Curable resin composition and gap filler

Abstract

To provide a curable resin composition which contains a non-silicone-based resin, is excellent in high thermal conductivity, and contributes to low viscosity and low wear property.SOLUTION: A curable resin composition contains an acrylic resin, a first inorganic filler, and a second inorganic filler, wherein the second inorganic filler is surface-coated with zinc molybdate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition and a gap filler. [Background technology]

[0002] In recent years, with the miniaturization and high performance of electronic devices, heat dissipation measures for electronic devices have become an issue, and the development of various thermally conductive materials is progressing. The thermally conductive materials being developed can be broadly divided into fillers and resins, with alumina and magnesium oxide being well known as fillers, and silicone-based resins being well known as resins due to their excellent heat resistance (see Patent Document 1).

[0003] However, silicone-based resins are likely to generate organic silicone gases, which can cause problems with electrical contacts in electronic devices, so there is a need to develop non-silicone resins that do not generate organic silicone gases.

[0004] Therefore, Patent Document 2 reports a composition for a thermally conductive material that includes an acrylic polymer having a crosslinkable functional group, an anti-dripping agent, and a thermally conductive filler. It discloses that the acrylic polymer uses a combination of an acrylic polymer having crosslinkable functional groups at both ends and an acrylic polymer having a crosslinkable functional group at only one end. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-242022 [Patent Document 2] Japanese Patent Application Publication No. 2018-204003 Summary of the Invention [Problem to be solved by the invention]

[0006] Thermally conductive materials can be used for a variety of purposes, including sheets, potting, adhesives, greases, and gap fillers. However, with the shift to electric vehicles, there is growing demand for gap fillers, which offer superior performance and reliability.

[0007] The thermally conductive material composition described in Patent Document 2 had difficulty in achieving the high thermal conductivity required for recent gap fillers. Furthermore, the addition of tetrafluoroethylene resin as an anti-dripping agent is disclosed, but tetrafluoroethylene resin has low polarity and separates over time, so it was necessary to increase the viscosity.

[0008] Furthermore, because gap fillers are applied using a dispenser, high viscosity significantly affects dischargeability. Furthermore, the large amount of abrasive, thermally conductive inorganic filler contained in the gap filler causes severe wear on the equipment. Therefore, there is a need for a gap filler that has low viscosity to achieve high dischargeability and low wear to reduce running costs. Patent Document 2 requires high viscosity, which makes the gap filler insufficient in terms of dischargeability.

[0009] However, the composition described in Patent Document 1 still has a high viscosity and uses a thermally conductive inorganic filler with a Mohs hardness of 6 or more, which results in high abrasion. Patent Document 2 only uses commonly known materials as thermally conductive fillers, and insufficient consideration has been given to abrasion resistance.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a curable resin composition that contains a non-silicone resin, has excellent high thermal conductivity, and contributes to low viscosity and low wear. [Means for solving the problem]

[0011] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a resin composition containing an inorganic filler whose surface is coated with a specific substance.

[0012] (1) A curable resin composition comprising an acrylic resin, a first inorganic filler, and a second inorganic filler, wherein the second inorganic filler is surface-coated with zinc molybdate. (2) The curable resin composition according to (1) above, wherein the first inorganic filler is aluminum nitride. (3) The curable resin composition according to (1) or (2) above, wherein the first inorganic filler is spherical or approximately spherical. (4) The curable resin composition according to any one of (1) to (3) above, wherein the acrylic resin contains at least both a non-functional acrylic resin and a mono- or higher functional acrylic resin. (5) The curable resin composition according to any one of (1) to (4) above, further comprising a plasticizer, the plasticizer including at least one selected from the group consisting of phthalic acid plasticizers, adipic acid plasticizers, ester plasticizers, epoxy plasticizers, and combinations thereof. (6) The curable resin composition according to any one of the above (1) to (5), wherein the second inorganic filler is talc surface-coated with zinc molybdate. (7) A gap filler comprising the curable resin composition according to any one of (1) to (6) above. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a curable resin composition and a gap filler that have reduced abrasion, low viscosity, and high thermal conductivity. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail.

[0015] [Curable resin composition] The curable resin composition of the present invention is characterized by containing an acrylic resin, a first inorganic filler, and a second inorganic filler, and the second inorganic filler is surface-coated with zinc molybdate.

[0016] (acrylic resin) The acrylic resin of the present invention is not particularly limited, and either a mono- or higher functional acrylic resin or a non-functional acrylic resin can be used. From the viewpoint of flexibility and low viscosity of the obtained cured product, it is more preferable to contain at least both a mono- or higher functional acrylic resin and a non-functional acrylic resin.

[0017] [Monofunctional or higher acrylic resin] Examples of monofunctional or higher acrylic resins include bisphenol FEO-modified (n=2 to 50) diacrylate, bisphenol AEO-modified (n=2 to 50) diacrylate, bisphenol SEO-modified (n=2 to 50) diacrylate, bisphenol FEO-modified (n=2 to 50) dimethacrylate, bisphenol AEO-modified (n=2 to 50) dimethacrylate, bisphenol SEO-modified (n=2 to 50) Dimethacrylate, 1,6-Hexanediol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, tetramethylolpropane tetraacrylate, tetraethylene glycol diacrylate, 1,6-Hexanediol dimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, pentaerythritol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethacrylate, tetramethylolpropane tetramethacrylate, tetraethylene glycol dimethacrylate, methoxydiethylene glycol methacrylate, methoxypoly Ethylene glycol methacrylate, β-methacryloyloxyethyl hydrogen phthalate, β-methacryloyloxyethyl hydrogen succinate, 3-chloro-2-hydroxypropyl methacrylate, stearyl methacrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol acrylate, β-acryloyloxyethyl hydrogen succinate, lauryl acrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2-hydroxy-1,3-dimethacryloxypropane, 2,2-Bis[4-(methacryloxyethoxy)phenyl]propane, 2,2-bis[4-(methacryloxydiethoxy)phenyl]propane, 2,2-bis[4-(methacryloxypolyethoxy)phenyl]propane, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 2,2-bis[4-(acryloxydiethoxy)phenyl]propane, 2,2-bis[4-(acryloxypolyethoxy)phenyl]propane, 2-hydroxy-1-acryloxy-3-methacryloyl Oxypropane, trimethylolpropane trimethacrylate, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, methoxydipropylene glycol methacrylate, methoxytriethylene glycol acrylate, nonylphenoxy polyethylene glycol acrylate, nonylphenoxy polypropylene glycol acrylate, 1-acryloyloxypropyl-2-phthalate, isostearyl acrylate, polyoxyethylene alkyl ether acrylate, nonylphenoxy ethylene glycol acrylate acrylate, polypropylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 1,6-mexanediol dimethacrylate, 1,9-nonanediol methacrylate, 2,4-diethyl-1,5-pentanediol dimethacrylate, 1,4-cyclohexanedimethanol dimethacrylate, dipropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, 2,2-hydrogenated bis[4-(acryloxypolyethoxy)phenyl]propane, 2,2-bis [4-(acryloxypolypropoxy)phenyl]propane, 2,4-diethyl-1,5-pentanediol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, isocyanuric acid tri(ethane acrylate), pentasritol tetraacrylate, ethoxylated pentasritol tetraacrylate, propoxylated pentasritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol polyacrylate, triallyl isocyanurate,Examples of such an alkyl acrylate include glycidyl methacrylate, glycidyl allyl ether, 1,3,5-triacryloylhexahydro-s-triazine, triallyl 1,3,5-benzenecarboxylate, triallylamine, triallyl citrate, triallyl phosphate, allobarbital, diallylamine, diallyldimethylsilane, diallyl disulfide, diallyl ether, zallyl sialate, diallyl isophthalate, diallyl terephthalate, 1,3-diallyloxy-2-propanol, diallyl sulfide diallyl maleate, 4,4'-isopropylidenediphenol dimethacrylate, 4,4'-isopropylidenediphenol diacrylate, and copolymers thereof.

[0018] The monofunctional or higher functional acrylic resin may be a urethane (meth)acrylate resin, an epoxy (meth)acrylate resin, a polyester (meth)acrylate resin, an acrylic (meth)acrylate resin, an unsaturated polyester resin, or the like.

[0019] Commercially available urethane (meth)acrylate resins include, for example, HA4861, HA7902-1, and HA7909-1 (Resonac Co., Ltd.), Aronix M-1100 and M-1200 (Toagosei Co., Ltd.), EBECRYL204, EBECRYL205, EBECRYL210, EBECRYL215, EBECRYL220, EBECRYL230, EBECRYL244, EBECRYL245, and EBECRYL264. , EBECRYL265, EBECRYL270, EBECRYL280 / 15IB, EBECRYL284, EBECRYL285, EBECRYL294 / 25HD, EBECRYL1259, EBECRYL12 90, EBECRYL4491, EBECRYL4820, EBECRYL4858, EBECRYL5129, EBECRYL8210, EBECRYL8254, EBECRYL8301R, EBECRYL830 7, EBECRYL8402, EBECRYL8405, EBECRYL8411, EBECRYL8413, EBECRYL8465, EBECRYL8800, EBECRYL8804, EBECRYL8807 , EBECRYL9260, EBECRYL9270, EBECRYL8311, EBECRYL8701, EBECRYL9227EA, KRM8528, KRM8667, KRM8904, KRM8452, KRM 8296, KRM7735, KRM8200 (Daicel-Allnex Co., Ltd.), UV-3610ID80, UV-3640PE80, UV-3630ID80, UV-2000B, UV-2750B, UV-3000B, UV-3200B, UV-3210EA, UV-__3300B, UV-3310B, UV-3500BA, UV-3520TL, UV-3700B, UV-6640B (Mitsubishi Chemical Corporation), LUXYDIR V-4000BA, LUXYDIR V-4221, LUXYDIRRC29-124 (DIC Corporation), AH-600, AT-600, UA-306H, UA-306T, UA-306I, UA-510H, UF-8001G (Kyoeisha Chemical Co., Ltd.), KAYARADUX-3204, UX-4101, UXT-6100, UX-6101, UX-7101, UX-8101, UX-0937, UXF-4002, DPHA-40H, UX-500, UX-5005 (Nippon Kayaku Co., Ltd.), Art Resin UN-333, UN-350, UN-1255, UN-2600, UN-2700, UN-5500, UN-5590, UN-5507, UN- 6060PTN, UN-6200, UN-6202, UN-6300, UN-6301, UN-7600, UN-7700, UN-9000PE, UN-9200A (Negami Chemical Industrial Co., Ltd.), GENOMER4188 / EHA, GENOMER4215, GENOMER4217, GENOMER4230, GENOMER4267, GENOMER4269 / M22, GENOMER4205, GENOMER4256, GENOMER4297, GENOMER4302, GENOMER4425, GENOMER4622, GENOMER4690 (RAHN), and the like.

[0020] Commercially available epoxy (meth)acrylate resins include, for example, HA7851, HA7663 (Resonac Co., Ltd.), EBECRYL645, EBECRYL648, EBECRYL860, EBECRYL1606, EBECRYL3500, EBECRYL3603, EBECRYL3608, EBECRYL3700, EBECRYL3701, EBECRYL3702, EBECRYL3703, EB Examples include ECRYL3708 (Daicel-Allnex Co., Ltd.), Unidic 5500, Unidic 5502 (DIC Corporation), KAYARA DR-115, R-130, R-388, EAM-2160 (Nippon Kayaku Co., Ltd.), GENOMER 2235, GENOMER 2252, GENOMER 2263, GENOMER 2253, GENOMER 2255, GENOMER 2259 (RAHN), and the like.

[0021] Commercially available examples of the acrylic (meth)acrylate resin include HA7975, HA7988, and HA7975D (Resonac Inc.), UV-NS001, UV-NS034, UV-NS054, UV-NS063, and UV-NS077 (Mitsubishi Chemical Corporation), Unidic V-6840, Unidic V-6841, Unidic WHV-649, and Unidic EKS-675 (DIC Corporation), Macromonomer A-AB-6 (Toagosei Co., Ltd.), RC-100C, RC-110C, and MM-110C (Kaneka Corporation).

[0022] Commercially available examples of the polyester (meth)acrylate resin include Aronix M-6100, M-6200, M-6250, M-6500, M-7100, M-8100, and M-9050 (Toagosei Co., Ltd.), EBECRYL811, EBECRYL812, EBECRYL851, EBECRYL852, EBECRYL884, and EBECRYL885 (Daicel-Allnex Corporation), and GENOMER3364, GENOMER3414, GENOMER3485, GENOMER3497, and GENOMER3611 (RAHN).

[0023] In this embodiment, it is more preferable to use a difunctional acrylic resin having a terminal functional group in combination with a monofunctional acrylic resin. For example, the difunctional acrylic resin may be selected from M-1100, M-1200, UN-6200, RC100C, and RC110C, and the monofunctional acrylic resin may be selected from MM110C, M-5400, M120, M-460, M-5300, M-5700, and AB-6.

[0024] The monofunctional or higher acrylic resin has an average of one or more (meth)acryloyl groups per molecule, and of these, an average of 0.8 or more at the molecular terminals, preferably an average of one or more at the molecular terminals per molecule. From the viewpoint of crosslinking, the average number of (meth)acryloyl groups per molecule is preferably 1.0 or more, more preferably 1.1 or more. From the viewpoint of flexibility of the resulting cured product, the upper limit is preferably 2.5 or less per molecule.

[0025] On average, 0.8 or more (meth)acryloyl groups are present at the molecular terminals, but the positions of the other (meth)acryloyl groups are not particularly limited. In order to increase the distance between crosslinking points, it is preferable that all of the (meth)acryloyl groups are located near the molecular terminals, and it is particularly preferable that all of the (meth)acryloyl groups are located at the molecular terminals.

[0026] The viscosity (25°C) of the monofunctional or higher acrylic resin is not particularly limited as long as it does not impair the object of the present invention, but is preferably 500 Pa·s or less, more preferably 200 Pa·s or less, for example.

[0027] [Non-functional acrylic resin] The non-functional acrylic resin is an acrylic resin that does not have a functional group such as a hydroxyl group in the molecule, and is preferably a liquid having a molecular weight of 500 to 3,000, more preferably a liquid having a molecular weight of 750 to 2,500. Non-functional acrylic resins are preferred because they act as a kind of plasticizer and provide flexibility when cured.

[0028] Examples of raw material monomers for non-functional acrylic resins include monomers such as methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, methoxyethyl (meth)acrylate, and ethoxyethyl (meth)acrylate. These monomers may be used alone or in combination of two or more. These monomers can be added in the presence of a catalyst such as a radical to form an acrylic resin by a conventional method. As the non-functional acrylic resin of the present invention, a liquid substance with a relatively small molecular weight is preferably used. As such a non-functional acrylic resin, the commercially available ARUFON (manufactured by Toagosei Co., Ltd.) UP-1000 series can be preferably used.

[0029] The blending ratio (by mass) of the monofunctional or higher acrylic resin to the non-functional acrylic resin is not particularly limited, but is preferably 30:70 to 70:30, and more preferably 35:65 to 60:40. A ratio within this range is preferable because the resulting resin composition has excellent flexibility and can suppress bleeding.

[0030] (First inorganic filler) In the present invention, the first inorganic filler is not particularly limited, and examples thereof include metals such as gold, silver, copper, and alloys thereof; metal oxides such as alumina, titanium oxide, magnesium oxide, and silica; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; metal carbonates such as calcium carbonate and magnesium carbonate; metal nitrides such as aluminum nitride, boron nitride, and silicon nitride; and silicates such as aluminosilicates, talc, mica, and glass. From the viewpoints of high thermal conductivity and low Mohs hardness, examples include zinc oxide, aluminum hydroxide, magnesium hydroxide, aluminosilicates, talc, etc. From the viewpoints of chemical stability, high thermal conductivity, and low Mohs hardness, aluminum nitride, alumina, and magnesium carbonate are preferred, and aluminum nitride is particularly preferred.

[0031] The first inorganic filler may be used alone or in combination of two or more. When two or more types are used in combination, different filler types can be used so as to obtain properties according to the application. For example, aluminum hydroxide or alumina can be blended to improve thermal conductivity.

[0032] The shape of the first inorganic filler is not particularly limited, and examples thereof include plate-like, spherical, polyhedral, and card-house-like shapes (aggregates of multiple plate-like particles). From the viewpoint of further improving thermal conductivity, however, a spherical or nearly spherical shape is preferable.

[0033] In this specification, the term "spherical" or "approximately spherical" refers to an average circularity of 0.85 or more. The method for measuring the average circularity is not particularly limited, but it can be calculated, for example, by the following method. <Average circularity> The first inorganic filler is fixed with carbon tape and then coated with osmium. The particles are then photographed at a magnification of 500 to 50,000 times using a scanning electron microscope (manufactured by JEOL Ltd., product name: JSM-7001F SHL). The projected area (S) and projected perimeter (L) of the particles are calculated using an image analyzer (manufactured by Nippon Roper Co., Ltd., product name: Image-Pro Premier Ver. 9.3). The circularity is then calculated using the following formula: The circularity of any 200 particles is calculated, and the average value is taken as the average circularity. Circularity = 4πS / L 2

[0034] The average particle diameter (D50) of the first inorganic filler is not particularly limited, but is preferably 0.001 μm to 100 μm, more preferably 0.01 μm to 50 μm, and particularly preferably 0.1 μm to 30 μm. The average particle diameter (D50) can be measured by a laser diffraction / scattering particle size distribution measurement method.

[0035] The first inorganic filler may be coated with zinc molybdate, as with the second inorganic filler described below. From the viewpoint of ensuring thermal conductivity, an inorganic filler that is not surface-coated with zinc molybdate is preferred.

[0036] The content of the first inorganic filler may be 50 to 95 mass %, preferably 70 to 95 mass %, and particularly preferably 85 to 95 mass %, when the resin composition (solid content) is taken as 100 mass %. Within this range, the resulting resin composition has excellent thermal conductivity, which is preferable.

[0037] (Second inorganic filler) The second inorganic filler of the present invention is not particularly limited, but is at least surface-coated with zinc molybdate.

[0038] In this specification, "surface coating" more specifically means that zinc molybdate is supported on the particle surface. The state of support may be either that the zinc molybdate is supported on the entire particle without gaps, or that the zinc molybdate is supported only partially.

[0039] Examples of the second inorganic filler include metals such as gold, silver, copper, and alloys thereof; metal oxides such as alumina, titanium oxide, magnesium oxide, and silica; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; metal carbonates such as calcium carbonate and magnesium carbonate; metal nitrides such as aluminum nitride, boron nitride, and silicon nitride; and silicates such as talc, mica, and glass. From the viewpoints of high thermal conductivity and low Mohs hardness, zinc oxide, aluminum hydroxide, magnesium hydroxide, and talc are preferred, and talc is particularly preferred.

[0040] The content of the second inorganic filler may be 0.01 to 15 mass%, preferably 0.025 to 10 mass%, and particularly preferably 0.05 to 7 mass%, when the resin composition (solid content) is taken as 100 mass%. Within this range, the resulting resin composition has excellent thermal conductivity, which is preferable.

[0041] When the first inorganic filler and the second inorganic filler are used in combination, the blending ratio of the first inorganic filler to the second inorganic filler is preferably 85.0:15.0 to 99.99:0.01, more preferably 92.5:7.5 to 99.9:0.1, even more preferably 95.0:5.0 to 99.7:0.3, and particularly preferably 97.5:2.5 to 99.5:0.5.

[0042] The total content of the first inorganic filler and the second inorganic filler may be 50 to 95 mass%, preferably 70 to 95 mass%, and particularly preferably 85 to 95 mass%, when the resin composition (solid content) is 100 mass%.

[0043] (plasticizer) The resin composition of the present invention may further contain a plasticizer. The plasticizer is at least one selected from the group consisting of phthalic acid plasticizers, trimellitic acid plasticizers, adipic acid plasticizers, ester plasticizers, epoxy plasticizers, and combinations thereof. From the viewpoint of bleedlessness during heat resistance and durability tests, a highly compatible and heat-resistant plasticizer is preferred. Examples of the phthalic acid plasticizer include phthalic acid diester, diisononyl phthalate, diisodecyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, dibutyl phthalate, and dihexyl phthalate. Examples of the trimellitic acid plasticizer include trimellitic acid esters and trimellitic acid long-chain alkyl esters. Examples of the adipic acid plasticizer include adipic acid esters and adipic acid polyesters such as dioctyl adipate, diisononyl adipate, diisodecyl adipate, dibutoxyethyl adipate, and bis(butyltriglycol) adipate. Examples of the ester-based plasticizer include di-(2-ethylhexyl) adipate, di-(2-ethylhexyl) azelate, dibutyl sebacate, and pyromellitic acid long-chain alkyl ester. Examples of the epoxy plasticizer include epoxidized linseed oil and liquid epoxy resin.

[0044] Examples of the trimellitic acid ester include trimethyl trimellitate, triethyl trimellitate, tri-n-propyl trimellitate, tri-n-butyl trimellitate, tri-n-pentyl trimellitate, tri-n-hexyl trimellitate, tri-n-heptyl trimellitate, tri-n-octyl trimellitate, tri-n-nonyl trimellitate, tri-n-decyl trimellitate, tri-n-undecyl trimellitate, tri-n-dodecyl trimellitate, and tri-n-pentyl trimellitate. Linear trimellitic acid esters in which the alkyl group constituting the ester is linear, such as n-tridecyl, tri-n-tetradecyl trimellitate, tri-n-pentadecyl trimellitate, tri-n-hexadecyl trimellitate, tri-n-heptadecyl trimellitate, tri-n-stearyl trimellitate, and tri-n-alkyl trimellitate (wherein the number of carbon atoms in the alkyl groups of the trimellitic acid tri-n-alkyl esters may be different from each other in one molecule); Examples of the trimellitic acid ester include branched trimellitic acid esters in which the alkyl group constituting the ester is branched, such as tri-i-propyl trimellitate, tri-i-butyl trimellitate, tri-i-pentyl trimellitate, tri-i-hexyl trimellitate, tri-i-heptyl trimellitate, tri-i-octyl trimellitate, tri-(2-ethylhexyl) trimellitate, tri-i-nonyl trimellitate, tri-i-decyl trimellitate, tri-i-undecyl trimellitate, tri-i-dodecyl trimellitate, tri-i-tridecyl trimellitate, tri-i-tetradecyl trimellitate, tri-i-pentadecyl trimellitate, tri-i-hexadecyl trimellitate, tri-i-heptadecyl trimellitate, tri-i-octadecyl trimellitate, and trialkyl trimellitate (wherein the number of carbon atoms in the alkyl group of the trialkyl trimellitate may be different from each other in one molecule).

[0045] The content of the plasticizer is, for example, preferably 30 to 60% by mass, and more preferably 40 to 55% by mass, relative to 100% by mass of the resin component, since the heat resistance and flexibility of the resulting resin composition are improved when the content is within this range.

[0046] (Other ingredients) The resin composition of the present invention may contain a crosslinking agent, a dispersant, a curing agent, a coupling agent, a surfactant, an antioxidant, an ultraviolet absorber, etc., within the range that does not impair the effects of the invention.

[0047] There are no limitations on the crosslinking agent as long as it generates radicals, but organic peroxides that generate free radicals when exposed to heat are particularly preferred.

[0048] Organic peroxides include isobutyl peroxide, α,α'-bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate, di-n-propyl peroxydicarbonate, di-s-butyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, di-2-ethoxyethyl peroxydicarbonate, di(ethylhexyl)peroxydicarbonate, t-hexyl peroxyneodecanoate, dimethoxybutyl peroxydicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, t-butyl peroxyneodecanoate, and t-hexyl peroxypivalate. ester, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoyl)hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m-butylbenzoyl peroxide, benzoyl peroxide, t-butylperoxyisobutyrate, 1,1-bis(t-butylperoxy)2-methylcyclohexane, 1,1-bis(t-hexylperoxy)-3, 3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexanone, 2,2-bis(4,4-dibutylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(m-toluoylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl carbonate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, 2,2-bis(t-butylperoxy)butane, t-butylperoxybenzoate, n-butyl-4,4-bis(t-butylperoxy)valerate, di-t-butylperoxyisophthalate, α,α'-bis(t-butylperoxy)diisopropyl benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane Examples of organic peroxides include benzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, and lauroyl peroxide. Among these, from the viewpoint of reactivity, the organic peroxide is preferably at least one compound selected from the group consisting of benzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, and cumene hydroperoxide.

[0049] Examples of dispersants include phosphate esters, ethylhexyl acrylate, triphenylphosphine, alkylammonium salts, and 1-methoxy-2-propyl acetate.

[0050] Among these, phosphate esters are preferred because they have a high affinity with inorganic fillers and can reduce viscosity, such as Disparlon DA-375 (manufactured by Kusumoto Chemicals Co., Ltd.), Plysurf A208N (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Phosphanol RL-210 (manufactured by Toho Chemical Industry Co., Ltd.), Phosphanol RS-710 (manufactured by Toho Chemical Industry Co., Ltd.), Phosphanol RS-410 (manufactured by Toho Chemical Industry Co., Ltd.), and BYK W-9010 (manufactured by BYK).

[0051] The curing agent is preferably a compound that exhibits curing ability by light or heat, and examples thereof include peroxides such as bis(4-tert-butylcyclohexan-1-yl) peroxydicarbonate and benzoyl peroxide.

[0052] Examples of the coupling agent include (meth)acryloyloxy-based silane coupling agents, acryloxy-based silane coupling agents, vinyl-based silane coupling agents, epoxy-based silane coupling agents, amino-based silane coupling agents, and ureido-based silane coupling agents.

[0053] Examples of the (meth)acryloyloxy-based silane coupling agent include 3-(meth)acryloyloxypropyltrimethylsilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, and 3-(meth)acryloyloxypropyltriethoxysilane.

[0054] Examples of the acryloxy-based silane coupling agent include 3-acryloxypropyltrimethoxysilane.

[0055] Examples of the vinyl-based silane coupling agent include allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane.

[0056] Examples of the epoxy-based silane coupling agent include diethoxy(glycidyloxypropyl)methylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. Examples of the styrene-based silane coupling agent include p-styryltrimethoxysilane.

[0057] Examples of the amino-based silane coupling agent include N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane.

[0058] An example of the ureido-based silane coupling agent is 3-ureidopropyltriethoxysilane. An example of a chloropropyl-based silane coupling agent is 3-chloropropyltrimethoxysilane. An example of a mercapto-based silane coupling agent is 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane. An example of a sulfide-based silane coupling agent is bis(triethoxysilylpropyl)tetrasulfide. An example of an isocyanate-based silane coupling agent is 3-isocyanatepropyltriethoxysilane. An example of an aluminum-based coupling agent is acetoalkoxyaluminum diisopropylate.

[0059] These silane coupling agents may be used alone or in combination of two or more. Among them, those having a (meth)acryloyloxy group, a glycidyl group, or an epoxycyclohexyl group are preferred, and 3-(meth)acryloyloxypropyltrimethoxysilane is most preferred. A specific example of the silane coupling agent is KBE-502 manufactured by Shin-Etsu Chemical Co., Ltd.

[0060] The content of other components is preferably 0.1 to 5% by mass, and more preferably 0.1 to 3% by mass, when the resin composition (solid content) is taken as 100% by mass.

[0061] The resin composition in this embodiment is preferably liquid and has a viscosity at 25°C in the range of 50 Pa·s to 2,000 Pa·s, more preferably 100 Pa·s to 1,000 Pa·s, even more preferably 100 Pa·s to 450 Pa·s, and particularly preferably 100 Pa·s to 400 Pa·s. Having a viscosity in this range that forms a non-flowable reaction product after application to a substrate makes the composition suitable for application to a substrate using a dispenser or the like.

[0062] [Application] The resin composition of the present invention has excellent thermal conductivity and can be widely used as a heat dissipation material in electrical and electronic components, semiconductor elements, etc., but it is particularly suitable for use as a gap filler because of its low abrasion resistance and low viscosity. [Example]

[0063] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0064] [Examples 1 to 9, Comparative Examples 1 and 2] Resin compositions were obtained by mixing an acrylic resin, a crosslinking agent, a plasticizer, a coupling agent, a first inorganic filler, and a second inorganic filler in the proportions shown in Tables 1 and 2 (the resin components and inorganic fillers were each prepared to be 100 parts by mass according to the proportions, and then mixed according to the proportions). The inorganic fillers used in the FAN series, DAW series, and AO series were all spherical.

[0065] [Evaluation method] The resulting resin compositions were evaluated according to the following methods.

[0066] (thermal conductivity) Each of the obtained resin compositions was poured into a mold and cured at 70°C for 3 hours to obtain a sheet of cured material having a thickness of 1 mm. The thermal diffusivity and specific heat of the cured sheet were measured at 25°C using a thermal conductivity measuring device (LFA467 HyperFlash, manufactured by NETZSCH). The density of the heat dissipation member was then measured using the Archimedes method. The thermal conductivity of the heat dissipation member was estimated from the product of the obtained thermal diffusivity, specific heat, and density.

[0067] (wear resistance) Each resin composition was cured to a thickness of 1.6 mm, and 2,000 holes were drilled using a drill (0.3 mm diameter) at 150,000 rpm. The wear rate of the drill bit was then evaluated as the ratio (percentage) of the area of ​​the drill bit worn by drilling to the area of ​​the drill bit before drilling. The wear resistance was evaluated according to the following criteria. ◎: Less than 5% 〇: 5% or more but less than 10% △: 10% to less than 20% ×: 20% or more

[0068] (viscosity measurement) The viscosity of the resulting resin composition was measured using an E-type viscometer TVE-20H (manufactured by Toki Sangyo Co., Ltd.) under conditions of viscosity (25° C.) and a rotation speed of 3 rpm.

[0069] [Table 1]

[0070] [Table 2]

Claims

1. A curable resin composition comprising an acrylic resin, a first inorganic filler, and a second inorganic filler, wherein the second inorganic filler is surface-coated with zinc molybdate.

2. The curable resin composition according to claim 1 , wherein the first inorganic filler is aluminum nitride.

3. The curable resin composition according to claim 2 , wherein the aluminum nitride is spherical or approximately spherical.

4. The curable resin composition according to claim 1 , wherein the acrylic resin comprises at least both a non-functional acrylic resin and a mono- or higher functional acrylic resin.

5. 2. The curable resin composition according to claim 1, further comprising a plasticizer, wherein the plasticizer comprises at least one selected from the group consisting of a phthalic acid-based plasticizer, an adipic acid-based plasticizer, an ester-based plasticizer, an epoxy-based plasticizer, and a combination thereof.

6. The curable resin composition according to claim 1 , wherein the second inorganic filler is talc surface-coated with zinc molybdate.

7. A gap filler comprising the curable resin composition according to any one of claims 1 to 5.

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