Thermally conductive silicone composition, sheet using the same, and method for manufacturing the same

Abstract

The composition of the present application contains A-C below, A: linear two-terminal reactive polydimethylsiloxane. B: thermally conductive filler containing B1 and B2 and B3 below, 800-2500 parts by mass with respect to 100 parts by mass of the above A component. B1: thermally conductive filler with an average particle size of 0.1-1.0 μm, and surface treated with a surface treatment agent having a reactive group free of unsaturated bond. B2: thermally conductive filler with an average particle size of 1.0-10 μm, and surface treated with a surface treatment agent having a reactive group containing unsaturated bond. B3: thermally conductive filler with an average particle size of 10-100 μm, and surface treated with a surface treatment agent having the above reactive group free of unsaturated bond or the above reactive group containing unsaturated bond. C: curing catalyst: catalytic amount. Thus, a high-strength thermally conductive silicone composition and a sheet using the same are provided.

Description

TECHNICAL FIELD

[0001] The present application relates to a thermally conductive silicone composition suitable for being interposed between a heat generating portion of an electrical and electronic component or the like and a heat sink, a thermally conductive silicone sheet, and a manufacturing method thereof. BACKGROUND

[0002] The performance of a semiconductor such as a CPU has been remarkably improved in recent years, and along with this, the amount of heat generated has also become large. In an electronic component such as a semiconductor, a heat sink is installed, and a thermally conductive silicone sheet is used in order to improve the adhesion between the semiconductor and the heat sink. In the past, an addition reaction-curable kneaded heat sink or sheet has been used in transistors and capacitors of power supplies and the like. In recent years, with the increase in the amount of heat generated, such heat sink materials have also been required to be highly thermally conductive. In Patent Documents 1 to 3, a thermally conductive silicone sheet using a reinforcing material such as a glass fiber cloth has been proposed in order to make the handleability good.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Re-publication No. 2018-061447

[0006] Patent Document 2: Japanese Re-publication No. 2018-020862

[0007] Patent Document 3: Japanese Patent Application Publication No. 2017-222884 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, the thermal resistance of the conventional thermally conductive silicone sheet using a reinforcing material such as a glass fiber cloth is large, and there is a large problem in the development of a highly thermally conductive product.

[0010] The present application provides a sheet using a highly thermally conductive silicone composition that can be handled sufficiently even without a reinforcing material such as a glass fiber cloth and a manufacturing method thereof.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] The thermally conductive silicone composition of the present application contains A to C described below.

[0013] A linear two-terminal reactive polydimethylsiloxane

[0014] B a thermally conductive filler containing B-1, B-2, and B-3 described below, 800 to 2500 parts by mass with respect to 100 parts by mass of the A component

[0015] B-1 thermally conductive filler having an average particle diameter of 0.1 μm or more and less than 1.0 μm, and surface-treated with a surface treatment agent having a reactive group not containing an unsaturated bond

[0016] B-2 thermally conductive filler having an average particle diameter of 1.0 μm or more and less than 10 μm, and surface-treated with a surface treatment agent having a reactive group containing an unsaturated bond

[0017] B-3 thermally conductive filler having an average particle diameter of 10 μm or more and 100 μm or less, and surface-treated with at least one selected from the surface treatment agent having the above-described reactive group not containing an unsaturated bond or the above-described reactive group containing an unsaturated bond

[0018] C curing catalyst: a catalytic amount

[0019] The thermally conductive silicone sheet of the present application is obtained by sheet molding and heat curing the above-described thermally conductive silicone composition, and has a tensile strength of 5 MPa or more.

[0020] The manufacturing method of the thermally conductive silicone sheet of the present application uniformly mixes the composition containing the above-described A to C, performs sheet molding, and heat cures.

[0021] Effects of the Invention

[0022] The thermally conductive silicone composition of the present application, by being set to a composition containing the above-described A to C, can be a high strength that can be sufficiently handled even without a reinforcing material sheet such as a glass fiber cloth. The thermally conductive silicone sheet of the present application, by sheet molding and heat curing the above-described thermally conductive silicone composition, can have a tensile strength of 5 MPa or more and a thermal conductivity of 1 W / m·K or more. The manufacturing method of the present application can efficiently and reasonably manufacture the above-described thermally conductive silicone sheet at a low cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1A - B is an explanatory diagram showing a method for measuring the thermal conductivity of a sample in one embodiment of the present application.

[0024] Figure 2 is a schematic explanatory diagram of a spherical thermally conductive filler. DETAILED DESCRIPTION

[0025] The thermally conductive silicone composition of the present application contains the following A to C.

[0026] A linear two-terminal reactive polydimethylsiloxane: 100 parts by mass

[0027] B thermally conductive filler containing the following B-1, B-2, and B-3: 800 to 2500 parts by mass

[0028] B-1 thermally conductive filler having an average particle size of 0.1 μm or more and less than 1.0 μm, and surface-treated with a surface-treatment agent having a reactive group not containing an unsaturated bond

[0029] B-2 thermally conductive filler having an average particle size of 1.0 μm or more and less than 10 μm, and surface-treated with a surface-treatment agent having a reactive group containing an unsaturated bond

[0030] B-3 thermally conductive filler having an average particle size of 10 μm or more and 100 μm or less, and surface-treated with at least one selected from the group consisting of a surface-treatment agent having the above-mentioned reactive group not containing an unsaturated bond or the above-mentioned reactive group containing an unsaturated bond

[0031] C curing catalyst: a catalytic amount

[0032] The above-mentioned A component is preferably a linear organopolysiloxane having one reactive group at each of both molecular chain terminals, having an alkyl group, a phenyl group, or the like organic group at a side chain, or a combination thereof. Note that the linear organopolysiloxane can also be a compound having a small amount of branched structure (trifunctional siloxane unit) in the molecule. As one example, a compound having dimethylvinylsiloxy groups at both molecular chain terminals and a dimethylpolysiloxane main chain can be given. The above-mentioned A component is a linear organopolysiloxane that becomes linear after curing because it has one vinyl group at each of both molecular chain terminals, and thus can exhibit softness.

[0033] As specific examples of the above-mentioned A component, for example, a dimethylpolysiloxane having dimethylvinylsiloxy groups at both molecular chain terminals, a dimethylpolysiloxane having methylphenylvinylsiloxy groups at both molecular chain terminals, a dimethylsiloxane-methylphenylsiloxane copolymer having dimethylvinylsiloxy groups at both molecular chain terminals, a dimethylsiloxane-methylvinylsiloxane copolymer having dimethylvinylsiloxy groups at both molecular chain terminals, a dimethylsiloxane-methylvinylsiloxane copolymer having trimethylsiloxy groups at both molecular chain terminals, a methyl(3,3,3-trifluoropropyl)polysiloxane having dimethylvinylsiloxy groups at both molecular chain terminals, a dimethylsiloxane-methylvinylsiloxane copolymer having silanol groups at both molecular chain terminals, and a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having silanol groups at both molecular chain terminals, and the like can be given. These can be used alone or in combination of two or more. Among these, a linear two-terminal reactive dimethylsiloxane represented by the following general formula (1) is preferred.

[0034] X[Si(CH3)2-O-] n Si(CH3)2-Y (1)

[0035] (wherein the polymerization degree n is in the range of 5 to 2100, and the terminal groups X and Y are vinyl groups)

[0036] The thermally conductive filler used in the present application is preferably an inorganic powder such as alumina (aluminum oxide), zinc oxide, silicon oxide, silicon carbide, aluminum nitride, boron nitride, etc. Alumina is preferred because it is inexpensive. Furthermore, the shape of the thermally conductive filler is not particularly limited and can be spherical, irregular, acicular, platy, etc. Spherical is preferred. The thermally conductive filler can be used alone or in combination with two or more kinds. The thermally conductive filler is compounded at 800 to 2500 parts by mass relative to 100 parts by mass of the A component. By this means, the thermal conductivity can be improved.

[0037] The thermally conductive filler used in the present application has an average particle diameter and is subjected to a specific surface treatment.

[0038] (1) B-1: a thermally conductive filler having an average particle diameter of 0.1 μm or more and less than 1.0 μm and subjected to a surface treatment with a surface treatment agent having a reactive group that does not contain an unsaturated bond

[0039] (2) B-2: a thermally conductive filler having an average particle diameter of 1.0 μm or more and less than 10 μm and subjected to a surface treatment with a surface treatment agent having a reactive group that contains an unsaturated bond

[0040] (3) B-3: a thermally conductive filler having an average particle diameter of 10 μm or more and 100 μm or less and subjected to a surface treatment with at least one selected from the surface treatment agent having the above-mentioned reactive group that does not contain an unsaturated bond or the above-mentioned reactive group that contains an unsaturated bond

[0041] The use of at least three kinds of average particle diameters that are different from each other is intended to be most densely packed. If most densely packed, the thermal conductivity can be improved. The average particle diameter is the D50 (median particle diameter) of the cumulative particle size distribution based on the volume basis in the particle size distribution measurement using the laser diffraction light scattering method. As a measurement device, for example, there is the laser diffraction / scattering type particle distribution measuring device LA-950S2 manufactured by Horiba, Ltd.

[0042] The mixing ratio of B-1, B-2, and B-3 of the above-mentioned thermally conductive filler is (the total of the surface area of B-3 + the total of the surface area of B-2) = K x (the total of the cross-sectional area of B-1), and it is preferably set to a range of K = 1 to 5.

[0043] In order to most densely pack the filler in the base material, it is necessary to combine the three kinds of fillers having different particle diameters of B-1, B-2, and B-3 in balance, and if the numerical value of K obtained from the above-mentioned calculation formula is in the range of 1 to 5, the particle diameter and the packing amount of the filler become a combination in which the gap between the fillers becomes the smallest, thus becoming a state close to the most dense packing, and a high thermal conductivity can be obtained.

[0044] When the above-mentioned A component is set to 100 parts by mass, with respect to the mixing ratio of B-1 to B-2 to B-3, B-1 is preferably 150 to 450 parts by mass, B-2 is preferably 250 to 550 parts by mass, and B-3 is preferably 400 to 1500 parts by mass.

[0045] The filler of B-1 is a small particle diameter filler, and is surface-treated with a surface treatment agent having a reactive group free of an unsaturated bond. The above-mentioned surface treatment agent is, for example, preferably an alkoxy silane compound represented by the following general formula (2).

[0046] R 2 b R 3 c Si(OR 4 ) 4-b-c (2)

[0047] (In the formula, R 2 is independently an alkyl group having 6 to 15 carbon atoms, R 3 is independently an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms, R 4 is independently an alkyl group having 1 to 6 carbon atoms, b is an integer of 1 to 3, and c is an integer of 0 to 2, where b + c is an integer of 1 to 3.)

[0048] In the above-mentioned formula (2), as the alkyl group represented by R 2 , for example, hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, and the like can be given. If the number of carbon atoms of the alkyl group represented by R 2 is in the range of 6 to 15, the wettability of the thermally conductive filler is sufficiently improved, the handleability is good, and the low temperature characteristics of the thermally conductive silicone composition become good. As the alkyl group represented by R 3The represented non-substituted or substituted monovalent hydrocarbon group, for example, can be exemplified by alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl and the like; cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl and the like; aryl groups such as phenyl, tolyl, xylyl, naphthyl, biphenyl and the like; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, methylbenzyl and the like; and groups obtained by substituting a part or all of the hydrogen atoms bonded to the carbon atoms in these groups with halogen atoms such as fluorine, chlorine, bromine and the like, a cyano group and the like, such as chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl and the like. Representative monovalent hydrocarbon groups are monovalent hydrocarbon groups having 1 to 10 carbon atoms, and particularly representative monovalent hydrocarbon groups are monovalent hydrocarbon groups having 1 to 6 carbon atoms. Preferable monovalent hydrocarbon groups can be exemplified by non-substituted or substituted alkyl groups having 1 to 3 carbon atoms such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, cyanoethyl and the like; and non-substituted or substituted phenyl groups such as phenyl, chlorophenyl, fluorophenyl and the like. As R 4 The represented alkyl group, for example, can be exemplified by methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl and the like, among which, methyl and ethyl are preferable. The above-mentioned alkoxysilane compound is also referred to as a silane coupling agent. The silane coupling agent can be used alone as one kind, or two or more kinds can be used in combination.

[0049] The filler of B-2 is a medium particle diameter filler, and is surface-treated with a surface treatment agent having a reactive group containing an unsaturated bond. The above-mentioned surface treatment agent is preferably an alkoxysilane compound, similarly to B-1.

[0050] R 5 b R 3 c Si(OR 4 ) 4-b-c (3)

[0051] In the above-mentioned formula (3), R 5 is a reactive group containing an unsaturated bond, and can be exemplified by alkenyl, acryloyl, methacryloyl, vinyl, styryl and the like.

[0052] The above-mentioned surface treatment agent contains the above-mentioned unsaturated bond (carbon-carbon double bond), and therefore, when the heat conductive silicone composition is heat-cured, the unsaturated bond (carbon-carbon double bond) is cleaved, and the strength of the heat conductive silicone sheet is improved by cross-linking reaction with the A component.

[0053] If the reaction is also applied to B-1 having a small particle diameter, the strength is further improved, but the moldability of the heat conductive silicone composition before heat curing becomes very high, and processing becomes difficult, and thus is not preferable. Therefore, it is preferable to separately use the reaction group having an unsaturated bond with or without a surface treatment agent depending on the particle diameter of the filler.

[0054] The filler of B-3 is a large particle diameter filler, and is surface treated with at least one selected from the surface treatment agent having the above reaction group not containing an unsaturated bond or the above reaction group containing an unsaturated bond.

[0055] The above heat conductive silicone composition preferably has a moldability of 1 to 50 before curing. The moldability is obtained as a value obtained by dividing the thickness (t) after compression of a test sample between two metal plates at a certain load (100 N) for a certain time (15 seconds) at a measurement temperature of 25°C by the thickness (t0) before compression, using a Wallace plastometer according to JIS K 6300-3, ISO 2007: 1991. The smaller the P0, the softer it is.

[0056] The above curing catalyst is preferably an organic peroxide. The organic peroxide is a catalyst for curing by a radical reaction. As the organic peroxide, for example, benzoyl peroxide, di(p-methylbenzoyl) peroxide, di(o-methylbenzoyl) peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy) hexane, di-tert-butyl peroxide, tert-butylperoxybenzoate can be exemplified. The content of the organic peroxide is an amount necessary for curing of the present composition, and specifically, 0.5 to 30 parts by mass, and particularly preferably 1 to 20 parts by mass, relative to 100 parts by mass of the A component. If the content of the present component is less than the lower limit of the above range, the curing becomes insufficient, and thus sufficient sheet strength cannot be obtained, and in addition, oil bleeding is sometimes promoted, and if it exceeds the upper limit of the above range, the sheet is sometimes embrittled, or foaming occurs.

[0057] The above heat conductive silicone composition is sheet-formed and heat-cured to become a heat conductive silicone sheet having a tensile strength of 5 MPa or more and a thermal conductivity of 1 W / m-K or more. The tensile strength is preferably 5 to 12 MPa, and more preferably 6 to 10 MPa. The thermal conductivity is preferably 1 to 8 W / m-K, and more preferably 2 to 5 W / m-K.

[0058] A reinforcing material sheet such as a glass fiber cloth can also be interposed in the above heat conductive silicone sheet, but it is preferable not to contain it in order to improve the heat conductivity. Even without the reinforcing material sheet such as a glass fiber cloth, a heat conductive silicone sheet that has a strength that can be sufficiently handled, softness, heat conductivity, mass productivity, and a low price can be produced.

[0059] The production method of the present application is to uniformly mix a composition containing the above-mentioned A-C components, perform sheet molding, and heat cure to obtain a heat-conducting silicone sheet. The sheet molding is preferably performed by a method of calendering while sandwiching in a polyester film. The thickness of the sheet is preferably 0.05 to 2 mm. The heat curing is preferably performed by heat treatment at a temperature of 120 to 180°C for 5 to 30 minutes.

[0060] In the composition of the present application, components other than the above-mentioned components can be incorporated as needed. For example, a heat resistance improving agent such as red iron oxide, titanium oxide, cerium oxide, a flame retardant aid, a cure retardant, and the like can be added. As the cure retardant, acetylenylcyclohexanol and the like are available. An organic pigment or an inorganic particle pigment can also be added for the purpose of coloring or toning.

[0061] Examples

[0062] The following is explained using examples. The present application is not limited to the examples. Various parameters are measured by the following methods.

[0063] <Plasticity>

[0064] The plasticity is measured according to JIS K 6300-3, ISO 2007:1991, using a Wallace plastometer, and is obtained as a value obtained by dividing the thickness (t) of a sample after compression between two metal plates at a certain load (100 N) for a certain time (15 seconds) at a measurement temperature of 25°C by the thickness (t0) before compression, as plasticity (P0 = t / t0 x 100). The smaller P0 is, the softer it indicates.

[0065] <Tensile Strength>

[0066] As for the tensile strength, a cured sheet of a composition of an example or a comparative example is cut into a dumbbell-shaped test piece of No. 3 shape prescribed in JIS K 6251, and a tensile test is performed using an Autograph AGS-X manufactured by Shimadzu Corporation to measure the tensile strength at the time of breakage of the cured sheet.

[0067] <Thermal Conductivity>

[0068] The thermal conductivity is measured by a Hot Disk (in accordance with ISO / CD 22007-2). The thermal conductivity measuring device 1 as shown in Figure 1A holds a polyimide film sensor 2 with two test pieces 3a, 3b, applies a constant power to the sensor 2 to make it constantly heat, and analyzes the thermal characteristics from the temperature rise of the sensor 2. The diameter of the front end 4 of the sensor 2 is 7 mm, and as shown in Figure 1B , becomes a double helix structure of electrodes, and is provided with an electrode 5 for applying current and an electrode (temperature measuring electrode) 6 for resistance value at the lower part. The thermal conductivity is calculated by the following formula (Mathematical Formula 1).

[0069] [Math. 1]

[0070]

[0071] λ: thermal conductivity (W / m-K)

[0072] P0: constant power (W)

[0073] r: radius of sensor (m)

[0074] τ:

[0075] α: thermal diffusivity of sample (m 2 / s)

[0076] t: measurement time (s)

[0077] D(τ): function of dimensionless τ

[0078] ΔT(τ): temperature rise of sensor (K)

[0079] <Method for calculating K value of thermally conductive filler>

[0080] Figure 2 A schematic explanatory view of a spherical thermally conductive filler is shown in FIG. 1. In FIG. 1, D1 is the particle diameter, and cs1 is the cross-sectional area of the particle. The thermally conductive filler of the present application can be expressed as "(sum of surface areas of B-3 + sum of surface areas of B-2) = K x (sum of cross-sectional areas of B-1)", and can be expanded as follows. Figure 2 K = (sum of surface areas of B-3 + sum of surface areas of B-2) / (sum of cross-sectional areas of B-1)

[0081] K = (∑sa2+∑sa3) / ∑cs1

[0082] ∑cs1 = cs1 x q1

[0083] ※cs1 = (D1 / 2)2 x π, q1 = M1 / (4 / 3 x π x (D1 / 2)3 x d1)

[0084] ∑sa2 = sa2 x M2

[0085] ∑sa3 = sa3 x M3

[0086] wherein ∑cs1: sum of cross-sectional areas of B-1 (m 2 )

[0087] cs1: cross-sectional area of B-1 (m 2 )

[0088] D1: particle diameter (m)

[0089] q1: average number of particles (pieces) of B-1

[0090] D1: average particle diameter (m) of B-1

[0091] M1: weight parts (phr) of B-1

[0092] d1: density (g / m 3 )

[0093] ∑sa2: total surface area (m 2 )

[0094] sa2: surface area (m 2 / g) of B-2

[0095] M2: weight parts (phr) of B-2

[0096] ∑sa3: total surface area (m 2 )

[0097] sa3: surface area (m 2 / g) of B-3

[0098] M3: weight parts (phr) of B-3

[0099] The calculated values of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1.

[0100] Table 1

[0101]

[0102] The calculated values of Examples 7 to 8 and Comparative Example 4 are shown in Table 2.

[0103] Table 2

[0104]

[0105] (Examples 1 to 8 and Comparative Examples 1 to 4)

[0106] 1 Raw material components

[0107] (1) A component (base resin)

[0108] A-1: linear two-terminal vinyl polydimethylsiloxane, molecular weight 140,000, polymerization degree 1891

[0109] A-2: linear two-terminal vinyl polydimethylsiloxane, molecular weight 72,000, polymerization degree 972

[0110] (2) B component (thermally conductive filler)

[0111] B-1-1: spherical alumina, average particle diameter 0.27 μm, specific surface area 6.7 m2 / g, density 3.9 x 10 2 6 g / m 3

[0112] B-1-2: spherical alumina, average particle diameter 0.5 μm, specific surface area 4.1 m2 / g, density 3.9 x 10 2 6 g / m 3

[0113] B-2-1: spherical alumina, average particle diameter 2.1 μm, specific surface area 1.8 m2 / g, density 3.9 x 10 2 6 g / m 3

[0114] B-2-2: spherical alumina, average particle diameter 1.6 μm, specific surface area 1.1 m2 / g, density 3.9 x 10 2 6 g / m 3

[0115] B-3-1: spherical alumina, average particle diameter 18 μm, specific surface area 1 m2 / g, density 3.9 x 10 2 6 g / m 3

[0116] B-3-2: spherical alumina, average particle diameter 20.3 μm, specific surface area 0.2 m2 / g, density 3.9 x 10 2 6 g / m 3

[0117] (3) C component (curing catalyst (vulcanizing agent))

[0118] 50% paste of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane

[0119] Surface treatment of 2B component

[0120] Into a tank of a Henschel mixer, the B component (thermally conductive filler) to be treated was put, and a surface treatment liquid obtained by diluting the following silane coupling agent with 77% aqueous ethanol was added dropwise, and stirred for 5 minutes. After that, the filler was taken out from the tank and transferred to a metal-made container, and dried at 130°C for 2 hours with a hot air circulating oven. With respect to the B component (thermally conductive filler), the silane coupling agent was added in an amount obtained by the following calculation formula.

[0121] (Calculation formula)

[0122] ​​​​​​Silane coupling agent amount (g) = Filler weight (g) x Specific surface area of filler (m 2 / g) ÷ Minimum coating area of silane coupling agent (m 2 / g)

[0123] Minimum coating area of silane coupling agent (m 2 / g) = 6.02 x 10 23 x 13 x 10 -20 ÷ Molecular weight of silane coupling agent

[0124] • Surface treatment agent having a reaction group not containing an unsaturated bond: n-octyltrimethoxysilane (hereinafter abbreviated as "octyl").

[0125] • Surface treatment agent having a reaction group not containing an unsaturated bond: n-decyltrimethoxysilane (hereinafter abbreviated as "decyl").

[0126] • Surface treatment agent having a reaction group containing an unsaturated bond: 3-methacryloyloxypropyltrimethoxysilane (hereinafter abbreviated as "methacryloyloxy").

[0127] • Surface treatment agent having a reaction group containing an unsaturated bond: 7-octenyltrimethoxysilane (hereinafter abbreviated as "octenyl").

[0128] 3 Mixing treatment

[0129] The components shown in Table 3 below were put into a press kneader in the proportions of the specified weight parts, and mixed for 15 minutes.

[0130] After the mixing, the resulting mixture was taken out of the kneader, and a prescribed amount of curing catalyst (vulcanizing agent) was mixed therewith using an open roll to obtain the compound of the example.

[0131] 4 Production of cured sheet

[0132] The compound of the example was sandwiched between two sheets of polyethylene terephthalate (PET) film, and after being thinly calendered using a constant speed roll, the compound was cured by sandwiching the PET film in a heating press which was warmed to 170°C for 10 minutes, and the PET film on both sides was peeled off to obtain a cured sheet of the compound.

[0133] The results above are summarized in Table 3.

[0134]

[0135] As indicated by Table 3, each example was soft, was able to set the tensile strength to 5 MPa or more, was able to set the thermal conductivity to 1 W / m-K or more, and was a high strength which was sufficiently operable even without a reinforcing material sheet such as a glass fiber cloth.

[0136] In contrast, in Comparative Example 1 and Comparative Example 2, since the surface treatment of B-2 is not a surface treatment agent containing an alkenyl group, the tensile strength is less than 5 MPa. Further, in Comparative Example 3, since the surface treatment of B-1 is not a surface treatment agent not containing an alkenyl group, the plasticity exceeds 50. This is a problem in softness. In Comparative Example 4, even in the case of different fillers (different K values), since the surface treatment of B-2 is not a surface treatment agent containing an alkenyl group, the tensile strength is less than 5 MPa.

[0137] Industrial applicability

[0138] The heat-conductive silicone sheet of the present application is suitable for being interposed between a heat generating portion of an electrical / electronic component or the like and a heat sink.

[0139] Explanation of symbols

[0140] 1 Heat conductivity measuring device

[0141] 2 Sensor

[0142] 3a, 3b Test sample

[0143] 4 Front end of sensor

[0144] 5 Electrode for applying current

[0145] 6 Electrode for resistance value (temperature measuring electrode)

Claims

1. A heat conductive silicone composition comprising A to C below, A a linear organopolysiloxane having 1 reactive group at each of both molecular chain terminals, B a heat conductive filler comprising B-1, B-2 and B-3 below, 800 to 2500 parts by mass relative to 100 parts by mass of the A component, B-1 a heat conductive filler having an average particle diameter of 0.1 μm or more and less than 1.0 μm, and obtained by surface treatment with a silane coupling agent having a reactive group free of unsaturated bond, B-2 a heat conductive filler having an average particle diameter of 1.0 μm or more and less than 10 μm, and obtained by surface treatment with a silane coupling agent having a reactive group containing unsaturated bond, B-3 a heat conductive filler having an average particle diameter of 10 μm or more and 100 μm or less, and obtained by surface treatment with at least one selected from a silane coupling agent having the reactive group free of unsaturated bond or the reactive group containing unsaturated bond, C a curing catalyst: a catalytic amount.

2. The thermally conductive silicone composition according to claim 1, wherein, The silane coupling agent having the reactive group free of unsaturated bond is a silane coupling agent free of alkenyl group.

3. The thermally conductive silicone composition according to claim 1, wherein, The silane coupling agent having the reactive group free of unsaturated bond is a silane coupling agent containing alkyl group.

4. The thermally conductive silicone composition according to claim 1 or 2, wherein, The silane coupling agent having the reactive group containing unsaturated bond is at least one selected from silane coupling agents containing alkenyl group, acryl group, methacryl group, styryl group.

5. The thermally conductive silicone composition according to claim 1 or 2, wherein, The heat conductive silicone composition has a plasticity of 1 to 50 before curing.

6. The thermally conductive silicone composition according to claim 1 or 2, wherein, The linear organopolysiloxane of the A is represented by the following general formula (1), X[Si(CH3)2-O-]nSi(CH3)2-Y (1) wherein the polymerization degree n is in the range of 5 to 2100, and the terminal groups X and Y are vinyl groups. The mixing ratio of the B-1, B-2 and B-3 is (the total of the surface area of B-3 + the total of the surface area of B-2) = K x (the total of the cross-sectional area of B-1), and K = 1 to 5.

7. The thermally conductive silicone composition according to claim 1 or 2, wherein, The curing catalyst is an organic peroxide.

8. The thermally conductive silicone composition according to claim 1 or 2, wherein, The heat conductive filler of the B component is at least one selected from alumina, zinc oxide, silica, silicon carbide, aluminum nitride and boron nitride.

9. The thermally conductive silicone composition according to claim 1 or 2, wherein, When the A component is set to 100 parts by mass, the mixing ratio of the B-1, B-2 and B-3 is B-1: 150 to 450 parts by mass, B-2: 250 to 550 parts by mass, and B-3: 400 to 1500 parts by mass.

10. The thermally conductive silicone composition according to claim 1 or 2, wherein, It is a silicone sheet formed by sheet formation and heat curing of the heat conductive silicone composition described in any one of claims 1 to 10, and has a tensile strength of 5 MPa or more.

11. A thermally conductive silicone sheet, characterized by, The heat conductivity of the heat conductive silicone sheet is 1 W / m-K or more.

12. The thermally conductive silicone sheet according to claim 11, wherein, The heat conductive silicone sheet does not contain a reinforcing material sheet.

13. The thermally conductive silicone sheet of claim 11, wherein, The composition comprising the A to C components described in any one of claims 1 to 10 is uniformly mixed, subjected to sheet formation, and heat cured.

14. A method for producing a heat-conducting silicone sheet, characterized by ​

Images