Damp-heat-resistant sealing material for hydrogen fuel cell and preparation method of sealing material

Abstract

The invention belongs to the technical field of fuel cells, and particularly relates to a sealing material for a damp-heat-resistant hydrogen fuel cell and a preparation method of the sealing material for the damp-heat-resistant hydrogen fuel cell. 5 to 30 parts of amorphous polyester; 10 to 20 parts of epoxy resin; 1 to 5 parts of a polyhydroxyalkene oligomer; 0.5 to 3.0 parts of a closed type cross-linking agent; 10-20 parts of an inorganic filler; 0.5 to 1.0 part of an anti-hydrolysis agent; 0.5 to 2.0 parts of an antioxidant; and 0.5 to 2.0 parts of a coupling agent. The sealing material has good initial adhesiveness and final adhesiveness, and excellent resistance to damp-heat deterioration.

Description

Technical Field

[0001] The present invention relates to a sealing material for a hydrogen fuel cell resistant to heat and humidity and a preparation method thereof, belonging to the technical field of fuel cells. Background Art

[0002] A fuel cell is a system that directly converts the chemical energy of a fuel gas into electrical energy. Due to its advantages such as high conversion efficiency and no emissions, it has received extensive attention and use. Hydrogen gas generates protons and electrons under the action of a catalyst on the anode plate. The protons pass through the proton exchange membrane and reach the cathode of the fuel cell. The electrons cannot pass through the proton exchange membrane and reach the cathode plate of the fuel cell through an external circuit, thereby generating an electric current in the external circuit. Since the hydrogen gas molecule has a small diameter, leakage is likely to cause combustion and explosion. Therefore, it is required that the battery unit has good gas tightness, especially the external sealing effect of the stack between the membrane electrode and the bipolar plate should be good. Most of the existing technologies use unsaturated polyolefin rubber or tapes or films with a multi-layer structure as sealing materials. The Chinese invention patent application with the application number 202010614192.0 discloses a sealing material for a fuel cell and a preparation method thereof. The unsaturated rubber used therein requires high-temperature vulcanization, has poor resistance to strong acids, and has poor adhesion to various metals and inorganic materials. During long-term use, the interfacial adhesion is likely to fail due to the action of warm water immersion. The Chinese invention patent with the application number 201410014082.5 discloses a fuel cell sealing material and a preparation method thereof. The multi-layer structure used therein is a tape composite elastic sealing rubber layer, with a complex material structure, a cumbersome preparation process, and difficult cost control. The Chinese invention patent application with the application number 202080067157.X discloses a fuel cell bonding body and a laminate, which is also a multi-layer structure sealing material. The adhesive resin layer uses an acid-modified polyolefin adhesive resin. The easy-bonding layer is first coated on both sides of the substrate as a primer layer, and then the adhesive resin is coated, with a complex preparation process. Summary of the Invention

[0003] In view of the above problems of the prior art, the present invention provides a sealing material for a hydrogen fuel cell resistant to heat and humidity and a preparation method thereof. The sealing material has good initial adhesiveness and excellent long-term resistance to heat and humidity deterioration.

[0004] The technical solution for the present invention to solve the above technical problems is as follows:

[0005] A sealing material for a hydrogen fuel cell resistant to heat and humidity, the raw materials of which include the following components in parts by weight: 30-70 parts of crystalline polyester; 5-30 parts of non-crystalline polyester; 10-20 parts of epoxy resin; 1-5 parts of polyhydroxyolefin oligomer; 0.5-3.0 parts of blocked crosslinking agent; 10-20 parts of inorganic filler; 0.5-1.0 hydrolysis inhibitor; 0.5-2.0 parts of antioxidant; 0.5-2.0 parts of coupling agent.

[0006] On the basis of the above technical solutions, the present invention can also be improved as follows:

[0007] Further, the molecular weight of the crystalline polyester is 20,000 - 35,000, and the melting point is 90 - 130 °C; preferably, commercially available crystalline polyesters such as VYLON GM-913 and GM-995 produced by Toyobo can be selected.

[0008] The beneficial effects of adopting the above technical solutions are as follows: In the crystalline region of the crystalline polyester resin, the molecular arrangement is neat and dense, making it not easily attacked and not easily hydrolyzed. The melting temperature of the crystalline form cannot be too high. Since high temperature is required during lamination bonding, a resin with a melting point less than 130 °C can be selected. When hydrogen and oxygen in the fuel cell react to generate water and heat, the bonding material is in a high-temperature and high-humidity environment for a long time. Therefore, the melting point of the crystalline polyester needs to be at least greater than 90 °C, preferably 100 - 130 °C. The crystalline polyester provides the body strength and initial adhesiveness of the material in the sealing material.

[0009] Further, the molecular weight of the amorphous polyester is 10,000 - 30,000, and the glass transition temperature > 50 °C. Preferably, commercially available amorphous polyesters such as VYLON 200 and VYLON 290 produced by Toyobo can be selected.

[0010] The beneficial effects of adopting the above technical solutions are as follows: When the amorphous polyester resin is tested by differential scanning calorimetry (DSC), it does not have a crystal melting peak. Its polymer chains are arranged in a messy and entangled manner without forming an orderly arrangement structure. During the solidification process, there is no crystal nucleus and crystal grain growth process, only the phenomenon that free polymer chains are "frozen". The addition of the amorphous resin can reduce the hardness of the sealing material, relieve the stress generated when the hydrogen fuel cell moves or is heated, and prevent the sealing material from peeling off and failing from the bonded parts.

[0011] Further, the usage ratio of the crystalline polyester to the amorphous polyester is 2 - 3:1. If the ratio of the crystalline polyester to the amorphous polyester > 3:1, the body strength of the sealing material is hard, and the effect of resisting the stress generated by humidity and vibration is poor, manifested as the failure of the bonding interface; if the ratio is less than 2:1, the initial adhesiveness of the sealing material is poor, and the free movement of the amorphous resin causes bonding failure when soaked in hot water.

[0012] Further, the epoxy resin is a solid bisphenol type epoxy resin with a softening point of 80 - 110 °C and an epoxy equivalent of 450 - 900 g / eq. By adding the epoxy resin, the body strength after curing can be improved, the adhesiveness after thermal lamination can be improved, and the resistance to humidity and heat aging can be improved.

[0013] Furthermore, the polyhydroxyolefin oligomer has a saturated hydrocarbon backbone, multiple hydroxyl groups, and a number average molecular weight range of 1000 to 3000. As a preferred polyhydroxyolefin oligomer, it can be selected from POLYTAIL produced by Mitsubishi Chemical Corporation. The hydroxyl group is reactive with isocyanate, and can provide thermal stability and water resistance after curing.

[0014] Furthermore, the blocked cross-linking agent is a blocked isocyanate cross-linking agent, which can be selected from TAKENATE XB-G282 low-temperature blocked isocyanate produced by Mitsui Chemicals, which can be unblocked at 80° C. to participate in the reaction.

[0015] Furthermore, the inorganic filler is talc, which can be selected from LMS-200 produced by Fuji Talc Industry Co., Ltd. or Luzenac 10M0 produced by Ingersoll-Mainland China.

[0016] Furthermore, the anti-hydrolysis agent is bis(2,6-diisopropylbenzene)carbodiimide, which can be selected from the anti-hydrolysis agent AW-700 produced by Guangzhou Yinyuan.

[0017] Furthermore, the coupling agent is a silane coupling agent or a titanate coupling agent, and the silane coupling agent KH-560 or the titanate coupling agent KR-TTS produced by Kenrich in the United States can be selected.

[0018] Furthermore, the antioxidant is a hindered phenol and phosphite composite antioxidant BASF Irganox B215.

[0019] The present invention also provides a method for preparing the above-mentioned heat-resistant hydrogen fuel cell sealing material, wherein the raw materials are prepared into a slurry, and the slurry is coated on a substrate film with a thickness of 25 to 125 μm, and the coating thickness is 15 to 300 μm to obtain the sealing material. Specifically, the method comprises the following steps:

[0020] (1) Weighing 30-70 parts of crystalline polyester, 5-30 parts of non-crystalline polyester, 10-20 parts of epoxy resin, 1-5 parts of polyhydroxyolefin oligomer, 10-20 parts of inorganic filler, 0.5-1.0 parts of anti-hydrolysis agent, 0.5-2.0 parts of antioxidant, and 0.5-2.0 parts of coupling agent as raw materials by weight, adding the above raw materials into a three-necked flask and dissolving them with toluene solvent, heating them in a water bath to 80° C., stirring and mixing until they are completely dissolved, cooling the mixed solution to below 30° C., adding 0.5-3 parts of blocked isocyanate crosslinking agent, continuing to stir and mix evenly, and preparing a slurry with a solid content of 15 to 30 wt %;

[0021] (2) Add the above slurry to a comma coater. At the same time, place the substrate film on the unwind unit of the comma coater, put it into the corona treatment machine for corona treatment, coat the above slurry on the corona side of the substrate film, and dry it. The drying temperature is set at 40-60 °C. After drying for 10 minutes, laminate a release film and wind it up to obtain the finished product.

[0022] The present invention does not specifically limit the type of the substrate film. Preferably, the substrate film material can be selected from materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyamide (PA), thermoplastic polyurethane (TPU), etc. Considering parameters such as physical and mechanical properties, gas barrier properties, chemical stability, heat resistance stability, surface coating properties, etc. comprehensively, and for the convenience of describing the technical solution of the present invention, more preferably, the present invention uses PEN material as the substrate film.

[0023] The advantages of the present invention are as follows:

[0024] (1) The raw materials used in the sealing material for hydrogen fuel cells of the present invention are easily obtained and the manufacturing process is simple;

[0025] (2) The sealing material of the present invention has excellent initial adhesion, final adhesion performance, and resistance to wet heat deterioration. Specific Embodiments

[0026] The following further describes the present invention in detail with reference to embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0027] Raw materials used in the examples:

[0028] A1: Crystalline polyester, VYLON GM-913 produced by Toyobo;

[0029] A2: Crystalline polyester, VYLON GM-995 produced by Toyobo;

[0030] B1: Amorphous polyester, VYLON 200 produced by Toyobo;

[0031] B2: Amorphous polyester, VYLON 290 produced by Toyobo;

[0032] C: Epoxy resin, E-20 (CYD-011) produced by Baling Petrochemical;

[0033] D: Polyhydroxyolefin oligomer, POLYTAIL H produced by Mitsubishi Chemical;

[0034] E: Isocyanate crosslinking agent, TAKENATE XB-G282 produced by Mitsui Chemicals;

[0035] F: Inorganic filler, talc Luzenac 10M0 produced by Imerys;

[0036] G: Hydrolysis inhibitor: carbodiimide hydrolysis inhibitor AW-700 produced by Guangzhou Yinyuan;

[0037] H: Titinate coupling agent, Kenrich KR-TTS from the United States;

[0038] I: Compound antioxidant, Irganox B215 from BASF;

[0039] Example 1

[0040] This example prepares a moisture and heat resistant sealing material for hydrogen fuel cells, which is prepared from the following raw materials in parts by weight: crystalline polyester (A1) 45 g; amorphous polyester (B1) 15 g; epoxy resin (C) 15 g; polyhydroxyolefin oligomer (D) 5 g; talc (F) 15 g; hydrolysis inhibitor (G) 1 g, coupling agent (H) 1 g, antioxidant (I) 1 g;; 400 g of toluene solvent; Add the above raw materials to a 1000 mL three-necked flask, heat in a water bath to 80 °C, stir and mix until completely dissolved, cool the mixed solution to below 30 °C, add 2 g of blocked isocyanate crosslinking agent (E), and continue to stir and mix evenly to obtain a sealing material solution with a solid content of 20%.

[0041] Then coat the prepared sealing material on a 25 μm PEN film, with a dry coating thickness of 15 μm, and dry it in an oven at 50 °C to obtain the sealing material product.

[0042] Example 2

[0043] The dry coating thickness is 100 μm, and the addition amounts of other raw materials and the production process are the same as those in Example 1.

[0044] Example 3

[0045] Use a 125 μm PEN film substrate for coating, and the addition amounts of other raw materials, coating thickness and production process are the same as those in Example 1.

[0046] The addition amounts of various raw materials in Examples 4 to 9 are shown in Table 1, and the coating thickness and production process are the same as those in Example 1.

[0047] The addition amounts of various raw materials in Comparative Examples 1 to 5 are shown in Table 2, and the coating thickness and production process are the same as those in Example 1.

[0048] We tested the performance of the sealing material products obtained in Examples 1 to 9 and Comparative Examples 1 to 5. The test methods are as follows:

[0049] 1) Peel strength test:

[0050] The test substrates were aluminum plates (1 mm thick), stainless steel plates (1 mm thick), and PEN films (125 μm, surface energy > 48 dynes / cm). Samples were prepared using a flat hot press. The hot pressing conditions were 140 °C / 0.6 MPa / 30 s. After sample preparation, the samples were cooled to 25 °C and left standing for 24 h. The 180° peel strength test was carried out according to the method described in the national standard GB / T 2792-2014. The test conditions were a temperature of 25 °C, a tensile rate of 300 mm / min, and a test width of 20 mm.

[0051] 2) Hot water immersion aging test:

[0052] Prepare test samples with an aluminum plate as the bonding substrate according to test method 1). Immerse the samples in hot water at 90 °C for 500 h and 1000 h, then observe whether there are any abnormalities such as bubbles or whitening on the bonding surface, and test the 180° peel strength.

[0053] The above test results are shown in Table 1-2:

[0054] Table 1 Performance test results of Examples 1-8

[0055]

[0056]

[0057] Table 2 Performance test results of Comparative Examples 1-5

[0058]

[0059]

[0060] Note: Appearance judgment criteria:

[0061] No bubbles, no whitening or other abnormalities, ◎

[0062] A small amount of bubbles, whitening or other abnormalities, ○

[0063] A large amount of bubbles, whitening or other abnormalities, ⅹ

[0064] As can be seen from the results shown in Comparative Example 2 in Table 2, no amorphous polyester was added in Comparative Example 1, and it was easy to penetrate into the bonding interface after hot water immersion, generating bubbles and causing the bonding interface to fail; no crystalline polyester was added in Comparative Example 2, the initial adhesiveness was poor, the bulk strength deteriorated after hot water immersion, and the colloid turned white and generated bubbles; the content of crystalline polyester was small in Comparative Example 3, and a large number of bubbles were generated after aging test and the adhesive force was low; no epoxy resin was added in Comparative Example 4, the bulk strength was weak after bonding and curing, the adhesive force to the metal interface was poor, and it turned white and generated bubbles after aging test; no polyhydroxyolefin oligomer was added in Comparative Example 5, the initial strength was excellent, but the adhesive force decreased rapidly after hot water immersion; no crosslinking agent was added in Comparative Example 6, the initial adhesive force was excellent, but the resistance to damp heat aging was poor.

[0065] As can be seen from the results shown in the examples of Table 1, the sealing material for hydrogen fuel cells provided by the present invention has good adhesive force to metals such as aluminum and stainless steel and PEN, is resistant to long-term immersion aging in hot water, has good resistance to damp heat, has a very good sealing effect, can remain stable in proton exchange membrane hydrogen fuel cells for a long time, and has certain practical value.

[0066] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sealing material for a hydrogen fuel cell resistant to damp heat, the raw materials comprising the following substances in parts by weight: 30 - 70 parts of crystalline polyester; 5 - 30 parts of amorphous polyester; 10 - 20 parts of epoxy resin; 1 - 5 parts of polyhydroxyolefin oligomer; 0.5 - 3.0 parts of blocked crosslinking agent; 10 - 20 parts of inorganic filler; 0.5 - 1.0 of hydrolysis inhibitor; 0.5 - 2.0 parts of antioxidant; 0.5 - 2.0 parts of coupling agent.

2. The moisture and heat resistant sealing material for hydrogen fuel cells according to claim 1, characterized in that, The molecular weight of the crystalline polyester is 20,000 - 35,000, and the melting point is 90 - 130 °C; the molecular weight of the amorphous polyester is 10,000 - 30,000, and the glass transition temperature > 50 °C; the usage ratio of the crystalline polyester to the amorphous polyester is 2 - 3:

1.

3. The moisture and heat resistant sealing material for hydrogen fuel cells according to claim 1, characterized in that, The epoxy resin is a solid epoxy resin with a softening point of 80 - 110 °C; the main chain of the polyhydroxyolefin oligomer is a saturated hydrocarbon backbone, with multiple hydroxyl groups, and the number average molecular weight is 1,000 - 3,000.

4. The moisture and heat resistant sealing material for hydrogen fuel cells according to claim 1, wherein The blocked crosslinking agent is a blocked isocyanate, and the deblocking temperature is 80 - 100 °C; the hydrolysis inhibitor is carbodiimide; the inorganic filler is talc powder; the coupling agent is a silane coupling agent or a titanate coupling agent; the antioxidant is composed of hindered phenols, phosphites or a complex of the two.

5. A preparation method of the sealing material for a hydrogen fuel cell according to any one of claims 1-4, characterized in that, The raw materials are formulated into a slurry, and the slurry is coated on a substrate film with a thickness of 25 - 125 μm, and the coating thickness is 15 - 300 μm to obtain the sealing material.

6. The preparation method of the sealing material for a hydrogen fuel cell according to claim 5, wherein, It includes the following steps: (1) Weigh 30 - 70 parts of crystalline polyester, 5 - 30 parts of amorphous polyester, 10 - 20 parts of epoxy resin, 1 - 5 parts of polyhydroxyolefin oligomer, 10 - 20 parts of inorganic filler, 0.5 - 1.0 of hydrolysis inhibitor, 0.5 - 2.0 parts of antioxidant, and 0.5 - 2.0 parts of coupling agent by weight. Add the above raw materials into a three-necked flask and dissolve them with toluene solvent. Heat the water bath to 80 °C, stir and mix until completely dissolved. Cool the mixed solution to below 30 °C, add 0.5 - 3 parts of blocked isocyanate crosslinking agent, and continue to stir and mix evenly to prepare a slurry with a solid content of 15 - 30 wt%. (2) Add the above slurry into a comma coater, and at the same time place the substrate film on the unwind unit of the comma coater, put it into the corona treatment machine for corona treatment. Coat the above slurry on the corona side of the substrate film, dry it, set the drying temperature at 40 - 60 °C, after drying for 10 min, laminate with a release film, and wind up to obtain the finished product.

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