JP6190608B2 - Fuel cell seal - Google Patents

Description

The present invention uses a component for a fuel cell, such as a metal separator, and a rubber member for sealing it, the rubber composition of the liquid used for the adhesive layer of the fuel cell sealing member formed by bonding with an adhesive layer This relates to a fuel cell seal body.

  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 an automotive power source, are expected.

  In a polymer electrolyte fuel cell, a cell in which a membrane electrode assembly (MEA) or the like is sandwiched between metal separators is a power generation unit. The MEA is composed of a polymer membrane (electrolyte membrane) serving as an electrolyte and a pair of electrode catalyst layers (a fuel electrode (anode) catalyst layer and an oxygen electrode (cathode) catalyst layer) disposed on both sides in the thickness direction of the electrolyte membrane. Become. On the surface of the pair of electrode catalyst layers, a porous layer (gas diffusion layer) for further diffusing gas is disposed. A fuel gas such as hydrogen is supplied to the fuel electrode side, and an oxidant gas such as oxygen or air is supplied to the oxygen electrode side. Power generation is performed by an electrochemical reaction at the three-phase interface between the supplied gas, the electrolyte, and the electrode catalyst layer. The polymer electrolyte fuel cell is configured by fastening a cell laminate in which a large number of the cells are laminated with end plates or the like arranged at both ends in the cell lamination direction.

  The metal separator is formed with a flow path for gas supplied to each electrode and a flow path for refrigerant for relaxing heat generation during power generation. Moreover, since the electrolyte membrane has proton conductivity in a state containing water, 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, it is necessary to ensure sealing performance around the MEA and the porous layer and between adjacent metal separators. It becomes important. As a sealing member for sealing these constituent members, for example, an adhesive component such as a resorcinol compound is kneaded into a rubber component such as ethylene-propylene-diene rubber (EPDM), and the sealing member itself has an adhesive property to be bonded. There has been proposed an adhesive seal member for a fuel cell that does not apply an adhesive (adhesive-less) and ensures a sealing property with a constituent member such as a metal separator (Patent Document 1).

JP 2011-249283 A

  The adhesive seal member for a fuel cell described in Patent Document 1 is very excellent in terms of sealability because the adhesive component kneaded in the rubber component and the metal separator are bonded by hydrogen bonding. However, there is a problem that the adhesive component kneaded in the rubber component adheres to a general-purpose mold and the mold is contaminated. As a countermeasure, it is conceivable to use a mold with a Teflon (registered trademark) coating on the surface, but the durability is poor and the contamination of the adhesive component gradually progresses, so it is necessary to clean the mold, Automation is difficult, cost is high, and there is room for improvement in terms of mass productivity.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel cell seal body that uses a rubber composition that is free from mold contamination, is low in cost, is excellent in mass productivity, and has high adhesion reliability. And

  The inventors of the present invention have made extensive studies to obtain a rubber composition for an adhesive layer of a fuel cell sealing body that is free from mold contamination, is low in cost, is excellent in mass productivity, and has high adhesion reliability. In the course of the research, instead of kneading the adhesive component into the rubber member for sealing, a rubber member containing no adhesive component (such as vulcanized rubber) is prepared in advance, and this rubber member and fuel cell component ( Attention was paid to the application of the liquid rubber composition to at least one of the metal separator and the like, followed by adhesion. As a result, a liquid rubber composition containing an adhesive component (C) such as a rubber component (A) containing at least a liquid rubber, a crosslinking agent (B) composed of an organic peroxide, and a resorcinol compound was identified. When the adhesive layer of the fuel cell seal body is formed by using the fuel cell, the adhesion reliability of the fuel cell constituent member and the rubber member for sealing is increased, and the intended purpose can be achieved, and the present invention has been achieved.

That is, the present invention comprises a rubber member for seal metal separators, which are bonded via an adhesive layer, the membrane electrode assembly via the adhesive layer and a rubber member for seal formed by the adhesive, the film A fuel cell sealing body in which rubber members bonded to an electrode assembly are bonded to each other through an adhesive layer , and all of the adhesive layers have a thickness of 0.01 to 0.5 mm, and the following (A ) to a fuel cell sealing member non-solvent based rubber composition liquid containing is a layer formed by crosslinking the (C), the gist of it.
(A) A rubber component containing at least one solid rubber selected from the group consisting of ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber and hydrogenated acrylonitrile-butadiene rubber together with liquid rubber.
(B) A crosslinking agent comprising an organic peroxide.
(C) At least one adhesive component selected from the group consisting of a resorcinol compound, a melamine compound, an aluminate coupling agent, and a silane coupling agent.

As described above, the rubber composition according to the present invention is a liquid rubber composition used for an adhesive layer of a fuel cell seal body, and includes at least a rubber component (A) containing a liquid rubber and an organic peroxide. A liquid rubber composition (hereinafter sometimes referred to as “liquid rubber composition”) containing an adhesive component (C) such as a crosslinking agent (B) and a resorcinol compound.
In the present specification, the liquid rubber composition (liquid rubber composition) means a rubber composition that is liquid at room temperature.

  Since the liquid rubber composition contains an adhesive component (C), the adhesion between the fuel cell component and the rubber member for sealing or the adhesion between the rubber members is good, and the adhesion reliability is high. . For example, when a resorcinol compound and a melamine compound are included as the adhesive component (C), the melamine compound is a methylene donor and the resorcinol compound is a methylene donor. At the time of cross-linking, the methylene group is donated, and the resorcinol compound and the double bond of the rubber member (vulcanized rubber, etc.) are cross-linked and chemically bonded. To do. As a result, the rubber member (vulcanized rubber or the like) and the fuel cell constituent member (metal separator or the like) are bonded via the adhesive layer. When the aluminate coupling agent is included as the adhesive component (C), the fuel cell constituent member and the sealing rubber member are bonded via the aluminate coupling agent in the adhesive layer. Similarly, when a silane coupling agent is included as the adhesive component (C), the fuel cell component and the sealing rubber member are bonded via the silane coupling agent in the adhesive layer. Further, when the fuel cell component is a non-metallic material other than a metal separator, for example, a membrane electrode assembly (MEA) or a gas diffusion layer, the adhesive component (C) in the adhesive layer and the fuel cell It is considered that they are bonded to each other due to the compatibility with the structural member for use or the heat fusion force.

  The adhesive strength of these adhesive components (C) is large. In addition, even in the operating environment of the fuel cell, the adhesive force is unlikely to decrease. Therefore, according to the fuel cell seal body of the present invention, good sealing performance is ensured even when the fuel cell is operated for a long time. That is, the operation reliability of the fuel cell can be improved.

  The fuel cell seal body of the present invention has rubber elasticity in a wide temperature range from the operating temperature of the fuel cell to about −30 ° C. For this reason, according to the fuel cell seal body of the present invention, not only sealing by adhesion but also sealing by stress is possible. When rubber elasticity is lost at a very low temperature, the sealing performance is more likely to deteriorate in the stress seal than in the adhesive seal. In this regard, according to the fuel cell seal body of the present invention, the rubber elasticity is maintained even at extremely low temperatures, and therefore the sealing performance is hardly lowered even with a stress seal.

Thus, the fuel cell sealing member of the present invention, and a rubber member for components and seals for fuel cells, also the rubber members together are the liquid rubber composition containing the (A) ~ (C) Adhesion reliability is high because it is adhered by an adhesive layer. Therefore, it is not necessary to knead the adhesive component into the rubber member for sealing, and there is no mold contamination. Therefore, since there is no need to clean the mold, automation is possible, and the mass production is excellent at low cost. Moreover, in this invention, since the viscosity of a rubber composition can be lowered | hung by using liquid rubber, an adhesive layer can be easily formed by dispenser application etc., and it is excellent in working efficiency. Furthermore, since no organic solvent such as toluene is used, emission of volatile organic compounds (VOC) can be reduced, and the problem of environmental pollution can be solved.

  The ethylene-propylene rubber (EPM) and the ethylene-propylene-diene rubber (EPDM) in the specific rubber (A) are crystallized at an extremely low temperature of about −20 to −30 ° C. as the ethylene content decreases. Hateful. In other words, EPM and EPDM with a low ethylene content are less likely to have rubber elasticity even at extremely low temperatures, and therefore can maintain rubber elasticity even at extremely low temperatures. Therefore, when ethylene-propylene rubber or ethylene-propylene-diene rubber having an ethylene content of 60% by weight or less is used, the sealing performance at extremely low temperatures is further improved.

It is sectional drawing which shows an example of the fuel cell seal body of this invention.

Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.
The rubber composition of the present invention is a liquid rubber composition used for an adhesive layer of a fuel cell seal body and contains the following (A) to (C).
(A) A rubber component containing at least a liquid rubber.
(B) A crosslinking agent comprising an organic peroxide.
(C) At least one adhesive component selected from the group consisting of a resorcinol compound, a melamine compound, an aluminate coupling agent, and a silane coupling agent.

<< Specific rubber component (A) >>
The specific rubber (A) is a main component of the liquid rubber composition and usually occupies a majority of the entire liquid rubber composition.

The specific rubber component (A) needs to contain at least a liquid rubber.
In the present invention, the liquid rubber means a rubber that is liquid at room temperature and has a viscosity of 1000 Pa · s or less.

  Examples of the liquid rubber include liquid ethylene-propylene rubber (liquid EPM), liquid ethylene-propylene-diene rubber (liquid EPDM), liquid acrylonitrile-butadiene rubber (liquid NBR), and liquid hydrogenated acrylonitrile-butadiene rubber (liquid H- NBR) and the like. These may be used alone or in combination of two or more. Of these, liquid EPM and liquid EPDM are preferable in terms of sealing properties.

  The ethylene content of the liquid EPM or liquid EPDM is preferably 60% by weight or less, particularly preferably 53% by weight or less, from the viewpoint of improving the sealing property at an extremely low temperature.

The specific rubber component (A), together with the liquid rubber, rubber other than liquid rubber (hereinafter, also. Be referred to as a "solid rubber") containing.
In the present specification, the term “solid rubber” means the above “liquid rubber”, and usually means a rubber that is solid at room temperature and can be kneaded.

Examples of the solid rubber include ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), and hydrogenated acrylonitrile-butadiene rubber (H-NBR ) . One of these may be used alone, or two or more thereof may be mixed and used. Two or more similar rubbers having different Mooney viscosities may be mixed and used.

  The content of the liquid rubber is preferably 40% by weight or more, particularly preferably 60% by weight or more, most preferably 80% by weight or more of the entire specific rubber component (A) (liquid rubber + solid rubber). It is. When there is too little content of liquid rubber, the viscosity of a rubber composition will become high and the tendency for coating property to deteriorate will be seen.

The Mooney viscosity of the specific rubber component (A) is preferably 100 [ML (1 + 4) 100 ° C.] or less, and particularly preferably 60 [ML (1 + 4) 100 ° C.] or less. When the Mooney viscosity is within the above range, the fluidity of the liquid rubber composition is increased, and the coatability is improved.
In this specification, Mooney viscosity means a value measured according to JIS K6300-1 (2001).

  From the viewpoint of acid resistance and water resistance in the operating environment of the fuel cell, the specific rubber component (A) preferably contains EPDM (liquid EPDM, or liquid EPDM and solid EPDM). The EPDM diene content (diene component mass ratio) is preferably in the range of 4 to 15% by weight.

  As the diene component of the EPDM, for example, a diene monomer having 5 to 20 carbon atoms is preferable, and specifically, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl. -1,5-hexadiene, 1,4-octadiene, 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene (DCP), 5-ethylidene-2-norbornene (ENB), 5-butylidene-2-norbornene, Examples include 2-methallyl-5-norbornene and 2-isopropenyl-5-norbornene.

<< Specific cross-linking agent (B) >>
The specific crosslinking agent (B) is composed of an organic peroxide. Examples of the organic peroxide include peroxyketals, peroxyesters, diacyl peroxides, peroxydicarbonates, dialkyl peroxides, hydroperoxides, and the like. These may be used alone or in combination of two or more. Among these organic peroxides, for example, those composed of organic peroxides having a one-hour half-life temperature of 160 ° C. or less are preferably used. And in order to adhere | attach with an electrolyte membrane, it is more preferable to use the organic peroxide whose 1 hour half-life temperature is 130 degrees C or less. Further, among these, a peroxy having a one-hour half-life temperature of 100 ° C. or more is easy to crosslink at a temperature of about 130 ° C. and is excellent in the handleability of a rubber composition kneaded with a crosslinking agent. At least one of a ketal and a peroxyester is preferable, and a one-hour half-life temperature of 110 ° C. or higher is particularly preferable. Moreover, when a peroxy ester is used, crosslinking can be performed in a shorter time.

  In the present invention, the “half-life” in an organic peroxide having a one-hour half-life temperature of 160 ° C. or less in the crosslinking agent (B) means that the concentration of organic peroxide (active oxygen amount) is an initial value. Time to halve. 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 160 ° C. or less, crosslinking can be performed at a lower temperature (specifically, 150 ° C. or less) and in a short time. Therefore, for example, the fuel cell seal body of the present invention can be used also in the vicinity of the electrolyte membrane of a solid polymer fuel cell.

  Examples of the peroxyketal include n-butyl-4,4-di (t-butylperoxy) valerate, 2,2-di (t-butylperoxy) butane, and 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-hexyl) Peroxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) -2-methylcyclohexane and the like.

  Examples of the peroxyester include t-butyl peroxybenzoate, t-butyl peroxyacetate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t- Butyl peroxy-2-ethylhexyl monocarbonate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxymalein Examples thereof include acid and t-hexylperoxyisopropyl monocarbonate.

  Of these, 1,1-di (t-butylperoxy) cyclohexane, t-butylperoxyacetate, t-butylperoxyisopropyl, because the reaction with the specific rubber component (A) is relatively fast. Monocarbonate is preferred. Especially, when t-butyl peroxyisopropyl monocarbonate is used, crosslinking can be performed in a shorter time.

  The compounding amount of the specific crosslinking agent (B) (in the case of a raw material having a purity of 100%) is preferably in the range of 0.4 to 12 parts by weight with respect to 100 parts by weight of the specific rubber component (A). When the blending amount of the specific crosslinking agent (B) is too small, it tends to be difficult to sufficiently advance the crosslinking reaction. When the blending amount of the specific crosslinking agent (B) is too large, crosslinking is performed. There is a tendency that the crosslinking density rapidly rises during the reaction, leading to a decrease in adhesive strength.

<< Specific adhesive component (C) >>
As the specific adhesive component (C), at least one selected from the group consisting of a resorcinol compound, a melamine compound, an aluminate coupling agent, and a silane coupling agent is used.

  Examples of the resorcinol compound include resorcin, modified resorcin / formaldehyde resin, resorcin / formaldehyde (RF) resin, and the like. These may be used alone or in combination of two or more. Of these, a modified resorcin / formaldehyde resin is preferred 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), particularly preferably those represented by the general formula (1).

  The compounding amount of the resorcinol compound is preferably in the range of 0.1 to 30 parts by weight, particularly preferably in the range of 1 to 15 parts by weight with respect to 100 parts by weight of the specific rubber component (A). If the compounding amount of the resorcinol compound is too small, it tends to be difficult to obtain a desired adhesive force. If the compounding amount of the resorcinol compound is too large, the physical properties of the rubber tend to decrease. .

  Examples of the melamine compound include methylated formaldehyde / melamine polymer, hexamethylenetetramine, and the like. These may be used alone or in combination of two or more. These decompose under heating during crosslinking and supply formaldehyde to the system. Among these, a methylated product of formaldehyde / melamine polymer is preferable in terms of low volatility, low hygroscopicity, and excellent compatibility with rubber. As the methylated product of the above-mentioned formaldehyde / melamine polymer, for example, those represented by the following general formula (4) are preferable, in particular, in the general formula (4), the compound of n = 1 is 43 to 44% by weight, Preference is given to a mixture of 27-30% by weight of n = 2 compounds and 26-30% by weight of n = 3 compounds.

  Here, the blending ratio of the resorcinol compound and the melamine compound is preferably in the range of 1: 0.5 to 1: 2, more preferably 1: 0.77 to 1: 1.5 in terms of weight ratio. It is a range. If the blending ratio of the melamine compound is too small, the tensile strength and elongation of the rubber tend to be slightly reduced. If the blending ratio of the melamine compound is too high, the adhesive strength is saturated, so that more blending is required. Leads to cost increase.

  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 ethyl acetoacetate diisopropylate, aluminum trisethyl acetoacetate, aluminum isopropylate, aluminum diisopropylate monosecondary butyrate, aluminum secondary butyrate, aluminum ethylate, aluminum bis Examples thereof include ethyl acetoacetate monoacetylacetonate, aluminum trisacetylacetonate, aluminum monoisopropoxymonooroxyethyl acetoacetate and the like. These may be used alone or in combination of two or more. Of these, aluminum alkyl acetoacetate / diisopropylate, aluminum ethylacetoacetate / diisopropylate, and aluminum trisethylacetoacetate are preferable.

  The blending amount of the aluminate coupling agent is preferably in the range of 0.5 to 20 parts by weight, particularly preferably in the range of 3 to 15 parts by weight with respect to 100 parts by weight of the specific rubber component (A). . If the blending amount of the aluminate coupling agent is too small, it tends to be difficult to obtain the desired adhesive strength. If the blending amount of the aluminate coupling agent is too large, the physical properties of the rubber deteriorate. Tend to decrease, and the workability tends to decrease.

  The silane coupling agent may be appropriately selected from a group of compounds having an epoxy group, an amino group, a vinyl group or the like as a functional group in consideration of adhesiveness. For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxy Examples thereof include silane, 3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane. Moreover, in order to prevent volatilization, the oligomer which these compounds couple | bonded is also used. These may be used alone or in combination of two or more. In particular, when one or more compounds selected from the group of compounds having an epoxy group or a vinyl group are used, the adhesive force is improved and the adhesive force is not easily lowered even in the operating environment of the fuel cell. Specifically, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane , Vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane and the like are preferable.

  The blending amount of the silane coupling agent is preferably in the range of 0.5 to 20 parts by weight, particularly preferably in the range of 5 to 10 parts by weight with respect to 100 parts by weight of the specific rubber component (A). If the compounding amount of the silane coupling agent is too small, it tends to be difficult to obtain a desired adhesive force. If the compounding amount of the silane coupling agent is too large, the physical properties of the rubber are deteriorated and processed. There is a tendency for the sex to decline.

  In addition to the above (A) to (C), the liquid rubber composition used in the present invention includes a crosslinking aid (D), a softening agent, a reinforcing agent, a plasticizer, an antiaging agent, a tackifier, a processing agent. Various additives used in ordinary rubber compositions such as auxiliaries may be blended.

<< Crosslinking aid (D) >>
Examples of the crosslinking aid include maleimide compounds, triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and trimethylolpropane trimethacrylate (TMPT). These may be used alone or in combination of two or more. Among these, it is preferable to use a maleimide compound because the effect of improving the crosslinking density and strength is great.

  The amount of the crosslinking aid (D) is preferably in the range of 0.1 to 3 parts by weight with respect to 100 parts by weight of the specific rubber component (A). If the blending amount of the crosslinking aid is too small, there is a tendency that it is difficult to sufficiently advance the crosslinking reaction. If the blending amount of the crosslinking aid is too large, the crosslinking density becomes too large and adhesion is caused. There is a tendency for power to decline.

<Softener>
Examples of the softener include petroleum oil softeners such as process oil, lubricating oil, paraffin, liquid paraffin, and petroleum jelly, fatty oil softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil, tall oil, And waxes such as beeswax, carnauba wax and lanolin, linoleic acid, palmitic acid, stearic acid, lauric acid and the like.

  The blending amount of the softener is usually 40 parts by weight or less with respect to 100 parts by weight of the specific rubber component (A).

  Among the softeners, softeners having a pour point of −40 ° C. or less are preferable. For example, polyalphaolefin, dioctyl phthalate (DOP), dioctyl adipate (DOA), dioctyl sebacate (DOS), dibutyl sebacate (DBS) ) Etc. These may be used alone or in combination of two or more. Of these, poly-α-olefins are preferred from the viewpoint of good compatibility with the specific rubber component (A) and difficulty in bleeding. The poly α olefin is obtained by polymerizing an α olefin having 6 to 16 carbon atoms. In the polyalphaolefin, the smaller the molecular weight, the lower the viscosity and the lower the pour point.

The lower the pour point, the harder the softener becomes harder to cure at extremely low temperatures. Therefore, the lower the pour point, the greater the effect of suppressing the crystallization of the rubber component at extremely low temperatures. The pour point of a more preferable softener is −40 ° C. or lower. On the other hand, if the pour point is too low, it tends to volatilize during operation of the fuel cell. Therefore, the pour point of the softener is desirably -80 ° C or higher.
The pour point may be measured according to JIS K2269 (1987).

《Reinforcing agent》
Examples of the reinforcing agent include carbon black and silica. The grade of the 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.

  The compounding amount of the reinforcing agent is usually in the range of 10 to 150 parts by weight with respect to 100 parts by weight of the specific 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 compounding amount of the plasticizer is usually 40 parts by weight or less with respect to 100 parts by weight of the specific rubber component (A).

  Examples of the anti-aging agent include phenols, imidazoles, and waxes. The compounding amount of the anti-aging agent is usually in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the specific rubber component (A).

<Rubber member for sealing>
The rubber member for sealing (hereinafter sometimes referred to as “seal rubber member”) is preferably a rubber that is crosslinked with an organic peroxide (crosslinking agent), and specifically, the solid exemplified above. Examples thereof include rubber (EPM, EPDM, NBR, H-NBR). Of these, EPM or EPDM having an ethylene content of 60% by weight or less, particularly preferably 53% by weight or less is preferred from the viewpoint of improving the sealing performance at extremely low temperatures.

  As the rubber composition forming the sealing rubber member, a specific cross-linking agent (B) can be used together with the solid rubber. Further, the rubber composition forming the sealing rubber member includes additives other than the adhesive component (C), for example, a crosslinking aid, a softening agent, a reinforcing agent, a plasticizer, an anti-aging agent, a tackifier, and a processing. Various additives used in ordinary rubber compositions such as auxiliaries may be blended.

<Fuel cell seal body>
The fuel cell sealing member of the present invention, a configuration for a fuel cell member, and a rubber member for sealing it, those formed by bonding through an adhesive layer, also the rubber members together to seal the components for the fuel cell but also the the like formed by bonding through an adhesive layer.

  The fuel cell components sealed by the rubber member vary depending on the type and structure of the fuel cell. For example, separators (metal separators, etc.), gas diffusion layers (GDL), MEAs (electrolyte membranes, electrodes) Etc.

  FIG. 1 mainly shows a single cell 1 in a fuel cell in which a plurality of cells are stacked. The cell 1 includes an MEA 2, a gas diffusion layer (GDL) 3, a rubber member 4a, A separator 5 and an adhesive layer 6 are provided. In addition, separators 5 facing each other in cells (not shown) adjacent to each other in the stacking direction are bonded to the rubber member 4b through an adhesive layer 6.

  As the fuel cell seal body of the present invention, for example, as shown in FIG. 1, a separator 5 and rubber members 4a and 4b are bonded through an adhesive layer 6, and MAE 2 and rubber member 4a are bonded to each other. 6, the gas diffusion layer 3 and the rubber member 4a are bonded via the adhesive layer 6, and the adjacent rubber members 4a are bonded via the adhesive layer 6 Etc.

  Although not shown, the MEA 2 includes a pair of electrodes disposed on both sides in the stacking direction with the electrolyte membrane interposed therebetween. The electrolyte membrane and the pair of electrodes have a rectangular thin plate shape. Gas diffusion layers 3 are disposed on both sides in the stacking direction with the MEA 2 interposed therebetween. The gas diffusion layer 3 is a porous layer and has a rectangular thin plate shape.

  The separator 5 is preferably made of a metal such as titanium, and a metal separator having a carbon thin film such as a DLC film (diamond-like carbon film) or a graphite film is particularly preferable from the viewpoint of conduction reliability. The separator 5 has a rectangular thin plate shape and is provided with a total of six grooves extending in the longitudinal direction. The cross section of the separator 5 has an uneven shape due to the grooves. The separators 5 are opposed to each other on both sides of the gas diffusion layer 3 in the stacking direction. A gas flow path 7 for supplying gas to the electrode is defined between the gas diffusion layer 3 and the separator 5 by using an uneven shape. Further, between the separators 5 facing each other in a cell (not shown) adjacent in the stacking direction, a refrigerant flow path 8 for flowing a refrigerant is defined using an uneven shape.

  The sealing rubber member 4a has a rectangular frame shape and is thicker in the stacking direction than the sealing rubber member 4b. The rubber member 4 a is bonded to the peripheral portion of the MEA 2 and the gas diffusion layer 3 and the separator 5 via the adhesive layer 6, and seals the peripheral portion of the MEA 2 and the gas diffusion layer 3. In FIG. 1, the rubber member 4 a uses two members that are divided into upper and lower parts, but may be a single rubber member in which both are combined.

  The sealing rubber member 4b has a rectangular frame shape and is thinner in the stacking direction than the sealing rubber member 4a. The rubber member 4b is bonded to a separator 5 facing away from a cell (not shown) adjacent in the stacking direction via an adhesive layer 6. The refrigerant flow path 8 is sealed between the separators 5 facing away by the rubber member 4b.

  During operation of a fuel cell such as a polymer electrolyte fuel cell, fuel gas and oxidant gas are supplied through the gas flow path 7 respectively. Further, the refrigerant flows through the refrigerant flow path 8 in order to relieve the heat generated during power generation. Here, the peripheral edge of the MEA 2 is sealed by a sealing rubber member 4 a via the adhesive layer 6. For this reason, gas mixing and leakage do not occur. Further, the separators 5 facing each other in cells (not shown) adjacent to each other in the stacking direction are also sealed with a rubber member 4 b for sealing via an adhesive layer 6. For this reason, it is difficult for the refrigerant to leak from the refrigerant flow path 8 to the outside.

  The fuel cell seal body of the present invention can be produced, for example, as follows. That is, for the rubber member for sealing, for example, a rubber composition containing the above EPDM, organic peroxide (crosslinking agent) and various additives as required is prepared, and this is subjected to predetermined conditions (130 to 170 ° C. × 3 to 30 minutes). The rubber member is preferably molded into a predetermined shape according to the shape of the seal portion. In this case, since complicated alignment with the constituent members for the fuel cell is not required, continuous processing is facilitated, and the productivity of the fuel cell can be further improved. In addition, as the sealing member, it is also possible to use unvulcanized rubber.

  The liquid rubber composition for the adhesive layer can be prepared, for example, as follows. That is, first, materials other than the crosslinking agent (B), the adhesive component (C), and the crosslinking aid (D) are premixed and kneaded at 80 to 140 ° C. for several minutes. Next, the obtained kneaded product is cooled, and a crosslinking agent (B), an adhesive component (C) and, if necessary, a crosslinking aid (D) are added. And using rolls, such as an open roll, it kneads for 5 to 30 minutes at roll temperature 40-70 degreeC. The adhesive component (C) may be blended in the preliminary mixing stage.

  Next, by applying the liquid rubber composition to one or both of the fuel cell constituent member such as a metal separator and the rubber member sealing the same, a fuel cell constituent member such as a metal separator; It is possible to obtain the fuel cell seal body of the present invention in which a rubber member is bonded via an adhesive layer.

  The viscosity (normal temperature) of the liquid rubber composition measured by a B-type viscometer is usually 10000 Pa · s or less, preferably 500 to 5000 Pa · s.

  Examples of the method for applying the liquid rubber composition include dispenser application and the like, and the application may usually be performed under normal temperature conditions.

  The thickness of the adhesive layer in the fuel cell seal body of the present invention is usually 0.01 to 0.5 mm, preferably 0.05 to 0.3 mm.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “parts” and “%” mean weight standards.

  First, prior to the examples and comparative examples, the following rubber composition materials were prepared.

<< Specific rubber component (A) >>
[Liquid EPDM (A1)]
Mitsui Chemicals, Mitsui PX 068 (Brookfield rotational viscosity = 10 Pa · s / normal temperature, ethylene content = 50%, diene content = 11%)
[EPDM (A2)]
Manufactured by Sumitomo Chemical Co., Ltd., Esprene 505 (Mooney viscosity = 75 [ML (1 + 4) 100 ° C.], ethylene content = 50%, diene content = 10%)
[EPDM (A3)]
JSR EP27 (Mooney viscosity = 105 [ML (1 + 4) 100 ° C.], ethylene content = 54%, diene content = 4.5%), manufactured by JSR Corporation

<< Specific cross-linking agent (B) >>
[Peroxyketal (B1)]
1,1-di (t-butylperoxy) cyclohexane (manufactured by NOF Corporation, perhexa C-40, purity 40%, half hour temperature for 1 hour = 111.1 ° C.)
[Dialkyl peroxide (B2)]
(Manufactured by NOF CORPORATION, perhexine 25B-40, purity 40%, 1 hour half-life temperature = 149.9 ° C.)

<< Adhesive component (C) >>
[Resorcinol compound (C1)]
Tachiroll 620, manufactured by Taoka Chemical Industries
[Melamine compound (C2)]
SUMIKANOL 507AP, manufactured by Sumitomo Chemical Co., Ltd.
[Silane coupling agent (C3)]
3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403)

<< Crosslinking aid (D) >>
[Maleimide compound (D1)]
Made by Ouchi Emerging Chemical Industries, Balnock PM

<Softener (E)>
[Paraffinic process oil (E1)]
Idemitsu Kosan Co., Ltd., Diana Process Oil PW380 (pour point = -15 ° C)

<< Reinforcing agent (F) >>
[Carbon black (GPF class) (F1)]
Cabot Japan, Show Black IP200
[Silica (F2)]
Carplex 1120 manufactured by Degussa

"solvent"
Tetrahydrofuran (THF)

[Example 1]
(Preparation of liquid rubber composition for adhesive layer)
The components shown in Table 1 below were blended in the proportions shown in the same table to prepare a liquid rubber composition. That is, first, in Table 1, the rubber component (A), the softener (E), and the reinforcing agent (F) were kneaded at 120 ° C. for 5 minutes using a Banbury mixer. After cooling the kneaded product, a cross-linking agent (B), an adhesive component (C) and a cross-linking auxiliary agent (D) are added and kneaded at 50 ° C. for 10 minutes using an open roll to obtain a liquid rubber composition (Type B Viscosity with a viscometer: 3000 Pa · s / normal temperature) was prepared.

(Preparation of vulcanized rubber for sealing)
EPDM (Sumitomo Chemical Co., Esprene 505) 100 parts, paraffinic process oil (Idemitsu Kosan Co., Diana Process Oil PW380) 10 parts, GPF grade carbon black (Cabot Japan Co., Show Black IP200) 35 parts, silica ( 10 parts of Carplex 1120) manufactured by Degussa Co. were kneaded at 120 ° C. for 5 minutes using a Banbury mixer. After cooling the kneaded product, 5 parts of peroxyketal [1,1-di (t-butylperoxy) cyclohexane (manufactured by NOF Corporation, Perhexa C-40) is added, and an open roll is used at 50 ° C. The rubber composition was prepared by kneading for 10 minutes. The rubber composition was crosslinked at 150 ° C. for 10 minutes, and then a rubber piece was cut out to produce a vulcanized rubber for sealing (thickness 5 mm, size 25 mm × 60 mm).

  Using the liquid rubber composition and vulcanized rubber obtained as described above, each characteristic was evaluated according to the following criteria. The results are also shown in Table 1 above.

[Vulcanized rubber adhesion (vulcanized rubber / adhesive layer)]
A 90 ° peel test in accordance with JIS K6256-2 (2006) was conducted to evaluate adhesion. That is, the liquid rubber composition prepared above was applied to one side of the vulcanized rubber produced above (thickness 5 mm, size 25 mm × 60 mm) using a JETMERTER 2 manufactured by Musashi Engineering Co., Ltd. (condition: injection speed) 60 mm / sec, injection pressure 0.05 to 0.06 MPa), and this was held at 150 ° C. for 30 minutes to crosslink and bond to prepare a test piece (adhesive layer thickness 0.1 mm). Next, the test piece was attached to a predetermined test jig, a 90 ° peel test was performed, and the adhesion was evaluated. The evaluation criteria were “◯” when the rubber was broken, and “X” when the interface was peeled off.

[Metal adhesion (vulcanized rubber / adhesion layer / metal)]
A 90 ° peel test based on JIS K6256-2 (2006) was performed to evaluate the adhesion. That is, the liquid rubber composition prepared above was applied to the surface of a titanium plate (thickness 5 mm, size 25 mm × 60 mm) using a JETMERTER 2 manufactured by Musashi Engineering Co., Ltd. (conditions: injection speed 60 mm / sec, injection Pressure 0.05-0.06 MPa). Next, the vulcanized rubber produced above (thickness 5 mm, size 25 mm × 60 mm) was placed on the surface. And while pressing from the vulcanized rubber side, it hold | maintained at 150 degreeC for 30 minute (s), and the test piece (thickness of an adhesive layer 0.1mm) was produced by making it bridge | crosslink and adhere | attach. Next, the test piece was attached to a predetermined test jig, a 90 ° peel test was performed, and the adhesion was evaluated. The evaluation criteria were “◯” when the rubber was broken, and “X” when the interface was peeled off.

[Electrolytic membrane adhesion (vulcanized rubber / adhesive layer / electrolyte membrane)]
In the evaluation of the metal adhesion, the same procedure as described above was used except that an electrolyte membrane (thickness 0.001 mm, size 10 mm × 50 mm) made of a fluororesin (manufactured by DuPont, Nafion) was used instead of the titanium plate. The adhesiveness was evaluated. The evaluation criteria were “◯” when the rubber was broken, and “X” when the interface was peeled off.

[Examples 2-5, 7]
Except for using each rubber composition shown in Table 1 above as the liquid rubber composition for the adhesive layer, vulcanized rubber adhesion, metal adhesion, and electrolyte membrane adhesion were evaluated according to Example 1. It was. The results are also shown in Table 1 above. Incidentally, the manufacturing conditions (vulcanization conditions) of the specimen using the rubber composition of Example 7, was set to 190 ° C. × 30 minutes.

[Comparative Example 1]
Example 1 except that instead of the liquid rubber composition, the solvent-based rubber composition shown in Table 1 above (viscosity by B-type viscometer: 2800 Pa · s / room temperature) was used as the rubber composition for the adhesive layer. The vulcanized rubber adhesion, metal adhesion, and electrolyte membrane adhesion were evaluated according to the above. The results are also shown in Table 1 above.

[Examples 6 and 8]
Metal adhesion and electrolyte membrane adhesion were evaluated according to Example 1 except that unvulcanized rubber was used instead of vulcanized rubber for sealing. Incidentally, the manufacturing conditions (vulcanization conditions) of the specimen using the rubber composition of Example 8, was set to 190 ° C. × 30 minutes.

(Preparation of unvulcanized rubber)
A rubber composition similar to that used for producing the vulcanized rubber of Example 1 for sealing was prepared. And from this rubber composition, an unvulcanized rubber piece was cut out to produce an unvulcanized rubber for sealing (thickness 5 mm, size 25 mm × 60 mm).

[Metal adhesion (unvulcanized rubber / adhesion layer / metal)]
A 90 ° peel test based on JIS K6256-2 (2006) was performed to evaluate the adhesion. That is, the liquid rubber composition prepared above was applied to the surface of a titanium plate (thickness 5 mm, size 25 mm × 60 mm) using a JETMERTER 2 manufactured by Musashi Engineering Co., Ltd. (conditions: injection speed 60 mm / sec, injection Pressure 0.05-0.06 MPa). Next, the unvulcanized rubber (thickness 5 mm, size 25 mm × 60 mm) prepared above was placed on the surface. Subsequently, a test piece (adhesive layer thickness 0.1 mm) was prepared by holding and crosslinking and bonding at 150 ° C. for 30 minutes while pressing from the unvulcanized rubber side. Next, the test piece was attached to a predetermined test jig, a 90 ° peel test was performed, and the adhesion was evaluated. The evaluation criteria were “◯” when the rubber was broken, and “X” when the interface was peeled off.

[Electrolytic membrane adhesion (unvulcanized rubber / adhesive layer / electrolyte membrane)]
In the evaluation of the metal adhesion, the same procedure as described above was used except that an electrolyte membrane (thickness 0.001 mm, size 10 mm × 50 mm) made of a fluororesin (manufactured by DuPont, Nafion) was used instead of the titanium plate. The adhesiveness was evaluated. The evaluation criteria were “◯” when the rubber was broken, and “X” when the interface was peeled off.

  From the results of Table 1 above, the products of all the examples have the rubber component (vulcanized rubber, unvulcanized rubber), metal, because the adhesive component (C) is blended in the liquid rubber composition for the adhesive layer. Or it was excellent in adhesiveness with an electrolyte membrane. In addition, since all the products of the examples do not contain the adhesive component (C) in the rubber member for sealing (vulcanized rubber, unvulcanized rubber), there is no mold contamination, low cost and excellent mass productivity. Yes. Incidentally, among the examples, the products of Examples 1 to 6 [use of peroxyketal (B1) as a cross-linking agent] compared to the products of Examples 7 and 8 [use of dialkyl peroxide (B2) as a cross-linking agent]. It is preferable to vulcanize at a lower temperature.

  In addition, when using liquid EPM, liquid NBR, and liquid H-NBR instead of liquid EPDM (A1) in the liquid rubber composition for the adhesive layer, the same evaluation results as when using the above liquid EPDM are obtained. Obtained.

  On the other hand, since the product of Comparative Example 1 does not contain the adhesive component (C) in the solvent-based rubber composition for the adhesive layer, the rubber member (vulcanized rubber, unvulcanized rubber), metal or electrification Adhesion with the membrane was inferior.

  The liquid rubber composition of the present invention is a fuel cell sealing body in which a constituent member for a fuel cell such as a metal separator and a rubber member for sealing it are bonded via an adhesive layer, or the rubber members are bonded to each other. It is used for the adhesive layer of the fuel cell seal body that is bonded via Since the adhesive layer is formed of a liquid rubber composition containing (A) to (C), the adhesive reliability is high. Therefore, it is not necessary to knead the adhesive component (C) into the rubber member. Therefore, there is no problem of mold contamination, and it is excellent in mass productivity at low cost.

1 cell 2 MEA
3 Gas diffusion layer 4a, 4b Rubber member 5 Separator 6 Adhesive layer

Claims (9)

A sealing rubber member in which a metal separator is bonded through an adhesive layer; and a sealing rubber member in which a membrane electrode assembly is bonded through an adhesive layer, and is bonded to the membrane electrode assembly. A fuel cell seal body in which rubber members are bonded to each other through an adhesive layer , and all of the adhesive layers have a thickness of 0.01 to 0.5 mm, and the following (A) to (C): A fuel cell sealing body, which is a layer formed by crosslinking a liquid non-solvent rubber composition.
(A) A rubber component containing at least one solid rubber selected from the group consisting of ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber and hydrogenated acrylonitrile-butadiene rubber together with liquid rubber.
(B) A crosslinking agent comprising an organic peroxide.
(C) At least one adhesive component selected from the group consisting of a resorcinol compound, a melamine compound, an aluminate coupling agent, and a silane coupling agent. The fuel cell seal body according to claim 1, wherein the liquid non-solvent rubber composition has a viscosity of 500 to 10,000 Pa · s.   The fuel cell seal body according to claim 1 or 2, wherein the content of the liquid rubber is 40% by weight or more of the total amount of (A).   The liquid rubber is at least one selected from the group consisting of liquid ethylene-propylene rubber, liquid ethylene-propylene-diene rubber, liquid acrylonitrile-butadiene rubber and liquid hydrogenated acrylonitrile-butadiene rubber. The fuel cell seal body according to one item.   The fuel cell sealing body according to any one of claims 1 to 3, wherein the liquid rubber is at least one of a liquid ethylene-propylene rubber and a liquid ethylene-propylene-diene rubber having an ethylene content of 60% by weight or less.   The fuel cell seal body according to any one of claims 1 to 5, wherein the organic peroxide is an organic peroxide having a one-hour half-life temperature of 160 ° C or lower. The fuel cell seal body according to any one of claims 1 to 6, wherein the liquid non-solvent rubber composition further contains the following (D).
(D) A crosslinking aid.   The fuel cell seal body according to any one of claims 1 to 7, wherein the rubber member for sealing is vulcanized rubber.   The fuel cell seal body according to any one of claims 1 to 8, wherein the rubber member for sealing contains at least one of ethylene-propylene rubber and ethylene-propylene-diene rubber having an ethylene content of 60% by weight or less.

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