Photocurable resin composition

Abstract

The present invention provides a photocurable resin composition capable of forming a cured product that has excellent adhesiveness and allows for easy dimensional control of compression ratio, with almost no permanent compression set.　The photocurable resin composition according to the present invention contains components (A) to (C), and contains 50 parts by mass or more of component (B) per 100 parts by mass of component (A). Component (A): a monofunctional urethane (meth)acrylate oligomer having a hydrogenated polybutadiene skeleton. Component (B): a monofunctional (meth)acrylate monomer having a C5-10 linear alkyl group (excluding component (A)). Component (C): a photoradical polymerization initiator.

Description

Photocurable resin composition

[0001] The present invention relates to a photocurable resin composition having adhesive properties.

[0002] In recent years, fuel cells have been attracting attention as a new energy system for automobiles and homes. A fuel cell is a power generation device that generates electricity by chemically reacting hydrogen and oxygen. Furthermore, fuel cells are a clean, next-generation power generation device due to their high energy efficiency during power generation and the production of water by the reaction of hydrogen and oxygen. Fuel cells are classified into four types: polymer electrolyte fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, and solid oxide fuel cells. Among these, polymer electrolyte fuel cells have high power generation efficiency despite their relatively low operating temperature (around 80°C), and are therefore expected to be used as automotive power sources, home power generators, small power sources for electronic devices such as mobile phones, and emergency power sources. As a sealant for use in polymer electrolyte fuel cells, a photocurable resin composition (e.g., International Publication No. 2023 / 090088) has been disclosed that exhibits low compression set and provides a cured product with excellent sealing properties.

[0003] Gaskets that utilize the reaction force generated when compressed are used as a sealant between separators in polymer electrolyte fuel cells. However, sealing is only possible if the gasket is used within an appropriate compression ratio range. Therefore, high-precision dimensional control of the compression ratio and loss of reaction force due to compression set that occurs over long periods of use have been issues. Therefore, a new sealant concept that allows for dimensional control of the compression ratio and does not suffer from compression set was needed.

[0004] Therefore, an object of the present invention is to provide a photocurable resin composition that allows for easy dimensional control of the compression ratio, causes almost no permanent compression set, and can form a cured product with excellent adhesiveness.

[0005] As a result of extensive investigations to solve the above problems, the present inventors have found that the above problems can be solved by the following photocurable resin composition, and have thus completed the present invention.

[0006] The gist of the present invention will now be described.

[0007] One aspect of the present invention is [1] a photocurable resin composition comprising the following components (A) to (C), in which the component (B) is contained in an amount of 50 parts by mass or more per 100 parts by mass of the component (A): Component (A): a monofunctional urethane (meth)acrylate oligomer having a hydrogenated polybutadiene skeleton; Component (B): a monofunctional (meth)acrylate monomer having a linear alkyl group having 5 to 10 carbon atoms (excluding the component (A)); and Component (C): a photoradical polymerization initiator.

[0008] [2] In the photocurable resin composition described in [1] above, the component (B) is preferably a monofunctional acrylate monomer having a linear alkyl group having 5 to 10 carbon atoms.

[0009] [3] In the photocurable resin composition according to the above [1] or [2], the component (B) is preferably n-octyl (meth)acrylate.

[0010] [4] In the photocurable resin composition according to any one of [1] to [3] above, the content of the component (B) is preferably 55 parts by mass or more and 120 parts by mass or less per 100 parts by mass of the component (A).

[0011] [5] In the photocurable resin composition according to any one of the above [1] to [4], the component (C) is preferably an acylphosphine oxide-based photoradical polymerization initiator.

[0012] [6] The photocurable resin composition according to any one of the above [1] to [5] preferably further contains silica powder as component (D).

[0013] [7] In the photocurable resin composition according to the above [6], the component (D) is preferably silica powder whose surface has been subjected to a hydrophobic treatment.

[0014] [8] The photocurable resin composition according to any one of the above [1] to [7] preferably does not contain a plasticizer.

[0015] Another aspect of the present invention is [9] a cured product obtained by curing the photocurable resin composition according to any one of [1] to [8] above.

[0016] Another aspect of the present invention is

[10] a sealing agent comprising the photocurable resin composition according to any one of [1] to [8] above.

[0017] Another aspect of the present invention is

[11] a fuel cell comprising at least one sealing portion selected from the group consisting of a sealing portion between adjacent separators in a fuel cell, a sealing portion between a frame of the fuel cell and an electrolyte membrane, and a sealing portion between the frame of the fuel cell and an electrolyte membrane electrode assembly, wherein the at least one sealing portion comprises the cured product according to [9] above.

[0018] According to one embodiment of the present invention, there is provided a photocurable resin composition comprising the following components (A) to (C), with 50 parts by mass or more of component (B) per 100 parts by mass of component (A): Component (A): a monofunctional urethane (meth)acrylate oligomer having a hydrogenated polybutadiene skeleton; Component (B): a monofunctional (meth)acrylate monomer having a linear alkyl group having 5 to 10 carbon atoms (excluding component (A)); and Component (C): a photoradical polymerization initiator.

[0019] This configuration makes it possible to provide a photocurable resin composition that allows for easy dimensional control of the compression ratio, causes almost no permanent compression set, and can form a cured product with excellent adhesion.

[0020] In this specification, the photocurable resin composition having the above-described structure is also simply referred to as the "photocurable resin composition according to the present invention" or "photocurable resin composition." In addition, in this specification, the component (A) is also simply referred to as the "component (A) according to the present invention" or "component (A)." In addition, in this specification, the component (B) is also simply referred to as the "component (B) according to the present invention" or "component (B)." In addition, in this specification, the component (C) is also simply referred to as the "component (C) according to the present invention" or "component (C)."

[0021] Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims. Furthermore, the embodiments described in this specification can be arbitrarily combined to form other embodiments.

[0022] In this specification, "X to Y" means a range including the numerical values ​​(X and Y) written before and after it as the lower and upper limits, respectively, and means "at least X and at most Y." In addition, in this specification, "X and / or Y" means at least one of X and Y, and includes X alone, Y alone, and a combination of X and Y. In addition, in this specification, a compound having a (meth)acryloyl group refers to a (meth)acrylate. The (meth)acryloyl group may exist in the form of a (meth)acryloyloxy group. In addition, the term "(meth)acryloyl" includes both acryloyl and methacryloyl. Therefore, for example, the term "(meth)acryloyl group" refers to an acryloyl group (H ２ C=CH-C(=O)-) and methacryloyl groups (H ２ C=C(CH ３ )-C(=O)-). Similarly, the term "(meth)acrylate" includes both acrylate and methacrylate, the term "(meth)acryl" includes both acryl and methacryl, and the term "(meth)acrylamide" includes both acrylamide and methacrylamide.

[0023] Throughout this specification, unless otherwise specified, singular expressions should be understood to include the plural concept. Therefore, singular articles (e.g., "a," "an," "the," etc. in English) should be understood to include the plural concept, unless otherwise specified. Furthermore, terms used in this specification should be understood to be used in the sense commonly used in the art, unless otherwise specified. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification (including definitions) will prevail.

[0024] Unless otherwise specified, the operations and measurements of physical properties are carried out under the conditions of room temperature (20 to 25° C.) and relative humidity of 40 to 50% RH.

[0025] [Photocurable Resin Composition] <Component (A)> The component (A) used in the present invention is a monofunctional urethane (meth)acrylate oligomer having a hydrogenated polybutadiene skeleton. The component (A) is an oligomer having one (meth)acryloyl group and a hydrogenated polybutadiene skeleton and a urethane structure. The (meth)acryloyl group may be present in a side chain of the molecular chain or at the terminal of the molecular chain, but from the viewpoint of adhesiveness of the cured product, it is preferably present at the terminal of the molecular chain. By having the hydrogenated polybutadiene skeleton in the component (A), it is possible to obtain a cured product with excellent hydrogen gas barrier properties and water vapor barrier properties required for a sealant for fuel cells. Here, hydrogenation refers to the addition of hydrogen atoms, and is also referred to as hydrogenation or hydrogen addition. The hydrogenated polybutadiene skeleton can be obtained by adding hydrogen atoms to the double bond of polybutadiene. The polybutadiene before hydrogenation may have only 1,2-bonds, only 1,4-bonds, or a mixture of 1,2- and 1,4-bonds. Furthermore, unhydrogenated carbon-carbon double bonds may remain in a portion of the hydrogenated polybutadiene skeleton. From the viewpoint of hydrogen gas barrier property and water vapor barrier property, the content of unhydrogenated polybutadiene skeletons is preferably less than 20% by mass, more preferably 10% by mass or less, even more preferably 3% by mass or less, and most preferably 0% by mass, i.e., no unhydrogenated polybutadiene skeleton, relative to the total mass (100% by mass) of component (A). Furthermore, from the viewpoint of adhesiveness of the cured product when used as an encapsulating material, a hydrogenated polybutadiene structure in which the number of 1,2-bonds exceeds the number of 1,4-bonds is particularly preferred. Note that, although the main skeleton of component (A) in the present invention is a hydrogenated polybutadiene skeleton, the hydrogenated polybutadiene skeleton portion of component (A) may be copolymerized with other monomers, as long as the effects of the present invention are not impaired.

[0026] The urethane bond is preferably used as a linking group when introducing a (meth)acryloyl group into the terminal or side chain of a compound having a hydrogenated polybutadiene skeleton, which is the raw material for component (A). For example, when the raw material is a compound having one hydroxy group at the terminal or side chain of the hydrogenated polybutadiene skeleton (hydroxy group-containing compound), this compound is reacted with a diisocyanate compound having two isocyanate groups in the molecule at a molar ratio of n moles to the hydroxy group-containing compound of at least n+1 moles, thereby producing a hydrogenated polybutadiene compound having terminal isocyanate groups in which hydroxy groups are linked by urethane bonds as an intermediate. Further reacting this intermediate with a compound having one hydroxy group and one (meth)acryloyl group in the molecule in a molar ratio equal to the molar number of isocyanate groups at the terminal of the intermediate can synthesize an oligomer having one (meth)acryloyl group and a hydrogenated polybutadiene structure in the main skeleton.

[0027] Examples of the diisocyanate compound are not particularly limited, and include conventionally known compounds such as toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), naphthalene diisocyanate (NDI), etc. These diisocyanate compounds may be used alone or in combination of two or more.

[0028] Examples of the above-mentioned compound having one hydroxy group and one (meth)acryloyl group in the molecule are not particularly limited, and include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, neopentyl glycol mono(meth)acrylate, (poly)ethylene glycol mono(meth)acrylate, (poly)propylene glycol mono(meth)acrylate, etc. These compounds having one hydroxy group and one (meth)acryloyl group may be used alone or in combination of two or more.

[0029] The synthesis method for component (A) is not limited to the above method. For example, a starting material containing an isocyanate group may be used as part of a compound having a hydrogenated polybutadiene skeleton. In this case, a diol compound having two hydroxy groups in the molecule may be used instead of a diisocyanate compound having two isocyanate groups in the molecule. Furthermore, a compound having one isocyanate group and one (meth)acryloyl group in the molecule may be used instead of a compound having one hydroxy group and one (meth)acryloyl group in the molecule. The oligomer obtained by such a reaction may be used as component (A).

[0030] The weight-average molecular weight of component (A) is preferably in the range of 10,000 to 80,000, more preferably in the range of 20,000 to 60,000, and even more preferably in the range of 30,000 to 50,000. When the weight-average molecular weight of component (A) is 10,000 or more, the cured product of the curable resin composition of the present invention can exhibit appropriate adhesiveness. On the other hand, when the weight-average molecular weight of component (A) is 80,000 or less, the curable resin composition of the present invention can have appropriate workability when uncured. In this specification, the weight-average molecular weight refers to the weight-average molecular weight in terms of polystyrene measured by gel permeation chromatography.

[0031] The component (A) may be used alone or in combination of two or more. The component (A) may be either a commercially available product or a synthetic product.

[0032] <Component (B)> The component (B) of the present invention is a monofunctional (meth)acrylate monomer (excluding the above-mentioned component (A)) having a linear alkyl group having 5 to 10 carbon atoms. The content of the component (B) is 50 parts by mass or more per 100 parts by mass of the component (A). Here, the monofunctional (meth)acrylate monomer is an ester compound having one (meth)acryloyloxy group, i.e., a (meth)acrylic acid ester. From the viewpoint of photocurability, the component (B) is preferably an ester compound having one acryloyloxy group, i.e., a monofunctional acrylate monomer having a linear alkyl group having 5 to 10 carbon atoms. The alkyl group is a linear, unbranched carbon chain. By having the alkyl group have 5 to 10 carbon atoms, high adhesion of the cured product can be maintained.

[0033] The component (B) may be used alone or in combination of two or more. The component (B) may be either a commercially available product or a synthetic product.

[0034] Specific examples of the component (B) include n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, etc. Of these, from the viewpoint of further increasing the adhesiveness of the cured product, n-octyl (meth)acrylate and n-nonyl (meth)acrylate are more preferred, and n-octyl acrylate is even more preferred.

[0035] The lower limit of the content of the (B) component is 50 parts by mass or more, preferably 55 parts by mass or more, more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more, per 100 parts by mass of the (A) component. The upper limit of the content of the (B) component is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less, per 100 parts by mass of the (A) component. That is, the content of the (B) component is preferably 50 parts by mass or more and 120 parts by mass or less, more preferably 55 parts by mass or more and 100 parts by mass or less, more preferably 60 parts by mass or more and 90 parts by mass or less, and even more preferably 70 parts by mass or more and 90 parts by mass or less, per 100 parts by mass of the (A) component. By having the content of the (B) component be 50 parts by mass or more and / or 120 parts by mass or less, per 100 parts by mass of the (A) component, a photocurable resin composition having excellent adhesiveness of the cured product can be obtained. When two or more types of (A) component are used, the above content represents the total amount thereof. When two or more types of (B) component are used, the above content represents the total amount thereof.

[0036] <Component (C)> The photoradical polymerization initiator of the component (C) used in the present invention is not particularly limited as long as it is a compound that generates radicals upon irradiation with active energy rays. Here, active energy rays include all light in the broad sense, such as radiation such as α-rays and β-rays, electromagnetic waves such as γ-rays and X-rays, electron beams, ultraviolet rays with wavelengths of about 100 to 400 nm, and visible light with wavelengths of about 400 to 800 nm, with ultraviolet rays being preferred. Specific examples of component (C) include acetophenone-based photoradical polymerization initiators, benzoin-based photoradical polymerization initiators, benzophenone-based photoradical polymerization initiators, aminobenzophenone-based photoradical polymerization initiators, thioxanthone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, and titanocene-based photoradical polymerization initiators. Among these photoradical polymerization initiators, from the viewpoint of obtaining a photocurable resin composition that can be photocured in a short time by irradiation with active energy rays, acetophenone-based photoradical polymerization initiators and acylphosphine oxide-based photoradical polymerization initiators are preferred, and acylphosphine oxide-based photoradical polymerization initiators are more preferred. Component (C) may be used alone or in combination of two or more. Furthermore, component (C) may be either a commercially available product or a synthetic product.

[0037] Specific examples of the acetophenone-based photoradical polymerization initiator include, but are not limited to, diethoxyacetophenone, 1-phenyl-2-hydroxy-2-methylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer. Examples of commercially available acetophenone-based photoradical polymerization initiators include Omnirad (registered trademark, the same applies hereinafter) 184, Omnirad 1173, Omnirad 2959, Omnirad 127 (all manufactured by IGM Resins B.V.), ESACURE (registered trademark) KIP-150 (manufactured by IGM Resins B.V.), and the like.

[0038] Specific examples of the acylphosphine oxide-based photoradical polymerization initiator include, but are not limited to, bis(2,4,6-trimethylbenzoyl)phenyl-phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, etc. Commercially available examples of the acylphosphine oxide-based photoradical polymerization initiator include Omnirad TPO, Omnirad 819, Omnirad 819DW (all manufactured by IGM Resins B.V.), and DOUBLECURE (registered trademark) 1256 (manufactured by DOUBLE BOND CHEMICAL IND. Co., LTD.).

[0039] The content of component (C) is not particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 10 parts by mass, and even more preferably 0.5 to 5 parts by mass, per 100 parts by mass of component (A). By having the content of component (C) be 0.1 to 20 parts by mass per 100 parts by mass of component (A), a photocurable resin composition can be obtained that can form a cured product with even better adhesiveness. When two or more types of component (C) are used, the above content represents the total amount.

[0040] <Component (D)> The photocurable resin composition according to the present invention preferably further comprises silica powder as component (D). By including component (D), a photocurable resin composition capable of forming a cured product with even better adhesiveness can be obtained. Component (D) is preferably silica powder whose surface has been hydrophobized with organochlorosilane, dimethylsilicone, hexamethyldisilazane, or the like, and from the viewpoint of obtaining good adhesiveness of the cured product, silica powder treated with dimethylsilicone is more preferred.

[0041] The raw silica powder used for the silica powder treated with dimethylsilicone is not particularly limited, and examples thereof include crystalline silica powder, amorphous silica powder, natural silica powder, synthetic silica powder, etc. As the raw silica powder, it is particularly preferable to use wet-process synthetic silica powder or dry-process synthetic silica powder, and it is more preferable to use wet-process synthetic silica powder.

[0042] Wet synthetic silica powder is, for example, synthesized by the neutralization reaction of sodium silicate and mineral acid.Specifically, there are precipitated synthetic silica powder (precipitation silica powder) synthesized in an alkaline region, and gel synthetic silica powder synthesized in an acidic region, but precipitated synthetic silica powder is preferred from the viewpoint of adhesiveness of the cured product.As dry synthetic silica powder, for example, there is one (fumed silica powder) synthesized by burning silicon tetrachloride in oxygen and hydrogen flame.

[0043] Examples of commercially available dry synthetic silica powders include Aerosil (registered trademark, the same applies hereinafter) R974, R972, R972V, R972CF, R805, R812, R812S, R816, R8200, RY200, RX200, RY200S, and R202, both of which are manufactured by Nippon Aerosil Co., Ltd. Examples of precipitated silica powders include commercially available products such as Nipsil SS-50A, SS-50YC, and SS-50B, both of which are manufactured by Tosoh Silica Corporation.

[0044] The average particle size of component (D) is not particularly limited, but the lower limit is preferably 0.001 μm or more, more preferably 0.01 μm or more, and even more preferably 0.5 μm or more. The upper limit of the average particle size of component (D) is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. That is, the average particle size of component (D) is preferably 0.001 μm or more and 10 μm or less, more preferably 0.01 μm or more and 5 μm or less, and even more preferably 0.5 μm or more and 3 μm or less. By using component (D) having such an average particle size, a photocurable resin composition can be obtained that can form a cured product with even better adhesiveness. The average particle size of component (D) is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by laser diffraction scattering.

[0045] The content of component (D) is not particularly limited, but is preferably 1 part by mass or more and 80 parts by mass or less, more preferably 3 parts by mass or more and 60 parts by mass or less, and even more preferably 5 parts by mass or more and 45 parts by mass or less, relative to 100 parts by mass of component (A). By having the content of component (D) be 1 part by mass or more and 80 parts by mass or less, a photocurable resin composition can be obtained that can form a cured product with even better adhesiveness. Note that when two or more types of component (D) are used, the above content represents the total amount.

[0046] <Other Components> The photocurable resin composition of the present invention may contain appropriate amounts of other components, such as a (meth)acrylate monomer having one or more (meth)acryloyl groups per molecule (excluding the above-mentioned component (B)), an antifoaming agent, a rheology control agent, an antioxidant, etc., within the range that does not impair the properties. The addition of these other components can improve the workability and heat resistance of the photocurable resin composition.

[0047] The photocurable resin composition of the present invention may contain a (meth)acrylate monomer (excluding the above-mentioned component (B)) and / or a (meth)acrylamide monomer having one or more (meth)acryloyl groups per molecule. Specific examples include monofunctional, difunctional, trifunctional or higher functional (meth)acrylate monomers and (meth)acrylamide monomers. These monomers may be used alone or in combination of two or more. The molecular weight of these monomers is not particularly limited, but is, for example, less than 1,000. The content of (meth)acrylate monomers having one or more (meth)acryloyl groups in one molecule (excluding the above-mentioned (B) component) is preferably less than 50% by mass, more preferably less than 35% by mass, even more preferably less than 10% by mass, and most preferably 0% by mass, i.e., no (meth)acrylate monomers having one or more (meth)acryloyl groups in one molecule (excluding the above-mentioned (B) component) are contained. By having the content of (meth)acrylate monomers having one or more (meth)acryloyl groups in one molecule (excluding the above-mentioned (B) component) less than 50% by mass, the adhesiveness of the cured product can be further improved.

[0048] Specific examples of the monofunctional (meth)acrylate monomer other than component (B) include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octylheptyl (meth)acrylate, undecyl (meth)acrylate, behenyl (meth)acrylate, isodecyl (meth)acrylate, isononyl (meth)acrylate, stearyl (meth)acrylate, tridecyl (meth)acrylate, n-lauryl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, and octylheptyl (meth)acrylate. Aliphatic (meth)acrylates such as octadecyl (meth)acrylate, nonadecyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, and mono(2-(meth)acryloyloxyethyl)succinate; alicyclic (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, mono(2-(meth)acryloyloxyethyl)tetrahydrophthalate, and mono(2-(meth)acryloyloxyethyl)hexahydrophthalate;Benzyl (meth)acrylate, phenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, 1-naphthoxyethyl (meth)acrylate, 2-naphthoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate p) Aromatic (meth)acrylates such as acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate, and 2-hydroxy-3-(2-naphthoxy)propyl (meth)acrylate Acrylates: heterocyclic (meth)acrylates such as 2-tetrahydrofurfuryl (meth)acrylate, N-(meth)acryloyloxyethylhexahydrophthalimide, 2-(meth)acryloyloxyethyl-N-carbazole, caprolactone-modified products thereof, ω-carboxy-polycaprolactone mono(meth)acrylate, glycidyl (meth)acrylate, α-ethylglycidyl (meth)acrylate, α-propylglycidyl (meth)acrylate, α- compounds having an ethylenically unsaturated group and an epoxy group, such as butyl glycidyl (meth)acrylate, 2-methyl glycidyl (meth)acrylate, 2-ethyl glycidyl (meth)acrylate, 2-propyl glycidyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 3,4-epoxyheptyl (meth)acrylate, α-ethyl-6,7-epoxyheptyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate;Ethylenically unsaturated groups and oxetanyl such as (2-ethyl-2-oxetanyl)methyl (meth)acrylate, (2-methyl-2-oxetanyl)methyl (meth)acrylate, 2-(2-ethyl-2-oxetanyl)ethyl (meth)acrylate, 2-(2-methyl-2-oxetanyl)ethyl (meth)acrylate, 3-(2-ethyl-2-oxetanyl)propyl (meth)acrylate, and 3-(2-methyl-2-oxetanyl)propyl (meth)acrylate compounds having an ethylenically unsaturated group and an isocyanate group, such as 2-(meth)acryloxyethyl isocyanate; and compounds having an ethylenically unsaturated group and a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. These monofunctional (meth)acrylate monomers may be used alone or in combination of two or more;

[0049] Specific examples of the bifunctional (meth)acrylate monomer include 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethylene oxide-modified neopentyl glycol di( Examples of the difunctional (meth)acrylate include, but are not limited to, di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, epichlorohydrin-modified bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol S di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, dicyclopentenyl di(meth)acrylate, ethylene oxide-modified dicyclopentenyl di(meth)acrylate, and di(meth)acryloyl isocyanurate. These bifunctional (meth)acrylate monomers may be used alone or in combination of two or more.

[0050] Specific examples of the tri- or higher functional (meth)acrylate monomer include, but are not limited to, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethylene oxide (EO)-modified trimethylolpropane tri(meth)acrylate, propylene oxide (PO)-modified trimethylolpropane tri(meth)acrylate, epichlorohydrin (ECH)-modified trimethylolpropane tri(meth)acrylate, ECH-modified glycerol tri(meth)acrylate, tris((meth)acryloyloxyethyl)isocyanurate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, alkyl-modified dipentaerythritol pentaacrylate, and dipentaerythritol hexa(meth)acrylate. These tri- or higher functional (meth)acrylate monomers may be used singly or in combination of two or more.

[0051] Specific examples of the (meth)acrylamide monomer include, but are not limited to, (meth)acryloylmorpholine, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, etc. These (meth)acrylamide monomers may be used alone or in combination of two or more.

[0052] Specific examples of the antifoaming agent include silica-based compounds, amide-based compounds, silicone-based (including polysiloxane-based) compounds, and paraffin-based mineral oils.

[0053] The rheology control agent generally refers to an additive that controls the rheological properties of a composition when added to the composition, and specific examples include those called thixotropic agents, anti-settling agents, anti-sagging agents, thickeners, etc. More specific examples of the rheology control agent include inorganic rheology control agents such as amorphous silicon dioxide, montmorillonite, bentonite, colloidal alumina, etc.; polyolefin rheology control agents such as polyethylene and polypropylene, cellulose rheology control agents such as nitrocellulose, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, etc.; alginic acid rheology control agents such as sodium alginate, protein rheology control agents such as casein, sodium caseinate, ammonium caseinate, etc.; polyvinyl alcohol, polyvinylpyrrolidone, etc. Examples of the rheology control agent include polyvinyl rheology control agents such as those listed above; polyacrylic acid rheology control agents such as sodium polyacrylate; polyether rheology control agents such as polyether dialkyl esters and polyether dialkyl ethers; urea rheology control agents obtained by reacting an isocyanate group-containing compound such as methyl isocyanate, ethyl isocyanate, ethylene diisocyanate, or hexamethylene diisocyanate with an amino group-containing compound such as ethylamine, propylamine, ethylene diamine, or hexamethylene diamine; and polycarboxylic acid rheology control agents such as polyhydroxycarboxylic acid amides. From the viewpoints of improving the workability of the photocurable resin composition of the present invention and preventing a decrease in the adhesiveness of the cured product, the amount of the rheology control agent blended is preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 3% by mass or less, based on the total mass of the photocurable resin composition being 100% by mass.

[0054] Examples of the antioxidant that can be used include phenolic antioxidants, hindered phenolic antioxidants, organic sulfur antioxidants, amine antioxidants, and benzotriazole antioxidants. Among these, from the viewpoint of not reducing the visible light curability and acidic aqueous solution resistance, phenolic antioxidants are preferred, and dibutylhydroxytoluene (2,6-di-tert-butyl-p-cresol, BHT) is more preferred. From the viewpoint of not reducing the hot water resistance of the photocurable resin composition of the present invention, the content of the antioxidant is preferably from 0.001% to 3% by mass, and more preferably from 0.01% to 2% by mass, based on the total mass of the photocurable resin composition being 100% by mass.

[0055] The photocurable resin composition of the present invention preferably contains substantially no plasticizer. If a plasticizer is contained, the adhesiveness of the cured product of the photocurable resin composition may decrease. Here, "substantially no plasticizer" refers to a content of 5% by mass or less, where the total mass of the photocurable resin composition is 100% by mass. The plasticizer content is more preferably 3% by mass or less, and most preferably 0% by mass, i.e., no plasticizer is contained, where the total mass of the photocurable resin composition is 100% by mass. Specific examples of plasticizers include phthalate ester-based plasticizers, adipate ester-based plasticizers, trimellitate ester-based plasticizers, polyester-based plasticizers, epoxidized vegetable oil-based plasticizers, and poly-α-olefin-based plasticizers. In particular, from the viewpoint of not decreasing the adhesiveness of the cured product of the photocurable resin composition, it is more preferable that the photocurable resin composition of the present invention does not contain a poly-α-olefin-based plasticizer. The poly-α-olefin plasticizer is not particularly limited, but examples thereof include plasticizers produced by polymerization and hydrogenation using ethylene-derived α-olefins as raw materials. Commercially available examples of the poly-α-olefin plasticizer include the "SpectraSyn series" (manufactured by ExxonMobil).

[0056] The photocurable resin composition of the present invention can be produced by a conventionally known method. For example, it can be produced by blending predetermined amounts of components (A) to (C), as well as component (D) and other components, which are added as needed, and mixing them using a mixing means such as a mixer (e.g., a planetary mixer). The temperature during mixing is preferably 10 to 70°C, and the mixing time is preferably 0.1 to 5 hours. The photocurable resin composition of the present invention is also preferably produced in a light-shielded environment.

[0057] <Coating Method> As a method for applying the curable resin composition of the present invention to an adherend, a known coating method for resin compositions can be appropriately adopted, such as dispensing using an automatic coater, spraying, inkjet printing, screen printing, gravure printing, dipping, spin coating, etc.

[0058] <Curing Method> The photocurable resin composition of the present invention can be cured by irradiating it with active energy rays such as ultraviolet rays and visible light. The active energy ray source used in this case is not particularly limited, and examples thereof include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, a sodium lamp, a halogen lamp, a xenon lamp, an LED, a fluorescent lamp, sunlight, and an electron beam irradiation device. The irradiation dose (cumulative light amount) of the active energy ray is set to 10 kJ / m or less from the viewpoint of the properties of the cured product. ２ It is preferable that the concentration is 20 kJ / m or more. ２ From the viewpoint of the takt time of the curing step, the irradiation amount (integral light amount) of the active energy ray is more preferably 70 kJ / m or more. ２ Preferably, it is 60 kJ / m or less. ２ More preferably, it is 50 kJ / m or less. ２ It is even more preferable that:

[0059] <Adherend> The adherend on which the photocurable resin composition of the present invention is used is not particularly limited, and examples thereof include metal-metal, metal and plastic, metal and rubber, metal and glass, plastic and rubber, plastic and glass, plastic-plastic, rubber-rubber, rubber-glass, and glass-glass. Examples of metals include, but are not particularly limited to, gold, silver, iron, aluminum, magnesium, copper, stainless steel, and titanium. Examples of plastics include, but are not particularly limited to, fiber-reinforced plastic (FRP), carbon fiber-reinforced plastic (CFRP), polyacrylic resin, polyester, polyamide, acrylonitrile-butadiene-styrene (ABS) resin, polyamide 6, polycarbonate, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyphenylene ether, polyether ether ketone, polyethylene, polypropylene, and polyethylene naphthalate (PET). The rubber is not particularly limited, but examples thereof include nitrile rubber, butyl rubber, urethane rubber, silicone rubber, ethylene propylene diene rubber (EPDM), etc. In order to bond members together using the photocurable resin composition of the present invention or a cured product thereof, it is preferable that the members are light-transmitting.

[0060] <Applications> The photocurable resin composition of the present invention can be used in fuel cells, solar cells, dye-sensitized solar cells, lithium ion batteries, electrolytic capacitors, liquid crystal displays, organic EL displays, electronic paper, LEDs, hard disk drives, photodiodes, optical communications / circuits, electric wires / cables / optical fibers, optical isolators, laminates such as IC cards, sensors, substrates, pharmaceutical / medical instruments / devices, etc. Among these, the photocurable resin composition of the present invention is particularly preferably used for fuel cells because of the excellent adhesiveness of the cured product.

[0061] The fuel cell according to the present invention is characterized by being sealed with the photocurable resin composition of the present invention and / or a cured product thereof. Components that require sealing in a fuel cell include a separator, a frame, a polymer electrolyte membrane, an anode, an air electrode, a membrane electrode assembly (MEA), and the like, and a seal portion can be formed between these components. More specific sealed locations (where a seal portion is formed) include between adjacent separators, between a separator and a frame, and between a frame and a polymer electrolyte membrane or an MEA. The photocurable resin composition or the sealant of the present invention can be cured by irradiating it with active energy rays such as light to obtain a cured product. The photocurable resin composition or sealant of the present invention, or a cured product thereof, can be used as a seal portion around components such as a separator, a frame, a polymer electrolyte membrane, an anode, an air electrode, or a membrane electrode assembly for a fuel cell. The photocurable resin composition or sealant, or a cured product thereof, of the present invention can be suitably used for at least one sealing portion selected from the group consisting of a sealing portion between adjacent separators in a fuel cell, a sealing portion between a fuel cell frame and a polymer electrolyte membrane, and a sealing portion between a fuel cell frame and a membrane electrode assembly. The main purpose of the sealing "between the separator and the frame" or "between the polymer electrolyte membrane or MEA and the frame" is to prevent gas mixing and leakage, and the purpose of the sealing between adjacent separators is to prevent gas leakage and leakage of cooling water from the cooling water flow paths to the outside.

[0062] <Sealing Method> The photocurable resin composition of the present invention can be suitably used as a sealant. The sealant is applied to gaps between one adherend or two or more adherends to keep the inside airtight, thereby preventing leakage and preventing the intrusion of moisture from the outside, thereby providing a so-called seal.

[0063] When the photocurable resin composition of the present invention is used as a sealant, it is preferably liquid at 25° C., and more preferably has a viscosity of 1 to 100 Pa·s at 25° C. Sealing methods using the photocurable resin composition of the present invention are not particularly limited, but examples include FIPG (formed-in-place gasket), CIPG (cured-in-place gasket), MIPG (molded-in-place gasket), etc.

[0064] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0065] Examples 1 to 6, Comparative Examples 1 to 4 The following components were prepared to prepare photocurable resin compositions.

[0066] <Component (A) and Comparative Components> (A-1): Hydrogenated polybutadiene monofunctional urethane acrylate oligomer, number of (meth)acryloyl functional groups: 1, weight average molecular weight: 40,000 (A'-1): Hydrogenated polybutadiene bifunctional urethane acrylate oligomer, number of (meth)acryloyl functional groups: 2, weight average molecular weight: 3,800, trade name: TEAI-1000 (manufactured by Nippon Soda Co., Ltd.) <Component (B) and Comparative Components> (B-1): n-octyl acrylate (number of alkyl group carbon atoms: 8), trade name: NOAA (manufactured by Osaka Organic Chemical Industry Ltd.) (B'-1): n-lauryl acrylate (number of alkyl group carbon atoms: 12), trade name: L-A (manufactured by Osaka Organic Chemical Industry Ltd.) (B'-2): Isobornyl acrylate, trade name: Light Acrylate IBX-A (manufactured by Kyoeisha Chemical Co., Ltd.) (B'-3): Isononyl acrylate (number of alkyl group carbon atoms: 9) Trade name: INAA (manufactured by Osaka Organic Chemical Industry Ltd.) <Component (C)> (C-1): 2,4,6-trimethylbenzoyl-diphenylphosphine oxide Trade name: Omnirad TPO (manufactured by IGM Resins B.V.) <Component (D)> (D-1): Hydrophobic silica powder surface-treated with dimethyl silicone (precipitated synthetic silica powder, average particle size: 2.9 μm, spherical) Trade name: Nipsil SS50A (manufactured by Tosoh Silica Corporation) (D-2): Hydrophobic silica powder surface-treated with dimethyl silicone (dry-process synthetic silica powder, average particle size: 0.012 μm, spherical) Trade name: Aerosil RY200 (manufactured by Nippon Aerosil Co., Ltd.) (Others) Antioxidant (dibutylhydroxytoluene, BHT) reagent.

[0067] The photocurable resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were prepared by the following method. That is, component (B) and component (C) were weighed into a stirring vessel in the dark and stirred at 40 to 60°C for 1 hour. Thereafter, the remaining components were weighed into a stirring vessel and stirred for an additional 30 minutes in the dark to obtain a photocurable resin composition. The content (amount blended) of each component is shown in Table 1 below. Note that all contents (amount blended) in Table 1 below are expressed in parts by mass, and blank spaces indicate that the component was not used.

[0068]

[0069] The photocurable resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to an adhesion test.

[0070] [Adhesion Test] The compositions obtained in the above Examples and Comparative Examples were each squeegeeed onto an untreated transparent PET film using a glass plate to have dimensions of 10 mm width × 100 mm length × 1 mm thickness, and the cumulative light intensity was 40 kJ / m ２ The cured product was cured by irradiating it with ultraviolet light (wavelength 365 nm) until the temperature reached a certain value. Next, a SUS304 test piece measuring 25 mm wide x 100 mm long x 1.6 mm thick was attached to the cured product, and the test piece was pressed by rolling it back and forth five times with a 5 kg roller to prepare a test specimen. The 180° peel strength was measured using the resulting test piece. The peel strength was determined by measuring the average peel load excluding the initial and final peel lengths in accordance with JIS Z0237:2009, Test Methods for Pressure-Sensitive Adhesive Tapes and Pressure-Sensitive Adhesive Sheets, using a Tensilon at 25°C. The results are shown in Table 1 above. The pulling speed was 500 mm / min. The adhesive strength evaluation criteria are as follows, with an A rating indicating practical use: Evaluation Criteria A: 0.6 N / mm or more B: Less than 0.6 N / mm

[0071] As is clear from Table 1 above, by using the photocurable resin compositions of Examples 1 to 6 containing components (A) to (C), sealants with excellent adhesive properties were obtained. On the other hand, Comparative Example 1, in which component (A'-1), which is outside the scope of the present invention, was used instead of component (A), resulted in poor adhesive properties for the cured product. Furthermore, Comparative Examples 2 to 4, in which the content of component (B) was less than 50 parts by mass per 100 parts by mass of component (A), also resulted in poor adhesive properties for the cured product. From these results, it can be seen that by combining predetermined amounts of components (A) to (C), a photocurable resin composition with excellent adhesive properties for the cured product can be obtained.

[0072] The photocurable resin composition of the present invention can form a cured product having excellent adhesiveness, and therefore can be suitably used for various sealing applications. In particular, the photocurable resin composition of the present invention is industrially useful because it is effective as a curable sealant for fuel cells.

[0073] This application is based on Japanese Patent Application No. 2024-111906, filed on July 11, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

Claims

1. A photocurable resin composition comprising the following components (A) to (C), with 50 parts by mass or more of component (B) per 100 parts by mass of component (A): Component (A): a monofunctional urethane (meth)acrylate oligomer having a hydrogenated polybutadiene skeleton; Component (B): a monofunctional (meth)acrylate monomer having a linear alkyl group having 5 to 10 carbon atoms (excluding component (A)); and Component (C): a photoradical polymerization initiator.

2. The photocurable resin composition according to claim 1, wherein component (B) is a monofunctional acrylate monomer having a linear alkyl group having 5 to 10 carbon atoms.

3. The photocurable resin composition according to claim 1, wherein the component (B) is n-octyl (meth)acrylate.

4. A photocurable resin composition according to claim 1 or 2, wherein the content of the component (B) is 55 parts by mass or more and 120 parts by mass or less per 100 parts by mass of the component (A).

5. The photocurable resin composition according to claim 1 or 2, wherein component (C) is an acylphosphine oxide-based photoradical polymerization initiator.

6. The photocurable resin composition according to claim 1 or 2, further comprising silica powder as component (D).

7. The photocurable resin composition according to claim 6, wherein component (D) is silica powder whose surface has been subjected to a hydrophobic treatment.

8. The photocurable resin composition according to claim 1 or 2, which does not contain a plasticizer.

9. A cured product obtained by curing the photocurable resin composition according to claim 1 or 2.

10. A sealant comprising the photocurable resin composition according to claim 1 or 2.

11. A fuel cell comprising at least one sealing portion selected from the group consisting of a sealing portion between adjacent separators in a fuel cell, a sealing portion between a fuel cell frame and a polymer electrolyte membrane, and a sealing portion between a fuel cell frame and an electrolyte membrane electrode assembly, wherein the at least one sealing portion comprises the cured product according to claim 9.

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