Thermally softenable thermally conductive composition

Abstract

To provide a thermally softenable thermally conductive composition capable of achieving reduced viscosity during melting and reduced thermal resistance compared with conventional products.SOLUTION: A thermally softenable thermally conductive composition contains the following components (A), (B), and (C). (A) A phenyl-modified silicone resin containing 90-100 mol% of T units and D units in component (A) and having a phenyl modification ratio of 30-60 mol%. (B) A hydrolyzable organopolysiloxane represented by formula (1), in which R3 is an aryl group having 6-10 carbon atoms, R4 is an alkyl group having 1-10 carbon atoms, x is 2 or 3, n is a number satisfying 0≤n≤15, and m is a number satisfying 2≤m≤60. (C) A thermally conductive filler having a thermal conductivity of 10 W / (m K) or more and an average particle diameter of 0.3-20 μm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat-softenable thermally conductive composition. [Background technology]

[0002] In recent years, a number of heat-softening materials have been disclosed as thermally conductive materials that have the advantages of both thermally conductive sheets and thermally conductive greases. These materials are non-fluid at room temperature but soften or melt when heated to become fluid. However, thermosoftening materials that use organic substances as base oils (Patent Documents 1 to 4) have poor heat resistance, and there is concern that they will deteriorate due to high temperatures when used in automobiles and the like. To improve heat resistance, many silicone-based heat-softening materials have been disclosed (e.g., Patent Documents 5 and 6), including, for example, sheet-formed products and paste-like thermally conductive materials (which utilize a curing reaction). However, silicone has low thermal conductivity, and silicone-based thermosoftening materials have the problem of low thermal conductivity. To increase the thermal conductivity of the thermosoftening material, it is necessary to highly fill the thermosoftening material with a thermally conductive filler. However, simply filling the thermosoftening material with a high thermally conductive filler significantly increases the viscosity of the thermosoftening material. In particular, if the viscosity of the thermosoftening material is high in the heat-generating temperature range during operation of electronic components, the thermosoftening material will not thin easily even when compressed, resulting in increased thermal resistance. Therefore, a method has been proposed in which the surface of a thermally conductive filler is treated with a silane coupling agent (wetter) and then dispersed in a base thermosoftening silicone resin to maintain the fluidity of the thermosoftening material (Patent Document 7). However, silane coupling agents have poor compatibility with thermosoftening silicone resins and are unable to sufficiently reduce the viscosity of the thermosoftening material, making it impossible to obtain the desired thickness and heat resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-106283 [Patent Document 2] International Publication No. 2016 / 185936 [Patent Document 3] International Publication No. 2015 / 035575 [Patent Document 4] Patent Publication No. 2021-80316 [Patent Document 5] Japanese Patent Application Laid-Open No. 2016-76678 [Patent Document 6] Patent Publication No. 2021-147591 [Patent Document 7] Japanese Patent Application Laid-Open No. 2007-150349 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, an object of the present invention is to provide a heat-softenable thermally conductive composition that is used as a thermally conductive material (coating) to be interposed on the thermal boundary surface between a heat-generating electronic component and a heat-dissipating component such as a heat sink or metal housing for the purpose of cooling the electronic component, that reduces in viscosity, softens, or melts at temperatures within the operating temperature range of the electronic component, so that the thermally conductive material adheres closely to the thermal boundary surface, and that has a lower viscosity when melted and lower thermal resistance than conventional products. [Means for solving the problem]

[0005] As a result of extensive research conducted by the present inventors to solve the above problems, they discovered that by blending a specific hydrolyzable organopolysiloxane and a thermally conductive filler with a heat-softening phenyl-modified silicone resin, a heat-softening thermally conductive composition with low viscosity and low thermal resistance can be obtained, leading to the completion of the present invention.

[0006] That is, an object of the present invention is to provide a heat-softenable, thermally conductive composition containing the following components (A) to (C): Here, heat softening refers to softening, lowering viscosity, or melting due to heat (at 40°C or above), and a coating that is heat softened, lowered in viscosity, or melted and fluidizes on the surface is considered to have "heat softening."

[0007] [1] A heat-softenable, thermally conductive composition comprising the following components (A), (B), and (C): (A)R 1 SiO 3 / 2 Units (wherein R 1 is a group selected from an alkyl group having 1 to 10 carbon atoms and a phenyl group), and R 2 2SiO 2 / 2 Units (wherein R 2 is a group selected from an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and a phenyl group), in component (A), and a phenyl modification rate of 30 to 60 mol%: 100 parts by mass (B) a hydrolyzable organopolysiloxane represented by the following formula (1): 10 to 100 parts by mass per 100 parts by mass of component (A): [ka] (In formula (1), R 3 is an aryl group having 6 to 10 carbon atoms, and R 4 is an alkyl group having 1 to 10 carbon atoms; x is 2 or 3; n is a number satisfying 0≦n≦15; and m is a number satisfying 2≦m≦60. (C) a thermally conductive filler having a thermal conductivity of 10 W / (m·K) or more and an average particle size of 0.3 to 20 μm: 1,000 to 1,700 parts by mass per 100 parts by mass of component (A) [2] In formula (1), R 3 is a phenyl group, and R 4 The heat-softenable, thermally conductive composition according to [1], which contains a hydrolyzable organopolysiloxane in which is a methyl group. [3] A cured product of the heat-softenable thermally conductive composition according to [1] or [2]. [Effects of the Invention]

[0008] The heat-softenable thermally conductive composition of the present invention has a lower viscosity when melted than conventional products and is excellent in thermal conductivity. Furthermore, the heat-softenable thermally conductive composition of the present invention is disposed between a heat-generating electronic component and a heat-dissipating component, has no fluidity at room temperature, and becomes less viscous, softens, or melts due to heat generated during operation of the electronic component, thereby substantially filling the boundary between the electronic component and the heat-dissipating component. Therefore, the heat-softenable thermally conductive composition of the present invention is useful as a heat-dissipating material. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below.

[0010] (A) Phenyl-modified silicone resin Component (A) is a heat-softening phenyl-modified silicone resin that forms the matrix of the composition (heat dissipation member) of the present invention. Component (A) is a silicone resin that is substantially non-fluid at room temperature, but that heat-softens, reduces viscosity, or melts and becomes fluid when the heat-generating electronic component generates heat, specifically in the temperature range of 40 to 80°C. Component (A) heat-softens the composition (heat dissipation member) of the present invention and also functions as a binder that imparts processability and workability to the filler that imparts thermal conductivity. In the present invention, "room temperature" refers to a range of 10 to 30°C. Here, the temperature at which the silicone resin softens, reduces viscosity, or melts is the temperature required for the heat dissipation component, and the melting point of the silicone resin itself is preferably 40 to 80°C, and particularly preferably 50 to 70°C. If the melting point of the silicone resin itself is less than 40°C, the surface layer may become tacky when the composition is applied, making it difficult to handle. If the melting point of the silicone resin itself is higher than 80°C, the temperature during heat compression must be high, which may make the mounting process difficult.

[0011] Component (A) is R 1 SiO3 / 2 unit (hereinafter referred to as T unit), and R 2 2SiO 2 / 2 In addition to these T units and D units, component (A) also contains R 2 3SiO 1 / 2 It may also have a small amount of units (hereinafter referred to as M units). R 1 is a group selected from an alkyl group having 1 to 10 carbon atoms and a phenyl group. 1 Specific examples of R include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl, and phenyl groups. 1 is preferably a methyl group or a phenyl group. R 2 is the above R 1 In addition to the alkyl groups and phenyl groups, R is a group selected from alkenyl groups having 2 to 10 carbon atoms. 2 A specific example of this is R 1 In addition to the above, specific examples include alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexynyl, and octenyl. Among these, from the viewpoint of flame retardancy, R 2 is preferably a methyl group, a phenyl group, a vinyl group or an allyl group.

[0012] The silicone resin of component (A) will now be described in more detail. To be non-fluid at room temperature, the silicone resin of component (A) must contain a certain proportion of T units and D units. The content of T units and D units in component (A) is 90 to 100 mol %, preferably 93 to 100 mol %, and particularly preferably 96 to 100 mol %. The silicone resin may also be composed of a combination (mol %) of T units, D units, and a small amount of M units. Introducing T units increases toughness and reduces brittleness when solid at room temperature, preventing breakage during handling. Introducing D units also improves toughness at room temperature. M units form terminals. In silicone resins consisting of a combination of M units, T units, and D units, the ratio of T units to D units is preferably 10:90 to 90:10, and more preferably 20:80 to 80:20. The ratio of M units to (T units + D units) is preferably 0.2:100 to 4:100.

[0013] The phenyl modification rate of the silicone resin of component (A) is 30 to 60 mol%, preferably 40 to 60 mol%, and particularly preferably 50 to 60 mol%. If the phenyl modification rate is less than 30 mol%, the heat softening properties of the resin will decrease, and it may be difficult to achieve a thin thickness. If the phenyl modification rate exceeds 60 mol%, the compatibility of the wetter with component (B) will decrease, and it may be difficult to uniformly disperse the thermally conductive filler. The phenyl modification rate is the ratio of units containing phenyl groups among M units, D units, and T units, expressed as a molar percentage.

[0014] Specific examples of component (A) include silicone resins having a specific composition of difunctional structural units (D units) and trifunctional structural units (T units) as shown below. Note that the bonding order of the siloxane units listed below may be either block or random. D m Tφ p D Vi n (where D is a dimethylsiloxy unit (i.e., (CH3)2SiO 2 / 2 ), Tφ is a phenylsiloxy unit (i.e., (C6H5)SiO 3 / 2 ), D Vi is a methylvinylsiloxy unit (i.e., (CH3)(CH2=CH)SiO 2 / 2 ), where p / (m+p+n) (molar ratio) is 0.3 to 0.6, and n / (m+n) (molar ratio) is 0.7 to 1.0.

[0015] Specific examples of component (A) include silicone resins having a specific composition of monofunctional structural units (M units), difunctional structural units (D units), and trifunctional structural units (T units), as shown below. M L D m Tφ p D Vi in (where M is a trimethylsiloxy unit (i.e., (CH3)3SiO 1 / 2 ), and D, Tφ and D Vi are as described above, and p / (m+p+n+L) (molar ratio) = 0.3 to 0.6, n / (m+n) (molar ratio) = 0.7 to 1.0, L / (m+n) (molar ratio) = 0.001 to 0.1.

[0016] How to measure M-unit, D-unit, and T-unit ratios In the present invention, the monofunctional R 1 3SiO 1 / 2 Unit (M unit), bifunctional R 2 SiO 2 / 2 Unit (D unit), trifunctional R 1 SiO 3 / 2 The ratio of units (T units) is 29 This is a value obtained from Si-NMR. 29 The method for preparing a Si-NMR sample is not particularly limited, but for example, a sample can be prepared by dissolving 1 part by mass of organopolysiloxane resin in 3 parts by mass of deuterated chloroform. The average degree of polymerization of the silicone resin, i.e., the total amount of M units, D units, T units, and Q units, is preferably 30 to 300, more preferably 50 to 150. In the present invention, the average degree of polymerization is a value determined as a polystyrene-equivalent number-average degree of polymerization (number-average molecular weight) in GPC (gel permeation chromatography) analysis using toluene as a developing solvent.

[0017] [Measurement conditions] Developing solvent: toluene Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) TSKgel SuperH2000(6.0mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 10 μL (0.5 wt% toluene solution)

[0018] The component (A) may be used alone or in combination of two or more types. The content of component (A) in the composition of the present invention is preferably 5 to 10 mass %, more preferably 6 to 7 mass %.

[0019] (B) Hydrolyzable organopolysiloxane Component (B) is a hydrolyzable organopolysiloxane represented by the following formula (1), and serves as a surface treatment agent (wetter) for component (C), which will be described later. Component (B) hydrophobizes component (C) during the preparation of the composition, improving wettability with component (A) and enabling component (C) to be uniformly dispersed in component (A). [ka] (In formula (1), R 3 is an aryl group having 6 to 10 carbon atoms, and R 4 is an alkyl group having 1 to 10 carbon atoms; x is 2 or 3; n is a number satisfying 0≦n≦15; and m is a number satisfying 2≦m≦60.

[0020] In the above formula (1), R 3 is an aryl group having 6 to 10 carbon atoms. 3Specific examples of include aryl groups such as phenyl, tolyl, xylyl, and mesityl groups, and among these, phenyl is preferred from the viewpoint of ease of synthesis. In the above formula (1), R 4 is an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms. 4 Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, octyl, nonyl, and decyl groups, with methyl and ethyl groups being particularly preferred. In the above formula (1), x is 2 or 3. If x is 1, the hydrophobic treatment is insufficient, and the component (C) cannot be uniformly dispersed in the component (A). In the above formula (1), n ​​is a number satisfying 0≦n≦15, more preferably 0≦n≦8, and even more preferably 0≦n≦5. In the above formula (1), m is a number satisfying 2≦m≦60, more preferably a number satisfying 9≦m≦30, and even more preferably a number satisfying 12≦m≦18. If the amount is outside the above range, the compatibility with the phenyl-modified silicone resin, which is component (A), decreases, and the ability to function as a dispersant decreases, which is undesirable.

[0021] Specific examples of component (B) include organopolysiloxanes with the following structures: [ka]

[0022] The blending amount of component (B) is 10 to 100 parts by mass, preferably 20 to 70 parts by mass, and more preferably 30 to 60 parts by mass per 100 parts by mass of component (A). If the blending amount is less than 10 parts by mass, the hydrophobization treatment may be insufficient, and component (C) may not be uniformly dispersed in component (A). If the blending amount is more than 100 parts by mass, the composition may be less likely to become non-fluid at room temperature, and pump-out resistance may be reduced.

[0023] (C) Thermally conductive filler The thermally conductive filler of component (C) must have a thermal conductivity of 10 W / (m K) or more. If the thermal conductivity is less than 10 W / (m K), the thermal conductivity of the heat-softenable thermally conductive composition itself will be low. The upper limit of thermal conductivity varies depending on the material used for the thermally conductive filler, but there is no specific upper limit. Examples of thermally conductive fillers having a thermal conductivity of 10 W / (m·K) or more include powders and granules such as aluminum powder, copper powder, silver powder, nickel powder, gold powder, alumina powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, boron nitride powder, silicon nitride powder, diamond powder, and carbon powder, and these may be used alone or in combination of two or more.

[0024] When a powder or granule is used as the thermally conductive filler, its shape may be irregular, spherical, or any other shape, but the average particle size is 0.3 to 20 μm, preferably 1 to 15 μm. If the average particle size is less than 0.3 μm, the compoundability of the composition decreases and extensibility becomes poor, while if it exceeds 20 μm, it may be difficult to reduce the thickness after heat compression. The above average particle size is determined by measuring the cumulative volume average diameter D 50 Specifically, the cumulative 50% particle diameter (D) on a volume basis measured using a particle size distribution analyzer MT3000II manufactured by Microtrac Bell Co., Ltd. 50 ) (the same applies below). The amount of the thermally conductive filler blended is in the range of 800 to 1,300 parts by mass, and preferably in the range of 900 to 1,200 parts by mass, per 100 parts by mass of component (A). If the blending amount is less than 800 parts by mass, the required thermal conductivity cannot be obtained, and if it exceeds 1,300 parts by mass, the blendability of the composition decreases and extensibility may become poor.

[0025] (Other additives) The thermally conductive composition of the present invention may further contain additives, fillers, and the like as optional components, provided that the purpose of the present invention is not impaired. Specifically, phenyl-modified silicone oil may be added as a plasticizer (component (D)); carbon black, red iron oxide, or the like as a colorant; and platinum catalysts, metal oxides such as iron oxide, titanium oxide, and cerium oxide, or metal hydroxides may be added as flame retardants. Furthermore, a solvent may be added to form a liquid grease for application by a highly efficient mass-production method, such as dispense application, screen printing, or coating. Specific examples of such solvents include toluene, xylene, and isoparaffin-based solvents.

[0026] (Manufacturing method) The heat-softening thermally conductive composition used in the heat dissipation member of the present invention can be easily produced by blending and kneading the above-mentioned components (A), (B), and (C), as well as other components (e.g., component (D)), using a rubber kneader such as a kneader, gate mixer, or planetary mixer. Heating may be performed as needed. The resulting composition can be diluted with an appropriate amount of toluene or an isoparaffin-based solvent to form a paste-like heat-softening thermally conductive composition suitable for application by screen printing, coating, or the like. Furthermore, when producing a sheet-like heat-softening thermally conductive composition, the paste-like heat-softening thermally conductive composition can be coated onto a PET (polyethylene terephthalate) release film, heated in a drying oven at 80°C to 120°C for approximately 30 minutes to volatilize the solvent, and then a PET release film can be laminated onto the coated film using a heated roll.

[0027] Properties after heat compression When the resulting heat-softenable thermally conductive composition after drying is heated and compressed at 50°C for 30 minutes under a pressure of 0.7 kPa, it can be compressed to a thickness of 60 μm or less, preferably 50 μm or less, and particularly preferably 40 μm or less. The heat resistance of the obtained heat-softening thermally conductive composition after drying is 20 to 50 μm thick and 10 mm thick. 2 ·K / W or less is preferable, and 7mm2 The effective thermal resistance was calculated using the following formula based on the thermal conductivity determined by the laser flash method and the thickness of the sample.

number

[0028] (2) Complex viscosity The heat dissipation member of the present invention preferably has a complex viscosity of 900 to 10,000 Pa·s, and more preferably 1,500 to 8,000 Pa·s, at 50°C and a frequency of 10 Hz. When the complex viscosity is within this range, the thermosoftenable thermally conductive composition is less likely to flow out from between the electronic component and the heat dissipation component such as a heat sink (good pump-out resistance), and it is easier to reduce the gap between the electronic component and the heat dissipation component, making it easier to achieve sufficient heat dissipation performance. [Example]

[0029] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0030] The components (A) to (D) constituting the heat-softenable thermally conductive materials used in the following examples and comparative examples are as follows. In the following, M represents a trimethylsiloxy unit (i.e., (CH3)3SiO 1 / 2 ), D is a dimethylsiloxy unit (i.e., (CH3)2SiO 2 / 2 ), Dφ is a diphenylsiloxy unit (i.e., (C6H5)2SiO 2 / 2 ), D Vi is a methylvinylsiloxy unit (i.e., (CH3)(CH2=CH)SiO 2 / 2 ), Tφ is a phenylsiloxy unit (i.e., (C6H5)SiO 3 / 2 ) In addition, Me represents a methyl group, and Ph represents a phenyl group.

[0031] (A) Component: Phenyl-modified silicone resin (A-1) Silicone resin (average degree of polymerization: 100) represented by the following formula and having a phenyl modification rate of 55 mol% D 25 Tφ 55 D Vi 20 (A-2) Silicone resin (average polymerization degree: 100) represented by the following formula and having a phenyl modification rate of 73 mol% (for comparison) M 15 D 12 (Dφ) 22 Tφ 51 (A-3) Silicone resin (average degree of polymerization: 100) represented by the following formula and having a phenyl modification rate of 20 mol% (for comparison) D 80 Tφ 20

[0032] Component (B): Hydrolyzable organopolysiloxane (B-1) Hydrolyzable organosiloxane represented by the following formula (3): [ka] (B-2) Hydrolyzable organosiloxane represented by the following formula (4): [ka] (B-3) Hydrolyzable organosiloxane represented by the following formula (5) (for comparison) [ka] (B-4) Hydrolyzable organosiloxane represented by the following formula (6): [ka] (B-5) Hydrolyzable organosiloxane represented by the following formula (7) (for comparison) [ka] (B-6) Hydrolyzable organosiloxane represented by the following formula (8): [ka] (B-7) Hydrolyzable organosiloxane represented by the following formula (9) (for comparison) [ka]

[0033] (C) Component: Thermally conductive filler (C-1) Zinc oxide powder: average particle size 1.0 μm (thermal conductivity: 54 W / (m·K)) (C-2) Aluminum powder: average particle size 2 μm (thermal conductivity: 236 W / (m·K)) (C-3) Aluminum powder: average particle size 10 μm (thermal conductivity: 236 W / (m·K)) (C-4) Aluminum powder: average particle size 30 μm (thermal conductivity: 236 W / (m·K)) (for comparison)

[0034] (D) Component: Plasticizer An organopolysiloxane represented by the following formula (10): [ka]

[0035] The above components (A), (B), (C), and (D) were charged into a planetary mixer in the amounts shown in Tables 1 and 2 below and mixed for 60 minutes to produce the heat-softenable thermally conductive compositions of Examples 1 to 6 and Comparative Examples 1 to 9. Five parts by mass of toluene was added to 100 parts by mass of the obtained composition to dilute it, and the paste-like heat-softenable thermally conductive composition was then dried to a thickness of 200 μm, yielding heat-softenable thermally conductive compositions (a) to (o). The properties of the obtained heat-softenable thermally conductive compositions are also shown in Tables 1 and 2.

[0036] (Evaluation method) (1) Thickness, thermal resistance and thermal conductivity The obtained heat-softenable thermally conductive composition was sandwiched between two circular standard aluminum plates (purity: 99.99%, diameter: approximately 12.7 mm, thickness: approximately 1.0 mm) and heated and compressed at 50°C for 30 minutes under a pressure of 0.7 kPa to obtain a sample having a heat dissipation member between the two aluminum plates. Next, the thickness of each of the two standard aluminum plates was measured, and the actual thickness of the heat dissipation member was measured by subtracting the previously known thickness of the standard aluminum plates. A micrometer (manufactured by Mitutoyo Corporation, model number: M820-25VA) was used to measure the thickness. The thermal resistance and thermal conductivity of the heat dissipation member were measured using a laser flash measuring instrument (LFA467HyperFlash, manufactured by NETZSCH). The results are shown in Tables 1 and 2.

[0037] (2) Complex viscosity The complex viscosity of the heat dissipation member at 50°C was measured using a viscoelasticity measuring device, HAAKE MARS40 (trade name, manufactured by Thermo Fisher Scientific). The measurement was performed under strain control, with the strain set to 1%. A parallel plate (P20 / Ti) was used as the sensor. The results of the complex viscosity at 50°C and a frequency of 10 Hz are shown in Tables 1 and 2.

[0038] <Examples 1 to 6> Using compositions (a) to (f), sheet-shaped heat-softenable thermally conductive compositions were obtained by the method described above. <Comparative Example 1> A sheet-shaped heat-softenable thermally conductive composition was obtained using composition (g). Even when heated and compressed, the thickness did not decrease and the thermal resistance was high. <Comparative Example 2> Composition (h) was used to obtain a sheet-shaped heat-softenable thermally conductive composition. It was fluid at room temperature and had a low complex viscosity at 50°C. <Comparative Example 3> Composition (i) did not become grease-like even after blending, so its physical properties could not be evaluated. <Comparative Example 4> Composition (j) did not become grease-like even after blending, so its physical properties could not be evaluated. <Comparative Example 5> Composition (k) did not become grease-like even after blending, so its physical properties could not be evaluated. <Comparative Example 6> Composition (l) did not become grease-like even after blending, so its physical properties could not be evaluated. <Comparative Example 7> A sheet-shaped heat-softenable thermally conductive composition was obtained using composition (m), which was fluid at room temperature and had a low complex viscosity at 50°C. <Comparative Example 8> Composition (n) did not become grease-like even after blending, so its physical properties could not be evaluated. <Comparative Example 9> A sheet-shaped heat-softenable thermally conductive composition was obtained using composition (o). Even when heated and compressed, the thickness did not decrease and the thermal resistance was high.

[0039] [Table 1]

[0040] [Table 2]

Claims

1. A heat-softenable, thermally conductive composition comprising the following components (A), (B), and (C): (A)R 1 SiO 3 / 2 Units (wherein R 1 is a group selected from an alkyl group having 1 to 10 carbon atoms and a phenyl group), and R 2 2 SiO 2 / 2 Units (wherein R 2 is a group selected from an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and a phenyl group), in an amount of 90 to 100 mol % in component (A), and a phenyl modification rate of 30 to 60 mol %: 100 parts by mass (B) a hydrolyzable organopolysiloxane represented by the following formula (1): 10 to 100 parts by mass per 100 parts by mass of component (A): 【Chemistry 1】 (In formula (1), R 3 is an aryl group having 6 to 10 carbon atoms, and R 4 is an alkyl group having 1 to 10 carbon atoms; x is 2 or 3; n is a number in the range of 0≦n≦15; and m is a number in the range of 2≦m≦60. (C) a thermally conductive filler having a thermal conductivity of 10 W / (m·K) or more and an average particle size of 0.3 to 20 μm: 1,000 to 1,700 parts by mass per 100 parts by mass of component (A);

2. In formula (1), R 3 is a phenyl group, and R 4 2. The heat-softenable, thermally conductive composition of claim 1, comprising a hydrolyzable organopolysiloxane in which is a methyl group.

3. A cured product of the heat-softenable thermally conductive composition according to claim 1 or 2.

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