JP2010146781A - Adhesive sealing member for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sealing member for a fuel cell capable of crosslinking at low temperature with high sealing properties and adhesion reliability. <P>SOLUTION: The adhesive sealing member for a fuel cell for sealing between constituent members of a fuel cell is made structured of crosslinking substances of rubber compositions including the following (A) to (D). (A) a kind or more rubber ingredients selected from ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile butadiene rubber, and hydrogen-added acrylonitrile butadiene rubber, (B) a crosslinking agent selected from organic peroxide with a one-hour half-life temperature of 130°C or less, (C) crosslinking auxiliaries, and (D) an aluminate series coupling agent alone, or an aluminate series coupling agent and an adhesive constituent consisting of both a resorcinol series compound and a melamine series compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive seal member that adhesively seals members constituting a fuel cell.

  A fuel cell that generates electricity by an electrochemical reaction of gas has high power generation efficiency, clean gas discharged, and extremely little influence on the environment. Among these, the polymer electrolyte fuel cell can be operated at a relatively low temperature and has a large power density. For this reason, various uses, such as a power generation and a power supply for automobiles, are expected.

  In a polymer electrolyte fuel cell, a cell in which an electrolyte membrane electrode assembly (MEA) is sandwiched between separators serves as a power generation unit. The MEA includes a polymer membrane (electrolyte membrane) serving as an electrolyte and a pair of electrodes (fuel electrode and oxygen electrode) disposed on both sides of the electrolyte membrane. Each of the pair of electrodes includes a catalyst layer and a gas diffusion layer. A fuel gas such as hydrogen or hydrocarbon is supplied to the fuel electrode, and an oxidant gas such as oxygen or air is supplied to the oxygen electrode. Power generation is performed by an electrochemical reaction at the three-phase interface between the supplied gas, electrolyte, and electrode. The polymer electrolyte fuel cell is configured by fastening a cell stack in which a plurality of the cells are stacked with end plates or the like disposed at both ends in the cell stacking direction.

The separator is formed with a flow path of gas supplied to each electrode and a flow path of refrigerant for relaxing heat generation during power generation. For example, when the gas supplied to each electrode is mixed, problems such as a decrease in power generation efficiency occur. The electrolyte membrane has proton conductivity in a state containing water. For this reason, it is necessary to keep the electrolyte membrane in a wet state during operation. Therefore, in order to prevent gas mixing, gas and refrigerant leakage, and to keep the inside of the cell in a wet state, a sealing property between the electrolyte membrane and the separator or between adjacent separators is secured. It becomes important. Silicone rubber, ethylene-propylene-diene rubber (EPDM) or the like is used as a sealing member for sealing between the constituent members of these fuel cells (see, for example, Patent Documents 1 and 2). On the other hand, Patent Document 3 describes that the adhesiveness between the viscoelastic resin and the metal plate is improved by adding a coupling agent to the viscoelastic resin sandwiched between the pair of metal plates. Yes.
JP 2006-244765 A JP 2002-371161 A JP-A-5-329980

  It is desirable to use a material that can be crosslinked at a lower temperature and in a shorter time for the seal member of the fuel cell. That is, normally, a polymer membrane such as a perfluorinated sulfonic acid membrane is used for the electrolyte membrane of the solid polymer fuel cell. Therefore, when the material for the seal member is arranged close to the electrolyte membrane for crosslinking, it is necessary to consider that the electrolyte membrane does not deteriorate due to heating during crosslinking. That is, it is desirable to perform the crosslinking process of the seal member at a lower temperature and in a shorter time.

  In this regard, as described in Patent Documents 2 and 3, crosslinking such as EPDM used as a sealing member is usually performed at a high temperature of 150 ° C. or higher. Specifically, according to Patent Document 2, the crosslinking temperature is about 150 to 230 ° C., and according to Patent Document 3, the crosslinking temperature is 190 ° C. or higher. If crosslinking is performed at such a high temperature, the electrolyte membrane may be deteriorated. Further, the sealing member of Patent Document 2 does not contain an adhesive component. For this reason, in order to adhere | attach a sealing member and a counterpart member, an adhesive agent is separately required.

  On the other hand, silicone rubber can be crosslinked at a relatively low temperature, and is excellent in heat resistance and cold resistance. However, when silicone rubber is used as a sealing member, there are the following problems. That is, silicone rubber has low mechanical strength and high gas permeability. Moreover, as described above, the electrolyte membrane of the solid polymer fuel cell is a polymer membrane such as a perfluorinated sulfonic acid membrane. For this reason, during operation, an acid such as hydrofluoric acid may be generated from the electrolyte membrane. However, the acid resistance of silicone rubber is not sufficient. In addition, an adhesive is separately required to bond the silicone rubber and a mating member such as a separator. Further, when the silicone rubber is crosslinked, a platinum catalyst is used. For this reason, from the viewpoint of preventing catalyst poisoning or the like, strict management of the working environment is required at the time of crosslinking.

  This invention is made | formed in view of such an actual condition, and makes it a subject to provide the adhesive sealing member for fuel cells which can be bridge | crosslinked at low temperature and has high sealing performance and adhesive reliability.

An adhesive seal member for a fuel cell of the present invention (hereinafter referred to as “adhesive seal member of the present invention” as appropriate) is composed of a crosslinked product of a rubber composition containing the following (A) to (D). The structural members are bonded and sealed.
(A) One or more rubber components selected from ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber, and hydrogenated acrylonitrile-butadiene rubber.
(B) A crosslinking agent selected from organic peroxides having a one-hour half-life temperature of 130 ° C. or lower.
(C) A crosslinking aid.
(D) An adhesive component consisting of only an aluminate coupling agent or an aluminate coupling agent, and a resorcinol compound and a melamine compound.

  In the adhesive seal member of the present invention, the rubbers listed in (A) above are used instead of silicone rubber. Since these rubbers have low gas permeability, sealing properties are improved. Here, the crosslinking of the rubbers listed in the above (A) is usually performed at a temperature of 150 ° C. or higher. However, in the adhesive seal member of the present invention, an organic peroxide having a one-hour half-life temperature of 130 ° C. or less is used as a crosslinking agent (above (B)). Here, the “half-life” is the time until the concentration of the organic peroxide becomes half of the initial value. Therefore, the “half-life temperature” is an index indicating the decomposition temperature of the organic peroxide. The “1 hour half-life temperature” is a temperature at which the half-life is 1 hour. In other words, the lower the one-hour half-life temperature, the easier it is to decompose at low temperatures. By using an organic peroxide having a one-hour half-life temperature of 130 ° C. or lower, crosslinking can be performed at a lower temperature (specifically 130 ° C. or lower) and in a short time. Therefore, for example, the adhesive seal member of the present invention can be used also in the vicinity of the electrolyte membrane of the solid polymer fuel cell. Further, according to the crosslinking agent (B), a platinum catalyst used for crosslinking of the silicone rubber is not necessary at the time of crosslinking. In addition, it is difficult to cause poor curing due to impurities, dirt, and the like. For this reason, the adhesive seal member of the present invention is not easily affected by the working environment and is easy to handle.

  Moreover, the adhesive sealing member of this invention contains an adhesive component (above (D)). Therefore, it is not necessary to use a separate adhesive for bonding with the constituent members of the fuel cell. That is, a chemical bond is formed between the rubber component (adhesive seal member) and the constituent member via the aluminate coupling agent in the adhesive component. Thereby, a rubber component and a structural member are adhere | attached. Here, the bond energy of the atoms constituting the aluminate coupling agent is large. For this reason, it is thought that an aluminate coupling agent is hard to hydrolyze compared with a silane coupling agent, for example. Therefore, it is possible to maintain the sealing performance and the adhesiveness for a longer period.

  When the resorcinol compound and the melamine compound are included as the adhesive component, the melamine compound becomes a methylene donor and the resorcinol compound becomes a methylene donor. At the time of cross-linking, donation of a methylene group forms a chemical bond between the resorcinol compound, the rubber component and the constituent member, and the rubber component and the constituent member are bonded.

  Thus, the adhesive force of the adhesive component (D) is large. Further, even in the operating environment of the fuel cell, the adhesive force is unlikely to decrease. Therefore, according to the adhesive seal member of the present invention, good sealability is ensured even when the fuel cell is operated for a long time. Thereby, the operation reliability of the fuel cell can be improved.

  Below, embodiment of the adhesive seal member for fuel cells of this invention is described. The adhesive seal member for a fuel cell of the present invention is not limited to the following embodiments, and various modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention. It can be implemented in the form.

<Adhesive seal member for fuel cell>
The adhesive sealing member of this invention consists of a crosslinked material of the rubber composition containing said (A)-(D). First, the rubber component (A) is one or more selected from ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), and hydrogenated acrylonitrile-butadiene rubber (H-NBR). It is. One of these may be used alone, or two or more may be mixed and used.

  Next, the crosslinking agent (B) is selected from organic peroxides having a one-hour half-life temperature of 130 ° C. or lower. Examples of such organic peroxides include peroxyketals, peroxyesters, diacyl peroxides, peroxydicarbonates, and the like. Among them, peroxyketals and peroxyesters having a one-hour half-life temperature of 100 ° C. or more are easy to crosslink at a temperature of about 130 ° C. and are excellent in the handleability of a rubber composition kneaded by adding a crosslinking agent. It is desirable to employ at least one of the above. In particular, a one-hour half-life temperature of 110 ° C. or higher is preferable.

  Examples of the peroxyketal include n-butyl 4,4-di (t-butylperoxy) valerate, 2,2-di (t-butylperoxy) butane, 2,2-di (4,4-di). (T-butylperoxy) cyclohexyl) propane, 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) ) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) -2-methylcyclohexane and the like. Examples of peroxyesters include t-butyl peroxybenzoate, t-butyl peroxyacetate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t -Butylperoxy 2-ethylhexyl monocarbonate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxymalein An acid, t-hexyl peroxy isopropyl monocarbonate, etc. are mentioned. Among these, 1,1-di (t-butylperoxy) cyclohexane, t-butylperoxyacetate, and t-butylperoxyisopropyl monocarbonate are preferable because the crosslinking agent can be easily stored. Especially, when t-butyl peroxyisopropyl monocarbonate is used, crosslinking can be performed in a shorter time.

  In order to sufficiently advance the crosslinking reaction, the amount of the crosslinking agent is desirably 1 part by weight or more with respect to 100 parts by weight of the rubber component (A). In addition, considering the storage stability of the prepared rubber composition, it is desirable to be 5 parts by weight or less.

  Next, what is necessary is just to select a crosslinking adjuvant (C) suitably according to the kind of said crosslinking agent (B). Examples of the crosslinking aid include maleimide compounds, triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and trimethylolpropane trimethacrylate (TMPT). Among these, it is desirable to use a maleimide compound because the crosslinking rate becomes faster. In this case, in order to allow the crosslinking reaction to proceed sufficiently, the amount of the crosslinking aid is desirably 0.1 parts by weight or more with respect to 100 parts by weight of the rubber component (A). On the other hand, if the blending amount of the crosslinking aid is large and the crosslinking speed is too high, the adhesive strength is reduced. Therefore, the blending amount of the crosslinking aid is desirably 3 parts by weight or less.

  Next, the adhesive component (D) is composed of only the aluminate coupling agent or both the aluminate coupling agent and the resorcinol compound and the melamine compound. That is, as an adhesive component, only an aluminate coupling agent may be used, and a resorcinol compound and a melamine compound may be added to the aluminate coupling agent. When both an aluminate coupling agent and a resorcinol compound and a melamine compound are used, the adhesive force is further improved.

  The aluminate coupling agent may be appropriately selected from an aluminum organic compound having a hydrolyzable alkoxy group and a portion having an affinity for the rubber component in consideration of adhesiveness and the like. For example, aluminum alkyl acetoacetate diisopropylate, aluminum ethylacetoacetate diisopropylate, aluminum trisethylacetoacetate, aluminum isopropylate, aluminum diisopropylate monosecondary butyrate, aluminum secondary butyrate, aluminum ethylate, aluminum bis Examples include ethyl acetoacetate monoacetylacetonate, aluminum trisacetylacetonate, aluminum monoisopropoxymonooroxyethyl acetoacetate, and the like. One of these may be used alone, or two or more may be mixed and used. Of these, aluminum alkyl acetoacetate / diisopropylate, aluminum ethylacetoacetate / diisopropylate, and aluminum trisethylacetoacetate are preferable.

  In order to obtain a desired adhesive strength, the amount of the aluminate coupling agent is desirably 0.5 parts by weight or more with respect to 100 parts by weight of the rubber component (A). More preferably, it is 2 parts by weight or more. Excessive blending also causes a decrease in the physical properties of the rubber and there is a risk that the processability will also decrease. For this reason, the compounding amount of the aluminate coupling agent is desirably 10 parts by weight or less. It is more preferable if it is 6 parts by weight or less.

Examples of the resorcinol compound include resorcin, modified resorcin / formaldehyde resin, resorcin / formaldehyde (RF) resin, and the like. One of these may be used alone, or two or more may be mixed and used. Among these, a modified resorcin / formaldehyde resin is preferable in that it has low volatility, low hygroscopicity, and excellent compatibility with rubber. Examples of the modified resorcin / formaldehyde resin include those represented by the following general formulas (1) to (3). In particular, those represented by the general formula (1) are suitable.

  In order to obtain a desired adhesive strength, the amount of the resorcinol compound is desirably 0.1 parts by weight or more with respect to 100 parts by weight of the rubber component (A). It is more suitable when it is 0.5 parts by weight or more. Further, since excessive blending causes a decrease in the physical properties of the rubber, the blending amount of the resorcinol compound is desirably 10 parts by weight or less. More preferably, it is 5 parts by weight or less.

Examples of the melamine compound include methylated formaldehyde / melamine polymer, hexamethylenetetramine, and the like. One of these may be used alone, or two or more may be mixed and used. These decompose under heating during crosslinking and supply formaldehyde to the system. Of these, a methylated product of formaldehyde / melamine polymer is preferred because it has low volatility, low hygroscopicity, and excellent compatibility with rubber. As the methylated formaldehyde / melamine polymer, for example, those represented by the following general formula (4) are suitable. In particular, in the general formula (4), a mixture in which n = 1 is 43 to 44% by weight, n = 2 is 27 to 30%, and n = 3 is 26 to 30% by weight is preferable. .

  The compounding ratio of the resorcinol compound and the melamine compound is preferably in the range of 1: 0.5 to 1: 2 by weight. A range of 1: 0.77 to 1: 1.5 is more preferred. When the compounding ratio of the melamine compound to the resorcinol compound is less than 0.5, there is a tendency that the tensile strength, elongation and the like of the rubber are slightly reduced. On the other hand, when the blending ratio of the melamine compound exceeds 2, the adhesive force is saturated. For this reason, the compounding beyond it leads to a cost increase.

  When using both an aluminate coupling agent and a resorcinol compound and a melamine compound as the adhesive component (D), the total compounding amount is 100 parts by weight of the rubber component (A). It is desirable that the amount be 1 part by weight or more. More preferably, it is 3 parts by weight or more. On the contrary, it is desirable that the total blending amount of both is 10 parts by weight or less. More preferably, it is 7 parts by weight or less.

  The rubber composition constituting the adhesive seal member of the present invention may contain various additives usually used as additives for rubber in addition to the above (A) to (D). For example, it is desirable to include carbon black as a reinforcing agent. The grade of carbon black is not particularly limited, and may be appropriately selected from SAF class, ISAF class, HAF class, MAF class, FEF class, GPF class, SRF class, FT class, MT class, and the like. In order to obtain the desired durability, the blending amount of carbon black is desirably 30 parts by weight or more with respect to 100 parts by weight of the rubber component (A). In consideration of ease of kneading, molding processability, etc., the amount of carbon black is preferably 150 parts by weight or less.

  Other additives include softeners, plasticizers, anti-aging agents, tackifiers, processing aids, and the like. Softeners include petroleum oils such as process oil, lubricating oil, paraffin, liquid paraffin and petrolatum, fatty oil softeners such as castor oil, linseed oil, rapeseed oil and coconut oil, tall oil, sub, beeswax , Waxes such as carnauba wax and lanolin, linoleic acid, palmitic acid, stearic acid, lauric acid and the like. The blending amount of the softening agent is preferably up to about 40 parts by weight with respect to 100 parts by weight of the rubber component (A). Examples of the plasticizer include organic acid derivatives such as dioctyl phthalate (DOP) and phosphoric acid derivatives such as tricresyl phosphate. The blending amount of the plasticizer is preferably up to about 40 parts by weight with respect to 100 parts by weight of the rubber component (A), like the softener. Moreover, as an anti-aging agent, a phenol type, an imidazole type, a wax, etc. are mentioned, It is good to mix | blend about 0.5-10 weight part with respect to 100 weight part of the said rubber component (A).

  The rubber composition can be prepared by mixing the above (A) to (D) and various additives as necessary. For example, each material other than the crosslinking agent (B), the crosslinking assistant (C), and the adhesive component (D) is premixed and then kneaded at 80 to 140 ° C. for several minutes. After cooling the kneaded product, a crosslinking agent (B), a crosslinking aid (C), and an adhesive component (D) are added, and rolls such as an open roll are used, and a roll temperature is 40 to 70 ° C. for 5 to 30 minutes. It can be prepared by kneading. In addition, you may mix | blend an adhesive component (D) in the stage of preliminary mixing.

  The prepared rubber composition is placed between components to be adhesively sealed and crosslinked. By crosslinking, the rubber composition becomes the adhesive seal member of the present invention. Here, the crosslinking temperature is desirably 130 ° C. or lower. The crosslinking time is desirably 20 minutes or less. By performing crosslinking at a low temperature for a short time, for example, the adhesive seal member of the present invention can be used also in the vicinity of the electrolyte membrane of a polymer electrolyte fuel cell.

  The prepared rubber composition is desirably molded into a predetermined shape. For example, if it is formed into a film shape, the constituent members can be easily bonded to each other by affixing and crosslinking the film-like rubber composition on the constituent members of the fuel cell. Moreover, the complicated alignment conventionally performed becomes unnecessary and it becomes easy to perform continuous processing. Furthermore, if a film-like rubber composition is laminated on the constituent members in advance, adhesion processing becomes easier. Moreover, it is also possible to integrally mold the structural member such as the MEA or the frame of the fuel cell and the molded body of the rubber composition by placing them in a mold and heating them.

<Application to fuel cells>
The adhesive seal member of the present invention provides an adhesive seal between the constituent members of the fuel cell. The fuel cell to be applied may be any one that operates at a temperature at which the rubber component that serves as the skeleton of the adhesive seal member of the present invention can be used. For example, a polymer electrolyte fuel cell (PEFC) (including a direct methanol fuel cell (DMFC)) is suitable.

  The part to be bonded and sealed (between constituent members) varies depending on the type and structure of the fuel cell. That is, the adhesive seal member of the present invention is required to be airtight and liquid-tight, and can be used for any part where the adhesive seal member has been used conventionally. Examples of the adhesive seal portion include a separator between the separators facing each other across the MEA, a frame supporting the MEA and the separator, and between the separators and separators constituting adjacent cells. In addition, the adhesive seal member of the present invention may be used for all parts where an adhesive seal is required in a fuel cell, or may be used for a part of a part where an adhesive seal is required. The material of the constituent member may be an inorganic material such as a metal or a carbon material, or an organic material such as a resin.

  An embodiment of a polymer electrolyte fuel cell using the adhesive seal member of the present invention will be shown below. FIG. 1 is a perspective view of a polymer electrolyte fuel cell using the adhesive seal member of the present invention. As shown in FIG. 1, the polymer electrolyte fuel cell 1 is configured by stacking a number of cells C. FIG. 2 shows a perspective view of the stacked cells C (for only three cells). FIG. 3 shows an exploded perspective view of a single cell C. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. As shown in FIGS. 2 to 4, the cell C includes an MEA 2, a separator 3, and a frame 4.

  The MEA 2 includes an electrolyte membrane 20 and a pair of electrodes 21a and 21b. The electrolyte membrane 20 has a rectangular thin plate shape. The pair of electrodes 21a and 21b has a rectangular thin plate shape. The pair of electrodes 21a and 21b are arranged on both sides with the electrolyte membrane 20 in between. The frame 4 is made of metal and has a rectangular frame shape. The frame 4 holds the periphery of the electrolyte membrane 20.

  The separator 3 is made of metal and has a rectangular thin plate shape. The separator 3 has a total of six grooves extending in the longitudinal direction. Due to the groove, the cross section of the separator 3 has an uneven shape (see FIG. 4). The separator 3 is disposed opposite to both sides of the MEA 2 (also both sides of the frame 4). A gas flow path 30 for supplying gas to the electrodes 21a and 21b is defined between the MEA 2 and the separator 3 by using an uneven shape. Further, between the separators 3 facing each other in the cell C adjacent to each other in the stacking direction, a refrigerant flow path 31 for flowing a refrigerant is defined using an uneven shape.

  The adhesive seal member 5 (adhesive seal member of the present invention) is disposed between the electrolyte membrane 20 and the frame 4. Further, a conventional silicone rubber seal member 6 is disposed between the frame 4 and the separator 3 and between the separators 3 facing each other in the cell C adjacent in the stacking direction.

  During operation of the polymer electrolyte fuel cell 1, fuel gas and oxidant gas are supplied through the gas flow paths 30. Here, the electrolyte membrane 20 and the frame 4 are adhesively sealed by the adhesive seal member 5. Since the gas permeability of the adhesive seal member 5 is small, gas mixing and leakage do not occur. Further, the wet state of the electrolyte membrane 20 is also maintained. In addition, in the case of the adhesive seal member 5, crosslinking can be performed at a low temperature of about 130 ° C. and in a short time. Therefore, there is little possibility that the electrolyte membrane 20 will deteriorate at the time of crosslinking. Further, the adhesiveness of the adhesive seal member 5 is not easily lowered even in the operating environment of the polymer electrolyte fuel cell 1. For this reason, at the time of an operation | movement, the favorable sealing performance by the adhesive seal member 5 is ensured. Therefore, the polymer electrolyte fuel cell 1 can be stably operated over a long period of time.

  In the present embodiment, the conventional silicone rubber seal member 6 is disposed between the frame 4 and the separator 3 and between the separators 3 facing each other in the cell C adjacent in the stacking direction. However, the adhesive seal member of the present invention may be applied to these parts. That is, in addition to the gap between the electrolyte membrane 20 and the frame 4, the adhesive seal member 5 is interposed between the frame 4 and the separator 3 or between the separators 3 facing each other in the cell C adjacent in the stacking direction. You may arrange. If it carries out like this, the gas permeability of a seal part will become small and seal nature will improve more. In addition, since it is difficult to be affected by the working environment at the time of cross-linking, the occurrence of poor curing and the like is reduced. Further, it is not necessary to use a separate adhesive to bond the adhesive seal member 5 and the constituent members such as the separator 3.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(1) Preparation of rubber composition The raw materials shown in the following Table 1 were blended to prepare each rubber composition of Examples and Comparative Examples. In Table 1, the following were used for each raw material. The sealing member of Comparative Example 1 is a conventional silicone rubber (“TSE3777” manufactured by Momentive Performance Materials Japan GK).
(A) Rubber component EPDM: “JSR EP27” manufactured by JSR Corporation, EPM: “EP11” manufactured by JSR Corporation, NBR: “Nipol (registered trademark) DN101” manufactured by Zeon Corporation.
(B) Cross-linking agent peroxyketal: “Perhexa (registered trademark) C40” manufactured by NOF Corporation (1,1-di (t-butylperoxy) cyclohexane, 1 hour half-life temperature = 111 ° C.). In addition, the compounding quantity of a crosslinking agent is not a value in the diluted state but a value when the organic peroxide is 100%.
(C) Crosslinking assistant maleimide compound: “Barunok (registered trademark) PM” manufactured by Ouchi Shinsei Chemical Co., Ltd.
(D) Adhesive component resorcinol compound: “Tacchiol (registered trademark) 620” manufactured by Taoka Chemical Co., Ltd., melamine compound: “Sumikanol (registered trademark) 507A” manufactured by Sumitomo Chemical Co., Ltd., aluminate coupling Agent (A): Kawaken Fine Chemical Co., Ltd. “aluminum chelate M” (aluminum alkyl acetoacetate diisopropylate), aluminate coupling agent (b): “ALCH” (aluminum ethyl acetoacetate di Isopropylate), aluminate coupling agent (C): “ALCH-TR” (aluminum trisethylacetoacetate) manufactured by the same company.
(E) Other additive carbon black (HAF grade): “Show Black (registered trademark) IP200” manufactured by Cabot Japan Co., Ltd., paraffinic process oil: “Diana (registered trademark) process oil PW380 manufactured by Idemitsu Kosan Co., Ltd. "

  First, in Table 1, the rubber component (A), carbon black, and paraffinic process oil were kneaded at 120 ° C. for 5 minutes using a Banbury mixer. After cooling the kneaded product, a crosslinking agent (B), a crosslinking assistant (C), and an adhesive component (D) are appropriately added, and kneaded at 50 ° C. for 10 minutes using an open roll to obtain a rubber composition. It was. The obtained rubber composition was molded into a flat plate having a predetermined thickness by pressing.

(2) Manufacture of seal member and evaluation of mechanical strength The rubber compositions of Examples 1 to 5 and Comparative Example 1 were crosslinked by holding at 130 ° C. for 20 minutes to obtain a seal member. The seal members of Examples 1 to 5 are included in the adhesive seal member of the present invention (the same applies hereinafter). In addition, in the case of the silicone rubber of the comparative example 1, it crosslinked at 130 degreeC using the catalyst which consists of a platinum compound.

About each sealing member of Examples 1-5 and Comparative Example 1, tensile strength (tensile stress at the time of cutting: T _sb ) and elongation rate (elongation at the time of cutting: E _b ) were measured. Measurement of tensile strength and elongation was performed in accordance with JIS K6251 (2004). The shape and dimensions of the test piece were dumbbell-shaped No. 5. The results are summarized in Table 1 above. In Table 1, the ratio of the tensile strength of each sealing member when the tensile strength of the silicone rubber of Comparative Example 1 is set as a standard (100) is shown as a strength index.

  As shown in Table 1, the tensile strengths of the seal members of Examples 1 to 5 were equal to or higher than the tensile strength of the silicone rubber of Comparative Example 1. Moreover, the elongation rate of the sealing member of Examples 1-5 became larger than the elongation rate of the silicone rubber of the comparative example 1. From this result, it can be seen that the adhesive seal member of the present invention is more flexible and has higher mechanical strength than conventional silicone rubber.

(3) Manufacture of seal member and evaluation of adhesiveness A 90 ° peel test based on JIS K6256-2 (2006) was performed, and the adhesiveness of each of the seal members of Examples 1 to 5 and Comparative Example 1 was evaluated. First, a flat rubber composition having a width of 25 mm, a length of 60 mm, and a thickness of 5 mm was placed on the surface of a stainless steel plate having a width of 25 mm, a length of 60 mm, and a thickness of 2 mm. Subsequently, while pressing from the rubber composition side, it was held at 130 ° C. for 20 minutes to crosslink and bond, thereby preparing a test piece. In addition, in the case of the silicone rubber of the comparative example 1, it crosslinked at 130 degreeC using the catalyst which consists of a platinum compound. Adhesion to the stainless steel plate was performed by applying an adhesive. Next, the produced test piece was attached to a predetermined test jig, and a 90 ° peel test was performed. In addition, in order to evaluate the adhesion reliability of each seal member, an environmental resistance test was performed on each test piece, and then a 90 ° peel test was performed in the same manner as described above. The environmental resistance test was performed by immersing each test piece in 90 ° C. warm water for 100 hours. And the ratio of the peeling strength of each sealing member when the initial peeling strength of the silicone rubber of Comparative Example 1 was used as a reference (100) was calculated. Table 1 collectively shows the strength index of the peel strength of each test piece in the 90 ° peel test.

  As shown in Table 1, in each of the sealing members of Examples 1 to 5, the peel strength was very large as compared with the silicone rubber of Comparative Example 1. Thus, in the sealing members of Examples 1 to 5, the crosslinking reaction sufficiently progressed even when the crosslinking was performed at a low temperature of 130 ° C., and a large adhesive force was expressed. In particular, in the seal member of Comparative Example 1, the peel strength after the environmental resistance test is smaller than that in the initial stage, whereas the peel strength of the seal members of Examples 1 to 5 is Was almost unchanged. From this result, it can be seen that the seal members of Examples 1 to 5 are less likely to have a reduced adhesive force even when used for a long time in an operating environment of a fuel cell in contact with warm water or steam. That is, it was confirmed that the adhesive seal member of the present invention has high adhesion reliability.

(4) Application to solid polymer fuel cells Using the rubber compositions of Examples 1 to 5, solid polymer fuel cells were produced. That is, first, the rubber compositions of Examples 1 to 5 were disposed between the electrolyte membrane 20 and the frame 4 as shown in FIG. Subsequently, it was held at 130 ° C. for 20 minutes for crosslinking and adhesion. That is, the electrolyte membrane 20 and the frame 4 were bonded and sealed with the seal members of Examples 1 to 5. Thereafter, the polymer electrolyte fuel cell was operated for 24 hours, and the sealing performance of each sealing member was confirmed. As a result, neither gas mixing nor leakage occurred, and it was confirmed that good adhesion was ensured.

1 is a perspective view of a polymer electrolyte fuel cell using an adhesive seal member of the present invention. It is a perspective view of the laminated | stacked cell. It is a disassembled perspective view of a single cell. It is IV-IV sectional drawing of FIG.

Explanation of symbols

1: Solid polymer fuel cell 2: MEA 20: Electrolyte membrane 21a, 21b: Electrode 3: Separator 30: Gas flow path 31: Refrigerant flow path 4: Frame 5: Adhesive seal member 6: Seal member C: Cell

Claims (7)

An adhesive seal member for a fuel cell, comprising a cross-linked product of a rubber composition containing the following (A) to (D), wherein the fuel cell components are adhesively sealed.
(A) One or more rubber components selected from ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber, and hydrogenated acrylonitrile-butadiene rubber.
(B) A crosslinking agent selected from organic peroxides having a one-hour half-life temperature of 130 ° C. or lower.
(C) A crosslinking aid.
(D) An adhesive component consisting of only an aluminate coupling agent or an aluminate coupling agent, and a resorcinol compound and a melamine compound.   2. The adhesive seal member for a fuel cell according to claim 1, wherein the organic peroxide (B) includes a peroxyketal and a peroxyester.   The amount of the crosslinking agent (B) is 1 part by weight or more and 5 parts by weight or less based on 100 parts by weight of the rubber component (A). Seal member. The crosslinking aid (C) includes a maleimide compound,
The amount of the crosslinking aid is 0.1 to 3 parts by weight based on 100 parts by weight of the rubber component (A). Adhesive seal member.   The fuel cell adhesive seal member according to any one of claims 1 to 4, wherein the adhesive component (D) comprises both an aluminate coupling agent, and a resorcinol compound and a melamine compound. .   The total amount of the aluminate coupling agent, the resorcinol compound and the melamine compound is 1 part by weight or more and 10 parts by weight or less based on 100 parts by weight of the rubber component (A). Item 6. An adhesive seal member for a fuel cell according to Item 5.   The adhesive seal member for a fuel cell according to any one of claims 1 to 6, further comprising carbon black as a reinforcing agent.

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