Photocurable resin composition

Abstract

To provide a photocurable resin composition excellent in hot water resistance for realizing a sealing agent of a fuel cell satisfying the requirement of hot water resistance while maintaining compression set.SOLUTION: A photocurable resin composition comprising the following components (A) to (D): (B) a monofunctional (meth) acrylate monomer having an alkyl group (excluding the monomer (A)), (C) a polycarbodiimide having a hydrophilic group, and (D) a photoradical polymerization initiator CH3 CH2C SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable resin composition having resistance to hot water. [Background technology]

[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 because they have high energy efficiency during power generation and produce water through the reaction of hydrogen and oxygen. There are four types of fuel cells: 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. A photocurable resin composition (Patent Document 1) has been disclosed as a sealant for use in polymer electrolyte fuel cells, which has low compression set and produces a cured product with excellent sealing properties. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2023 / 090088 publication Summary of the Invention [Problem to be solved by the invention]

[0004] The sealant between separators used in polymer electrolyte fuel cells must be highly reliable against water to prevent any abnormalities during long-term operation of the fuel cell, and in recent years the required temperature for water resistance has shifted from below 100°C to a higher temperature of 120°C. However, it has been difficult to meet the requirement for hot water resistance while maintaining compression set, an important characteristic of fuel cell sealants. [Means for solving the problem]

[0005] As a result of extensive research conducted by the present inventors to achieve the above object, they have completed a photocurable resin composition that is excellent in resistance to hot water.

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

[0007] [1] A photocurable resin composition comprising the following components (A) to (D): Component (A): Polyisobutylene resin containing one or more (meth)acryloyl groups and a -[CH2C(CH3)2]- unit Component (B): Monofunctional (meth)acrylate monomer having an alkyl group (excluding component (A)) Component (C): Polycarbodiimide having hydrophilic groups Component (D): Photoradical polymerization initiator

[0008] [2] The photocurable resin composition according to [1], wherein the component (B) is an acrylate monomer.

[0009] [3] The photocurable resin composition according to [1], wherein the component (B) has a linear alkyl group having 5 to 12 carbon atoms.

[0010] [4] The photocurable resin composition according to any one of [1] and [2], wherein the content of the component (C) is 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

[0011] [5] The photocurable resin composition according to any one of [1] and [2], wherein the component (D) is an acylphosphine oxide-based photoradical polymerization initiator.

[0012] [6] The photocurable resin composition according to any one of [1] and [2], further comprising silica powder as component (E).

[0013] [7] The photocurable resin composition according to [6], wherein the component (E) is a hydrophobically treated silica powder.

[0014] [8] The photocurable resin composition according to any one of [1] and [2], which does not contain any (meth)acrylate monomer having one or more (meth)acryloyl groups in one molecule other than the components (A) and (B).

[0015] [9] A cured product obtained by curing the photocurable resin composition according to any one of [1] and [2]. [Effects of the Invention]

[0016] The present invention provides a photocurable resin composition that has excellent high-temperature water resistance. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments. In this specification, "X to Y" means a range including the numerical values ​​(X and Y) before and after it as the lower and upper limits, respectively, and means "X or more and Y or less." In the present invention, a compound having a (meth)acryloyl group refers to a (meth)acrylate. The (meth)acryloyl group may have a (meth)acryloyl group in the form of a (meth)acryloyloxy group. Furthermore, the term "(meth)acryloyl" encompasses both acryloyl and methacryloyl. Thus, for example, the term "(meth)acryloyl group" encompasses both an acryloyl group (HC=CH-C(=O)-) and a methacryloyl group (HC=C(CH)-C(=O)-). Similarly, the term "(meth)acrylate" includes both acrylate and methacrylate, the term "(meth)acrylic" includes both acrylic and methacrylic, and the term "(meth)acrylamide" includes both acrylamide and methacrylamide.

[0018] The component (A) used in the present invention is not particularly limited as long as it is a polyisobutylene resin (a polymer having a polyisobutylene skeleton) that has one or more (meth)acryloyl groups and contains -[CHC(CH)]- units. Component (A) may be, for example, a polymer that contains a (meth)acryloyl group (CH=CH-C(=O)- or CH=C(CH)-C(=O)-) and -[CHC(CH)]- units (sometimes referred to herein as "polyisobutylene units"). It is also suitable for component (A) to contain -[CHC(CH)]- units in an amount of, for example, 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, of the total amount of the structural units (component (A)). Furthermore, the component (A) suitably contains -[CH2C(CH3)2]- units in an amount of, for example, less than 100% by mass, in another embodiment, 95% by mass or less, and in yet another embodiment, 90% by mass or less, based on the total amount of structural units (component (A)). The component (A) suitably contains, per molecule, preferably 1 to 12, more preferably 2 to 8, even more preferably 2 to 4, and particularly preferably 2 (meth)acryloyl groups. In the present invention, the term "polymer" can be defined, without being bound by the following theory, as a compound having a structure in which a repeating unit of a monomer is attached to the polymer main chain, and consisting of 50 or more, preferably 100 or more repeating units. The number of -[CH2C(CH3)2]- units in one polyisobutylene skeleton is, for example, 50 or more, preferably 60 to 300, and more preferably 80 to 200. The (meth)acryloyl group may be present in either a side chain and / or at the end of the molecule, but is preferably present at the end of the molecule from the viewpoint of obtaining a photocurable resin composition that gives a cured product with low compression set and excellent sealing properties during compression.

[0019] Specific examples of the component (A) include polyisobutylene polymers having (meth)acryloyloxyalkoxyphenyl groups. The main skeleton of the component (A) in the present invention is a polyisobutylene skeleton. While isobutylene is primarily used as the monomer constituting this polyisobutylene skeleton, other monomers may be copolymerized within a range that does not impair the effects of the present invention. For ease of use, the component (A) is preferably liquid at room temperature (25°C). Because of its polyisobutylene skeleton, the component (A) is characterized by low moisture permeability. The component (A) may be a diblock or triblock with other blocks, but a monoblock is most preferred. When the (meth)acryloyl group in the component (A) is a (meth)acryloyloxy group, the component (A) contains two or more (meth)acryloyloxy groups in the compound. From the viewpoint of curability, the component (A) preferably contains two (meth)acryloyloxy groups. There are no particular limitations on the method for producing component (A), and component (A) can be produced by the methods described in JP 2013-35901 A, WO 2013 / 047314, WO 2017 / 099043, etc.

[0020] Specific examples of the component (A) include EP400V in the EPION (registered trademark) series manufactured by Kaneka Corporation, but are not limited thereto.

[0021] The component (B) of the present invention is a monofunctional (meth)acrylate monomer having an alkyl group (excluding the component (A)). The monofunctional (meth)acrylate monomer is an ester compound having one (meth)acryloyloxy group, i.e., a (meth)acrylic acid ester, and from the viewpoint of photocurability, an ester compound having one acryloyloxy group, i.e., an acrylic acid ester (a monofunctional acrylate monomer having an alkyl group), is preferred. The alkyl group may be a linear or branched alkyl group, but from the viewpoint of excellent hot water resistance, a linear alkyl group is preferred. From the same viewpoint, the alkyl group preferably has 5 to 12 carbon atoms, more preferably 6 to 11, and even more preferably 7 to 9 carbon atoms.

[0022] The component (B) is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, pentyl (meth)acrylate (C5), hexyl (meth)acrylate (C6), heptyl (meth)acrylate (C7), octyl (meth)acrylate (C8), nonyl (meth)acrylate (C9), decyl (meth)acrylate (C10), undecyl (meth)acrylate (C11), lauryl (meth)acrylate (C12), octylheptyl (meth)acrylate, behenyl (meth)acrylate, isodecyl (meth)acrylate, and isononyl (meth)acrylate. Among these, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, and n-lauryl (meth)acrylate are preferred from the viewpoint of high-temperature water resistance, and n-heptyl acrylate, n-octyl acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, and n-lauryl (meth)acrylate are particularly preferred, and n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-undecyl acrylate, and n-lauryl acrylate are particularly preferred.

[0023] The amount of the (B) component blended is preferably 10 to 90 parts by mass, more preferably 30 to 80 parts by mass, and most preferably 50 to 70 parts by mass, per 100 parts by mass of the (A) component. When multiple types of (A) components are used, it is preferable that the total amount thereof satisfies the above relationship. Similarly, when multiple types of (B) components are used, it is preferable that the total amount thereof satisfies the above relationship. By using an amount of 10 to 90 parts by mass, a photocurable resin composition with excellent hot water resistance can be obtained.

[0024] Component (C) of the present invention is a polycarbodiimide having a hydrophilic group. A polycarbodiimide refers to a compound having two or more carbodiimide groups represented by "-N=C=N-." In the present invention, since components (A) and (B) are substantially free of carboxyl groups and phenolic groups, the polycarbodiimide does not function as a crosslinking agent. That is, in the cured product obtained by curing the photocurable resin composition of the present invention, the polycarbodiimide exists without forming a crosslinked structure. This is thought to improve the hot water resistance of the photocurable resin composition by preventing the carbodiimide group from reacting with the carboxylic acid generated upon hydrolysis of the ester bond in the cured product, thereby preventing the carboxylic acid from promoting hydrolysis, but this is not necessarily the case. The hydrophilic group refers to an atomic group that exhibits affinity for water due to weak bonds with water molecules such as electrostatic interactions and hydrogen bonds. It is thought that the inclusion of a hydrophilic group facilitates the action of the carboxylic acid generated upon hydrolysis of the ester bond in the cured product, but this is not necessarily the case. Examples of the hydrophilic group include polar groups such as a hydroxyl group, a carboxyl group, an amino group, a carbonyl group, an acyl group, a sulfo group, and a thiol group, as well as an ether bond, and from the viewpoint of resistance to hot water, it is preferable to have an ether group. Note that an isocyanate group is not considered to be a hydrophilic group.

[0025] The polycarbodiimide can be obtained, for example, by subjecting an isocyanate compound such as a monoisocyanate or a diisocyanate to a carbodiimidation reaction in the presence of a carbodiimidation catalyst (such as a phospholene). The polycarbodiimide may or may not have an isocyanate group, but from the viewpoint of hot water resistance, it is preferable that the polycarbodiimide does not have an isocyanate group.

[0026] The amount of the (C) component blended is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and most preferably 0.8 to 4 parts by mass, per 100 parts by mass of the (A) component. When multiple types of (A) components are used, it is preferable that the total amount thereof satisfies the above relationship. Similarly, when multiple types of (C) components are used, it is preferable that the total amount thereof satisfies the above relationship. By using an amount of 0.1 to 10 parts by mass, a photocurable resin composition with excellent hot water resistance can be obtained.

[0027] The photoradical polymerization initiator (D) used in the present invention is not limited as long as it 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. Examples of component (D) 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, acetophenone-based photoradical polymerization initiators and acylphosphine oxide-based photoradical polymerization initiators are preferred, with acylphosphine oxide-based photoradical polymerization initiators being particularly preferred, from the viewpoint of obtaining a photocurable resin composition that can be photocured in a short time upon irradiation with active energy rays. These may be used alone or in combination of two or more.

[0028] Examples of acetophenone-based photoradical polymerization initiators 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. Commercially available acetophenone-based photoradical polymerization initiators include Omnirad (registered trademark, the same applies hereinafter) 184, Omnirad 1173, Omnirad 2959, Omnirad 127 (manufactured by IGM Resins BV), and ESACURE (registered trademark) KIP-150 (manufactured by IGM Resins BV).

[0029] Examples of acylphosphine oxide-based photoradical polymerization initiators include, but are not limited to, bis(2,4,6-trimethylbenzoyl)phenyl-phosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, etc. Commercially available acylphosphine oxide-based photoradical polymerization initiators include OmniradTPO, Omnirad819, Omnirad819DW (manufactured by IGM Resins BV), and DOUBLECURE (registered trademark) 1256 (manufactured by DOUBLE BOND CHEMICAL IND. Co., LTD).

[0030] The amount of component (D) blended is not particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 10 parts by mass, and particularly preferably 0.5 to 5 parts by mass, per 100 parts by mass of component (A). When multiple types of component (A) are used, it is preferable that the total amount thereof satisfies the above relationship. Similarly, when multiple types of component (D) are used, it is preferable that the total amount thereof satisfies the above relationship. By keeping the amount within the above range, a photocurable resin composition can be obtained that forms a cured product with even better hot water resistance.

[0031] Furthermore, the photocurable resin composition according to the present invention preferably contains silica powder as component (E). Component (E) enables the production of a photocurable resin composition that forms a cured product with even less compression set and excellent hot water resistance. Component (E) is preferably silica powder that has been hydrophobized with organochlorosilane, dimethylsilicone, hexamethyldisilazane, or the like.

[0032] Examples of commercially available products of (E) include Aerosil (registered trademark) R974, R972, R972V, R972CF, R805, R812, R812S, R816, R8200, RY200, RX200, RY200S, and R202 manufactured by Nippon Aerosil Co., Ltd., and Nipsil SS-50A, SS-50YC, and SS-50B manufactured by Tosoh Silica Corporation.

[0033] The average particle size of component (E) is not particularly limited, but the lower limit is, for example, 0.01 μm, more preferably 0.1 μm, and particularly preferably 0.5 μm. The upper limit is, for example, 10 μm, more preferably 5 μm, and particularly preferably 3 μm. Component (E) having such an average particle size is preferred from the viewpoint of obtaining a photocurable resin composition that forms a cured product with even less compression set. The average particle size is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by laser diffraction scattering.

[0034] The amount of component (E) blended is not particularly limited, but is preferably 3 to 80 parts by mass, more preferably 5 to 60 parts by mass, and particularly preferably 10 to 50 parts by mass, per 100 parts by mass of component (A). Within the above range, a photocurable resin composition can be obtained that forms a cured product with even less compression set and excellent hot water resistance. When multiple types of component (A) are used, it is preferable that the total amount thereof satisfies the above relationship. Similarly, when multiple types of component (E) are used, it is preferable that the total amount thereof satisfies the above relationship.

[0035] The photocurable resin composition of the present invention may contain, within the limits that do not impair its properties, an appropriate amount of a (meth)acrylate monomer having one or more (meth)acryloyl groups in one molecule (excluding the components (A) and (B)), an antifoaming agent, a rheology control agent, an antioxidant, etc. Addition of these can improve workability and heat resistance.

[0036] The photocurable resin composition of the present invention can contain a (meth)acrylate monomer (excluding the above-mentioned component (A) and component (B)) having one or more (meth)acryloyl groups in one molecule. The (meth)acrylate monomer can include monofunctional, bifunctional, and trifunctional (meth)acrylate monomers and (meth)acrylamide monomers. Two or more types of (meth)acrylate monomers may be used in combination. The molecular weight of these (meth)acrylate monomers is not particularly limited, but is, for example, less than 1,000. When a (meth)acrylate monomer having one or more (meth)acryloyl groups in one molecule (excluding the components (A) and (B)) is contained, the (meth)acrylate monomer having one or more (meth)acryloyl groups in one molecule (excluding the components (A) and (B)) is preferably less than 50% by mass, more preferably less than 35% by mass, more preferably less than 10% by mass, and most preferably 0% by mass, of the total mass% of the component (B) and the (meth)acrylate monomer having one or more (meth)acryloyl groups in one molecule (excluding the components (A) and (B)). By being in this range, there is no risk of reducing warm water resistance.

[0037] Specific examples of the monofunctional (meth)acrylate monomer other than the components (A) and (B) include aliphatic (meth)acrylates such as 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, cyclopentyl (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, and the like. aromatic (meth)acrylates such as 2-naphthyl (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, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene 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;Heterocyclic (meth)acrylates such as 2-tetrahydrofurfuryl (meth)acrylate, N-(meth)acryloyloxyethyl hexahydrophthalimide, 2-(meth)acryloyloxyethyl-N-carbazole, caprolactone-modified versions of these, ω-carboxy-polycaprolactone mono(meth)acrylate, glycidyl (meth)acrylate, α-ethylglycidyl (meth)acrylate, α-propylglycidyl (meth)acrylate, α-butylglycidyl (meth)acrylate , 2-methylglycidyl (meth)acrylate, 2-ethylglycidyl (meth)acrylate, 2-propylglycidyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 3,4-epoxyheptyl (meth)acrylate, α-ethyl-6,7-epoxyheptyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether compounds having an ethylenically unsaturated group such as methyl ether and an epoxy group; esters 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; Examples of the compound include a compound having an ethylenically unsaturated group and an oxetanyl group; a compound having an ethylenically unsaturated group and an isocyanate group, such as 2-(meth)acryloxyethyl isocyanate; and a compound 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.

[0038] 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, and ethylene oxide-modified neopentyl glycol di(meth). ) acrylate, propylene oxide side-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, di(meth)acryloyl isocyanurate, and the like, but are not limited to these.

[0039] Examples of the defoaming agent include silica-based compounds, amide-based compounds, silicone-based (including polysiloxane-based) compounds, and paraffin-based mineral oils, but in the present invention, silicone-based (including polysiloxane-based) defoaming agents are preferred in terms of their defoaming effect. From the viewpoints of improving the defoaming properties of the photocurable resin composition of the present invention and not reducing the warm water resistance, the blending amount of the defoaming agent is preferably 0.1 to 5 mass%, more preferably 0.5 to 3 mass%, relative to 100 mass% of the total photocurable resin composition.

[0040] The rheology control agent generally refers to an additive that controls the rheological properties of a composition when added to the composition, and is called a thixotropic agent, an anti-settling agent, an anti-sagging agent, a thickener, etc. Examples of the rheology control agent include inorganic rheology control agents such as amorphous silicon dioxide, montmorillonite, bentonite, and colloidal alumina; polyolefin rheology control agents such as polyethylene and polypropylene; cellulose rheology control agents such as nitrocellulose, carboxymethyl cellulose, methyl cellulose, and hydroxyethyl cellulose; alginic acid rheology control agents such as sodium alginate; protein rheology control agents such as casein, sodium caseinate, and ammonium caseinate; and polyvinyl rheology control agents such as polyvinyl alcohol and polyvinylpyrrolidone. Examples of rheology control agents include polyacrylic acid-based rheology control agents such as sodium polyacrylate; polyether-based rheology control agents such as polyether dialkyl esters and polyether dialkyl ethers; urea-based 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-based rheology control agents such as polyhydroxycarboxylic acid amides. Among these, polycarboxylic acid-based rheology control agents are preferred from the viewpoint of not reducing hot water resistance, and rheology control agents containing polyhydroxycarboxylic acid amides are more preferred. To improve the workability of the photocurable resin composition of the present invention and not reduce hot water resistance, the amount of rheology control agent blended is preferably 0.01 to 5 mass%, more preferably 0.05 to 3 mass%, based on 100 mass% of the total photocurable resin composition.

[0041] The antioxidant may be a phenolic antioxidant, a hindered phenolic antioxidant, an organic sulfur antioxidant, an amine antioxidant, a benzotriazole antioxidant, or the like. Among these, from the viewpoint of not reducing the hot water resistance, a phenolic antioxidant is preferred, and dibutylhydroxytoluene (BHT) is more preferred. From the viewpoint of not reducing the hot water resistance of the photocurable resin composition of the present invention, the amount of antioxidant added is preferably 0.001 to 3 mass%, more preferably 0.01 to 2 mass%, relative to 100 mass% of the entire photocurable resin composition.

[0042] The photocurable resin composition of the present invention can be produced by a conventional method. For example, it can be produced by blending predetermined amounts of components (A) to (D), and optionally, component (E) and other components, and mixing them using a mixing means such as a mixer (e.g., a planetary mixer) at a temperature of preferably 10 to 70°C for preferably 0.1 to 5 hours. It is also preferable to produce the composition in a light-shielded environment.

[0043] <Application method> The curable resin composition of the present invention can be applied to an adherend by a known method for applying a resin composition, such as dispensing using an automatic coater, spraying, inkjet printing, screen printing, gravure printing, dipping, or spin coating.

[0044] <Curing method> When the photocurable resin composition of the present invention is cured by irradiating it with active energy rays such as ultraviolet rays or visible light, the source of the active energy rays 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, an electron beam irradiation device, etc. The exposure dose of the active energy rays is 3 kJ / m 2 from the viewpoint of the properties of the cured product. 2 It is preferable that the concentration is equal to or higher than 5 kJ / m 2From the viewpoint of the takt time of the curing process, 2 It is preferably less than 60 kJ / m 2 or less, and particularly preferably 50 kJ / m 2 The following is the result.

[0045] <Adherend> The photocurable resin composition of the present invention can be used on any of a variety of adherends, including, but not limited to, metal-metal, metal-plastic, metal-rubber, metal-glass, plastic-rubber, plastic-glass, plastic-plastic, rubber-rubber, rubber-glass, and glass-glass. Metals include, but are not limited to, gold, silver, iron, aluminum, magnesium, copper, stainless steel, and titanium. Plastics include, but are not limited to, fiber-reinforced plastics (FRP), carbon fiber-reinforced plastics (CFRP), polyacrylic, polyester, polyamide, acrylonitrile-butadiene-styrene, nylon 6, polycarbonate, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyphenylene ether, polyether ether ketone, polyethylene, polypropylene, and polyethylene naphthalate. Rubbers include, but are not limited to, nitrile rubber, butyl rubber, urethane rubber, silicone rubber, and EPDM. 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.

[0046] <Application> In view of the low moisture permeability derived from component (A) and the hot water resistance obtained by combining components (B) to (D), 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 and medical instruments and devices, etc. Among these, the photocurable resin composition of the present invention is particularly preferred for use in fuel cells due to its excellent hot water resistance.

[0047] The fuel cell of the present invention is characterized by being sealed with the photocurable resin composition of the present invention or a cured product thereof. Components requiring sealing in a fuel cell include separators, frames, polymer electrolyte membranes, fuel electrodes, air electrodes, and membrane electrodes (MEAs), and seals can be formed between these components. More specific sealed locations (where seals can be formed) include between adjacent separators, between a separator and a frame, and between a frame and a polymer electrolyte membrane or an MEA. A cured product can be obtained by curing the photocurable resin composition of the present invention or the sealant of the present invention through irradiation with energy rays such as light. The photocurable resin composition or sealant of the present invention, or a cured product thereof, can be used as a seal around components such as separators, frames, polymer electrolyte membranes, fuel electrodes, air electrodes, and membrane electrode assemblies for fuel cells. The photocurable resin composition or sealant of the present invention, or a cured product thereof, can be suitably used for a seal between adjacent separators in a fuel cell, or for a seal between a fuel cell frame and a polymer electrolyte membrane or a membrane electrode assembly. The main purpose of the seal "between the separator and the frame" or "between the polymer electrolyte membrane or MEA and the frame" is to prevent gas mixing and leakage, while the purpose of the seal between adjacent separators is to prevent gas leakage and to prevent cooling water from leaking to the outside from the cooling water flow path.

[0048] <Sealing method> The photocurable resin composition of the present invention is preferably used as a sealant, which is applied to gaps between one or more adherends to keep the interior airtight and prevent leakage or the intrusion of moisture from the outside, i.e., to seal the gaps.

[0049] 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), and MIPG (molded-in-place gasket). [Example]

[0050] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0051] [Examples 1 to 3, Comparative Examples 1 to 4] The following components were prepared to prepare a photocurable resin composition. <Component (A)> (A-1): Polyisobutylene having (meth)acryloyl groups; Number of (meth)acryloyl functional groups: 2; Product name: EPION EP400V (Kaneka Corporation) <Component (B) and comparative component> (B-1): n-Octyl acrylate, product name: NOAA (manufactured by Osaka Organic Chemical Industry Co., Ltd.) (B'-1): Isobornyl acrylate, product name: Light Ester IB-XA (manufactured by Kyoeisha Chemical Co., Ltd.) <Component (C) and comparative component> (C-1): Aromatic polycarbodiimide compound having an ether group (not containing an isocyanate group) Trade name: Elastostab H01 (manufactured by Nisshinbo Chemical Inc.) (C-2): Alicyclic polycarbodiimide compound having an ether group (not containing an isocyanate group) Trade name: Carbodilite V-02B (manufactured by Nisshinbo Chemical Inc.) (C'-1): Polycarbodiimide compound having no hydrophilic group, 50% by mass solution in toluene (containing no isocyanate group) Product name: Carbodilite V-03 (manufactured by Nisshinbo Chemical Inc.) (C'-2): Aromatic polycarbodiimide compound (containing isocyanate groups) having no hydrophilic groups. Product name: Carbodilite V-05 (manufactured by Nisshinbo Chemical Inc.) <(D) component> (D-1): 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, product name: Omnirad (registered trademark) TPO (manufactured by IGM Resins BV) <(E) component> (E-1): Dimethyl silicone surface-treated hydrophobic silica powder (average particle size 2.9 μm, spherical) Product name: Nipsil SS-50A (manufactured by Tosoh Silica Corporation) <Other> Silicone-based defoamer (a mixture of hydrophobic particles and foam-breaking polysiloxane) Product name: BYK-1799 (BYK Japan) Antioxidant (dibutylhydroxytoluene, BHT) reagent

[0052] Examples 1 to 3 and Comparative Examples 1 to 4 were prepared. Components (B) and (D) were weighed into a stirring vessel in the dark and stirred at 40 to 60°C for 1 hour. The remaining components were then weighed into a stirring vessel and stirred for an additional 30 minutes in the dark. Detailed amounts prepared are shown in Table 1, and all values ​​are expressed in parts by mass.

[0053] [Table 1]

[0054] Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to a warm water resistance test.

[0055] [Hot water resistance test] Each photocurable resin composition was applied to a 25mm x 100mm SUS plate using an automatic applicator in a linear bead shape with a height of 1mm, a bead diameter width of 2mm and a length of 80mm, with an accumulated light dose of 40kJ / m 2 The test pieces were cured by irradiating them with ultraviolet light at 100°C to prepare test pieces. Next, the test pieces were compressed using a jig and spacer as specified in JIS-K-6262 (2013) until the beads were 50% compressed (i.e., compressed by 50% of the bead height). The test pieces were then placed in a pressure-resistant container so that they were completely submerged in water, and the pressure-resistant container was sealed. The pressure-resistant container was then left in a hot-air drying oven set at 120°C for 500 hours. The test pieces were then removed from the pressure-resistant container, lightly wiped with a cloth, and left for 30 minutes. The thickness of each test piece was then measured, and the compression set was calculated using the following formula, which was used to determine the warm water resistance. The results were evaluated based on the following criteria. The results are shown in Table 1. In the present invention, from the viewpoint of excellent reliability when the photocurable resin composition is used as a fuel cell sealant, a compression set of 25% or less is considered acceptable, with a compression set of 23% or less being preferred, and a compression set of 20% or less being more preferred. On the other hand, the lower limit is not particularly limited, but it can be substantially 0% or more, or 1% or more. Compression set [%] = [(thickness of test piece before test - thickness of test piece after hot water resistance test) / (thickness of test piece before test - thickness of spacer)] × 100

[0056] The photocurable resin composition of Example 1, which contained components (A) to (D), yielded a sealant with excellent hot water resistance. Comparative Example 1, which did not contain component (C), had poor hot water resistance. Comparative Examples 2 and 3, which used a polycarbodiimide compound without a hydrophilic group instead of component (C), also had poor hot water resistance. Comparative Example 4, which used isobornyl acrylate instead of component (B), had significantly poor hot water resistance. These findings demonstrate that a photocurable resin composition with excellent hot water resistance can be obtained by combining components (A) to (D). [Industrial Applicability]

[0057] The photocurable resin composition of the present invention can form a cured product having excellent hot water resistance, 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.

Claims

1. A photocurable resin composition comprising the following components (A) to (D): Component (A): one or more (meth)acryloyl groups and —[CH ２ C(CH ３ ) ２ ]- units containing polyisobutylene resin Component (B): a monofunctional (meth)acrylate monomer having an alkyl group (excluding component (A)) Component (C): Polycarbodiimide having a hydrophilic group Component (D): Photoradical polymerization initiator

2. 2. The photocurable resin composition according to claim 1, wherein the component (B) is an acrylate monomer.

3. 2. The photocurable resin composition according to claim 1, wherein the component (B) has a linear alkyl group having 5 to 12 carbon atoms.

4. 3. The photocurable resin composition according to claim 1, wherein the content of the component (C) is 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

5. 3. The photocurable resin composition according to claim 1, wherein the component (D) 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 (E).

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

8. 3. The photocurable resin composition according to claim 1, wherein the photocurable resin composition does not contain any (meth)acrylate monomer having one or more (meth)acryloyl groups in one molecule other than the components (A) and (B).

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

Images