Sub gasket material for polymer electrolyte fuel cells

Abstract

The hot melt adhesive sheet of the present invention comprises a substrate and an adhesive layer formed by a hot melt adhesive and deposited on at least one side of the substrate. The hot melt adhesive comprises a crosslinked adhesive composition containing a crosslinking agent. The adhesive composition comprises a polyurethane resin, an epoxy resin and an isocyanate-based crosslinking agent. The polyurethane resin comprises a polyester polyurethane resin having an aromatic polyester backbone. The epoxy resin comprises an unmodified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less.

Description

Technical Field

[0001] The present invention relates to a hot melt adhesive sheet. Prior Art

[0002] In the past, as an adhesive for various plastics, considering the adhesion stability in a low temperature region (for example, -10°C to 15°C) and the adhesiveness, flexibility, processability, and ease of various molecular designs in a normal temperature region (25 ± 10°C), a polyurethane-based adhesive was mostly used. Regarding the aforementioned polyurethane-based adhesive, it has the following two types: one contains polyester polyol or acrylic polyol as the main agent and polyisocyanate as the crosslinking agent, and a urethane bond is formed by carrying out a crosslinking reaction between the main agent and the crosslinking agent for use; the other contains a polyurethane having a certain chain length (so-called polyurethane prepolymer) as the main agent and an isocyanate-based crosslinking agent as the crosslinking agent, and it is hardened by carrying out a crosslinking reaction between the main agent and the crosslinking agent for use.

[0003] Also, Patent Document 1 below describes an adhesive excellent in heat and humidity resistance as a two-component adhesive containing a polyurethane resin as the main agent and containing an epoxy resin and an isocyanate-based crosslinking agent. In recent years, from the viewpoint of excellent operability, the opportunity to use a hot melt adhesive for bonding members has increased compared to the liquid adhesive described in Patent Document 1 below. Regarding the aforementioned hot melt adhesive, especially from the viewpoint of excellent operability, it is mostly used in the form of a hot melt adhesive sheet. The aforementioned hot melt adhesive sheet usually includes a base material layer formed of a polymer sheet and an adhesive layer laminated on the base material layer and formed of the aforementioned hot melt adhesive. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2013 / 157604 Summary of the Invention Problems to be Solved by the Invention

[0005] Not only the two-component adhesive described in Reference Document 1, but also the adhesive layer of the hot melt adhesive sheet is required to achieve an improvement in heat and humidity resistance (hot water resistance).

[0006] Also, although the requirements for the adhesive layer of hot-melt adhesive sheets to improve acid resistance, alcohol resistance, etc., such a demand has not been met. Furthermore, the adhesive layer of the hot-melted adhesive sheet is also required to have characteristics that can ensure adequate closeness with the adherent by means of hot pressing.

[0007] The present invention is completed in view of the problem points possessed by such a previous technique, the subject of which is to provide a hot-melt adhesive sheet having an adhesive layer with excellent adhesion to the attached object and excellent heat resistance, acid resistance, and alcohol resistance. Lesson を Solving するための means

[0008] The hot-melt adhesive sheet of the present invention has a substrate and an adhesive layer formed by the hot-melt adhesive and layered on at least one side of the preceding substrate, The preceding hot-melt adhesive contains a crosslink comprising an adhesive composition of the crosslinker, wherein, the preceding adhesive composition contains a polyurethane resin, an epoxy resin, and an isocyanate-based crosslinker, The foregoing polyurethane resin contains a polyester aminoformate resin having an aromatic polyester skeleton, The foregoing epoxy resins contain non-modified epoxy resins with epoxy equivalents above 300g / eq and less than 1500g / eq. The fruit of Mingming Brief explanation of the schema

[0009] is a rough cross-sectional view showing the configuration of a hot-melt clad sheet of one embodiment of the present invention. 2 is a rough cross-sectional view of the state in which a hot-melt clad sheet of one embodiment of the present invention is mounted for use in a solid-state electrolyte film of a solid polymer-type fuel cell. Implementation

[0010] The following illustrates one embodiment of the invention while referring to the diagram. Hereafter, only one embodiment of the invention is sometimes referred to as the present embodiment.

[0011] As shown in FIG. In the hot-melt adhesive sheet 10 shown in FIG. That is, the hot melt adhesive sheet 10 can also be a hot melt adhesive sheet formed by depositing an adhesive layer 10b on both sides of the substrate 10a.

[0012] In the hot melt adhesive sheet 10 of this embodiment, the aforementioned hot melt adhesive contains a crosslinked adhesive composition comprising a crosslinking agent, wherein the aforementioned adhesive composition comprises polyurethane resin, epoxy resin and isocyanate-based crosslinking agent. In the hot-melt adhesive sheet 10 of this embodiment, the aforementioned polyurethane resin contains a polyester polyurethane resin having an aromatic polyester backbone. In the hot-melt adhesive sheet 10 of this embodiment, the aforementioned epoxy resin contains a non-modified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less. Hereinafter, polyurethane resin will be referred to as polyurethane resin (A), epoxy resin as epoxy resin (B), and isocyanate-based crosslinking agent as isocyanate-based crosslinking agent (C).

[0013] (Polyurethane resin (A)) Polyurethane resin (A) is obtained by bonding a reaction component containing a polyol component (a) having two or more hydroxyl groups in one molecule with a polyisocyanate component (b) having two or more isocyanate groups in one molecule with an urethane ester bond.

[0014] As explained above, in the hot melt adhesive sheet 10 of this embodiment, the polyurethane resin (A) contains a polyester polyurethane resin having an aromatic polyester backbone.

[0015] In this specification, the aforementioned polyester urethane resin refers to the product obtained by reacting polyisocyanate component (b) with a hydroxyl-containing polyester (equivalent to the aforementioned polyol component (a)). That is, in this specification, the aforementioned polyester urethane resin refers to the urethane bond between a hydroxyl-containing polyester and the polyisocyanate component (b).

[0016] Regarding the aforementioned hydroxyl-containing polyesters, polyesters obtained by the condensation reaction of polycarboxylic acids and polyols can be used.

[0017] Examples of the aforementioned polycarboxylic acids include: phthalic acid, isophthalic acid, terephthalic acid, maleic acid, itconic acid, fumaric acid, tetrahydrophthalic acid, hexahydrophthalic acid, adipic acid, sebacic acid, azelaic acid, trimellitic acid, methylcyclohexene tricarboxylic acid, or pyromellitic acid, dimer acids derived from unsaturated fatty acids, and their anhydrides.

[0018] Among the aforementioned polyols, examples include: ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, etc. Furthermore, the aforementioned polyols can also be polyols containing carboxyl groups (hereinafter also referred to as polyols containing carboxyl groups). Examples of polyols containing carboxyl groups include: dimethylolpropionic acid, dimethylolbutyric acid, and diphenolic acid. Furthermore, the aforementioned polyols can also be modified from caprolactone compounds such as ε-caprolactam.

[0019] Regarding the aforementioned polyisocyanate component (b) that reacts with the aforementioned hydroxyl-containing polyester, examples include: aliphatic isocyanate compounds, alicyclic isocyanate compounds, or aromatic isocyanate compounds. Among the aforementioned aliphatic isocyanate compounds, examples include: hexamethylene diisocyanate, propyltrimethylamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, and phenyl dimethyl diisocyanate. Among the aforementioned alicyclic isocyanate compounds, examples include: isophorone diisocyanate, methylcyclohexane diisocyanate, lysine diisocyanate, and cyclohexane-1,4-diisocyanate. Examples of the aforementioned aromatic isocyanate compounds include: toluene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, tetraalkyldiphenylmethane isocyanate, dialkyldiphenylmethane diisocyanate, 1,3'-epenylphenyl diisocyanate, and 1,4'-epenylphenyl diisocyanate.

[0020] Here, in the hot melt adhesive sheet 10 of this embodiment, the aforementioned polyester urethane resin is a polyester urethane resin having an aromatic polyester backbone. When obtaining the aforementioned hydroxyl-containing polyester, by using phthalic acid, isophthalic acid, terephthalic acid, etc. as the aforementioned polycarboxylic acid, the aforementioned polyester urethane resin can possess the aforementioned aromatic polyester backbone. As described above, since the aforementioned polyester urethane resin exhibits high hydrophobicity if it has an aromatic polyester backbone, the adhesive layer 10b containing such polyester urethane resin has improved hydrophobicity. As a result, the adhesive layer 10b exhibits excellent resistance to hot water, acids, and alcohols.

[0021] Regarding the aforementioned commercially available polyester urethane resins, examples include: the VYLON (registered trademark) UR series manufactured by Toyobo Co., Ltd. Among the VYLON (registered trademark) UR series manufactured by Toyobo Co., Ltd., VYLON (registered trademark) UR-3200 and UR-3210 are recommended for commercial use. In addition, VYLON (registered trademark) UR-3210 is a toluene-free version of VYLON (registered trademark) UR-3200. Therefore, if we want to minimize the amount of volatile organic compounds (VOCs) produced, VYLON (registered trademark) UR-3210 is the better choice among commercially available products.

[0022] The glass transition temperature (Tg) of the aforementioned polyester urethane resin having an aromatic polyester backbone is preferably below 10°C. By giving the aforementioned polyester amino ester resin having an aromatic polyester backbone the structure described above, when it is included in the adhesive layer 10b, the adhesive layer 10b can exhibit good adhesion to the substrate 10a and other adhered materials. Examples of substrates 10a include: PEN (polyethylene naphthalate) film, perfluorocarbon sulfonate resin sheet (film), PPS (polyphenylene sulfide) film, etc. Furthermore, by giving the aforementioned polyester amino ester resin the above-described structure, the toughness of the adhesive layer 10b becomes excellent. Therefore, even when an external force is applied to the adhesive layer 10b, the adhesive layer 10b is not easily damaged.

[0023] The aforementioned glass transition temperature Tg is preferably below 5°C, even more preferably below 0°C, and even more preferably below -2°C. Furthermore, the aforementioned glass transfer temperature is preferably above -30°C, more preferably above -20°C, even more preferably above -10°C, and even more preferably above -5°C. In addition, VYLON (registered trademark) UR-3200 and UR-3210 have an aromatic polyester backbone and a glass transition temperature (Tg) of less than 10°C.

[0024] The glass transition temperature Tg can be determined, for example, using a DSC device. More specifically, the aforementioned glass transition temperature Tg can be determined from the DSC curve obtained when the sample (polyurethane resin) is heated at a rate of 5°C / min while nitrogen is introduced between a temperature 30K lower than or 30K higher than the preset glass transition temperature Tg. The glass transition temperature Tg can be determined according to the method described in JIS K7121:1987 "Method for determination of transition temperature of plastics".

[0025] The aforementioned polyurethane resin (A) may also include polyurethane resins other than the aforementioned polyester polyurethane resin. Regarding polyurethane resins other than the aforementioned polyesterurethane resins, various conventional ones can be used, but as the aforementioned polyol component (a), it is preferable to contain a constituent unit derived from a polyol (a1) with a skeletal carbon number of 8 or more.

[0026] In order to react with the isocyanate-based crosslinking agent (C), the polyurethane resin other than the aforementioned polyester polyurethane resin is preferably a hydroxyl-containing polyurethane resin. Furthermore, the aforementioned hydroxyl-containing polyurethane resin preferably has hydroxyl groups at the end. The hydroxyl value of the aforementioned hydroxyl-containing polyurethane resin is preferably 0.1 mg KOH / g or higher and 20 mg KOH / g or lower, and more preferably 1 mg KOH / g or higher and 15 mg KOH / g or lower.

[0027] In polyurethane resins other than the aforementioned polyester urethane resins, the polyol component (a) preferably contains a general polyol (a2) along with a polyol (a1) having a skeleton with 8 or more carbon atoms. In addition, the term "polyol (a2)" will sometimes be used in general to refer to polyol (a2). In this specification, the term "polyol with a carbon skeleton of 8 or more" (a1) refers to a polyol with 8 or more carbon atoms between hydroxyl groups. It refers to a polyol in which 8 or more carbon atoms between hydroxyl groups can be bonded by heteroatoms, and adjacent carbon atoms can be saturatedly bonded or unsaturatedly bonded to each other. Polyols with a skeleton having 8 or more carbon atoms (a1) are preferably polycarbonate polyols. Furthermore, in polyols (a1) with a skeleton having 8 or more carbon atoms, the number of heteroatoms contained in the portion containing 8 or more carbon atoms is preferably 2 or less. Furthermore, polyols (a1) having a skeleton with 8 or more carbon atoms are preferably those containing residues formed by removing multiple hydrogen atoms from saturated or unsaturated hydrocarbons with 8 or more carbon atoms. Furthermore, polyols (a1) having a skeleton with 8 or more carbon atoms are preferably alkyl groups with 6 or more carbon atoms.

[0028] Examples of polyols (a1) having a skeleton with 8 or more carbon atoms include polyester polyols formed by polycondensation of monomers containing dicarboxylic acids (such as sebacic acid (10 carbon atoms), azelaic acid (9 carbon atoms), isophthalic acid (8 carbon atoms), terephthalic acid (8 carbon atoms) etc.) and diols (such as 1,9-nonanediol (9 carbon atoms), 1,4-dihydroxymethylcyclohexane (8 carbon atoms) etc.).

[0029] Furthermore, examples of polyols (a1) having a skeleton with 8 or more carbon atoms include poly(1,4-cyclohexanedimethyl carbonate) diol (8 carbon atoms), polyoctamethylene carbonate diol (8 carbon atoms), polynonamethylene carbonate diol (9 carbon atoms), polydemethyl carbonate diol (10 carbon atoms), and random / block copolymers containing monomers of these types.

[0030] Furthermore, examples of polyols (a1) with a skeleton having 8 or more carbon atoms include polyols derived from dimer acids. The aforementioned dimer acid is a 36-carbon dicarboxylic acid obtained by dimerizing 18-carbon unsaturated fatty acids such as oleic acid or linoleic acid, which are derived from plant fatty acids. The representative structure of the aforementioned dimer acid is represented by the following formula (1). The aforementioned dimer acids may also include trimer acids. Trimeric acids are 54-carbon tricarboxylic acids obtained by trimerizing the aforementioned 18-carbon unsaturated fatty acids. They are also generated as byproducts during the production of dimer acids. Commercially available dimer acids usually contain trimer acids.

[0031]

[0032] Dimer diols, which are polyols derived from dimer acids, are 36-carbon polyols obtained by reducing the carboxyl group of the aforementioned dimer acid to a hydroxyl group. This polyol may or may not have unsaturated bonds in its molecule. Specific examples of such dimer polyols include dimer diols, etc. The same applies to trimer triols, which are polyols obtained by reducing the carboxyl group of a trimer acid to a hydroxyl group. Commercially available dimer diols typically contain trimer triols. Therefore, polyols, dimer polyols, and dimer diols derived from dimer acids may also include trimer triols.

[0033] Furthermore, examples of polyols (a1) with a skeleton having 8 or more carbon atoms include polyolefin polyols. Polyolefin polyols are polymers formed by polymerizing one or more polyolefins having multiple hydroxyl groups. Specific examples of such polyolefin polyols include: polyethylene butadiene glycol, polybutadiene glycol, and hydrogenated polybutadiene glycol. Because these carbon chains aggregate with each other, they are polyols with extremely long carbon chains.

[0034] The adhesive layer 10b of the hot melt adhesive sheet 10 is made of a polyurethane resin (specifically, a polyurethane resin other than the aforementioned polyester polyurethane resin) containing a polyol (a1) having a carbon number of 8 or more derived from the skeleton as described above as the polyurethane resin (A). Compared with those that do not have a polyol (a1) having a carbon number of 8 or more derived from the skeleton, the hydrophobicity of the adhesive layer 10b can be improved. As a result, this adhesive layer 10b exhibits excellent resistance to hot water, acids, and alcohols.

[0035] The aforementioned polyol (a2) can be any polyol known in the synthesis of polyurethane resins. Specific examples of the aforementioned polyols (a2) include: polyester polyols, polyether polyols, polycarbonate polyols, and other polyols.

[0036] For example, polyester polyols can be formed by polycondensation of aliphatic dicarboxylic acids (e.g., succinic acid, adipic acid, glutaric acid, etc.) with low molecular weight diols (e.g., ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexamethylenediol, neopentyl glycol, etc.). Polyester polyols as described above can also be copolymerized with dicarboxylic acids or diols having 8 or more carbon atoms.

[0037] Specific examples of such polyester polyols include: poly(ethylene adipate) diol, poly(butyl adipate) diol, poly(hexamethylene adipate) diol, poly(neoptiate adipate) diol, poly(ethyl / butyl adipate) diol, poly(neoptiate / hexyl adipate) diol, poly(3-methylpentane adipate) diol, poly(butyl isophthalate) diol, polycaprolactone diol, poly(3-methylpentanolide) diol, etc. Polyester polyols have better heat resistance than polyether polyols. Therefore, polyester polyols are more advantageous than polyether polyols in terms of making the heat resistance of the resulting adhesive layer 10b excellent.

[0038] Specific examples of polyether polyols include: polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random / block copolymers of these. Polyether polyols exhibit better hydrolysis resistance than polyester polyols. Therefore, polyether polyols are more advantageous than polyester polyols in terms of making the resulting adhesive layer 10b have excellent hydrolysis resistance.

[0039] Specific examples of polycarbonate polyols include: polytetramethylene carbonate diol, polypentamethylene carbonate diol, polypentamethylene carbonate diol, polyhexamethylene carbonate diol, and random / block copolymers of these. It is also possible to copolymerize polycarbonate polyols as described above with diols having 8 or more carbon atoms. By using various polycarbonate diols as described above as polycarbonate polyols, polyurethane resins other than the aforementioned polyester urethane resins can be made to have carbonate diol constituent units. Here, polycarbonate polyols exhibit excellent hydrolysis resistance and heat resistance. Therefore, it is beneficial to make the resulting adhesive layer 10b have excellent hydrolysis resistance and heat resistance. Among polycarbonate polyols, polyhexamethylene carbonate is the most suitable from the perspective of cost or ease of material availability.

[0040] Other specific examples of polyols include: acrylic polyols, epoxy polyols, polyether ester polyols, silicate-modified polyols, α,ω-polymethyl methacrylate diol, α,ω-polybutyl methacrylate diol, etc.

[0041] Based on the above description of the aforementioned polyol (a2), from the viewpoint of improving the hot water resistance of the adhesive layer 10b of the resulting hot melt adhesive sheet 10, it is preferable to use a polycarbonate polyol with excellent hydrolysis resistance and heat resistance. Furthermore, from the perspective of cost and ease of obtaining materials, polyhexamethylene carbonate is the preferred material among the aforementioned polycarbonate polyols.

[0042] The number average molecular weight Mn of the aforementioned polyols (a1) and (a2) (quantitatively determined by the terminal functional group method) is not particularly limited, but is preferably 500 to 6000. By ensuring that the average molecular weight Mn of the aforementioned polyols (a1) and (a2) is within the range described above, the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment readily exhibits cohesiveness derived from the carbamate bonds. Therefore, the adhesive of this embodiment has high mechanical properties. Furthermore, if the number average molecular weight Mn of crystalline polyols is too large, whitening may occur in adhesive layer 10b when forming a film-like structure such as adhesive layer 10b. Therefore, when using crystalline polyols (a1) and (a2) alone, it is preferable to use those with an average molecular weight Mn of 3,000 or less. In addition, the aforementioned polyols (a1) and (a2) can be used individually or in combination of two or more.

[0043] When the aforementioned polyol component (a) is set to 100% by mass, the aforementioned polyol (a1) is preferably blended in a proportion of 10% by mass or more and 60% by mass or less. By incorporating the aforementioned polyol (a1) at a ratio of 10% by mass or more, the hot melt adhesive of this embodiment can have sufficient resistance to hot water, acid, and alcohol. Furthermore, by incorporating the aforementioned polyol (a1) at a ratio of 60% by mass or less, as the compatibility between the urethane resin (A) and the epoxy resin (B) becomes better, the resulting hot melt adhesive can achieve excellent adhesion to resin films formed from polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, and perfluorocarbon sulfonic acid resin. In addition, when the aforementioned polyol component (a) is a copolymer of a monomer having a skeleton with 8 or more carbon atoms and a monomer having a skeleton with 7 or fewer carbon atoms, the mass part of the monomer having a skeleton with 8 or more carbon atoms is calculated as the mass part of the aforementioned polyol (a1), and the mass part of the monomer having a skeleton with 7 or fewer carbon atoms is calculated as the mass part of the aforementioned polyol (a2).

[0044] Regarding the aforementioned polyol component (a), in addition to the aforementioned polyols (a1) and (a2), short-chain diols (a3) ​​may also be used as needed. Specific examples of the aforementioned short-chain diols (a3) ​​include: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexamethylenediol, neopentyl glycol, and other aliphatic diols and their low molar adducts of epoxy alkane (the number average molecular weight Mn obtained by the terminal functional group quantification method does not reach 500); 1,4-dihydroxymethylcyclohexane, 2-methyl-1,1-cyclohexanediethanol, and other alicyclic diols and their low molar adducts of epoxy alkane (the number average molecular weight Mn does not reach 500, as above); phenyl dimethyl diol and other aromatic diols and their low molar adducts of epoxy alkane (the number average molecular weight Mn does not reach 500, as above); bisphenol A, thiobisphenol, bisphenol A, and other bisphenols and their low molar adducts of epoxy alkane (the number average molecular weight Mn does not reach 500, as above), etc. Among the aforementioned short-chain diols (a3), ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexamethylenediol, neopentyl glycol, etc. are preferred, and ethylene glycol, 1,3-butanediol, and 1,4-butanediol are particularly preferred. These short-chain diols (a3) ​​can be used alone or in combination of two or more.

[0045] In addition, when generating polyurethane resins other than the aforementioned polyesterurethane resins, the materials used as polyurethane resins other than the aforementioned polyesterurethane resins are the same as those used for the aforementioned short-chain diols (a3), and polyol compounds can be used. Specific examples of the aforementioned polyol compounds include: glycerol, trimethylolethane, trimethylolpropane, neopentyl tertrol, tris(2-hydroxyethyl)triisocyanate, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, etc.

[0046] Alternatively, hydroxyl-containing compounds with carboxyl groups (a4) may be used as needed. The aforementioned hydroxyl-containing compounds with carboxyl groups (a4) typically have two or more hydroxyl groups in one molecule. Furthermore, the aforementioned hydroxyl-containing compound (a4) with a carboxyl group usually has two or more hydroxyl groups in one molecule. Therefore, when it reacts with a polyisocyanate component (b) having two or more isocyanate groups in one molecule, polyurethane resin can be obtained.

[0047] Regarding the aforementioned hydroxyl-containing compounds with carboxyl groups (a4), examples include: dimethylolpropionic acid, dimethylolbutyric acid, low molar adducts of such alkyl epoxides (number average molecular weight Mn not exceeding 500), or low molar adducts of γ-caprolactone (number average molecular weight Mn not exceeding 500), hemiesters derived from acid anhydrides and glycerol, and compounds derived by free radical reactions of monomers containing hydroxyl and unsaturated groups with monomers containing carboxyl and unsaturated groups. Of these various compounds, dimethylolpropionic acid or dimethylolbutyric acid is preferred, and dimethylolpropionic acid is even more preferred. These compounds can be used alone or in combination of two or more. Here, the aforementioned number average molecular weight Mn refers to the value determined by the terminal functional group quantitative method. Furthermore, the above-mentioned compounds are examples of preferred compounds in this invention. Therefore, the aforementioned hydroxyl-containing compounds with carboxyl groups (a4) used in this invention are not limited to the various compounds mentioned above. Therefore, in addition to the various compounds mentioned above, any hydroxyl-containing compounds with carboxyl groups that are currently available on the market and can be easily obtained from the market (a4) can be used in this invention.

[0048] With regard to the aforementioned polyisocyanate component (b), conventional polyisocyanate components used in the manufacture of polyurethane resins may be used. Specific examples of the aforementioned polyisocyanate component (b) include: toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, mixtures thereof, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis(phenylene isocyanate) (MDI), and crude or polymeric MDI, durylene diisocyanate. Aromatic diisocyanates such as diisocyanate, phenyl diisocyanate (XDI), 1,5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, and dibenzyl 4,4-diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,10-dedecimethylene diisocyanate; alicyclic diisocyanates such as 1,4-cyclohexyl diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, and hydrogenated XDI; and polyurethane prepolymers obtained by reacting these diisocyanates with low molecular weight polyols to form isocyanates at the ends.

[0049] Among these polyisocyanate components (b), from the viewpoint that an adhesive layer 10b of a heat-resistant hot melt adhesive sheet 10 can be obtained industrially stably and at low cost, it is preferable to use aromatic isocyanates, and more preferably toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, mixtures thereof, 4,4'-methylene bis(phenyl isocyanate) (MDI) and crude or polymeric MDI. By using aromatic isocyanate as the aforementioned polyisocyanate component (b), polyurethane resins other than the aforementioned polyester urethane resin can possess aromatic diisocyanate constituent units. These polyisocyanate components (b) can be used alone or in combination of two or more.

[0050] (Manufacturing method of polyurethane resin (A)) Regarding the manufacturing method of polyurethane resin (A), the manufacturing method of polyester urethane resin will be explained first, followed by the manufacturing method of other polyurethane resins.

[0051] Polyester urethane resin can be manufactured by reacting a hydroxyl-containing polyester with a polyisocyanate component (b). The reaction between the aforementioned hydroxyl-containing polyester and the aforementioned polyisocyanate component (b) can be carried out by conventional methods. In addition, as explained above, in the hot melt adhesive sheet 10 of this embodiment, the polyester urethane resin has an aromatic polyester backbone. To make the aforementioned polyester urethane resin have an aromatic polyester backbone, when obtaining the aforementioned hydroxyl-containing polyester, phthalic acid, isophthalic acid, terephthalic acid, etc. can be used as the aforementioned polycarboxylic acid.

[0052] Polyurethane resins other than polyesterurethane resins can be manufactured using conventional polyurethane manufacturing methods. The following describes a method for manufacturing urethane resins other than polyester urethane resins using polyols (a1) having a skeleton with 8 or more carbon atoms. In addition, when polyols (a1) with a carbon number of 8 or more are not used, polyurethane resins other than polyesterurethane resins can also be manufactured in the same manner as described below. First, in the presence or absence of an organic solvent that does not contain active hydrogen in the molecule, a reaction composition containing the aforementioned polyol (a1) having a skeleton with 8 or more carbon atoms, the aforementioned polyol (a2), the aforementioned polyisocyanate component (b), and a short-chain diol (a3) ​​used as a chain extension agent as needed, is reacted to obtain a polyurethane resin other than a polyesterurethane resin. Furthermore, when obtaining polyurethane resins other than polyesterurethane resins, the aforementioned hydroxyl-containing compounds with carboxyl groups (a4) may also be used as needed. The aforementioned reaction components are generally blends that form an isocyanate group to hydroxyl group equivalent ratio of 0.8 to 1.25. Furthermore, the reaction can be carried out by a one-shot method or a multi-stage method, generally at 20 to 150°C, preferably at 60 to 110°C.

[0053] The average molecular weight (Mw) of the polyurethane resin other than the polyesterurethane resin obtained above is preferably 1,000 or more and 100,000 or less. By ensuring that the mass average molecular weight Mw is within the above-mentioned range, the hot melt adhesive containing the polyurethane resin (A) can more effectively exert its properties such as adhesion to the substrate, hot water resistance, acid resistance, and alcohol resistance. In addition, the mass average molecular weight Mw of polyurethane resins other than the aforementioned polyester urethane resins refers to the value measured by gel permeation chromatography (GPC). The mass average molecular weight (Mw) of polyurethane resins other than the aforementioned polyesterurethane resins can be determined, for example, using the following apparatus and conditions. Measuring apparatus and measuring conditions: • Equipment / Installation Device: Product Name "HLC-8020" (Manufactured by Tosoh Corporation) • Tube column: Product names "TSKgel G2000HXL", "G3000HXL", "G4000GXL" (manufactured by Tosoh Corporation) Solvent: THF • Flow rate: 1.0 ml / min • Sample concentration: 2g / L • Injection volume: 100μL • Temperature: 40℃ • Detector: Model "RI-8020" (manufactured by Tosoh Corporation) • Standard reference material: TSK standard polystyrene (manufactured by Tosoh Corporation)

[0054] In this embodiment, a catalyst may be used as needed in the synthesis of the aforementioned polyester urethane resin and other polyurethane resins. Examples of catalysts mentioned above include: dibutyltin laurate, dioctyltin laurate, stannous octoate, zinc octanoate, tetrabutyl titanate, etc., which are salts of metals and organic or inorganic acids, organometallic derivatives, organic amines such as triethylamine, and diazabicycloundecene catalysts. The aforementioned catalyst promotes the synthesis reaction of the aforementioned polyester urethane resin and other polyurethane resins. On the other hand, if the aforementioned catalyst is used in excess, there is a concern that it may trigger a decomposition reaction that decomposes the aforementioned polyester urethane resin and substances other than polyurethane resins, resulting in a concern that the long-term heat resistance of the obtained hot melt adhesive may deteriorate. Therefore, when using the aforementioned catalyst, it is preferable to use an appropriate amount of the aforementioned catalyst.

[0055] The aforementioned polyester urethane resin and other polyurethane resins can be synthesized without the use of organic solvents, or they can be synthesized using organic solvents. Regarding the aforementioned organic solvents, organic solvents that are inactive relative to the isocyanate group or that are less active relative to the isocyanate group than the reactant can be used. Specific examples of the aforementioned organic solvents include: ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene, xylene, SWAZOLE (trade name, manufactured by COSMO Petroleum Company), and SOLVESSO (trade name, manufactured by EXXON Chemical Company); aliphatic hydrocarbon solvents such as n-hexane; and alcohol solvents such as methanol, ethanol, and isopropanol. Ether solvents such as alkanes and tetrahydrofuran; ester solvents such as ethyl acetate, butyl acetate, and isobutyl acetate; carbonate solvents such as dimethyl carbonate, diethyl carbonate, and ethyl carbonate; glycol ether ester solvents such as ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, and ethyl 3-ethoxypropionate; acetamine solvents such as dimethylformamide and dimethylacetamide; and acetamine solvents such as N-methyl-2-pyrrolidone. From the perspective of improving the solubility of polyurethane resin, or from the perspective of easy volatilization when obtaining hot melt adhesive, toluene, methyl ethyl ketone, and ethyl acetate are preferred.

[0056] (Epoxy Resin (B)) As described above, epoxy resin (B) contains unmodified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less. The aforementioned epoxy equivalent can be 350 g / eq or higher, or 400 g / eq or higher. Furthermore, the aforementioned epoxy equivalent can also be below 1000 g / eq. In addition, unmodified epoxy resin refers to epoxy resin that has not been modified by rubber or other processes. Furthermore, the aforementioned epoxy equivalent refers to the value calculated according to JIS K 7236.

[0057] Examples of unmodified epoxy resins mentioned above include bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AD ​​type epoxy resin. Among these unmodified epoxy resins, bisphenol A type epoxy resin is preferred. For commercially available bisphenol A type epoxy resins with an epoxy equivalent of 300 g / eq to 1500 g / eq, examples include: "JER 1001" (epoxy equivalent of 450 to 500 g / eq), "JER 1002" (epoxy equivalent of 600 to 700 g / eq), "JER 1003" (epoxy equivalent of 670 to 770 g / eq), "JER 1055" (epoxy equivalent of 800 to 900 g / eq), "JER 1004" (epoxy equivalent of 875 to 975 g / eq), and "JER 1004AF" (epoxy equivalent of 875 to 975 g / eq), manufactured by Mitsubishi Chemical Corporation. In addition, the aforementioned unmodified epoxy resins can be used alone or in combination of two or more.

[0058] Epoxy resin (B) may contain rubber-modified epoxy resin in addition to the aforementioned unmodified epoxy resin. In this embodiment, the adhesive layer 10b of the hot melt adhesive sheet 10 contains not only the aforementioned unmodified epoxy resin but also the aforementioned rubber-modified epoxy resin as epoxy resin (B). Therefore, even after long-term immersion in hot water at 95°C, dilute sulfuric acid (pH2) at 95°C, or a water-ethylene glycol mixed solution at 95°C (ethylene glycol mixing ratio of 50 volume%) for 1000 hours while the adhesive layer 10b is coated on the substrate (e.g., PEN film, perfluorocarbon sulfonate resin sheet, PPS film, etc.), the peeling of the adhesive layer 10b from the substrate can be easily suppressed. In addition, the aforementioned rubber-modified epoxy resin refers to a compound that has at least one epoxy group in its molecule and has a structure derived from rubber. The aforementioned rubber-modified epoxy resin can be used alone or in combination with two or more types. Regarding the aforementioned rubber-modified epoxy resins, examples include the reaction products of unmodified epoxy resins and rubber. Regarding the aforementioned unmodified epoxy resins, for example, the aforementioned bisphenol A type epoxy resin, the aforementioned bisphenol F type epoxy resin, and the aforementioned bisphenol AD ​​type epoxy resin can be used.

[0059] By making the epoxy equivalent of the aforementioned unmodified epoxy resin 300 g / eq or more and 1500 g / eq or less, the aforementioned unmodified epoxy resin can be crosslinked at an appropriate crosslinking density in the crosslinking reaction using an isocyanate-based crosslinking agent (C). Therefore, the adhesive layer 10b, which contains the aforementioned unmodified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less, can exert sufficient adhesion to the substrate. Furthermore, if the epoxy equivalent of the aforementioned unmodified epoxy resin exceeds 1500 g / eq, the amount of epoxy groups per unit mass becomes insufficient, thus preventing the aforementioned unmodified epoxy resin from being crosslinked at a sufficient crosslinking density in the crosslinking reaction using the isocyanate-based crosslinking agent (C). Therefore, when the adhesive layer 10b contains the aforementioned unmodified epoxy resin with an epoxy equivalent of more than 1500 g / eq, the adhesive layer 10b cannot obtain sufficient strength and is therefore undesirable. Furthermore, if the epoxy equivalent of the aforementioned unmodified epoxy resin is less than 300 g / eq, the crosslinking density of the aforementioned unmodified epoxy resin becomes too high in the crosslinking reaction using the isocyanate-based crosslinking agent (C) because the amount of epoxy groups per unit mass becomes excessive. Therefore, when the adhesive layer 10b contains an epoxy equivalent of less than 300 g / eq of the aforementioned unmodified epoxy resin, the crosslinking density of the adhesive layer 10b derived from the aforementioned unmodified epoxy resin is too high, making it hard and brittle. As a result, it cannot adequately ensure adhesion to the substrate, and is therefore unsatisfactory.

[0060] Examples of the aforementioned rubbers include: natural rubber, acrylonitrile butadiene rubber (NBR), carboxyl-terminated acrylonitrile butadiene rubber (CTBN), amino-terminated acrylonitrile butadiene rubber (ATBN), styrene butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), ethylene propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber, etc. From the perspective of reactivity with epoxy groups, the aforementioned rubber is preferably end-capped with functional groups such as amine, hydroxyl, or carboxyl groups that can react with epoxy groups.

[0061] From the viewpoint of ease of acquisition and reactivity with epoxy groups, the aforementioned rubber-modified epoxy resins are preferably the reaction product of epoxy resin and acrylonitrile butadiene rubber (NBR) (NBR-modified epoxy resin), the reaction product of epoxy resin and carboxyl-terminated acrylonitrile butadiene rubber (CTBN-modified epoxy resin), and the reaction product of epoxy resin and amino-terminated acrylonitrile butadiene rubber (ATBN-modified epoxy resin). Among these, NBR-modified epoxy resin is particularly preferred. In addition, regarding the aforementioned commercially available NBR modified epoxy resin products, one example is the product manufactured by ADEKA Corporation, under the brand name "ADEKA RESIN EPR-1415-1". Furthermore, the aforementioned method for manufacturing rubber-modified epoxy resin is not particularly limited as long as it allows the epoxy resin to react with the rubber. Various conventional manufacturing methods can be used.

[0062] The physical properties of the aforementioned rubber-modified epoxy resin are not particularly limited. From the viewpoint of operability and adhesion characteristics, it is preferable to have an epoxy equivalent of 150 g / eq or more and 1000 g / eq or less.

[0063] Relative to 100 parts by weight of polyurethane resin (A), epoxy resin (B) may be included in 10 parts by weight or more, or in 20 parts by weight or more, or in 30 parts by weight or more. Furthermore, relative to 100 parts by weight of polyurethane resin (A), epoxy resin (B) can be included in 60 parts by weight or less, or in 50 parts by weight or less. Furthermore, in relation to 100 parts by weight of polyurethane resin (A), the aforementioned unmodified epoxy resin is preferably included in 10 parts by weight or more, and more preferably in 20 parts by weight or more, of epoxy resin (B). Furthermore, relative to 100 parts by weight of polyurethane resin (A), the aforementioned unmodified epoxy resin is preferably included in 40 parts by weight or less, and more preferably in 30 parts by weight or less. Furthermore, in relation to 100 parts by weight of polyurethane resin (A), the aforementioned rubber-modified epoxy resin (B) preferably comprises 5 parts by weight or more, more preferably 10 parts by weight or more, and even more preferably 15 parts by weight or more. Furthermore, compared to 100 parts by weight of polyurethane resin (A), the aforementioned rubber-modified epoxy resin is preferably included in 30 parts by weight or less, and more preferably in 20 parts by weight or less. Furthermore, when the aforementioned epoxy resin (B) includes both the aforementioned unmodified epoxy resin and the aforementioned rubber-modified epoxy resin, the mass ratio of the aforementioned unmodified epoxy resin to the aforementioned rubber-modified epoxy resin may be 1.1 or more, or 1.2 or more, or 1.3 or more. Furthermore, the ratio of the aforementioned unmodified epoxy to the aforementioned rubber-modified epoxy can be 3.0 or less, 2.0 or less, or 1.5 or less.

[0064] (Isocyanate-based crosslinking agent (C)) Regarding the aforementioned isocyanate-based crosslinking agent (C), there are no particular limitations. Conventional materials such as trimer isocyanates, biuret esters, adducts, and polymers with multifunctional isocyanate groups can be used. Examples include: dimers of 2,4-toluene diisocyanate, triphenylmethane triisocyanate, tris(p-isocyanate phenyl)thiophosphate, polyfunctional aromatic isocyanates, polyfunctional aromatic aliphatic isocyanates, polyfunctional aliphatic isocyanates, fatty acid-modified polyfunctional aliphatic isocyanates, end-capped polyfunctional aliphatic isocyanates, and other end-capped polyisocyanates and polyisocyanate prepolymers.

[0065] Among these isocyanate-based crosslinking agents (C), if they are aromatic, diphenylmethane diisocyanate, toluene diisocyanate, and phenyl dimethyl diisocyanate are preferred. If it is an aliphatic system, then hexamethylene diisocyanate and isophorone diisocyanate are preferred modifiers. Furthermore, regarding isocyanate-based crosslinking agents (C), it is preferable that each molecule contains three or more isocyanate groups. Furthermore, regarding the isocyanate-based crosslinking agent (C), it is preferable to use an adduct of the aforementioned polyisocyanate polymer or other compound, or even a urethane prepolymer formed by reacting a low molecular weight polyol with a polyamine to form isocyanate at the molecular end. Of the various isocyanate-based crosslinking agents (C) mentioned above, phenyl diisocyanate is preferred. Regarding the aforementioned commercially available products of phenyl dimethyl diisocyanate, examples include, for instance, the product manufactured by Mitsui Takeda Chemical Co., Ltd. under the trade name "TAKENATE D-110N".

[0066] In the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment, the isocyanate crosslinking agent (C) is preferably contained in 1 part by mass or more, more preferably in 5 parts by mass or more, and even more preferably in 7 parts by mass, relative to 100 parts by mass of the aforementioned polyurethane resin (A). Relative to 100 parts by weight of the aforementioned polyurethane resin (A), the aforementioned isocyanate crosslinking agent (C) is preferably contained in 30 parts by weight or less, more preferably in 20 parts by weight or less, and even more preferably in 15 parts by weight or less. In the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment, by containing the aforementioned isocyanate-based crosslinking agent (C) in the above-mentioned mass ratio, even after long-term immersion in hot water at 95°C, dilute sulfuric acid (pH2) at 95°C, or water-ethylene glycol mixed solution at 95°C (ethylene glycol mixing ratio of 50 volume%) for 1000 hours while the adhesive layer 10b is coated on the substrate (e.g., PEN film, perfluorocarbon sulfonate resin sheet, PPS film, etc.), the adhesive layer 10b can be prevented from peeling off from the aforementioned substrate. That is, the long-term hot water resistance, long-term acid resistance and long-term alcohol resistance of the adhesive layer 10b of the hot melt adhesive sheet 10 become excellent.

[0067] Regarding the reasons why the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment has excellent adhesion to the adhered object and excellent resistance to hot water, acid, and alcohol, the inventors of this case make the following inferences.

[0068] As described above, the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment is formed by a hot melt adhesive, which includes a polyester urethane resin having an aromatic polyester backbone as a polyurethane resin (A), an unmodified epoxy resin (such as bisphenol A type epoxy resin) with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less as an epoxy resin (B), and an isocyanate crosslinking agent (C). Then, in the adhesive layer 10b, the aforementioned polyester urethane resin having an aromatic polyester backbone and the aforementioned unmodified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less are crosslinked by an isocyanate-based crosslinking agent (C). That is, in the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment, the aforementioned polyester urethane resin having an aromatic polyester backbone and the aforementioned unmodified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less are included in the state of being crosslinked by an isocyanate crosslinking agent (C). Here, as explained above, the aforementioned polyester urethane resin with an aromatic polyester backbone exhibits high hydrophobicity. Therefore, by including the aforementioned polyester urethane resin having an aromatic polyester backbone in the adhesive layer 10b, the hydrophobicity of the adhesive layer 10b is improved. It is believed that this improves the hot water resistance, acid resistance, and alcohol resistance of the adhesive layer 10b. Furthermore, if the epoxy equivalent of the unmodified epoxy resin contained in the adhesive layer 10b is more than 300 g / eq and less than 1500 g / eq, then the aforementioned unmodified epoxy resin is cross-linked in the adhesive layer 10b by an isocyanate-based cross-linking agent (C) at an appropriate cross-linking density. It is believed that this enables the adhesive layer 10b to exhibit good adhesion to the substrate. Based on the above, it is believed that the adhesion between the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment and the adhered object becomes excellent, and the resistance to hot water, acid and alcohol also becomes excellent.

[0069] Next, referring to FIG2, we will further explain the case where the substrate bonded to the adhesive layer 10b of the heat-fused adhesive sheet 10 of this embodiment is used as the membrane / electrode assembly (MEA) 20 of a solid polymer fuel cell.

[0070] The aforementioned membrane / electrode assembly (MEA) 20 with the attached material is configured to generate electricity by allowing hydrogen gas to permeate from the negative electrode side to the positive electrode side, thereby causing the oxygen supplied to the positive electrode side to react with the aforementioned hydrogen.

[0071] As shown in Figure 2, in the membrane / electrode assembly (MEA) 20, a positive electrode 202 and a negative electrode 203 are respectively deposited on two opposing surfaces of the solid electrolyte membrane 201. The positive electrode 202 has a positive electrode catalyst layer 202a and a positive electrode gas diffusion layer 202b deposited on the positive electrode catalyst layer 202a. The positive electrode catalyst layer 202a is deposited on one side of the solid electrolyte membrane 201. The negative electrode 203 has a negative electrode catalyst layer 203a and a negative electrode gas diffusion layer 203b deposited on the negative electrode catalyst layer 203a, and the negative electrode catalyst layer 203a is deposited on the other side of the solid electrolyte membrane 201.

[0072] As shown in Figure 2, the positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a are formed with a planar size smaller than that of the solid electrolyte membrane 201, and the positive electrode gas diffusion layer 202b and the negative electrode gas diffusion layer 203b are formed with a planar size smaller than that of the positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a. That is, in the membrane / electrode assembly (MEA), the planar dimensions of the positive electrode 202 and the negative electrode 203 are smaller than the planar dimensions of the solid electrolyte membrane 201. As described above, by making the planar dimension of the positive electrode 202 smaller than the planar dimension of the solid electrolyte membrane 201, on the positive electrode side (one side) of the membrane / electrode assembly (MEA) 20, the solid electrolyte membrane 201 extends further outward than the positive electrode catalyst layer 202a, and a positive electrode side electrolyte membrane exposure region 201a is formed on the outer periphery where the solid electrolyte membrane 201 is exposed on the surface. Furthermore, by making the planar dimension of the negative electrode 203 smaller than the planar dimension of the solid electrolyte membrane 201, on the negative electrode side (the other side) of the membrane / electrode assembly (MEA) 20, the solid electrolyte membrane 201 extends further outward than the negative electrode catalyst layer 203a, and a negative electrode side electrolyte membrane exposure area 201b is formed on the outer periphery where the solid electrolyte membrane 201 is exposed on the surface.

[0073] Furthermore, on the positive electrode side of the membrane / electrode assembly (MEA) 20, the positive electrode catalyst layer 202a extends further outward than the positive electrode gas diffusion layer 202b, thus forming the positive electrode side catalyst layer exposure region 202a1 where the positive electrode catalyst layer 202a is exposed on the surface. The positive electrode side catalyst layer exposure region 202a1 is formed inside the positive electrode side electrolyte membrane exposure region 201a and outside the positive electrode gas diffusion layer 202b. In this embodiment, the positive electrode side electrolyte membrane exposed region 201a is formed in an annular shape around the outer periphery of the membrane / electrode assembly (MEA) 20. The exposed region 202a1 of the catalyst layer on the positive electrode side forms a ring shape that is smaller than the exposed region 201a of the electrolyte membrane on the positive electrode side. That is, on the positive electrode side of the membrane / electrode assembly (MEA), inside the first boundary line L1 between the boundary line of the positive electrode side electrolyte membrane exposed area 201a and the positive electrode side catalyst layer exposed area 202a1, a second boundary line L2 between the positive electrode side catalyst layer exposed area 202a1 and the positive electrode gas diffusion layer 202b is formed.

[0074] On the negative electrode side of the membrane / electrode assembly (MEA) 20, a negative electrode catalyst layer 203a is formed, which extends further outward than the negative electrode gas diffusion layer 203b. The negative electrode side catalyst layer exposure area 203a1 is exposed on the surface of the negative electrode layer 203a. The negative electrode side catalyst layer exposure area 203a1 is formed inside the negative electrode side electrolyte membrane exposure area 201b and outside the negative electrode gas diffusion layer 203b. In this embodiment, the exposed region 201b of the electrolyte membrane on the negative electrode side is formed in an annular shape around the outer periphery of the membrane / electrode assembly (MEA) 20. The exposed area 203a1 of the catalyst layer on the negative electrode side forms a ring that is smaller than the exposed area 201b of the electrolyte membrane on the negative electrode side. That is, on the negative electrode side of the membrane / electrode assembly (MEA) 20, inside the third boundary line L3 of the boundary line between the negative electrode side electrolyte membrane exposed area 201b and the negative electrode side catalyst layer exposed area 203a1, a fourth boundary line L4 of the boundary line between the negative electrode side catalyst layer exposed area 203a1 and the negative electrode gas diffusion layer 203b is formed.

[0075] In the usage state shown in Figure 2, the two hot-melt adhesive sheets 10, which are attached to the positive electrode side of the membrane / electrode assembly (MEA) 20 and the second hot-melt adhesive sheet 10 attached to the negative electrode side of the membrane / electrode assembly (MEA) 20, are used as sub-gasket materials for solid polymer fuel cells.

[0076] The first hot-melt adhesive sheet 10 is annular and, when it overlaps with the membrane / electrode assembly (MEA) 20, has an outer periphery that is further outward than the membrane / electrode assembly (MEA) 20 and an inner periphery that is within the exposed region 202a1 of the positive electrode side catalyst layer and the exposed region 203a1 of the negative electrode side catalyst layer. That is, the empty portion of the first hot-melt bonding sheet 10 has a shape that is one size larger than the positive electrode gas diffusion layer 202b.

[0077] The second hot melt adhesive sheet 10 also has the same shape as the first hot melt adhesive sheet 10.

[0078] In this embodiment, the first hot melt adhesive sheet 10 and the second hot melt adhesive sheet 10 are directly bonded to the outer periphery of the adhesive layer 10b on the outer side of the membrane / electrode assembly (MEA) 20, and are used as the aforementioned secondary gasket material.

[0079] In the first hot-melt adhesive sheet 10, the inner peripheral portion other than the outer peripheral portion that is attached to the second hot-melt adhesive sheet 10 is attached to the outer peripheral portion of the membrane / electrode assembly (MEA) 20, extending from the positive electrode side electrolyte membrane exposed area 201a across the first boundary line L1 to the positive electrode side catalyst layer exposed area 202a1. The second hot melt adhesive piece 10 is bonded in the same way as the first hot melt adhesive piece 10.

[0080] As described above, by attaching (coating) the heat-fused adhesive sheet 10 to the membrane / electrode assembly (MEA) 20, a portion of the positive electrode gas can penetrate the positive electrode side electrolyte membrane to expose region 201a, and a portion of the negative electrode gas can penetrate the negative electrode side electrolyte membrane to expose region 201b, thereby suppressing the performance degradation of the solid polymer fuel cell.

[0081] As explained above, in a solid polymer fuel cell, hydrogen and oxygen react to generate electricity in the membrane / electrode assembly (MEA) 20. Then, as described above, if hydrogen reacts with oxygen, the membrane / electrode junction (MEA) 20 reaches a higher temperature (e.g., 95°C). When the aforementioned solid polymer fuel cell is used as the power source for a vehicle, the central part of the membrane / electrode assembly (MEA) 20 is sufficiently cooled by circulating antifreeze contained in the water tank through pipes. However, the aforementioned pipes are generally not arranged to the edge part of the membrane / electrode assembly (MEA) 20, so the edge part of the membrane / electrode assembly (MEA) 20 continues to maintain a high temperature.

[0082] Furthermore, during the circulation of the aforementioned antifreeze, a portion of the antifreeze leaks out from the aforementioned pipeline, and there is a situation where the antifreeze leaking out from the aforementioned pipeline comes into contact with the adhesive layer 10b installed on the edge side of the solid electrolyte membrane 201. Since the aforementioned antifreeze typically contains polyethylene glycol and water as liquid components, in such cases, the adhesive layer 10b becomes a state of contact with polyethylene glycol and water at high temperatures.

[0083] Furthermore, in the electricity-generating reaction described above, since hydrogen ions (H+) move within the membrane / electrode junction (MEA) 20, the MEA 20 exhibits a strong acidity of approximately 0.1 to 0.5 M, equivalent to dilute sulfuric acid. In this case, the adhesive layer 10b installed on the edge side of the solid electrolyte membrane 201 is exposed to strong acid at high temperature.

[0084] In this embodiment of the hot melt adhesive sheet 10, since the adhesive layer 10b is constructed in the manner described above, the long-term hot water resistance, long-term acid resistance, and long-term alcohol resistance of the adhesive layer 10b become excellent. Therefore, when the hot-melt adhesive sheet of this embodiment is used as the secondary gasket material in a solid polymer fuel cell mounted in a car, as described above, even when the adhesive layer 10b is in contact with water and alcohol at a high temperature of 95°C, or when the adhesive layer 10b is exposed to strong acid at a high temperature of 95°C, it can maintain its adhesion to the solid electrolyte membrane 201 for a long time (1000 hours). In addition, the solid electrolyte membrane 201, as described later, is usually formed of a fluorinated resin such as perfluorocarbon sulfonic acid.

[0085] In addition, in the membrane / electrode assembly (MEA) 20, the positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a are generally formed using a catalyst ink composition that includes a catalyst carrier material such as a carbon material that carries the catalyst, a proton-conductive polymer, and a solvent.

[0086] The solid electrolyte membrane 201 of the membrane / electrode junction (MEA) 20 is formed, for example, from a fluoropolymer such as a perfluorocarbon sulfonic acid resin. Regarding the aforementioned perfluorocarbon sulfonic acid resins, examples include: "Nafion" manufactured by DuPont, "Flemion" manufactured by Asahi Kasei Corporation, and "Aciplex" manufactured by Asahi Glass Corporation. Perfluorocarbon sulfonic acid resins are, for example, resins having a polymer structure as shown in formula (1). Regarding m, n, and x in the following formula (1), for example, in the aforementioned "Nafion", it is m 1. n=2, x=5 to 13.5. In the aforementioned "Aciplex", m=0, 1, n=2 to 5, x=1.5 to 14. In the aforementioned "Flemion", m=0, 1, n=1 to 5.

[0087]

[0088] The positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a are layers containing catalyst particles. Catalyst particles contained in the positive electrode catalyst layer 202a can be listed as: platinum. Catalyst particles contained in the negative electrode catalyst layer 203a can be listed as platinum compounds. Regarding the aforementioned platinum compounds, examples include alloys of platinum with at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, and iron.

[0089] The positive electrode gas diffusion layer 202b and the negative electrode gas diffusion layer 203b are composed of a porous conductive substrate. Examples of porous conductive substrates include carbon paper or carbon cloth.

[0090] Furthermore, the hot-melt adhesive sheet 10 of this embodiment can also be used in redox flow batteries. The hot-melt adhesive used in redox flow batteries is designed to suppress electrolyte penetration.

[0091] The matters disclosed in this specification include the following.

[0092] (1) A hot-melt adhesive sheet comprising a substrate and an adhesive layer formed of a hot-melt adhesive and deposited on at least one side of the substrate, wherein, The aforementioned hot melt adhesive contains a crosslinked adhesive composition comprising a crosslinking agent, wherein the aforementioned adhesive composition comprises polyurethane resin, epoxy resin, and isocyanate-based crosslinking agent. The aforementioned polyurethane resin contains a polyester polyurethane resin with an aromatic polyester backbone. The aforementioned epoxy resin contains unmodified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less.

[0093] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has excellent adhesion to the attached object, and also has excellent resistance to hot water, acid, and alcohol.

[0094] (2) The hot melt adhesive sheet as described in (1) above, wherein the aforementioned polyurethane resin further comprises a polyurethane resin having constituent units derived from polyols with a skeleton carbon number of 8 or more.

[0095] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has better adhesion to the attached object, and also better resistance to hot water, acid, and alcohol.

[0096] (3) The hot-melt adhesive sheet as described in (2) above, wherein the aforementioned polyurethane resin having constituent units derived from polyols with a backbone carbon number of 8 or more is a hydroxyl-containing polyurethane resin. The aforementioned hydroxyl-containing polyurethane resin has a hydroxyl value of ≥0.1 mgKOH / g and ≤20 mgKOH / g.

[0097] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has better adhesion to the attached object, and also better resistance to hot water, acid, and alcohol.

[0098] (4) The heat-fused adhesive sheet as described in (2) or (3) above, wherein, The aforementioned polyurethane resin having constituent units derived from polyols with a skeleton carbon number of 8 or more has aromatic diisocyanate as a constituent unit.

[0099] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has better adhesion to the attached object, and also better resistance to hot water, acid, and alcohol.

[0100] (5) The hot melt adhesive sheet as described in any of (2) to (4) above, wherein the mass average molecular weight Mw of the aforementioned polyurethane resin having constituent units derived from polyols with a carbon number of 8 or more in the skeleton is 1,000 or more and 100,000 or less.

[0101] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has better adhesion to the attached object, and also better resistance to hot water, acid, and alcohol.

[0102] (6) The hot melt adhesive sheet as described in any of (1) to (5) above, wherein the glass transition temperature Tg of the aforementioned polyester urethane resin is below 10°C.

[0103] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has better adhesion to the attached object, and also better resistance to hot water, acid, and alcohol.

[0104] (7) The hot melt adhesive sheet as described in any of (1) to (6) above, wherein the aforementioned unmodified epoxy resin is a bisphenol A type epoxy resin.

[0105] Based on this structure, the adhesive layer of the aforementioned hot melt adhesive sheet has better adhesion to the attached object, and also better resistance to hot water, acid, and alcohol.

[0106] (8) The hot-melt adhesive sheet as described in any of (1) to (7) above is used to bond to the solid electrolyte membrane of a solid polymer fuel cell.

[0107] The hot melt adhesive sheet of the present invention is not limited to the embodiments described above. Furthermore, the hot melt adhesive sheet of the present invention is not limited to the effects described above. Various modifications can be made to the hot melt adhesive sheet of the present invention without departing from the spirit of the invention. [Example]

[0108] (Example 1) The following components were mixed in the proportions shown in Table 1 below to obtain the composition for the hot melt adhesive layer of Example 1. • A polyurethane resin having constituent units derived from polyols (a1) with a backbone of 8 or more carbon atoms (hereinafter also referred to as polyurethane resin A1). • Polyurethane resin (trade name "VYLON (registered trademark) UR-3210" manufactured by Toyobo Co., Ltd.; hereinafter also referred to as polyurethane resin A2) • JER1001, manufactured by Mitsubishi Chemical Corporation, is a bisphenol A type epoxy resin (epoxy equivalent of 450 to 500 g / eq; hereinafter also referred to as epoxy resin B1). • Rubber-modified epoxy resin (trade name "ADEKA RESIN EPR-1415-1" manufactured by ADEKA Corporation; hereinafter also referred to as epoxy resin B2) • Isocyanate-based crosslinking agent (C) (Trade name "TAKENATE D-110N" manufactured by Mitsui Takeda Chemical Co., Ltd.) In addition, polyurethane resin A1 is synthesized in the manner described below, and epoxy resin B1 is used after being dissolved in the manner described below.

[0109] Synthesis of polyurethane resin A1 Prepare a reaction vessel equipped with a stirrer, reflux cooling pipe, thermometer, nitrogen inlet pipe, and manhole. While replacing the interior of the reaction vessel with nitrogen, 300.0 g of polyhexamethylene carbonate diol with two terminal hydroxyl groups (DURANOL: T6002, manufactured by Asahi Kasei Chemicals Co., Ltd.), 200.0 g of polycyclohexanediol / hexanediol copolymer carbonate diol (trade name "ETERNACOLLUM-90(3 / 1)", manufactured by Ube Industries Co., Ltd., hydroxyl value = 112.2 mg KOH / g, cyclohexanediol / hexanediol = 3 / 1 molar ratio) and 10.0 g of 1,3-butanediol were added. Next, 207.3g of methyl ethyl ketone (MEK) was added as a solvent, and the mixture was stirred in the system. After the mixture becomes homogeneous within the system, 111.8 g of 4,4'-diphenylmethane diisocyanate (MDI) is added at 50°C, and the mixture is reacted at 80°C to obtain a reaction solution. The viscosity of the reaction solution was adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction was carried out until the absorption at 2,270 cm⁻¹ from the free isocyanate groups, as determined by infrared absorption spectroscopy, disappeared, thus obtaining a resin solution AA1 containing polyurethane resin A1. The resulting resin solution AA1 contains 30% by mass of solids, polyurethane resin A1 with a hydroxyl value of 2.5 mg KOH / g, and 29.7% by mass of polyols (a1) with 8 or more carbon atoms in the skeleton. Furthermore, the mass-average molecular weight of polyurethane resin A1, as determined by GPC, is 72,000.

[0110] [Dissolution of epoxy resin B1] Prepare a reaction vessel equipped with a stirrer, reflux cooling pipe, thermometer, nitrogen inlet pipe, and manhole. The interior of the reaction vessel was replaced with nitrogen gas, and 400.0 g of epoxy resin B1 (JER1001) was added. Meanwhile, 600.0 g of methyl ethyl ketone (MEK) was added as a solvent while stirring. Then, the system is heated to 60°C to completely dissolve epoxy resin B1, resulting in epoxy resin B1 solution BB1 (hereinafter referred to as epoxy resin solution BB1). The resulting epoxy resin solution BB1 has a solid content of 40% by mass.

[0111] In addition, to explain in more detail, the composition system of the hot melt adhesive layer in Example 1 was obtained in the following manner. (1) Mix resin solution AA1 and epoxy resin solution BB1 in the manner that polyurethane resin A1 and epoxy resin B1 are mixed in the following proportions as shown in Table 1 below to obtain a mixed solution. (2) In the mixed solution, polyurethane resin A2 (polyurethane resin), epoxy resin B2 (rubber-modified epoxy resin) and isocyanate crosslinking agent (C) are added in the following proportions as shown in Table 1. (3) In the aforementioned mixed solution, the aforementioned polyurethane resin A2, the aforementioned epoxy resin B2 and the aforementioned isocyanate crosslinking agent (C) are completely dissolved.

[0112] [Table 1]

[0113] (Example 2) Except for the absence of epoxy resin B2 mentioned above, the hot melt adhesive layer composition of Example 2 was obtained by operating in the same manner as in Example 1.

[0114] (Example 3) Except that the product name "JER1003" (epoxy equivalent of 670 to 770 g / eq) manufactured by Mitsubishi Chemical Corporation was used instead of the product name "JER1001" manufactured by Mitsubishi Chemical Corporation as the bisphenol A type epoxy resin, the same procedure as in Example 1 was followed to obtain the composition for the hot melt adhesive layer of Example 3.

[0115] (Example 4) Except for the absence of epoxy resin B2 mentioned above, the same procedure as in Example 3 was followed to obtain the composition for the hot melt adhesive layer of Example 4.

[0116] (Example 5) Except that the product name "JER1004" (epoxy equivalent 875 to 975 g / eq) manufactured by Mitsubishi Chemical Corporation was used instead of the product name "JER1001" manufactured by Mitsubishi Chemical Corporation as the bisphenol A type epoxy resin, the same procedure as in Example 1 was followed to obtain the composition for the hot melt adhesive layer of Example 5.

[0117] (Example 6) Except for the absence of epoxy resin B2 mentioned above, the hot melt adhesive layer composition of Example 6 was obtained by operating in the same manner as in Example 5.

[0118] (Comparative Example 1) Except that the product name "JER1007" (epoxy equivalent 1750 to 2200 g / eq) manufactured by Mitsubishi Chemical Corporation was used instead of the product name "JER1001" manufactured by Mitsubishi Chemical Corporation as the bisphenol A type epoxy resin, the same procedure as in Example 1 was followed to obtain the composition for the hot melt adhesive layer of Comparative Example 1.

[0119] (Comparative Example 2) Except for the absence of epoxy resin B2 mentioned above, the same procedure as in Comparative Example 1 was followed to obtain the hot melt adhesive layer composition of Comparative Example 2.

[0120] (Comparative Example 3) Except that the product name "JER1256" (epoxy equivalent of 7500 to 8500 g / eq) manufactured by Mitsubishi Chemical Corporation was used instead of the product name "JER1001" manufactured by Mitsubishi Chemical Corporation as the bisphenol A type epoxy resin, the same procedure as in Example 1 was followed to obtain the composition for the hot melt adhesive layer of Comparative Example 3.

[0121] (Comparative Example 4) Except for the absence of epoxy resin B2 mentioned above, the same procedure as in Comparative Example 3 was followed to obtain the hot melt adhesive layer composition of Comparative Example 4.

[0122] (Comparative Example 5) Except that the product name "JER157S70" (epoxy equivalent 200 to 220 g / eq) manufactured by Mitsubishi Chemical Corporation, which belongs to the phenolic varnish type epoxy resin, was used instead of the product name "JER1001" manufactured by Mitsubishi Chemical Corporation, which is a bisphenol A type epoxy resin, the same operation as in Example 1 was performed to obtain the composition for the hot melt adhesive layer of Comparative Example 5.

[0123] (Comparative Example 6) Except for the absence of epoxy resin B2 mentioned above, the same procedure as in Comparative Example 5 was followed to obtain the hot melt adhesive layer composition of Comparative Example 6.

[0124] (Comparative Example 7) Except for the absence of any epoxy resin, the hot melt adhesive layer composition of Comparative Example 7 was obtained by operating in the same manner as in Example 1.

[0125] (Comparative Example 8) Without adding the aforementioned epoxy resin B2, the same procedure as in Comparative Example 7 was followed to obtain the hot melt adhesive layer composition of Comparative Example 8.

[0126] [Coating of the composition for hot melt adhesive layer] The hot melt adhesive layer composition of each example was diluted with methyl ethyl ketone (MEK) to a solid content of 30% by mass. In each example, the diluted hot melt adhesive layer was coated onto one side of a PEN film (longitudinal: 210 mm, transverse: 150 mm, thickness: 100 μm, Teonex: Toyobo Film Solutions Inc.), and after coating, it was dried at 100°C for 1 minute and then placed in an oven at 40°C for 48 hours to allow for a curing reaction (crosslinking reaction), thus obtaining a PEN film with a hot melt adhesive layer. The coating is applied in such a way that the thickness of the dried hot melt adhesive layer is 20 μm.

[0127] [The Production of the First Film] Prepare two PEN films with heat-melt adhesive layers for each example, and overlap the two PEN films with heat-melt adhesive layers by pressing the heat-melt adhesive layers against each other. Using a laminator set to 140°C, two PEN films with heat-melt adhesive layers in each example are heat-pressed together to create the first adhesive sheet in each example.

[0128] [The Production of Part 2] In each example, the exposed surface of the heat-melt adhesive layer of the PEN film with the heat-melt adhesive layer is placed against one side of the perfluorocarbon sulfonate resin sheet (tetrafluoroethylene / perfluoro[2-(fluorosulfonylethoxy)propylvinyl ether] copolymer film (manufactured by DuPont, trade name "NAFIONN-115")) (which has the same shape as the film with the heat-melt adhesive layer), thereby overlapping the PEN film with the heat-melt adhesive layer and the perfluorocarbon sulfonate resin sheet. Using a laminator set to 140°C, the PEN film with the heat-melt adhesive layer in each example is heat-pressed onto the perfluorocarbon sulfonate resin sheet to create the second adhesive sheet in each example.

[0129] [Hot water resistance 1] For each example of the first bonding sheet, a test piece with a width of 10 mm and a length of 80 mm was cut from the first bonding sheet of each example. The test piece was immersed in hot water at 95°C for 1000 hours. After cooling to room temperature, the hot water resistance of each test piece was evaluated according to the following criteria. • Excellent: No peeling was confirmed after soaking. • Yes: Although no peeling was confirmed after soaking, some bulging was observed. • Not allowed: If peeling is confirmed after soaking.

[0130] [Acid Resistance 1] For each example of the first adhesive sheet, a test piece with a width of 10 mm and a length of 80 mm was cut from the first adhesive sheet of each example. The test piece was immersed in dilute sulfuric acid at pH 2 at 95°C for 1000 hours. After cooling to room temperature, the acid resistance of each test piece was evaluated according to the following criteria. • Excellent: No peeling was confirmed after soaking. • Yes: Although no peeling was confirmed after soaking, some bulging was observed. • Not allowed: If peeling is confirmed after soaking.

[0131] [Alcohol resistance 1] For each example of the first adhesive sheet, a test piece with a width of 10 mm and a length of 80 mm was cut from the first adhesive sheet of each example. The test piece was immersed in a water-ethylene glycol mixed solution (ethylene glycol mixing ratio of 50 volume%) at 95°C for 1000 hours. After cooling to room temperature, the alcohol resistance of each test piece was evaluated according to the following criteria. • Excellent: No peeling was confirmed after soaking. • Yes: Although no peeling was confirmed after soaking, some bulging was observed. • Not allowed: If peeling is confirmed after soaking.

[0132] [Hot Water Resistance 2] For each example of the second adhesive sheet, a test piece with a width of 10 mm and a length of 80 mm was cut from the second adhesive sheet of each example. The test piece was immersed in hot water at 95°C for 1000 hours. After cooling to room temperature, the hot water resistance of each test piece was evaluated according to the following criteria. • Excellent: No peeling was confirmed after soaking. • Yes: Although no peeling was confirmed after soaking, some bulging was observed. • Not allowed: If peeling is confirmed after soaking.

[0133] For each example of the second adhesive sheet, a test piece with a width of 10 mm and a length of 80 mm was cut from the second adhesive sheet. The test piece was then immersed in dilute sulfuric acid at pH 2 at 95°C for 1000 hours. After cooling to room temperature, the acid resistance of each test piece was evaluated according to the following criteria. • Excellent: No peeling was confirmed after soaking. • Yes: Although no peeling was confirmed after soaking, some bulging was observed. • Not allowed: If peeling is confirmed after soaking.

[0134] [Alcohol resistance 2] For each example of the second adhesive sheet, a test piece with a width of 10 mm and a length of 80 mm was cut from the second adhesive sheet of each example. The test piece was immersed in a water-ethylene glycol mixed solution (ethylene glycol mixing ratio of 50 volume%) at 95°C for 1000 hours. After cooling to room temperature, the alcohol resistance of each test piece was evaluated according to the following criteria. • Excellent: No peeling was confirmed after soaking. • Yes: Although no peeling was confirmed after soaking, some bulging was observed. • Not allowed: If peeling is confirmed after soaking.

[0135] [Initial Sealing Force] For the first adhesive patch (an adhesive patch formed by sandwiching a hot melt adhesive layer between two PEN films) in each case, the initial adhesion was assessed using Autograph. From the first adhesive piece in each example, a test piece with a width of 10 mm and a length of 80 mm was cut out. For this test piece, the adhesive strength was determined using Autograph. Then, those with a bonding strength of 3N / 10mm or higher are rated as excellent, and those with a bonding strength of less than 3N / 10mm are rated as unacceptable.

[0136] The above evaluation results are shown in Table 2 below.

[0137] [Table 2]

[0138] As can be seen from Table 2 above, in each embodiment, the first adhesive sheet and the second adhesive sheet are both rated as excellent in any evaluation item. Furthermore, it was learned that the initial fit assessment results were also excellent in all embodiments. In contrast, it can be seen that in each comparative example, any evaluation item is either yes or no. Furthermore, in Table 2, if we observe the hot water resistance (hot water resistance 1 and hot water resistance 2), acid resistance (acid resistance 1 and 2), and alcohol resistance (alcohol resistance 1 and alcohol resistance 2) of each comparative example, we can see that the evaluation results of comparative examples 1, 3, 5, and 7 are "acceptable," while the evaluation results of comparative examples 2, 4, 6, and 8 are "unacceptable." Then, Comparative Examples 1, 3, 5 and 7 all contain epoxy resin B2 (rubber-modified epoxy resin), while Comparative Examples 2, 4, 6 and 8 do not contain epoxy resin B2 (rubber-modified epoxy resin), which is different from this point of view. Therefore, it can be inferred that Comparative Examples 1, 3, 5 and 7 have improved hot water resistance, acid resistance and alcohol resistance because they contain epoxy resin B2 (rubber-modified epoxy resin).

[0139] 10: Hot melt adhesive sheet 20: Membrane / electrode assembly (MEA) 201: Solid electrolyte membrane 202: Positive electrode 203: Negative electrode 10a: Substrate 10b: Adhesive layer 201a: Exposed area of ​​electrolyte membrane on the positive electrode side 201b: Exposed area of ​​electrolyte membrane on the negative electrode side 202a: Positive Electrode Catalyst Layer 202b: Positive electrode gas diffusion layer 203a: Negative electrode catalyst layer 203b: Negative electrode gas diffusion layer 202a1: Exposed area of ​​catalyst layer on the positive electrode side 203a1: Exposed area of ​​catalyst layer on the negative electrode side L1: First Boundary Line L2: Second Boundary Line L3: Third Boundary Line L4: 4th Boundary Line

Claims

1. A secondary gasket material for a solid polymer fuel cell, comprising a heat-fused adhesive sheet and bonded to the solid electrolyte membrane of the solid polymer fuel cell; wherein, The hot melt adhesive sheet has a substrate and an adhesive layer formed by a hot melt adhesive and deposited on at least one side of the substrate. The hot melt adhesive contains a crosslinked product of an adhesive composition including a crosslinking agent. The adhesive composition contains a polyurethane resin, an epoxy resin and an isocyanate-based crosslinking agent. The polyurethane resin contains a polyester polyurethane resin having an aromatic polyester backbone. The epoxy resin contains a non-modified epoxy resin with an epoxy equivalent of 300 g / eq or more and 1500 g / eq or less.

2. The secondary gasket material for a solid polymer fuel cell as described in claim 1, wherein, The aforementioned polyurethane resin is composed of the aforementioned polyester urethane resin and polyurethane resins other than the aforementioned polyester urethane resin. The aforementioned polyurethane resins other than the aforementioned polyester urethane resin are polyurethane resins having constituent units derived from polyols with a skeleton carbon number of 8 or more.

3. The secondary gasket material for a solid polymer fuel cell as described in claim 2, wherein, The aforementioned polyurethane resin having constituent units derived from polyols with a skeleton carbon number of 8 or more is a hydroxyl-containing polyurethane resin containing hydroxyl groups, wherein the hydroxyl valence of the aforementioned hydroxyl-containing polyurethane resin is 0.1 mg KOH / g or more and 20 mg KOH / g or less.

4. The secondary gasket material for a solid polymer fuel cell as described in claim 2 or 3, wherein, The aforementioned polyurethane resin having constituent units derived from polyols with a skeleton carbon number of 8 or more has aromatic diisocyanate as a constituent unit.

5. The secondary gasket material for a solid polymer fuel cell as described in claim 2 or 3, wherein, The aforementioned polyurethane resin having constituent units derived from polyols with a skeleton carbon number of 8 or more has a mass average molecular weight Mw of 1,000 or more and 100,000 or less.

6. The secondary gasket material for a solid polymer fuel cell as described in any one of claims 1 to 3, wherein, The glass transition temperature (Tg) of the aforementioned polyester urethane resin having an aromatic polyester backbone is below 10°C.

7. The secondary gasket material for a solid polymer fuel cell as described in any one of claims 1 to 3, wherein, The aforementioned unmodified epoxy resin is a bisphenol A type epoxy resin.

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