Thermally conductive silicone composition and method for producing same

Abstract

Provided is a thermally conductive silicone composition which has high thermal conductivity, is exceptional in workability and slippage resistance, and is produced under mild conditions that do not require heating conditions at a temperature higher than 50°C during the production process.　The thermally conductive silicone composition contains a reaction product of components (A) and (B), and component (C). (A) An organopolysiloxane that has an organic group having an acid anhydride group bonded to a silicon atom, and has no alkoxy groups bonded to silicon atoms. (B) An organopolysiloxane that has an amino group. (C) A thermally conductive filler.

Description

Thermally conductive silicone composition and method for producing the same

[0001] The present invention relates to a thermally conductive silicone composition having high thermal conductivity and excellent workability and shear resistance, and a method for producing the same.

[0002] Many heat-generating electronic components mounted on printed circuit boards, such as CPUs, widely utilize heat sinks and other heat dissipation devices to prevent damage and performance degradation due to temperature increases during use. Generally, thermally conductive materials are used between the heat-generating electronic component and the heat dissipation device to efficiently transfer the heat generated by the component. However, with the increasing performance of electronic components, the amount of heat generated tends to increase, creating a demand for the development of materials and components with even greater thermal conductivity than conventional ones.

[0003] Generally, electrical and electronic components generate heat during use, so heat dissipation measures are necessary to ensure proper operation of these components, and various thermally conductive materials have been proposed for heat dissipation. These thermally conductive materials can be broadly classified into two forms: 1) sheet-type heat dissipation materials that are easy to handle, and 2) paste-type heat dissipation materials. Sheet-type heat dissipation materials can be easily mounted on heat-generating electronic components or heat sinks, but because air gaps are created at the interface with the heat-generating electronic components or heat sinks, the interfacial thermal resistance increases, resulting in insufficient heat conduction performance. On the other hand, paste-type heat dissipation materials, because their properties are close to those of a liquid, have less impact on the surface irregularities of heat-generating electronic components or heat sinks, and can adhere closely to both, thus reducing interfacial thermal resistance. However, when mass-producing using screen printing, stencil printing, etc., it is preferable for the viscosity of the paste-type heat dissipation material to be low, but in that case, the paste-type heat dissipation material may shift away from the component (pump-out phenomenon) due to thermal shock of the component, resulting in insufficient heat dissipation and, as a result, the component may malfunction. The following silicone compositions have been proposed as prior art, and thermally conductive silicone compositions that provide sufficient performance and excellent shear resistance are known (Patent Documents 1 to 5).

[0004] To achieve shear resistance, silicone gel is used as a paste-like heat dissipation material. This gel is manufactured by a hydrosilylation reaction between alkenyl groups bonded to silicon atoms and hydrogen atoms bonded to silicon atoms under high-temperature heating conditions. Furthermore, considering the current environmental impact, if an addition reaction can be used instead of gelation (hydrosilylation) during the manufacturing process, it will be possible to provide a new, environmentally friendly material: a thermally conductive silicone composition that can be manufactured under mild conditions without requiring high-temperature heating.

[0005] Japanese Patent Publication No. 2006-143978, Japanese Patent Publication No. 2010-100665, Japanese Patent Publication No. 2010-126568, Japanese Patent Publication No. 2022-108648, Japanese Patent Publication No. 2023-026788

[0006] Therefore, the present invention aims to provide a thermally conductive silicone composition that has high thermal conductivity, excellent workability and shear resistance, and can be manufactured under mild conditions that do not require heating conditions at temperatures higher than 50°C during the manufacturing process.

[0007] As a result of diligent research to achieve the above objective, the present inventors have discovered that by mixing an organopolysiloxane having an acid anhydride group with an organic group having an amino group and using the amide bond obtained by the addition reaction between the acid anhydride group and the amino group as a crosslinking portion of the silicone gel, it is possible to obtain a thermally conductive silicone composition with high thermal conductivity, excellent workability and shear resistance, without requiring heating conditions at temperatures higher than 50°C, and thus the present invention has been made. That is, the present invention provides the following thermally conductive silicone composition and a method for producing the same.

[0008] [1] A thermally conductive silicone composition comprising the reaction product of component (A) and component (B) below, and component (C). (A) An organopolysiloxane having an organic group having an acid anhydride group bonded to a silicon atom, and not having an alkoxy group bonded to a silicon atom. (B) An organopolysiloxane having an amino group. (C) A thermally conductive filler. [2] The thermally conductive silicone composition according to [1], further comprising an alkoxy group-containing organopolysiloxane represented by the following general formula (1) as component (D). (In formula (1), R 1 R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, 2 (1) is an alkyl group having 1 to 6 carbon atoms, and P is a number from 5 to 120.) [3] The amount of component (B) is such that the amount of amino groups in the organopolysiloxane molecule of component (B) is 0.1 to 3.0 moles per mole of acid anhydride groups bonded to silicon atoms in the organopolysiloxane molecule of component (A), and the amount of component (C) is such that it is 30 to 95% by volume in the thermally conductive silicone composition, as described in [1] or [2]. [4] The amount of component (A) is an organopolysiloxane of the following average composition formula (2), as described in any of [1] to [3]. R''R2SiO-(R2SiO) n -SiR2R'' (2) (In formula (2), R is independently a hydrocarbyl group having 1 to 8 carbon atoms, R'' is independently an organic group having an acid anhydride group, and n is a number from 0 to 200.) [5] The thermally conductive silicone composition according to [4], wherein the organic group having an acid anhydride group in R'' of formula (2) is the group shown in the following formula (3). (In formula (3), X is a hydrogen atom or a hydrocarbyl group having 1 to 8 carbon atoms, and a is a number from 1 to 6.) [6] The thermally conductive silicone composition according to [5], wherein X in formula (3) is independently selected from a hydrogen atom and an aromatic group, and a is 2, or X is a hydrogen atom and a is 3. [7] A method for producing the thermally conductive silicone composition according to any one of [1] to [6], comprising the following steps (1) to (3): (1) a step of uniformly mixing the components (A) to (C) to obtain a paste-like composition; (2) a step of mixing the paste-like composition at room temperature to obtain a paste-like composition in which a crosslinked structure has been formed; and (3) a step of shear mixing the paste-like composition in which the crosslinked structure has been formed at a temperature of 50°C or lower.

[0009] The thermally conductive silicone composition of the present invention not only has high thermal conductivity, excellent workability and shear resistance, but is also manufactured under mild conditions that do not require high-temperature heating conditions (heating at temperatures higher than 50°C) during the manufacturing process, and the manufacturing process is environmentally friendly.

[0010] The present invention will be described in detail below, but is not limited to these descriptions. First, the components contained in the thermally conductive silicone composition will be described.

[0011] <Thermally conductive silicone composition> Component (A) Component (A) is an organopolysiloxane having an organic group having an acid anhydride group bonded to a silicon atom, and no alkoxy group bonded to a silicon atom, and contains an average of more than one of these organic groups having an acid anhydride group bonded to a silicon atom per molecule, preferably 0.01 to 5 mol%, more preferably 0.012 to 3 mol%, of the total organic groups. More preferably, it is contained in an amount such that the anhydride equivalent is 500 g / mol to 7500 g / mol. These organic groups having an acid anhydride group bonded to a silicon atom may be present at either the molecular chain end or the non-molecular chain end, or both, but it is preferable that they be present only at both molecular chain ends for better flexibility.

[0012] The molecular structure of the organopolysiloxane of component (A) is not particularly limited, and examples thereof include linear, branched, and the like.

[0013] The kinematic viscosity at 25°C of the organopolysiloxane of component (A) is not particularly limited, but is preferably in the range of 10 to 1,000,000 mm 2 / s, and since the stability of the composition is good and the mixing with components (B) and (C) described later becomes easy, the range of 50 to 100,000 mm 2 / s is more preferable. The kinematic viscosity is the value measured by an Ostwald viscometer at 25°C.

[0014] Component (A) may be an organopolysiloxane represented by the following average composition formula (2). R’’R2SiO−(R2SiO) n −SiR2R’’ (2)

[0015] In formula (2), n has an average value within the range of 0 to 200, R is independently a hydrocarbyl group, and R’’ is independently selected from the group consisting of a hydrocarbyl group having 1 to 8 carbon atoms, a silyl hydride (hydrogen atom), and an organic group having an acid anhydride group, and at least one of R’’ is an organic group having an acid anhydride group. Preferably, R’’ is an organic group having an acid anhydride group. The acid anhydride group may be succinic anhydride having the chemical structure (3). In formula (3), X is independently selected from a hydrogen atom and a hydrocarbyl group having from one to eight carbon atoms, and a independently has a value of 1 or more, 2 or more, 3 or more, 4 or more, or even 5 or more, and at the same time, 6 or less, 5 or less, 4 or less, 3 or less, or even 2 or less. The hydrocarbyl group having 1 to 8 carbon atoms may be any one or two or more aromatic groups such as residues from aromatic radical initiators such as benzoyl or residues from aromatic solvents such as xylyl or tolyl.

[0016] The organopolysiloxane of component (A) can have the chemical structure (3), and in the formula, when a is 2, X is independently selected from a hydrogen atom and an aromatic group, and when a is 3, X is a hydrogen atom.

[0017] The hydrocarbyl group bonded to the silicon atom represented by R in the formula (2) is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms. Specific examples of the monovalent hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group; alkenyl groups such as vinyl group, allyl group; aryl groups such as phenyl group, tolyl group; aralkyl groups such as 2-phenylethyl group, 2-phenylpropyl group; and 3,3,3-trifluoropropyl group, 3-(perfluorobutyl)ethyl group, 2-(perfluorooctyl)ethyl group, p-chlorophenyl group, etc., in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as chlorine atom, fluorine atom. Among these, from the viewpoints of ease of synthesis and economy, preferably, they are methyl group and phenyl group, and in particular, 80 mol% or more, especially 90 mol% or more of all organic groups other than the organic group having an acid anhydride group bonded to the silicon atom is methyl group.

[0018] The organic group having an acid anhydride group preferably has 20 or less carbon atoms, more preferably 10 or less carbon atoms. As specific examples thereof, the organic group having an acid anhydride group can be introduced by a hydrosilylation reaction. As an example of the synthesis of a silyl hydride reaction, a linear-chain both-end SiH organopolysiloxane can be reacted with allyl succinic anhydride in the presence of a hydrosilylation catalyst (such as a platinum catalyst). (In the formula, R is independently a hydrocarbyl group having 1 to 8 carbon atoms, and m is a number from 0 to 200.)

[0019] Here, depending on the molar ratio of the raw materials, the reaction product may contain any of the following compounds. (aa) Unreacted both-end SiH organopolysiloxane: H—R2SiO—(R2SiO) m —SiR2—H (bb) Mono-end anhydride group organopolysiloxane: H—R2SiO—(R2SiO) m —SiR2—A' (cc) Both-end anhydride group organopolysiloxane: A'—R2SiO—(R2SiO) m-SiR2-A' In the above equations (bb) and (cc), "A'" is as shown in equation (5) below. (In equation (5), X is a hydrogen atom (H).)

[0020] The above reaction product typically contains an organopolysiloxane mainly composed of (cc) terminal acid anhydride groups. The reaction product can be used as the organopolysiloxane of component (A) without further purification, provided that the average number of acid anhydride groups per molecule of organopolysiloxane is within the required range.

[0021] A specific example of the organopolysiloxane of component (A) is the one shown in formula (6) below.

[0022] (In formula (6), Me represents a methyl group, and n is a number between 0 and 200 (average value).)

[0023] The content of component (A) in the thermally conductive silicone composition of the present invention is 0.001 to 5% by mass, preferably 0.005 to 1% by mass, and more preferably 0.010 to 0.5% by mass. The organopolysiloxane of component (A) may be used alone or in combination of two or more types.

[0024] Component (B) Component (B) is an organopolysiloxane having an amino group attached to an organic group bonded to a silicon atom in the molecule, preferably containing at least 2, more preferably 2 to 30 amino groups in one molecule. The amine equivalent is preferably 5,000 g / mol to 500 g / mol, and more preferably 4,000 g / mol to 1,000 g / mol. The amino groups attached to the organic group bonded to the silicon atom may be present in either the molecular chain terminals or the molecular chain side chains, or both, within the organopolysiloxane molecule.

[0025] The molecular structure of the organopolysiloxane having an amino group in component (B) is not particularly limited and can be linear, branched, etc.

[0026] The kinematic viscosity of the organopolysiloxane having an amino group in component (B) at 25°C is not particularly limited, but is between 10 and 3000 mm². 2 A range of / s is preferred, between 100 and 2500 mm. 2 A range of / s is more preferable. The kinematic viscosity was measured using an Ostwald viscometer at 25°C.

[0027] Organic groups bonded to silicon atoms other than the aforementioned organic groups having an amino group are unsubstituted or substituted monovalent hydrocarbon groups having 1 to 20, preferably 1 to 6, carbon atoms. Specific examples of these monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; alkenyl groups such as vinyl and allyl groups; aryl groups such as phenyl and tolyl groups; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl groups; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as chlorine and fluorine atoms, such as 3,3,3-trifluoropropyl, 3-(perfluorobutyl)ethyl, 2-(perfluoroctyl)ethyl, and p-chlorophenyl groups. Among these, from the viewpoint of ease of synthesis and economic considerations, it is preferable that 80 mol% or more, and particularly 90 mol% or more, of the total organic groups other than those bonded to the silicon atom are methyl groups.

[0028] A specific example of the organopolysiloxane of component (B) is the one shown in formula (7) below. (In formula (7), R 3 R is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms. 4 R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and may be the same or different groups. 3 and R 4 Methyl, ethyl, and phenyl groups are particularly preferred. m is a number from 2 to 200, n is a number of 10 or more, and b is a number from 0 to 3.

[0029] The amount of component (B) is such that, for every mole of acid anhydride groups bonded to silicon atoms in the organopolysiloxane molecule of component (A), the amount of amino groups in the organopolysiloxane molecule of component (B) is preferably 0.1 to 3.0 moles, more preferably 0.2 to 1.5 moles, and particularly preferably 0.3 to 1.2 moles. The organopolysiloxane having amino groups of component (B) may be used alone or in combination of two or more types.

[0030] (C) Thermally conductive filler The thermally conductive filler of component (C) is a component that imparts thermal conductivity to the composition. This thermally conductive filler is not particularly limited, but one with good thermal conductivity is preferred. Specific examples include aluminum powder, zinc oxide powder, alumina powder, boron nitride powder, aluminum nitride powder, aluminum hydroxide powder, magnesium oxide powder, silicon nitride powder, copper powder, silver powder, diamond powder, nickel powder, zinc powder, stainless steel powder, carbon powder, and liquid metal.

[0031] Component (C) is not particularly limited and may be, for example, spherical particles or a mixture of particles of various shapes that are not particularly defined. Furthermore, the average particle size of the thermally conductive filler is not particularly limited, but is preferably 0.1 to 200 μm, more preferably 1 to 100 μm, as it is particularly excellent in viscosity and extensibility and yields a uniform composition. Here, the average particle size of the powder is the cumulative average diameter D in the volume-based particle size distribution obtained by laser diffraction scattering method. 50 This is the median diameter and is a value measured using a Microtrac MT3300EX from Microtrac-Bell Corporation.

[0032] The amount of component (C) is preferably 30 to 95% by volume, more preferably 35 to 85% by volume, in the thermally conductive silicone composition. Meeting this range results in excellent thermal conductivity of the composition. The thermally conductive filler of component (C) may be used alone or in combination of two or more types.

[0033] Other Components In addition to the components (A) to (C) described above, the following other components may be added as needed. These other components may be used individually or in combination of two or more. When adding components other than the components (A) to (C) described above and the components (D) and (E) shown below, there are no particular restrictions on the amount added, depending on the purpose, but usually it is 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the total of components (A) and (B).

[0034] <Wettability Enhancers> Wettability enhancers are components that improve the wettability of component (C) to components (A) and (B), and by improving wettability, the thermal conductivity of the composition is also improved. Specific examples include alkoxysilanes and alkoxy group-containing organopolysiloxanes represented by the following general formula (1) (component (D)) (hydrolyzable organopolysiloxanes with trifunctional molecular chain ends). (In formula (1), R 1 R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, 2 (Each is an alkyl group having 1 to 6 carbon atoms, and P is a number between 5 and 120.)

[0035] In the above formula (1), R 1 The unsubstituted or substituted monovalent hydrocarbon groups represented by have 1 to 20 carbon atoms, preferably 1 to 6. Specific examples include alkyl groups such as methyl, ethyl, propyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups; cyclohexyl groups such as cyclopentyl and cyclohexyl groups; alkenyl groups such as vinyl and allyl groups; aryl groups such as phenyl and tolyl groups; aralkyl groups such as 2-phenylethyl and 2-methyl-2-phenylethyl groups; and halogenated hydrocarbon groups such as 3,3,3-trifluoropropyl, 2-(perfluorobutyl)ethyl, 2-(perfluorooctyl)ethyl, and p-chlorophenyl groups, in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as chlorine and fluorine atoms, with methyl and vinyl groups being preferred.

[0036] In the above formula (1), R 2 The alkyl group represented by has 1 to 6 carbon atoms, preferably 1 to 2. Specific examples include methyl, ethyl, and propyl groups, with methyl and ethyl groups being preferred.

[0037] P is a number between 5 and 120, preferably between 10 and 90, and more preferably between 15 and 80.

[0038] Examples of the alkoxysilanes mentioned above include the alkoxysilane represented by the following general formula (8). 5 y R 6 z Si ( OR 7 ) 4-y-z (8) (In formula (8), R 5 R is independently an unsubstituted or substituted monovalent hydrocarbon group having 6 to 15 carbon atoms that does not have an aliphatic unsaturated bond, 6 R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, 7 (Each is independently an alkyl group having 1 to 6 carbon atoms, where y is a number from 0 to 2, preferably 1, and z is a number from 0 to 2, preferably 0 or 1, provided that y + z is 1 or 2.)

[0039] In the above formula (8), R 5 The unsubstituted or substituted monovalent hydrocarbon group represented by is a monovalent hydrocarbon group having 6 to 15 carbon atoms, preferably 8 to 12, and lacking an aliphatic unsaturated bond, preferably a linear alkyl group. Using the alkyl group satisfying this range results in good wettability of component (C) and good handling of this component. 5 Specific examples include alkyl groups such as hexyl, octyl, nonyl, decyl, dodecyl, and tetradecyl groups.

[0040] In the above formula (8), R 6The monovalent hydrocarbon group represented by has 1 to 8 carbon atoms, preferably 1 to 6. Specific examples include alkyl groups, cycloalkyl groups, alkenyl groups, and more specifically, alkyl groups such as methyl, ethyl, propyl, hexyl, and octyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; alkenyl groups such as vinyl and allyl groups; aryl groups such as phenyl and tolyl groups; aralkyl groups such as 2-phenylethyl and 2-methyl-2-phenylethyl groups; and halogenated hydrocarbon groups such as 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl, 2-(heptadecafluorooctyl)ethyl, and p-chlorophenyl groups, in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as chlorine and fluorine atoms. Preferably, these are methyl, ethyl, vinyl, and phenyl groups.

[0041] In the above formula (8), R 7 The alkyl group represented by has 1 to 6 carbon atoms, preferably 1 to 2. Specific examples include methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, with methyl and ethyl groups being preferred.

[0042] A specific example of an alkoxysilane represented by the above formula (8) is C6H 13 Si(OCH3)3, C 10 H 21 Si(OCH3)3, C 12 H 25 Si(OCH3)3, C 12 H 25 Si(OC2H5)3,C 10 H 21 Si(CH3)(OCH3)2,C 10 H 21 Si(C6H5)(OCH3)2,C 10 H 21 Si(CH3)(OC2H5)2,C 10 H 21 Si(CH=CH2)(OCH3)2,C 10 H 21 Examples include Si(CH2CH2CF3)(OCH3)2.

[0043] The amount of wettability improver added is preferably 10 to 10,000 parts by mass, more preferably 50 to 6,000 parts by mass, and even more preferably 100 to 5,000 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). When this range is satisfied, the wettability of component (C) will be good. This wettability improver may be used alone or in combination of two or more types.

[0044] <Non-reactive organopolysiloxane> A non-reactive organopolysiloxane is an organopolysiloxane (component (E)) that does not have reactive groups in its molecule, and can suitably adjust the viscosity and workability of the resulting composition. The molecular structure of this non-reactive organopolysiloxane is not particularly limited and may be linear or branched.

[0045] Examples of the reactive groups include hydrogen atoms bonded to silicon atoms, hydroxyl groups (i.e., silanol groups) bonded to silicon atoms, alkoxy groups, amino groups, carboxyl groups, epoxy groups, vinyl groups, mercapto groups, and methacryloxy groups bonded to silicon atoms.

[0046] While not particularly limited, non-reactive organopolysiloxanes such as dimethylpolysiloxane and phenylmethylpolysiloxane are preferred from an economic standpoint.

[0047] The non-reactive organopolysiloxane has a kinematic viscosity at 25°C, preferably between 10 and 1,000,000 mm². 2 / s, more preferably 100 to 100,000 mm 2 It is / s.

[0048] The amount of non-reactive organopolysiloxane is preferably 0 to 100 parts by mass, more preferably 0 to 50 parts by mass, and even more preferably 0 to 30 parts by mass, relative to 100 parts by mass of the total of components (A) and (B). This non-reactive organopolysiloxane may be used alone or in combination of two or more types.

[0049] <Manufacturing Method> The heat-dissipating silicone composition of the present invention is manufactured by a method comprising: (1) a step of uniformly mixing the components (A) to (C) (or components (A) to (E)) to obtain a paste-like composition; (2) a step of mixing the paste-like composition at room temperature (1 to 30°C) for an arbitrary time to obtain a paste-like composition in which a cross-linked structure has been formed; and (3) a step of shear mixing the paste-like composition in which the cross-linked structure has been formed at a temperature of 50°C or lower.

[0050] Mixing includes, for example, mixing by stirring, or kneading using a mixer or the like, as described later.

[0051] Step (1) Step (1) is a step to obtain a paste-like composition in which components (A) to (C) are uniformly mixed. This paste-like composition may be obtained by any means, for example, by mixing a pre-mixed mixture of components (A) and (C) with component (B), or by mixing a pre-mixed mixture of components (B) and (C) with component (A), or by mixing components (A) to (C) all at once. Specifically, it can be obtained, for example, by the following method.

[0052] First, components (A) to (C) are mixed together with a wettability enhancer (component (D)), a non-reactive organopolysiloxane (component (E)), etc., as needed, by stirring, and stirring is continued until the mixture becomes a paste, thereby obtaining a paste-like composition.

[0053] Step (2) Step (2) is a step in which the paste-like composition is mixed at room temperature (1 to 30°C) to promote the addition reaction. In this step, the reaction between component (A) and component (B) proceeds and a cross-linked structure is formed in the composition.

[0054] The paste-like composition is mixed at room temperature without heating. The addition reaction proceeds as the mixing continues, and the reaction is completed (maturation state).

[0055] The mixing time is until the paste-like composition has finished maturing, and is not particularly limited, but is usually 30 minutes to 5 hours, and preferably 1 to 3 hours to ensure proper maturation.

[0056] Step (3) Step (3) is a step of shear mixing the matured paste-like composition (paste-like composition in which a cross-linked structure has been formed) at a temperature of 50°C or lower, preferably 45°C or lower, more preferably 40°C or lower. This step yields the thermally conductive silicone composition of the present invention. In step (3), cooling may be performed as needed, either by natural heat dissipation or by a cooling device. Shear mixing can be performed using, for example, a planetary mixer, a three-roll mill, a two-roll mill, a kneader, a disper, a Shinagawa mixer, a supermascolloider, a Trimix, a Twinmix, or a combination thereof.

[0057] If the temperature during shear mixing is 50°C or lower, sufficient shear force can be imparted to the paste-like composition. Furthermore, excessive cooling does not improve the shear force, and in order to maintain good workability, the cooling is preferably performed between 0 and 50°C, and more preferably between 10 and 40°C. By going through this step (3), the viscosity and dispensability of the composition can be adjusted.

[0058] The viscosity of the obtained composition is not particularly limited, but is preferably 100 to 1,000 Pa·s, and more preferably 200 to 800 Pa·s. The viscosity was measured using a Malcolm viscometer at 25°C.

[0059] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way by these examples. In the examples, the kinematic viscosity is measured at 25°C.

[0060] (A) Component (A-1) A linear kinematic viscosity of 180 mm², having anhydrous groups at both ends, represented by the following formula (9). 2 / s Dimethylpolysiloxane (anhydrous equivalent: 1550 g / mol, specific gravity: 1.0) (A-2) A linear kinematic viscosity of 150 mm² having anhydrous groups at both ends, represented by the following formula (10) 2 Dimethylpolysiloxane (anhydrous equivalent: 973 g / mol, specific gravity: 1.0)

[0061] (B) Component (B-1) Organodimethylpolysiloxane represented by the following average composition formula (11) (amine value: 3770 g / mol, specific gravity: 1.0) (B-2) Organodimethylpolysiloxane represented by the following average composition formula (12) (amine value: 1600 g / mol, specific gravity: 1.0)

[0062] (C) Components (C-1) Aluminum powder (average particle size: 36 μm, specific gravity: 2.71) (C-2) Aluminum powder (average particle size: 11 μm, specific gravity: 2.71) (C-3) Aluminum powder (average particle size: 2 μm, specific gravity: 2.71) (C-4) Zinc oxide powder (average particle size: 0.25 μm, specific gravity: 5.67)

[0063] (D) Component (D-1) Alkyl group-containing organopolysiloxane represented by the following formula (13) (Specific gravity: 1.0)

[0064] The viscosity of the composition was measured at 25°C using a rotational viscometer, specifically a Malcolm viscometer (Type PC-10AA) manufactured by Malcolm Corporation.

[0065] Thermal conductivity of the compositions The thermal conductivity of the compositions was measured at 25°C using a measuring device (TPS-2500S manufactured by Kyoto Electronics Manufacturing Co., Ltd.) that conforms to the hot disk method in accordance with ISO 22007-2.

[0066] Composition Shear Displacement Test A 0.25 mm spacer was placed between an aluminum plate (80 mm x 50 mm) and a glass plate (80 mm x 50 mm) to sandwich the composition in a circular shape with a diameter of 1.6 cm. This test specimen was positioned at a 90° angle to the plane and subjected to a 500-cycle test using a thermal shock tester (manufactured by ESPEC Corporation (model number: TSE-11-A)) set to alternately cycle between -40°C and 125°C (30 minutes each). After 500 cycles, the amount the composition had displaced from its original position was measured. Judgment Criteria: Shear resistance was evaluated as excellent if the displacement was 2 mm or less.

[0067] The appearance of the composition after the shear test was observed. The state of the composition after 500 cycles was observed. A state without voids or cracks in the composition was marked with ○, and a state with voids or cracks was marked with ×.

[0068] Examples 1-10 As shown in Table 1, each component was added and the composition was prepared according to the following procedure. Step (1): Components (A), (B), (C), and optionally (D) were added to a planetary mixer and stirred and mixed at room temperature until it became a paste. Step (2): The paste composition obtained in Step (1) was stirred at room temperature for 2 hours to induce an addition reaction and obtain a composition having a crosslinked structure. Step (3): The composition obtained in Step (2) was stirred at 50°C or below for a further 1 hour.

[0069] The above-described tests and measurements were performed using the obtained compositions. The results are shown in Table 1.

[0070]

[0071] In Examples 1 to 10, components (A) and (B) formed a cross-linked structure in the composition, resulting in excellent shear resistance with shear values ​​of 2 mm or less in the shear test. Furthermore, in Examples 1 to 10, the viscosity after step (3) was 400 Pa·s or less, indicating good workability.

[0072] Comparative Examples 1-2 Instead of component (A-1) of Examples 1-9, a linear kinematic viscosity of 600 mmHg with vinyl groups at both ends of (a-1) was used. 2 / s dimethylpolysiloxane (Vi value: 0.015 mol / 100g, specific gravity: 1.0) and (B-1) instead of component (b-1) the following average formula (14) The following composition was prepared using an organohydrogenpolysiloxane (H value: 0.005 mol / g, specific gravity: 1.0) represented by (a-1), (c-1) aluminum oxide powder (average particle size: 75 μm, specific gravity: 3.98), (c-2) aluminum oxide powder (average particle size: 2 μm, specific gravity: 3.98), (c-3) Fe-Cr-Si soft magnetic powder (average particle size: 8 μm, specific gravity: 7.90), the (D-1) component used in the example, a solution of platinum-divinyltetramethyldisiloxane complex dissolved in the same dimethylpolysiloxane as (a-1) above (platinum atom content: 1% by mass, specific gravity: 1.0) as a reaction catalyst, and ethinylcyclohexanol (specific gravity: 1.0) as a control agent. Each component was charged as shown in Table 2, and the composition was prepared according to the following procedure.

[0073] Step (1'): Components (a-1), (c-1), (c-2), and (D-1) were placed in a planetary mixer and stirred at room temperature until a paste was formed. Then, the above-mentioned control agent component was added and stirred for 10 minutes, and then the above-mentioned reaction catalyst component was added and stirred for another 10 minutes. Finally, component (b-1) was added and stirred for 10 minutes to complete step (1'). Step (2'): The paste-like composition obtained in step (1') was heated to 160°C and heated and stirred for 2 hours to promote the hydrosilylation reaction, and then heated and stirred for another hour to allow it to mature and obtain a composition with a crosslinked structure. Step (3'): The composition obtained in step (2') was cooled to room temperature and stirred at room temperature for 1 hour to complete the preparation of the composition.

[0074] The above-described tests and measurements were performed using the obtained compositions. The results are shown in Table 2.

[0075]

[0076] In the conventional compositions of Comparative Examples 1 and 2, a platinum catalyst was used, and in step (2'), heating (up to 160°C) was required to activate the reaction between Si-Vi and Si-H (hydrosilylation), followed by high-temperature heating and stirring. On the other hand, in the present invention, by mixing an organosiloxane having an organic group having an acid anhydride group with an organosiloxane having an amino group at room temperature, the amide bond obtained by the addition reaction between the acid anhydride group and the amino group is used as the crosslinking portion of the silicone gel, making it possible to obtain a thermally conductive silicone composition under environmentally friendly mild conditions without requiring heating at temperatures higher than 50°C.

Claims

1. A thermally conductive silicone composition containing the reaction product of component (A) and component (B) below, and component (C). (A) An organopolysiloxane having an organic group having an acid anhydride group bonded to a silicon atom, and not having an alkoxy group bonded to a silicon atom. (B) An organopolysiloxane having an amino group. (C) A thermally conductive filler.

2. The thermally conductive silicone composition according to claim 1, further comprising an alkoxy group-containing organopolysiloxane represented by the following general formula (1) as component (D). (In formula (1), R 1 R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, 2 (Each is an alkyl group having 1 to 6 carbon atoms, and P is a number between 5 and 120.) 3. The amount of component (B) blended is such that there are 0.1 to 3.0 moles of amino groups in the organopolysiloxane molecule of component (B) relative to 1 mole of acid anhydride groups bonded to silicon atoms in the organopolysiloxane molecule of component (A), and the amount of component (C) blended is such that it amounts to 30 to 95% by volume in the thermally conductive silicone composition, as described in claim 1.

4. The thermally conductive silicone composition according to claim 1, wherein component (A) is an organopolysiloxane of the following average composition formula (2): R''R2SiO-(R2SiO) n -SiR2R'' (2) (In formula (2), R is independently a hydrocarbyl group having 1 to 8 carbon atoms, R'' is independently an organic group having an acid anhydride group, and n is a number from 0 to 200.) 5. The thermally conductive silicone composition according to claim 4, wherein the organic group having an acid anhydride group in R'' of formula (2) is the group represented by the following formula (3). (In formula (3), X is a hydrogen atom or a hydrocarbyl group having 1 to 8 carbon atoms, and a is a number from 1 to 6.) 6. The thermally conductive silicone composition according to claim 5, wherein X in formula (3) is independently selected from a hydrogen atom and an aromatic group, and a is 2, or X is a hydrogen atom and a is 3.

7. A method for producing a thermally conductive silicone composition according to any one of claims 1 to 6, comprising the following steps (1) to (3): (1) a step of uniformly mixing the components (A) to (C) to obtain a paste-like composition; (2) a step of mixing the paste-like composition at room temperature to obtain a paste-like composition in which a crosslinked structure has been formed; and (3) a step of shear mixing the paste-like composition in which the crosslinked structure has been formed at a temperature of 50°C or lower.

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