Curable resin composition

Abstract

To provide a curable composition that can improve the storage stability of each liquid before mixing, and can rapidly cure at a room temperature.SOLUTION: Provided is a curable resin composition, which is a curable resin composition that cures by mixing liquid A and liquid B, and in which the liquid A contains a thiourea compound, the liquid B contains a hydroperoxide compound, and a mass ratio of the thiourea compound to the hydroperoxide compound (mass of thiourea compound / mass of hydroperoxide compound) is 5 / 95 to 90 / 10.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable composition. More specifically, the present invention relates to a curable composition that is preferably used, for example, in the formation of a heat dissipation material.

Background Art

[0002] In recent years, with the improvement of the performance of automobile batteries and electronic devices such as personal computers and mobile phones, the amount of heat generated has increased, and thus the demand for heat dissipation materials has been increasing. In order to suppress the temperature rise of a device, heat is transferred to a cooling medium such as cooling water, or the temperature rise is suppressed through heat conduction to a heat sink using a metal plate having a high thermal conductivity such as aluminum or copper. In order to efficiently transfer heat from a heat source to a cooling medium or a heat sink, it is advantageous to bring the heat source into close contact with or thermally connect the cooling medium or the heat sink as much as possible, and for this purpose, a heat dissipation material can be used. For example, Patent Document 1 describes a resin composition for a heat dissipation material containing a liquid resin having (meth)acrylic polymer (A), polymerizable monomer (B), and plasticizer (C) as essential components, wherein the cured product of the liquid resin has a hardness of 5 to 70, and it is described that a cured product having good moldability and flexibility of a heat dissipation sheet can be efficiently obtained. Further, Patent Document 2 discloses a curable composition containing a compound (A) having one (meth)acrylate group in one molecule, a compound (B) having two or more (meth)acrylate groups in one molecule, a polymerization initiator (C), a dispersant (D), and a thermally conductive filler (E) containing zinc oxide. Patent Document 2 describes that according to the above composition, a curable composition or its cured product excellent in flexibility, shape stability, and thermal conductivity is provided, and a curable composition or its cured product excellent in suppressing changes in thermal conductivity under a high-temperature environment is provided, and a curable composition or its cured product excellent in flexibility, shape stability, and thermal conductivity can be obtained.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-048124 [Patent Document 2] International Publication No. 2020 / 149193 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In recent years, mixed-type curable resin compositions that are applied to a heating element before curing and then cured after application have attracted attention. From the viewpoint of increasing the surface area of ​​heat sinks, improving the efficiency of their manufacture, and simplifying the manufacturing process of heat sinks, there has been a demand for resin compositions for heat sinks that can be rapidly cured on the production line without heating. However, it has been found that, depending on the embodiment, there may also be a demand for improved storage stability of each liquid before mixing. [Means for solving the problem]

[0005] In view of the above-mentioned problems, the inventors conducted research and found that a curable resin composition that hardens when liquid A and liquid B are mixed, wherein liquid A contains a thiourea compound and liquid B contains a hydroperoxide compound, and the mass ratio of the thiourea compound to the hydroperoxide compound (mass of thiourea compound / mass of hydroperoxide compound) is 5 / 95 to 90 / 10, can improve the storage stability of each liquid before mixing and can harden rapidly at room temperature, thus completing the present invention. [Effects of the Invention]

[0006] The present invention provides a curable composition that can improve the storage stability of each liquid before mixing and can be rapidly cured at room temperature. [Modes for carrying out the invention]

[0007] The curable composition of this disclosure is a curable resin composition in which liquid A contains a thiourea compound and liquid B contains a hydroperoxide compound, and the mass ratio of the thiourea compound to the hydroperoxide compound (mass of thiourea compound / mass of hydroperoxide compound) is 5 / 95 to 90 / 10. The curable composition of this disclosure comprises liquid A and liquid B separated. The curable composition of this disclosure may also comprise components other than liquid A and liquid B separated.

[0008] <Thiourea compounds> Solution A of this disclosure contains a thiourea compound. A thiourea compound refers to a compound having the structure =NC(=S)-N=, and includes not only compounds in which the oxygen atom of urea is replaced with a sulfur atom (thiourea), but also known thiourea structural analogs. The thiourea compounds of this disclosure include thiourea compounds represented by the following general formula (1) (hereinafter also referred to as thiourea compounds).

[0009] [ka]

[0010] (In the formula, R1, R2, R3, and R4 represent hydrogen, an alkyl group, a phenyl group, a tolyl group, a methoxyphenyl group, or a naphthyl group.) The alkyl group of the thiourea compound represented by general formula (1) of this disclosure is a linear, branched, or cyclic alkyl group, preferably having 1 to 20 carbon atoms, more preferably having 1 to 13 carbon atoms, and even more preferably having 1 to 8 carbon atoms.

[0011] Examples of linear alkyl groups in this disclosure include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, etc. From the viewpoint of solubility in monomers, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, and n-decyl group are preferred. Examples of branched alkyl groups in this disclosure include t-butyl group, isobutyl group, isopentyl group, t-pentyl group, neopentyl group, isohexyl group, isoheptyl group, isooctyl group (2-ethylhexyl group), isononyl group, isodecyl group, and the like. Examples of cyclic alkyl groups in this disclosure include cyclopentyl group, cyclohexyl group, cycloheptyl group, isobornyl group, and 4-t-butylcyclohexyl group.

[0012] The thiourea compound represented by general formula (1) of this disclosure preferably has R1 and R3 as alkyl groups or phenyl groups. Specifically, the thiourea compounds represented by the general formula (1) of this disclosure include N-methylthiourea, N-ethylthiourea, N-propylthiourea, N-butylthiourea, N-laurylthiourea, N-cyclohexylthiourea, N,N'-dimethylthiourea, N,N'-diethylthiourea, N,N'-dipropylthiourea, N,N'-dibutylthiourea, N,N'-dihexylthiourea, N,N'-dioctylthiourea, N,N'-bis(1-methylethyl)thiourea, N,N'-bis(1,1-dimethylethyl)thiourea, N,N'-bis(1-methylpropyl)thiourea, 1-isopropyl-3-t-butylthiourea, N,N-dicyclohexylthiourea, trimethylthiourea, N,N'-diphenylthiourea, and N-phenyl Examples include ruthiourea, 4-methoxyphenylthiourea, 1,3-bis(4-methoxyphenyl)thiourea, p-tolylthiourea, 1,3-di(p-tolyl)thiourea, 1-methyl-3-phenylthiourea, N-propylthiourea, N-butylthiourea, N-laurylthiourea, N-cyclohexylthiourea, N,N'-diethylthiourea, N,N'-dipropylthiourea, N,N'-dibutylthiourea, N,N'-dihexylthiourea, N,N'-dioctylthiourea, N,N'-bis(1-methylethyl)thiourea, N,N'-bis(1,1-dimethylethyl)thiourea, N,N'-bis(1-methylpropyl)thiourea, 1-isopropyl-3-t-butylthiourea, N,N-dicyclohexylthiourea, N, N-diphenylthiourea and N-phenylthiourea are preferred.

[0013] <Radical polymerizable monomers> The curable compositions of this disclosure may contain radical polymerizable monomers. A radical polymerizable monomer is a compound having one polymerizable group, and preferably a compound having one polymerizable double bond. The radical polymerizable monomer may be included in solution A or solution B, or in any other solution. When the curable composition is a mixture of two liquids, liquid A and liquid B, it is preferable that the radical polymerizable monomer is included in liquid A.

[0014] The radical polymerizable monomer of the present disclosure is not particularly limited. For example, alkyl (meth)acrylate, cycloalkyl (meth)acrylate, hydroxyl group-containing (meth)acrylate, aromatic monomer having a carbon-carbon double bond, carbon-carbon double bond-containing monomer having a carboxyl group, carbon-carbon double bond-containing monomer having a nitrogen atom, carbon-carbon double bond-containing monomer having an oxo group, carbon-carbon double bond-containing monomer having a fluorine atom, carbon-carbon double bond-containing monomer having an epoxy group, etc. can be mentioned, but the present invention is not limited to such examples only. These other monomers may be used alone or in combination of two or more kinds.

[0015] In the present invention, “(meth)acrylic” means “acrylic” or “methacrylic”, and “(meth)acrylate” means “acrylate” or “methacrylate”.

[0016] Among the radical polymerizable monomers, from the viewpoint of rapidly curing the resin composition at room temperature, alkyl (meth)acrylate, cycloalkyl (meth)acrylate, hydroxyl group-containing (meth)acrylate, aromatic monomer having a carbon-carbon double bond, and carbon-carbon double bond-containing monomer having a carboxyl group are preferable, alkyl (meth)acrylate, hydroxyl group-containing (meth)acrylate, and carbon-carbon double bond-containing monomer having a carboxyl group are more preferable, alkyl (meth)acrylate, cycloalkyl (meth)acrylate, and hydroxyl group-containing (meth)acrylate are even more preferable, alkyl (meth)acrylate and hydroxyl group-containing (meth)acrylate are further preferable, and alkyl (meth)acrylate is even further preferable.

[0017] Examples of the alkyl (meth)acrylate of the present disclosure include alkyl (meth)acrylate having an alkyl group with 1 to 18 carbon atoms, etc., preferably having an alkyl group with 2 to 13 carbon atoms, and more preferably having an alkyl group with 3 to 8 carbon atoms.

[0018] The alkyl (meth)acrylates of this disclosure are linear, branched, or cyclic alkyl groups. From the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to conform to the heat generating element and the heat dissipation material, linear or branched alkyl groups are more preferable. From the viewpoint of rapidly curing the resin composition at room temperature, alkyl (meth)acrylates having cyclic alkyl groups with 3 to 12 carbon atoms are preferred, alkyl (meth)acrylates having cyclic alkyl groups with 3 to 10 carbon atoms are more preferred, and alkyl (meth)acrylates having cyclic alkyl groups with 4 to 8 carbon atoms are even more preferred.

[0019] Examples of the alkyl (meth)acrylate of the present disclosure specifically include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, tridecyl (meth)acrylate, n-lauryl (meth)acrylate, cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc., but the present invention is not limited only to such examples. These alkyl (meth)acrylates may be used alone or in combination of two or more. Among these alkyl (meth)acrylates, from the viewpoint of enhancing the flexibility of the heat dissipation material after curing and enhancing the followability of the heat dissipation material to the heating element and the heat dissipation body, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate are preferable, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are more preferable, and from the viewpoint of rapidly curing the resin composition at room temperature, cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate are preferable, and cyclopentyl (meth)acrylate and cyclohexyl (meth)acrylate are more preferable.

[0020] The alkyl (meth)acrylate content in the radical polymerizable monomer is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, and still more preferably 80 parts by mass or more, from the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to conform to the heat generating element and the heat dissipation material, with an upper limit of 100 parts by mass. Therefore, the alkyl (meth)acrylate content in the radical polymerizable monomer is preferably 50 to 100 parts by mass, more preferably 60 to 100 parts by mass, even more preferably 70 to 100 parts by mass, and still more preferably 80 to 100 parts by mass. The content of alkyl(meth)acrylate having a cyclic alkyl group in the radical polymerizable monomer is preferably 0 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, from the viewpoint of improving the toughness of the heat dissipation material after curing, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, from the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to conform to the heat generating element and the heat dissipation material.

[0021] The content of alkyl(meth)acrylate having a linear or branched alkyl group in 100 parts by mass of the alkyl(meth)acrylate of this disclosure is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and may be 100 parts by mass, from the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to conform to the heat generating element and the heat dissipation material.

[0022] Examples of hydroxyl group-containing (meth)acrylates include hydroxyl group-containing (meth)acrylates with 1 to 18 carbon atoms in the ester portion, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and glycerin mono(meth)acrylate. However, the present invention is not limited to these examples. These hydroxyl group-containing (meth)acrylates may be used individually or in combination of two or more. Among these hydroxyl group-containing (meth)acrylates, 2-hydroxyethyl (meth)acrylate and glycerin mono(meth)acrylate are preferred from the viewpoint of rapidly curing the resin composition at room temperature, 2-hydroxyethyl (meth)acrylate is more preferred, and 2-hydroxyethyl acrylate is even more preferred.

[0023] The content of hydroxyl group-containing (meth)acrylate in the radical polymerizable monomer is preferably 0 parts by mass or more, more preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of improving the dispersion stability of the resin composition, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, from the viewpoint of lowering the viscosity of the resin composition. Therefore, the content of hydroxyl group-containing (meth)acrylate in the radical polymerizable monomer is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, and even more preferably 0.5 to 5 parts by mass.

[0024] Examples of aromatic monomers having carbon-carbon double bonds include styrene, α-methylstyrene, p-methylstyrene, tert-methylstyrene, chlorostyrene, aralkyl (meth)acrylate, and vinyltoluene, but the present invention is not limited to these examples. Examples of aralkyl (meth)acrylates include benzyl (meth)acrylate, phenylethyl (meth)acrylate, methylbenzyl (meth)acrylate, naphthylmethyl (meth)acrylate, and other aralkyl (meth)acrylates having aralkyl groups with 7 to 18 carbon atoms, but the present invention is not limited to these examples. These aromatic monomers may be used individually or in combination of two or more types. Among these aromatic monomers, styrene is preferred from the viewpoint of rapidly curing the resin composition at room temperature.

[0025] The content of aromatic monomers having carbon-carbon double bonds in the radical polymerizable monomer is preferably 0 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, from the viewpoint of improving the toughness of the heat dissipation material after curing, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, from the viewpoint of rapidly curing the resin composition at room temperature. Therefore, the content of aromatic monomers in the radical polymerizable monomer is preferably 0 to 10 parts by mass, more preferably 1 to 10 parts by mass, even more preferably 2 to 8 parts by mass, and even more preferably 3 to 8 parts by mass.

[0026] Examples of carbon-carbon double bond-containing monomers having a carboxyl group include (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, and maleic anhydride, which are aliphatic monomers having a carboxyl group or acid anhydride group; however, the present invention is not limited to these examples. These carbon-carbon double bond-containing monomers having a carboxyl group may be used individually or in combination of two or more types. Among these carbon-carbon double bond-containing monomers having a carboxyl group, (meth)acrylic acid is preferred from the viewpoint of rapidly curing the resin composition at room temperature.

[0027] The content of the carboxyl group-containing carbon-carbon double bond monomer in the radical polymerizable monomer is preferably 0 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.3 parts by mass or more, from the viewpoint of improving the dispersion stability of the resin composition, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, from the viewpoint of lowering the viscosity of the resin composition. Therefore, the content of the carboxyl group-containing carbon-carbon double bond monomer in the radical polymerizable monomer is preferably 0 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, even more preferably 0.2 to 3 parts by mass, and even more preferably 0.3 to 2 parts by mass.

[0028] Examples of nitrogen atom-containing carbon-carbon double bond monomers include (meth)acrylamide compounds such as (meth)acrylamide, diacetone(meth)acrylamide, N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, Nn-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, methylenebis(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and diacetone(meth)acrylamide, as well as dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate, N-vinylpyrrolidone, and (meth)acrylonitrile. However, the present invention is not limited to these examples. These nitrogen atom-containing carbon-carbon double bond monomers may be used individually or in combination of two or more types. Examples of carbon-carbon double bond-containing monomers having an oxo group include (di)ethylene glycol (methoxy)(meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, 2-methoxytriethylene glycol (meth)acrylate, ethylene glycol (meth)acrylate, ethylene glycol methoxy (meth)acrylate, diethylene glycol (meth)acrylate, and diethylene glycol methoxy (meth)acrylate. However, the present invention is not limited to these examples. These oxo group-containing monomers may be used individually or in combination of two or more types.

[0029] Examples of carbon-carbon double bond-containing monomers having a fluorine atom include fluoroalkyl (meth)acrylates having a fluoroalkyl group with 2 to 6 carbon atoms, such as trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, and octafluoropentyl (meth)acrylate. However, the present invention is not limited to these examples. These carbon-carbon double bond-containing monomers having a fluorine atom may be used individually or in combination of two or more types. Examples of epoxy group-containing carbon-carbon double bond monomers include epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate, but the present invention is not limited to these examples. Epoxy group-containing carbon-carbon double bond monomers may be used individually or in combination of two or more types.

[0030] The glass transition temperature of the polymer obtained by polymerizing radical polymerizable monomers is preferably -20°C or lower, more preferably -30°C or lower, from the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to conform to the heat generating element and the heat dissipation material. The lower limit of the glass transition temperature of the polymer is not particularly limited, but is preferably -180°C or higher, more preferably -160°C or higher.

[0031] The curable composition of this disclosure preferably uses an alkyl (meth)acrylate monomer from the viewpoint of dissolving the thiourea compound. The alkyl (meth)acrylate monomer may be contained in solution A or B, or in other solutions, but it is preferable that it be contained in A from the viewpoint of dissolving the thiourea compound.

[0032] <Hydroperoxide compounds> Solution B of this disclosure contains a hydroperoxide compound. The hydroperoxide compounds of the disclosed herein are not particularly limited, but typically act as polymerization initiators during the curing of the curable compositions of the disclosed herein. The inclusion of the peroxides of the disclosed curable compositions tends to result in good initial moldability (pot life) and curability (monomer conversion rate).

[0033] Examples of the hydroperoxide compounds disclosed herein include cumene hydroperoxide, 1,4-diisopropylbenzene hydroperoxide, 1,3-diisopropylbenzene hydroperoxide, 4-t-butylcumene hydroperoxide, 1,3-dimethyl-1-phenylbutyl hydroperoxide, diisopropylbenzene hydroperoxide, 1-phenylethyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-butyl hydroperoxide, p-menthane hydroperoxide, t-pentyl hydroperoxide, 1,1-dimethylbutyl hydroperoxide, and 1-methylbutyl. Examples include 1,1-dimethylhexyl hydroperoxide, 1,1-methylhexyl hydroperoxide, 1,1-methylbutyl hydroperoxide, 1,1-dimethylpentyl hydroperoxide, 1,1,2,2-tetramethylpropyl hydroperoxide, and 3-heptyl hydroperoxide. From the viewpoint of storage stability and handling ease, cumene hydroperoxide, 1,4-diisopropylbenzene hydroperoxide, 1,3-diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-butyl hydroperoxide, and p-menthane hydroperoxide are more preferred. In addition to thiourea compounds, radical polymerizable monomers, and hydroperoxide compounds, the curable resin compositions of this disclosure may also contain polymers, plasticizers, crosslinking agents, and other additives.

[0034] <polymer> Examples of polymers in this disclosure include (meth)acrylic polymers, polyester polymers, polyurethane polymers, silicone polymers, and epoxy polymers, with (meth)acrylic polymers being preferred from the viewpoint of cost, design flexibility, and filler dispersibility.

[0035] The (meth)acrylic polymers of this disclosure have structural units derived from (meth)acrylic monomers. The structural units derived from (meth)acrylic monomers are units having a structure in which the carbon-carbon double bond of the (meth)acrylic monomer is replaced by a carbon-carbon single bond. The structural units derived from (meth)acrylic monomers can be introduced into the (meth)acrylic polymer by polymerizing the (meth)acrylic monomer. Examples of (meth)acrylic monomers include alkyl (meth)acrylates and hydroxyl group-containing (meth)acrylates, but the present invention is not limited to these examples. These (meth)acrylic monomers may be used individually or in combination of two or more types.

[0036] Examples of alkyl (meth)acrylates used in the (meth)acrylic polymers of this disclosure include alkyl (meth)acrylates with 1 to 18 carbon atoms in the alkyl group, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, tridecyl (meth)acrylate, and n-lauryl (meth)acrylate. However, the present invention is not limited to these examples. These alkyl (meth)acrylates may be used individually or in combination of two or more types. Among these alkyl (meth)acrylates, alkyl (meth)acrylates with 1 to 8 carbon atoms in the alkyl group are preferred from the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to follow the heat generating element and the heat dissipation material, and n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are more preferred.

[0037] The alkyl (meth)acrylate content in 100 parts by mass of (meth)acrylic monomer used in the (meth)acrylic polymer of this disclosure is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, and still more preferably 80 parts by mass or more, with an upper limit of 100 parts by mass, from the viewpoint of increasing the flexibility of the heat dissipation material after curing and improving the heat dissipation material's ability to conform to the heat generating element and the heat dissipation material. Therefore, the alkyl (meth)acrylate content in the (meth)acrylic monomer is preferably 50 to 100 parts by mass, more preferably 60 to 100 parts by mass, even more preferably 70 to 100 parts by mass, and still more preferably 80 to 100 parts by mass.

[0038] Examples of hydroxyl group-containing (meth)acrylates used in the (meth)acrylic polymers of this disclosure include hydroxyl group-containing (meth)acrylates with 1 to 18 carbon atoms in the ester portion, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and glycerin mono(meth)acrylate. However, the present invention is not limited to these examples. These hydroxyl group-containing (meth)acrylates may be used individually or in combination of two or more. Among these hydroxyl group-containing (meth)acrylates, 2-hydroxyethyl (meth)acrylate and glycerin mono(meth)acrylate are preferred from the viewpoint of rapidly curing the resin composition at room temperature, 2-hydroxyethyl (meth)acrylate is more preferred, and 2-hydroxyethyl acrylate is even more preferred. Furthermore, when a thermally conductive material, as described later, is included in solution A, 2-hydroxyethyl (meth)acrylate and glycerin mono(meth)acrylate are preferred, 2-hydroxyethyl (meth)acrylate is more preferred, and 2-hydroxyethyl acrylate is even more preferred, from the viewpoint of improving the dispersion stability of the thermally conductive material in solution A.

[0039] The content of hydroxyl group-containing (meth)acrylate in 100 parts by mass of (meth)acrylic monomer used in the (meth)acrylic polymer of this disclosure is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, from the viewpoint of improving the dispersion stability of the resin composition and lowering the viscosity of the resin composition, and preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, from the viewpoint of lowering the viscosity of the (meth)acrylic polymer and improving the compatibility between the (meth)acrylic monomer and the radical polymerizable monomer. Therefore, the content of hydroxyl group-containing (meth)acrylate in the (meth)acrylic monomer is preferably 0.3 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 20 parts by mass.

[0040] Furthermore, the (meth)acrylic monomers used in the (meth)acrylic polymers of this disclosure may include, to the extent that the objectives of the present invention are not hindered, other monomers besides those mentioned above, such as cycloalkyl (meth)acrylates including cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; carbon-carbon double bond-containing monomers having a carboxyl group such as (meth)acrylic acid; carbon-carbon double bond-containing monomers having a silane group; carbon-carbon double bond-containing monomers having a nitrogen atom; carbon-carbon double bond-containing monomers having an oxo group; carbon-carbon double bond-containing monomers having a fluorine atom; carbon-carbon double bond-containing monomers having an epoxy group; carbon-carbon double bond-containing monomers having an aralkyl group; and aromatic monomers having a carbon-carbon double bond such as styrene.

[0041] Examples of polyester polymers in this disclosure include polymers having a polyester main chain structure obtained by condensing glycols such as ethylene glycol, propylene glycol, neopentyl glycol, and tetramethylene glycol with dicarboxylic acids such as terephthalic acid, isophthalic acid, sebacic acid, succinic acid, phthalic acid, and adipic acid. Examples of polyurethane polymers in this disclosure include polyurethane main chain structures obtained by reacting polyols such as polyether polyols, polyester polyols, castor oil-based polyols, hydrogenated castor oil-based polyols, polycarbonate polyols, polybutadiene polyols, polyisoprene polyols, and hydrogenated polyisoprene polyols with diisocyanates such as xylylene diisocyanate, isophorone diisocyanate, methylenediphenyl diisocyanate, and toluene diisocyanate.

[0042] <Plasticizer> Examples of plasticizers in this disclosure include trimellitic acid ester plasticizers such as tri-2-ethylhexyl trimellitate, tri-n-octyl trimellitate, and triisononyl trimellitate; phthalate ester plasticizers such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, diisononyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, diisodecyl phthalate, ditridecyl phthalate, and diundecyl phthalate; and di-n-butyl adipate and diisobutyl adipate. Adipate ester plasticizers such as dibutoxyethyl adipate, di-n-octyl adipate, diisooctyl adipate, diisononyl adipate, bis-2-ethylhexyl adipate, and diisodecyl adipate; phosphate ester plasticizers such as tributyl phosphate, tri(2-ethylhexyl) phosphate, trioctyl phosphate, triphenyl phosphate, diphenyl-2-ethylhexyl phosphate, and tricresyl phosphate; and sebacate such as dibutyl sebacate, dioctyl sebacate, and di-2-ethylhexyl sebacate. Basic acid ester plasticizers; azelaic acid ester plasticizers such as dihexyl azelate and dioctyl azelate; citrate ester plasticizers such as triethyl citrate, acetyl triethyl citrate, and tri-n-butyl citrate; glycolic acid ester plasticizers such as methyl phthalyl ethyl glycolate and ethyl phthalyl ethyl glycolate; trimellitic acid ester plasticizers such as trioctyl trimellitate, tri-n-octyl-n-decyl trimellitate, and trialkyl trimellitate (number of carbon atoms in the alkyl group: 4-11); methyl acetyl Examples of plasticizers include ricinoleic acid ester plasticizers such as luricinolate, butylacetylricinolate, and glycerol monoricinolate; maleic acid ester plasticizers such as di-n-butylmalate; itaconic acid ester plasticizers such as monobutylitaconate; oleic acid ester plasticizers such as butyloleate; and glycerol-based plasticizers such as glycerol monoacetomolaurate, glycerol diacetomolaurate, glycerol monoacetomostearate, and glycerol diacetomooleate. However, the present invention is not limited to these examples.These plasticizers may be used individually or in combination of two or more. Among these plasticizers, trimellitic acid ester plasticizers are preferred from the viewpoint of preventing vaporization of the plasticizer and improving its thermal stability over a long period of time.

[0043] <Crosslinking agent> The curable composition of this disclosure may contain a crosslinking agent. The crosslinking agent is a compound containing two or more polymerizable groups, and is preferably a compound having two or more polymerizable double bonds. The crosslinking agent may be included in solution A or solution B, or in any other solution. When the curable composition is a mixture of two liquids, liquid A and liquid B, it is preferable that the crosslinking agent is included in liquid A.

[0044] The crosslinking agent used in this disclosure is at least one crosslinking agent selected from the group consisting of (meth)acrylate crosslinking agents and allyl crosslinking agents. The (meth)acrylate crosslinking agent and the allyl crosslinking agent may be used individually or in combination. Examples of (meth)acrylate crosslinking agents include (poly)ethylene glycol di(meth)acrylates such as tetraethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, urethane(meth)acrylate, triacryl isocyanurate, and triacryl cyanurate, but the present invention is not limited to these examples. These (meth)acrylate crosslinking agents may be used individually or in combination of two or more types.

[0045] Examples of allyl crosslinking agents include polyfunctional allyl esters and polyfunctional allyl ethers, but the present invention is not limited to these examples. These allyl crosslinking agents may be used individually or in combination of two or more. Allyl crosslinking agents have the advantage of increasing the mechanical strength of the crosslinked body of the heat dissipation material obtained from the resin composition, even in areas that are not covered with a masking film or the like when curing the resin composition.

[0046] A polyfunctional allyl ester is an allyl ester having two or more allyl groups in one molecule. Examples of polyfunctional allyl esters include allyl group-containing cyanurate compounds such as triallyl isocyanurate and triallyl cyanurate, and general formula (2): X-[COOCH2CH=CH2]n (2) Examples include aliphatic polyfunctional allyl esters represented by the formula (wherein X is an n-valent aliphatic hydrocarbon group and n is the valency of the aliphatic hydrocarbon group), but the present invention is not limited to these examples. These polyfunctional allyl esters may be used individually or in combination of two or more types.

[0047] Examples of aliphatic polyfunctional allyl esters represented by general formula (2) include diallyl oxalate, diallyl malonate, diallyl succinate, diallyl glutarate, diallyl adipate, diallyl pimelate, diallyl suberate, diallyl azelaate, diallyl sebacate, diallyl fumarate, diallyl maleate, trialyl citrate, diallyl tartrate, diallyl itaconate, and diallyl citraconate, but the present invention is not limited to these examples.

[0048] Polyfunctional allyl ethers are allyl ethers having two or more allyl groups in one molecule. Examples of polyfunctional allyl ethers include glycerin diallyl ether, glycerin triallyl ether, 1,4-butanediol diallyl ether, nonanediol diallyl ether, 1,4-cyclohexane dimethanol diallyl ether, triethylene glycol diallyl ether, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, ditrimethylolpropane tetraallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, dipentaerythritol pentaallyl ether, dipentaerythritol hexaallyl ether, sorbitol diallyl ether, 1,3-bis(allyloxy)adamantane, and 1,3,5-tris(allyl Examples include oxy)adamantane, bisphenol S diallyl ether, bisphenol A diallyl ether, bisphenol A alkylene oxide diallyl ether, bisphenol F alkylene oxide diallyl ether, 2,5-diallylphenol allyl ether, novolacphenol allyl ether, allylated polyphenylene oxide, compounds in which the glycidyl group of epoxy resin is substituted with an allyl group, 1,1,2,2-tetraallyloxyethane, ethylene glycol diallyl ether, diethylene glycol diallyl ether, polyethylene glycol diallyl ether, propylene glycol diallyl ether, butylene glycol diallyl ether, hexanediol diallyl ether, and the like, but the present invention is not limited to these examples.

[0049] Among crosslinking agents, allyl crosslinking agents are preferred from the viewpoint of increasing the flexibility of the heat dissipation material after curing, improving the heat dissipation material's ability to conform to the heat generating element and heat dissipation element, and increasing the mechanical strength of the crosslinked body of the heat dissipation material obtained from the resin composition. Allyl group-containing cyanurate compounds are more preferred, and triallyl isocyanurate and triallyl cyanurate are even more preferred from the viewpoint of improving curability, with triallyl cyanurate being even more preferred. Furthermore, when a (meth)acrylate-based crosslinking agent and an allyl-based crosslinking agent are used in combination as crosslinking agents, the synergistic effect of using both together increases the flexibility of the heat dissipation material after curing, improves the heat dissipation material's ability to conform to the heat generating element and heat sink, and further increases the mechanical strength of the crosslinked body (also called the cured product) of the heat dissipation material obtained from the resin composition.

[0050] When a (meth)acrylate-based crosslinking agent and an allyl-based crosslinking agent are used in combination, the synergistic effect of using both agents increases the flexibility of the heat dissipation material after curing and improves the heat dissipation material's ability to follow the heat source and heat source. From this viewpoint, the mass ratio of the allyl-based crosslinking agent to the (meth)acrylate-based crosslinking agent [allyl-based crosslinking agent / (meth)acrylate-based crosslinking agent] is preferably 20 / 80 to 85 / 15, more preferably 30 / 70 to 75 / 25, and even more preferably 40 / 60 to 65 / 35, and 45 / 55 to 55 / 45 in that order. The crosslinking agent may include, for example, diene-based crosslinking agents such as 1,5-hexadiene, 1,9-decadiene, 1,3-diisopropenylbenzene, and 1,4-diisopropenylbenzene, as long as the objective of the present invention is not hindered.

[0051] <Thermally conductive materials> The curable compositions of this disclosure may include thermally conductive materials. Examples of thermally conductive materials include alkali metal carbonate particles such as sodium carbonate particles, sodium bicarbonate particles, potassium carbonate particles, and potassium bicarbonate particles; alkaline earth metal carbonate particles such as magnesium carbonate particles, calcium carbonate particles, and barium carbonate particles; carbonate particles such as ammonium carbonate particles, ammonium bicarbonate particles, and other ammonium carbonate salt particles; zinc oxide particles, aluminum oxide particles, magnesium oxide particles, beryllium oxide particles, calcium oxide particles, zirconium oxide particles, aluminum oxide (alumina) particles, titanium dioxide particles, silica particles, magnesium hydroxide particles, aluminum hydroxide particles, calcium silicate particles, aluminum silicate particles, silicon carbide particles, silicon nitride particles, boron nitride particles, calcium sulfate particles, barium sulfate particles, magnesium carbonate particles, glass particles, kaolin, talc, mica powder, metal particles, and carbon black particles, but the present invention is not limited to these examples. These thermally conductive materials may be used individually or in combination of two or more types. Among these thermally conductive materials, aluminum oxide (alumina) particles are preferred from the viewpoint of improving the thermal conductivity of the heat dissipation material obtained using the curable resin composition of the present invention.

[0052] The average particle diameter of the thermal conductive material is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, from the viewpoint of preventing aggregation of the thermal conductive material, and preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less, from the viewpoint of improving the dispersion stability of the thermal conductive material. Therefore, the average particle diameter of the thermal conductive material is preferably 0.3 to 100 μm, more preferably 0.5 to 80 μm, and even more preferably 1 to 50 μm. Note that the average particle diameter of the thermal conductive material refers to the volume-average particle diameter measured using a laser diffraction scattering particle size distribution analyzer [Beckman Coulter, part number: LS13320].

[0053] In the curable resin composition of this disclosure, the amount of thermal conductive material per 100 parts by mass of the total amount of (meth)acrylic polymer and radical polymerizable monomer is preferably 400 parts by mass or more, more preferably 500 parts by mass or more, and even more preferably 600 parts by mass or more, from the viewpoint of improving the thermal conductivity of the heat dissipation material obtained using the curable resin composition, and preferably 2400 parts by mass or less, more preferably 2200 parts by mass or less, even more preferably 2000 parts by mass or less, and even more preferably 1800 parts by mass or less, from the viewpoint of lowering the viscosity of the curable resin composition and improving the flexibility of the heat dissipation material after curing. Therefore, the amount of thermal conductive material per 100 parts by mass of the total amount of (meth)acrylic polymer and radical polymerizable monomer is preferably 400 to 2400 parts by mass, more preferably 500 to 2200 parts by mass, even more preferably 600 to 2000 parts by mass, and even more preferably 600 to 1800 parts by mass.

[0054] Other additives include, for example, colorants such as pigments, leveling agents, UV absorbers, UV stabilizers, antioxidants, polymerization inhibitors, fillers, coupling agents, rust inhibitors, antibacterial agents, metal deactivators, wetting agents, defoaming agents, surfactants, reinforcing agents, plasticizers, lubricants, antifogging agents, corrosion inhibitors, pigment dispersants, flow regulators, peroxide decomposing agents, mold decolorizing agents, fluorescent whitening agents, organic flame retardants, inorganic flame retardants, anti-dripping agents, molten flow modifiers, antistatic agents, anti-algal agents, antifungal agents, flame retardants, slip agents, metal chelating agents, antiblocking agents, heat-resistant stabilizers, processing stabilizers, dispersants, thickeners, rheology control agents, foaming agents, anti-aging agents, preservatives, antistatic agents, silane coupling agents, antioxidants, and film-forming aids. However, the present invention is not limited to these examples. These additives may be used individually or in combination of two or more types.

[0055] <Composition and physical properties of the curable resin composition of this disclosure> The content of the thiourea compound in 100 parts by mass of the curable resin composition of this disclosure is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, even more preferably 0.03 parts by mass or more, may be 0.04 parts by mass or more, preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, even more preferably 0.3 parts by mass or less, and may be 0.2 parts by mass or less. The curable resin composition of this disclosure preferably contains 0.20 parts by mass or more, more preferably 0.30 parts by mass or more, even more preferably 0.40 parts by mass or more, may be 0.50 parts by mass or more, preferably 1.50 parts by mass or less, more preferably 1.20 parts by mass or less, even more preferably 1.00 parts by mass or less, and may be 0.80 parts by mass or less.

[0056] In the curable resin composition of this disclosure, the content of the thiourea compound per 100 parts by mass of liquid A is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, even more preferably 0.03 parts by mass or more, may be 0.04 parts by mass or more, preferably 1 part by mass or less, more preferably 0.6 parts by mass or less, and may be 0.4 parts by mass or less. In the curable resin composition of this disclosure, when liquid A contains a thermally conductive material, the content of the thiourea compound per 100 parts by mass of liquid A excluding the thermally conductive material is preferably 0.20 parts by mass or more, more preferably 0.40 parts by mass or more, even more preferably 0.60 parts by mass or more, preferably 2.00 parts by mass or less, and more preferably 1.50 parts by mass or less. Even more preferably 1.00 part by mass or less.

[0057] The content of radical polymerizable monomer in 100 parts by mass of the curable resin composition of this disclosure is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2 parts by mass or more, preferably 25 parts by mass or less, and more preferably 20 parts by mass or less. It is even more preferably 15 parts by mass or less, and may be 10 parts by mass or less. The curable resin composition of this disclosure preferably contains 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, preferably 50 parts by mass or less, and more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, and may also be 35 parts by mass or less.

[0058] In the curable resin composition of this disclosure, the content of radical polymerizable monomer per 100 parts by mass of liquid A is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2 parts by mass or more, preferably 30 parts by mass or less, more preferably 27 parts by mass or less, even more preferably 24 parts by mass or less, and may also be 21 parts by mass or less. In the curable resin composition of this disclosure, when liquid A contains a thermally conductive material, the content of radical polymerizable monomers per 100 parts by mass of liquid A excluding the thermally conductive material is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, preferably 70 parts by mass or less, and more preferably 65 parts by mass or less. It is even more preferably 60 parts by mass or less, and may be 55 parts by mass or less.

[0059] The mass ratio of the thiourea compound to the radical polymerizable monomer in the curable composition of this disclosure is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the radical polymerizable monomer.

[0060] The content of the hydroperoxide compound in 100 parts by mass of the curable resin composition of this disclosure is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.12 parts by mass or more, may be 0.15 parts by mass or more, preferably 5 parts by mass or less, more preferably 3 parts by mass or less. It is even more preferably 2 parts by mass or less, and may be 1 part by mass or less. The curable resin composition of this disclosure preferably contains 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.2 parts by mass or more, may also contain 1.5 parts by mass or more, preferably 6 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 4 parts by mass or less, and may also contain 3 parts by mass or less.

[0061] In the curable resin composition of this disclosure, the content of the hydroperoxide compound per 100 parts by mass of liquid B is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. In the curable resin composition of this disclosure, when liquid B contains a thermally conductive material, the content of the hydroperoxide compound per 100 parts by mass of liquid B excluding the thermally conductive material is preferably 2.0 parts by mass or more, more preferably 4.0 parts by mass or more, preferably 25 parts by mass or less, and more preferably 20 parts by mass or less.

[0062] The amount of the hydroperoxide compound added per 100 parts by mass of the radical polymerizable monomer in this disclosure is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, from the viewpoint of rapidly curing the resin composition at room temperature, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, from the viewpoint of extending the pot life of the resin composition and increasing the flexibility of the heat dissipation material after curing.

[0063] The amount of hydroperoxide compound added per 100 parts by mass of the total radical polymerizable monomer and crosslinking agent of this disclosure is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, from the viewpoint of rapidly curing the resin composition at room temperature, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of extending the pot life of the resin composition and increasing the flexibility of the heat dissipation material after curing.

[0064] The mass ratio of the thiourea compound to the hydroperoxide compound (mass of thiourea compound / mass of hydroperoxide compound) in this disclosure is preferably 5 / 95 to 90 / 10, more preferably 10 / 90 to 80 / 20, and even more preferably 11 / 89 to 60 / 40, 12 / 88 to 40 / 60, and 13 / 87 to 30 / 70, in that order.

[0065] The polymer content in 100 parts by mass of the curable resin composition of this disclosure is preferably 0.6 parts by mass or more, more preferably 0.9 parts by mass or more, even more preferably 1.2 parts by mass or more, preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 9 parts by mass or less. The curable resin composition of this disclosure preferably contains 6 parts by mass or more, more preferably 9 parts by mass or more, even more preferably 12 parts by mass or more, preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less per 100 parts by mass of the curable resin composition excluding the thermal conductive material.

[0066] The curable composition of this disclosure preferably contains 70 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, and may be substantially 100 parts by mass, of the total 100 parts by mass of the polymers of this disclosure.

[0067] The content of the silicone polymer in the curable composition of this disclosure is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably substantially absent, based on 100 parts by mass of the total polymers of this disclosure.

[0068] The plasticizer content per 100 parts by mass of the curable resin composition of this disclosure is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. The curable resin composition of this disclosure preferably contains 15 parts by mass or more, more preferably 20 parts by mass or more, preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, per 100 parts by mass of the curable resin composition excluding the thermal conductive material.

[0069] The amount of plasticizer per 100 parts by mass of the total (meth)acrylic polymer in the curable resin composition of this disclosure is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, preferably 100 parts by mass or more, preferably 700 parts by mass or less, more preferably 600 parts by mass or less, even more preferably 500 parts by mass or less, and may be 300 parts by mass or less, from the viewpoint of increasing the flexibility of the heat dissipation material after curing and increasing the conformability of the heat dissipation material to the heat generating element and the heat dissipation material.

[0070] In the curable resin composition of this disclosure, the amount of crosslinking agent per 100 parts by mass of radical polymerizable monomer is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, from the viewpoint of rapidly curing the resin composition at room temperature, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of ensuring the toughness of the crosslinked body of the heat dissipation material. The curable composition of this disclosure preferably contains a total of 100 parts by mass or more of a thermal conductive material per 100 parts by mass of the curable composition of this disclosure, more preferably 200 parts by mass or more, even more preferably 300 parts by mass or more, preferably 1500 parts by mass or less, and more preferably 1200 parts by mass or less.

[0071] When the curable composition of this disclosure is a composition obtained by mixing two liquids, liquid A and liquid B, the mass ratio of liquid A (without the heat conductive material) to liquid B (without the heat conductive material) is preferably 10:90 to 80:20, and more preferably 20:80 to 60:40.

[0072] The curable composition of this disclosure preferably has a monomer conversion rate of 90% or more, more preferably 95% or more, even more preferably 98% or more, and particularly preferably 99% after 48 hours following mixing of each liquid, including liquid A and liquid B, at 25°C. The monomer conversion rate in this disclosure can be determined using gas chromatography or the like. The curable composition of this disclosure may contain organic acid metal salts and organometallic chelate compounds, but it is preferable that they are not included from the viewpoint of solubility in radical polymerizable monomers.

[0073] The content of organic acid metal salts and organometallic chelate compounds in 100 parts by mass of the curable composition of this disclosure is preferably less than 1 part by mass, more preferably less than 0.5 parts by mass, and even more preferably less than 0.3, less than 0.2, and less than 0.1, in that order. Examples of organic acid metal salts and organometallic chelate compounds in this disclosure include cobalt naphthenate, copper naphthenate, manganese naphthenate, cobalt octenoate, copper octenoate and manganese octenoate, copper acetylacetonate, titanium acetylacetonate, manganese acetylacetonate, chromium acetylacetonate, iron acetylacetonate, vanadinyl acetylacetonate and cobalt acetylacetonate. The acid component content in 100 parts by mass of the curable resin composition of this disclosure is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and may be substantially absent.

[0074] <Method of using the curable composition of this disclosure> The curable composition of this disclosure can be cured and form a crosslinked body by mixing the liquids, including liquid A and liquid B. When mixing the liquids containing liquid A and liquid B, a stirring device can be used. Examples of stirring devices include batch mixers, tumblers, Henschel mixers, Banbury mixers, rolls, kneaders, single-screw extruders, and twin-screw extruders, but the present invention is not limited to these examples. The temperature when mixing the liquids containing liquid A and liquid B is not particularly limited, but from the viewpoint of efficiently producing crosslinked materials without using heating devices, cooling devices, etc., it is preferably room temperature. Here, room temperature varies depending on the region and cannot be determined in general terms, but it is usually 0 to 40°C, preferably 0 to 35°C, and more preferably 1 to 30°C. Furthermore, the temperature when mixing the liquids containing liquid A and liquid B may be higher or lower than room temperature as needed, but from the viewpoint of efficiently producing crosslinked materials, it is preferably 0 to 50°C, and may be 0 to 40°C, 0 to 35°C, or 1 to 30°C. Furthermore, the atmosphere when mixing each of the liquids, including liquid A and liquid B, is not particularly limited and may be air. However, from the viewpoint of avoiding the influence of oxygen gas contained in the atmosphere, an inert gas such as nitrogen gas or argon gas may be used.

[0075] When liquids A and B of this disclosure are mixed, the resulting mixture begins to harden, and hardening is usually completed in about 2 to 12 hours at room temperature. The endpoint of the hardening of the mixture can be the tack-free time of the surface of the crosslinked body obtained by the mixture. Tack-free time means the time from the moment liquids A and B are mixed until the mixture no longer adheres to the finger when the surface of the crosslinked body formed by the hardening of the mixture of liquids A and B is touched with a finger that has had oil and grease removed with ethanol or the like.

[0076] <Crosslinked body> The crosslinked body of the present disclosure is a crosslinked body obtained by contacting each of the liquids, including liquid A and liquid B of the curable composition of the present disclosure. More preferably, the crosslinked body is obtained by a step of mixing each of the liquids, including liquid A and liquid B of the curable composition of the present disclosure. The shape of the crosslinked body obtained using the curable resin composition of the present invention is not particularly limited. Examples of the shape of the crosslinked body include sheet-like (film-like), tape-like, cylindrical, and desired molded body shapes, but the present invention is not limited to these shapes. A crosslinked body having a sheet-like or tape-like shape can be manufactured by, for example, mixing each liquid containing liquid A and liquid B, forming a film on a substrate with the resulting mixture using, for example, a brush, bar coater, applicator, air spray, airless spray, roll coater, or flow coater, and curing the formed film; or by mixing each liquid containing liquid A and liquid B, extruding the resulting mixture through a T-die from an extrusion molding machine to form a sheet or film, and curing it. A crosslinked body having a cylindrical shape can be manufactured by, for example, mixing each liquid containing liquid A and liquid B, extruding the resulting mixture through a spider from an extrusion molding machine to form a cylindrical crosslinked body, and curing it. A crosslinked body having the desired shape can be manufactured, for example, by mixing liquids A and B, and then molding the resulting mixture in an injection molding machine or the like to achieve the desired shape.

[0077] <Uses of curable compositions> The curable composition of this disclosure can be used as a raw material for heat dissipators, adhesives, sealants, gap fillers, greases, etc. The crosslinked material of this disclosure has good initial moldability (pot life) and good curability (monomer conversion rate) even at room temperature, and is therefore preferably used as a heat dissipator to release heat generated from heat sources such as automobile batteries and electronic components by interposing it between heat sources such as heat sinks, heat fins, resin films, and metal plates. [Examples]

[0078] The present invention will now be described in more detail based on examples, but the present invention is not limited to such examples.

[0079] Example 1 [Preparation of Solution A] (Meth)acrylic polymer: 2-ethylhexyl / 2-hydroxyethyl acrylate copolymer [2-ethylhexyl / 2-hydroxyethyl acrylate (mass ratio) = 95 / 5, weight-average molecular weight: 250,000, glass transition temperature: approx. -68°C] 2.0g, trimellitic acid ester plasticizer [(Manufactured by ADEKA Corporation, product name: ADEKA Sizer C-880)] 2.8g, 2-ethylhexyl acrylate 4.5g, N,N'-dibutylthiourea [Tokyo Chemical Industries, Ltd.] 0.1g Solution A was prepared by mixing 0 g of 0.10 g of triallyl isocyanurate [manufactured by Shinryo Co., Ltd., trade name: TAIC] and 0.040 g of tris(2-acryloyloxyethyl) isocyanurate [manufactured by Toagosei Co., Ltd., trade name: M-313] as crosslinking agents in air at room temperature (approximately 25°C) until a homogeneous composition was achieved. Further, 40.0 g of alumina powder (average particle size: 10 μm) was added to Solution A and mixed until a homogeneous composition was achieved. The resulting mixture was used as Solution A. [Preparation of Solution B] Solution B was obtained by mixing 1.0 g of 2-ethylhexyl / 2-hydroxyethyl acrylate copolymer [2-ethylhexyl / 2-hydroxyethyl acrylate (mass ratio) = 95 / 5, weight-average molecular weight: 250,000, glass transition temperature: approximately -68°C] as a (meth)acrylic polymer, 2.5 g of trimellitic acid ester plasticizer [manufactured by ADEKA Corporation, product name: Adekasizer C-880], and 0.15 g of cumene hydroperoxide [manufactured by NOF Corporation, product name: Perkmyl H-80] as a polymerization initiator in air at room temperature (approximately 25°C) until a homogeneous composition was achieved. Next, the physical properties of the two-component resin composition for heat dissipation materials, consisting of liquid A and liquid B obtained above, were investigated. The results are shown in Table 1. [Curability] After mixing liquids A and B in air at 25°C, the resulting mixture was allowed to stand for 24 hours. The heat dissipation material formed by curing was then measured for hardness within 1 second using a hardness tester (OO-type durometer (rubber hardness tester, manufactured by Teclock)) in accordance with ASTM D 2240. The sample shape was 100 mm wide x 10 mm deep x 6 mm thick, and the measurements were taken at room temperature. The hardness obtained was calculated by averaging the values ​​measured at 10 locations, and the curability was evaluated based on the following evaluation criteria. (Evaluation Criteria) ◎: Hardness is 20 or higher. ○: Hardness is between 10 and 20. ×: The hardness is less than 10.

[0080] [Monomer conversion rate] After mixing solutions A and B in air at 25°C, the resulting mixture was allowed to stand for 24 hours. 1 g of the heat-dissipating material formed by curing was cut out, 9 g of ethyl acetate and 0.03 g of tridecane as an internal standard were added, and the solution was heated at 50°C for 2 hours while stirring. The solution was then measured by GC to determine the monofunctional monomer conversion rate, and the monomer conversion rate was evaluated based on the following evaluation criteria. (Evaluation Criteria) ◎: The conversion rate of monofunctional monomers is 95% or higher. ○: The conversion rate of monofunctional monomers is 90% or more but less than 95%. ×: The conversion rate of monofunctional monomers is less than 90%.

[0081] [Storage stability] After preparing solutions A and B, they were stored in the dark at 60°C. After two weeks, solutions A and B were mixed and allowed to stand for 24 hours. The resulting heat dissipation material was then tested for hardness within 1 second using a hardness tester (OO-type durometer (rubber hardness tester, manufactured by Teclock)) in accordance with ASTM D 2240. The sample dimensions were 100 mm wide x 10 mm deep x 6 mm thick, and the measurements were taken at room temperature. The hardness was obtained by averaging the values ​​measured at 10 locations, and the storage stability was evaluated based on the following evaluation criteria. (Evaluation Criteria) ◎: The difference in hardness compared to before storage is less than 10. ○: The difference in hardness compared to before storage is 10 or more but less than 15. ×: The difference in hardness compared to before storage is 15 or more.

[0082] Example 2 [Preparation of Solution B] Solution B was obtained by mixing 1.0 g of 2-ethylhexyl / 2-hydroxyethyl acrylate copolymer [2-ethylhexyl / 2-hydroxyethyl acrylate (mass ratio) = 95 / 5, weight-average molecular weight: 250,000, glass transition temperature: approximately -68°C] as a (meth)acrylic polymer, 2.5 g of trimellitic acid ester plasticizer [manufactured by ADEKA Corporation, product name: Adekasizer C-880], and 0.30 g of cumene hydroperoxide [manufactured by NOF Corporation, product name: Perkmyl H-80] as a polymerization initiator in air at room temperature (approximately 25°C) until a homogeneous composition was achieved. Next, the physical properties of the two-component resin composition for heat dissipation, consisting of liquid A obtained in Example 1 and liquid B, were investigated in the same manner as in Example 1. The results are shown in Table 1.

[0083] Example 3 [Preparation of Solution A] (Meth)acrylic polymer: 2-ethylhexyl / 2-hydroxyethyl acrylate copolymer [2-ethylhexyl / 2-hydroxyethyl acrylate (mass ratio) = 95 / 5, weight-average molecular weight: 250,000, glass transition temperature: approx. -68°C] 2.0g, trimellitic acid ester plasticizer [(Manufactured by ADEKA Corporation, product name: ADEKA Sizer C-880)] 3.0g, 2-ethylhexyl acrylate 4.5g, N,N'-dibutylthiourea [Tokyo Chemical Industries, Ltd.] 0.1g Solution A was prepared by mixing 0.08 g of triallyl isocyanurate (manufactured by Shinryo Co., Ltd., trade name: TAIC) and 0.08 g of tris(2-acryloyloxyethyl) isocyanurate (manufactured by Toagosei Co., Ltd., trade name: M-313) as crosslinking agents in air at room temperature (approximately 25°C) until a homogeneous composition was achieved. Further, 40.0 g of alumina powder (average particle size: 10 μm) was added to Solution A and mixed until a homogeneous composition was achieved. The resulting mixture was used as Solution A. Next, the physical properties of the two-component resin composition for heat dissipation, consisting of liquid B obtained in Example 2 and liquid A, were investigated in the same manner as in Example 1. The results are shown in Table 1.

[0084] Comparative Example 1 [Preparation of Solution A] Solution A was prepared by mixing 1.5 g of 2-ethylhexyl / 2-hydroxyethyl acrylate copolymer (2-ethylhexyl / 2-hydroxyethyl acrylate (mass ratio) = 95 / 5, weight-average molecular weight: 250,000, glass transition temperature: approximately -68°C) as a (meth)acrylic polymer, 3.5 g of trimellitic acid ester plasticizer, 4.5 g of 2-ethylhexyl acrylate, 0.10 g of cobalt naphthenate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.10 g of triallyl isocyanurate (manufactured by Shinryo Co., Ltd., trade name: TAIC) and 0.040 g of tris(2-acryloyloxyethyl) isocyanurate in air at room temperature (approximately 25°C) until a homogeneous composition was achieved. Further, 40.0 g of alumina powder (average particle size: 10 μm) was added to Solution A and mixed until a homogeneous composition was achieved. The resulting mixture was used as Solution A. [Preparation of Solution B] Solution B was obtained by mixing 1.0 g of 2-ethylhexyl / 2-hydroxyethyl acrylate copolymer [2-ethylhexyl / 2-hydroxyethyl acrylate (mass ratio) = 95 / 5, weight-average molecular weight: 250,000, glass transition temperature: approximately -68°C] as a meth)acrylic polymer, 2.5 g of trimellitic acid ester plasticizer [manufactured by ADEKA Corporation, product name: Adekasizer C-880], and 0.30 g of benzoyl peroxide [manufactured by NOF Corporation, product name: Niper NS] as a polymerization initiator in air at room temperature (approximately 25°C) until a homogeneous composition was achieved. Next, the physical properties of the two-component resin composition for heat dissipation material, consisting of liquid A and liquid B obtained in Comparative Example 1, were investigated in the same manner as in Example 1. The results are shown in Table 1.

[0085] [Table 1]

[0086] *Comparative Example 1 showed uneven curing. The results shown in Table 1 indicate that each example exhibits a short pot life, excellent curability and monomer conversion rate, and high storage stability. [Industrial applicability]

[0087] The two-component resin composition for heat dissipation materials of the present invention is useful, for example, in applications where it is interposed between a heat-generating element such as an electrical component or electronic component such as an automobile battery and a heat-dissipating material such as a heat sink, heat-dissipating fin, resin film, or metal plate to dissipate heat generated from the heat-generating element.

Claims

1. A curable resin composition that hardens when liquid A and liquid B are mixed, Solution A contains a thiourea compound represented by general formula (1) in an amount of 0.20 parts by mass to 1.50 parts by mass per 100 parts by mass of the curable resin composition excluding the thermal conductive material, an alkyl (meth)acrylate monomer having an alkyl group with 1 to 18 carbon atoms in an amount of 15 parts by mass to 50 parts by mass per 100 parts by mass of the curable resin composition excluding the thermal conductive material, and a crosslinking agent in an amount of 0.01 parts by mass to 10 parts by mass per 100 parts by mass of the radical polymerizable monomer in the curable resin composition, and Solution B contains a hydroperoxide compound. The mass ratio of the thiourea compound to the hydroperoxide compound (mass of thiourea compound / mass of hydroperoxide compound) is between 11 / 89 and 60 / 40. Liquids A and B contain trimellitic acid ester and a polymer that is a (meth)acrylic polymer containing 0.3 to 30 parts by mass of structural units derived from hydroxyl group-containing (meth)acrylate in 100 parts by mass of (meth)acrylic monomer, in a curable resin composition excluding thermal conductive materials, in an amount of 6 to 35 parts by mass. Curable resin composition. (In the formula, R1, R2, R3, and R4 represent hydrogen, an alkyl group having 1 to 20 carbon atoms, a phenyl group, a tolyl group, a methoxyphenyl group, or a naphthyl group.)

2. A cured product obtained by curing the curable resin composition described in claim 1.

3. A curable resin composition for a heat dissipation material using the curable resin composition described in claim 1.

4. A method for producing a curable resin composition by mixing liquid A and liquid B, Solution A contains a thiourea compound represented by general formula (1) in an amount of 0.20 parts by mass to 1.50 parts by mass per 100 parts by mass of the curable resin composition excluding the thermal conductive material, an alkyl (meth)acrylate monomer having an alkyl group with 1 to 18 carbon atoms in an amount of 15 parts by mass to 50 parts by mass per 100 parts by mass of the curable resin composition excluding the thermal conductive material, and a crosslinking agent in an amount of 0.01 parts by mass to 10 parts by mass per 100 parts by mass of the radical polymerizable monomer in the curable resin composition, and Solution B contains a hydroperoxide compound. The mass ratio of the thiourea compound to the hydroperoxide compound (mass of thiourea compound / mass of hydroperoxide compound) is between 11 / 89 and 60 / 40. Liquids A and B contain trimellitic acid ester and a polymer that is a (meth)acrylic polymer containing 0.3 to 30 parts by mass of structural units derived from hydroxyl group-containing (meth)acrylate in 100 parts by mass of (meth)acrylic monomer, in a curable resin composition excluding thermal conductive materials, in an amount of 6 to 35 parts by mass. A method for producing a curable resin composition. (In the formula, R1, R2, R3, and R4 represent hydrogen, an alkyl group having 1 to 20 carbon atoms, a phenyl group, a tolyl group, a methoxyphenyl group, or a naphthyl group.)

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