JP6681246B2 - Method of manufacturing seal member for fuel cell - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a fuel cell seal member used for sealing a fuel cell constituent member and a method for manufacturing the same.

  A fuel cell generates electricity by an electrochemical reaction of gas, has high power generation efficiency, emits clean gas, and has very little influence on the environment. Among them, the polymer electrolyte fuel cell can be operated at a relatively low temperature and has a large power density. Therefore, various applications such as power generation and power supply for automobiles are expected.

  In the polymer electrolyte fuel cell, a cell in which a membrane electrode assembly (MEA) or the like is sandwiched between separators serves as a power generation unit. The MEA includes a polymer membrane (electrolyte membrane) serving as an electrolyte, a pair of electrode catalyst layers (fuel electrode (anode) catalyst layer, oxygen electrode (cathode) catalyst layer) arranged on both sides in the thickness direction of the electrolyte membrane, Consists of. A porous layer for further diffusing gas is arranged on the surfaces of the pair of electrode catalyst layers. Fuel gas such as hydrogen is supplied to the fuel electrode side, and 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. A polymer electrolyte fuel cell is constructed by tightening cell stacks in which a large number of the above cells are stacked by end plates and the like arranged at both ends in the cell stacking direction.

  The separator is provided with a flow path of gas supplied to each electrode and a flow path of a refrigerant for alleviating heat generation during power generation. For example, when the gas supplied to each electrode mixes, there arises a problem such as a decrease in power generation efficiency. Further, the electrolyte membrane has proton conductivity in the state of containing water. Therefore, it is necessary to keep the electrolyte membrane in a wet state during operation. Therefore, in order to prevent gas mixture, gas and refrigerant leakage, and to keep the inside of the cell in a wet state, it is important to secure the sealability around the MEA and the porous layer and between the adjacent separators. Becomes As a seal member for sealing these constituent members, for example, a seal member (rubber gasket) made of ethylene-propylene-diene terpolymer rubber (EPDM), ethylene-propylene copolymer rubber (EPM), etc. has been proposed. (See Patent Documents 1 and 2).

JP, 2009-94056, A JP, 2010-146781, A

  As the rubber component of the fuel cell sealing member, from the viewpoint of satisfactorily obtaining the mechanical properties (tensile strength, breaking elongation, hardness, etc.) and settling resistance (sealing property) required for the fuel cell sealing member, Usually, solid rubber (millable rubber) such as EPDM or EPM is used, and an organic peroxide is used as a crosslinking agent thereof.

  By the way, in recent years, in the process of manufacturing a seal member for a fuel cell, in order to improve the productivity, it is required to improve the injection property during injection molding. That is, since the fuel cell seal member is usually a frame-shaped seal member having a thickness of about 1 mm × a size of 10 cm square or more and a frame width of 3 to 4 mm, it is difficult to form by injection molding (by injection molding). Since it was difficult to spread the rubber to every corner of the mold), the improvement is desired.

  As a method of improving the above-mentioned injection property, for example, there is a method of blending a softening agent (plasticizer) into a rubber composition for forming a seal member for a fuel cell to reduce the viscosity of the rubber composition.

  However, when a rubber composition containing a millable rubber such as EPDM or EPM as a polymer is blended with a softening agent to lower the viscosity so that the injection property is improved and the sealing member for a fuel cell is injection-molded, Since the mechanical properties and the settling resistance required for the sealing member for automobiles cannot be obtained, the improvement is required.

  The present invention has been made in view of the above circumstances, and provides a fuel cell seal member having excellent injection moldability while maintaining the mechanical properties and settling resistance required for the seal member, and a method for manufacturing the same. , And its purpose.

In order to achieve the above-mentioned object, the present invention is a method for producing a sealing member for a fuel cell shown in (α) below, which contains the following components (A) to (D), and (A) The content ratio of the component to the component (B) is in the range of A / B = 95/5 to 40/60 in terms of weight ratio, and (A) and (B) are added to 100 parts by weight of the total amount of the components ( A step of kneading the rubber composition in which the content of the component C) is 0.4 to 12 parts by weight and the content of the component (D) is 5 to 40 parts by weight; and the injection of the kneaded rubber composition. The gist is a method for manufacturing a fuel cell seal member including a step of performing molding.
(Α) A fuel cell seal member used for sealing a component member of a fuel cell, comprising the following components (A) to ( D ) and containing (A) component and (B) component: content ratio, by weight, ranging der of a / B = 95 / 5~40 / 60 is, relative to 100 parts by weight of the total of components (a) and (B), the content of the component (C) 0.4 to 12 parts by weight and, (D) component for a fuel cell sealing member comprising a crosslinked product of the rubber composition content of 5 to 40 parts by weight of.
(A) d styrene - propylene - Jiengo nothing Ranaru solid rubber.
(B) a liquid form ethylene - propylene - Jiengo nothing Ranaru liquid rubber.
(C) A crosslinking agent composed of an organic peroxide.
(D) At least one of paraffin oil and poly-α-olefin compound.

  That is, the present inventors have conducted extensive research to solve the above-mentioned problems. In the process of the research, ethylene-propylene rubber and ethylene-propylene-diene rubber, which have excellent properties as rubber components of the fuel cell sealing member, were used, and the organic peroxide was used so as not to hinder the power generation of the fuel cell. The use of oxides as the crosslinking agent was investigated. Further, it was investigated to use liquid rubber as the rubber component so that the material has excellent injectability during injection molding without blending a softening agent in the material. However, the desired mechanical properties could not be obtained only with the liquid rubber. Further, even if the liquid rubber is mixed with the solid rubber, if the liquid rubber is too much, it cannot be uniformly kneaded, and further, the rubber is stuck to the kneading machine, which is a problem of poor workability. , Further researched. As a result, when a solid rubber (A) of ethylene-propylene rubber or ethylene-propylene-diene rubber and a liquid rubber (B) of liquid ethylene-propylene rubber or liquid ethylene-propylene-diene rubber were contained at a specific ratio. The inventors have found that the injection-moldability is excellent while maintaining the mechanical properties and settling resistance required for the seal member for fuel cells, and arrived at the present invention.

  The fuel cell seal member of the present invention is a solid rubber (A) made of at least one of ethylene-propylene rubber and ethylene-propylene-diene rubber, and a liquid made of at least one of liquid ethylene-propylene rubber and liquid ethylene-propylene-diene rubber. A rubber (B) and a crosslinking agent (C) composed of an organic peroxide are contained, and the content ratio of the component (A) and the component (B) is A / B = 95/5 in weight ratio. It consists of a cross-linked product of a rubber composition in the range of 40/60. From this, the fuel cell seal member of the present invention can be injection-molded (the rubber can be spread to every corner of the mold by injection molding while maintaining the mechanical properties and settling resistance required for the seal member). It is also excellent.

  In particular, when the liquid rubber (B) is a liquid ethylene-propylene-diene rubber having a diene content of 4% by weight or more, the settling resistance becomes excellent.

  Further, when the fuel cell sealing member is made of a crosslinked body of a rubber composition containing at least one (D) of paraffin oil and a poly-α-olefin compound together with the above-mentioned components (A) to (C), bleed-out is further suppressed. Come to do.

  Further, the method for producing a seal member for a fuel cell of the present invention contains the above components (A) to (C), and the content ratio of the component (A) and the component (B) is A / It is provided with a step of kneading a rubber composition having a range of B = 95/5 to 40/60, and a step of performing injection molding of the kneaded rubber composition. From this, it is possible to favorably manufacture a fuel cell seal member having excellent injection properties during injection molding and having the above-described excellent mechanical properties and settling resistance.

It is sectional drawing which shows an example of the fuel cell sealing body of this invention. It is sectional drawing which shows an example using the sealing member for fuel cells 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 fuel cell seal member of the present invention (hereinafter, may be simply referred to as “seal member”) is used for sealing a component member of a fuel cell, and as described above, A rubber composition containing the components (A) to (C), and the content ratio of the component (A) to the component (B) is A / B = 95/5 to 40/60 in weight ratio. It consists of a cross-linked body.
(A) Solid rubber comprising at least one of ethylene-propylene rubber and ethylene-propylene-diene rubber.
(B) A liquid rubber comprising at least one of liquid ethylene-propylene rubber and liquid ethylene-propylene-diene rubber.
(C) A crosslinking agent composed of an organic peroxide.

The rubber components (A) and (B) are the main components of the rubber composition, and usually account for the majority of the entire rubber composition. Then, as described above, a solid rubber (A) composed of at least one of ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber (EPDM), liquid ethylene-propylene rubber (liquid EPM) and liquid ethylene-propylene- A liquid rubber (B) made of at least one of diene rubber (liquid EPDM) is contained at a weight ratio of A / B = 95/5 to 40/60, preferably A / B = 90/10. It is contained at a ratio of 50/50, and more preferably at a ratio of A / B = 85/15 to 65/35. Here, the “solid rubber” is a rubber that is solid at room temperature (23 ° C.) and has a Mooney viscosity (ML _{1 + 4} 100 ° C.) of 5 or more at 100 ° C. according to JIS K6300-1. Says rubber. The "liquid rubber" refers to a rubber having a viscosity of 1000 Pa · s or less at room temperature (23 ° C) measured by a B-type viscometer according to JIS Z8803. Further, when the solid rubber content is higher (the liquid rubber content is lower) than the weight ratio of the rubber components (A) and (B), good injection moldability cannot be obtained, and the solid rubber content is lower than the weight ratio ( If the amount of liquid rubber is large), the desired tensile strength cannot be obtained, and problems such as poor processability during kneading tend to occur.

  The ethylene content in the rubber components (A) and (B) is preferably 60% by weight or less, and particularly preferably 53% by weight or less, from the viewpoint of improving the sealing property at extremely low temperatures. On the other hand, if the ethylene content is too low, the rubber physical properties deteriorate, and it becomes difficult to secure the elongation and tensile properties required for the sealing member. Therefore, the ethylene content is 40% by weight or more. Is preferred.

  From the viewpoint of acid resistance and water resistance in the operating environment of the fuel cell, EPDM is preferably used as the component (A). In particular, when the amount of the diene in the EPDM increases, the crosslink density of the seal member, which is a crosslinked body, increases in proportion thereto, and the low temperature sealing property is further improved. For this reason, the amount of diene (mass ratio of diene component) in the EPDM is preferably in the range of 1 to 20% by weight, more preferably 3 to 15% by weight.

  Also, as the component (B), liquid EPDM is preferably used from the same viewpoint as the component (A). It is preferable that the liquid EPDM is a liquid EPDM having a diene content of 4% by weight or more, because it is more excellent in resistance to settling, and from the same viewpoint, a liquid EPDM having a diene content of 5% by weight or more is particularly preferable. Liquid EPDM having a diene content of 6% by weight or more is preferred. The upper limit of the diene content is 12% by weight.

  As the diene component of the EPDM of the component (A) and the liquid EPDM of the component (B), 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, 2-methallyl-5-norbornene, 2-isopropenyl-5-norbornene and the like can be mentioned.

  The cross-linking agent (C) of the rubber components (A) and (B) is composed of an organic peroxide. Examples of the organic peroxide include peroxyketal, peroxyester, diacyl peroxide, peroxydicarbonate, dialkyl peroxide, hydroperoxide and the like. These may be used alone or in combination of two or more. Among such organic peroxides, for example, an organic peroxide having a one-hour half-life temperature of 160 ° C. or lower is preferably used, and the one-hour half-life temperature is required for adhesion to the electrolyte membrane. It is preferable to use an organic peroxide having a temperature of 130 ° C. or lower. In addition, peroxyketals and peroxyesters having a one-hour half-life temperature of 100 ° C. or higher are easily crosslinked at a temperature of about 130 ° C., and the rubber composition kneaded with a crosslinking agent is excellent in handleability. Of these, at least one is preferable, and one having 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 the organic peroxide having a one-hour half-life temperature of 160 ° C. or less in the cross-linking agent (C) means that the concentration of the organic peroxide (active oxygen amount) is the initial value. It is time to halve. Therefore, the “half-life temperature” is an index showing the decomposition temperature of the organic peroxide. The "1 hour half-life temperature" is the temperature at which the half-life is 1 hour. That is, the lower the one-hour half-life temperature, the easier the decomposition at low temperature. For example, by using an organic peroxide having a 1-hour half-life temperature of 160 ° C. or less, crosslinking can be performed at a lower temperature (specifically, 150 ° C. or less) in a short time. Therefore, for example, the fuel cell sealing body of the present invention can be used even in the vicinity of the electrolyte membrane of the polymer electrolyte fuel cell.

  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-hexyl) Examples include peroxy) -3,3,5-trimethylcyclohexane and 1,1-di (t-butylperoxy) -2-methylcyclohexane.

  Examples of the peroxyester include t-butylperoxybenzoate, t-butylperoxyacetate, t-hexylperoxybenzoate, 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 Acid, t-hexyl peroxy isopropyl monocarbonate is mentioned.

  Of these, 1,1-di (t-butylperoxy) cyclohexane, t-butylperoxyacetate, and t-butyl are used because the reaction with the rubber components (A) and (B) is relatively fast. Peroxyisopropyl monocarbonate is preferred. Especially, when t-butyl peroxy isopropyl monocarbonate is used, crosslinking can be performed in a shorter time.

  The amount of the specific cross-linking agent (C) (in the case of a raw material having a purity of 100%) is 0.4 to 12 parts by weight based on 100 parts by weight of the total amount of the rubber components (A) and (B). Is preferred. If the blending amount of the specific crosslinking agent (C) is too small, it tends to be difficult to sufficiently proceed the crosslinking reaction, and if the blending amount of the specific crosslinking agent (C) is too large, the crosslinking becomes There is a tendency that the crosslink density increases during the reaction and the elongation decreases.

  In addition to the components (A) to (C), at least one of paraffin oil and poly-α-olefin compound (D), fatty acid potassium, fatty acid sodium, and the like are contained in the rubber composition used in the seal member of the present invention. Various additives such as a fatty acid salt, a softening agent (plasticizer), a crosslinking aid, a reinforcing agent, an antiaging agent, a tackifier, and a processing aid may be blended.

As described above, it is preferable to blend at least one of the paraffin oil and the poly-α-olefin compound (D) because bleed-out can be further suppressed. The kinematic viscosity at 100 ° C. of the poly α-olefin compound (PAO), from the viewpoint of low-temperature resistance, more preferably not more than ^{8 mm} 2 / s, more preferably in the range of 2 to 8 mm ² / s . The kinematic viscosity of the poly-α-olefin compound is measured according to JIS K 2283.

  The blending amount of the component (D) is preferably 5 to 40 parts by weight based on 100 parts by weight of the total amount of the rubber components (A) and (B) from the viewpoint of suppressing bleeding out. .

  When the fatty acid salt such as fatty acid potassium or sodium fatty acid is blended, the mold releasability can be enhanced. The number of carbon atoms of the above fatty acid potassium and sodium fatty acid is not particularly limited, but it is preferable that the number of carbon atoms is in the range of 8 to 22 from the viewpoint of mold releasability, and from the same viewpoint, the number of carbon atoms is 12 to 12. The range of 18 is more preferable. From the viewpoint of mold releasability, the “fatty acid” in the above fatty acid potassium and sodium fatty acid may be saturated fatty acid or unsaturated fatty acid.

  Further, as the fatty acid potassium, specifically, potassium caprylate (saturated fatty acid salt of C8), potassium caprate (saturated fatty acid salt of C10), potassium laurate (saturated fatty acid salt of C12), potassium myristate ( C14 saturated fatty acid salt), potassium palmitate (C16 saturated fatty acid salt), potassium stearate (C18 saturated fatty acid salt), potassium oleate (C18 unsaturated fatty acid salt), potassium behenate (C22 saturated fatty acid salt) ) And the like are used alone or in combination of two or more. Specific examples of the fatty acid sodium include sodium caprylate (saturated fatty acid salt of C8), sodium caprate (saturated fatty acid salt of C10), sodium laurate (saturated fatty acid salt of C12), sodium myristate ( C14 saturated fatty acid salt), sodium palmitate (C16 saturated fatty acid salt), sodium stearate (C18 saturated fatty acid salt), sodium oleate (C18 unsaturated fatty acid salt), sodium behenate (C22 saturated fatty acid salt) ) And the like are used alone or in combination of two or more. In addition, the above-mentioned "C **" shows a carbon number.

  The amount of the fatty acid salt blended is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the total amount of the rubber components (A) and (B). The range is parts by weight. That is, when it is in such a range, the mold releasing property is more effective while maintaining the mechanical properties and the settling resistance required for the seal member.

  Examples of the softening agent include process oils, lubricating oils, petroleum softening agents such as petrolatum, castor oil, linseed oil, rapeseed oil, coconut oil and other fatty oil softening agents, tall oil, sub, beeswax, carnauba wax. , Waxes such as lanolin, linoleic acid, palmitic acid, stearic acid, and lauric acid.

  The compounding amount of the softening agent is usually in the range of 5 to 40 parts by weight with respect to 100 parts by weight of the total amount of the rubber components (A) and (B).

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

  The amount of the above-mentioned crosslinking aid compounded is preferably in the range of 0.1 to 3 parts by weight based on 100 parts by weight of the total amount of the rubber components (A) and (B). If the blending amount of the crosslinking aid is too small, it tends to be difficult to sufficiently proceed the crosslinking reaction, and if the blending amount of the crosslinking aid is too large, the crosslinking density becomes too large, and the adhesion Power tends to decrease.

  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 amount of the reinforcing agent compounded is usually in the range of 10 to 150 parts by weight based on 100 parts by weight of the total amount of the rubber components (A) and (B).

  Examples of the antiaging agent include phenol type, imidazole type and wax. The compounding amount of the antioxidant is usually in the range of 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the rubber components (A) and (B).

<Preparation of fuel cell seal member>
The fuel cell seal member of the present invention, for example, includes a rubber composition containing the components (A) to (C) and a weight ratio of the components (A) and (B) within a specific range. (The rubber composition may be blended with other various additives as necessary), and then the kneaded rubber composition is injection-molded to prepare the rubber composition. That is, the weight ratio of the components (A) and (B) is in a specific range (A / B = 95/5 to 40/60, preferably A / B = 90/10 to 50/50, and more preferably A / B). Since B = 85/15 to 65/35), it is easy to knead, and it is possible to perform mixing without sticking or unevenness. Etc. can be obtained. Moreover, since the kneaded rubber composition also has excellent injection properties, the rubber can be spread to every corner of the mold by injection molding, and as a result, productivity can be improved. A roll, a kneader, a Banbury mixer or the like is used for the above kneading. Further, the Mooney viscosity (ML _{1 + 4} 100 ° C.) at 100 ° C. of the rubber composition at the time of injection molding is preferably in the range of 5 to 30 from the viewpoint of injection moldability.

  The seal member obtained as described above can be attached to various constituent members of a fuel cell with an adhesive for use. The seal member of the present invention may be used in such a manner that the seal member is arranged without being bonded between various constituent members of the fuel cell. Further, the seal member of the present invention may be formed by injection-molding the seal member of the present invention onto the coated surface of the adhesive, in addition to sticking (post-adhering) the injection-molded product as described above. It is also possible to vulcanize and bond, and as will be described later, the constituent members such as the MEA of the fuel cell and the separator and the sealing member of the present invention are integrally molded in a mold.

<Fuel cell seal>
Examples of the fuel cell seal body of the present invention include those in which a fuel cell constituent member and a seal member that seals the member (fuel cell seal member of the present invention) are adhered via an adhesive layer. .

  The fuel cell constituent member sealed by the seal member of the present invention varies depending on the type, structure, and the like of the fuel cell. For example, a separator (metal separator or the like), a gas diffusion layer (GDL), an MEA (electrolyte membrane, Electrodes) and the like.

  An example of the fuel cell seal of the present invention is shown in FIG. FIG. 1 mainly shows a single cell 1 in a fuel cell in which a plurality of cells are stacked, and the cell 1 includes an MEA 2, a gas diffusion layer (GDL) 3, a sealing member 4a, The separator 5 and the adhesive layer 6 are provided.

  As the fuel cell seal body of the present invention, for example, as shown in FIG. 1, a separator 5 and a seal member 4a are bonded together via an adhesive layer 6, and an MEA 2 and a seal member 4a are bonded together. And those in which the gas diffusion layer 3 and the seal member 4a are adhered via the adhesive layer 6, those in which the adjacent seal members 4a are adhered via the adhesive layer 6, and the like. can give.

  Although not shown, the MEA 2 is composed of a pair of electrodes arranged 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 arranged on both sides of the MEA 2 in the stacking direction. 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 from the viewpoint of conduction reliability, a metal separator having a carbon thin film such as a DLC film (diamond-like carbon film) or a graphite film is particularly preferable. The separator 5 has a rectangular thin plate shape, and a total of six grooves extending in the longitudinal direction are recessed, and the cross section of the separator 5 has an uneven shape due to the grooves. The separators 5 are arranged facing 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 electrodes is defined between the gas diffusion layer 3 and the separator 5 by utilizing the uneven shape.

  The seal member 4a has a rectangular frame shape. The sealing member 4a is adhered to the peripheral portions of the MEA 2 and the gas diffusion layer 3 and the separator 5 via the adhesive layer 6 to seal the peripheral portions of the MEA 2 and the gas diffusion layer 3. In addition, in FIG. 1, the seal member 4a uses two members that are vertically separated, but a single seal member that is a combination of both members may be used.

  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. Here, the peripheral edge portion of the MEA 2 is sealed by the seal member 4a via the adhesive layer 6. Therefore, gas mixing and leakage do not occur.

  The fuel cell seal body of the present invention can be manufactured, for example, as follows. First, as described above, the fuel cell sealing member of the present invention is manufactured.

  Next, by applying the adhesive layer forming material (adhesive) to one or both of the fuel cell constituent member such as the metal separator and the sealing member for sealing the fuel cell constituent member such as the metal separator, It is possible to obtain the fuel cell seal body of the present invention in which the constituent member and the seal member are adhered to each other via the adhesive layer.

  As the adhesive layer forming material (adhesive), for example, a rubber paste, a rubber composition which is liquid at room temperature (23 ° C.), a primer or the like is used. Examples of the liquid rubber composition include a rubber composition containing a rubber component, an organic peroxide (crosslinking agent) and the like. Examples of the rubber component include liquid rubbers, specifically, liquid EPM, liquid EPDM, liquid acrylonitrile-butadiene rubber (liquid NBR), liquid hydrogenated acrylonitrile-butadiene rubber (liquid H-NBR). Etc. are used alone or in combination of two or more. Examples of the primer include a primer containing a copolymerization oligomer of an amino group-containing silane coupling agent and a vinyl group-containing silane coupling agent.

  Examples of the method for applying the adhesive layer-forming material include dispenser application and the like, and application may normally be performed at room temperature.

  When the liquid rubber composition is used, 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. Moreover, when using the said primer, it is 10-500 nm normally, Preferably it is 30-200 nm.

  Further, if the fuel cell constituent member and the seal member are integrated by vulcanization adhesion of the seal member to manufacture the fuel cell seal body, it can be manufactured as follows. That is, the fuel cell constituent member on which the adhesive layer is formed is arranged in the mold for molding the seal member, and the rubber composition for forming the seal member is brought into contact with the fuel cell constituent member in the mold. It is a manufacturing method such as cross-linking molding in an open state.

  Further, another example of use of the fuel cell seal member of the present invention is shown in FIG. FIG. 2 shows a rectangular thin plate shape with a rectangular shape via an adhesive layer 6 on the peripheral portion of the separator 5 having the above-mentioned uneven cross-sectional shape in which a total of six grooves extending in the longitudinal direction are recessed. It is a member provided with a lip 4b having a convex cross section. The fuel cell seal member of the present invention is used as the lip 4b. The same materials as those described above are used as the material for forming the separator 5 and the material for forming the adhesive layer 6.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.

  First, prior to Examples and Comparative Examples, materials of the rubber composition shown below were prepared.

[EPDM (A component)]
Ethylene-propylene-diene rubber (JSR, EP342)

[Liquid EPDM-1 (B component)]
Liquid EPDM (PX062 manufactured by Mitsui Chemicals, Inc.) having an ethylene content of 50% by weight, a diene content of 4.7% by weight, and a number average molecular weight of 3160.

[Liquid EPDM-2 (B component)]
Liquid EPDM having an ethylene content of 52% by weight, a diene content of 6.9% by weight, and a number average molecular weight of 3850 (1481010A manufactured by Mitsui Chemicals, Inc.)

〔Carbon black〕
Tokai Carbon Co., Seast 116

[Paraffin oil (D component)]
Japan Sun Oil Company, Sunper 110

[PAO (D component)]
Poly-α-olefin compound having a kinematic viscosity at 100 ° C. of 8 mm ² / s (Chevron Phillips, Synfluid PAO 8cSt)

[Peroxide (C component)]
NOF CORPORATION Perhexa C-40

[Examples 1 to 11, Comparative Examples 1 to 5]
A rubber composition was prepared by mixing the components shown in Tables 1 and 2 described below in the proportions shown in the table and kneading the mixture using a Banbury mixer and an open roll.
Further, the above rubber composition was vulcanized by holding at 160 ° C. for 10 minutes to produce a vulcanized rubber having a predetermined thickness.

  The properties of the rubber composition and the vulcanized rubber obtained as described above were evaluated according to the following criteria. The results are also shown in Tables 1 and 2 below.

<Workability>
When kneading the rubber composition with an open roll, those that could be kneaded without problems were evaluated as ◯, and those that could not be kneaded were evaluated as x.

<Moonie viscosity>
The Mooney viscosity (ML _{1 + 4} 100 ° C.) of the rubber composition (after kneading with an open roll) at 100 ° C. was measured according to JIS K 6300-1.
In addition, Tables 1 and 2 described below show the Mooney viscosity index of each rubber composition when the Mooney viscosity of the rubber composition of Comparative Example 1 is used as a reference (100).
That is, the Mooney viscosity index was calculated by the following formula.
Mooney viscosity index = (Moonie viscosity of each rubber composition (ML _{1 + 4} 100 ° C.)) / (Standard Mooney viscosity of rubber composition of Comparative Example 1 (ML _{1 + 4} 100 ° C.)) × 100
In Tables 1 and 2 described later, when the Mooney viscosity index is 90 or less, it is evaluated as ◯ because the injection property during injection molding is improved, and when the Mooney viscosity index exceeds 90, the injection molding is performed. It was evaluated as x because of poor ejection property.

<Hardness>
The hardness (type A) of the vulcanized rubber was measured according to JIS K 6253-3.
It should be noted that Tables 1 and 2 below show the indices of the hardness of each vulcanized rubber when the hardness of the vulcanized rubber of Comparative Example 1 product is used as a reference (100).
That is, the hardness index of the vulcanized rubber was calculated by the following formula.
Hardness index = (hardness of each vulcanized rubber (type A)) / (reference vulcanized rubber of Comparative Example 1 hardness (type A)) × 100
In Tables 1 and 2 described below, when the hardness index exceeds 90, it was evaluated as ◯ because the physical properties were improved, and when the hardness index was 90 or less, as the physical properties were deteriorated and evaluated as x. .

<Compression set>
The rubber composition was heated at 160 ° C. for 15 minutes, and the vulcanized rubber thus obtained was subjected to a compression set test in accordance with JIS K6262. As the compression set test, two types of tests were performed, a low temperature test of -40 ° C and a high temperature test of 150 ° C. First, in a low temperature test of −40 ° C., vulcanized rubber was compressed at a compression rate of 25%, left in that state for 24 hours at −40 ° C., then the compression was released, and 30 minutes at the same temperature was elapsed. After that, the thickness of the vulcanized rubber was measured, and the compression set (%) was calculated. On the other hand, in the high temperature test of 150 ° C., the vulcanized rubber was compressed at a compression rate of 25% and left in that state for 72 hours at 150 ° C., then the compression was released and 30 minutes passed at room temperature (25 ° C.). After that, the thickness was measured and the compression set was calculated.
In Tables 1 and 2 below, the compression set at low temperature (-40 ° C x 24 hours) or high temperature (150 ° C x 72 hours) is the compression of the vulcanized rubber of Comparative Example 1 product. The index of the compression set of each vulcanized rubber when the set is set as the standard (100) is shown.
That is, the index of compression set was calculated by the following formula.
Compression set index = (compression set of each vulcanized rubber (%)) / (reference set of compression set of vulcanized rubber of Comparative Example 1) x 100
Then, in Tables 1 and 2 described later, the case where the compression set was 110 or less was evaluated as ◯, and the case where the compression set was larger than 110 was evaluated as x.

≪Comprehensive evaluation≫
In the evaluation of each of the above characteristics, the case of all ○ was set as the comprehensive evaluation ○, and the case of at least one × in the evaluation of each characteristic was set as the comprehensive evaluation ×.

  From the results in the above table, the vulcanized rubbers (sealing members) of the examples maintain good mechanical properties (hardness) and also have good compression set (sagging resistance) at low and high temperatures. Moreover, since the Mooney viscosity of the forming material (rubber composition after kneading) is low, the injection property during injection molding is also good, and the processability is also excellent.

  On the other hand, the vulcanized rubber of Comparative Example 1 uses only solid EPDM as a polymer and has poor injection properties during injection molding. In the vulcanized rubber of Comparative Example 2, only solid EPDM was used as a polymer, and the injection property at the time of injection molding was improved by increasing the amount of paraffin oil, but the hardness and the low temperature compression set were deteriorated. In the vulcanized rubber of Comparative Example 3, only solid EPDM was used as the polymer, and the injection property during injection molding was improved by compounding PAO, but the hardness and the low temperature compression set deteriorated. In Comparative Examples 4 and 5, an attempt was made to improve the injection property at the time of injection molding by increasing the proportion of liquid EPDM, but since the kneading process before injection molding could not be performed, further evaluation of characteristics is performed. I couldn't.

  The fuel cell seal member of the present invention is a fuel cell seal body in which a fuel cell constituent member such as a metal separator and a rubber seal member that seals the same are bonded via an adhesive layer, or the above seal member. It is used for the above-mentioned sealing member of a fuel cell sealing body, which is bonded to each other via an adhesive layer.

1 cell 2 MEA
3 Gas diffusion layer 4a Seal member 4b Lip 5 Separator 6 Adhesive layer 7 Gas flow path

Claims (3)

A method for producing a fuel cell sealing member as shown in (α) below, which comprises the following components (A) to (D) and has a content ratio of the components (A) and (B): The ratio is A / B = 95/5 to 40/60, and the content of the component (C) is 0.4 to 12 parts by weight with respect to 100 parts by weight of the total amount of the components (A) and (B). Parts, and a step of kneading the rubber composition in which the content of the component (D) is 5 to 40 parts by weight, and a step of performing injection molding of the kneaded rubber composition. And a method for manufacturing a seal member for a fuel cell.
(Α) A fuel cell sealing member used for sealing a component member of a fuel cell, comprising the following components (A) to ( D ) and containing (A) component and (B) component: content ratio, by weight, ranging der of a / B = 95 / 5~40 / 60 is, relative to 100 parts by weight of the total of components (a) and (B), the content of the component (C) 0.4 to 12 parts by weight and, (D) component fuel cell sealing member ing from the crosslinked product of the rubber composition content of 5 to 40 parts by weight of.
(A) d styrene - propylene - Jiengo nothing Ranaru solid rubber.
(B) a liquid form ethylene - propylene - Jiengo nothing Ranaru liquid rubber.
(C) A crosslinking agent composed of an organic peroxide.
(D) At least one of paraffin oil and poly-α-olefin compound. The method for producing a seal member for a fuel cell according to claim 1, wherein the liquid rubber (B) is a liquid ethylene-propylene-diene rubber having a diene content of 4% by weight or more. Content of the components (A) and component (B), the weight ratio, A / B = Ru 95 / 5-65 / 35 range der of, according to claim 1, wherein the fuel cell sealing member Manufacturing method .

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