Thermally conductive composite silicone sheet

Abstract

The present invention provides a thermally conductive composite silicone sheet that can be given adhesive properties, allows for selection of the adhesive surface, offers high productivity, and has high thermal conductivity. [Solution] A thermally conductive composite silicone sheet having a thermally conductive silicone rubber sheet and a thermally softening phenyl silicone gel layer disposed on one or both sides of the thermally conductive silicone rubber sheet, the following (A) to (D): (A) Phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a phenyl modification rate of 50% or more: 100 parts by mass (B) Organohydrogenpolysiloxane: an amount such that the number of moles of hydrosilyl groups of component (B) is 0.1 to 3 moles per mole of alkenyl groups of component (A) (C) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms relative to the mass of component (A) (D) Non-reactive phenyl-modified organopolysiloxane: 1 to 50 parts by mass relative to component (A)

Description

[Technical Field]

[0001] This invention relates to a thermally conductive composite silicone sheet. [Background technology]

[0002] As electrical and electronic equipment continues to become smaller and more highly integrated, the effects of heat generated by electrical and electronic components such as power semiconductors and memory are becoming more serious than ever before. When heat accumulates in electrical and electronic components, their temperature rises, potentially causing malfunctions or failures. To prevent such problems, many heat dissipation methods and heat dissipation materials have been proposed to efficiently dissipate the heat generated from electronic components to cooling materials such as heat sinks.

[0003] Conventionally, in electrical and electronic equipment, heat sinks made of metal plates with high thermal conductivity, such as aluminum or copper, have been used to suppress the temperature rise of components during operation. Heat sinks conduct heat generated from the components and release that heat from the surface due to the temperature difference with the surrounding air.

[0004] If the heat-generating element and the heat sink are placed in direct contact, air will be present at the interface, hindering heat conduction. Therefore, the heat sink must be in close contact with the element. Due to differences in height and tolerances during assembly, flexible and thermally conductive sheets or greases are used.

[0005] In particular, highly thermally conductive sheets are required for electrical and electronic equipment that generates a large amount of heat. It is known that a highly thermally conductive sheet can be obtained by creating a molded body in which anisotropic fillers such as carbon fibers are dispersed in a polymer matrix component, and the anisotropic fillers are oriented in the thickness direction, and then slicing the resulting molded body perpendicular to the anisotropic filler orientation direction (Patent Document 1).

[0006] However, in order to improve the workability of mounting and fixing, adhesive properties that allow for temporary fixing are sometimes required on one or both sides of the thermal conductive sheet. However, thermal conductive sheets manufactured by the above method lack adhesive properties on the sheet surface, resulting in a problem of poor workability during mounting and fixing.

[0007] To solve this problem, it has been proposed to impart tackiness to a thermally conductive silicone rubber sheet by providing a thermo-softening silicone resin layer with a thickness of 0.5 to 10 μm (Patent Document 2). However, in a thermally conductive silicone rubber sheet where the fillers are oriented in the thickness direction by creating a molded body in which carbon fibers in a thermally conductive resin composition are oriented and then slicing the resulting molded body perpendicular to the anisotropic filler orientation direction, there was a problem in that the silicone resin layer could not be compounded.

[0008] To solve this problem, a proposal has been made to improve the workability of mounting and fixing by pressing a thermally conductive sheet in which carbon fibers are oriented in the thickness direction, and forming a resin coating layer covered with the uncured component of the polymer matrix, thereby imparting tackiness (Patent Document 3). However, this method has the problem that the orientation of the carbon fibers collapses when the sheet becomes thicker during pressing, and that it is not possible to choose to impart tackiness to only one side of the thermally conductive sheet.

[0009] Furthermore, a thermal conductive sheet has been proposed that eliminates the need for a slicing process by injecting a mixture of a silicone resin matrix and a thermal conductive filler containing carbon fibers into a mold of a desired thickness and applying a magnetic field in the thickness direction, thereby orienting the carbon fibers in the sheet thickness direction and providing an adhesive skin layer on both sides (Patent Document 4). In addition, it has been proposed to form an oxide layer by irradiating one side of the skin layer of the thermal conductive sheet with vacuum ultraviolet light to suppress adhesiveness and obtain a thermal conductive sheet that is adhesive on only one side. However, this method has the problem of low productivity and high cost because it is necessary to manufacture the thermal conductive sheet in single sheets. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2023-120623 [Patent Document 2] Japanese Patent Publication No. 2020-203457 [Patent Document 3] Japanese Patent Publication No. 2020-129628 [Patent Document 4] International Publication No. 2021 / 025089 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The present invention was made to solve the above problems, and aims to provide a thermally conductive composite silicone sheet that can be given tackiness by providing a thin film of thermosoftening phenyl silicone gel layer on one or both sides of a thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, and on which the tackiness-giving surface can be selected, has high productivity and high thermal conductivity. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides: A thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, A thermosoftening phenyl silicone gel layer containing the following components (A) to (D) is disposed on one or both sides of the thermally conductive silicone rubber sheet. The present invention provides a thermally conductive composite silicone sheet characterized by having [a certain property]. (A) Phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a phenyl modification rate of 50% or more: 100 parts by mass (B) Organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain: an amount such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles for every 1 mole of alkenyl groups in component (A) above. (C) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms with respect to the mass of the component (A) (D) Non-reactive phenyl-modified organopolysiloxane: 1 to 50 parts by mass

[0013] Such a thermally conductive composite silicone sheet can impart adhesiveness, and the adhesive-imparting surface can be selected, resulting in a thermally conductive composite silicone sheet with high productivity and high thermal conductivity, which is preferable.

[0014] The thickness of the thermoplastic phenyl silicone gel layer is preferably 15 μm to 100 μm.

[0015] With such a thickness, it can follow the unevenness on the surface of the thermally conductive silicone rubber sheet, so it can be efficiently transferred and compounded, and the adhesiveness is also good, which is preferable.

[0016] The thermoplastic phenyl silicone gel layer preferably contains the following components (E) and (F). (E) Organopolysiloxane having a hydrolyzable functional group or an alkoxysilane compound which is the component (E-3) represented by the following formula (3): 1 to 100 parts by mass R 1 a R 2 b Si(OR 3 ) 4-a-b (3) (In the formula, R 1 is independently an alkyl group having 6 to 15 carbon atoms, R 2 is independently a monovalent hydrocarbon group having 1 to 15 carbon atoms, R 3 is independently an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, provided that a + b is an integer of 1 to 3.) (F) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, and carbon: an amount that is 10 to 95% by mass based on the whole composition

[0017] The inclusion of such component (E) ensures sufficient surface treatment of the thermally conductive filler, and the inclusion of component (F) provides thermal conductivity, making it preferable.

[0018] The organopolysiloxane having a hydrolyzable functional group of component (E) above is component (E-1) represented by the following formula (1). [ka] (In the formula, R 4 These are independently aromatic hydrocarbon groups having 6 to 10 carbon atoms, R 5 R is an alkyl group having 1 to 10 carbon atoms, independently. 6 (where a is an alkyl group with 1 to 4 carbon atoms, a is 2 or 3, and n is an integer between 2 and 60.) And the (E-2) component represented by the following equation (2) [ka] (In the formula, R 7 These are independently monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms, R 8 R is an alkyl group having 1 to 10 carbon atoms, independently. 9 (where b is an alkyl group having 1 to 4 carbon atoms, b is 2 or 3, p is an integer between 1 and 30, and q is an integer between 0 and 60, provided that 3 is equal to or equal to p + q is equal to or equal to 90.) It is preferable that it be selected from among

[0019] Such (E-1) and (E-2) components are preferred as component (E).

[0020] The aforementioned thermally conductive composite silicone sheet can have adhesive properties that allow it to be fixed to the vertical surface of the AL plate for more than one hour.

[0021] The aforementioned thermally conductive composite silicone sheet preferably has such adhesive properties.

[0022] The thermal resistance of the thermosoftening silicone gel layer was measured at 20% compression and a measurement temperature of 50°C using a TIM-Tester compliant with ASTM D 5470, and the result was 0.2 cm². 2 It is preferable that the value is kW or less.

[0023] Thermal resistance is 0.2 cm 2 If the wattage is kW or less, the increase in thermal resistance when tackiness is imparted to the thermally conductive composite silicone sheet of the present invention can be minimized. [Effects of the Invention]

[0024] As described above, with the thermally conductive composite silicone sheet of the present invention, tackiness can be imparted by providing a thin film of thermosoftening silicone gel layer on one or both sides of a thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, and the tackiness-imparting surface can be selected, making it possible to provide a thermally conductive composite sheet with high productivity and high thermal conductivity. [Modes for carrying out the invention]

[0025] As described above, there was a need for the development of a thermally conductive composite silicone sheet that could be given adhesive properties, had a selectable adhesive surface, was highly productive, and had high thermal conductivity.

[0026] As a result of diligent research into the above-mentioned problems, the inventors of the present invention have found that the above-mentioned problems can be solved by a thermally conductive composite silicone sheet having a thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, and a thermally softening phenyl silicone gel layer containing the following components (A) to (D) arranged on one or both sides of the thermally conductive silicone rubber sheet, and have completed the present invention.

[0027] In other words, the present invention is A thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, A thermosoftening phenyl silicone gel layer containing the following components (A) to (D) is disposed on one or both sides of the thermally conductive silicone rubber sheet. This is a thermally conductive composite silicone sheet characterized by having [a certain property]. (A) Phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a phenyl modification rate of 50% or more: 100 parts by mass (B) Organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain: an amount such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles for every 1 mole of alkenyl groups in component (A) above. (C) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms relative to the mass of component (A) above. (D) Non-reactive phenyl-modified organopolysiloxane: 1 to 50 parts by mass

[0028] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0029] [Thermally conductive silicone rubber sheet] The thermally conductive silicone rubber sheet of the present invention is a thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction. For example, a carbon fiber-containing organopolysiloxane composition is made by adding one or more thermally conductive fillers, with carbon fibers as an essential component, and a curing agent to a silicone polymer and kneading the mixture. A molded body is then created in which the carbon fibers are oriented in a certain direction by any method, and the resulting molded body is sliced ​​perpendicular to the carbon fiber orientation direction to obtain a thermally conductive silicone rubber sheet in which the carbon fibers are oriented in the thickness direction of the sheet.

[0030] [Thermo-softening silicone gel layer] The thermo-softening silicone gel layer of the thermo-conductive composite silicone sheet of the present invention is a cured product of a thermo-softening thermo-conductive silicone composition containing the following components (A) to (D). Thermo-softening refers to the process of becoming less viscous and more fluid when heated from room temperature (25°C). That is, when the thermo-softening silicone is heated, it softens and becomes fluid, allowing it to conform to the unevenness of the thermo-conductive silicone rubber sheet. Furthermore, because of the strong interaction between the phenyl groups in the thermo-softening layer and the benzene rings constituting the carbon fibers contained in the thermo-conductive silicone rubber sheet, efficient transfer and composite formation can be achieved in a short time. (A) Phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a phenyl modification rate of 50% or more: 100 parts by mass (B) Organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain: The number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles for every 1 mole of alkenyl groups in component (A) above. (C) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms relative to the mass of component (A) above. (D) Non-reactive phenyl-modified organopolysiloxane 1 to 50 parts by mass relative to component (A) above

[0031] The heat-softening phenylsilicone gel layer is preferably 15 μm to 100 μm thick, more preferably 15 μm to 50 μm thick.

[0032] With this thickness, it can conform to the uneven surface of the thermally conductive silicone rubber sheet, allowing for efficient transfer and compounding, while also providing good adhesion. Furthermore, it can suppress the increase in the thermal resistance of the thermally conductive composite silicone sheet.

[0033] The components (A) to (D) above are explained below.

[0034] [(A) Phenyl-modified organopolysiloxane] Component (A) is a phenyl-modified organopolysiloxane having two or more, preferably 2 to 10, more preferably 2 to 5, alkenyl groups in the molecule. The main chain is preferably composed of diorganosiloxane units and is a linear organopolysiloxane.

[0035] The alkenyl group is preferably an alkenyl group having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. Examples include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, and octenyl groups. The vinyl group is particularly preferred. The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, a silicon atom in the middle of the molecular chain, or both.

[0036] Furthermore, the phenyl-modified organopolysiloxane of component (A) preferably has 0.0000001 to 0.005 mol / g, and particularly 0.00001 to 0.005 mol / g, of alkenyl groups per molecule.

[0037] Furthermore, component (A) is characterized by having a phenyl group. Preferably, the amount of phenyl groups in one molecule is such that the number of siloxane units containing a phenyl group per total siloxane unit is 50 to 100%. If the amount of phenyl groups in one molecule is less than 50% of the siloxane units, the interaction between the cured product and the benzene rings constituting the carbon fibers contained in the thermally conductive silicone rubber sheet decreases.

[0038] Furthermore, the phenyl group may be included at either the terminal or side chain.

[0039] Furthermore, from the viewpoint of viscosity, groups other than the alkenyl group and phenyl group are preferably alkyl groups having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. Note that alkyl groups in which some of the hydrogen atoms are substituted with halogen atoms may also be used. Methyl groups are particularly preferred as alkyl groups.

[0040] The phenyl-modified organopolysiloxane may be used alone or in combination of two or more types.

[0041] [(B) Organohydrogenpolysiloxane] Component (B) is an organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain, preferably 0 to 10 hydrosilyl groups, more preferably 0 to 4 hydrosilyl groups in the side chain. It can be used if it can undergo an addition reaction with the alkenyl group of component (A) in the presence of the platinum group metal catalyst (C) described later to form a sylalkylene structure.

[0042] The organohydrogenpolysiloxane described above is not particularly limited in its molecular structure as long as it possesses the above properties, and examples include linear structures, branched structures, partially branched structures, or linear structures having a cyclic structure. A linear structure is preferred.

[0043] The organic group bonded to the silicon atom of the organohydrogenpolysiloxane preferably includes a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and preferably does not include groups that have hydrosilylation reactivity, such as alkenyl groups or alkynyl groups.

[0044] Furthermore, groups other than the monovalent aromatic hydrocarbon group are preferably alkyl groups, and alkyl groups having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, are preferred. Examples include methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups. It is also possible to use alkyl groups in which some of the hydrogen atoms are substituted with halogen atoms. Among these, the methyl group is preferred.

[0045] The organohydrogenpolysiloxane may be used alone or in combination of two or more types.

[0046] The amount of organohydrogenpolysiloxane in component (B) is such that the number of hydrosilyl groups in component (B) is 0.1 to 3 relative to the total number of alkenyl groups in component (A), preferably 0.7 to 3, and more preferably 0.5 to 2. If the amount of component (B) is less than the lower limit, the addition reaction will not proceed sufficiently, resulting in insufficient crosslinking. If it exceeds the upper limit, the crosslinking structure may become non-uniform, or the stability of the composition over time may deteriorate.

[0047] [(C) Platinum group metal catalyst] Component (C) is a platinum group metal catalyst that functions to promote the addition reaction of the components described above. Conventional platinum group metal catalysts used in addition reactions can be used. Examples include platinum-based, palladium-based, and rhodium-based catalysts, but platinum or platinum compounds, which are relatively easy to obtain, are preferred. Examples include elemental platinum, platinum black, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, and platinum coordination compounds. A single platinum group metal catalyst or a combination of two or more may be used.

[0048] The amount of component (C) is 0.01 to 1,000 ppm, preferably 10 to 1,000 ppm, based on the mass of platinum group metal atoms relative to the mass of component (A). If the amount of catalyst is less than the lower limit, the catalytic effect may not be obtained. Conversely, exceeding the upper limit does not increase the catalytic effect and is uneconomical, so it is undesirable.

[0049] [(D) Non-reactive phenyl-modified organopolysiloxane] Component (D) is a non-reactive phenyl-modified organopolysiloxane that, in addition to the above components, does not undergo hydrosilylation reactions with components (A) and (B). The molecular structure of the non-reactive phenyl-modified organopolypolysiloxane is not particularly limited as long as it has the above properties, and examples include linear structures, branched structures, partially branched structures, or linear structures having a cyclic structure. A linear structure is preferred.

[0050] Furthermore, the aforementioned component is characterized by having a phenyl group. The amount of phenyl groups in one molecule is preferably 10-100%, and more preferably 30% or more, of the siloxane units containing a phenyl group per side-chain siloxane unit. If the amount of phenyl groups in one molecule is 10% or more relative to the side-chain siloxane units, the viscosity change of the composition and cured product upon heating will be appropriate.

[0051] Furthermore, from the viewpoint of viscosity, groups other than the phenyl group are preferably alkyl groups having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups. It is also possible to use alkyl groups in which some of the hydrogen atoms are substituted with halogen atoms. Methyl groups are particularly preferred as alkyl groups.

[0052] The amount of component (D) is 1 to 50 parts by mass, preferably 5 to 30 parts by mass, per 100 parts by mass of component (A).

[0053] If the amount of component (D) is below the lower limit, it becomes difficult to control the tackiness, and if it exceeds the upper limit, the tackiness becomes too strong, which may worsen the reworkability.

[0054] Component (D) may be used alone or in combination of two or more types.

[0055] Furthermore, it is preferable that the thermosoftening phenyl silicone gel layer contains the following components (E) and (F). (E) Organopolysiloxane having a hydrolyzable functional group or an alkoxysilane compound which is component (E-3) represented by the following formula (3): 1 to 100 parts by mass R 1 a R 2 b Si(OR 3 ) 4-a-b (3) (In the formula, R 1 R is an alkyl group having 6 to 15 carbon atoms, 2 R is an independent monovalent hydrocarbon group having 1 to 15 carbon atoms. 3 (where a is an integer between 1 and 6 carbon atoms, b is an integer between 0 and 2, and a+b is an integer between 1 and 3.) (F) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, and carbon: in an amount of 10 to 95% by mass of the total composition

[0056] The above components (E) and (F) are explained below.

[0057] [(E) Organopolysiloxane or alkoxysilane compounds having hydrolyzable functional groups] Component (E) is preferably one or more selected from components (E-1), (E-2), and (E-3).

[0058] Component (E-1) is an organopolysiloxane having a hydrolyzable functional group represented by the following formula (1). [ka] (In the formula, R 4 These are independently aromatic hydrocarbon groups having 6 to 10 carbon atoms, R 5 R is an alkyl group having 1 to 10 carbon atoms, independently.6 (where a is an alkyl group with 1 to 4 carbon atoms, a is 2 or 3, and n is an integer between 2 and 60.)

[0059] In the above equation (1), R 4 R is an independent monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms. 4 Specific examples include aryl groups such as phenyl, tolyl, xylyl, and mesityl groups, with the phenyl group being preferred from the viewpoint of ease of synthesis.

[0060] In the above equation (1), R 5 R is an alkyl group having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms. 5 Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, octyl, nonyl, and decyl groups, with methyl and ethyl groups being particularly preferred.

[0061] In the above equation (1), R 6 R has 1 to 4 carbon atoms, preferably a methyl group or an ethyl group. 6 Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, and tert-butyl groups. Among these, methyl and ethyl groups are particularly preferred from the viewpoint of the hydrolysis properties of the organopolysiloxane compounds of the present invention. In addition, in the above general formula (1), a is usually an integer of 2 or 3, and is preferably 3.

[0062] In formula (1) above, n is usually an integer between 2 ≤ n ≤ 60, more preferably 9 ≤ n ≤ 30, and even more preferably 12 ≤ n ≤ 18. Outside of this range, compatibility with the phenyl-modified silicone, which is components (A) and (B), is significantly reduced and therefore undesirable.

[0063] Component (E-2) is a hydrolyzable organopolysiloxane represented by the following formula (2). [ka] (In the formula, R 7 These are independently monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms, R 8 R is an alkyl group having 1 to 10 carbon atoms, independently. 9 (where b is an alkyl group having 1 to 4 carbon atoms, b is 2 or 3, p is an integer between 1 and 30, and q is an integer between 0 and 60, provided that 3 is equal to or equal to p + q is equal to or equal to 90.)

[0064] In equation (2) above, R 7 R is an independent monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms. 7 Specific examples include aryl groups such as phenyl, tolyl, xylyl, and mesityl groups, with the phenyl group being preferred.

[0065] In equation (2) above, R 8 R is an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms. 8 Examples of these groups include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, octyl, nonyl, and decyl groups, with the methyl group being preferred among them.

[0066] In equation (2) above, R 9 R is independently an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group. 9 Examples of these groups include methyl, ethyl, propyl, isopropyl, butyl, and tert-butyl groups. Among these, the methyl group is particularly preferred from the viewpoint of the hydrolysis properties of the organopolysiloxane compound of the present invention. In addition, in formula (2) above, b is 2 or 3, but from the viewpoint of ease of synthesis and economic efficiency, b is preferably 3.

[0067] In formula (2) above, p is usually an integer between 1 ≤ p ≤ 30, preferably 3 ≤ p ≤ 20, and more preferably 5 ≤ p ≤ 18. If p exceeds 30, the viscosity of the organopolysiloxane increases significantly, which is undesirable. Also, in general formula (1) above, q is usually an integer between 0 ≤ q ≤ 60, preferably 5 ≤ q ≤ 50, and more preferably 10 ≤ q ≤ 40. Outside this range, the compatibility with phenyl-modified silicone decreases, which is undesirable. Furthermore, p + q is between 3 ≤ p + q ≤ 90, and preferably 6 ≤ p + q ≤ 60. Outside this range, the handling of the composition becomes poor, which is undesirable.

[0068] Component (E-3) is an alkoxysilane compound represented by the following formula (3). R 1 a R 2 b Si(OR 3 ) 4-a-b (3) (In the formula, R 1 R is an alkyl group having 6 to 15 carbon atoms, 2 R is an independent monovalent hydrocarbon group having 1 to 15 carbon atoms. 3 (where a is an integer between 1 and 6 carbon atoms, b is an integer between 0 and 2, and a+b is an integer between 1 and 3.)

[0069] In the above general formula (3), R 1 Examples of alkyl groups represented by this R include hexyl, octyl, nonyl, decyl, dodecyl, and tetradecyl groups. 1 When the number of carbon atoms in the alkyl group represented by satisfies the range of 6 to 15, the wettability of component (A) is sufficiently improved, and handling becomes easier.

[0070] R 2Examples of monovalent hydrocarbon groups represented by include alkyl groups having 1 to 5 carbon atoms, preferably 1 to 3; aryl groups having 6 to 15 carbon atoms, preferably 6 to 12; and aralkyl groups having 7 to 15 carbon atoms, preferably 7 to 12. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, and neopentyl groups. Examples of aryl groups include phenyl, tolyl, xylyl, naphthyl, and biphenylyl groups. Examples of aralkyl groups include benzyl, phenylethyl, phenylpropyl, and methylbenzyl groups. Among these, methyl, ethyl, propyl, and phenyl groups are preferred.

[0071] R 3 Examples include methyl groups, ethyl groups, propyl groups, butyl groups, and hexyl groups.

[0072] The amount of component (E) is preferably 1 to 100 parts by mass, and more preferably 1 to 50 parts by mass. If the amount is 1 part by mass or more, the surface treatment of the thermal conductive filler is sufficient, and there are no problems with the blending of the thermal conductive filler into the silicone. If the amount is 100 parts by mass or less, the cured product does not become too soft, and the thermo-softening silicone gel layer does not break when the thermal conductive composite silicone rubber sheet is peeled off the release film.

[0073] [(F) Thermally conductive filler] Component (F) is one or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, and carbon. Examples include aluminum, silver, alumina, zinc oxide, magnesium oxide, aluminum oxide, silicon dioxide, cerium oxide, iron oxide, aluminum hydroxide, cerium hydroxide, aluminum nitride, boron nitride, and carbon fibers. These can be used individually or in appropriate combinations of two or more.

[0074] The amount of component (F) is 10 to 95% by mass of the total composition, preferably 20 to 93% by mass, more preferably 30 to 92% by mass, and even more preferably 50 to 90% by mass. If the amount is 95% by mass or less, there will be no problems with the viscosity or processability of the composition. Furthermore, if the amount is 10% by mass or more, thermal conductivity can be obtained.

[0075] [Thermal resistance] The thermal resistance of the softening silicone gel layer of the thermally conductive composite silicone sheet of the present invention is 0.2 cm 2 It is preferable that it be 0.1 cm or less, and more preferably 0.1 cm 2 • Thermal resistance of 0.2 cm² or less (K / W or less) 2 If the wattage is below kW, the increase in thermal resistance when tackiness is added to the thermally conductive composite silicone sheet can be minimized.

[0076] The thermal resistance was measured using a TIM-Tester (manufactured by Analysistech) compliant with ASTM D 5470, under 20% compression and at a measurement temperature of 50°C.

[0077] [Tackiness] The thermally conductive composite silicone sheet of the present invention preferably has adhesive properties that allow it to be fixed to the vertical surface of an aluminum plate for at least one hour. For example, it is preferable that the thermally conductive composite silicone sheet has sufficient adhesive properties to prevent any displacement when the thermo-softening phenyl silicone gel layer of the thermally conductive composite silicone sheet is pressed onto the aluminum plate with a rubber roller, the aluminum plate is immediately placed vertically, and left for one hour. [Examples]

[0078] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these.

[0079] The kinematic viscosity of organopolysiloxane is the value measured at 25°C using an Ostwald viscometer.

[0080] Furthermore, the average degree of polymerization can be determined as the number-average degree of polymerization in polystyrene terms using gel permeation chromatography (GPC).

[0081] [Measurement conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.6mL / min Detector: Differential refractive index detector (RI) Column: TSK Guardcolumn SuperH-H TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) TSKgel SuperH2000(6.0mmI.D.×15cm×1) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 50 μL (THF solution with a concentration of 2.0% by mass)

[0082] [Thermally conductive silicone rubber sheet] <Carbon fiber-containing organopolysiloxane composition 1> A carbon fiber-containing organopolysiloxane composition 1 was obtained by mixing 38.2% by mass of an addition-reaction type organopolysiloxane composition, 22.6% by mass of carbon fibers (average fiber length 50 μm, average fiber diameter 10 μm, aspect ratio 5), 22.6% by mass of carbon fibers (average fiber length 250 μm, average fiber diameter 10 μm, aspect ratio 25), and 16.6% by mass of toluene.

[0083] The components of the above addition-type organopolysiloxane composition consist of the following components (1-1) to (1-3).

[0084] (1-1) Ingredients Organopolysiloxane represented by the following formula: 97.1% by mass [ka]

[0085] In the above formula, n is the kinematic viscosity at 25°C, calculated as 30,000 mm². 2 This is the number represented by / s.

[0086] (1-2) Components Organohydrogenpolysiloxane represented by the following formula: 2.2% by mass [ka] In the above formula, o = 27 and p = 3, which are the average degrees of polymerization, respectively.

[0087] (1-3) Components 5% 2-ethylhexanol chloroplatinate solution: 0.7% by mass

[0088] <Carbon fiber-containing organopolysiloxane composition 2> Carbon fiber-containing organopolysiloxane composition 2 was obtained by mixing 23.5% by mass of an addition-reaction type organopolysiloxane composition similar to carbon fiber-containing organopolysiloxane composition 1, 24.6% by mass of carbon fibers (average fiber length 50 μm, average fiber diameter 10 μm, aspect ratio 5), 24.6% by mass of carbon fibers (average fiber length 250 μm, average fiber diameter 10 μm, aspect ratio 25), and 27.3% by mass of toluene.

[0089] <Thermal conductive silicone rubber sheet 1> We prepared a mold for the filling process with a width of 1.5 mm, a length of 50.0 mm, a depth of 2.5 mm, and a semicircular groove at the bottom. We also prepared a lower mold for the molding process with internal dimensions of 33.0 mm (X-axis), 52.0 mm (Y-axis), and 50.0 mm (Z-axis), and an upper mold for the molding process with dimensions of 32.9 mm (width), 51.9 mm (length), and 40.0 mm (height).

[0090] The carbon fiber-containing organopolysiloxane composition 1 was filled into the mold used in the above filling process so that it overflowed from the grooves, and the overflowed portion was scraped off with a squeegee.

[0091] A mold used in the filling process, filled with the above-mentioned carbon fiber-containing organopolysiloxane composition 1, was vibrated for 30 minutes in a Sharp UT-106 tabletop ultrasonic cleaner at a water temperature of 25°C, a frequency of 37KHz, and 100% output, and then dried at 80°C for 2 minutes to obtain the carbon fiber-containing string-like resin composition 1. Furthermore, the above-mentioned carbon fiber-containing string-like resin composition 1 was filled into the lower mold used in the molding process in the Y-axis direction, with 21 rows in the X-axis direction and 40 rows in the Z-axis direction. The upper mold used in the molding process was then heated at 120°C for 30 minutes while being pressurized at 1.0 MPa in the Z-axis direction using a hydraulic press to obtain a carbon fiber-containing silicone molded body 1. The carbon fiber-containing silicone molded body was sliced ​​parallel to the XZ plane using an ultrasonic cutter to obtain a thermally conductive silicone rubber sheet 1. The arithmetic mean roughness of the sheet surface of the obtained thermally conductive silicone rubber sheet 1 was 12.3 μm, and the Asker C hardness was 23.

[0092] The arithmetic mean roughness was measured using a Keyence VR-6000 one-shot 3D shape measuring machine with a lens magnification of 12x and an evaluation length of 27mm.

[0093] <Thermal conductive silicone rubber sheet 2> The carbon fiber-containing organopolysiloxane composition 1 was replaced with carbon fiber-containing organopolysiloxane composition 2, and a thermally conductive silicone rubber sheet 2 was obtained using the same manufacturing method as for thermally conductive silicone rubber sheet 1. The arithmetic mean roughness of the sheet surface of the obtained thermally conductive silicone rubber sheet 2 was 8.6 μm, and the Asker C hardness was 42.

[0094] [Thermo-softening silicone gel layer] Preparation of thermosoftening silicone gel compositions The components (A) to (F) used in the following examples and comparative examples are shown below. In the formulas, Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group.

[0095] (A) component (A-1): Expressed by the following formula, when the kinematic viscosity is 2,000 mm 2 ·s -1Phenyl-modified organopolysiloxane with a phenyl denaturation rate of 67% [ka] (A-2): Expressed by the following formula, when the kinematic viscosity is 700 mm 2 ·s -1 Phenyl-modified organopolysiloxane with a phenyl denaturation rate of 23% [ka] (A-3): Silicone resin represented by the following formula D 25 T Φ 55 D Vi 20 However, D is Me2SiO 2 / 2 , T Φ PhSiO 3 / 2 , D Vi is ViMeSiO 2 / 2 That is the case.

[0096] (B) Component (B-1): The kinematic viscosity is 4 mm², as expressed by the following formula. 2 ·s -1 Phenyl-modified organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain. [ka] (B-2): The kinematic viscosity is 20 mm², as expressed by the following formula. 2 ·s -1 Phenyl-modified organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain and in the side chain. [ka] (B-3): The kinematic viscosity is 20 mm², as expressed by the following formula. 2 ·s -1 Phenyl-modified organohydrogenpolysiloxane having a hydrosilyl group in its side chain [ka]

[0097] (C) Component 5% 2-ethylhexanol chloroplatinate solution

[0098] (D) Component Phenyl-modified organopolysiloxane, represented by the following formula [ka]

[0099] (E) Component (E-1): Hydrolyzable organopolysiloxane represented by the following formula [ka] (E-2): Hydrolyzable organopolysiloxane represented by the following formula [ka]

[0100] (F) component The particle size of the thermally conductive filler was measured using a particle size distribution analyzer, MT3000II (manufactured by Microtrac-Bell Co., Ltd.). (F-1): Spherical aluminum powder (average particle size: 1 μm) (F-2): Amorphous zinc oxide powder (average particle size: 1 μm)

[0101] [Manufacturing method] Thermosoftening phenyl silicone gel composition The compositions of the examples and comparative examples were obtained by mixing components (A) to (F) as follows. Components (A), (B), (D), and (E) were weighed out and placed in a metal kettle of a planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.) in the composition ratio (parts by mass) shown in Table 1. The mixture was stirred at room temperature and 30 rpm for 1 hour, then component (F) was added and stirred at room temperature and 30 rpm for 30 minutes. Finally, component (C) was added and stirred at room temperature and 30 rpm for 20 minutes.

[0102] Thermosoftening phenyl silicone gel cured product The obtained thermosoftening phenylsilicone gel composition was diluted with toluene to a solvent concentration of 10% by mass and applied to a 50 μm thick fluorine-treated release PET (product name FL1-01: manufactured by Takaline Corporation). The mixture was cured in a 100°C oven for 10 minutes to obtain a thermosoftening phenylsilicone gel cured product.

[0103] Table 1 shows the composition of the prepared thermosoftening silicone gel cured product.

[0104] [Table 1]

[0105] Thermally conductive composite silicone sheet A thermally conductive composite silicone sheet was obtained by pressing a heat-softening phenyl silicone gel cured material onto one side of a thermally conductive silicone rubber sheet 1 or 2 at 90°C for 30 seconds at 0.1 MPa.

[0106] The composition, physical properties, and evaluation results of the fabricated thermally conductive composite silicone sheets are shown in Table 2 for Examples 1 to 8 and in Table 3 for Comparative Examples 1 to 4.

[0107] [Evaluation Method] [Thermal conductive silicone rubber sheet thickness] Measurements were taken using a Mitutoyo thickness gauge.

[0108] [Thickness of thermosoftening phenyl silicone gel] The measurement was performed using a Mitutoyo micrometer.

[0109] [Complexity] A heat-softening phenyl silicone gel cured material was pressed onto one side of a heat-conductive silicone rubber sheet at 90°C for 30 seconds at 0.1 MPa to form a composite. After this, samples were marked with ○ if the heat-softening phenyl silicone gel cured material could be peeled off the fluorine-treated peelable PET without any residue, △ if some residue remained, and × if all residue remained.

[0110] [Tackiness] A 20mm x 20mm heat-conductive composite silicone sheet with a heat-softening phenyl silicone gel layer was pressed onto an aluminum plate using a 500g rubber roller with two passes. Immediately afterward, the aluminum plate was placed vertically and left for 1 hour. Sheets that did not shift at all were marked with a circle (○), and those that detached or shifted were marked with a cross (×).

[0111] [Thermal resistance measurement] The thermal resistance of the thermally conductive silicone rubber sheet alone and the resulting thermally conductive composite silicone sheet was measured using a TIM-Tester (Analysistech) compliant with ASTM D 5470, under conditions of 20% compression and a measurement temperature of 50°C. The thermal resistance of the thermosoftening phenyl silicone gel layer was calculated by subtracting the thermal resistance of the thermally conductive silicone rubber sheet alone from the thermal resistance of the thermally conductive composite silicone sheet.

[0112] [Table 2]

[0113] [Table 3]

[0114] In Example 1, the thermosoftening phenyl silicone gel was able to be compounded, and its adhesive properties were good. When the thickness of the thermosoftening phenyl silicone gel was increased, as in Example 2, the compounding properties and adhesive properties were maintained, but the thermal resistance increased.

[0115] In Example 3, even when component (B) of the thermosoftening phenyl silicone gel composition had hydrosilyl groups at both ends of the molecular chain and on the side chain, the thermosoftening properties were maintained, and the results regarding composite properties and tackiness were equivalent to those of Example 2.

[0116] In Example 4, the addition of components (E) and (F) imparted thermal conductivity to the thermosoftening phenyl silicone gel, resulting in a lower thermal resistance than in Example 1. There was no decrease in composite properties or tackiness.

[0117] In Example 5, the type of thermally conductive silicone rubber sheet was changed from that in Example 4, but the composite properties, tackiness, and thermal resistance of the thermosoftening phenyl silicone gel were equivalent to those of Example 4.

[0118] Examples 6 and 7 differed from Example 5 in that the thickness of the thermally conductive sheet was changed, but the thermal resistance of the composite, adhesive, and thermosoftening phenyl silicone gel was equivalent to that of Example 5.

[0119] Example 8 involved modifying component (E) of the thermosoftening phenylsilicone gel composition of Example 5, but the composite properties, tackiness, and thermal resistance of the thermosoftening phenylsilicone gel were equivalent to those of Example 5.

[0120] In Comparative Example 1, the (B) component of the thermosoftening phenylsilicone gel composition lacked hydroxyl groups at both ends of the molecular chain, resulting in poor thermosoftening properties, and therefore, compounding was not possible.

[0121] In Comparative Example 2, the phenyl modification rate of component (A) of the thermosoftening phenyl silicone gel composition was low at 23%, resulting in less interaction with the benzene rings constituting the carbon fibers, and therefore, compounding was not possible.

[0122] In Comparative Example 3, components (B) and (C) of the thermosoftening phenyl silicone gel composition were not used, and instead silicone resin was used, so compounding was not possible.

[0123] In Comparative Example 4, since component (D) was not included in the thermosoftening phenyl silicone gel composition of Example 5, compounding was possible, but the adhesiveness was insufficient, resulting in a negative rating for adhesiveness.

[0124] This specification includes the following embodiments. [1]: A thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, A thermosoftening phenyl silicone gel layer containing the following components (A) to (D) is disposed on one or both sides of the thermally conductive silicone rubber sheet. A thermally conductive composite silicone sheet characterized by having the following properties. (A) A phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a phenyl modification rate of 50% or more: 100 parts by mass (B) An organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain: an amount such that the molar number of hydrosilyl groups in component (B) is 0.1 to 3 moles with respect to 1 mole of the alkenyl group in component (A) (C) A platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms with respect to the mass of component (A) (D) A non-reactive phenyl-modified organopolysiloxane: 1 to 50 parts by mass [2]: The thermally conductive composite silicone sheet according to [1], wherein the thickness of the thermally softening phenyl silicone gel layer is 15 μm to 100 μm. [3]: The thermally conductive composite silicone sheet according to [1] or [2], wherein the thermally softening phenyl silicone gel layer is a thermally softening phenyl silicone gel layer containing the following components (E) and (F). (E) An organopolysiloxane having a hydrolyzable functional group or an alkoxysilane compound which is a component (E-3) represented by the following formula (3): 1 to 100 parts by mass R 1 a R 2 b Si(OR 3 ) 4-a-b (3) (In the formula, R 1 is independently an alkyl group having 6 to carbon atoms, R 2 is independently a monovalent hydrocarbon group having 1 to carbon atoms, R 3 is independently an alkyl group having 1 to carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, provided that a + b is an integer of 1 to 3.) (F) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, and carbon: an amount of 10 to 95% by mass based on the whole composition [4]: The organopolysiloxane having a hydrolyzable functional group in component (E) is a component (E-1) represented by the following formula (1) It should be noted that there are some incomplete carbon atom numbers in the original text which are represented by " to " in the above translation. You may need to check and correct the original text for a more accurate translation. [Chemical formula] (In the formula, R 4 is independently an aromatic hydrocarbon group having 6 to 10 carbon atoms, R 5 is independently an alkyl group having 1 to 10 carbon atoms, R 6 is an alkyl group having 1 to 4 carbon atoms. a is 2 or 3, and n is an integer of 2 ≤ n ≤ 60.) and the (E-2) component represented by the following formula (2) [Chemical formula] (In the formula, R 7 is independently a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, R 8 is independently an alkyl group having 1 to 10 carbon atoms, R 9 is an alkyl group having 1 to 4 carbon atoms. b is 2 or 3, p is an integer of 1 ≤ p ≤ 30, q is an integer of 0 ≤ q ≤ 60, provided that 3 ≤ p + q ≤ 90 is satisfied.) The thermally conductive composite silicone sheet according to [3], characterized in that it is selected from [5]: The thermally conductive composite silicone sheet according to any one of [1] to [4], characterized in that the thermally conductive composite silicone sheet has adhesiveness capable of being fixed on the vertical surface of an AL plate for 1 hour or more [6]: Using a TIM-Tester conforming to ASTM D 5470, the thermal resistance of the thermally softening silicone gel layer measured at 20% compression and a measurement temperature of 50°C is 0.2 cm 2 ·K / W or less. The thermally conductive composite silicone sheet according to any one of [1] to [5], characterized in that

[0125] [[ID=

Claims

1. A thermally conductive silicone rubber sheet in which carbon fibers are oriented in the thickness direction, A thermosoftening phenyl silicone gel layer containing the following components (A) to (D) is disposed on one or both sides of the thermally conductive silicone rubber sheet. A thermally conductive composite silicone sheet characterized by having the following properties. (A) Phenyl-modified organopolysiloxane having two or more alkenyl groups in one molecule and a phenyl modification rate of 50% or more: 100 parts by mass (B) Organohydrogenpolysiloxane having hydrosilyl groups at both ends of the molecular chain: an amount such that the number of moles of hydrosilyl groups in component (B) is 0.1 to 3 moles per mole of alkenyl groups in component (A) above. (C) Platinum group metal catalyst: 0.01 to 1,000 ppm on a mass basis converted to platinum group metal atoms relative to the mass of component (A) above. (D) Non-reactive phenyl-modified organopolysiloxane: 1 to 50 parts by mass

2. The thermally conductive composite silicone sheet according to claim 1, characterized in that the thickness of the heat-softening phenyl silicone gel layer is 15 μm to 100 μm.

3. The thermally conductive composite silicone sheet according to claim 1, characterized in that the thermally softening phenyl silicone gel layer is a thermally softening phenyl silicone gel layer containing the following components (E) and (F). (E) Organopolysiloxane having a hydrolyzable functional group or an alkoxysilane compound which is component (E-3) represented by the following formula (3): 1 to 100 parts by mass R １ ａ R ２ ｂ Si(OR ３ ) ４－ａ－ｂ (3) (wherein, R １ is independently an alkyl group having 6 to 15 carbon atoms, R ２ is independently a monovalent hydrocarbon group having 1 to 15 carbon atoms, R ３ is independently an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, provided that a + b is an integer of 1 to 3.) (F) One or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, and carbon: in an amount of 10 to 95% by mass of the entire composition

4. The organopolysiloxane having a hydrolyzable functional group of component (E) above is represented by the following formula (1) as component (E-1). 【Chemistry 1】 (In the formula, R ４ R is an aromatic hydrocarbon group having 6 to 10 carbon atoms, independently. ５ R is an alkyl group having 1 to 10 carbon atoms, independently. ６ (where a is an alkyl group having 1 to 4 carbon atoms, a is 2 or 3, and n is an integer between 2 and 60.) And the (E-2) component represented by the following equation (2) 【Chemistry 2】 (In the formula, R ７ R is an independent monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms. ８ R is an alkyl group having 1 to 10 carbon atoms, independently. ９ b is an alkyl group having 1 to 4 carbon atoms. b is 2 or 3, p is an integer between 1 and 30, and q is an integer between 0 and 60, provided that 3 is within the range of p + q ≤ 90. The thermally conductive composite silicone sheet according to claim 3, characterized in that it is selected from among the following.

5. The thermally conductive composite silicone sheet according to claim 1, characterized in that the thermally conductive composite silicone sheet has adhesive properties that allow it to be fixed to the vertical surface of an AL plate for more than one hour.

6. The thermal resistance of the thermosoftening silicone gel layer was measured at 20% compression and a measurement temperature of 50°C using a TIM-Tester compliant with ASTM D 5470, and the result was 0.2 cm². ２ The thermally conductive composite silicone sheet according to claim 1, characterized in that it is less than or equal to K / W.

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