industrial promotion in this field. Summary of the Invention

[0003] The first technical problem to be solved by the present invention is: aiming at the deficiencies existing in the prior art, to provide a post-cured acid and alkali resistant sealing frame with good acid and alkali resistance, low cost, good encapsulation effect and service life for the membrane electrode.

[0004] To solve the above first technical problem, the technical solution of the present invention is: A post-cured acid and alkali resistant sealing frame, comprising a release layer, a post-cured hot melt adhesive layer, and a substrate layer arranged in sequence; The post-cured hot melt adhesive layer is composed of an acid-modified polyolefin resin, a sulfur-containing epoxy resin, a polyester resin, a silane-modified polyolefin resin, a curing agent, and an organic solvent with a weight ratio of 100:(1 - 5):(5 - 10):(10 - 20):(0.5 - 5):(40 - 200).

[0005] Preferably, the acid-modified polyolefin resin is modified by one of maleic anhydride or acrylic acid; The acid-modified polyolefin resin is a non-chlorinated acid-modified polyolefin resin, with a weight average molecular weight of 500,000 - 1,000,000 and an acid value of 2 - 50mgKOH / g.

[0006] Preferably, the sulfur-containing epoxy resin is an epoxy resin modified by polysulfide with a polysulfide skeleton as the main chain.

[0007] Preferably, the polyester resin is a carboxyl-terminated hyperbranched polyester resin with a molecular weight of 1000 - 15000 g / mol and a degree of branching of 50 - 80%.

[0008] Preferably, the silane-modified polyolefin resin is an amorphous-a-polyolefin containing siloxane.

[0009] Preferably, the curing agent is one of an isocyanate curing agent or a carbodiimide curing agent, and the mass ratio of carbodiimide to epoxy silane coupling agent in the carbodiimide curing agent is 1:0.5 - 0.7.

[0010] Preferably, the organic solvent is any one of ethyl acetate, acetone, butanone, cyclohexanone, methyl isobutyl ketone, toluene, xylene, cyclohexane or a mixed solution thereof.

[0011] Preferably, the release layer is a grid release film or a matte release film with a grid shape, and the thickness of the release layer is 25 - 100 μm.

[0012] Preferably, the substrate layer is one of PPS material or PPSU material, the thickness of the substrate layer is 25 - 250 μm, and the surface of the substrate layer is subjected to corona treatment before use to make the dyne value ≥ 40; The thickness of the post-curing hot melt adhesive layer is 10 - 40 μm.

[0013] The second technical problem to be solved by the present invention is: aiming at the deficiencies existing in the prior art, to provide a preparation method of a post-curing acid-alkali resistant sealing frame, the obtained sealing frame has good acid-alkali resistance, low cost, good encapsulation effect and service life for the membrane electrode.

[0014] To solve the above second technical problem, the technical solution of the present invention is: A preparation method of a post-curing acid-alkali resistant sealing frame, comprising the following steps: S1. Preparation of the post-curing hot melt adhesive Add an acid-modified polyolefin resin and an organic solvent into an autoclave, dissolve at 60 °C, then raise the temperature to 70 °C, add a sulfur-containing epoxy resin, a polyester resin and a silane-modified polyolefin resin, continue to stir and dissolve at 70 - 80 °C, and perform ultrasonic-assisted dispersion at 20 - 40 kHz to eliminate bubbles. After complete dissolution, cool to room temperature, filter and pour out to obtain the post-curing hot melt adhesive; S2. Preparation of the post-curing hot melt adhesive layer The post-curing hot-melt adhesive prepared in step S1 is added with a curing agent and stirred evenly, filtered through a 200-800 mesh sieve or a 1-20 μm filter element, and then coated on the substrate layer by a doctor blade coater or a CED coater, dried at 80-150 °C for 3-10 min, and then an isolation layer is attached to prepare a post-curing acid and alkali resistant sealing frame.

[0015] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: 1. The present invention uses an acid-modified polyolefin resin with a hot-melt bonding effect, combined with a polyepoxide resin modified with a polysulfide skeleton as the main chain, and a carboxyl-terminated hyperbranched polyester resin to react with a curing agent to form a highly crosslinked interpenetrating network structure, ensuring high bonding strength during the initial hot pressing of the product. Moreover, the polysulfide skeleton structure can also ensure the flexibility and impact resistance of the adhesive layer after curing. At the same time, the silane-modified polyolefin resin can further react and crosslink with moisture to achieve post-stage reaction curing, improving the temperature resistance and hydrolysis resistance of the post-curing acid and alkali resistant sealing frame.

[0016] 2. The present invention uses a coating method to prepare a post-curing acid and alkali resistant sealing frame, which not only has a simple production process but also the prepared post-curing acid and alkali resistant sealing frame products have high consistency and high quality.

[0017] 3. The acid-modified polyolefin resin, sulfur-containing epoxy resin, carboxyl-terminated hyperbranched resin, and silane-modified resin materials used in the post-curing hot-melt adhesive layer of the present invention have excellent acid and alkali resistance, hydrolysis resistance, and low gas permeability. Through the action of the curing agent for further reaction crosslinking, the temperature resistance, hydrolysis resistance, low compression deformation, low gas permeability and other properties of the sealing frame products can be greatly improved.

[0018] 4. The present invention uses PPS materials, PPSU materials, etc. with excellent physical and mechanical properties, gas barrier properties, chemical stability, heat resistance, ultraviolet resistance, radiation resistance and other properties as the substrate to ensure that the sealing frame products have excellent aging resistance. Specific embodiments

[0019] The following further elaborates the present invention in conjunction with embodiments. Embodiment 1

[0020] A preparation method of a post-curing acid and alkali resistant sealing frame includes the following steps: S1. Preparation of the post-curing hot-melt adhesive Add the acid-modified polyolefin resin and organic solvent into an autoclave, dissolve at 60 °C, then raise the temperature to 70 °C, add sulfur-containing epoxy resin, polyester resin and silane-modified polyolefin resin, continue stirring and dissolving at 70 °C, and perform ultrasonic-assisted dispersion at 20 kHz to eliminate bubbles. After complete dissolution, cool to room temperature, filter and pour out to obtain a post-cured hot melt adhesive. The weight ratio of the acid-modified polyolefin resin, sulfur-containing epoxy resin, polyester resin, silane-modified polyolefin resin, curing agent and organic solvent is 100:1:5:10-20:0.5:40; Among them, the acid-modified polyolefin resin is selected as Zhengzhou Zhuoer Tai acid-modified polyolefin resin ZAR1910 (maleic anhydride grafted), and the weight-average molecular weight of the acid-modified polyolefin resin is 900,000.

[0021] The sulfur-containing epoxy resin is an epoxy resin modified with polysulfide with a polysulfide skeleton as the main chain, and specifically selected as Toray FLEP-60 from Japan.

[0022] The polyester resin is a carboxyl-terminated hyperbranched polyester resin, specifically selected as hyperbranched polyester resin HyPer C104, and its molecular weight is 12,000 g / mol.

[0023] The silane-modified polyolefin resin is an amorphous-a-polyolefin containing siloxane, specifically selected as Evonik silane-modified polyolefin resin Vestoplast 206.

[0024] The curing agent is an isocyanate curing agent, specifically selected as Japanese polyurethane isocyanate curing agent L75.

[0025] The organic solvent is a mixed solvent of xylene and toluene, and the mass ratio is 1:1.

[0026] The release layer is a grid release film with a grid shape, and the thickness of the release layer is 25 μm.

[0027] The substrate layer is made of PPS material, the thickness of the substrate layer is 25 μm, and the surface of the substrate layer is subjected to corona treatment before use to make the dyne value ≥ 40; The thickness of the hot melt adhesive layer is 10 μm.

[0028] S2. Preparation of the post-cured hot melt adhesive layer Add the curing agent to the post-cured hot melt adhesive prepared in step S1 and stir evenly, filter through a 200-mesh filter screen, then coat it on the substrate layer with a doctor blade coater, dry at 80 °C for 10 min, and then attach the release layer to prepare a post-cured acid- and alkali-resistant sealing frame. Example 2

[0029] A preparation method of a post-cured acid- and alkali-resistant sealing frame includes the following steps: S1. Preparation of Post-Curing Hot-Melt Adhesive Add acid-modified polyolefin resin and organic solvent into an autoclave, dissolve at 60 °C, then raise the temperature to 70 °C, add sulfur-containing epoxy resin, polyester resin and silane-modified polyolefin resin, continue to stir and dissolve at 70 - 80 °C, and perform ultrasonic-assisted dispersion at 20 - 40 kHz to eliminate bubbles. After complete dissolution, cool to room temperature and then filter and pour out to obtain the post-curing hot-melt adhesive. The weight ratio of acid-modified polyolefin resin, sulfur-containing epoxy resin, polyester resin, silane-modified polyolefin resin, curing agent and organic solvent is 100:2:7:12:1:70; Among them, the acid-modified polyolefin resin is Mitsui acid-modified polyolefin resin A-300PM (acrylic graft) from Japan, and the weight-average molecular weight of the acid-modified polyolefin resin is 600,000.

[0030] The sulfur-containing epoxy resin is an epoxy resin modified with polysulfide with a polysulfide backbone, specifically selected as Toray FLEP-60 from Japan.

[0031] The polyester resin is a carboxyl-terminated hyperbranched polyester resin, specifically selected as hyperbranched polyester resin HyPer C104 with a molecular weight of 12,000 g / mol.

[0032] The silane-modified polyolefin resin is an amorphous -a- polyolefin containing siloxane, specifically selected as Evonik silane-modified polyolefin resin Vestoplast 206.

[0033] The curing agent is an isocyanate curing agent, specifically selected as isocyanate curing agent HT-10 from Wanhua.

[0034] The organic solvent is ethyl acetate.

[0035] The release layer is a matte release film with a grid shape, and the thickness of the release layer is 50 μm.

[0036] The substrate layer is made of PPSU material, the thickness of the substrate layer is 100 μm, and the surface of the substrate layer is subjected to corona treatment before use to make the dyne value ≥ 40; The thickness of the hot-melt adhesive layer is 20 μm.

[0037] S2. Preparation of Post-Curing Hot-Melt Adhesive Layer Add the curing agent to the post-curing hot-melt adhesive prepared in step S1 and stir evenly, filter through a 400-mesh sieve, and then coat it on the substrate layer with a CED coater, dry at 100 °C for 8 min, and then attach the release layer to prepare a post-curing acid- and alkali-resistant sealing frame. Example 3

[0038] A preparation method of a post-cured acid and alkali resistant sealing frame, comprising the following steps: S1. Preparation of post-cured hot melt adhesive Add acid-modified polyolefin resin and organic solvent into an autoclave, dissolve at 60 °C, then raise the temperature to 70 °C, add sulfur-containing epoxy resin, polyester resin and silane-modified polyolefin resin, continue to stir and dissolve at 70 - 80 °C, and perform ultrasonic-assisted dispersion at 20 - 40 kHz to eliminate bubbles. After complete dissolution, cool to room temperature and then filter and pour out to obtain the post-cured hot melt adhesive, where the weight ratio of acid-modified polyolefin resin, sulfur-containing epoxy resin, polyester resin, silane-modified polyolefin resin, curing agent and organic solvent is 100:3:8:15:3:150; Among them, the acid-modified polyolefin resin is Zhengzhou Zhuoerte acid-modified polyolefin resin ZAR1910 (maleic anhydride grafted), and the weight average molecular weight of the acid-modified polyolefin resin is 900,000.

[0039] The sulfur-containing epoxy resin is an epoxy resin modified with polysulfide with a polysulfide skeleton as the main chain, specifically selected as Toray FLEP-50 from Japan.

[0040] The polyester resin is a terminal carboxyl hyperbranched polyester resin, specifically selected as hyperbranched polyester resin HyPer C102, and its molecular weight is 2600 g / mol.

[0041] The silane-modified polyolefin resin is an amorphous-a-polyolefin containing siloxane, specifically selected as Clariant silane-modified polyolefin resin Licocene® PE SI 3361 TP.

[0042] The curing agent is a carbodiimide curing agent, and the mass ratio of carbodiimide to epoxy silane coupling agent (KH-560) in the carbodiimide curing agent is 1:0.5.

[0043] The organic solvent is a mixed solvent of acetone, methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone, and its mass ratio is 1:1:5:1:2.

[0044] The release layer is a grid release film with a grid shape, and the thickness of the release layer is 75 μm.

[0045] The substrate layer is made of PPS material, the thickness of the substrate layer is 115 μm, and the surface of the substrate layer is subjected to corona treatment before use to make the dyne value ≥ 40; The thickness of the hot melt adhesive layer is 30 μm.

[0046] S2. Preparation of post-cured hot melt adhesive layer The post-cured hot-melt adhesive prepared in step S1 is added with a curing agent and stirred evenly, filtered through a 1μm filter element, and then coated on the substrate layer by a knife coater, dried at 120°C for 5 minutes, and then a release layer is attached to prepare a post-cured acid and alkali resistant sealing frame. Example 4

[0047] A preparation method of a post-cured acid and alkali resistant sealing frame includes the following steps: S1. Preparation of post-cured hot-melt adhesive An acid-modified polyolefin resin and an organic solvent are added to an autoclave, dissolved at 60°C, then heated to 70°C, a sulfur-containing epoxy resin, a polyester resin, and a silane-modified polyolefin resin are added, and stirring and dissolution are continued at 70-80°C. Ultrasonic-assisted dispersion is carried out at 20-40 kHz to eliminate bubbles. After complete dissolution, it is cooled to room temperature and then filtered and poured out to obtain a post-cured hot-melt adhesive, where the weight ratio of the acid-modified polyolefin resin, the sulfur-containing epoxy resin, the polyester resin, the silane-modified polyolefin resin, the curing agent, and the organic solvent is 100:5:10:20:5:200; Among them, the acid-modified polyolefin resin is selected as the acid-modified polyolefin resin ADI-1031 (maleic anhydride) of Shenyang Sinochem, the weight average molecular weight of the acid-modified polyolefin resin is 700000, and the grafting rate is 2.5%.

[0048] The sulfur-containing epoxy resin is an epoxy resin modified with polysulfide with a polysulfide skeleton, and is specifically selected as Toray FLEP-50 of Japan.

[0049] The polyester resin is a carboxyl-terminated hyperbranched polyester resin, and is specifically selected as the hyperbranched polyester resin HyPer C103 with a molecular weight of 6400 g / mol.

[0050] The silane-modified polyolefin resin is an amorphous-a-polyolefin containing siloxane, and is specifically selected as the silane-modified polyolefin resin Vestoplast 206 of Evonik.

[0051] The curing agent is a carbodiimide curing agent, and the mass ratio of carbodiimide to epoxy silane coupling agent (KH-560) in the carbodiimide curing agent is 1:0.7.

[0052] The organic solvent is cyclohexane.

[0053] The release layer is a matte release film with a grid shape, and the thickness of the release layer is 100μm.

[0054] The substrate layer is made of PPSU material, the thickness of the substrate layer is 250μm, and the surface of the substrate layer is subjected to corona treatment before use to make the dyne value ≥40; The thickness of the hot-melt adhesive layer is 40μm.

[0055] S2. Preparation of Post-Curing Hot Melt Adhesive Layer Add a curing agent to the post-curing hot melt adhesive prepared in step S1, stir evenly, filter through a 20μm filter element, then coat it on the substrate layer using a CED coater, dry at 150°C for 3 minutes, and then attach a release layer to prepare a post-curing acid- and alkali-resistant sealing frame. Comparative Example 1

[0056] Do not add sulfur-containing epoxy resin, and the rest is exactly the same as in Example 2. Comparative Example 2

[0057] Do not add silane-modified polyolefin resin, and the rest is exactly the same as in Example 2. Comparative Example 3

[0058] Do not add polyester resin, and the rest is exactly the same as in Example 2.

[0059] Test the performance of the sealing frame products in the above Examples 1-4 and Comparative Examples 1-3 respectively. The specific test items and test methods are shown in Table 1 below, and the test results are shown in Table 2.

[0060] Table 1

[0061] Table 2

[0062] Among them: 1. During the peel strength test, hot pressing is carried out at 140°C * 60s * 0.6 Mpa; 2. sf indicates that material breakage occurs during the peel strength test; 3. cf indicates that delamination occurs in the proton membrane during the peel strength test.

[0063] From the experimental data in the above table, it can be seen that by adding different ratios, a sealing frame product with excellent bonding strength and a low decrease in bonding strength after high-temperature acid boiling or alkali solution immersion can be prepared; in the present invention, an acid-modified polyolefin resin is combined with a sulfur-containing epoxy resin and a carboxyl-terminated hyperbranched polyester resin to react with a curing agent to form a highly crosslinked interpenetrating network structure, ensuring high bonding strength during the initial hot pressing of the product, and the polysulfide backbone structure can also ensure the flexibility and impact resistance of the adhesive layer after curing. At the same time, the silane-modified polyolefin resin can further react with moisture to crosslink to achieve the purpose of post-stage reaction curing, improving the heat resistance, hydrolysis resistance, acid and alkali resistance, and low gas permeability of the sealing frame product.

[0064] It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A post-curing acid- and alkali-resistant sealing frame, characterized in that: It includes a release layer, a post-curing hot melt adhesive layer and a substrate layer which are arranged in sequence; The post-curing hot melt adhesive layer is composed of acid-modified polyolefin resin, sulfur-containing epoxy resin, polyester resin, silane-modified polyolefin resin, curing agent and organic solvent in a weight ratio of 100: (1-5): (5-10): (10-20): (0.5-5): (40-200).

2. A post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The acid-modified polyolefin resin is modified from one of maleic anhydride and acrylic acid; The acid-modified polyolefin resin is a non-chlorinated acid-modified polyolefin resin, has a weight average molecular weight of 500,000 to 1,000,000, and an acid value of 2 to 50 mgKOH / g.

3. A post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The sulfur-containing epoxy resin is a polysulfide-modified epoxy resin with a polysulfide skeleton as the main chain.

4. A post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The polyester resin is a carboxyl-terminated hyperbranched polyester resin with a molecular weight of 1000-15000 g / mol and a branching degree of 50-80%.

5. The post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The silane-modified polyolefin resin is an amorphous-a-polyolefin containing siloxane.

6. The post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The curing agent is one of an isocyanate curing agent and a carbodiimide curing agent, wherein the mass ratio of carbodiimide to epoxysilane coupling agent in the carbodiimide curing agent is 1:0.5-0.

7.

7. The post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The organic solvent is any one of ethyl acetate, acetone, butanone, cyclohexanone, methyl isobutyl ketone, toluene, xylene, cyclohexane or a mixed solution thereof.

8. The post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The release layer is a grid release film or a matte release film with a grid shape, and the thickness of the release layer is 25-100 μm.

9. The post-curing acid- and alkali-resistant sealing frame according to claim 1, characterized in that: The substrate layer is one of PPS material or PPSU material, the thickness of the substrate layer is 25-250 μm, and the surface of the substrate layer is subjected to corona treatment before use so that its dyne value is ≥40; The thickness of the post-curing hot melt adhesive layer is 10-40 μm.

10. A method for preparing a post-cured acid- and alkali-resistant sealing frame according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Preparation of post-curing hot melt adhesive Add an acid-modified polyolefin resin and an organic solvent into an autoclave, dissolve them at 60°C, then heat them up to 70°C, add a sulfur-containing epoxy resin, a polyester resin and a silane-modified polyolefin resin, continue stirring and dissolving at 70-80°C, perform ultrasonic-assisted dispersion at 20-40kHz to eliminate bubbles, cool them to room temperature after they are completely dissolved, filter and pour them out, and obtain a post-cured hot melt adhesive; S2. Preparation of post-curing hot melt adhesive layer The post-cured hot melt adhesive prepared in step S1 is added with a curing agent and stirred evenly, filtered through a 200-800 mesh filter or a 1-20 μm filter element, and then coated on the substrate layer using a scraper coater or a CED coater, dried at 80-150° C. for 3-10 minutes, and then attached with a release layer to prepare a post-cured acid- and alkali-resistant sealing frame.

Images