Heat dissipation resin composition

Abstract

The present disclosure addresses the problem of providing a heat dissipation resin composition having excellent life while having good low temperature curability. A heat dissipation resin composition according to the present disclosure contains an epoxy resin (A), a curing agent (B), and an inorganic filler (C). The curing agent (B) contains an ionic liquid compound. The ionic liquid compound contains a cation part and an anion part. The cation part contains imidazolium cation, and the anion part contains at least one selected from the group consisting of dicyanamide anion, thiocyanate anion, and trifluoroacetate anion.

Description

Heat-dissipating resin composition

[0001] The present disclosure relates to a heat-dissipating resin composition, and more particularly to a heat-dissipating resin composition containing an epoxy resin and a curing agent.

[0002] In recent years, with the miniaturization and high performance of electric and electronic components, heat dissipation measures that effectively dissipate heat generated in electric and electronic components to the outside in a small space have become extremely important. To address this heat dissipation measure, heat-dissipating resin compositions that can increase the thermal conductivity of the cured product have been studied. Recently, heat-dissipating resin compositions are required to have good low-temperature curing properties that allow them to be cured at relatively low temperatures and to produce uniform cured products so that they can be used for components with low heat resistance.

[0003] As an example of a heat-dissipating resin composition that can be used, Patent Document 1 discloses a thermosetting resin composition that contains an anionic polymerizable compound, an anionic polymerizable curing agent, and an ionic liquid, wherein the anionic polymerizable compound is liquid at 60°C, the ionic liquid has a cation that is an imidazolium salt, a pyridinium salt, or a phosphonium salt, and the blending ratio (weight ratio) of the ionic liquid to the anionic polymerizable curing agent is 1.1 or more and 5.0 or less.

[0004] Such a resin composition is required to have not only good low-temperature curing properties but also good life and be resistant to deterioration over time, such as thickening, etc. However, the conventional resin compositions described above have not been able to achieve both good low-temperature curing properties and a long life.

[0005] JP 2019-014781 A

[0006] An object of the present disclosure is to provide a heat-dissipating resin composition that has good low-temperature curing properties and an excellent life.

[0007] A heat-dissipating resin composition according to one embodiment of the present disclosure includes an epoxy resin (A), a curing agent (B), and an inorganic filler (C), wherein the curing agent (B) includes an ionic liquid compound, the ionic liquid compound includes a cation moiety and an anion moiety, the cation moiety includes an imidazolium cation, and the anion moiety includes at least one anion selected from the group consisting of a dicyanamide anion, a thiocyanate anion, and a trifluoroacetate anion.

[0008] 1. Overview The heat-dissipating resin composition according to this embodiment (hereinafter also referred to as composition (X)) contains an epoxy resin (A), a curing agent (B), and an inorganic filler (C). The curing agent (B) contains an ionic liquid compound (hereinafter also referred to as ionic liquid compound (B1)). The ionic liquid compound (B1) contains a cation moiety and an anion moiety. The cation moiety contains an imidazolium cation. The anion moiety contains at least one anion selected from the group consisting of a dicyanamide anion, a thiocyanate anion, and a trifluoroacetate anion.

[0009] The inventors have conducted extensive research to solve the above-mentioned problems and have discovered that by using a specific ionic liquid compound as a curing agent in a composition containing an epoxy resin and an inorganic filler, it is possible to achieve both good low-temperature curing properties and a long life, and have completed the present disclosure.

[0010] Composition (X) can be made to have good low-temperature curing properties and an excellent life. The reason why composition (X) exhibits the above-mentioned effects due to its configuration is not necessarily clear, but can be speculated, for example, as follows. By containing epoxy resin (A), curing agent (B), and inorganic filler (C), composition (X) can increase the thermal conductivity of the cured product and improve heat dissipation. Furthermore, by using an ionic liquid compound (B1) as the curing agent (B) that reacts with epoxy resin (A) and forming a salt of an acid (anion) and a base (cation) in this ionic liquid compound (B1), the basicity of the imidazolium is suppressed, thereby suppressing reactivity at room temperature and improving life. In this case, when a dicyanamide anion, a thiocyanate anion, or a trifluoroacetate anion is used as the specific, moderately acidic anion, both low-temperature curing properties and an excellent life can be achieved.

[0011] As described above, according to the present disclosure, it is possible to provide a heat-dissipating resin composition that has good low-temperature curing properties and an excellent life.

[0012] 2. Details <Heat-dissipating resin composition> Composition (X) contains an epoxy resin (A), a curing agent (B), and an inorganic filler (C). Composition (X) preferably further contains a dispersant (D), and may further contain other components in addition to the above components as long as the effects of the present disclosure are not impaired. Each component will be described below.

[0013] [Epoxy Resin] The epoxy resin (A) is a component that serves as a matrix in the composition (X) to disperse the inorganic filler (C).

[0014] The epoxy resin (A) is not particularly limited as long as it is a compound having one or more epoxy groups in one molecule. The epoxy resin (A) preferably has two or more epoxy groups in one molecule.

[0015] Examples of the epoxy resin (A) include bisphenol-type epoxy resins, hydrogenated bisphenol-type epoxy resins, biphenyl-type epoxy resins, naphthalene ring-containing epoxy resins, alicyclic epoxy resins, dicyclopentadiene-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, triphenylmethane-type epoxy resins, aliphatic epoxy resins, triglycidyl isocyanurate, glycidyl group-containing silicone resins, and glycidylamine-type epoxy resins.

[0016] The epoxy resin (A) preferably contains a glycidylamine-type epoxy resin. The glycidylamine-type epoxy resin has a tertiary amino group, and the action of this amino group can improve the affinity of the epoxy resin (A) with the curing agent (B) and the inorganic filler (C). Commercially available glycidylamine-type epoxy resins include, for example, "EP3950S" from ADEKA Corporation.

[0017] The proportion of the epoxy resin (A) is preferably 5% by mass or more, more preferably 7% by mass or more, based on the total solid content of the composition (X). In this case, the viscosity of the composition (X) can be further reduced. The proportion of the epoxy resin (A) is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total solid content of the composition (X). In this case, the heat dissipation properties of the composition (X) can be further improved. The "total solid content" of the composition (X) refers to the sum of all components other than the solvent.

[0018] [Curing Agent] The curing agent (B) is a compound capable of undergoing a curing reaction with the epoxy resin (A).

[0019] The curing agent (B) in the composition (X) of this embodiment contains a specific ionic liquid compound (ionic liquid compound (B1)). The "ionic liquid compound" refers to an onium salt compound that is in a liquid state at around room temperature (25°C). The ionic liquid compound (B1) contains a cation moiety and an anion moiety.

[0020] (Cation Moiety) The cation moiety in the ionic liquid compound (B1) contains an imidazolium cation. "Imidazolium cation" refers to a cation having an imidazolium ring in which one of the two nitrogen atoms of imidazole (1,3-diazole) has become a nitrogen cation. The imidazolium cation is usually a monovalent cation. The hydrogen atom bonded to the nitrogen atom or carbon atom of the imidazolium ring may be substituted with a substituent such as an organic group. "Organic group" refers to a group containing at least one carbon atom.

[0021] Examples of imidazolium cations include cations represented by the following formula (1).

[0022]

[0023] In the formula (1), R １ ~R ５ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. １ ~R ５ Two or more of these may be combined with each other to form a ring structure having 3 to 20 ring members.

[0024] R １ ~R ５ Examples of the monovalent organic group represented by the formula (I) include a monovalent hydrocarbon group and a group formed by combining two or more monovalent hydrocarbon groups with one or more divalent groups selected from the group consisting of O, S, and NH.

[0025] Examples of the monovalent hydrocarbon group include a monovalent chain hydrocarbon group, a monovalent alicyclic hydrocarbon group, and a monovalent aromatic hydrocarbon group.

[0026] Examples of the monovalent chain hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl; alkenyl groups such as ethenyl; and alkynyl groups such as ethynyl. Examples of the monovalent alicyclic hydrocarbon group include cycloalkyl groups such as cyclopentyl and cyclohexyl; and cycloalkenyl groups such as cyclohexenyl. Examples of the monovalent aromatic hydrocarbon group include aryl groups such as phenyl, tolyl, diisopropylphenyl, and naphthyl; and aralkyl groups such as phenylmethyl.

[0027] R １ and R ３ is preferably a monovalent organic group having 1 to 20 carbon atoms, more preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 10 carbon atoms, and particularly preferably at least one of a methyl group and an ethyl group. ２ , R ４ and R ５ is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom, a methyl group or an ethyl group, and even more preferably a hydrogen atom.

[0028] The imidazolium cation is preferably a 1,3-dialkylimidazolium cation, and more preferably a 1-ethyl-3-methylimidazolium cation.

[0029] (Anion Moiety) The anion moiety in the ionic liquid compound (B1) contains at least one anion selected from the group consisting of a dicyanamide anion, a thiocyanate anion, and a trifluoroacetate anion. － The anion represented by —CN is referred to as a “thiocyanate anion.” － The anion represented by SCN is "trifluoroacetate anion" and the anion represented by CF ３ COO － The anion is represented by the formula:

[0030] These anions are all moderately acidic, that is, have a moderately high pKa, and are thought to be able to achieve both good low-temperature curing properties and an excellent life by forming a salt with the imidazolium cation.

[0031] The proportion of the ionic liquid compound (B1) relative to the curing agent (B) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass relative to the curing agent (B).

[0032] The molar ratio of the ionic liquid compound (B1) to the epoxy resin (A) (ionic liquid compound (B1) / epoxy resin (A)) is, for example, 0.6 or more and, for example, 1.4 or less.

[0033] The proportion of ionic liquid compound (B1) is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 0.2 mass% or more, and particularly preferably 0.4 mass% or more, based on the total solid content of composition (X). The proportion of ionic liquid compound (B1) is preferably 10 mass% or less, more preferably 3 mass% or less, even more preferably 1 mass% or less, and particularly preferably 0.7 mass% or less, based on the total solid content of composition (X).

[0034] The curing agent (B) may contain, in addition to the ionic liquid compound (B1), another curing agent (B2) other than the ionic liquid compound (B1).

[0035] Examples of the other curing agent (B2) include an ionic liquid compound other than the ionic liquid compound (B1), an imidazole curing agent, an acid anhydride curing agent, a phenol curing agent, an amine curing agent, a polymercaptan curing agent, a polyaminoamide curing agent, an isocyanate curing agent, and a blocked isocyanate curing agent.

[0036] Other ionic liquid compounds include, for example, compounds in which the cation moiety is an imidazolium cation, a pyridinium cation, a phosphonium cation, or the like, and the anion moiety is an acetate anion, a diethylphosphate anion, a bis(trifluoromethanesulfonyl)imide anion, a hexafluorophosphate anion, a hydrogen sulfate anion, a methyl sulfate anion, an ethyl sulfate anion, or the like.

[0037] Examples of the imidazole curing agent include 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, and 2-phenyl-4,5-dihydroxymethylimidazole.

[0038] Examples of the acid anhydride curing agent include methylbicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, and the like.

[0039] Examples of phenol curing agents include novolac resins such as phenol novolac resin, cresol novolac resin, and naphthol novolac resin; aralkyl resins such as phenol aralkyl resins having a phenylene skeleton or a biphenylene skeleton, and naphthol aralkyl resins having a phenylene skeleton or a biphenylene skeleton; polyfunctional phenol resins such as triphenolmethane resin; dicyclopentadiene phenol resins such as dicyclopentadiene phenol novolac resin and dicyclopentadiene naphthol novolac resin; terpene-modified phenol resins; bisphenol resins such as bisphenol A and bisphenol F; and triazine-modified novolac resins.

[0040] Examples of amine curing agents include ethyltoluenediamine, diethyltoluenediamine, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5-triethyl-2,6-diaminobenzene, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,5,3',5'-tetramethyl-4,4'-diaminodiphenylmethane, and dimethylthiotoluenediamine.

[0041] Preferably, the curing agent (B) does not contain another curing agent (B2), or the curing agent (B) contains another curing agent (B2), and the proportion of the other curing agent (B2) is less than 0.1 mass% relative to the total solid content of the composition (X). In this case, the life of the composition (X) can be further improved. Furthermore, the proportion of the other curing agent (B2) is more preferably 0.05 mass% or less, and even more preferably 0.01 mass% or less, relative to the total solid content of the composition (X). It is particularly preferred that the curing agent (B) does not contain another curing agent (B2).

[0042] Preferably, the curing agent (B) does not contain an imidazole curing agent as another curing agent (B2), or the curing agent (B) contains an imidazole curing agent, and the proportion of the imidazole curing agent is less than 0.1 mass% relative to the total solid content of the composition (X). In this case, the heat dissipation properties of the composition (X) can be further improved. Furthermore, the proportion of the imidazole curing agent is more preferably 0.05 mass% or less, and even more preferably 0.01 mass% or less, relative to the total solid content of the composition (X). It is particularly preferred that the curing agent (B) does not contain an imidazole curing agent.

[0043] The proportion of the curing agent (B) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and particularly preferably 0.4% by mass or more, based on the total solid content of the composition (X). The proportion of the curing agent (B) is preferably 10% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less, based on the total solid content of the composition (X). In this case, the composition (X) can further improve both its low-temperature curability and life.

[0044] The molar ratio of the curing agent (B) to the epoxy resin (A) (curing agent (B) / epoxy resin (A)) is, for example, 0.6 or more and, for example, 1.4 or less.

[0045] [Inorganic Filler] The inorganic filler (C) is a filler made of an inorganic material.

[0046] The thermal conductivity of the inorganic filler (C) is preferably 10 W / m K or more, more preferably 12 W / m K or more, and even more preferably 15 W / m K or more. In this case, the heat dissipation properties of the composition (X) can be further improved. The upper limit of the thermal conductivity of the inorganic filler (C) is not particularly limited, but is, for example, 50 W / m K or less, and preferably 30 W / m K or less.

[0047] The inorganic filler (C) preferably contains a filler made of at least one inorganic material selected from the group consisting of, for example, crystalline silica, aluminum oxide, aluminum nitride, aluminum, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, silver, copper, boron nitride, magnesium carbonate, anhydrous magnesium carbonate, graphite, carbon nanotubes, and graphene. In this case, the heat dissipation properties of the composition (X) can be further improved. Among these, it is preferable to contain a filler made of at least one inorganic material selected from the group consisting of aluminum nitride and aluminum oxide. The inorganic filler (C) may be surface-treated in advance with various surface treatment agents such as the coupling agents described below.

[0048] The volume average particle size of the inorganic filler (C) is, for example, preferably 0.1 μm or more and 50 μm or less, and more preferably 0.2 μm or more and 30 μm or less. The volume average particle size of the inorganic filler (C) can be measured as the particle size (D50) at which the cumulative total from the small diameter side reaches 50% in the volume-based particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer.

[0049] Two or more inorganic fillers (C) having different volume average particle diameters may be used, in which case one has a volume average particle diameter of, for example, 0.1 μm or more and 5 μm or less, and the other has a volume average particle diameter of, for example, 10 μm or more and 50 μm or less.

[0050] The total proportion of the inorganic filler (C) relative to the composition (X) is, for example, 30% by volume or more, preferably 40% by volume or more, and more preferably 50% by volume or more. The proportion of the inorganic filler (C) relative to the composition (X) is preferably 95% by volume or less, more preferably 90% by volume or less, and even more preferably 80% by volume or less. In these cases, the heat dissipation properties of the composition (X) can be further improved.

[0051] The proportion of the inorganic filler (C) is preferably 30% by mass or more, more preferably 45% by mass or more, based on the total solid content of the composition (X), and the proportion of the inorganic filler (C) is preferably 90% by mass or less, more preferably 85% by mass or less.

[0052] [Dispersant] The dispersant (D) is a component that can increase the dispersibility of the inorganic filler (C) (however, this excludes substances that fall under the category of the curing agent (B)). By including the dispersant (D), the content of the inorganic filler (C) in the composition (X) can be increased, and as a result, the heat dissipation properties of the composition (X) can be further improved.

[0053] Examples of the dispersant (D) include various surfactants. Examples of the surfactant include nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants. Among these, nonionic surfactants are preferred.

[0054] The content of the dispersant (D) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, based on the total solid content of the composition (X). The content of the dispersant (D) is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

[0055] [Other Components] Examples of other components include solvents, coupling agents, release agents, flame retardants, flame retardant assistants, ion trapping agents, pigments, colorants, stress reducing agents, tackifiers, and silicone flexibilizers.

[0056] The composition (X) generally does not contain a solvent as another component. Since the composition (X) does not contain a solvent, a drying step after application is not required.

[0057] The coupling agent can improve the affinity of the inorganic filler (E) with the epoxy compound (A) and the curing agent (B). Examples of the coupling agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, and aluminum / zirconium coupling agents. Examples of the silane coupling agent include glycidoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; aminosilanes such as N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; alkylsilanes; ureidosilanes; and vinylsilanes.

[0058] Examples of the release agent include carnauba wax, stearic acid, montanic acid, carboxyl group-containing polyolefin, ester wax, polyethylene oxide, and metal soap.

[0059] Examples of the flame retardant include magnesium hydroxide, aluminum hydroxide, and red phosphorus.

[0060] Examples of colorants include carbon black, red iron oxide, titanium oxide, phthalocyanine, and perylene black.

[0061] Examples of the stress reducing agent include silicone elastomer, silicone resin, silicone oil, butadiene rubber, etc. Examples of the butadiene rubber include methyl acrylate-butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, etc.

[0062] When composition (X) contains other components, the proportion of the other components is, for example, 0.01 mass % or more and, for example, 1 mass % or less, based on the total solid content of composition (X).

[0063] Composition (X) can be suitably used, for example, to form a heat-dissipating sheet, etc., and is particularly suitable for forming a sheet for covering electric / electronic components, etc. Composition (X) can also be suitably used as a heat-dissipating adhesive, etc. Composition (X) has good low-temperature curing properties, and is therefore suitable for applications in which it is heat-cured at 150°C or less.

[0064] <Method for producing heat-dissipating resin composition> Composition (X) can be prepared, for example, by mixing the components of composition (X). More specifically, raw materials including, for example, epoxy resin (A), curing agent (B), carbon material (C), and compound (D) are mixed until sufficiently uniform using a mixer, blender, or the like, and then melt-mixed while heated using a kneader such as a heat roll or kneader, and then cooled to room temperature. The mixture thus obtained can be pulverized by known means to produce powdered composition (X). Composition (X) does not have to be in powder form and may be, for example, in tablet form. When composition (X) is in tablet form, it is preferable that the dimensions and mass of composition (X) are suitable for the molding conditions.

[0065] <Characteristics> The composition (X) cures, for example, at a temperature of 150° C. or less. The composition (X) preferably cures at a temperature of 120° C. or more and 140° C. or less. The curing time of the composition (X) is, for example, 1 minute or more and 10 hours or less, and preferably 1 hour or more and 5 hours or less.

[0066] Composition (X) is usually in a paste form at room temperature (25°C). "In a paste form" means that the viscosity measured using an E-type viscometer under measurement conditions of 0.3 rpm and 200 s is, for example, 100 Pa s or more and 3000 Pa s or less. Since composition (X) is in a paste form at room temperature, it has excellent coatability and can be suitably used for forming heat dissipation sheets, etc.

[0067] The viscosity of composition (X) at 25°C is, for example, 100 Pa s or more, preferably 200 Pa s or more, and more preferably 300 Pa s or more. The viscosity of composition (X) at 25°C is, for example, 1000 Pa s or less, preferably 800 Pa s or less, and more preferably 700 Pa s or less.

[0068] The heat dissipation property of the composition (X) can be evaluated by the thermal conductivity (W / m·K) of the composition (X) before curing, the thermal resistance (K / W) before or after curing, and the like.

[0069] (Summary) As is apparent from the above-described embodiments, the present disclosure includes the following aspects.

[0070] A heat-dissipating resin composition according to a first aspect of the present disclosure contains an epoxy resin (A), a curing agent (B), and an inorganic filler (C). The curing agent (B) contains an ionic liquid compound. The ionic liquid compound contains a cation moiety and an anion moiety. The cation moiety contains an imidazolium cation, and the anion moiety contains at least one anion selected from the group consisting of a dicyanamide anion, a thiocyanate anion, and a trifluoroacetate anion.

[0071] According to the first aspect, the composition (X) has good low-temperature curing properties and also has an excellent life.

[0072] In the heat-dissipating resin composition according to the second aspect, in the first aspect, the inorganic filler (C) has a thermal conductivity of 10 W / m·K or more.

[0073] According to the second aspect, the heat dissipation properties of the heat dissipation resin composition can be further improved.

[0074] In the heat-dissipating resin composition according to the third aspect, in the first or second aspect, the inorganic filler (C) comprises a filler made of at least one inorganic material selected from the group consisting of crystalline silica, aluminum oxide, aluminum nitride, aluminum, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, silver, copper, boron nitride, magnesium carbonate, anhydrous magnesium carbonate, graphite, carbon nanotubes, and graphene.

[0075] According to the third aspect, the heat dissipation properties of the heat dissipation resin composition can be further improved.

[0076] In the heat-dissipating resin composition according to the fourth aspect, in any one of the first to third aspects, the proportion of the inorganic filler (C) relative to the heat-dissipating resin composition is 40% by volume or more and 95% by volume or less.

[0077] According to the fourth aspect, the heat dissipation properties of the heat dissipation resin composition can be further improved.

[0078] The heat-dissipating resin composition according to a fifth aspect is the heat-dissipating resin composition according to any one of the first to fourth aspects, further comprising a dispersant (D).

[0079] According to the fifth aspect, the content of the inorganic filler (C) in the heat-dissipating resin composition can be further increased, and as a result, the heat-dissipating properties of the heat-dissipating resin composition can be further improved.

[0080] In the heat-dissipating resin composition according to the sixth aspect, in any one of the first to fifth aspects, the curing agent (B) does not contain an imidazole curing agent, or the curing agent (B) contains an imidazole curing agent, and the proportion of the imidazole curing agent is less than 0.1 mass% with respect to the total solid content of the heat-dissipating resin composition.

[0081] According to the sixth aspect, the life of the heat-dissipating resin composition can be further improved.

[0082] In the heat-dissipating resin composition according to the seventh aspect, in any one of the first to sixth aspects, the composition is cured at 150° C. or less.

[0083] According to the seventh aspect, the heat-dissipating resin composition has good low-temperature curing properties, and therefore can be suitably used in applications requiring heat curing at 150°C or less.

[0084] The heat-dissipating resin composition according to an eighth aspect is the heat-dissipating resin composition according to any one of the first to seventh aspects, which is in a paste form at room temperature.

[0085] According to the eighth aspect, the heat-dissipating resin composition is in a paste state at room temperature, and therefore can be suitably used to form a heat-dissipating sheet or the like.

[0086] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to only these examples.

[0087] 1. Preparation of Heat-Dissipating Resin Compositions [Examples 1 to 3, Comparative Examples 1 to 16, and Reference Examples 1 to 4] The raw materials were blended in the amounts (mass%) shown in Table 1 below, and mixed and dispersed using a planetary centrifugal mixer "Awatori Rentaro ARV-310" manufactured by Thinky Corporation at 1000 rpm for 1 minute to obtain paste-like heat-dissipating resin compositions. The "volume %" for component (C) in Table 1 indicates the total volume ratio of the inorganic filler (C) to 100 volume% of the heat-dissipating resin composition. Details of the raw materials are as follows: (Component (A)) Epoxy compound 1: aromatic glycidylamine type epoxy resin (ADEKA RESIN EP-3050S, viscosity: 650 mPa·s (25°C), epoxy equivalent: 95 g / eq) (Component (B)) Ionic liquid compound a1: 1-ethyl-3-methylimidazolium trifluoroacetate Ionic liquid compound a2: 1-ethyl-3-methylimidazolium dicyanamide Ionic liquid compound a3: 1-ethyl-3-methylimidazolium thiocyanate (Component (B')) Ionic liquid compound b1: 1-ethyl-3-methylimidazolium acetate Ionic liquid compound b2: 1-ethyl-3-methylimidazolium diethylphosphate Ionic liquid compound b3: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide - Ionic liquid compound b4: 1-ethyl-3-methylimidazolium hexafluorophosphate - Ionic liquid compound b5: 1-ethyl-3-methylimidazolium hydrogensulfate - Ionic liquid compound b6: 1-ethyl-3-methylimidazolium methylsulfate - Ionic liquid compound b7: 1-ethyl-3-methylimidazolium ethylsulfate (Ionic liquid compounds a1 to a3 of component (B) and ionic liquid compounds b1 to b7 of component (B') are reagents manufactured by Tokyo Chemical Industry Co., Ltd.) - Imidazole compound 1: 2-ethyl-4-methylimidazole ("Curezol 2E4MZ" manufactured by Shikoku Chemical Industries, Ltd.) - Imidazole compound 2: 2-heptadecylimidazole ("Curezol C17Z" manufactured by Shikoku Chemical Industries, Ltd.) - Imidazole compound 3: 2-phenyl-4,5-dihydroxymethylimidazole ("Curezol 2PHZ-PW" manufactured by Shikoku Chemical Industries, Ltd.) - Imidazole compound 4: Mixture of 2-ethyl-4-methylimidazole and trimethyl phosphate (mass ratio: 2-ethyl-4-methylimidazole:trimethyl phosphate = 5:1) - Imidazole compound 5: Mixture of 2-ethyl-4-methylimidazole and tributyl borate (mass ratio: 2-ethyl-4-methylimidazole:tributyl borate = 5:1) (Trimethyl phosphate in imidazole compound 4 and tributyl borate in imidazole compound 5 were added to improve the service life.) Imidazole compound 6: 2-methylimidazole ("2MZ-H" manufactured by Shikoku Chemical Industries, Ltd.) (Component (C)) Inorganic filler 1: aluminum nitride ("AN-HF30LGL-HTZ" manufactured by Combustion Synthesis Co., Ltd., D50: 30 μm, thermal conductivity: 170 W / m·K) Inorganic filler 2: alumina ("Advanced Alumina AA-2" manufactured by Sumitomo Chemical Co., Ltd., D50: 2 μm, thermal conductivity: 35 W / m·K) Inorganic filler 3: alumina ("Advanced Alumina AA-03" manufactured by Sumitomo Chemical Co., Ltd., D50: 0.4 μm, thermal conductivity: 35 W / m·K) (Component (D)) Dispersant 1: Dispersant for inorganic fillers (BYK-W9010 manufactured by BYK-Chemie).

[0088] 2. Evaluation [Viscosity] The viscosity of the prepared heat-dissipating resin composition was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., model number RC-215) under conditions of 25°C, a rotation speed of 0.3 rpm, and 200 s. The viscosity of the heat-dissipating resin composition can be evaluated according to the following criteria. A (good): 3000 Pa s or less. B (poor): More than 3000 Pa s.

[0089] [Low-temperature curing property] The heat-dissipating resin composition prepared above was evaluated for low-temperature curing property. The low-temperature curing property was evaluated by adding a predetermined amount of the heat-dissipating resin composition to a metal container such as an aluminum cup, heating at 150°C for 3 hours, and then determining whether the composition was liquid or solidified. The low-temperature curing property of the heat-dissipating resin composition was evaluated according to the following criteria. A (Good): A uniform cured product was obtained without any unevenness. B (Slightly poor): The composition cured, but an uneven and non-uniform cured product was obtained. C (Poor): The composition was not cured.

[0090] [Life] The life of the prepared heat-dissipating resin composition was evaluated by the following method. The life was evaluated by measuring the viscosity of the heat-dissipating resin composition paste immediately after preparation, storing it in a thermostatic chamber at 25°C, and taking it out every day to measure the viscosity each time. The life of the heat-dissipating resin composition was evaluated according to the following criteria. A (Good): The viscosity after 2 days was 3000 Pa s or less. B (Poor): The viscosity after 2 days was more than 3000 Pa s.

[0091] [Heat dissipation property] The heat dissipation property of the prepared heat dissipation resin composition was measured by measuring the thermal conductivity (W / m K) of the uncured heat dissipation resin composition and the thermal resistance (K / W) (thickness 100 μm) of the heat dissipation resin composition before and after curing. The measurement of heat dissipation property was performed according to the following procedure.

[0092] (Thermal Conductivity) The measurement sample was set on the probe of a DynTIM Tester manufactured by Mentor Graphics in accordance with ASTM D5470. Specifically, a sample of uncured heat-dissipating resin composition was sandwiched between two aluminum plates, and pressure was applied with the DynTIM Tester so that the sample thickness was 100 μm. After that, the pressure was set to 0 at a predetermined thickness and the thermal resistance (K / W) was measured, and the thermal conductivity (W / m K) was calculated from the measured values ​​of thermal resistance at several thicknesses. In addition, thermal grease ("G-779" manufactured by Shin-Etsu Chemical Co., Ltd.) was used between the aluminum plate and the DynTIM Tester probe to reduce interfacial thermal resistance. The temperature gradient at this time was 60 ° C. in the heating section and 25 ° C. in the cooling section.

[0093] (Thermal Resistance) An uncured measurement sample was sandwiched between two aluminum plates and heated at 150°C for 3 hours to cure. The thermal resistance of the resulting cured product was measured while applying grease between the aluminum plate probes and applying pressure, and the thermal resistance (K / W) after curing was determined. The thermal resistance before curing was determined by measuring the thermal resistance of the uncured measurement sample.

[0094] In Table 1, (*1) indicates that viscosity measurement was not performed for the corresponding comparative example. (*2) indicates that life evaluation was not performed for the corresponding comparative example. (*3) indicates that heat dissipation properties (thermal conductivity, thermal resistance (before curing), thermal resistance (after curing)) were not measured for the corresponding comparative example and reference example.

[0095]

[0096] As is clear from the results in Table 1, the heat-dissipating resin compositions of Examples 1 to 3 have good low-temperature curing properties and also have excellent life. The heat-dissipating resin compositions of Comparative Examples 1 to 16 were insufficient in at least one of low-temperature curing properties and life, and were unable to achieve both. Reference Examples 1 to 4 were obtained by adding an imidazole curing agent to the heat-dissipating resin composition of Example 2, and had insufficient life.

Claims

1. A heat dissipating resin composition comprising: an epoxy resin (A); a curing agent (B); and an inorganic filler (C); the curing agent (B) contains an ionic liquid compound; the ionic liquid compound contains a cation moiety and an anion moiety; the cation moiety contains an imidazolium cation; and the anion moiety contains at least one anion selected from the group consisting of a dicyanamide anion, a thiocyanate anion, and a trifluoroacetate anion.

2. The heat dissipating resin composition according to claim 1, wherein the inorganic filler (C) has a thermal conductivity of 10 W / m·K or more.

3. The heat dissipating resin composition according to claim 1 or 2, wherein the inorganic filler (C) comprises a filler made of at least one inorganic material selected from the group consisting of crystalline silica, aluminum oxide, aluminum nitride, aluminum, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, silver, copper, boron nitride, magnesium carbonate, anhydrous magnesium carbonate, graphite, carbon nanotubes and graphene.

4. The heat dissipating resin composition according to claim 1 or 2, wherein the proportion of the inorganic filler (C) is 40 volume % or more and 95 volume % or less relative to the heat dissipating resin composition.

5. The heat dissipating resin composition according to claim 1 or 2, further comprising a dispersant (D).

6. The heat dissipating resin composition according to claim 1 or 2, wherein the curing agent (B) does not contain an imidazole curing agent, or the curing agent (B) contains an imidazole curing agent, and the proportion of the imidazole curing agent is less than 0.1 mass% based on the total solid content of the heat dissipating resin composition.

7. The heat dissipating resin composition according to claim 1 or 2, which is cured at 150°C or less.

8. The heat dissipating resin composition according to claim 1 or 2, which is in a paste form at room temperature.

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