Fuel cell stack and fuel cell

Abstract

Provided are: a fuel battery stack which can be manufactured in an industrially advantageous manner and which comprises a sealing member having excellent hydrofluoric acid-resistant characteristics; and a fuel battery comprising said fuel battery stack.　The fuel battery stack is formed by laminating a plurality of fuel battery cells each composed of a pair of separators sandwiching a membrane-electrode assembly. The sealing member is provided to the separators. The sealing member is a cured product of a perfluoropolyether compound-containing curable composition.

Description

[Technical Field]

[0001] The present invention relates to a fuel cell stack and a fuel cell including the fuel cell stack. [Background technology]

[0002] Fuel cells are expected to be the next generation of power generation devices due to their high power generation efficiency and extremely low environmental impact. Polymer electrolyte fuel cells (PEFCs) can be made small and lightweight, and have a high power density, so they are attracting attention as an in-vehicle internal combustion engine.

[0003] A fuel cell includes a plurality of stacked fuel cell units, each of which includes an electrode member including a membrane electrode assembly (MEA) and a pair of separators that sandwich the electrode member.

[0004] Fuel gas (such as hydrogen) flows through the first surface of each separator, and oxidant gas (such as air or oxygen) flows through the second surface. The separator has through-holes that run through the separator in the thickness direction, which serve as flow paths for reactant gases. On both thickness-wise sides of the separator, sealing members are arranged in a frame shape around the electrode members and through-holes, and are compressed by fastening forces from both outside in the stacking direction, bringing them into contact with the mating members. This prevents leakage of gas and other fluids from the flow paths, making it possible to stabilize the operation of the fuel cell.

[0005] The membrane electrode assembly (MEA), which is the power generating part of a polymer electrolyte fuel cell, is composed of a fuel electrode (anode), an electrolyte membrane, and an air electrode (cathode). The electrolyte membrane is mainly made of a fluoropolymer with sulfonic acid groups. Therefore, the sealing material must be resistant to the sulfuric acid and hydrofluoric acid that are present in the electrolyte membrane.

[0006] Patent Document 1 discloses a sealing material that is resistant to sulfuric acid and hydrofluoric acid, but there is room for improvement in the resistance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-016813 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an object of the present invention is to provide a fuel cell stack that can be produced industrially advantageously and that is provided with a sealing material that is highly resistant to hydrofluoric acid, and a fuel cell that includes such a fuel cell stack. [Means for solving the problem]

[0009] As a result of extensive research into solving the above problems, the present inventors have found that the following fuel cell stack can achieve the above object, and have completed the present invention. That is, the present invention provides the following fuel cell stack and fuel cell. [1] A fuel cell stack formed by stacking a plurality of fuel cell units, each of which is made up of a pair of separators sandwiching a membrane electrode assembly, wherein a sealing material is disposed on the separator, and the sealing material is a cured product of a curable composition containing a perfluoropolyether compound. [2] The fuel cell stack according to [1], wherein the perfluoropolyether compound has an alkenyl group. [3] The perfluoropolyether compound-containing curable composition comprises (A) a perfluoropolyether polymer having at least two alkenyl groups in one molecule; (B) a fluorine-modified organosilicon compound having two or more hydrogen atoms bonded to silicon atoms in one molecule; (C) a hydrosilylation reaction catalyst, and (D) Reinforcing filler The fuel cell stack according to [1] or [2], comprising: [4] The fuel cell stack according to [3], wherein the component (A) is at least one perfluoropolyether compound selected from the group consisting of perfluoropolyether compounds represented by the following general formula (1) or (2): Rf-(ZWβ)2(1) Rf-(Q-(Y)δ-B)2(2) (In the formula, Rf is a divalent perfluoropolyether group; Z is independently a single bond or a divalent to octavalent organic group which may contain a nitrogen atom, an oxygen atom, a silicon atom, a phosphorus atom, or a sulfur atom and which may be substituted with a halogen atom; W is independently a monovalent organic group having an alkenyl group at its terminal; β is a number from 1 to 7; Q is independently a single bond or a divalent organic group; each δ is independently a number from 1 to 10; Y is independently a divalent organic group having an alkenyl group; and B is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom.) [5] The perfluoropolyether compound-containing curable composition comprises (A) Component: 100 parts by mass, Component (B): an amount such that the amount of hydrogen atoms bonded to silicon atoms (SiH groups) in component (B) is 0.5 to 3 moles per mole of alkenyl groups contained in the composition; Component (C): 0.1 to 2,000 ppm by mass of platinum group metal atoms relative to the mass of component (A); (D) Component: 10 to 40 parts by mass, The fuel cell stack according to [3] or [4], which contains [6] The fuel cell stack according to any one of [3] to [5], wherein the perfluoropolyether compound-containing curable composition further contains (E) a hydrosilylation reaction inhibitor. [7] The fuel cell stack according to any one of [3] to [6], wherein the perfluoropolyether compound-containing curable composition further contains, as an adhesion promoter (F), an organopolysiloxane having, in one molecule, a hydrogen atom directly bonded to a silicon atom (SiH group), a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group, and an epoxy group and / or a trialkoxysilyl group bonded to a silicon atom via a divalent hydrocarbon group which may contain an oxygen atom. [8] A fuel cell comprising the fuel cell stack according to any one of [1] to [7]. [Effects of the Invention]

[0010] According to the present invention, since the sealing material has excellent resistance to hydrofluoric acid, it is possible to provide a fuel cell stack that can maintain excellent sealing properties even during long-term operation, and a fuel cell having the fuel cell stack. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic perspective view of a fuel cell according to an embodiment of the present invention; [Figure 2] 1 is an exploded perspective view of a fuel cell of a fuel cell according to an embodiment of the present invention. [Figure 3] FIG. 2 is a top view of a separator of a fuel cell according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes embodiments of a fuel cell stack according to the present invention. Note that the fuel cell stack according to the present invention is not limited to the following embodiments, and can be embodied in various forms with improvements, omissions, modifications, and the like that can be made by those skilled in the art without departing from the spirit and scope of the present invention.

[0013] FIG. 1 is a perspective view showing a schematic external configuration of a fuel cell according to an embodiment of the present invention.

[0014] As shown in FIG. 1, the fuel cell 100 of this embodiment comprises a plurality of stacked fuel cell cells 200, a pair of end plates 102 that sandwich the plurality of stacked fuel cell cells from the outside in the stacking direction, and fastening members 101 that secure the pair of end plates from the outside in the stacking direction of the fuel cell cells.

[0015] FIG. 2 is an exploded perspective view that schematically shows a fuel cell according to an embodiment of the present invention.

[0016] As shown in FIG. 2, a fuel cell 200 of this embodiment is composed of a membrane electrode assembly (MEA) 202 and a pair of separators 201 sandwiching the membrane electrode assembly (MEA). The membrane electrode assembly (MEA) includes, for example, a fuel gas diffusion layer (GDL: Gas Diffusion Layer) 10a constituting a conductive anode and a fuel electrode catalyst layer (CL: Catalyst Layer) 11a supporting a metal catalyst, an electrolyte membrane 12, and an oxidant gas diffusion layer (GDL) 10b constituting a conductive cathode and an oxidant electrode catalyst layer (CL) 11b supporting a metal catalyst.

[0017] <Electrolyte membrane> The electrolyte membrane 12 is a polymer electrolyte membrane having ion conductivity. Examples of polymer electrolytes that can be used as the polymer electrolyte membrane include aromatic polymers such as tetrafluoroethylene-perfluorovinyl ether sulfonic acid copolymer and sulfonated polyimide, and aliphatic polymers such as polyvinyl sulfonic acid and polyvinyl phosphoric acid. Specific product names of these polymer electrolyte membranes include Nafion (registered trademark) manufactured by DuPont, Aquivion (registered trademark) manufactured by Solvay, Aciplex (registered trademark) manufactured by Asahi Kasei Corporation, and Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd.

[0018] <Gas diffusion layer> The gas diffusion layers 10a and 10b can diffuse the fuel gas or oxidant gas supplied to the flow path uniformly over the entire surface of the catalyst layers 11a and 11b.

[0019] The gas diffusion layer may be made of any material that can be used for a fuel gas diffusion layer or an oxidant gas diffusion layer for a fuel cell. For example, carbon having gas diffusivity, conductivity, and gas permeability, such as carbon paper, carbon cloth, carbon felt, and porous carbon, may be used. Furthermore, the gas diffusion layer may be made of a porous metal such as a metal mesh or a metal foam.

[0020] <Catalyst layer> The catalyst layers 11a and 11b can promote the reaction between the fuel gas and the oxidant gas by the catalyst. The catalyst layers include a catalyst, a carrier that supports the catalyst, and an ionomer that coats these.

[0021] Examples of the catalyst include metals such as platinum, iridium, tungsten, palladium, ruthenium, rhodium, and palladium, as well as mixtures and alloys containing these metals.

[0022] Examples of materials for the support that supports the catalyst include activated carbon, carbon nanowalls, carbon black, carbon nanotubes, carbon nanohorns, glassy carbon, coke, natural graphite, mesocarbon microbeads, mesoporous carbon, glassy carbon powder, and conductive porous metal compounds having pores.

[0023] The ionomer material may be any compound having ion conductivity, such as a compound having a sulfonic group, an imido group, a carboxyl group, or a phosphonic group. Examples of compounds having a sulfonic group include tetrafluoroethylene-perfluorovinyl ether sulfonic acid copolymers, and specific product names include Nafion (registered trademark) manufactured by DuPont, Aquivion (registered trademark) manufactured by Solvay, Aciplex (registered trademark) manufactured by Asahi Kasei Corporation, and Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd. Examples of compounds having an imido group include tetrafluoroethylene-perfluorovinyl ether sulfonimide acid copolymers. Examples of ionomers having a carboxyl group include tetrafluoroethylene-perfluorovinyl ether carboxylic acid copolymers. Examples of compounds having a phosphonic acid group include tetrafluoroethylene-perfluorovinyl ether phosphonic acid copolymers.

[0024] <Separator> FIG. 3 is a top view that schematically shows a separator of a fuel cell according to an embodiment of the present invention.

[0025] 3, the separator 201 is provided with an oxidant gas inlet 20a, an oxidant gas outlet 20b, a coolant inlet 21a, a coolant outlet 21b, a fuel gas inlet 22b, a fuel gas outlet 22a, and a flow channel 23. In addition, the separator 201 is provided with a sealing material 30.

[0026] The separator is made of a gas-impermeable conductive material, such as a carbon separator or a metal separator.

[0027] Carbon separators can be made by mixing and dispersing a conductive filler, carbon powder, into a resin base material, and then press-molding the resulting composite into a flat plate with gas and cooling medium flow paths. The carbon powder is not particularly limited, and examples of suitable carbon separators include artificial graphite, lump graphite, expanded graphite, flake graphite, acetylene black, carbon black, kish graphite, ketjen black, coke powder, and mixtures thereof. The resin material is not particularly limited, and examples include thermosetting resins such as phenolic resin, polyethylene resin, and polypropylene resin, and thermoplastic resins such as polyphenylene sulfide resin and tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin.

[0028] Examples of metal separators include those obtained by press-molding a metal substrate into a flat plate shape in which gas and cooling medium flow paths are formed. The metal constituting the metal substrate is not particularly limited, and examples include aluminum, cobalt, chromium, zirconium, tungsten, titanium, iron, copper, manganese, molybdenum, nickel, and alloys of two or more of these metals. Titanium and stainless steel are preferred due to their high electrical conductivity and corrosion resistance. Stainless steel is an alloy primarily composed of iron and containing 10.5% or more chromium. Examples of stainless steel include austenitic, ferritic, martensitic, and austenitic-ferritic two-phase stainless steels.

[0029] From the viewpoint of corrosion resistance, etc., the metal substrate may have a plated layer formed on the surface by a metal plating process. Examples of metal plating include tin plating, nickel plating, or multi-layer plating and alloy plating thereof.

[0030] The average thickness of the separator is not particularly limited, but can be, for example, 0.05 to 0.5 mm. If the average thickness of the separator is too thin, the rigidity of the separator will be insufficient, making it difficult to maintain a predetermined shape. Also, if the average thickness of the separator is too thick, it will be disadvantageous in terms of size and weight reduction.

[0031] In the separator 201, an oxidant gas inlet 20a, a coolant inlet 21a, and a fuel gas outlet 22a are arranged in the direction A1, which is one end of the arrow A, from B1, which is one end of the arrow B, to B2, which is the other end of the arrow B.

[0032] The oxidant gas inlets 20a of the separators 201 are connected to each other in the direction of arrow C, which is the stacking direction of the separators 201, and supply an oxidant gas (e.g., air, oxygen, etc.). The coolant inlets 21a of the separators 201 are connected to each other in the direction of arrow C and supply a coolant (e.g., ethylene glycol, oil, pure water, etc.). The fuel gas outlets 22a of the separators 201 are connected to each other in the direction of arrow C and discharge a fuel gas (e.g., hydrogen, etc.).

[0033] In the separator 201, in the direction A2, which is one end of the arrow A, the oxidant gas outlet 20b, the coolant outlet 21b, and the fuel gas inlet 22b are lined up from the direction B2, which is one end of the arrow B, to the direction B1, which is the other end of the arrow B.

[0034] The oxidant gas outlets 20b of each separator 201 are connected to each other in the direction of arrow C, which is the stacking direction of the multiple separators 201, and discharge an oxidant gas (e.g., air, oxygen, etc.). The coolant outlets 21b of each separator 201 are connected to each other in the direction of arrow C and discharge a coolant (e.g., ethylene glycol, oil, pure water, etc.). The fuel gas inlets 22b of each separator 201 are connected to each other in the direction of arrow C and supply a fuel gas (e.g., hydrogen, etc.).

[0035] The positions, shapes, sizes, and numbers of the cooling medium inlet, cooling medium outlet, oxidant gas inlet, oxidant gas outlet, fuel gas inlet, and fuel gas outlet are not limited to those in this embodiment, and can be set appropriately according to the intended design specifications.

[0036] <Gas flow path> The gas flow path is a flow path that a fuel cell separator has in order to supply a reactant gas, such as an oxidant gas or a fuel gas, supplied from outside the fuel cell to the gas diffusion layer and to discharge these gases to the outside of the fuel cell.

[0037] <Fuel Cell Operation> An oxidant gas flows through the flow channels formed in the separator, and is supplied to the separator. The oxidant gas then passes through the gas diffusion layer and flows to the catalyst layer. A fuel gas also flows through the flow channel grooves formed in the separator, and is supplied to the anode. The fuel gas also passes through the gas diffusion layer and flows to the catalyst layer. The supply of fuel gas and oxidant gas causes an electrochemical reaction, generating a DC voltage between the anode and cathode.

[0038] <Areas where sealing material is placed> The fuel cell stack of the present invention includes a sealant, which is a cured product of a perfluoropolyether compound-containing curable composition, disposed at least on a separator. While FIG. 3 shows an example of a sealant 30 disposed around the oxidant gas inlet 20a, oxidant gas outlet 20b, coolant inlet 21a, coolant outlet 21b, fuel gas inlet 22b, fuel gas outlet 22a, and flow channel 23 of the separator, the location of the sealant is not limited thereto. That is, the location of the sealant may be determined depending on the type and structure of the fuel cell. That is, the sealant of the fuel cell stack of the present invention can be used in locations requiring airtightness, liquidtightness, etc. Furthermore, the sealant of the fuel cell stack of the present invention may be disposed in all locations requiring sealing, or in only some of the locations requiring sealing. Examples of locations to be sealed include between components constituting adjacent fuel cells, between a pair of separators sandwiching an MEA, between an electrolyte membrane and a separator, and around the MEA.

[0039] <Sealing material> Next, the sealing material (cured product of the perfluoropolyether compound-containing curable composition) will be described in detail. The perfluoropolyether compound contained in the perfluoropolyether compound-containing curable composition preferably has an alkenyl group. The perfluoropolyether compound-containing curable composition preferably contains the following components (A), (B), (C), and (D), and may optionally further contain components (E), (F), and / or other components. [Component (A)] The component (A) is a perfluoropolyether polymer having at least two alkenyl groups in one molecule, and is the main component (base polymer) of the perfluoropolyether compound-containing curable composition used as a sealing material.

[0040] The alkenyl group contained in component (A) preferably has 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms, and has a CH═CH- structure. Examples include vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, and hexenyl groups, with vinyl groups and allyl groups being particularly preferred.

[0041] The alkenyl group content of component (A) is preferably 0.005 to 0.3 mol / 100g, and more preferably 0.007 to 0.2 mol / 100g. If the alkenyl group content is 0.005 mol / 100g or more, the degree of crosslinking of the composition is sufficient, and there is no risk of curing defects. On the other hand, if the alkenyl group content is 0.3 mol / 100g or less, there is no risk of the mechanical properties of the cured product (perfluoropolyether rubber elastomer) obtained by curing the composition being impaired. The alkenyl group content of component (A) is 1 It can be calculated from H-NMR measurements.

[0042] The perfluoropolyether structure contained in the main chain of component (A) is -C a F 2a O- (In the formula, a is a number from 1 to 6.) The compound contains a large number of repeating units (perfluorooxyalkylene units) represented by the following formula (3), for example. -(C a F 2a O) b - (3) (In formula (3), a is a number from 1 to 6, and b is a number from 1 to 300, preferably a number from 1 to 200.)

[0043] Above-C a F 2a Examples of the repeating unit represented by O- include units represented by the following formulas. -CF2O- -CF2CF2O- -CF2CF2CF2O- -CF(CF3)CF2O- -CF(CF3)OCF2- -CF2OCF(CF3)- -CF2CF2CF2CF2O- -CF2CF2CF2CF2CF2O- -CF2CF2CF2CF2CF2CF2O- -C(CF3)2O-

[0044] Among these, the repeating units represented by the following formula are particularly preferred. -CF2O- -CF2CF2O- -CF2CF2CF2O- -CF(CF3)CF2O- -CF(CF3)OCF2- -CF2OCF(CF3)-

[0045] The perfluoropolyether structure contained in the component (A) may be composed of one type of the above repeating unit, or may be composed of a combination of two or more types.

[0046] Suitable examples of the perfluoropolyether polymer having at least two alkenyl groups in one molecule of the component (A) include perfluoropolyether compounds represented by the following general formula (1) or (2). Rf-(ZWβ)2(1) Rf-(Q-(Y)δ-B)2(2) In formula (1), Rf is a divalent perfluoropolyether group, Z is independently a single bond or a divalent to octavalent organic group which may contain a nitrogen atom, an oxygen atom, a silicon atom, a phosphorus atom, or a sulfur atom and may be fluorinated, and W is independently a monovalent organic group having an alkenyl group at its terminal. β is a number from 1 to 7, preferably β is a number from 1 to 3. In formula (2), Rf is a divalent perfluoropolyether group, Q is independently a single bond or a divalent organic group, δ is independently a number from 1 to 10, Y is independently a divalent organic group having an alkenyl group, and B is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom.

[0047] In the above formulas (1) and (2), Rf is a divalent perfluoropolyether group, and examples thereof include one or a combination of two or more of the groups represented by the above general formula (3). Rf is preferably a group represented by the following formula: {-CF(CF3)OCF2-} a {-CF2OCF(CF3)-} b (In the above formula, a and b are each a number of 1 or more, and a+b is 2 to 300.) {-CF2O-} p {-CF2CF2O-} q (In the above formula, p and q are each a number of 1 or more, and p+q is 2 to 300.) {-CF2CF2CF2O-} p' (In the above formula, p' is a number from 2 to 300.) {-CF2CF2CF2CF2O-} p' ' {-CF2CF2O-} q' ' (In the above formula, p'' and q'' are each a number of 1 or more, and p''+q'' is 2 to 300.)

[0048] In the above formula (1), Z is independently a single bond or a divalent to octavalent organic group which may contain a nitrogen atom, an oxygen atom, a silicon atom, a phosphorus atom or a sulfur atom and may be substituted with a halogen atom. The divalent to octavalent organic group is (L) e -M (e is a number from 1 to 7, preferably a number from 1 to 3).

[0049] Here, L is a single bond, a carbonyl bond, an oxygen atom, a sulfur atom or a divalent organic group, and is a linking group between the Rf group and the M group (or the W group). The divalent organic group represented by L is preferably an unsubstituted or substituted divalent hydrocarbon group having 2 to 12 carbon atoms. Examples of the divalent hydrocarbon group having 2 to 12 carbon atoms include alkylene groups such as ethylene, propylene (trimethylene, methylethylene), butylene (tetramethylene, methylpropylene), hexamethylene, and octamethylene, arylene groups such as phenylene, and combinations of two or more of these groups (e.g., alkylene-arylene groups). The divalent hydrocarbon group having 2 to 12 carbon atoms includes an amide bond, an ether bond, a carbonyl bond, an ester bond, a diorganosilylene group such as a dimethylsilylene group, and —Si[OH][(CH2) f Si(CH3)3]- (f is a number from 2 to 4), or may be a group in which some or all of the hydrogen atoms bonded to the carbon atoms have been substituted with halogen atoms such as fluorine or iodine. Of these, unsubstituted or substituted alkylene groups and phenylene groups having 2 to 4 carbon atoms, and combinations thereof are preferred. The number of carbon atoms in a divalent hydrocarbon group having 2 to 12 carbon atoms, which is preferred as a divalent organic group, is the number of carbon atoms in the unsubstituted divalent hydrocarbon group; for example, when the divalent hydrocarbon group contains the above structure such as a dimethylsilylene group, the number of carbon atoms in the above structure is not counted.

[0050] Examples of L include groups represented by the following structures, and groups in which two or more of these are bonded together. [ka] [ka] [ka] [ka] [ka] (In the formula, f is a number from 2 to 4, b is a number from 2 to 6, preferably a number from 2 to 4, u and v each independently is a number from 1 to 4, g is a number from 2 to 4, and Me is a methyl group.)

[0051] M is a single bond, a nitrogen atom, a silicon atom, a carbon atom, a phosphorus atom, or a divalent to octavalent (the above (e+1) valent) organic group which may contain at least one of a nitrogen atom, a silicon atom, a carbon atom, and a phosphorus atom. 1 a divalent group represented by 2C-, -R 3 A divalent group represented by 2Si-, -NR 4 A divalent group represented by -, a trivalent group represented by -N=, a trivalent group represented by -P=, a trivalent group represented by -PO=, -R 1 A trivalent group represented by C=, -R 3 It is a group selected from a trivalent group represented by Si=, a tetravalent group represented by -C≡, a tetravalent group represented by -OC≡, and a tetravalent group represented by -Si≡, or a divalent to octavalent siloxane residue, and in the above formula (1), M of Z is a linking group between L (or Rf group) and W group.

[0052] In the above, R 1 are each independently preferably a group having a repeating unit of an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, or an oxyalkylene group having 1 to 3 carbon atoms which may be interrupted by a diorganosiloxane structure having 2 to 51 silicon atoms, or R2 3SiO-, and R 2 are each independently a hydrogen atom, an alkyl group preferably having 1 to 3 carbon atoms, an aryl group such as a phenyl group, or an alkoxy group having 1 to 3 carbon atoms. 3 are each independently preferably an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 or 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a chloro group. 4 is an alkyl group having 1 to 3 carbon atoms, or an aryl group having 6 to 10 carbon atoms, such as a phenyl group. When M is a siloxane residue, it preferably has a linear, branched, or cyclic organopolysiloxane structure having 2 to 51 silicon atoms, preferably 2 to 13 silicon atoms, more preferably 2 to 11 silicon atoms, and even more preferably 2 to 5 silicon atoms. The organopolysiloxane preferably has an unsubstituted or fluorine-substituted alkyl group or phenyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, such as a methyl group, ethyl group, propyl group, or butyl group, or C3F7-C3H6-. In addition, it is preferable to use a silalkylene structure in which two silicon atoms are bonded by an alkylene group, i.e., Si-(CH2) n In the above formula, n is a number from 2 to 6, and preferably a number from 2 to 4.

[0053] Examples of such M include the following: [ka] [ka] [ka] [ka] [ka] [ka] [ka] (In the formula, i is a number from 1 to 20, c is a number from 1 to 50, and Me is a methyl group.)

[0054] In the above formula (1), W is a monovalent organic group having an alkenyl group at the terminal, and is preferably represented by the following formula: [ka] (In the formula, R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a hydroxy group, a methyl group, or an ethyl group, or a phenyl group. X is an alkenyl group. a is a number from 1 to 3, and m is a number from 0 to 10.) Examples of the alkenyl group represented by X include a vinyl group, an allyl group, and a 3-butenyl group.

[0055] In formula (1), examples of the structure represented by -ZWβ include the following structures. [ka] [ka] (In the formula, L, R, X, f, and a are as defined above, m1 is a number from 0 to 10, preferably a number from 2 to 8, m2 is a number from 1 to 10, preferably a number from 2 to 8, and Me is a methyl group.)

[0056] In the above formula (2), Q is a single bond or a divalent organic group, and is a linking group between the Rf group and the Y group. The divalent organic group of Q is preferably an amide bond, an ether bond, an ester bond, a diorganosilylene group such as a dimethylsilylene group, or —Si[OH][(CH) f Si(CH3)3]- (f is a number from 2 to 4), and more preferably an unsubstituted or substituted divalent organic group having 2 to 12 carbon atoms that may contain the structure.

[0057] Examples of the unsubstituted or substituted divalent hydrocarbon group having 2 to 12 carbon atoms include the same unsubstituted or substituted divalent hydrocarbon groups having 2 to 12 carbon atoms as exemplified for L above.

[0058] Examples of the divalent organic group for Q include groups represented by the following structures: [ka] [ka] [ka] [ka] (In the formula, f is a number from 2 to 4, b is a number from 2 to 6, preferably a number from 2 to 4, u and v are numbers from 1 to 4, g is a number from 2 to 4, and Me is a methyl group.)

[0059] In the above formula (2), Y's are each independently a divalent organic group having an alkenyl group, and preferably have a structure represented by the following formula: [ka] (In the formula, R, X, and a are as defined above. k is a number from 0 to 10, preferably a number from 1 to 10, and more preferably a number from 2 to 8. h is a number from 1 to 6, preferably 1 or 2. M' is an unsubstituted or substituted trivalent to octavalent, preferably trivalent or tetravalent, hydrocarbon group in which some or all of the carbon atoms may be replaced with silicon atoms, and in which some or all of the hydrogen atoms bonded to the carbon atoms may be replaced with halogen atoms such as fluorine atoms.) M' is preferably a group represented by the following structure.

[0060] [ka] (In the above, M 1is a single bond, an unsubstituted or substituted divalent hydrocarbon group having 1 to 6 carbon atoms, or a diorganosilylene group such as a dimethylsilylene group, and M 2 Ha-R 1 A trivalent group represented by C= or -R 3 Si= is a trivalent group represented by R 1 , R 3 is the same as above. R 5 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, such as an alkyl group, e.g., a methyl group, an ethyl group, or a propyl group.

[0061] M 1 Examples of the group include a single bond, a phenylene group, a dimethylsilylene group, and a tetrafluoroethylene group. 2 Examples of such substances include the following: [ka] (In the formula, Me is a methyl group.)

[0062] Examples of such Y include the following groups. [ka] (In the formula, X is the same as above, k1 is a number from 0 to 10, preferably a number from 1 to 8, k2 is a number from 2 to 10, preferably a number from 2 to 8, Me is a methyl group, and some or all of the silicon atoms in the formula may be replaced with carbon atoms.)

[0063] In the above formula (2), each δ is independently a number from 1 to 10, preferably a number from 1 to 4.

[0064] In the above formula (2), each B is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, or a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0065] Examples of the alkenyl group-containing perfluoropolyether compound represented by the above formula (1) or (2) include the following.

[0066] [ka] [ka] [ka] [ka] [ka] [ka] [ka] (In the formula, p1, q1, r1, and s1 each independently represent an integer of 1 to 200, and the total of p1, q1, r1, and s1 is 3 to 300, and the repeating units shown in parentheses may be bonded randomly.)

[0067] [ka] [ka] [ka] (In the formula, c1 and d1 are each a number from 1 to 150, and the sum of c1 and d1 is 2 to 300, and the repeating units shown in parentheses may be bonded randomly.)

[0068] [ka] [ka] (In the formula, c2 and d2 are each a number from 1 to 150, and the sum of c2 and d2 is 2 to 300, and the repeating units shown in parentheses may be bonded randomly.)

[0069] [(B) Component] Component (B) is a fluorine-modified organosilicon compound having two or more hydrogen atoms bonded to silicon atoms (hydrosilyl groups represented by SiH) in each molecule, and acts as a crosslinking agent (curing agent) capable of undergoing a hydrosilylation addition reaction with component (A) in the perfluoropolyether compound-containing curable composition that is the sealing material of the present invention. Component (B) is preferably an organosilicon compound (particularly a fluorine-containing organohydrogenpolysiloxane) that has, in one molecule, a monovalent perfluoroalkyl group having 2 or more carbon atoms (i.e., 5 or more fluorine atoms) or a monovalent perfluorooxyalkyl group having 1 or more carbon atoms (i.e., 3 or more fluorine atoms), or a divalent perfluoroalkylene group having 2 or more carbon atoms (i.e., 4 or more fluorine atoms) or a divalent perfluorooxyalkylene group having 2 or more carbon atoms (i.e., 4 or more fluorine atoms), and that has, in one molecule, two or more hydrogen atoms (SiH groups) directly bonded to silicon atoms, and that does not have epoxy groups or alkoxy groups directly bonded to silicon atoms.

[0070] The above-mentioned monovalent perfluoroalkyl groups, monovalent perfluorooxyalkyl groups, divalent perfluoroalkylene groups and divalent perfluorooxyalkylene groups are groups that are introduced from the viewpoints of compatibility with the above-mentioned component (A), dispersibility, uniformity after curing, etc.

[0071] Examples of the monovalent perfluoroalkyl group or monovalent perfluorooxyalkyl group include groups represented by the following general formula (4) or (5). C f F 2f+1 - (4) (In formula (4), f is a number from 2 to 10, preferably a number from 3 to 7.) [ka] (In formula (5), g is a number from 1 to 50, and preferably a number from 2 to 30.)

[0072] Furthermore, examples of the divalent perfluoroalkylene group or divalent perfluorooxyalkylene group include groups represented by the following general formulas (6) to (8). -C h F 2h - (6) (In formula (6), h is a number from 2 to 20, preferably a number from 2 to 10.) [ka] (In formula (7), i and j are each a number of 1 or more, preferably a number of 1 to 100, and the average value of i+j is 2 to 200, preferably 2 to 100.) -CF2O-(CF2CF2O) k (CF2O) l -CF2- (8) (In formula (8), k and l each represent a number from 1 to 50, preferably a number from 1 to 30, and the average value of k+l is 2 to 100, preferably 2 to 60. The repeating units may be bonded to each other randomly.)

[0073] Furthermore, these perfluoroalkyl groups, perfluorooxyalkyl groups, perfluoroalkylene groups, or perfluorooxyalkylene groups (hereinafter collectively referred to as "monovalent or divalent fluorine-containing organic groups") are preferably linked to the silicon atoms constituting the polysiloxane via a divalent linking group. The divalent linking group is preferably an unsubstituted or substituted divalent hydrocarbon group having 2 to 13 carbon atoms, particularly 2 to 8 carbon atoms, which may contain an oxygen atom, a nitrogen atom, or a silicon atom. Specific examples include alkylene groups, arylene groups, and combinations thereof, as well as groups in which one or more structures selected from the group consisting of an ether-bonded oxygen atom, an amide bond, a carbonyl bond, an ester bond, and a diorganosilylene group such as a dimethylsilylene group are interposed, such as the following: -CH2CH2- -CH2CH2CH2- -CH2CH2CH2OCH2- -CH2CH2CH2-NH-CO- -CH2CH2CH2-N(Ph)-CO- -CH2CH2CH2-N(CH3)-CO- -CH2CH2CH2-N(CH2CH3)-CO- -CH2CH2CH2-N(CH(CH3)2)-CO- -CH2CH2CH2-O-CO- -CH2CH2-Si(CH3)2-Ph'-N(CH3)-CO- -CH2CH2CH2-Si(CH3)2-Ph'-N(CH3)-CO- (wherein Ph is a phenyl group and Ph' is a phenylene group.)

[0074] In the fluorine-modified organosilicon compound of component (B), the monovalent or divalent fluorine-containing organic group and the monovalent substituent bonded to the silicon atom other than the hydrogen atom directly bonded to the silicon atom are unsubstituted or substituted alkyl or aryl groups having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, cyclohexyl, octyl, and decyl; aryl groups such as phenyl, tolyl, and naphthyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as chlorine atoms or cyano groups, such as chloromethyl, chloropropyl, and cyanoethyl. Among these, methyl groups are preferred. Component (B) does not contain epoxy or alkoxy groups.

[0075] The structure of the fluorine-modified organosilicon compound of component (B) may be cyclic, linear, three-dimensional network, or a combination thereof. The number of silicon atoms in this fluorine-modified organosilicon compound is not particularly limited, but is usually 2 to 60, preferably 3 to 30, and more preferably 4 to 30. Furthermore, component (B) has two or more, preferably three or more, SiH groups per molecule, and the SiH group content is preferably 0.0001 to 0.02 mol / g, and more preferably 0.0002 to 0.01 mol / g.

[0076] Examples of the component (B) include those represented by the following general formulas (9) to (15). [ka] In formula (9), each A is independently a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group bonded to a silicon atom constituting the polysiloxane via a divalent hydrocarbon group which may have an oxygen atom, a nitrogen atom, or a silicon atom. Examples of the monovalent perfluoroalkyl group or the monovalent perfluorooxyalkyl group include groups represented by the above general formula (4) or (5). R 6 are each independently an unsubstituted or substituted alkyl group or aryl group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms. m is a number from 2 to 6, preferably 3 to 6, n is a number from 1 to 4, preferably 1 to 3, and m+n is a number from 4 to 10, preferably 4 to 9. However, -(Si(H)(R 6 )O)- and -(Si(A)(R 6 The bonding order of )O)- is not limited. [ka] (In formula (10), A's are each independently the same as A's above, and R 6 are independent of each other, and the above R 6 In addition, o is a number from 2 to 50, preferably a number from 3 to 30. [ka] (In formula (11), A's are each independently the same as A's above, and R 6 are independent of each other, and the above R 6where o is a number from 2 to 50, preferably a number from 3 to 30, p is a number from 1 to 40, preferably a number from 1 to 20, and o+p is a number from 4 to 60, preferably a number from 4 to 50. However, -(Si(H)(R 6 )O)- and -(Si(A)(R 6 The bonding order of )O)- is not limited. [ka] (In formula (12), A's are each independently the same as A's above, and R 6 are independent of each other, and the above R 6 where o is a number from 2 to 50, preferably a number from 3 to 30, q is a number from 1 to 40, preferably a number from 1 to 20, and o+q is a number from 4 to 60, preferably a number from 4 to 50. However, -(Si(H)(R 6 )O)- and -(Si(R 6 The order of bonding of )2O)- is not limited. [ka] (In formula (13), A's are each independently the same as A's above, and R 6 are independent of each other, and the above R 6 where o is a number from 2 to 50, preferably a number from 3 to 30, p is a number from 1 to 40, preferably a number from 1 to 20, q is a number from 1 to 40, preferably a number from 1 to 20, and o+p+q is a number from 5 to 60, preferably a number from 5 to 50. However, -(Si(H)(R 6 )O)-, -(Si(A)(R 6 )O)- and -(Si(R 6 The order of bonding of )2O)- is not limited. [ka] In formula (14), D is a divalent perfluoroalkylene group or a divalent perfluorooxyalkylene group bonded to adjacent silicon atoms via an oxygen atom, an alkylene group, or a divalent hydrocarbon group which may have an oxygen atom or a nitrogen atom. Examples of the divalent perfluoroalkylene group or the divalent perfluorooxyalkylene group include any of the groups represented by the above general formulae (6) to (8). Each A is independently the same as the above A, and R 6 are independent of each other, and the above R 6 In addition, r is a number from 0 to 3, s is a number from 0 to 3, and r+s is a number from 2 to 6, preferably a number from 3 to 5. [ka] (In formula (15), A is the same as A above, and R 6 are independent of each other, and the above R 6 is the same as

[0077] Specific examples of component (B) include the following compounds. These compounds may be used alone or in combination of two or more. In the following formula, Me represents a methyl group, Ph represents a phenyl group, f' is a number from 2 to 10, g' is a number from 1 to 50, h' is a number from 1 to 20, i' and j' are each a number from 1 to 100, i' + j' is a number from 2 to 200, k' and l' are each a number from 1 to 50, and k' + l' is a number from 2 to 100.

[0078] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0079] This component (B) may be used alone or in combination of two or more. The amount of component (B) is preferably such that the silicon-bonded hydrogen atoms (SiH groups) in component (B) are 0.5 to 3 moles, and more preferably 0.6 to 2 moles, per mole of alkenyl groups (particularly alkenyl groups in component (A)) contained in the composition of the present invention (molar ratio). Fewer than 0.5 moles of SiH groups may result in an insufficient degree of crosslinking in the cured product, whereas more than 3 moles may impair the storage stability of the composition or reduce the heat resistance of the cured product obtained after curing.

[0080] [(C) component] The hydrosilylation catalyst, component (C), promotes the addition reaction between components (A) and (B). This hydrosilylation catalyst is generally a noble metal (particularly a platinum group metal) or a compound thereof, and is expensive, so platinum or a platinum compound is often used, which is relatively easy to obtain.

[0081] Examples of platinum compounds include chloroplatinic acid, complexes of chloroplatinic acid with olefins such as ethylene, complexes of chloroplatinic acid with alcohols or vinylsiloxanes, and metallic platinum supported on silica, alumina, carbon, etc. Other than platinum or its compounds, rhodium, ruthenium, iridium, and palladium-based compounds are also known as hydrosilylation catalysts, such as RhCl(PPh3)3, RhCl(CO)(PPh3)2, and Ru3(CO) 12 Examples include IrCl(CO)(PPh3)2, Pd(PPh3)4, etc. In the above formula, Ph is a phenyl group.

[0082] When using these catalysts, if they are solid catalysts they can be used in solid form; however, to obtain a more uniform cured product, it is preferable to use chloroplatinic acid or a complex dissolved in a suitable solvent such as toluene or ethanol, and then use the solution dissolved in component (A).

[0083] The component (C) may be used alone or in combination of two or more types. The amount of these catalysts used is not particularly limited, and the desired curing rate can be obtained with any amount of catalyst. From an economical standpoint or to obtain a good cured product, the amount is usually 0.1 to 2,000 ppm, preferably 0.1 to 500 ppm, and particularly preferably 0.5 to 200 ppm (calculated as the mass of platinum group metal atoms) relative to the mass of component (A), but this amount can be increased or decreased as appropriate depending on the desired curing rate.

[0084] The conditions for the above addition reaction (hydrosilylation reaction) can be selected appropriately, and the reaction may be carried out at room temperature, but can also be carried out by heating to 50 to 200°C to accelerate the reaction.

[0085] [(D) component] Component (D) is a reinforcing filler. Examples of reinforcing fillers include silica-based reinforcing fillers, quartz powder, fused quartz powder, diatomaceous earth, calcium carbonate, and other reinforcing or semi-reinforcing fillers. Examples of silica-based reinforcing fillers include silica powders such as fumed silica (fumed silica or dry silica), precipitated silica (wet silica), spherical silica (fused silica), sol-gel silica, and silica aerogel, as well as silica powders (surface-treated silica powders) obtained by treating the surface of the silica powder with various organochlorosilanes, organodisilazanes, cyclic organopolysilazanes, and the like. Furthermore, the silica-based reinforcing filler may be a silica powder obtained by re-treating the surface-treated silica powder with an organosilane or organosiloxane having a monovalent perfluoroalkyl group represented by the above general formula (4) or a monovalent perfluorooxyalkyl group represented by the above general formula (5). Of these, fumed silica is particularly preferred as component (D) from the viewpoints of improving mechanical strength and improving dispersion stability of each component. Furthermore, from the viewpoint of improving dispersibility, fumed silica treated with a silicon compound surface treatment agent such as silane is preferred, and in particular, fumed silica hydrophobized with silicon compounds having hydrolyzable groups, such as organochlorosilanes such as dimethyldichlorosilane and trimethylchlorosilane, silazane compounds such as hexamethyldisilazane, and cyclic silazanes such as hexamethylcyclotrisilazane is preferred.

[0086] In this hydrophobic treatment, the silica powder whose surface has been treated with a surface treatment agent is preferably one that has been treated directly in the powder state in advance, and the usual treatment method can be a well-known technique, for example, by placing the untreated silica powder and the treatment agent in a mechanical kneading device sealed at atmospheric pressure or in a fluidized bed, mixing them at room temperature or by heat treatment in the presence of an inert gas as needed, optionally using a catalyst and water to promote hydrolysis, and then drying to prepare the resulting mixture. The amount of the surface treatment agent to be added should be equal to or greater than the amount calculated from the area that the surface treatment agent can cover on the surface of the silica powder.

[0087] The specific surface area of the silica powder by the BET method was set at 50m to improve the mechanical properties. 2 / g or more, and further, when silica powder is blended into the composition, the viscosity increases significantly, making blending difficult. 2 / g or less is preferable.

[0088] The component (D) may be used alone or in combination of two or more types.

[0089] Furthermore, the bulk density of the reinforcing filler is preferably 30 to 80 g / L. If the bulk density of the reinforcing filler is less than 30 g / L, the viscosity of the composition increases, which may make it difficult to blend, while if it exceeds 80 g / L, a sufficient reinforcing effect may not be imparted.

[0090] The amount of this reinforcing filler to be blended is preferably 10 to 40 parts by mass, and more preferably 15 to 30 parts by mass, per 100 parts by mass of component (A). If the amount is less than 10 parts by mass, the mechanical strength of the cured product may be insufficient, while if the amount is more than 40 parts by mass, the viscosity of the composition may increase significantly, making it difficult to blend the reinforcing filler.

[0091] [(E) component] Component (E) is a hydrosilylation reaction inhibitor, an optional component that can be incorporated as needed. Examples of hydrosilylation addition reaction inhibitors include acetylenic alcohols such as 1-ethynyl-1-cyclohexanol, 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, and phenylbutynol; reaction products of chlorosilanes having a monovalent perfluoroalkyl group represented by the general formula (4) above or a monovalent perfluorooxyalkyl group represented by the general formula (5) above with acetylenic alcohols; acetylenic compounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne, and triallyl isocyanurate; polyvinylsiloxane; and organophosphorus compounds. The addition of these compounds can maintain appropriate curing reactivity and storage stability. Component (E) can be used alone or in combination. When component (E) is added, the amount added is arbitrary as long as it does not impair the object of the present invention.

[0092] [Component (F)] Component (F) is an optional component that is blended as needed, and acts as an adhesion promoter that imparts self-adhesion to the cured product obtained by curing the perfluoropolyether compound-containing curable composition that is the sealing material of the present invention. Component (F) is an organopolysiloxane that has, in one molecule, a hydrogen atom directly bonded to a silicon atom, a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group, and an epoxy group or a trialkoxysilyl group, or both, bonded to a silicon atom via a divalent hydrocarbon group that may contain an oxygen atom.

[0093] The monovalent perfluoroalkyl group or monovalent perfluorooxyalkyl group is a group that is introduced from the viewpoints of compatibility with the component (A), dispersibility, uniformity after curing, and the like. Examples of this monovalent perfluoroalkyl group or monovalent perfluorooxyalkyl group include groups represented by the above-mentioned general formula (4) or (5).

[0094] The monovalent perfluoroalkyl group or monovalent perfluorooxyalkyl group is preferably linked to a silicon atom constituting the polysiloxane via a divalent hydrocarbon group (linking group) which may contain a silicon atom, an oxygen atom, and a nitrogen atom. The divalent hydrocarbon group may be an alkylene group, an arylene group, or a combination thereof, or may be one in which one or more structures selected from the group consisting of an ether-bonded oxygen atom, an amide bond, a carbonyl bond, an ester bond, and a diorganosilylene group such as a dimethylsilylene group are interposed between these groups, for example: -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2OCH2-, -CH2CH2CH2-NH-CO-, -CH2CH2CH2-N(Ph)-CO-, -CH2CH2CH2-N(CH3)-CO-, -CH2CH2CH2-N(CH2CH3)-CO-, -CH2CH2CH2-N(CH(CH3)2)-CO-, -CH2CH2CH2-O-CO-, -CH2CH2CH2-Si(CH3)2-O-Si(CH3)2-CH2CH2CH2-, -CH2OCH2CH2CH2-Si(CH3)2-O-Si(CH3)2-CH2CH2-, -CO-N(CH3)-Ph'-Si(CH3)2-CH2CH2-, -CO-N(CH3)-Ph'-Si(CH3)2-CH2CH2-Si(CH3)2-O-Si(CH3)2-CH2CH2-, -CO-NH-Ph'-[Si(CH3)2-CH2CH2]3-CH2-, -CO-N(CH3)-Ph'-[Si(CH3)2-CH2CH2]3- (wherein Ph is a phenyl group and Ph' is a phenylene group.) and the like, each having 2 to 20 carbon atoms.

[0095] The organopolysiloxane of component (F) is preferably a cyclic organopolysiloxane represented by the following general formula (16). [ka] (In the formula, i" is a number from 1 to 6, preferably a number from 1 to 5, j" is a number from 1 to 4, preferably a number from 1 to 3, k" is a number from 1 to 4, preferably a number from 1 to 3, and i"+j"+k" is a number from 4 to 10, preferably a number from 4 to 8. In addition, R 13 are each independently an unsubstituted or substituted monovalent hydrocarbon group, each T is each independently a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group bonded to a silicon atom via a divalent hydrocarbon group which may contain a silicon atom, an oxygen atom, and a nitrogen atom, and each X is each independently an epoxy group or a trialkoxysilyl group bonded to a silicon atom via a divalent hydrocarbon group which may contain an oxygen atom, provided that -(SiO)(H)R 13 -, -(SiO)(T)R 13 - and -(SiO)(X)R 13 The order of bonding is not limited.)

[0096] In the above general formula (16), R 13 are each independently an unsubstituted or substituted monovalent hydrocarbon group, such as the above-mentioned R 6 Examples include unsubstituted or substituted alkyl or aryl groups having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, as in the above, and particularly preferred are methyl and ethyl groups.

[0097] Furthermore, each T is independently a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group bonded to a silicon atom via a divalent hydrocarbon group which may contain a silicon atom, an oxygen atom, and a nitrogen atom. Examples of this monovalent perfluoroalkyl group or monovalent perfluorooxyalkyl group include groups represented by the above-mentioned general formula (4) or (5).

[0098] Furthermore, X's are each independently an epoxy group or a trialkoxysilyl group bonded to a silicon atom via a divalent hydrocarbon group which may contain an oxygen atom. Examples of such epoxy groups include those represented by the following general formula (17) and alicyclic epoxy groups. [ka]

[0099] In the above general formula (17), R 14 is a divalent hydrocarbon group which may have an oxygen atom interposed therebetween and preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms. Specific examples include alkylene groups such as methylene, ethylene, propylene (trimethylene, methylethylene), butylene (tetramethylene, methylpropylene), hexylene (hexamethylene), and octylene (octamethylene); cycloalkylene groups such as cyclohexylene; and oxyalkylene groups such as oxyethylene, oxypropylene, and oxybutylene.

[0100] Specific examples of such epoxy groups include those shown below. [ka]

[0101] The alicyclic epoxy group is preferably an epoxycyclohexyl group represented by the following formula (18). [ka]

[0102] On the other hand, examples of the trialkoxysilyl group include those represented by the following general formula (19). -R 15 -Si(OR 16 )3(19)

[0103] In the above general formula (19), R 15is preferably a divalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and specific examples thereof include alkylene groups such as methylene, ethylene, propylene (trimethylene, methylethylene), butylene (tetramethylene, methylpropylene), hexylene (hexamethylene), cyclohexylene, and octylene (octamethylene). 16 is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and specific examples thereof include alkyl groups such as a methyl group, an ethyl group, and an n-propyl group.

[0104] Specific examples of such trialkoxysilyl groups include those shown below. -(CH2)2-Si(OCH3)3 -(CH2)3-Si(OCH3)3 -(CH2)2-Si(OCH2CH3)3 -(CH2)3-Si(OCH2CH3)3

[0105] Examples of such component (F) include the following compounds: where Me represents a methyl group and Et represents an ethyl group.

[0106] [ka] (In the formula, l″ is a number from 1 to 10.)

[0107] [ka] (In the formula, m″ is a number from 1 to 50.)

[0108] [ka] (wherein n'' is a number from 1 to 10.) [ka] (wherein o'' is a number from 1 to 50.)

[0109] [ka] (In the formula, p'' is a number from 1 to 10.)

[0110] [ka] (wherein q'' is a number from 1 to 50.)

[0111] [ka] (wherein r'' is a number from 1 to 10.)

[0112] [ka] (In the formula, s'' is a number from 1 to 50.)

[0113] This component (F) may be used alone or in combination of two or more. When component (F) is used, its amount is in the range of 0.01 to 20 parts by mass, preferably 0.01 to 10 parts by mass, and more preferably 0.01 to 8 parts by mass, per 100 parts by mass of component (A). A component (F) amount of 0.01 part by mass or more provides sufficient adhesiveness, while a component (F) amount of 20 parts by mass or less is preferred because it provides good physical strength to the cured product.

[0114] [Other ingredients] In order to enhance its practical utility, the perfluoropolyether compound-containing curable composition may contain, as necessary, optional components other than the components (A) to (F), such as fillers other than component (D), plasticizers, viscosity modifiers, flexibility imparting agents, inorganic pigments such as titanium oxide, iron oxide, carbon black, and cobalt aluminate, heat resistance improvers such as titanium oxide, iron oxide, carbon black, cerium oxide, cerium hydroxide, zinc carbonate, magnesium carbonate, and manganese carbonate, thermal conductivity imparting agents such as alumina, boron nitride, silicon carbide, and metal powder, and conductivity imparting agents such as carbon black, silver powder, and conductive zinc oxide. The amounts of these additives may be arbitrarily determined as long as the object of the present invention is not impaired.

[0115] As the plasticizer, viscosity modifier, and flexibility-imparting agent, a non-reactive (non-functional) linear polyfluoro compound represented by the following general formulas (20) and (21), which does not have functional groups (alkenyl groups and hydrosilyl groups) involved in the hydrosilylation addition reaction in the molecule, and / or a polyfluoromonoalkenyl compound represented by the following general formula (22) can be used.

[0116] F-(CF2CF2CF2O) w -J (20) (In equation (20), J is C x F 2x+1 - (x is a number from 1 to 3), and w is a number from 1 to 500, preferably a number from 2 to 300.

[0117] J-{(OCF(CF3)CF2) y -(OCF2CF2) z -(OCF2)α}-OJ (21) (In formula (21), J is the same as above, y and z each represent a number from 0 to 300, preferably a number from 0 to 150, except when both y and z are 0. In addition, α represents a number from 1 to 300, preferably a number from 1 to 150. The repeating units may be bonded to each other randomly.)

[0118] Rf-(L)β-CH=CH2(22) In formula (22), Rf is a group represented by the following general formula (23), and L is -CH2-, -OCH2-, -CH2OCH2-, or -CO-NR 11 -M-, and β is 0 or 1. F-[CF(CF3)CF2O]γ-CδF2δ- (23) (In formula (23), γ is a number from 1 to 200, preferably a number from 1 to 150, and δ is a number from 1 to 3.) Each group represented by L is bonded to Rf at the left end and to a carbon atom at the right end. 11 is a hydrogen atom, a methyl group, a phenyl group, or an allyl group, and M is -CH2-, a group represented by the following structural formula (24) or a group represented by the following structural formula (25). [ka] (Dimethylphenylsilylene group shown at the o-, m-, or p-position, with the left end bonded to a nitrogen atom and the right end bonded to a carbon atom.) [ka] (The left end is bonded to a nitrogen atom, and the right end is bonded to a carbon atom.)

[0119] Specific examples of the linear polyfluoro compound represented by the above general formula (20) or (21) include the following. F-(CF2CF2CF2O) w' -CF2CF3 (W' is a number between 1 and 200.) CF3-{(OCF(CF3)CF2) y' -(OCF2)α '}-O-CF3 (y' is a number from 1 to 200, and α' is a number from 1 to 200. The repeating units may be bonded randomly.) CF3-{(OCF2CF2) z' -(OCF2)α '}-O-CF3 (z' is a number from 1 to 200, and α' is a number from 1 to 200. The repeating units may be bonded randomly to each other.)

[0120] The linear polyfluoro compounds represented by the above general formula (20) or (21) may be used singly or in combination of two or more kinds.

[0121] Specific examples of the polyfluoromonoalkenyl compound represented by the above general formula (22) include the following. [ka] (where γ' is a number between 1 and 200.)

[0122] The polyfluoromonoalkenyl compounds represented by the general formula (22) may be used singly or in combination of two or more kinds.

[0123] [Production method of composition and curing conditions of composition] The method for producing the perfluoropolyether compound-containing curable composition used as a sealing material in the fuel cell stack of the present invention is not particularly limited, and the composition can be produced by uniformly mixing the above-mentioned components using a known device such as a planetary mixer, a Ross mixer, a Hobart mixer, a kneader, a three-roll mill, etc. When mixing, all components may be mixed at once, or a mixture of multiple components may be mixed in advance and then other components may be sequentially mixed into the mixture. The perfluoropolyether compound-containing curable composition thus produced is preferably heated to 50 to 200°C to accelerate the reaction, and then cured to form a sealant for a fuel cell separator. The composition can be heated for 10 seconds to 30 minutes. Methods for disposing the sealing material on the separator include a method in which the composition is molded into a seal shape by compression molding, casting molding, injection molding, or the like, and then combined with the separator, and a method in which the separator substrate and the sealing material are integrated by dipping, coating, screen printing, insert molding, or the like.

[0124] [Use of primer] In the present invention, a primer may be used to improve adhesion to the sealing portions of the fuel cell stack, and for example, the primer disclosed in JP-A-2004-331704 can be used. [Example]

[0125] Components (A) to (G) used in the following examples and comparative examples are shown below.

[0126] In the formula, Rf 3 is a structure represented by the following formula: [ka]

[0127] Component (A) (A-1): Perfluoropolyether polymer represented by the following formula (a+b=90, alkenyl group content: 0.0120 mol / 100 g) [ka]

[0128] (A-2): Perfluoropolyether polymer represented by the following formula (a+b=90, alkenyl group content: 0.0120 mol / 100 g) [ka]

[0129] (A-3): Perfluoropolyether polymer represented by the following formula (a+b=90, alkenyl group content 0.0120 mol / 100 g) [ka]

[0130] (A-4): Perfluoropolyether polymer represented by the following formula (p+q=63, alkenyl group content 0.0330 mol / 100 g) [ka]

[0131] (A-5): Perfluoropolyether polymer represented by the following formula (a+b=35, alkenyl group content 0.0330 mol / 100 g) [ka]

[0132] (A-6): Alkenyl group-containing polymer represented by the following formula (alkenyl group content: 0.0325 mol / 100 g) [ka]

[0133] (B) Component (B-1): Compound represented by the following formula (SiH group content: 0.0050 mol / g) [ka]

[0134] (B-2): Compound represented by the following formula (SiH group content: 0.0050 mol / g) [ka]

[0135] (B-3): Compound represented by the following formula (SiH group content: 0.0043 mol / g) [ka]

[0136] (B-4): Compound represented by the following formula (SiH group content: 0.0069 mol / g) [ka]

[0137] (C) Component (C-1): Toluene solution of platinum-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass)

[0138] (D) Component (D-1): R-972 (manufactured by Nippon Aerosil Co., Ltd.) Fumed silica whose surface has been hydrophobized with dimethyldichlorosilane, BET specific surface area: approximately 130 m 2 / g)

[0139] (E) Component (E-1): 50% by mass toluene solution of 1-ethynyl-1-cyclohexanol

[0140] (F) Component (F-1): A compound represented by the following formula: [ka]

[0141] (G) Component (G-1): Denka Black (manufactured by Denka Co., Ltd., acetylene black)

[0142] In Examples 1 to 11 and Comparative Example 1, compositions were prepared as follows using the respective components in the amounts shown in Table 1. The compositions were then molded and cured according to the methods described below to produce cured products, which were then subjected to the following tests.

[0143] Preparation of compositions of Examples 1 to 11 and Comparative Example 1: First, components (A) and (D) were mixed in the amounts shown in Table 1 using a planetary mixer at 120°C for 1 hour. The mixture was cooled to room temperature and then subjected to a three-roll mill process. To 130 parts by mass of the resulting mixture, component (G) was added in the amount shown in Table 1 and mixed at room temperature for 10 minutes. Then, component (C) was added in the amount shown in Table 1 and mixed at room temperature for 10 minutes. Then, component (E) was added in the amount shown in Table 1 and mixed at room temperature for 10 minutes. Then, components (B) and (F) were added in the amounts shown in Table 1 and mixed at room temperature for 10 minutes to obtain a composition. Component (B) was added so that the molar ratio of SiH groups in component (B) to alkenyl groups in component (A) was 1.2.

[0144] Preparation of cured products of Examples 1 to 11 and Comparative Example 1: The composition was press-crosslinked (primary crosslinking) at 150°C for 10 minutes to form a rubber sheet with a thickness of 2.0 mm, and then oven-crosslinked (secondary crosslinking) at 200°C for 4 hours to produce a cured product.

[0145] <Hydrofluoric acid resistance test> No. 3 dumbbells (JIS K 6249) were punched out from the rubber sheet after secondary crosslinking to prepare test specimens. An immersion solution with a hydrogen fluoride concentration of 500 ppm (by mass) was prepared by adding 60% by mass of hydrofluoric acid to a sulfuric acid aqueous solution of pH 2. The test specimens were immersed in the immersion solution at 95°C for 168 hours. After the immersion test, the test specimens were thoroughly rinsed with pure water and dried at 120°C for 2 hours. The tensile strength (JIS K 6249) of the test specimens before and after the immersion test was measured. The percentage change (%) was calculated using the following formula and is listed in Table 1, along with the results of the tensile strength before and after the immersion test. Change rate (%) = [(tensile strength after immersion test) - (tensile strength before immersion test)] / (tensile strength before immersion test) × 100

[0146] [Table 1] [Explanation of symbols]

[0147] 100 fuel cell 101 Fastening members 102 End Plate 200 fuel cell 201 Separator 202 Membrane electrode assembly 10a Fuel gas diffusion layer 10b Oxidant gas diffusion layer 11a Fuel electrode catalyst layer 11b Oxidant electrode catalyst layer 12 Electrolyte membrane 20a Oxidant gas inlet 20b Oxidant gas outlet 21a Coolant inlet 21b Coolant outlet 22a Fuel gas outlet 22b Fuel gas inlet 23 Flow channel 30 Sealing material

Claims

1. A fuel cell stack formed by stacking a plurality of fuel cell cells, each of which is composed of a pair of separators sandwiching a membrane electrode assembly including a fuel electrode, an electrolyte membrane, and an oxidizer electrode, the material of the electrolyte membrane is a fluorine-based polymer having a sulfonic acid group, an aromatic polymer having a sulfonic acid group, or an aliphatic polymer having a sulfonic acid group, a sealant is disposed on the separator, and the sealant is a cured product of a perfluoropolyether compound-containing curable composition; The perfluoropolyether compound-containing curable composition is (A) a perfluoropolyether polymer having at least two alkenyl groups in one molecule; (B) a fluorine-modified organosilicon compound having two or more hydrogen atoms bonded to silicon atoms in one molecule; (C) a hydrosilylation reaction catalyst, and (D) Reinforcing filler and A fuel cell stack, wherein the component (A) is at least one perfluoropolyether compound selected from the group consisting of compounds represented by the following general formula (1) and (2): Rf-(ZWβ) 2 (1) Rf-(Q-(Y)δ-B) 2 (2) (In the formula, Rf is a divalent perfluoropolyether group; Z is independently a single bond or a divalent to octavalent organic group which may contain a nitrogen atom, an oxygen atom, a silicon atom, a phosphorus atom, or a sulfur atom and which may be substituted with a halogen; W is independently a monovalent organic group having an alkenyl group at its terminal; β is a number from 1 to 7; Q is independently a single bond or a divalent organic group; each δ is independently a number from 1 to 10; Y is independently a divalent organic group having an alkenyl group; and B is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom.)

2. The perfluoropolyether compound-containing curable composition comprises (A) Component: 100 parts by mass, Component (B): an amount such that the amount of silicon-bonded hydrogen atoms (SiH groups) in component (B) is 0.5 to 3 moles per mole of alkenyl groups contained in the composition; Component (C): 0.1 to 2,000 ppm by mass of platinum group metal atoms relative to the mass of component (A); (D) Component: 10 to 40 parts by mass, 2. The fuel cell stack according to claim 1, comprising:

3. 2. The fuel cell stack according to claim 1, wherein the perfluoropolyether compound-containing curable composition further contains (E) a hydrosilylation reaction inhibitor.

4. 2. The fuel cell stack according to claim 1, wherein the perfluoropolyether compound-containing curable composition further contains (F) an adhesion promoter, which is an organopolysiloxane having, in one molecule, a hydrogen atom directly bonded to a silicon atom (SiH group), a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group, and an epoxy group and / or a trialkoxysilyl group bonded to a silicon atom via a divalent hydrocarbon group which may contain an oxygen atom.

5. A fuel cell stack as described in claim 1, wherein the fuel electrode and the oxidizer electrode have a catalyst layer, and the ionomer material in the catalyst layer is a compound having a sulfone group, a compound having an imide group, a compound having a carboxy group, or a compound having a phosphonic group.

6. A fuel cell comprising the fuel cell stack according to any one of claims 1 to 5.

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