Hot melt adhesive sheet

Abstract

This hot-melt adhesive sheet is provided with a base material and an adhesive layer laminated on at least one surface of the base material, the adhesive layer being formed from a hot-melt adhesive, the hot-melt adhesive comprising a crosslinked product of an adhesive composition containing a crosslinking agent, the adhesive composition comprising a polyester resin, an epoxy resin, and an isocyanate crosslinking agent, the epoxy resin contains a bisphenol-type epoxy resin and a rubber-modified epoxy resin, and the bisphenol-type epoxy resin has an epoxy equivalent weight of 450 g / eq or more and 1000 g / eq or less.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Japanese Patent Application No. 2023-110117, the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to a hot melt adhesive sheet. BACKGROUND

[0004] Conventionally, a hot melt adhesive sheet provided with an adhesive layer formed of a hot melt adhesive is known.

[0005] In addition, it is known that such a hot melt adhesive sheet is used by being adhered to a solid electrolyte membrane of a solid polymer fuel cell (for example, Patent Document 1 described below).

[0006] As shown in Patent Document 1 described below, the aforementioned solid polymer fuel cell generally has a membrane-electrode assembly (MEA). The aforementioned membrane-electrode assembly (MEA) is configured in such a manner that a positive electrode and a negative electrode are respectively arranged on both sides of a solid electrolyte membrane.

[0007] Here, in the aforementioned solid polymer fuel cell, the aforementioned positive electrode is generally configured in such a manner that a positive electrode gas diffusion layer is arranged on a positive electrode catalyst layer. In the aforementioned solid polymer fuel cell, the aforementioned negative electrode is generally configured in such a manner that a negative electrode gas diffusion layer is arranged on a negative electrode catalyst layer.

[0008] Also, in the aforementioned membrane-electrode assembly (MEA), the aforementioned positive electrode catalyst layer in the aforementioned positive electrode is arranged on one face of the aforementioned solid electrolyte membrane. In the aforementioned membrane-electrode assembly (MEA), the aforementioned negative electrode catalyst layer in the aforementioned negative electrode is arranged on the other face of the aforementioned solid electrolyte membrane.

[0009] In addition, the aforementioned positive electrode catalyst layer and the aforementioned negative electrode catalyst layer are configured in such a manner as to have a smaller planar size than the aforementioned solid electrolyte membrane. The aforementioned positive electrode gas diffusion layer is configured in such a manner as to have a smaller planar size than the aforementioned positive electrode catalyst layer. The aforementioned negative electrode gas diffusion layer is configured in such a manner as to have a smaller planar size than the aforementioned negative electrode catalyst layer.

[0010] Therefore, when the aforementioned membrane-electrode assembly (MEA) is viewed from the one face side, the outer end edge of the one face of the aforementioned solid electrolyte membrane extends further outward than the outer end edge of the aforementioned positive electrode catalyst layer in the aforementioned positive electrode. When the aforementioned membrane-electrode assembly (MEA) is viewed from the other face side, the outer end edge of the other face of the aforementioned solid electrolyte membrane extends further outward than the outer end edge of the aforementioned negative electrode catalyst layer in the aforementioned negative electrode.

[0011] That is, when the membrane / electrode assembly (MEA) is viewed from one side, an exposed surface is formed between the outer edge of one side of the solid electrolyte membrane and the outer edge of the positive electrode catalyst layer. When the MEA is viewed from the other side, another exposed surface is formed between the outer edge of the other side of the solid electrolyte membrane and the outer edge of the negative electrode catalyst layer.

[0012] Furthermore, as described in Patent Document 1 below, the bonding of the aforementioned hot melt adhesive sheet to the aforementioned solid electrolyte membrane is carried out by using two hot melt adhesive sheets to clamp the aforementioned one exposed surface of the aforementioned solid electrolyte membrane and the aforementioned other exposed surface of the aforementioned solid electrolyte membrane.

[0013] More specifically, the adhesive layer of one of the aforementioned hot-melt adhesive sheets is bonded to one of the aforementioned exposed surfaces of the aforementioned solid electrolyte membrane. The adhesive layer of another of the aforementioned hot-melt adhesive sheets is bonded to the other aforementioned exposed surfaces of the aforementioned solid electrolyte membrane.

[0014] Existing technical documents

[0015] Patent documents

[0016] Patent Document 1: International Publication No. 2019 / 216402 Summary of the Invention

[0017] The problem the invention aims to solve

[0018] However, as described above, after bonding the adhesive layer of one of the aforementioned hot melt adhesive sheets to one of the aforementioned exposed surfaces of the aforementioned solid electrolyte membrane, and bonding the adhesive layer of another of the aforementioned hot melt adhesive sheets to the aforementioned other exposed surface of the aforementioned solid electrolyte membrane, sometimes the gap between the outer edge of the aforementioned solid electrolyte membrane and the aforementioned adhesive layer becomes larger.

[0019] In other words, sometimes the adhesive layer of the aforementioned hot melt adhesive sheet cannot be used to fully cover the outer edge of the aforementioned solid electrolyte membrane.

[0020] In addition, after bonding the adhesive layer of one of the aforementioned hot melt adhesive sheets to one of the aforementioned exposed surfaces of the aforementioned solid electrolyte membrane, and bonding the adhesive layer of another of the aforementioned hot melt adhesive sheets to the aforementioned other exposed surface of the aforementioned solid electrolyte membrane, sometimes the thickness of the aforementioned adhesive layer becomes uneven.

[0021] As described above, when the adhesive layer of the aforementioned hot-melt adhesive sheet cannot adequately cover the outer edge of the aforementioned solid electrolyte membrane, and when the thickness of the adhesive layer of the aforementioned hot-melt adhesive sheet becomes uneven, it will lead to a decrease in the power generation efficiency of the aforementioned solid polymer fuel cell, which is therefore not preferred.

[0022] However, it is difficult to say that sufficient research has been conducted on simultaneously addressing the issues of adequately embedding the outer edge of the aforementioned solid electrolyte membrane with the adhesive layer of the aforementioned hot-melt adhesive sheet, and suppressing the unevenness of the thickness of the adhesive layer of the aforementioned hot-melt adhesive sheet.

[0023] The present invention was made to solve the aforementioned problems, and its objective is to provide a hot-melt adhesive sheet that can simultaneously solve the problems of fully embedding the outer edge of the solid electrolyte membrane of the solid polymer fuel cell by means of the adhesive layer after the adhesive layer is bonded to the solid electrolyte membrane, and suppressing the unevenness of the thickness of the adhesive layer.

[0024] Solution for solving the problem

[0025] The hot melt adhesive sheet of the present invention comprises a substrate and an adhesive layer laminated on at least one side of the substrate, the adhesive layer being formed of a hot melt adhesive, the hot melt adhesive comprising a crosslinked adhesive composition containing a crosslinking agent, the adhesive composition comprising a polyester resin, an epoxy resin and an isocyanate-based crosslinking agent, the epoxy resin comprising a bisphenol type epoxy resin and a rubber-modified epoxy resin, the bisphenol type epoxy resin having an epoxy equivalent of 450 g / eq or more and 1000 g / eq or less. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view illustrating the structure of a hot melt adhesive sheet according to one embodiment of the present invention.

[0027] Figure 2 This is a schematic cross-sectional view showing the state in which a hot-melt adhesive sheet according to one embodiment of the present invention is used to install on the solid electrolyte membrane of a solid polymer fuel cell. Detailed Implementation

[0028] Hereinafter, a hot melt adhesive sheet according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] Hereinafter, one embodiment of the present invention will sometimes be referred to simply as this embodiment.

[0030] like Figure 1 As shown, the hot melt adhesive sheet 10 of this embodiment is a hot melt adhesive sheet on which an adhesive layer 10b formed of hot melt adhesive is laminated on one side of a substrate 10a.

[0031] Figure 1 In the hot melt adhesive sheet 10 shown, the adhesive layer 10b is laminated only on one side of the substrate 10a, but the adhesive layer 10b can also be laminated on the other side of the substrate 10a.

[0032] That is, the hot melt adhesive sheet 10 can also be a hot melt adhesive sheet in which an adhesive layer 10b is laminated on both sides of the substrate 10a.

[0033] In the hot melt adhesive sheet 10 of this embodiment, the aforementioned hot melt adhesive includes a crosslinked product of an adhesive composition containing a crosslinking agent.

[0034] In the hot melt adhesive sheet 10 of this embodiment, the aforementioned adhesive composition includes polyester resin, epoxy resin and isocyanate-based crosslinking agent.

[0035] In the hot melt adhesive sheet 10 of this embodiment, the epoxy resin includes bisphenol type epoxy resin and rubber modified epoxy resin.

[0036] In the hot melt adhesive sheet 10 of this embodiment, the aforementioned bisphenol type epoxy resin has an epoxy equivalent of 450 g / eq or more and 1000 g / eq or less.

[0037] Hereinafter, polyester resin will be referred to as polyester resin (A). Epoxy resin will be referred to as epoxy resin (B). Isocyanate-based crosslinking agents will be referred to as isocyanate-based crosslinking agents (C).

[0038] In addition, among polyester resins (A), crystalline polyester resins are referred to as crystalline polyester resins (a1). Among polyester resins (A), non-crystalline polyester resins are referred to as non-crystalline polyester resins (a2).

[0039] Furthermore, in epoxy resin (B), bisphenol type epoxy resin is referred to as bisphenol type epoxy resin (b1). In epoxy resin (B), rubber-modified epoxy resin is referred to as rubber-modified epoxy resin (b2).

[0040] The hot melt adhesive sheet 10 of this embodiment is used to bond to the solid electrolyte membrane 201 of a solid polymer fuel cell, for example, as described later.

[0041] Solid polymer fuel cells typically include a membrane / electrode assembly (MEA) 20. The MEA 20 is configured such that a positive electrode 202 and a negative electrode 203 are respectively disposed on opposite sides of a solid electrolyte membrane 201.

[0042] Furthermore, in the membrane / electrode assembly (MEA) 20, the positive electrode 202 is configured such that a positive electrode gas diffusion layer 202b is disposed on the positive electrode catalyst layer 202a. In the membrane / electrode assembly (MEA) 20, the negative electrode 203 is configured such that a negative electrode gas diffusion layer 203b is disposed on the negative electrode catalyst layer 203a.

[0043] That is, in the membrane / electrode assembly (MEA) 20, a positive electrode 202 is formed by sequentially distributing a positive electrode catalyst layer 202a and a positive electrode gas diffusion layer 202b on one side of the solid electrolyte membrane 201. In the membrane / electrode assembly (MEA) 20, a negative electrode 203 is formed by sequentially distributing a negative electrode catalyst layer 203a and a negative electrode gas diffusion layer 203b on the other side of the solid electrolyte membrane 201.

[0044] Furthermore, when the membrane / electrode assembly (MEA) 20 is viewed from one side, the outer edge of one side of the solid electrolyte membrane 201 extends further outward than the outer edge of the positive electrode catalyst layer 202a. Similarly, when the MEA 20 is viewed from one side, the outer edge of the positive electrode catalyst layer 202a extends further outward than the outer edge of the positive electrode gas diffusion layer 202b.

[0045] Furthermore, when the membrane / electrode assembly (MEA) 20 is viewed from the other side, the outer edge of the other side of the solid electrolyte membrane 201 extends further outward than the outer edge of the negative electrode catalyst layer 203a. Similarly, when the membrane / electrode assembly (MEA) 20 is viewed from the other side, the outer edge of the negative electrode catalyst layer 203a extends further outward than the outer edge of the negative electrode gas diffusion layer 203b.

[0046] That is, on the outer edge side of one side of the solid electrolyte membrane 201, a first exposed surface (the positive electrode side electrolyte membrane exposed area 201a, described later) is formed between the outer edge of one side of the solid electrolyte membrane 201 and the outer edge of the positive electrode catalyst layer 202a. On the outer edge side of the positive electrode catalyst layer 202a, a second exposed surface (the positive electrode side catalyst layer exposed area 202a1, described later) is formed between the outer edge of the positive electrode catalyst layer 202a and the positive electrode gas diffusion layer 202b.

[0047] Furthermore, on the outer edge side of the other side of the solid electrolyte membrane 201, a third exposed surface (the exposed region 201b of the negative electrode side electrolyte membrane described later) is formed between the outer edge of the other side of the solid electrolyte membrane 201 and the outer edge of the negative electrode catalyst layer 203a. A fourth exposed surface (the exposed region 203a1 of the negative electrode side catalyst layer described later) is formed between the outer edge of the negative electrode catalyst layer 203a and the negative electrode gas diffusion layer 203b.

[0048] In the membrane / electrode assembly (MEA) 20 configured as described above, the bonding of the hot melt adhesive sheet 10 to the solid electrolyte membrane 201 is carried out by using two hot melt adhesive sheets 10 to clamp the solid electrolyte membrane 201 from both sides (i.e., one side and the other side).

[0049] The clamping of the solid electrolyte membrane 201 from both sides using two hot-melt adhesive sheets 10 is carried out in the following manner: the adhesive layer 10b of one hot-melt adhesive sheet 10 is bonded to the aforementioned first exposed surface formed on one side of the solid electrolyte membrane 201 and the aforementioned second exposed surface formed on the positive electrode catalyst layer 202a; and the adhesive layer 10b of the other hot-melt adhesive sheet 10 is bonded to the aforementioned third exposed surface formed on the other side of the solid electrolyte membrane 201 and the aforementioned fourth exposed surface formed on the negative electrode catalyst layer 203a.

[0050] Here, epoxy equivalent (in g / eq) refers to the molecular weight of epoxy resin per functional group (glycidyl group).

[0051] Therefore, the smaller the epoxy equivalent value, the more epoxy groups per structural unit in the epoxy resin. Conversely, the larger the epoxy equivalent value, the fewer epoxy groups per structural unit in the epoxy resin.

[0052] Therefore, the smaller the epoxy equivalent value of the epoxy resin, the higher the crosslinking density of the epoxy resin will be when cured. That is, epoxy resins with a small epoxy equivalent value become cured bodies with high crosslinking density through crosslinking.

[0053] On the other hand, epoxy resins with higher epoxy equivalent values ​​cure at lower crosslinking densities. That is, epoxy resins with high epoxy equivalent values ​​become cured bodies with low crosslinking densities through crosslinking.

[0054] Furthermore, while cured bodies with high crosslinking density exhibit high mechanical strength, this high mechanical strength is accompanied by a corresponding lack of ductility. Conversely, cured bodies with low crosslinking density exhibit high ductility, but this high ductility is accompanied by insufficient mechanical strength.

[0055] Here, in the hot melt adhesive sheet 10 of this embodiment, the hot melt adhesive used to form the adhesive layer 10b includes a bisphenol type epoxy resin having a suitable epoxy equivalent of 450 g / eq or more and 1000 g / eq or less. Therefore, when used by heating the adhesive layer 10b, the bisphenol type epoxy resin can be crosslinked in the adhesive layer 10b at a suitable crosslinking density.

[0056] Therefore, when the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment is heated, it can exhibit a good balance between moderate mechanical strength and moderate ductility.

[0057] That is, the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment can exhibit appropriate toughness when heated and used.

[0058] In addition, the aforementioned hot melt adhesive contains not only the bisphenol-type epoxy resin as described above, but also the aforementioned polyester resin.

[0059] Moreover, the aforementioned polyester resin has a high elastic modulus, and due to its high elastic modulus, it has excellent resilience.

[0060] Therefore, when the adhesive layer 10b formed by the aforementioned hot melt adhesive is heated and used, in addition to the toughness of the aforementioned bisphenol type epoxy resin, it can also exhibit the resilience of the aforementioned polyester resin.

[0061] Furthermore, by including a rubber-modified epoxy resin as the aforementioned epoxy resin in the hot melt adhesive, the adhesive layer 10b formed by the aforementioned hot melt adhesive can exhibit moderate rubber elasticity when heated and used.

[0062] By exhibiting the various characteristics described above, the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment can sufficiently suppress the formation of gaps between the adhesive layer 10b of one hot melt adhesive sheet 10 and the outer edge of the solid electrolyte membrane 201, and between the adhesive layer 10b of another hot melt adhesive sheet 10 and the outer edge of the solid electrolyte membrane 201, as explained above.

[0063] That is, the outer edge of the solid electrolyte membrane 201 can be fully embedded by the adhesive layer 10b of one hot melt adhesive sheet 10 and the adhesive layer 10b of another hot melt adhesive sheet 10.

[0064] Furthermore, by giving the adhesive layer 10b of the hot melt adhesive sheet 10 the aforementioned characteristics, particularly resilience and rubber elasticity, when using it to bond one adhesive layer 10b of the hot melt adhesive sheet 10 to the aforementioned first exposed surface of the solid electrolyte membrane 201 and to bond the adhesive layer 10b of the other hot melt adhesive sheet 10 to the aforementioned third exposed surface of the solid electrolyte membrane 201, it is possible to suppress the unevenness of the thickness of the adhesive layer 10b of one hot melt adhesive sheet 10 and the adhesive layer 10b of the other hot melt adhesive sheet 10.

[0065] (Polyester Resin (A))

[0066] As the aforementioned polyester resin (A), a polyester resin formed by dehydration condensation of a polycarboxylic acid and a polyol can be used.

[0067] Various known polyester resins can be used as the aforementioned polyester resin (A).

[0068] The aforementioned polyester resin (A) may be an unmodified polyester resin or a modified polyester resin.

[0069] The unmodified polyester resin refers to a polyester resin whose structure has not been modified by the modifying components. The aforementioned modified polyester resin refers to a polyurethane resin whose structure has been modified by the modifying components.

[0070] The aforementioned modified polyester resin can be a urethane-modified polyester resin in which an isocyanate component is used as a modifying element to modify part of the structure, or an organosilicon-modified polyester resin in which an organosilicon component is used as a modifying element to modify part of the structure.

[0071] The aforementioned urethane-modified polyester resin can be obtained, for example, by dehydrating and condensing the aforementioned polycarboxylic acid with the aforementioned polyol to obtain a polyester resin, and then reacting the terminal hydroxyl groups of the polyester resin with an isocyanate component.

[0072] Alternatively, the aforementioned urethane-modified polyester resin can also be obtained by simultaneously reacting the aforementioned polycarboxylic acid, the aforementioned polyol, and the aforementioned isocyanate components.

[0073] Commercially available products of the aforementioned urethane-modified polyester resins include, for example, the products manufactured by TOYOBO under the trade name "Vylon (registered trademark) UR-3210" and "Vylon (registered trademark) UR-4410".

[0074] The aforementioned organosilicon-modified polyester resin can be obtained, for example, by reacting the aforementioned polycarboxylic acid, the aforementioned polyol, and a modified organosilicon component having reactive functional groups at one or both ends.

[0075] The aforementioned reactive functional groups in the modified organosilicon components include, for example, hydroxyl, carboxyl, and epoxy groups.

[0076] The aforementioned polyester resin (A) can be a crystalline polyester resin (a1) or a non-crystalline polyester resin (a2).

[0077] That is, the aforementioned unmodified polyester resin and the aforementioned modified polyester resin can be crystalline polyester resin (a1) or non-crystalline polyester resin (a2).

[0078] It should be noted that crystalline polyester resin (a1) refers to the polyester resin that, in the aforementioned unmodified polyester resin and the aforementioned modified polyester resin, shows at least one of the peaks from crystallization and the peaks from crystallization melting when measured using a differential scanning calorimeter (DSC).

[0079] In addition, the aforementioned non-crystalline polyester resin (a2) refers to the polyester resin in which neither the aforementioned unmodified polyester resin nor the aforementioned modified polyurethane resin is displayed in the determination using the aforementioned differential scanning calorimeter (DSC).

[0080] Therefore, when it is necessary to determine whether the aforementioned polyester resin (A) is a crystalline polyester resin (a1) or an amorphous polyester resin (a2), it can be determined by using DSC measurement based on whether at least one of the peaks from crystallization and the peaks from crystallization melting is confirmed.

[0081] Commercially available products of the aforementioned crystalline polyester resin (a1) include those with the trade names "GM920" (manufactured by TOYOBO), "GM913" (manufactured by TOYOBO), "GM-350" (manufactured by TOYOBO), "GM-900" (manufactured by TOYOBO), "UE-9400" (manufactured by UNITIKA LTD.), "UE-3400" (manufactured by UNITIKA LTD.), and "UE-3410" (manufactured by UNITIKA LTD.).

[0082] It should be noted that in the adhesive layer 10b of the hot melt adhesive sheet 10, when a portion of the aforementioned epoxy resin (B) is in an unreacted state, when the aforementioned polyester resin (A) is hydrolyzed into short chains with hydroxyl or carboxyl groups at the molecular ends, these chains can react with the unreacted epoxy groups to make the aforementioned polyester resin (A) long chain again.

[0083] Examples of the polycarboxylic acids constituting the aforementioned polyester resin (A) include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and biphenyl dicarboxylic acid; aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-(hydroxyethoxy)benzoic acid; saturated aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, and itaconic acid; unsaturated alicyclic dicarboxylic acids such as tetrahydrophthalic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid and 1,2-cyclohexanedicarboxylic acid; and tricarboxylic acids and tetracarboxylic acids such as trimellitic acid, pyromellitic acid, and pyromellitic tetracarboxylic acid.

[0084] Examples of aliphatic diols constituting the aforementioned polyester resin (A) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, 3-methyl-1,5-pentanediol, and 2-butyl-2-ethyl-1,3-propanediol; diethylene glycol, triethylene glycol, etc. Oligomeric alkylene glycols such as propylene glycol; alicyclic glycols such as 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, and 1,4-cyclohexanediethanol; polyalkylene ether glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; triols such as trimethylolethane, trimethylolpropane, glycerol, and pentaerythritol; ethylene oxide adducts or propylene oxide adducts of bisphenol A, and ethylene oxide adducts or propylene oxide adducts of hydrogenated bisphenol A, etc.

[0085] The aforementioned polyester resin (A) preferably comprises a crystalline polyester resin (a1) exhibiting a softening point of 120°C or higher.

[0086] The softening point of crystalline polyester resin (a1) refers to the softening point determined by the ring and ball method according to JIS K 7234.

[0087] In the hot melt adhesive sheet 10 of this embodiment, the adhesive layer 10b contains a crystalline polyester resin (a1) having the softening point described above, which can further suppress the softening of the adhesive layer 10b in a high temperature (e.g., 95°C) environment.

[0088] Therefore, after the adhesive layer 10b is bonded to the aforementioned first exposed surface and the aforementioned third exposed surface of the solid electrolyte membrane 201, it can fully embed the outer edge of the solid electrolyte membrane 201, suppress uneven thickness, and has excellent resistance to hot water, acid and alcohol.

[0089] For example, when the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment is used to coat the solid electrolyte membrane of a solid polymer fuel cell, which is the adherend, the adhesive layer 10b can maintain sufficient adhesion to the solid electrolyte membrane 201 even when it comes into contact with water and alcohols such as polyethylene glycol contained in antifreeze at a high temperature such as 95°C, or is exposed to high acidity.

[0090] It should be noted that, as a commercially available product of crystalline polyester resin (a1) with a softening point of 120°C or higher, one example is the product "GM-913" manufactured by TOYOBO.

[0091] The softening point of crystalline polyester resin (a1) can be below 140℃, below 135℃, or below 130℃.

[0092] In addition, the crystalline polyester resin (a1) preferably has a glass transition temperature Tg below -65°C.

[0093] By having a glass transition temperature Tg as described above, the crystalline polyester resin (a1) can exhibit a fully rubbery state at high temperatures (e.g., 95°C).

[0094] Therefore, in the hot melt adhesive sheet 10 of this embodiment, since the adhesive layer 10b contains a crystalline polyester resin (a1) having the glass transition temperature Tg as described above, the adhesive layer 10b can also exhibit a sufficient rubber state at high temperature.

[0095] Therefore, after the adhesive layer 10b is bonded to the aforementioned first exposed surface and the aforementioned third exposed surface of the solid electrolyte membrane 201, it can fully embed the outer edge of the solid electrolyte membrane 201, suppress uneven thickness, and has excellent resistance to hot water, acid and alcohol.

[0096] It should be noted that, as a commercially available product of a crystalline polyester resin (a1) with a glass transition temperature (Tg) below -65°C, the aforementioned product name "GM-913" (manufactured by TOYOBO) can be cited.

[0097] The glass transition temperature Tg of crystalline polyester resin (a1) can be determined, for example, using differential scanning calorimetry (DSC).

[0098] More specifically, the glass transition temperature of the aforementioned sample can be determined from the DSC curve obtained when nitrogen is passed through the sample (crystalline polyester resin (a1)) and the temperature is increased from a temperature 30 K or more below the predicted glass transition temperature Tg at a rate of 5 °C / min to a temperature 30 K or more above the predicted glass transition temperature Tg.

[0099] It should be noted that the glass transition temperature Tg can be determined by using the method described in JIS K7121:1987 "Method for determination of transition temperature of plastics" to determine the intermediate glass transition temperature.

[0100] The glass transition temperature (Tg) of crystalline polyester resin (a1) can be above -90℃, above -80℃, or above -75℃.

[0101] In terms of exhibiting excellent resistance to hot water, acid and alcohol, the polyester resin (A) preferably contains 50% by mass or more of crystalline polyester resin (a1), more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more.

[0102] Furthermore, in order to particularly suit the excellent performance of hot water resistance, acid resistance and alcohol resistance, the polyester resin (A) is particularly preferably entirely composed of crystalline polyester resin (a1). That is, the polyester resin (A) is particularly preferably composed of 100% by mass of crystalline polyester resin (a1).

[0103] The number average molecular weight Mn of the crystalline polyester resin (a1) is preferably 30,000 or more, more preferably 31,000 or more, further preferably 32,000 or more, particularly preferably 33,000 or more, and most preferably 34,000 or more.

[0104] The number average molecular weight Mn of the crystalline polyester resin (a1) is preferably 40,000 or less, more preferably 39,000 or less, even more preferably 38,000 or less, particularly preferably 37,000 or less, and most preferably 36,000 or less.

[0105] In the hot melt adhesive sheet 10 of this embodiment, the adhesive layer 10b is made of a crystalline polyester resin (a1) containing a number-average molecular weight Mn as described above. After the adhesive layer 10b is bonded to the first exposed surface and the third exposed surface of the solid electrolyte membrane 201, it can fully embed the outer edge of the solid electrolyte membrane 201, suppress uneven thickness, and has excellent hot water resistance, acid resistance and alcohol resistance.

[0106] The number-average molecular weight Mn of crystalline polyester resin (a1) can be determined by gel permeation chromatography (GPC).

[0107] The number-average molecular weight Mn of crystalline polyester resin (a1) can be determined, for example, using the following apparatus and conditions.

[0108] Measurement device and measurement conditions

[0109] • Equipment / device: Trade name "HLC-8020" (manufactured by Tosoh Corporation)

[0110] • Pillar: Product names "TSKgel G2000HXL", "TSKgel G3000HXL", "TSKgel G4000HXL" (all manufactured by Tosoh Corporation)

[0111] Solvent: THF

[0112] • Flow rate: 1.0 mL / min

[0113] • Sample concentration: 2 g / L

[0114] Injection volume: 100μL

[0115] Temperature: 40℃

[0116] • Detector: Model "RI-8020" (manufactured by Tosoh Corporation)

[0117] • Standard reference material: TSK standard polystyrene (manufactured by Tosoh Corporation)

[0118] The crystalline polyester resin (a1) preferably has a melt viscosity of 2,000 dPa·s or more at 200°C, more preferably has a melt viscosity of 3,000 dPa·s or more, even more preferably has a melt viscosity of 4,000 dPa·s or more, particularly preferably has a melt viscosity of 5,000 dPa·s or more, and most preferably has a melt viscosity of 6,000 dPa·s or more.

[0119] The crystalline polyester resin (a1) preferably has a melt viscosity of less than 10,000 dPa·s at 200°C, more preferably less than 9,000 dPa·s, even more preferably less than 8,000 dPa·s, and particularly preferably less than 7,000 dPa·s.

[0120] In the hot melt adhesive sheet 10 of this embodiment, the adhesive layer 10b contains a crystalline polyester resin (a1) having the melt viscosity described above. After the adhesive layer 10b is bonded to the first exposed surface and the third exposed surface of the solid electrolyte membrane 201, it can fully embed the outer edge of the solid electrolyte membrane 201, suppress uneven thickness, and has excellent resistance to hot water, acid and alcohol.

[0121] The melt viscosity of crystalline polyester resin (a1) can be determined using a micro-mixer (Thermo, trade name "HAAKE MiniLabII") at 200°C for 100 min. -1 The determination was performed under the condition of ×1 min.

[0122] (Epoxy Resin (B))

[0123] As described above, epoxy resin (B) contains bisphenol type epoxy resin (b1) and rubber modified epoxy resin (b2).

[0124] Examples of bisphenol type epoxy resins (b1) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AD ​​type epoxy resin.

[0125] The aforementioned bisphenol type epoxy resin (b1) can be a modified bisphenol type epoxy resin.

[0126] That is, the aforementioned bisphenol type epoxy resin (b1) can be a modified bisphenol A type epoxy resin, a modified bisphenol F type epoxy resin, or a modified bisphenol AD ​​type epoxy resin.

[0127] As described above, the epoxy equivalent of the bisphenol type epoxy resin (b1) is 450 g / eq or more and 1000 g / eq or less.

[0128] The aforementioned epoxy equivalent can be calculated according to JIS K 7236.

[0129] As the aforementioned bisphenol type epoxy resin (b1), the aforementioned bisphenol A type epoxy resin is preferred.

[0130] Commercially available bisphenol A type epoxy resins include, for example, those manufactured by Mitsubishi Chemical Corporation under the trade names "jER 1001", "jER 1002", "jER 1003", "jER 1055", "jER 1004", and "jER 1004AF".

[0131] Compared to 100 parts by weight of polyester resin (A), bisphenol type epoxy resin (b1) may contain 10 or more parts by weight, 15 or more parts by weight, or 20 or more parts by weight.

[0132] Compared to 100 parts by weight of polyester resin (A), bisphenol type epoxy resin (b1) may contain less than 50 parts by weight, less than 40 parts by weight, or less than 30 parts by weight.

[0133] Rubber-modified epoxy resin (b2) is not particularly limited as long as it is a compound with at least one epoxy group in the molecule and a structure derived from rubber, and various known substances can be used.

[0134] The aforementioned rubber-modified epoxy resin (b2) can be used alone or in combination with two or more types.

[0135] As an example of the aforementioned rubber-modified epoxy resin (b2), a reaction product of epoxy resin and rubber can be cited.

[0136] As the aforementioned epoxy resin, for example, a bisphenol type epoxy resin (b1) as described above can be used.

[0137] 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 butadiene rubber (HNBR), ethylene propylene diene monomer (EPDM), acrylate rubber (ACM), butyl rubber (IIR), and butadiene rubber.

[0138] From the viewpoint of reactivity with epoxy groups, the aforementioned rubber preferably has functional groups such as amino, hydroxyl, and carboxyl groups at the end that can react with epoxy groups.

[0139] Considering factors such as ease of acquisition and reactivity with epoxy groups, the aforementioned rubber-modified epoxy resin (b2) is preferably a reaction product of epoxy resin and acrylonitrile butadiene rubber (NBR) (NBR-modified epoxy resin), a reaction product of epoxy resin and carboxyl-terminated acrylonitrile butadiene rubber (CTBN-modified epoxy resin), or a reaction product of epoxy resin and amino-terminated acrylonitrile butadiene rubber (ATBN-modified epoxy resin), with NBR-modified epoxy resin being particularly preferred.

[0140] It should be noted that, as a commercially available product of the aforementioned NBR modified epoxy resin, one example is the product manufactured by ADEKA under the brand name "ADEKA RESIN EPR-1415-1".

[0141] Furthermore, the manufacturing method of the aforementioned rubber-modified epoxy resin (b2) is not particularly limited as long as it is a method that enables the aforementioned epoxy resin to react with the aforementioned rubber, and various known manufacturing methods can be used.

[0142] The physical properties of the aforementioned rubber-modified epoxy resin (b2) are not particularly limited. However, considering factors such as operability and adhesive properties, an epoxy equivalent of 150 g / eq or more and 1000 g / eq or less is preferred.

[0143] In the aforementioned rubber-modified epoxy resin (b2), the aforementioned epoxy equivalent can also be determined according to JIS K 7236.

[0144] The rubber-modified epoxy resin (b2) may contain 3 or more parts by mass, 5 or more parts by mass, or 7 or more parts by mass relative to 100 parts by mass of polyester resin (A).

[0145] The rubber-modified epoxy resin (b2) may contain up to 20 parts by weight, up to 15 parts by weight, or up to 10 parts by weight, relative to 100 parts by weight of polyester resin (A).

[0146] The mass ratio of rubber-modified epoxy resin (b2) to bisphenol-type epoxy resin (b1) can be 20% or more, 25% or more, or 30% or more.

[0147] In addition, the mass ratio of rubber-modified epoxy resin (b2) to bisphenol-type epoxy resin (b1) can be less than 50%, less than 45%, or less than 40%.

[0148] (Isocyanate-based crosslinking agent (C))

[0149] As for the aforementioned isocyanate-based crosslinking agent (C), there are no particular limitations, and conventionally known substances such as isocyanurates, biuret bodies, adducts, polymers, and other substances with multifunctional isocyanate groups can be used.

[0150] Examples of the aforementioned isocyanate-based crosslinking agents (C) include dimers of 2,4-toluene diisocyanate, triphenylmethane triisocyanate, tris(p-isocyanate phenyl)thiophosphite, 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.

[0151] If the isocyanate-based crosslinking agent (C) is an aromatic isocyanate-based crosslinking agent, then diphenylmethane diisocyanate, toluene diisocyanate, or phenylmethylene diisocyanate are preferred.

[0152] If the isocyanate-based crosslinking agent (C) is an aliphatic isocyanate-based crosslinking agent, then it is preferably a modified form such as hexamethylene diisocyanate or isophorone diisocyanate.

[0153] In addition, the isocyanate-based crosslinking agent (C) preferably contains three or more isocyanate groups in one molecule.

[0154] Furthermore, as an isocyanate-based crosslinking agent (C), polymers of the aforementioned polyisocyanates or adducts of the polymers with other compounds, as well as urethane prepolymers formed by reacting low molecular weight polyols with polyamines to form isocyanates at the molecular ends, are also preferred.

[0155] The isocyanate-based crosslinking agent (C) is preferably phthalimide diisocyanate.

[0156] Commercially available products of the aforementioned dimethyl phthalate include, for example, the product manufactured by Mitsui Takeda Chemical Co., Ltd. under the trade name "TAKENATE D-110N".

[0157] As described above, in the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment, the aforementioned isocyanate crosslinking agent (C) may contain 3 or more parts by mass, 5 or more parts by mass, or 7 or more parts by mass relative to 100 parts by mass of polyester resin (A).

[0158] The aforementioned isocyanate-based crosslinking agent (C) may contain 20 parts or less, 15 parts or less, or 12 parts or less, relative to 100 parts by weight of polyester resin (A).

[0159] Next, refer to Figure 2The following description will be further illustrated by taking the case where the object to be bonded to the adhesive layer 10b of the hot melt adhesive sheet 10 of this embodiment is a membrane / electrode assembly (MEA) 20 of a solid polymer fuel cell as an example.

[0160] The membrane / electrode assembly (MEA) 20, which is the aforementioned adhered material, is configured in such a way that hydrogen gas can pass through from the negative electrode side to the positive electrode side and that oxygen supplied to the positive electrode side reacts with the aforementioned hydrogen to generate electricity.

[0161] like Figure 2 As shown, in the membrane / electrode assembly (MEA) 20, a positive electrode 202 and a negative electrode 203 are stacked on opposite sides of the solid electrolyte membrane 201.

[0162] The positive electrode 202 has a positive electrode catalyst layer 202a and a positive electrode gas diffusion layer 202b stacked on the positive electrode catalyst layer 202a. The positive electrode catalyst layer 202a is stacked on one side of the solid electrolyte membrane 201.

[0163] The negative electrode 203 has a negative electrode catalyst layer 203a and a negative electrode gas diffusion layer 203b stacked on the negative electrode catalyst layer 203a. The negative electrode catalyst layer 203a is stacked on the other side of the solid electrolyte membrane 201.

[0164] like Figure 2 As shown, the positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a are formed with planar dimensions smaller than those of the solid electrolyte membrane 201. The positive electrode gas diffusion layer 202b and the negative electrode gas diffusion layer 203b are formed with planar dimensions smaller than those of the positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a.

[0165] 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.

[0166] As described above, the planar dimension of the positive electrode 202 is smaller than the planar dimension of the solid electrolyte membrane 201. As a result, on the positive electrode side (one side) of the membrane / electrode assembly (MEA) 20, a positive electrode side electrolyte membrane exposure region 201a is formed on the outer periphery, in which the solid electrolyte membrane 201 extends outward beyond the positive electrode catalyst layer 202a and the surface of the solid electrolyte membrane 201 is exposed.

[0167] In addition, the planar dimensions of the negative electrode 203 are smaller than those of the solid electrolyte membrane 201, thereby forming a negative electrode side electrolyte membrane exposure region 201b on the outer periphery of the membrane / electrode junction (MEA) 20, where the solid electrolyte membrane 201 extends further outward than the negative electrode catalyst layer 203a and the surface of the solid electrolyte membrane 201 is exposed.

[0168] It should be noted that the positive electrode side electrolyte membrane exposed area 201a is the first exposed surface mentioned above, and the negative electrode side electrolyte membrane exposed area 201b is the third exposed surface mentioned above.

[0169] In addition, a positive electrode catalyst layer 202a1 is formed on the positive electrode side of the membrane / electrode assembly (MEA) 20, which extends outward from the positive electrode gas diffusion layer 202b and exposes the surface of the positive electrode catalyst layer 202a.

[0170] The catalyst layer exposure region 202a1 on the positive electrode side is formed inside the electrolyte membrane exposure region 201a on the positive electrode side and outside the positive electrode gas diffusion layer 202b.

[0171] In this embodiment, the positive electrode side electrolyte membrane exposed region 201a is formed in a ring shape around the outer periphery of the membrane / electrode assembly (MEA) 20.

[0172] The exposed region 202a1 of the catalyst layer on the positive electrode side is formed into a ring shape that is smaller than the exposed region 201a of the electrolyte membrane on the positive electrode side.

[0173] That is, on the positive electrode side of the membrane / electrode assembly (MEA), inside the boundary line L1 between the positive electrode side electrolyte membrane exposed region 201a and the positive electrode side catalyst layer exposed region 202a1, i.e., the first boundary line L1, a second boundary line L2 is formed between the positive electrode side catalyst layer exposed region 202a1 and the positive electrode gas diffusion layer 202b.

[0174] It should be noted that the exposed region 202a1 of the catalyst layer on the positive electrode side is the second exposed surface mentioned above.

[0175] A negative electrode catalyst layer 203a1 is formed on the negative electrode side of the membrane / electrode assembly (MEA) 20, extending outward from the negative electrode gas diffusion layer 203b and exposing the surface of the negative electrode catalyst layer 203a.

[0176] The catalyst layer exposure region 203a1 on the negative electrode side is formed inside the electrolyte membrane exposure region 201b on the negative electrode side and outside the negative electrode gas diffusion layer 203b.

[0177] In this embodiment, the negative electrode side electrolyte membrane exposed region 201b is formed in a ring shape around the outer periphery of the membrane / electrode assembly (MEA) 20.

[0178] The exposed region 203a1 of the catalyst layer on the negative electrode side is formed into a ring shape smaller than the exposed region 201b of the electrolyte membrane on the negative electrode side.

[0179] That is, on the negative electrode side of the membrane / electrode assembly (MEA) 20, a fourth boundary line L4 is formed inside the boundary line L3 between the negative electrode side electrolyte membrane exposed region 201b and the negative electrode side catalyst layer exposed region 203a1.

[0180] It should be noted that the exposed region 203a1 of the catalyst layer on the negative electrode side is the fourth exposed surface mentioned above.

[0181] exist Figure 2 In the indicated usage state, the first hot-melt adhesive sheet 10 bonded to the positive electrode side of the membrane / electrode assembly (MEA) 20 and the second hot-melt adhesive sheet 10 bonded to the negative electrode side of the membrane / electrode assembly (MEA) 20 are used as subgasket materials for solid polymer fuel cells.

[0182] The first hot melt adhesive sheet 10 is annular. The first hot melt adhesive sheet 10 has the following shape: when the first hot melt adhesive sheet 10 is overlapped on the membrane / electrode assembly (MEA) 20, the outer peripheral edge of the first hot melt adhesive sheet 10 is further outward than the membrane / electrode assembly (MEA) 20, and the inner peripheral edge of the first hot melt adhesive sheet 10 is located in the positive electrode side catalyst layer exposed region 202a1 and the negative electrode side catalyst layer exposed region 203a1.

[0183] That is, the hollow portion of the first hot melt adhesive sheet 10 has a shape that is one size larger than the positive electrode gas diffusion layer 202b.

[0184] The second hot melt adhesive sheet 10 also has the same shape as the first hot melt adhesive sheet 10.

[0185] 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 at a position further outward than the membrane / electrode assembly (MEA) 20, and are used as the aforementioned secondary gasket material.

[0186] In the first hot-melt adhesive sheet 10, the inner peripheral portion other than the outer peripheral portion that is bonded to the second hot-melt adhesive sheet 10 is bonded to the outer peripheral portion of the membrane / electrode assembly (MEA) 20, and is bonded to the range from the positive electrode side electrolyte membrane exposed region 201a (first exposed surface) across the first boundary line L1 to the positive electrode side catalyst layer exposed region 202a1 (second exposed surface).

[0187] The second hot melt adhesive sheet 10 is also bonded in the same way as the first hot melt adhesive sheet 10.

[0188] As described above, by bonding (coating) the hot melt adhesive sheet 10 to the membrane / electrode assembly (MEA) 20, a portion of the positive electrode gas can be exposed through the positive electrode side electrolyte membrane in region 201a, and a portion of the negative electrode gas can be exposed through the negative electrode side electrolyte membrane in region 201b, thereby suppressing the performance degradation of the solid polymer fuel cell.

[0189] Here, the hot melt adhesive sheet 10 of this embodiment is configured as described above.

[0190] Therefore, as described above, after the first hot-melt adhesive sheet 10 is bonded to the area from the positive electrode side electrolyte membrane exposed area 201a (first exposed surface) across the first boundary line L1 to the positive electrode side catalyst layer exposed area 202a1 (second exposed surface), and the second hot-melt adhesive sheet 10 is bonded to the area from the negative electrode side electrolyte membrane exposed area 201b (third exposed surface) across the third boundary line L3 to the negative electrode side catalyst layer exposed area 203a1 (fourth exposed surface), the outer edge of the solid electrolyte membrane 201 can be sufficiently embedded by the adhesive layer 10b, and the thickness of the adhesive layer 10b can be prevented from becoming uneven.

[0191] Specifically, even when a load of 7.5 MPa is applied from the outer side (substrate 10a side) of the first hot melt adhesive sheet 10 and the second hot melt adhesive sheet 10 through a metal gasket at 95°C and the first hot melt adhesive sheet 10 and the second hot melt adhesive sheet 10 are held for 500 hours, the outer edge of the solid electrolyte membrane 201 can be sufficiently embedded through the adhesive layer 10b, and the thickness of the adhesive layer 10b can be suppressed from becoming uneven.

[0192] Here, as previously explained, in a solid polymer fuel cell, hydrogen and oxygen react to generate electricity in the membrane / electrode assembly (MEA) 20.

[0193] Furthermore, as mentioned above, when hydrogen reacts with oxygen, the membrane / electrode junction (MEA) 20 reaches a relatively high temperature (e.g., 95°C).

[0194] When the aforementioned solid polymer fuel cell is installed as a power source for a vehicle, the central portion of the membrane / electrode assembly (MEA) 20 is adequately cooled by circulating antifreeze contained in the radiator through pipes. However, the aforementioned pipes are usually not configured to extend to the edge portion of the membrane / electrode assembly (MEA) 20, so the edge portion of the membrane / electrode assembly (MEA) 20 continues to maintain a high temperature.

[0195] In addition, during the circulation of the aforementioned antifreeze, sometimes a portion of the aforementioned antifreeze leaks out from the aforementioned pipeline, and the leaked antifreeze comes into contact with the adhesive layer 10b installed on the edge side of the solid electrolyte membrane 201.

[0196] The aforementioned antifreeze typically contains polyethylene glycol and water as liquid components. Therefore, under such circumstances, the adhesive layer 10b becomes a state of contact with polyethylene glycol and water at high temperatures.

[0197] Furthermore, in the previously described reaction that generates electricity, hydrogen ions (H+) + Material movement occurs within the membrane / electrode junction (MEA) 20, thus the MEA 20 exhibits strong acidity equivalent to approximately 0.1~0.5M dilute sulfuric acid.

[0198] Under such conditions, the adhesive layer 10b installed on the edge side of the solid electrolyte membrane 201 is exposed to strong acidity at high temperature.

[0199] Here, in the hot melt adhesive sheet 10 of this embodiment, by containing a crystalline polyester resin (a1) having the above-mentioned properties in the adhesive layer 10b, the adhesive layer 10b has excellent resistance to hot water, acid and alcohol.

[0200] Therefore, in a solid polymer fuel cell mounted in a car, when the hot melt adhesive sheet 10 configured in this way is used as a secondary gasket material, even if the adhesive layer 10b is in contact with water or alcohol at a high temperature of 95°C, or exposed to strong acid at a high temperature of 95°C, as described above, the adhesion to the solid electrolyte membrane 201 can be maintained for a long time (1000 hours).

[0201] It should be noted that, as described later, the solid electrolyte membrane 201 is typically formed from fluorinated resins such as perfluorocarbon sulfonic acid.

[0202] It should be noted that in the membrane / electrode assembly (MEA) 20, the positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a are typically formed using a catalyst ink composition comprising a catalyst supporting material such as a carbon material carrying the catalyst, a proton-conducting polymer, and a solvent.

[0203] The solid electrolyte membrane 201 of the membrane / electrode assembly (MEA) 20 is formed, for example, from a fluoropolymer such as a perfluorocarbon sulfonate resin.

[0204] Examples of perfluorocarbon sulfonic acid resins mentioned above include "Nafion" manufactured by DuPont, "Flemion" manufactured by Asahi Kasei Corporation, and "Aciplex" manufactured by Asahi Glass Co., Ltd.

[0205] Perfluorocarbon sulfonic acid resins are, for example, resins having the polymer structure shown in the following formula (1).

[0206] Regarding m, n and x in the following formula (1), for example, in the aforementioned “Nafion”, m≥1, n=2, x=5~13.5, in the aforementioned “Aciplex”, m=0, 1, n=2~5, x=1.5~14, and in the aforementioned “Flemion”, m=0, 1, n=1~5.

[0207]

[0208] The positive electrode catalyst layer 202a and the negative electrode catalyst layer 203a are layers containing catalyst particles.

[0209] Platinum can be listed as a catalyst particle contained in the positive electrode catalyst layer 202a.

[0210] Platinum compounds can be listed as catalyst particles contained in the negative electrode catalyst layer 203a.

[0211] As for the aforementioned platinum compounds, alloys of platinum with at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium and iron can be listed.

[0212] The positive electrode gas diffusion layer 202b and the negative electrode gas diffusion layer 203b are composed of a porous conductive substrate.

[0213] Examples of porous conductive substrates include carbon paper and carbon cloth.

[0214] In addition, the hot melt adhesive sheet 10 of this embodiment can also be used in redox flow batteries.

[0215] The hot-melt adhesive sheet used in redox flow batteries is used to suppress electrolyte permeation.

[0216] The matters disclosed in this specification include the following. (1)

[0218] A hot melt adhesive sheet comprising a substrate and an adhesive layer laminated on at least one side of the substrate.

[0219] The adhesive layer is formed of a hot-melt adhesive, which comprises a crosslinked product of an adhesive composition containing a crosslinking agent.

[0220] The adhesive composition comprises polyester resin, epoxy resin, and isocyanate-based crosslinking agent.

[0221] The epoxy resin includes bisphenol-type epoxy resin and rubber-modified epoxy resin.

[0222] The bisphenol type epoxy resin has an epoxy equivalent of 450 g / eq or more and 1000 g / eq or less.

[0223] According to this configuration, after the adhesive layer is bonded to the solid electrolyte membrane of the solid polymer fuel cell, the outer edge of the solid electrolyte membrane can be fully embedded by the adhesive layer, thus suppressing the unevenness of the thickness of the adhesive layer. (2)

[0225] According to the hot melt adhesive sheet described in (1) above, the aforementioned polyester resin comprises a crystalline polyester resin having a softening point of 120°C or higher.

[0226] According to this configuration, the softening of the adhesive layer can be further suppressed in high-temperature environments (e.g., 95°C). Therefore, after the adhesive layer is bonded to the solid electrolyte membrane of the solid polymer fuel cell, the outer edge of the solid electrolyte membrane can be fully embedded by the adhesive layer, further suppressing uneven thickness of the adhesive layer, and exhibiting excellent resistance to hot water, acids, and alcohols. (3)

[0228] According to the hot melt adhesive sheet described in (1) or (2) above, the bisphenol type epoxy resin comprises bisphenol A type epoxy resin.

[0229] According to this configuration, after the adhesive layer is bonded to the solid electrolyte membrane of the solid polymer fuel cell, the outer edge of the solid electrolyte membrane can be fully embedded by the adhesive layer, thereby further suppressing the unevenness of the thickness of the adhesive layer. (4)

[0231] The hot melt adhesive sheet according to any one of (1) to (3) above, wherein the rubber-modified epoxy resin is an NBR-modified epoxy resin.

[0232] According to this configuration, after the adhesive layer is bonded to the solid electrolyte membrane of the solid polymer fuel cell, the outer edge of the solid electrolyte membrane can be fully embedded by the adhesive layer, thereby further suppressing the unevenness of the thickness of the adhesive layer. (5)

[0234] The hot melt adhesive sheet according to any one of (1) to (4) above is used to bond to the solid electrolyte membrane of a solid polymer fuel cell.

[0235] According to this configuration, after the adhesive layer is bonded to the solid electrolyte membrane of the solid polymer fuel cell, the outer edge of the solid electrolyte membrane can be fully embedded by the adhesive layer, thereby further suppressing the unevenness of the thickness of the adhesive layer.

[0236] 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.

[0237] Example

[0238] [Example of dissolving bisphenol type epoxy resin (b1)]

[0239] <Example of dissolving bisphenol type epoxy resin (b1): B1>

[0240] Prepare a reaction vessel equipped with a stirrer, reflux cooling pipe, thermometer, nitrogen inlet pipe, and inspection port.

[0241] The interior of the aforementioned reaction vessel was purged with nitrogen, and 400.0 g of bisphenol A type epoxy resin (epoxy equivalent: 450~500 g / eq, jER1001: manufactured by Mitsubishi Chemical Corporation. Hereinafter referred to as epoxy resin B1) was added. While stirring, 600.0 g of methyl ethyl ketone (MEK) was added as a solvent. The system was then heated to 60°C to completely dissolve epoxy resin B1 in the aforementioned methyl ethyl ketone.

[0242] Thus, a solution of epoxy resin B1, BB1 (hereinafter referred to as epoxy resin solution BB1), is obtained.

[0243] It should be noted that the solid content of the obtained epoxy resin solution BB1 is 40% by mass.

[0244] <Example of solubility of bisphenol type epoxy resin (b1): B2>

[0245] Instead of epoxy resin B1, bisphenol A type epoxy resin (epoxy equivalent: 670~770 g / eq, JER1003: manufactured by Mitsubishi Chemical Co., Ltd., hereinafter referred to as epoxy resin B2) was used. Otherwise, the same procedure as in the above-described dissolution example B1 was followed to obtain a solution of epoxy resin B2, BB2 (hereinafter referred to as epoxy resin solution BB2).

[0246] It should be noted that the solid content of the obtained epoxy resin solution BB2 is 40% by mass.

[0247] <Example of solubility of bisphenol type epoxy resin (b1): B3>

[0248] Instead of epoxy resin B1, bisphenol A type epoxy resin (epoxy equivalent: 875~975 g / eq, JER1004: manufactured by Mitsubishi Chemical Co., Ltd., hereinafter referred to as epoxy resin B3) was used. Otherwise, the same procedure as in the above-described dissolution example B1 was followed to obtain a solution of epoxy resin B3, BB3 (hereinafter referred to as epoxy resin solution BB3).

[0249] It should be noted that the solid content of the obtained epoxy resin solution BB3 is 40% by mass.

[0250] <Example of dissolving bisphenol type epoxy resin (b1): B4>

[0251] Instead of epoxy resin B1, bisphenol A type epoxy resin (epoxy equivalent: 1,750~2,200 g / eq, JER1007: manufactured by Mitsubishi Chemical Co., Ltd., hereinafter referred to as epoxy resin B4) was used. Otherwise, the procedure was the same as in the above-described dissolution example B1 to obtain a solution of epoxy resin B4, BB4 (hereinafter referred to as epoxy resin solution B4).

[0252] <Example of dissolving bisphenol type epoxy resin (b1): B5>

[0253] Instead of epoxy resin B1, a bisphenol A type phenoxy resin (epoxy equivalent: 7,500~8,500 g / eq, JER1256: manufactured by Mitsubishi Chemical Co., Ltd., hereinafter referred to as epoxy resin B5) was used. Otherwise, the procedure was the same as that in the above-described dissolution example B1 to obtain a solution of epoxy resin B5, BB5 (hereinafter referred to as epoxy resin solution B5).

[0254] <Example of dissolving bisphenol type epoxy resin (b1): B6>

[0255] Instead of epoxy resin B1, a bisphenol A phenolic varnish-type epoxy resin (epoxy equivalent: 200~220 g / eq, JER157S70: manufactured by Mitsubishi Chemical Co., Ltd., hereinafter referred to as epoxy resin B6) was used. Otherwise, the procedure was the same as in the above-described dissolution example B1 to obtain a solution of epoxy resin B6, BB6 (hereinafter referred to as epoxy resin solution BB6).

[0256] [Example 1]

[0257] In epoxy resin solution BB1, a first urethane-modified polyester resin (trade name "VYLON (registered trademark) UR-3210" manufactured by TOYOBO), a rubber-modified epoxy resin (b2) (trade name "ADEKA RESIN EPR-1415-1" manufactured by ADEKA), and an isocyanate-based crosslinking agent (C) (trade name "TAKENATE D-110N" manufactured by Mitsui Takeda Chemical Co., Ltd.) were added as polyester resin (A) in the proportions shown in Table 1A below to obtain the composition for hot melt adhesive layer of Example 1.

[0258] It should be noted that the first urethane-modified polyester resin (“UR-3210”) is added to the epoxy resin solution BB1 as described below.

[0259] That is, the process is carried out by dissolving the first urethane-modified polyester resin in a mixed solvent obtained by mixing toluene and methyl ethyl ketone in a mass ratio of toluene:methyl ethyl ketone = 8:2 to prepare a solution (hereinafter referred to as the first urethane-modified polyester resin solution) at a mass percentage of 25%, and then adding the first urethane-modified polyester resin solution to the epoxy resin solution BB1.

[0260] (Example 2)

[0261] The composition for the hot melt adhesive layer of Example 2 was obtained by using epoxy resin solution BB2 instead of epoxy resin solution BB1, otherwise operated in the same manner as in Example 1.

[0262] (Example 3)

[0263] The composition for the hot melt adhesive layer of Example 3 was obtained by using epoxy resin solution BB3 instead of epoxy resin solution BB1, otherwise operated in the same manner as in Example 1.

[0264] (Example 4)

[0265] As the polyester resin (A), a second urethane-modified polyester resin (manufactured by TOYOBO under the trade name "Vylon (registered trademark) UR-4410") was used instead of the aforementioned first urethane-modified polyester resin. Otherwise, the same procedure as in Example 1 was followed to obtain the hot melt adhesive layer composition of Example 4.

[0266] It should be noted that the aforementioned second urethane-modified polyester resin was added to the aforementioned epoxy resin solution BB1 in the same manner as in Example 1, in the state of preparing a solution of the second urethane-modified polyester resin.

[0267] (Example 5)

[0268] The composition for the hot melt adhesive layer of Example 5 was obtained by using epoxy resin solution BB2 instead of epoxy resin solution BB1, and the aforementioned second urethane-modified polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0269] It should be noted that the aforementioned second urethane-modified polyester resin was added to the aforementioned epoxy resin solution BB2 in the same manner as in Example 4.

[0270] (Example 6)

[0271] The composition for the hot melt adhesive layer of Example 6 was obtained by using epoxy resin solution BB3 instead of epoxy resin solution BB1, and the aforementioned second urethane-modified polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0272] It should be noted that the aforementioned second urethane-modified polyester resin was added to the aforementioned epoxy resin solution BB3 in the same manner as in Example 4.

[0273] (Example 7)

[0274] The composition for the hot melt adhesive layer of Example 7 was obtained by using a first crystalline polyester resin (trade name "GM-920" manufactured by TOYOBO) instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0275] It should be noted that the first crystalline polyester resin was added to the epoxy resin solution BB1 in the same manner as in Example 1, in the form of a first crystalline polyester resin solution.

[0276] (Example 8)

[0277] The composition for the hot melt adhesive layer of Example 8 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB2 and replacing the first urethane-modified polyester resin with the first crystalline polyester resin, otherwise operated in the same manner as in Example 1.

[0278] It should be noted that the first crystalline polyester resin was added to the epoxy resin solution BB2 in the same manner as in Example 7.

[0279] (Example 9)

[0280] The composition for the hot melt adhesive layer of Example 9 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB3 and replacing the first urethane-modified polyester resin with the first crystalline polyester resin, otherwise operated in the same manner as in Example 1.

[0281] It should be noted that the first crystalline polyester resin was added to the epoxy resin solution BB3 in the same manner as in Example 7.

[0282] (Example 10)

[0283] The composition for the hot melt adhesive layer of Example 10 was obtained by using a second crystalline polyester resin (trade name "GM-913" manufactured by TOYOBO) instead of the aforementioned first urethane-modified polyester resin, except that the operation was the same as in Example 1.

[0284] It should be noted that the aforementioned second crystalline polyester resin was added to the aforementioned epoxy resin solution BB1 in the same manner as in Example 1, in the form of a solution of the second crystalline polyester resin.

[0285] (Example 11)

[0286] The composition for the hot melt adhesive layer of Example 11 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB2 mentioned above and replacing the urethane-modified polyester resin with the second crystalline polyester resin mentioned above. Otherwise, the operation was the same as in Example 1.

[0287] It should be noted that the aforementioned second crystalline polyester resin was added to the aforementioned epoxy resin solution BB2 in the same manner as in Example 10.

[0288] (Example 12)

[0289] The composition for the hot melt adhesive layer of Example 12 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB3 mentioned above and replacing the urethane-modified polyester resin with the second crystalline polyester resin mentioned above. Otherwise, the operation was the same as in Example 1.

[0290] It should be noted that the aforementioned second crystalline polyester resin was added to the aforementioned epoxy resin solution BB3 in the same manner as in Example 10.

[0291] (Example 13)

[0292] The composition for the hot melt adhesive layer of Example 13 was obtained by using a third crystalline polyester resin (trade name “UE-9400” manufactured by UNITIKA LTD.) instead of the aforementioned first urethane-modified polyester resin, except that the operation was the same as in Example 1.

[0293] It should be noted that the aforementioned third crystalline polyester resin was added to the aforementioned epoxy resin solution BB1 in the same manner as in Example 1, in the form of a solution of the third crystalline polyester resin.

[0294] (Example 14)

[0295] The composition for the hot melt adhesive layer of Example 14 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB2 mentioned above, and replacing the first urethane-modified polyester resin with the third crystalline polyester resin mentioned above. Otherwise, the operation was the same as in Example 1.

[0296] It should be noted that the aforementioned third crystalline polyester resin was added to the aforementioned epoxy resin solution BB2 in the same manner as in Example 13.

[0297] (Example 15)

[0298] The hot melt adhesive layer composition of Example 15 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB3 mentioned above, and replacing the urethane-modified polyester resin with the crystalline polyester resin mentioned above. Otherwise, the operation was the same as in Example 1.

[0299] It should be noted that the aforementioned third crystalline polyester resin was added to the aforementioned epoxy resin solution BB3 in the same manner as in Example 13.

[0300] (Example 16)

[0301] The composition for the hot melt adhesive layer of Example 16 was obtained by using the fourth crystalline polyester resin (trade name "UE-3400" manufactured by UNITIKA LTD.) instead of the aforementioned first urethane-modified polyester resin, except that the operation was the same as in Example 1.

[0302] It should be noted that the aforementioned fourth crystalline polyester resin was added to the aforementioned epoxy resin solution BB1 in the same manner as in Example 1, in the state of preparing a fourth crystalline polyester resin solution.

[0303] (Example 17)

[0304] The composition for the hot melt adhesive layer of Example 17 was obtained by using the aforementioned epoxy resin solution BB2 instead of the aforementioned epoxy resin solution BB1, and the aforementioned fourth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0305] It should be noted that the aforementioned fourth crystalline polyester resin was added to the aforementioned epoxy resin solution BB2 in the same manner as in Example 16.

[0306] (Example 18)

[0307] The composition for the hot melt adhesive layer of Example 18 was obtained by using the aforementioned epoxy resin solution BB3 instead of the aforementioned epoxy resin solution BB1, and the aforementioned fourth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0308] It should be noted that the aforementioned fourth crystalline polyester resin was added to the aforementioned epoxy resin solution BB3 in the same manner as in Example 16.

[0309] (Example 19)

[0310] The composition for the hot melt adhesive layer of Example 19 was obtained by using the fifth crystalline polyester resin (trade name "UE-3410" manufactured by UNITIKA LTD.) instead of the aforementioned first urethane-modified polyester resin, except that the operation was the same as in Example 1.

[0311] It should be noted that the aforementioned fifth crystalline polyester resin was added to the aforementioned epoxy resin solution BB1 in the same manner as in Example 1, in the state of preparing a fifth crystalline polyester resin solution.

[0312] (Example 20)

[0313] The composition for the hot melt adhesive layer of Example 20 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB2 mentioned above, and replacing the urethane-modified polyester resin with the 5th crystalline polyester resin mentioned above. Otherwise, the operation was the same as in Example 1.

[0314] It should be noted that the aforementioned fifth crystalline polyester resin was added to the aforementioned epoxy resin solution BB2 in the same manner as in Example 19.

[0315] (Example 21)

[0316] The hot melt adhesive composition of Example 21 was obtained in the same manner as in Example 1, except that the epoxy resin solution BB3 was used instead of the epoxy resin solution BB1, and the fifth crystalline polyester resin was used instead of the first urethane-modified polyester resin.

[0317] It should be noted that the aforementioned fifth crystalline polyester resin was added to the aforementioned epoxy resin solution BB3 in the same manner as in Example 19.

[0318] [Table 1A]

[0319]

[0320] [Comparative Example 1]

[0321] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 1 was followed to obtain the hot melt adhesive layer composition of Comparative Example 1.

[0322] (Comparative Example 2)

[0323] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 2 was followed to obtain the hot melt adhesive layer composition of Comparative Example 2.

[0324] (Comparative Example 3)

[0325] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 3 was followed to obtain the hot melt adhesive layer composition of Comparative Example 3.

[0326] (Comparative Example 4)

[0327] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 4 was followed to obtain the hot melt adhesive layer composition of Comparative Example 4.

[0328] (Comparative Example 5)

[0329] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 5 was followed to obtain the hot melt adhesive layer composition of Comparative Example 5.

[0330] (Comparative Example 6)

[0331] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 6 was followed to obtain the hot melt adhesive layer composition of Comparative Example 6.

[0332] (Comparative Example 7)

[0333] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 7 was followed to obtain the hot melt adhesive layer composition of Comparative Example 7.

[0334] (Comparative Example 8)

[0335] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 8 was followed to obtain the hot melt adhesive layer composition of Comparative Example 8.

[0336] (Comparative Example 9)

[0337] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 9 was followed to obtain the hot melt adhesive layer composition of Comparative Example 9.

[0338] (Comparative Example 10)

[0339] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 10 was followed to obtain the hot melt adhesive layer composition of Comparative Example 10.

[0340] (Comparative Example 11)

[0341] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 11 was followed to obtain the hot melt adhesive layer composition of Comparative Example 11.

[0342] (Comparative Example 12)

[0343] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 12 was followed to obtain the hot melt adhesive layer composition of Comparative Example 12.

[0344] (Comparative Example 13)

[0345] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 13 was followed to obtain the hot melt adhesive layer composition of Comparative Example 13.

[0346] (Comparative Example 14)

[0347] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 14 was followed to obtain the hot melt adhesive layer composition of Comparative Example 14.

[0348] (Comparative Example 15)

[0349] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 15 was followed to obtain the hot melt adhesive layer composition of Comparative Example 15.

[0350] (Comparative Example 16)

[0351] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 16 was followed to obtain the hot melt adhesive layer composition of Comparative Example 16.

[0352] (Comparative Example 17)

[0353] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 17 was followed to obtain the hot melt adhesive layer composition of Comparative Example 17.

[0354] (Comparative Example 18)

[0355] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 18 was followed to obtain the hot melt adhesive layer composition of Comparative Example 18.

[0356] (Comparative Example 19)

[0357] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 19 was followed to obtain the hot melt adhesive layer composition of Comparative Example 19.

[0358] (Comparative Example 20)

[0359] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 20 was followed to obtain the hot melt adhesive layer composition of Comparative Example 20.

[0360] (Comparative Example 21)

[0361] Except for the absence of the aforementioned rubber-modified epoxy resin (b2), the same procedure as in Example 21 was followed to obtain the hot melt adhesive layer composition of Comparative Example 21.

[0362] The formulations of the compositions for the hot melt adhesive layer of Comparative Examples 1 to 21 are shown in Table 1B below.

[0363] [Table 1B]

[0364]

[0365] (Comparative Example 22)

[0366] The composition for the hot melt adhesive layer of Comparative Example 22 was obtained by replacing the aforementioned epoxy resin solution BB1 with the aforementioned epoxy resin solution BB4, otherwise operated in the same manner as in Example 1.

[0367] (Comparative Example 23)

[0368] The composition for the hot melt adhesive layer of Comparative Example 23 was obtained by replacing the aforementioned epoxy resin solution BB1 with the aforementioned epoxy resin solution BB5, otherwise operated in the same manner as in Example 1.

[0369] (Comparative Example 24)

[0370] The composition for the hot melt adhesive layer of Comparative Example 24 was obtained by using epoxy resin solution BB6 instead of epoxy resin solution BB1, otherwise operated in the same manner as in Example 1.

[0371] (Comparative Example 25)

[0372] The composition for the hot melt adhesive layer of Comparative Example 25 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB4 described above and replacing the polyester resin modified with the second urethane ester modified with the first urethane ester modified with the second ...

[0373] (Comparative Example 26)

[0374] The composition for the hot melt adhesive layer of Comparative Example 26 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB5 mentioned above and replacing the polyester resin modified with the second urethane ester modified with the first urethane ester modified with the second ...

[0375] (Comparative Example 27)

[0376] The composition for the hot melt adhesive layer of Comparative Example 27 was obtained by using the aforementioned epoxy resin solution BB6 instead of the aforementioned epoxy resin solution BB1, and the aforementioned second urethane-modified polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0377] (Comparative Example 28)

[0378] The composition for the hot melt adhesive layer of Comparative Example 28 was obtained by using the aforementioned epoxy resin solution BB4 instead of the aforementioned epoxy resin solution BB1, and the aforementioned first crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0379] (Comparative Example 29)

[0380] The composition for the hot melt adhesive layer of Comparative Example 29 was obtained by using the aforementioned epoxy resin solution BB5 instead of the aforementioned epoxy resin solution BB1, and the aforementioned first crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0381] (Comparative Example 30)

[0382] The composition for the hot melt adhesive layer of Comparative Example 30 was obtained by using the aforementioned epoxy resin solution BB6 instead of the aforementioned epoxy resin solution BB1, and the aforementioned first crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0383] (Comparative Example 31)

[0384] The composition for the hot melt adhesive layer of Comparative Example 31 was obtained by using the aforementioned epoxy resin solution BB4 instead of the aforementioned epoxy resin solution BB1, and the aforementioned second crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0385] (Comparative Example 32)

[0386] The composition for the hot melt adhesive layer of Comparative Example 32 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB5 and replacing the urethane-modified polyester resin with the second crystalline polyester resin, otherwise operated in the same manner as in Example 1.

[0387] (Comparative Example 33)

[0388] The composition for the hot melt adhesive layer of Comparative Example 33 was obtained by using the aforementioned epoxy resin solution BB6 instead of the aforementioned epoxy resin solution BB1, and the aforementioned second crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0389] (Comparative Example 34)

[0390] The composition for the hot melt adhesive layer of Comparative Example 34 was obtained by using the aforementioned epoxy resin solution BB4 instead of the aforementioned epoxy resin solution BB1, and the aforementioned third crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0391] (Comparative Example 35)

[0392] The composition for the hot melt adhesive layer of Comparative Example 35 was obtained by using the aforementioned epoxy resin solution BB5 instead of the aforementioned epoxy resin solution BB1, and the aforementioned third crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0393] (Comparative Example 36)

[0394] The composition for the hot melt adhesive layer of Comparative Example 36 was obtained by using the aforementioned epoxy resin solution BB6 instead of the aforementioned epoxy resin solution BB1, and the aforementioned third crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0395] (Comparative Example 37)

[0396] The composition for the hot melt adhesive layer of Comparative Example 37 was obtained by replacing the epoxy resin solution BB1 with the epoxy resin solution BB4 described above and replacing the urethane-modified polyester resin with the fourth crystalline polyester resin described above. Otherwise, the operation was the same as in Example 1.

[0397] (Comparative Example 38)

[0398] The composition for the hot melt adhesive layer of Comparative Example 38 was obtained by using the aforementioned epoxy resin solution BB5 instead of the aforementioned epoxy resin solution BB1, and the aforementioned fourth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0399] (Comparative Example 39)

[0400] The composition for the hot melt adhesive layer of Comparative Example 39 was obtained by using the aforementioned epoxy resin solution BB6 instead of the aforementioned epoxy resin solution BB1, and the aforementioned fourth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0401] (Comparative Example 40)

[0402] The composition for the hot melt adhesive layer of Comparative Example 40 was obtained by using the aforementioned epoxy resin solution BB4 instead of the aforementioned epoxy resin solution BB1, and the aforementioned fifth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0403] (Comparative Example 41)

[0404] The composition for the hot melt adhesive layer of Comparative Example 41 was obtained by using the aforementioned epoxy resin solution BB5 instead of the aforementioned epoxy resin solution BB1, and the aforementioned fifth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0405] (Comparative Example 42)

[0406] The composition for the hot melt adhesive layer of Comparative Example 42 was obtained by using the aforementioned epoxy resin solution BB6 instead of the aforementioned epoxy resin solution BB1, and the aforementioned sixth crystalline polyester resin instead of the aforementioned first urethane-modified polyester resin, otherwise operated in the same manner as in Example 1.

[0407] The formulations of the compositions for the hot melt adhesive layer of Comparative Examples 22-42 are shown in Table 1C below.

[0408] [Table 1C]

[0409]

[0410] Furthermore, the various physical properties of the various polyester resins (A) (first urethane-modified polyester resin (UR-3210), second urethane-modified polyester resin (UR-4410), first crystalline polyester resin (GM-920), second crystalline polyester resin (GM-913), third crystalline polyester resin (UE-9400), fourth crystalline polyester resin (UE-3400), and fifth crystalline polyester resin (UE-3410)) blended in the hot melt adhesive layer compositions of each example are shown in Table 2 below.

[0411] [Table 2]

[0412]

[0413] [Coating of the composition for hot melt adhesive layer]

[0414] The hot melt adhesive layers of each example and comparative example were diluted with methyl ethyl ketone (MEK) to a solid content of 30% by weight.

[0415] Next, following the steps below, PEN films with a hot melt adhesive layer were obtained for each embodiment and each comparative example.

[0416] (1) The diluted hot melt adhesive layer is coated with the composition onto one side of the PEN film (length: 210mm, width: 150mm, thickness: 100μm, TEONEX: TOYOBO FILM SOLUTIONS LIMITED).

[0417] It should be noted that the aforementioned coating was performed with the dry product of the hot melt adhesive layer composition having a thickness of 20 μm.

[0418] (2) The PEN film coated with the diluted hot melt adhesive layer composition is dried at 100°C for 1 minute to obtain a dried PEN film with the hot melt adhesive layer composition.

[0419] (3) The dried PEN film containing the hot melt adhesive layer is placed in an oven at 40°C for 48 hours to carry out a curing reaction (crosslinking reaction). Thus, a PEN film with a hot melt adhesive layer is obtained.

[0420] (Thickness retention rate of hot melt adhesive layer)

[0421] For the PEN films with hot-melt adhesive layers in each embodiment and the PEN films with hot-melt adhesive layers in each comparative example, the retention rate of the thickness of the hot-melt adhesive layer after being bonded to the solid electrolyte membrane of the solid polymer fuel cell was evaluated.

[0422] It should be noted that in this evaluation, the material used as the adhered object is... Figure 2 The membrane / electrode assembly (MEA) 20 of the solid polymer fuel cell is shown.

[0423] Furthermore, the bonding of the PEN film with the hot melt adhesive layer to the membrane / electrode assembly (MEA) 20, which is the adherend, in each embodiment and comparative example is carried out according to the following steps.

[0424] It should be noted that the description of the structure of the membrane / electrode junction (MEA) 20 will not be repeated.

[0425] Bonding step

[0426] (1) For each embodiment and each comparative example, two PEN films with a hot melt adhesive layer were prepared.

[0427] It should be noted that, in each embodiment and comparative example, the PEN film with the hot melt adhesive layer is annular and has a shape in which, when it overlaps with the membrane / electrode assembly (MEA) 20, the outer peripheral edge is further outward than the membrane / electrode assembly (MEA) 20 and the inner peripheral edge is contained within the positive electrode side catalyst layer exposed region 202a1 and the negative electrode side catalyst layer exposed region 203a1.

[0428] That is, in each embodiment and comparative example, the hollow portion of the PEN film with the hot melt adhesive layer has a shape that is larger than that of the positive electrode gas diffusion layer 202b and the negative electrode gas diffusion layer 203b.

[0429] (2) Make a PEN film with a hot melt adhesive layer abut against the entire area of ​​the electrolyte membrane exposed area 201a on the positive electrode side and a part of the catalyst layer exposed area 202a1 on the positive electrode side.

[0430] In addition, another PEN film with a hot melt adhesive layer is brought into contact with the entire area of ​​the electrolyte membrane exposed on the negative electrode side 201b and a portion of the catalyst layer exposed on the negative electrode side 203a1.

[0431] Thus, a sample with two PEN films with hot melt adhesive layers bonded to the membrane / electrode assembly (MEA) 20 was obtained.

[0432] (3) After exposing the aforementioned sample to an atmosphere of 95°C, a pair of metal gaskets are brought into contact with the central portion of the exposed surface of a PEN film with a hot melt adhesive layer and another PEN film with a hot melt adhesive layer, respectively.

[0433] Then, the sample was exposed to an atmosphere of 95°C and subjected to a load of 7.5 MPa through the aforementioned pair of metal gaskets for 500 hours.

[0434] Thus, one PEN film with a hot melt adhesive layer and another PEN film with a hot melt adhesive layer are hot melt bonded to the membrane / electrode assembly (MEA) 20.

[0435] It should be noted that the retention rate of the hot melt adhesive layer thickness is evaluated according to the following criteria.

[0436] Reference

[0437] Advantage: Based on the thickness of the hot melt adhesive layer (central part) before bonding, the thickness of the hot melt adhesive layer (central part) after bonding becomes more than 80%.

[0438] Not allowed: The thickness of the hot melt adhesive layer (central part) after bonding shall be less than 80% of the thickness of the hot melt adhesive layer before bonding.

[0439] The results of the investigation on the retention rate of the thickness of the hot melt adhesive layer are shown in Table 3 below.

[0440] (Based on the embedding properties of the hot melt adhesive layer)

[0441] The encapsulation properties of the PEN films with hot-melt adhesive layers in each embodiment and the PEN films with hot-melt adhesive layers in each comparative example were investigated after being bonded to the solid electrolyte membrane of a solid polymer fuel cell.

[0442] Regarding the embedding properties based on the hot melt adhesive layer, after bonding two PEN films with hot melt adhesive layers from each embodiment and each comparative example to the membrane / electrode assembly (MEA) 20 according to the above steps, the bonding state of the two PEN films with hot melt adhesive layers was observed using a laser microscope, and thus evaluated.

[0443] It should be noted that the magnification of the laser microscope is set to 400x.

[0444] In addition, the embedding properties based on the hot melt adhesive layer are evaluated according to the following criteria.

[0445] Reference

[0446] Advantage: The distance between the outer edge of the solid electrolyte membrane and the hot melt adhesive layer is less than 200 μm.

[0447] Not allowed: The distance from the outer edge of the solid electrolyte membrane to the hot melt adhesive layer exceeds 200 μm.

[0448] The results of the investigation on the embedding properties of the hot melt adhesive layer are shown in Table 3 below.

[0449] [Table 3]

[0450]

[0451] As shown in Table 3, the thickness retention and embedding properties of the PEN films with hot melt adhesive layers in each embodiment were rated as "excellent".

[0452] In contrast, it can be seen that in the PEN films with hot melt adhesive layers in each comparative example, the thickness retention and embedding properties were both evaluated as "unacceptable".

[0453] Next, as shown below, the compositions for the hot melt adhesive layers of Test Examples 1 to 20 were prepared.

[0454] [Experimental Example 1]

[0455] Using the same formulation as in Example 10, a composition for the hot melt adhesive layer of Test Example 1 was obtained.

[0456] [Experimental Example 2]

[0457] The amount of epoxy resin B1 was changed from 25 parts by weight to 30 parts by weight. Otherwise, the same procedure was followed as in Test Example 1 to obtain the hot melt adhesive layer composition of Test Example 2.

[0458] [Experimental Example 3]

[0459] The amount of epoxy resin B1 was changed from 25 parts by weight to 35 parts by weight. Otherwise, the same procedure was followed as in Test Example 1 to obtain the hot melt adhesive layer composition of Test Example 3.

[0460] [Experimental Example 4]

[0461] Using the same formulation as in Example 11, the composition for the hot melt adhesive layer of Test Example 4 was obtained.

[0462] [Experimental Example 5]

[0463] The amount of epoxy resin B2 was changed from 25 parts by weight to 30 parts by weight. Otherwise, the same procedure was followed as in Test Example 4 to obtain the hot melt adhesive layer composition of Test Example 5.

[0464] [Experimental Example 6]

[0465] The amount of epoxy resin B2 was changed from 25 parts by weight to 35 parts by weight. Otherwise, the same procedure as in Test Example 4 was followed to obtain the hot melt adhesive layer composition of Test Example 6.

[0466] [Experimental Example 7]

[0467] The amount of epoxy resin B1 was changed from 25 parts by weight to 20 parts by weight. Otherwise, the same procedure was followed as in Comparative Example 10 to obtain the hot melt adhesive layer composition of Test Example 7.

[0468] [Experimental Example 8]

[0469] The amount of epoxy resin B2 was changed from 25 parts by weight to 20 parts by weight. Otherwise, the same procedure was followed as in Comparative Example 11 to obtain the hot melt adhesive layer composition of Test Example 8.

[0470] [Experimental Example 9]

[0471] Using the same formulation as Comparative Example 10, the composition for the hot melt adhesive layer of Test Example 9 was obtained.

[0472] [Experimental Example 10]

[0473] Using the same formulation as Comparative Example 11, the composition for the hot melt adhesive layer of Test Example 10 was obtained.

[0474] [Experimental Example 11]

[0475] Except for the absence of epoxy resin B1, the hot melt adhesive layer composition of Test Example 11 was obtained with the same formulation as Test Example 1.

[0476] [Experimental Example 12]

[0477] Using the same formulation as Comparative Example 12, the composition for the hot melt adhesive layer of Test Example 12 was obtained.

[0478] [Experimental Example 13]

[0479] The composition for the hot melt adhesive layer of Example 13 was obtained by using the same formulation as Example 1, except that the sixth crystalline polyester resin (trade name "GM-350" manufactured by TOYOBO) was used instead of the second crystalline polyester resin.

[0480] [Experimental Example 14]

[0481] The composition for the hot melt adhesive layer of Example 14 was obtained by using the same formulation as Example 4 except that the sixth crystalline polyester resin was used instead of the second crystalline polyester resin.

[0482] [Experimental Example 15]

[0483] The composition for the hot melt adhesive layer of Example 15 was obtained by using the same formulation as Example 1, except that the 7th crystalline polyester resin (trade name "GM-900" manufactured by TOYOBO) was used instead of the 2nd crystalline polyester resin.

[0484] [Experimental Example 16]

[0485] The composition for the hot melt adhesive layer of Example 16 was obtained by using the same formulation as Example 4 except that the 7th crystalline polyester resin was used instead of the 2nd crystalline polyester resin.

[0486] [Experimental Example 17]

[0487] Except for changing the mixing amount of isocyanate-based crosslinking agent (C) (TAKENATE D-110N) from 10 parts by mass to 15 parts by mass, the hot melt adhesive layer composition of Test Example 17 was obtained with the same formulation as Test Example 1.

[0488] [Experimental Example 18]

[0489] Except for changing the mixing amount of isocyanate-based crosslinking agent (C) (TAKENATE D-110N) from 10 parts by mass to 15 parts by mass, the hot melt adhesive layer composition of Example 18 was obtained with the same formulation as Example 4.

[0490] [Experimental Example 19]

[0491] Except for changing the mixing amount of isocyanate-based crosslinking agent (C) (TAKENATE D-110N) from 10 parts by mass to 5 parts by mass, the hot melt adhesive layer composition of Test Example 19 was obtained with the same formulation as Test Example 1.

[0492] [Experimental Example 20]

[0493] Except for changing the mixing amount of isocyanate-based crosslinking agent (C) (TAKENATE D-110N) from 10 parts by mass to 5 parts by mass, the hot melt adhesive layer composition of Test Example 20 was obtained with the same formulation as Test Example 4.

[0494] The formulations of the compositions for the hot melt adhesive layers in Examples 1 to 20 are shown in Table 4 below.

[0495] [Table 4]

[0496]

[0497] In addition, the various physical properties of the sixth crystalline polyester (GM-350) and the seventh crystalline polyester resin (GM-900) are shown in Table 5 below.

[0498] [Table 5]

[0499]

[0500] [Coating of the composition for hot melt adhesive layer]

[0501] Except for the use of the hot melt adhesive layer composition in each test example, the PEN film with hot melt adhesive layer in each test example was obtained in the same manner as the PEN film with hot melt adhesive layer in each embodiment and each comparative example.

[0502] [Preparation of the first adhesive sheet]

[0503] Prepare two PEN films with hot melt adhesive layers from each test example, and overlap the two PEN films with hot melt adhesive layers by abutting each other.

[0504] Using a laminator set to 140°C, two PEN films with hot-melt adhesive layers from each test example were bonded together by hot pressing to create the first adhesive sheet for each test example.

[0505] [Preparation of the second adhesive sheet]

[0506] In each test example, the PEN film with the hot melt adhesive layer and the perfluorocarbon sulfonate sheet were overlapped in such a way that the exposed surface of the hot melt adhesive layer of the PEN film with the hot melt adhesive layer was abutted against one side of the perfluorocarbon sulfonate sheet (tetrafluoroethylene / perfluoro[2-(fluorosulfonylethoxy)propyl vinyl ether] copolymer film (manufactured by DuPont, trade name "NAFIONN-115")) (which has the same shape as the film with the hot melt adhesive layer).

[0507] Using a laminator set to 140°C, the PEN film with the hot-melt adhesive layer of each test example was bonded to the perfluorocarbon sulfonate resin sheet by hot pressing to produce the second adhesive sheet of each test example.

[0508] [Hot water resistance 1]

[0509] For the first adhesive sheet of each test example, a test piece with a width of 10 mm and a length of 80 mm was cut from the first adhesive sheet of each test 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.

[0510] • Excellent: No peeling was confirmed after impregnation.

[0511] • Not allowed: If peeling is confirmed after soaking.

[0512] [Acid Resistance 1]

[0513] For the first adhesive sheet of each test example, a test piece measuring 10 mm wide × 80 mm long was cut from the first adhesive sheet of each test example. 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.

[0514] • Excellent: No peeling was confirmed after impregnation.

[0515] • Not allowed: If peeling is confirmed after soaking.

[0516] [Alcohol resistance 1]

[0517] For the first adhesive sheet of each test example, a test piece measuring 10 mm wide × 80 mm long was cut from the first adhesive sheet of each test example. The test piece was immersed in a water-ethylene glycol mixture at 95°C (ethylene glycol mixing ratio of 50% by volume) for 1000 hours. After cooling to room temperature, the alcohol resistance of each test piece was evaluated according to the following criteria.

[0518] • Excellent: No peeling was confirmed after impregnation.

[0519] • Not allowed: If peeling is confirmed after soaking.

[0520] [Hot Water Resistance 2]

[0521] For the second adhesive sheet of each test example, a test piece with a width of 10 mm and a length of 80 mm was cut from the second adhesive sheet of each test 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.

[0522] • Excellent: No peeling was confirmed after impregnation.

[0523] • Not allowed: If peeling is confirmed after soaking.

[0524] [Acid Resistance 2]

[0525] For the second adhesive sheet of each test example, a test piece measuring 10 mm wide × 80 mm long was cut from the second adhesive sheet of each test example. 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.

[0526] • Excellent: No peeling was confirmed after impregnation.

[0527] • Not allowed: If peeling is confirmed after soaking.

[0528] [Alcohol resistance 2]

[0529] For the second adhesive sheet of each test example, a test piece measuring 10 mm wide and 80 mm long was cut from the second adhesive sheet of each test example. The test piece was immersed in a water-ethylene glycol mixture at 95°C (ethylene glycol mixing ratio of 50% by volume) for 1000 hours. After cooling to room temperature, the alcohol resistance of each test piece was evaluated according to the following criteria.

[0530] • Excellent: No peeling was confirmed after impregnation.

[0531] • Not allowed: If peeling is confirmed after soaking.

[0532] The results of evaluating the hot water resistance 1, acid resistance 1, and alcohol resistance 1 of the first adhesive sheet of each test example are shown in Table 5 below, and the results of evaluating the hot water resistance 2, acid resistance 2, and alcohol resistance 2 of the second adhesive sheet of each test example are shown in Table 6 below.

[0533] [Table 6]

[0534]

[0535] As shown in Table 6 above, in Test Examples 1 to 6, all evaluation items for the first adhesive sheet and the second adhesive sheet were "excellent", that is, the result was that no delamination was confirmed.

[0536] In contrast, in Test Examples 7-20, it can be seen that all evaluation items for the first and second adhesive sheets were "unacceptable", that is, the result was confirmed as delamination.

[0537] Explanation of reference numerals in the attached figures

[0538] 10 Hot-melt adhesive sheet, 20 Membrane / electrode assembly (MEA), 201 Solid electrolyte membrane, 202 Positive electrode, 203 Negative electrode.

[0539] 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.

[0540] L1 is the first boundary line, L2 is the second boundary line, L3 is the third boundary line, and L4 is the fourth boundary line.

Claims

1. A hot-melt adhesive sheet comprising a substrate and an adhesive layer laminated on at least one side of the substrate, The adhesive layer is formed of hot melt adhesive. The hot melt adhesive comprises a crosslinked product of an adhesive composition containing a crosslinking agent, the adhesive composition comprising polyester resin, epoxy resin, and isocyanate-based crosslinking agent. The epoxy resin includes bisphenol-type epoxy resin and rubber-modified epoxy resin. The bisphenol type epoxy resin has an epoxy equivalent of 450 g / eq or more and 1000 g / eq or less.

2. The hot-melt adhesive sheet according to claim 1, wherein, The polyester resin comprises a crystalline polyester resin having a softening point of 120°C or higher.

3. The hot-melt adhesive sheet according to claim 1 or 2, wherein, The bisphenol type epoxy resin includes bisphenol A type epoxy resin.

4. The hot-melt adhesive sheet according to claim 1 or 2, wherein, The rubber-modified epoxy resin is an NBR-modified epoxy resin.

5. The hot-melt adhesive sheet according to claim 1 or 2, used to bond to the solid electrolyte membrane of a solid polymer fuel cell.

Images