JP2015002029A - Resin composition for solid polymer fuel cell sealing material, sealing material for solid polymer fuel cell using the resin composition, and solid polymer fuel cell using the sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for a solid polymer fuel cell sealing material, good in heat resistance, hot water resistance and acid resistance.SOLUTION: A resin composition of a sealing material 16 for a solid polymer fuel battery cell 10 contains a copolymer resin which is obtained through copolymerization of a raw material component including (a) 20 mass% or more of methyl methacrylate and (b) 20 mass% or less of glycidyl-methacrylate and has a weight average molecular weight of 300,000 or more. Preferably, the raw material component furthermore contains (c) one or more other polymerizable monomers selected from hydroxyalkyl alkyl methacrylate and alkyl methacrylate.

Description

  The present invention relates to a resin composition for a polymer electrolyte fuel cell seal material, a seal material for a polymer electrolyte fuel cell using the resin composition, and a polymer electrolyte fuel cell using the seal material. .

A polymer electrolyte fuel cell (hereinafter sometimes referred to as a “fuel cell”) is a fuel gas containing hydrogen and an oxidant gas containing oxygen that is reacted electrochemically with electric power. It generates heat at the same time.
FIG. 1 shows a cross-sectional view of a cell 10 that is a structural unit of a general fuel cell. A general fuel cell is configured by stacking tens to hundreds of cells 10, sandwiching the stacked body between end plates via a current collector plate and an insulating plate, and fastening them from both ends with fastening bolts. .
The fuel cell thus configured operates in a high-temperature and high-humidity state, and hydrofluoric acid is eluted in a trace amount from a solid polymer electrolyte membrane (hereinafter also referred to as “electrolyte membrane”). Therefore, in order to withstand such conditions, the sealing material 16 is required to have heat resistance, hot water resistance, and acid resistance.
As such a sealing material, means of Patent Documents 1 to 5 have been proposed.

JP-A-6-119930 JP 2010-20964 A JP 2002-42835 A JP 2000-56694 A JP 2008-171667 A

  Patent Document 1 uses an O-ring as a sealing material. However, in Patent Document 1, it is necessary to process a groove for fitting an O-ring into the separator, and it is difficult to reduce the thickness of the structure. Further, a large tightening force is required, and the separator is damaged by the force. There was a problem.

Although Patent Documents 2 to 5 do not use an O-ring, there are no problems as described above, but there are the following problems.
Patent Document 2 uses, as a sealing material, alkali metal-containing amorphous silica particles whose carbon content C / Si has been reduced by decarbonization treatment. However, the sealing material of Patent Document 2 has an extremely high fusion temperature of 770 ° C. or higher, and requires a large facility for heating for the sealing work, and lacks versatility.
Patent Document 3 uses urethane resin or liquid silicone rubber as a sealing material. However, the urethane resin has a problem of causing hydrolysis in a high humidity environment. Polyurethane resins are broadly classified into polyester and polyether types, and both are weak to heat. The polyester type is less than 100 ° C, and the polyether type is about 70 ° C, resulting in a decrease in adhesive strength. It was. Liquid silicon rubber has a problem that it has low mechanical strength and is easily hydrolyzed by acid or alkali.
Patent Document 4 uses an olefin resin or a soft epoxy resin as a sealing material. However, an olefin resin has a problem in that a sufficient cohesive force cannot be obtained because the cohesive force of the resin is reduced in a high temperature environment, and a soft epoxy resin has a problem that the adhesive force is reduced by softening in a high temperature environment. It was.
Patent document 5 uses the composition containing a styrene-type block polymerization elastomer and a tackifier as a sealing material. However, the composition has a lower adhesive strength in a high temperature environment.

  A problem to be solved by the present invention is a resin composition for a polymer electrolyte fuel cell sealing material that suppresses a decrease in adhesive strength under a high temperature environment and suppresses deterioration due to hot water or an acid, and the resin composition An object of the present invention is to provide a sealing material for a polymer electrolyte fuel cell using the product, and a polymer electrolyte fuel cell using the sealing material.

A resin composition for a polymer electrolyte fuel cell seal material of the present invention, a seal material for a polymer electrolyte fuel cell using the resin composition, and a polymer electrolyte fuel cell using the seal material are as follows: [1] to [8].
[1] A copolymer resin having a weight average molecular weight of 300,000 or more obtained by copolymerizing (a) a raw material component containing 20% by mass or more of methyl methacrylate and (b) 20% by mass or less of glycidyl (meth) acrylate. A resin composition for a polymer electrolyte fuel cell sealing material, comprising:
[2] The resin composition for a polymer electrolyte fuel cell sealing material according to the above [1], wherein the epoxy equivalent of the copolymer resin is 710 to 1430000 g / eq.
[3] The above [1] or [2], wherein the raw material component further contains at least one polymerizable monomer selected from (c) hydroxyalkyl (meth) acrylate and alkyl (meth) acrylate. A resin composition for a polymer electrolyte fuel cell sealing material according to 1.
[4] The polymer electrolyte fuel cell seal according to any one of [1] to [3], wherein the resin composition further contains a curing agent having a functional group capable of reacting with a glycidyl group. Resin composition for materials.
[5] The solid polymer fuel cell sealing material according to any one of [1] to [4], wherein a nitrogen atom contained in the resin composition is 0.04% or less on a mass basis. Resin composition.
[6] A sealing material for a polymer electrolyte fuel cell, which is formed from the resin composition according to any one of [1] to [5].
[7] A solid polymer type obtained by sandwiching both surfaces of a sheet-like sealing material layer formed from the resin composition according to any one of [1] to [5] above with a peelable substrate. Sealing material for fuel cells.
[8] A solid polymer fuel cell comprising a sealing portion by the solid polymer fuel cell sealing material according to [6].
Hereinafter, the resin composition for the polymer electrolyte fuel cell sealing material of the present invention is referred to as “the resin composition of the present invention”, and the seal for the polymer electrolyte fuel cell using the resin composition of the present invention. The material may be referred to as “the sealing material of the present invention”, and the polymer electrolyte fuel cell using the sealing material of the present invention may be referred to as “the fuel cell of the present invention”.

  The resin composition and sealing material of the present invention can maintain the cohesive strength of the resin in a high-temperature environment and suppress a decrease in adhesive strength, and further prevent deterioration due to moisture and acid. Can be stabilized. In addition, the fuel cell of the present invention can suppress the peeling or deterioration of the sealing material, and can stabilize the performance of the fuel cell over time.

Sectional drawing which shows an example of the cell which comprises a general fuel cell Illustration of measuring shear strength

[1] Resin composition for polymer electrolyte fuel cell sealing material The resin composition of the present invention comprises (a) 20% by mass or more of methyl methacrylate and (b) 20% by mass or less of glycidyl (meth) acrylate. A component is copolymerized to contain an acrylic copolymer resin having a weight average molecular weight of 300,000 or more.
In the present invention, the weight average molecular weight is a value measured by gel permeation chromatogram method and converted to polystyrene.

(A) Methyl methacrylate Methyl methacrylate (methyl methacrylate monomer) is contained in an amount of 20% by mass or more in the raw material component of the copolymer resin. By setting the methyl methacrylate to 20% by mass or more, it is possible to prevent the copolymer resin from being decomposed by hot water or an acid and reducing its weight, and to suppress a decrease in adhesive strength under a high temperature environment. Further, by containing 20% by mass or more of methyl methacrylate, it is possible to increase the softening point of the copolymer resin and improve the handleability when used as a sealing material.
In addition, it is preferable that methyl methacrylate shall be 80 mass% or less in the raw material component of copolymer resin. By making methyl methacrylate 80% by mass or less, the ratio of (b) glycidyl (meth) acrylate, which will be described later, is secured, and the decrease in adhesive strength in a high temperature environment is further suppressed, and the acid resistance is further improved. Can do.
The ratio of methyl methacrylate is more preferably 30 to 70% by mass, and further preferably 40 to 60% by mass.

(B) Glycidyl (meth) acrylate Glycidyl (meth) acrylate (glycidyl (meth) acrylate monomer) is contained in an amount of 20% by mass or less in the raw material component of the copolymer resin. By containing glycidyl (meth) acrylate, the cohesive strength of the resin can be ensured while maintaining the adhesive strength in a high temperature environment. Moreover, by setting the content ratio of glycidyl (meth) acrylate to 20% by mass or less, it is possible to prevent gelation of the copolymer resin and secure the ratio of methyl methacrylate to improve the hot water resistance and acid resistance. it can.
The content ratio of glycidyl (meth) acrylate is preferably 0.1 to 15% by mass, more preferably 0.5 to 10.0% by mass, and 1.0 to 5.0% by mass. More preferably.
As glycidyl (meth) acrylate, either glycidyl methacrylate or glycidyl acrylate can be used, but glycidyl methacrylate is preferred from the viewpoints of handling properties such as skin irritation, stability as a compound, and ease of synthesis.

(C) Other polymerizable monomer It is preferable that copolymer resin contains 1 or more types of the other polymerizable monomer chosen from hydroxyalkyl (meth) acrylate and alkyl (meth) acrylate in a raw material component.
By containing methyl methacrylate as the component (a), the copolymer resin can have good hot water resistance, acid resistance, and adhesive strength in a high temperature environment, while the softening point of the copolymer resin may be too high. is there. Here, by containing the other polymerizable monomer of the component (c), the softening point of the copolymer resin is lowered, and the workability at the time of heat-sealing the sealing material to the seal portion of the fuel cell is improved. be able to.

Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.
As the alkyl (meth) acrylate, alkyl (meth) acrylates other than methyl methacrylate can be used, and n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) Butyl (meth) acrylate such as acrylate, ethyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate , Isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) ) Acrylate, tridecyl (meth) acrylate.
The other polymerizable monomer is preferably an alkyl (meth) acrylate from the viewpoint of hot water resistance. In addition, alkyl acrylate is preferable from the viewpoint of easy adjustment of the softening point of the copolymer resin. Furthermore, butyl acrylate or ethyl acrylate is preferred from the viewpoint of easy copolymerization and industrial versatility. Moreover, it is also suitable to use butyl acrylate and ethyl acrylate together from the viewpoint of adjusting the softening point.

  The other polymerizable monomer is preferably contained in the raw material component of the copolymer resin in an amount of 5% by mass or more and less than 80% by mass, more preferably 15 to 70% by mass, and more preferably 25 to 60% by mass. Further preferred. By setting the other polymerizable monomer to 5% by mass or more, the softening point of the copolymer resin can be lowered and the heat sealing operation of the sealing material can be facilitated. By setting it to less than 80% by mass, methyl methacrylate And the ratio of glycidyl (meth) acrylate can be ensured, and the adhesive force in a high temperature environment, hot water resistance, and acid resistance can be made favorable.

  The copolymer resin is obtained by copolymerizing a raw material composition containing (a) methyl methacrylate and (b) glycidyl (meth) acrylate described above, and (c) other polymerizable monomer used as necessary. It will be.

Examples of the copolymerization method include suspension polymerization, emulsion polymerization, and solution polymerization. Among these copolymerization methods, a polymer with a narrow molecular weight distribution and a small amount of residual monomer can be obtained, a polymer with a high molecular weight can be obtained, an emulsifier is not required, so there are few impurities, and water resistance while polymerizing in water. Suspension polymerization is preferable from the viewpoint that a copolymer resin excellent in heat resistance and heat resistance is easily obtained.
For example, in the case of suspension polymerization, the polymerization conditions are preferably 50 to 80 ° C. and 2 to 24 hours.
The form of the copolymer may be any form such as alternating, random, block, or graft.

  In the aqueous suspension polymerization for producing the granules, one or more suspension stabilizers can be used. For example, water-soluble polymers such as polyvinyl alcohol, partially saponified polyvinyl alcohol, polyvinyl pyrrolidone, (meth) acrylate, polyacrylamide, partially saponified polyacrylamide, carboxymethylcellulose, methylcellulose, ethylcellulose, calcium phosphates, calcium carbonate, etc. Examples thereof include inorganic salt powder.

As a polymerization initiator, it is preferable that the polymerization initiation radical species after decomposition is oil-soluble. Typical radical polymerization initiators include azo radical polymerization initiators and peroxide radical polymerization initiators.
As the azo radical polymerization initiator, 2,2′-azobispropane, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2 '-Azobis (2-amidinopropane) hydrochloride, 2,2'-azobis (2-aminopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'- Azobisisobutyronitrile, methyl 2,2′-azobis-2-methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, 2 , 2′-azobisisobutyric acid dimethyl, 1,1′-azobis (sodium 1-methylbutyronitrile-3-sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile 4,4′- Azobis-4 -Cyanovaleric acid, 3,5-dihydroxymethylphenylazo-2-allylmalonodinitrile, 2,2'-azobis-2-methylvaleronitrile, dimethyl 4,4'-azobis-4-cyanovaleric acid, 2, 2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1'-azobiscyclohexanenitrile, 2,2 '-Azobis-2-propylbutyronitrile, 1,1'-azobis-1-chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'-azobis-1-cycloheptanenitrile, , 1′-azobis-1-phenylethane, 1,1′-azobiscumene, 4-nitrophenylazobenzylethyl cyanoacetate, phenylazo Phenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotriphenylmethane, 1,1'-azobis-1,2-diphenylethane, poly (bisphenol A-4,4'-azobis-4-cyanopentanoate ), Poly (tetraethylene glycol-2,2′-azobisisobutyrate) and the like.
Examples of peroxide radical polymerization initiators include acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, 2-chlorobenzoyl peroxide, 3-chlorobenzoyl peroxide, and peroxide 4 -Chlorobenzoyl, 2,4-dichlorobenzoyl peroxide, 4-bromomethylbenzoyl peroxide, lauroyl peroxide, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide , Pertriphenylacetic acid-tert-butyl, tert-butyl hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl benzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, Ex N- (3-Torr Le) carbamic acid tert- butyl and the like. Examples of the polymerization initiator include peroxides such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, and methyl ethyl ketone peroxide.

  Moreover, a mercapto compound can be added as a chain transfer agent. For example, chain transfer agents having hydroxyl groups such as mercaptoethanol, mercaptopropanol, mercaptobutanol, mercaptopropanediol, mercaptobutanediol, hydroxybenzenethiol and derivatives thereof; 1-butanethiol, butyl-3-mercaptopropionate, methyl- 3-mercaptopropionate, 2,2- (ethylenedioxy) diethanethiol, ethanethiol, 4-methylbenzenethiol, dodecyl mercaptan, propanethiol, butanethiol, pentanethiol, 1-octanethiol, cyclopentanethiol, Examples include cyclohexanethiol, thioglycerol, and 4,4-thiobisbenzenethiol.

The weight average molecular weight of the copolymer resin is 300,000 or more. By setting the weight average molecular weight to 300,000 or more, the adhesive strength in a high temperature environment can be improved. The weight average molecular weight of the copolymer resin is preferably 1.5 million or less from the viewpoints of suppressing gelation during polymerization and stabilizing the quality. The weight average molecular weight of the copolymer resin is preferably 400,000 to 1,000,000, and more preferably 500,000 to 800,000.
The primary softening point of the copolymer resin is preferably 80 to 150 ° C, and more preferably 100 to 140 ° C. By setting the softening point to 100 ° C. or higher, adhesiveness in a high temperature environment can be secured, and by setting it to 150 ° C. or lower, fluidity at the time of joining by hot pressing or the like can be secured. The softening point can be measured by the method described in the examples.
The epoxy equivalent of the copolymer resin is preferably 710 to 1430000 g / eq, more preferably 950 to 143000 g / eq, further preferably 1420 to 28600 g / eq, and 2840 to 14300 g / eq. It is even more preferable. By setting the epoxy equivalent to 1430000 g / eq or less, adhesiveness under a high temperature environment can be secured, and by setting it to 710 g / eq or more, the cohesive strength of the resin can be increased while securing the adhesiveness under a high temperature environment. . The epoxy equivalent can be measured by titration.

  The copolymer resin is preferably contained in an amount of 50% by mass or more, more preferably 60% by mass or more, based on the total solid content of the resin composition of the present invention, in order to sufficiently exert the effects of the present invention. 80% by mass or more, more preferably 90% by mass or more.

(Curing agent having functional group capable of reacting with glycidyl group)
The resin composition of the present invention may contain a curing agent having a functional group capable of reacting with a glycidyl group (hereinafter sometimes referred to as “glycidyl curing agent”). By containing a glycidyl curing agent, the decrease in adhesive strength under high temperature environment is suppressed, and the resin composition is prevented from degrading and weight loss under high temperature environment, and the performance of the fuel cell is stably maintained. be able to.

As the glycidyl curing agent, polyamine, polyphenol, acid anhydride, polysulfiso, boron trifluoride and the like are preferably used.
Examples of polyamines include 4,4′-diaminodiphenylmethane, 4,4′-didiaminodiphenylsulfone, metaphenylenediamine, 4,4′-diamino-3,3′-didiethyl-5,5′-di4. , 4'-didimethyldiphenylmethane, 3,3'-didimethoxy-4,4'-didiaminodiphenyl, 3,3'-didimethyl-4,4'-di-4,4'-didiaminodiphenyl, 2,2 '-Dichloro-4,4'-didiamino-5,5'-didimethoxydimethyl, 2,2', 5,5'-tetrachloro-4,4'-didiaminodiphenyl, 4,4'-dimethylenebis (2 -Chloroaniline), 2,2 ', 3,3'-tetrachloro-4,4'-didiaminodiphenylmethane, 4,4'-didiaminodiphenyl ether, 4,4'-didiaminobenzanilide, 3, , 3'-jijihi Droxy-4,4′-didiaminobiphenyl, 9,9′-dibis (4-aminophenyl) fluorene, 9,9′-dibis (4-aminophenyl) anthracene, ethylenediamine, diethylaminopropylamine, hexamethylenediamine, isophorone Examples thereof include diamine and bis (4-amino-3-methylcyclohexyl) methane.
Examples of polyphenols include phenol novolak, o-cresol novolak, p-cresol novolak, pt-butylphenol novolak, hydroxynaphthalene novolak, bisphenol A novolak, bisphenol F novolak, terpene modified phenol, terpene modified novolak, dicyclopentadiene. Modified novolak, paraxylene modified novolak, polybutadiene modified phenol and the like.
Examples of the acid anhydride include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, nadic anhydride, and chlorendic anhydride.
Among glycidyl curing agents, polyphenols are preferable from the viewpoint of preventing elution of ammonium ions. In particular, the terpene-modified phenol is preferable in that it not only suppresses a decrease in adhesive strength under a high temperature environment but also increases the adhesive strength under a high temperature environment.

When using a glycidyl hardening | curing agent, it is preferable to contain 0.1 mass% or more of the total solid of the resin composition of this invention. By containing 0.1% by weight or more, adhesiveness under a high temperature environment can be maintained, and it is easy to prevent the resin composition from deteriorating under a high temperature environment and reducing the weight of the resin. On the other hand, if there is too much glycidyl curing agent, the glycidyl curing agent itself may be eluted due to the influence of heat or acid. For this reason, the content of the glycidyl curing agent is more preferably 0.5 to 50% by mass, further preferably 1 to 20% by mass, and further preferably 2 to 10% by mass.
In addition, when using a glycidyl hardening | curing agent in addition to a copolymer resin, after mixing a glycidyl hardening | curing agent with a copolymer resin, it is preferable to heat on the conditions for about 1 to 5 minutes at 100-170 degreeC.

(Other additives)
The resin composition of the present invention contains additives such as pigments, flame retardants, ultraviolet absorbers, antioxidants, antistatic agents, silane coupling agents, and tackifiers, as long as the effects of the present invention are not impaired. May be.

In the resin composition of the present invention, the nitrogen atoms contained in the total solid content of the resin composition are preferably 0.04% or less on a mass basis. By setting the nitrogen atom to 0.04% or less, it is possible to prevent the cation from eluting from the sealing material and to prevent the performance of the fuel cell from being affected. The nitrogen atom in the copolymer resin is more preferably 0.02% or less, and still more preferably not contained. In the present invention, a nitrogen atom of 0.001% or less is defined as not containing a nitrogen atom.
Usually, an amine curing agent is used in combination with a resin having a glycidyl group. However, in the present invention, it is preferable not to use an amine curing agent in order to suppress the amount of nitrogen atoms.
The amount of nitrogen atoms in the copolymer resin can be measured by, for example, an organic trace element analyzer such as trade name JM1000CN manufactured by J Science Lab.

[Sealant for polymer electrolyte fuel cells]
The sealing material of the present invention is formed from the above-described resin composition of the present invention. The form of the sealing material is preferably a solid such as a particle or sheet.
Further, the sealing material of the present invention has a form in which the surfaces on both sides of the sheet-shaped sealing material layer formed from the above-described resin composition of the present invention are sandwiched by a peelable base material from the viewpoint of handleability. Is preferred.
When the sealing material is formed in a sheet shape, the thickness of the sealing material layer varies depending on the separator of the fuel cell, the electrolyte membrane, and the like, and thus cannot be generally specified, but is preferably 10 to 500 μm, more preferably 20 to 200 μm. In addition, you may laminate the sealing material layer as needed.

The releasable base material can be released from plastic films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polystyrene, triacetylcellulose, poly (meth) acrylate, polyvinyl chloride, and paper. Those subjected to are suitable.
The peelable substrate is preferably 10 to 100 μm and more preferably 25 to 75 μm from the viewpoint of handleability. The peelable substrate is preferably a non-silicone-based substrate in order to prevent adverse effects due to the migration of the silicone component to the electrolyte membrane and the sealing material layer. Examples of the non-silicone peelable substrate include a substrate whose surface is treated with polyolefin.

  Such a sealing material of the present invention can be used for a sealing part of a fuel cell, more specifically, a sealing part of a cell constituting the fuel cell. In use, the sealing material is heated and melted to seal the sealing portion of the cell. In addition, what was inserted | pinched with the base material which can peel a sealing material layer should just heat and fuse a sealing material layer, and should seal the sealing part of a cell, after peeling a base material.

[Polymer fuel cell]
The fuel cell of the present invention is provided with a sealing portion by the sealing material of the present invention.
FIG. 1 is a cross-sectional view showing an example of a cell constituting a general fuel cell.
The cell 10 is a composite (MEA: Membrane and Electrode Assembly) composed of a solid polymer electrolyte membrane 11 and a pair of electrodes (anode, cathode) 12 and 13 disposed on both sides thereof, and is disposed on both sides of the complex. The separator (14, 15) in which gas flow paths (14a, 15a) for supplying the fuel gas and the oxidant gas are formed, and the space between the composite and the separator (14, 15) is sealed. It is comprised from the sealing material 16 which seals suitably.
A general fuel cell is configured by stacking tens to hundreds of cells 10, sandwiching the stacked body between end plates via a current collector plate and an insulating plate, and fastening them from both ends with fastening bolts. .
The fuel cell of the present invention uses the above-described sealing material of the present invention as a sealing material in such a general fuel cell. In addition, the position (seal | sticker site | part) of the sealing material of FIG. 1 is an illustration, The position of a sealing material can be suitably changed with the structure of the cell which comprises a fuel cell.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following examples.

The following evaluation was performed about the resin composition for fuel cell sealing materials obtained by the following examples and comparative examples. In addition, since Comparative Examples 1, 2, 4, and 5 all lack adhesive strength in a high-temperature environment, other evaluations were performed with the minimum necessary. Since Comparative Example 3 has ion elution, other evaluations were performed with the minimum necessary. Moreover, about the Example, although all the items were evaluated about Example 1 and 8 which are typical Examples, evaluation of the other examples performed minimum necessary evaluation.
<Adhesive strength (room temperature, 120 ° C.)>
A 5 cm × 5 cm polyethersulfone sheet (thickness 0.2 mm) and an electrolyte membrane (DuPont, Nafion NRE-212, thickness 50 μm) are sandwiched with a 1 cm × 5 cm sealing material, conditions of 0.05 MPa and 170 ° C. For 1 minute. After press bonding, the strip is cut into a 1.5 cm width and left at room temperature or 120 ° C. for 1 minute, and then the polyimide tape is reinforced on the entire surface on the electrolyte membrane side. The film was pulled with Tensilon under the conditions of ° and speed of 10 mm / min, and the peel strength was measured. In addition, the thickness of the sealing material of Examples 1-8 and Comparative Examples 1-4 was 50 micrometers. The thickness of the sealing material of Comparative Example 5 was 30 μm. The results are shown in Table 2.
<Shear strength (cohesive strength)>
As shown in FIG. 2, a 3 mm × 50 mm sealing material was sandwiched between two 50 mm × 50 mm SUS plates, and press-bonded for 1 minute under the conditions of 0.15 MPa and 170 ° C. After press joining, cut into a strip with a width of 10 mm, let stand at room temperature for more than 1 minute, fix SUS on one side, pull the other SUS plate with Tensilon at a speed of 200 mm / min, and measure the shear strength did. In addition, the thickness of the sealing material of Examples 1-3 and 8 was 50 micrometers. The results are shown in Table 2.

<Weight change (due to hot water)>
Deionized water is put into a heat-resistant container, and a 5 cm × 5 cm sealing material is immersed therein. The container was put into an oven at 95 ° C., a sample was taken out after a predetermined time, and the weight change was measured with an electronic balance. The measurement was performed after 100 hours, 300 hours, 500 hours, 750 hours, 1000 hours and 1500 hours, and the ratio to the initial weight was calculated. In addition, the thickness of the sealing material of Examples 1 and 8 was 150 μm. The results are shown in Table 3.
<Weight change (due to acid)>
A sulfuric acid solution having a pH of 2.0 is put into a heat-resistant container, and hydrogen fluoride is added so as to have a concentration of 30 ppm, and then a 5 cm × 5 cm sealing material is immersed therein. The container was put into an oven at 95 ° C., a sample was taken out after a predetermined time, and the weight change was measured with an electronic balance. The measurement was performed after 100 hours, 300 hours, 500 hours, 750 hours, 1000 hours and 1500 hours, and the ratio to the initial weight was calculated. In addition, the thickness of the sealing material of Examples 1 and 8 was 150 μm. The results are shown in Table 3.
<Weight change (caused by heat: 120 ° C.)>
A 5 cm × 5 cm sealing material was put into a 120 ° C. oven close to the environment in which the fuel cell was used, a sample was taken out after a predetermined time, and the weight change was measured with an electronic balance. The measurement was performed after 100 hours, 300 hours, 500 hours, 750 hours, 1000 hours and 1500 hours, and the ratio to the initial weight was calculated. In addition, the thickness of the sealing material of Examples 1 and 8 was 150 μm. The results are shown in Table 3.

<Weight change (caused by heat: 200 ° C.)>
A 5 cm × 5 cm sealing material was put into an oven at 200 ° C., a sample was taken out after a predetermined time, and the change in weight was measured with an electronic balance. The measurement was performed after 5 minutes, 15 minutes, 30 minutes, 60 minutes, and 120 minutes, and the ratio to the initial weight was calculated. In addition, the thickness of the sealing material of Example 1 and 8 was 50 micrometers. The thickness of the sealing material of Comparative Example 5 was 30 μm. The results are shown in Table 4.

<Ion elution (electrolyte membrane contamination)>
Deionized water is put into a heat-resistant container, and a 5 cm × 5 cm electrolyte membrane (manufactured by DuPont, Nafion NRE-212) and a sealing material cut into a size of 5 cm × 5 cm are immersed therein. The container was put into an oven at 95 ° C., and after 200 hours, the electrolyte membrane was taken out of the container and visually checked for coloration. An uncolored product was designated as “◯”, and a red product was designated as “X”. In addition, the thickness of the sealing material of Examples 1-8 and Comparative Examples 1-4 was 50 micrometers. The thickness of the sealing material of Comparative Example 5 was 30 μm. The results are shown in Table 2.
<Ion elution (elution amount)>
50 g of deionized water is put into a heat-resistant container, and about 2 g of a sealing material layer cut into a size of 1 cm × 5 cm is added, and the container is heated in an oven at 120 ° C. for 24 hours. Using the solution in the container as a test solution, the ion elution amount of ammonium ions and the like was measured by ion chromatography to calculate the ion content in the sealing material. In addition, the thickness of the sealing material of Examples 1-8 and Comparative Examples 1-4 was 50 micrometers. The results are shown in Table 2.
<Nitrogen content>
The total nitrogen content of the resin compositions of Examples 1 and 8 was quantified using an organic trace element analyzer (JM1000CN, manufactured by J Science Laboratories). The results are shown in Table 2.
<Softening point>
The primary softening points of the copolymer resins of Examples 1, 7, 8 and Comparative Example 4 were measured with a thermomechanical analyzer. The results are shown in Table 1.

[Example 1]
(Synthesis of copolymer resin)
In a separable flask having a volume of 1 liter, 200 parts by mass of water containing 0.2% by mass of polyvinyl alcohol, (a) 45 parts by mass of methyl methacrylate monomer, (b) 3 parts by mass of glycidyl methacrylate monomer, (c ) A homogeneous mixed solution containing 42 parts by mass of butyl acrylate monomer, 10 parts by mass of ethyl acrylate monomer, 0.1 part by mass of benzoyl peroxide as a polymerization initiator, and a chain transfer agent for adjusting the molecular weight was added.
The mixture was heated to 70 ° C. with stirring in a nitrogen atmosphere and subjected to suspension polymerization for 4 hours. The water was then removed from the suspension by decantation. The solid was washed with water while suction filtration, and the water was removed, followed by vacuum drying at 60 ° C. to obtain a copolymer resin (resin composition of Example 1) having a water content of 0.5% or less.
When the weight average molecular weight of the obtained copolymer resin was measured by the method of measuring the weight average molecular weight, it was about 650,000. The monomer composition and molecular weight are shown in Table 1.

(Production of sheet-like sealing material)
The obtained copolymer resin was melted and stirred in methyl ethyl ketone to prepare a sealing material layer forming composition. The sealing material layer forming composition was applied to a 75 μm-thick polyester film having been subjected to the mold release treatment and dried to form a sealing material layer. A sealing material layer having a thickness of 50 μm and a thickness of 150 μm were prepared. The drying condition of 50 μm thickness was 100 ° C. for 2 minutes, and the drying condition of 150 ° C. thickness was 100 ° C. for 5 minutes.
Next, a release-treated polyester film having a thickness of 25 μm was bonded to the sealing material layer to obtain a sheet-shaped sealing material.

[Examples 2-7, Comparative Examples 1-3]
A resin composition and a sheet-like sealing material were obtained in the same manner as in Example 1 except that the composition of the raw material monomer of the copolymer resin and the weight average molecular weight of the copolymer resin were as shown in Table 1. In addition, the weight average molecular weight of each Example and the comparative example was adjusted with the quantity of the chain transfer agent.

[Example 8]
3 parts by mass of a terpene-modified phenol resin (YShara Chemical Co., Ltd., YS Polystar G150) was added to 97 parts by mass of the copolymer resin of Example 1 to obtain a resin composition of Example 8. Next, in the same manner as in Example 1, a sheet-like sealing material was obtained.

[Comparative Example 4]
The trade name PHY-3E manufactured by Nippon Kayaku Co., Ltd., which is a soft epoxy resin, was used as the resin composition. Further, using the resin composition, a sheet-like sealing material was obtained in the same manner as in Example 1.

[Comparative Example 5]
A commercially available polyester polyurethane resin sheet having a thickness of 30 μm was used as the sealing material of Comparative Example 5.

From the result of Table 2, it can confirm that the resin composition of Examples 1-8 can suppress the fall of the adhesive force in a high temperature environment, and there is no elution of ion. It can also be confirmed that as the amount of glycidyl methacrylate increases, the shear strength of the resin composition increases, that is, the cohesive strength of the resin composition increases.
On the other hand, the resin compositions of Comparative Examples 1 to 5 cannot suppress a decrease in adhesive strength under a high temperature environment. Further, in Comparative Examples 3 and 4, the ions were violently eluted.

  From the results of Table 3, it can be confirmed that the resin compositions of Examples 1 and 8 can suppress a decrease in weight due to hot water, acid, and heat (120 ° C.). In particular, it can be confirmed that the resin composition of Example 8 containing a glycidyl curing agent in the resin composition is extremely excellent in suppressing weight change caused by heat.

  From the results in Table 4, it can be confirmed that the resin compositions of Examples 1 and 8 can suppress weight reduction even in a temperature environment (200 ° C.) exceeding the use environment (about 120 ° C.) of the fuel cell. On the other hand, the thing of the comparative example 5 which used the urethane resin as a resin composition was a thing which cannot suppress the weight change resulting from a heat | fever.

[Example 9]
A resin composition and a sheet-like sealing material of Example 9 were obtained in the same manner as in Example 8, except that the ratio of the copolymer resin and the terpene-modified phenol resin was changed to 90:10.

[Example 10]
A resin composition and a sheet-like sealing material of Example 10 were obtained in the same manner as in Example 8, except that the ratio of the copolymer resin and the terpene-modified phenol resin was changed to 80:20.

[Example 11]
A resin composition and a sheet-like sealing material of Example 11 were obtained in the same manner as in Example 8, except that the ratio of the copolymer resin and the terpene-modified phenol resin was changed to 70:30.

The following evaluation was performed about the sealing material of Example 1, 8-11.
<Adhesive strength (room temperature, 120 ° C.)>
A 1 cm × 5 cm × 50 μm-thick sealing material is sandwiched between a 5 cm × 5 cm polyethersulfone sheet (thickness 0.2 mm) and an electrolyte membrane (manufactured by DuPont, Nafion NRE-212, thickness 50 μm). Press bonding was performed at a temperature of 1 ° C. for 1 minute. After press bonding, the strip is cut into a 1.5 cm width and left at room temperature for 1 minute, and then the polyimide tape is reinforced on the entire surface on the electrolyte membrane side. The polyimide tape and the electrolyte membrane are rotated at an angle of 180 ° and a speed of 50 mm / The film was pulled with Tensilon under the condition of min, and the peel strength was measured. The results are shown in Table 5.
<Weight change (caused by heat: 200 ° C.)>
A sealing material having a thickness of 5 cm × 5 cm × 50 μm was placed in an oven at 200 ° C., a sample was taken out after a predetermined time, and the weight change was measured with an electronic balance. The measurement was performed after 5 minutes, 15 minutes, 30 minutes, 60 minutes, and 120 minutes, and the ratio to the initial weight was calculated. The results are shown in Table 5.

  From the results of Table 5, the examples 8 to 11 containing a glycidyl curing agent (terpene-modified phenol) in the resin composition increase the effect of suppressing the weight change caused by heat, and adhere in a high-temperature environment. It can be confirmed that the force increases.

10: Cell 11: Electrolyte membrane 12, 13: Electrodes 14, 15: Separator 14a, 15a: Gas flow path 16: Sealing material 2: SUS plate

Claims (8)

  (A) It contains a copolymer resin having a weight average molecular weight of 300,000 or more, which is obtained by copolymerizing a raw material component containing 20% by mass or more of methyl methacrylate and 20% by mass or less of (b) glycidyl (meth) acrylate. A resin composition for a polymer electrolyte fuel cell sealing material.   The resin composition for a polymer electrolyte fuel cell sealing material according to claim 1, wherein an epoxy equivalent of the copolymer resin is 710 to 1430000 g / eq.   The solid polymer according to claim 1 or 2, wherein the raw material component further contains one or more polymerizable monomers selected from (c) hydroxyalkyl (meth) acrylate and alkyl (meth) acrylate. Resin composition for type fuel cell sealing material.   The resin composition for a polymer electrolyte fuel cell sealing material according to any one of claims 1 to 3, further comprising a curing agent having a functional group capable of reacting with a glycidyl group in the resin composition. .   The resin composition for a polymer electrolyte fuel cell sealing material according to any one of claims 1 to 4, wherein a nitrogen atom contained in the resin composition is 0.04% or less on a mass basis.   A sealing material for a polymer electrolyte fuel cell, which is formed from the resin composition according to claim 1.   6. A sealing material for a polymer electrolyte fuel cell, wherein both sides of a sheet-like sealing material layer formed from the resin composition according to claim 1 are sandwiched between detachable substrates. .   A polymer electrolyte fuel cell comprising a seal portion by the polymer electrolyte fuel cell sealing material according to claim 6.

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