JP6933198B2 - Thermally conductive silicone composition and its manufacturing method - Google Patents

Description

The present invention relates to a thermally conductive silicone composition, and relates to a thermally conductive silicone composition having excellent coating performance and slip resistance in a wide temperature range, and a method for producing the same.

In general, electrical and electronic components generate heat during use, so it is necessary to remove heat in order for these parts to operate properly. Conventionally, various thermally conductive materials used for removing heat have been used. Proposed. In this case, there are two types of thermally conductive materials: (1) a sheet-like material that is easy to handle, and (2) a paste-like material called heat-dissipating grease.

The sheet-shaped material (1) has the advantage of not only being easy to handle but also having excellent stability, but the contact thermal resistance is inevitably large, so the heat dissipation performance is inferior to that of the heat dissipation grease. It will be. Further, since a certain amount of strength and hardness are required to maintain the sheet shape, it is not possible to absorb the tolerance generated between the element and the housing, and the stress may destroy the element.

On the other hand, in the case of the heat-dissipating grease of (2), not only can it be applied to mass production of electrical and electronic products by using a coating device or the like, but also the contact thermal resistance is low, so that the heat-dissipating performance is excellent. There is. However, when the viscosity of the heat-dissipating grease is lowered in order to obtain good coating performance, the heat-dissipating grease shifts due to the thermal shock of the element (pump-out phenomenon), resulting in insufficient heat reduction, and as a result, the element becomes It may cause a malfunction.

Therefore, a specific organopolysiloxane, a thickener such as zinc oxide, alumina, aluminum nitride, boron nitride, silicon carbide, etc., an organopolysiloxane having at least one hydroxyl group directly connected to a silicon atom in one molecule, and an alkoxy A grease-like silicone composition (Patent Document 1: JP-A-11-4995) and liquid silicone in which bleeding of the base oil is suppressed in combination with silane, and heat having a constant thermal conductivity and a moth hardness of 6 or more. A thermally conductive silicone composition having excellent thermal conductivity and dispensability, which is a combination of a conductive inorganic filler and a thermally conductive inorganic filler having a certain thermal conductivity and a moth hardness of 5 or less (patented). Document 2: JP-A-11-246884), a thermally conductive grease composition obtained by combining a specific base oil and a metallic aluminum powder having an average particle size of 0.5 to 50 μm (Patent Document 3: JP-A-2000). -63873), a silicone grease composition in which the filling rate of aluminum nitride in the silicone grease is increased by mixing and using two types of aluminum nitride powders having different average particle sizes (Patent Document 4: JP-A-2000). -1698773), a silicone grease composition that increases the viscosity of the oil and suppresses bleed-out (Patent Document 5: JP-A-2003-301184), and other higher-performance thermally conductive silicone compositions have been proposed. I came. However, there has not yet been a product that can sufficiently cope with the high performance of the electronic and electrical parts used.

Japanese Unexamined Patent Publication No. 11-4995 JP-A-11-246884 Japanese Unexamined Patent Publication No. 2000-63873 Japanese Unexamined Patent Publication No. 2000-1698773 Japanese Unexamined Patent Publication No. 2003-301184

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermally conductive silicone composition having excellent coatability and slip resistance in a wide temperature range, and a method for producing the same.

As a result of diligent studies to achieve the above object, the present inventor has determined that (A) an organopolysiloxane having an alkenyl group bonded to a silicon atom and (B) an organohydrogenpolysiloxane in a specific molar ratio (Si-). Organohydrogenpolysiloxane, which has two or more (C) Si-H groups and is added to the reaction product reacted with H / Si-Vi) and the reaction product of the components (A) and (B). Good coatability and displacement resistance in a wide temperature range by combining (D) an inorganic filler having a specific average particle size and (E) a thermally conductive inorganic filler having a specific average particle size in a specific amount. It was found that the above can be obtained, and the present invention was made.

Therefore, the present invention provides the following thermally conductive silicone composition and a method for producing the same.
1. 1. Organopolysiloxane having (A) an alkenyl group bonded to a silicon atom and (B) organohydrogenpolysiloxane are combined with an alkenyl group bonded to a silicon atom in (A) component and Si- in (B) component. Reactants reacted at a molar ratio (Si—H / Si—Vi) of 2 to 8 with H groups,
(C) Organohydrogenpolysiloxane having two or more Si—H groups: The molar ratio (Si—H) of the alkenyl group bonded to the silicon atom in the component (A) to the Si—H group in the component (C). / Si-Vi) Amount of 2 to 8,
(D) Inorganic filler with an average particle size of 3 μm or less selected from metal oxides and metal nitrides, and (E) Thermally conductive inorganic filler with an average particle size of 5 μm or more.
The heat conductive silicone composition containing the above, wherein the total content of the components (D) and (E) is 200 to 100 parts by mass with respect to the total of 100 parts by mass of the components (A), (B) and (C). A thermally conductive silicone composition having 6,000 parts by mass and an absolute viscosity at 25 ° C. of 100 to 800 Pa · s.
2. Rheometer measurement under the following conditions Measuring jig: Parallel plate P20 TL
Measurement gap: 1.00 mm (liquid volume: 4.0 mL)
Measurement mode: Fixed deformation amount-Frequency dependence measurement Deformation condition: CD-Auto Straight 1.00 ± 0.05%
Measurement frequency: 0.1 to 10Hz
Measurement temperature: 25 ° C ± 1 ° C, after raising to 150 ° C at 15 ° C / min, 150 ° C ± 1 ° C
The heat according to 1 is described in which G'(25 ° C.) is 6,000 Pa or more and the ratio of G'(150 ° C.) / G'(25 ° C.) is 1.2 to 10 when the storage elastic modulus is measured. Conductive silicone composition.
3. 3. The component (D) is 1 or 2 selected from aluminum oxide powder, zinc oxide powder, magnesium oxide, aluminum nitride and boron nitride powder having a PZC (point of zero charge) of pH 6 or higher. The thermally conductive silicone composition according to the above.
4. (I) In the alkenyl group and the component (B) in which the components (A), (B), (D) and (E) and the platinum group metal-based curing catalyst are bonded to the silicon atom in the component (A). And the step of mixing so that the molar ratio (Si—H / Si—Vi) with the Si—H group is 2 to 8.
(II) The step of heating the obtained mixture at 100 to 180 ° C. for 30 minutes to 4 hours to react the component (A) and the component (B), and
(III) The step of cooling the reactant after the reaction and
(IV) After cooling, the step of adding the component (C) to the reaction product and mixing it.
The method for producing a thermally conductive silicone composition according to any one of 1 to 3, which comprises.

According to the present invention, it is possible to provide a thermally conductive silicone composition having excellent coatability and slip resistance in a wide temperature range, and a method for producing the same. This thermally conductive silicone composition is suitable for removing heat from electrical and electronic components that generate heat during use. Hereinafter, the "thermally conductive silicone composition" may be referred to as a "silicone composition".

Hereinafter, the present invention will be described in detail.
[Organopolysiloxane]
The organopolysiloxane of the present invention comprises (A) an organopolysiloxane having an alkenyl group bonded to a silicon atom and (B) an organohydrogenpolysiloxane having an alkenyl group bonded to a silicon atom in the component (A). (B) A reaction product reacted at a molar ratio (Si—H / Si—Vi) of 2 to 8 with the Si—H group in the component. Hereinafter, it may be simply described as "(A), (B) component reaction product".

[(A) component]
The alkenyl group-containing organopolysiloxane has an average of at least one alkenyl group bonded to a silicon atom in one molecule, preferably at least two (usually 2 to 20) per molecule, more preferably 2 to 10. It has about one. These can be used alone or in combination of two or more.

The molecular structure of the component (A) is not particularly limited, and examples thereof include a linear structure, a linear structure having a partial branch, a branched chain structure, a cyclic structure, and a cyclic structure having a branch. It is preferably a linear organopolysiloxane. Specifically, the molecular chain is mainly composed of repeating diorganosiloxane units, and both ends of the molecular chain are sealed with a triorganosyloxy group. It is preferably diorganopolysiloxane. Further, the component (A) may be a polymer composed of a single siloxane unit or a copolymer composed of two or more types of siloxane units. Further, the position of the alkenyl group bonded to the silicon atom in the component (A) is not particularly limited, and this alkenyl group is either a silicon atom at the end of the molecular chain or a silicon atom at the non-terminal of the molecular chain (in the middle of the molecular chain). It may be bound only to, or it may be bound to both of them.

As the component (A), for example, the following average composition formula (1)
R ¹ _m R ² _n SiO _{(4-mn) / 2} (1)
(In the formula, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, R ² independently represents an alkenyl group, and m is 0.5 to 2.5. , Preferably a positive number of 0.8 to 2.2, n is a positive number of 0.0001 to 0.2, preferably 0.0005 to 0.1, where m + n is usually 0. It is a positive number of 8 to 2.7, preferably 0.9 to 2.2.)
An organopolysiloxane represented by and having at least one alkenyl group bonded to a silicon atom can be mentioned.

Examples of the R ¹ include an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond having 1 to 10 carbon atoms. Specific examples of R ¹ include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, hexyl group, octyl group and decyl group; phenyl group, trill group, etc. Aryl groups such as xsilyl group and naphthyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aralkyl groups such as benzyl group, 2-phenylethyl group and 3-phenylpropyl group; Part or all of the bonded hydrogen atoms are halogen atoms such as chlorine atom, bromine atom and iodine atom; groups substituted with cyano group and the like, for example, chloromethyl group, 2-bromoethyl group, 3,3,3-tri Fluoropropyl group, cyanoethyl group and the like can be mentioned.

Among these, a methyl group, a phenyl group, or a combination of both of them is preferable. The ^{component (A) in which R 1} is a methyl group, a phenyl group, or a combination of both is easy to synthesize and has good chemical stability. When an organopolysiloxane having particularly good solvent resistance is used as the component (A), R ¹ is a methyl group, a phenyl group, or a combination thereof and a 3,3,3-trifluoropropyl group. It is more preferable that it is a combination.

Examples of the R ² include an alkenyl group having 2 to 8 carbon atoms. Specific examples of R ² include a vinyl group, an allyl group, a 1-propenyl group, an isopropenyl group, a 1-butenyl group, an isobutenyl group, a hexenyl group and the like. Of these, a vinyl group is preferable. The ^{component (A) in which R 2} is a vinyl group is easy to synthesize and has good chemical stability.

Specific examples of the component (A) include a trimethylsiloxy group-blocking dimethylsiloxane / methylvinylsiloxane copolymer at both ends of the molecular chain, a trimethylsiloxy group-blocking methylvinylpolysiloxane at both ends of the molecular chain, and a trimethylsiloxy group-blocking dimethyl at both ends of the molecular chain. Siloxane / methylvinylsiloxane / methylphenylsiloxane copolymer, trimethylsiloxy group-blocking at both ends of the molecular chain dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, dimethylvinylsiloxy group-blocking at both ends of the molecular chain dimethylpolysiloxane, both molecular chains Ended dimethylvinylsiloxy group-blocked methylvinylpolysiloxane, both ends of the molecular chain dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, both ends of the molecular chain dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane Polymer, dimethylvinylsiloxy group-blocked dimethylpolysiloxane at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane / diphenylsiloxane copolymer, divinylmethylsiloxy group-blocked dimethylpolysiloxane at both ends of the molecular chain, trivinylsiloxy group-blocked dimethylpolysiloxane at both ends of the molecular chain And so on. These organopolysiloxanes may be used alone, in combination of two or more, or in combination of one or two or more having different degrees of polymerization.

The viscosity of the component (A) at 25 ° C. is preferably 0.1 to 20,000 mPa · s, more preferably 10 to 1,000 mPa · s. If the viscosity is too low, the thermally conductive inorganic filler of the obtained silicone composition tends to settle, which may result in poor long-term storage stability. Further, if the viscosity is too high, the obtained silicone composition tends to be remarkably lacking in fluidity, and the workability may be inferior. In the present invention, the absolute viscosity value is a value measured by a spiral viscometer such as a Malcolm viscometer (type PC-10AA).

[(B) component]
The component (B) is an organohydrogenpolysiloxane having a hydrogen atom (Si—H group) bonded to one or more silicon atoms in one molecule, and is used alone or in combination of two or more. be able to. The organohydrogenpolysiloxane of the component (B) is a curing agent for a silicone composition, preferably an average of 3 or more, more preferably 4 or more (usually about 4 to 300), and further preferably about 4 to 300 in one molecule. It has 5 or more (for example, about 5 to 200) hydrogen atoms (Si—H groups) bonded to silicon atoms. The molecular structure of the component (B) is not particularly limited, and may be, for example, any of a resin-like material having a linear, branched, cyclic, or three-dimensional network structure, and the following average composition formula (2). ) Can be used.

R ³ _p1 H _q1 SiO _{(4-p1-q1) / 2} (2)
(In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group excluding the aliphatic unsaturated hydrocarbon group. P1 is 1.0 to 3.0, preferably 0.5 to 2.5, q1 is 0.05 to 2.0, preferably 0.01 to 1.0, and p1 + q1 is a positive number satisfying 0.5 to 3.0, preferably 0.8 to 2.5. )

^{R 3} in the formula (2) includes an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, an isobutyl group, a tert-butyl group and a cyclohexyl group; a phenyl group, An aliphatic unsaturated bond such as an aryl group such as a trill group or a xylyl group; an aralkyl group such as a benzyl group or a phenethyl group; an alkyl halide group such as a 3-chloropropyl group or a 3,3,3-trifluoropropyl group. Except for the above, usually, unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms and the like are exemplified. Methyl group, ethyl group, propyl group, phenyl group, 3,3,3-trifluoropropyl group are preferable, and methyl group is more preferable.

Specific examples of the organohydrogenpolysiloxane of the component (B) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and methylhydrogencyclo. Polysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, tris (dimethylhydrogensiloxy) methylsilane, tris (dimethylhydrogensiloxy) phenylsilane, dimethylhydrogensiloxy group-blocking at both ends of the molecular chain dimethylsiloxane / methylhydrogen Siloxane, dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane at both ends of the molecular chain, trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends of the molecular chain, dimethylhydrogensiloxy group-blocked dimethylpolysiloxane at both ends of the molecular chain, molecule Dimethylhydrogensiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer at both ends of the chain, trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both ends of the molecular chain, trimethylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane at both ends of the molecular chain・ Methylhydrogensiloxane copolymer, dimethylhydrogensiloxy group-blocked dimethylsiloxane at both ends of the molecular chain ・ Methylhydrogensiloxane copolymer, H (CH ₃ ) ₂ SiO _1/2 unit and SiO ₂ unit copolymer , H (CH ₃ ) ₂ SiO _1/2 unit and (CH ₃ ) ₃ SiO _1/2 unit and SiO ₂ unit copolymers, and mixtures of two or more of these organohydrogenpolysiloxanes. Be done.

The viscosity of the component (B) at 25 ° C. is not particularly limited, but is preferably 0.5 to 1,000,000 mPa · s, more preferably 1 to 100,000 mPa · s. The organohydrogenpolysiloxane as the component (B) preferably has 3 to 500 silicon atoms (or degree of polymerization) in one molecule, particularly preferably about 4 to 300.

The present invention comprises a reaction product having a molar ratio (Si—H / Si—Vi) of 2 to 8 of an alkenyl group bonded to a silicon atom in the component (A) and a Si—H group in the component (B). Since it is a waste, the component (A) and the component (B) are blended so as to fall within such a range. The molar ratio is more preferably 2.0 to 7.0, and even more preferably 3.0 to 6.0. When the molar ratio is 0 <Si—H / Si—Vi <2.0, the viscosity is increased and the coating performance is significantly deteriorated. In particular, when the molar ratio is 0 <Si-H / Si-Vi <1.0, there is a possibility of reacting with Si-H of the component (C) to be added later, and over time in a high heat usage environment. Hardness increases and stress is generated, which may damage electronic devices. On the other hand, if the upper limit of the molar ratio range is exceeded, the elastic modulus may decrease at room temperature or in a low temperature environment, and the silicone composition may be displaced during the thermal cycle. Further, when Si−H / Si−Vi> 8.0, the ratio of G'(150 ° C.) / G'(25 ° C.) at high temperature becomes large, but G from 25 ° C. to 150 ° C. 'Decreases and a gap occurs.

The silicone composition preferably contains a platinum group metal-based curing catalyst which is an addition reaction catalyst for accelerating the reaction, and examples of the catalyst used in the hydrosilylation reaction include well-known catalysts. These can be used alone or in combination of two or more. A hydrosilylation catalyst in which a platinum complex such as chloroplatinic acid or chloroplatinate is diluted with an organopolysiloxane having a vinyl group such as an alkenyl group is preferable. This can be obtained by mixing a platinum complex with an organopolysiloxane having a vinyl group. When the platinum complex contains a solvent such as toluene, it is advisable to remove the solvent after mixing.

When an addition reaction catalyst is used, a so-called catalyst amount may be used, and usually, it is preferably about 0.1 to 2,000 ppm in terms of the mass of the platinum group metal element with respect to the component (A).

[(C) component]
The component (C) is an organohydrogenpolysiloxane having a hydrogen atom (Si—H group) bonded to two or more silicon atoms in one molecule, and is used alone or in combination of two or more. be able to. The organohydrogenpolysiloxane of the component (C) does not function as a curing agent for the silicone composition and does not react with the component (A). The molecular structure of the component (C) is not particularly limited, and may be, for example, any of a resin-like substance having a linear, branched, cyclic, or three-dimensional network structure. (B) It may be the same as or different from the component. As the component (C), a component represented by the following average composition formula (3) can be used.

R ³ _p2 H _q2 SiO _{(4-p2-q2) / 2} (3)
(In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group excluding the aliphatic unsaturated hydrocarbon group. P2 is 1.0 to 3.0, preferably 0.5 to 2.5, q2 is 0.05 to 2.0, preferably 0.01 to 1.0, and p2 + q2 is a positive number satisfying 0.5 to 3.0, preferably 0.8 to 2.5. )

^{R 3} in the formula (3) includes an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, an isobutyl group, a tert-butyl group and a cyclohexyl group; a phenyl group, An aliphatic unsaturated bond such as an aryl group such as a trill group or a xylyl group; an aralkyl group such as a benzyl group or a phenethyl group; an alkyl halide group such as a 3-chloropropyl group or a 3,3,3-trifluoropropyl group. Except for the above, usually, unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms and the like are exemplified. Methyl group, ethyl group, propyl group, phenyl group, 3,3,3-trifluoropropyl group are preferable, and methyl group is more preferable.

Specific examples of the organohydrogenpolysiloxane of the component (C) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and methylhydrogencyclo. Polysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, tris (dimethylhydrogensiloxy) methylsilane, tris (dimethylhydrogensiloxy) phenylsilane, dimethylhydrogensiloxy group-blocking at both ends of the molecular chain dimethylsiloxane / methylhydrogen Siloxane, dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane at both ends of the molecular chain, trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends of the molecular chain, dimethylhydrogensiloxy group-blocked dimethylpolysiloxane at both ends of the molecular chain, molecule Dimethylhydrogensiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer at both ends of the chain, trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both ends of the molecular chain, trimethylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane at both ends of the molecular chain・ Methylhydrogensiloxane copolymer, dimethylhydrogensiloxy group-blocked dimethylsiloxane at both ends of the molecular chain ・ Methylhydrogensiloxane copolymer, H (CH ₃ ) ₂ SiO _1/2 unit and SiO ₂ unit copolymer , H (CH ₃ ) ₂ SiO _1/2 unit and (CH ₃ ) ₃ SiO _1/2 unit and SiO ₂ unit copolymers, and mixtures of two or more of these organohydrogenpolysiloxanes. Be done.

The viscosity of the component (C) at 25 ° C. is not particularly limited, but is preferably 0.5 to 1,000,000 mPa · s, more preferably 1 to 100,000 mPa · s. The organohydrogenpolysiloxane as the component (C) preferably has 2 to 500 silicon atoms (or degree of polymerization) in one molecule, preferably about 3 to 300.

In the present invention, (C) organohydrogenpolysiloxane does not react with the alkenyl group bonded to the silicon atom in the component (A). However, as the blending amount, the molar ratio to the alkenyl group in the component (A) is more preferably 2 to 8. When the molar ratio is 0 <Si—H / Si—Vi <2, there is not enough Si—H in the organohydrogenpolysiloxane of the component (C) with respect to the active site of the component (D). , G'(150 ° C) / G'(25 ° C), which is the storage elastic modulus ratio of 150 ° C and 25 ° C, is less than 1.2 without increasing the elastic modulus at 150 ° C. There is a risk that misalignment may occur or the viscosity of the silicone composition may increase, resulting in a composition having poor coatability. On the other hand, when the molar ratio exceeds 8, the active site of the component (D) is filled with one end of the component (C), and Si in the organopolysiloxane composed of the reaction of the component (A) and the component (B). It becomes impossible to bridge the active site of the component (D) with the −H group or the Si—H group of the component (C), and the storage elastic modulus ratio of the obtained silicone composition at 150 ° C. and 25 ° C. is G'(. 150 ° C.) / G'(25 ° C.) is less than 1.2, and there is a risk that the silicone composition will be displaced during the thermal cycle.

[(D) component]
The component (D) is an inorganic filler having an average particle size of 3 μm or less, which is selected from metal oxides and metal nitrides. This inorganic filler has a large specific surface area and interacts with the (A) and (B) component reactants and the (C) component, which are rich in Si—H groups, to obtain a storage elastic modulus at 150 ° C. It is an ingredient to improve. Further, it is a component for adjusting the particle size distribution of the thermally conductive inorganic filler of the component (E) and making it close-packed to increase the blending amount and improve the thermal conductivity of the silicone composition.

Preferred materials include aluminum oxide powder, zinc oxide powder, magnesium oxide, aluminum nitride, and boron nitride powder. These are insulating materials, and since they are industrially selectable in a wide range of particle sizes, are easily available as resources, and are available at a relatively low cost, they are widely used as heat radiating materials. In the case of metal oxides, there are -OH residues on the surface, and in the case of metal nitrides, there are -NH ₂ residues on the surface, so they interact with Si-H residues present in organopolysiloxane. You can expect to do it.

Further, the component (D) is preferably an inorganic filler having a PZC (point of zero charge) of pH 6 or higher. If the PZC is less than pH 6, the number of sites that interact with Si—H on the surface of the inorganic filler is reduced, and the storage elastic modulus at 150 ° C. is not improved, so that a deviation may occur. The upper limit is not particularly limited and may be 12 or less. PZC is a pH at which the surface charges of metal oxides and metal nitrides become zero in an aqueous solution.

As the inorganic filler of the component (D) used in the present invention, amorphous, granulated powder, and spherical particles can be used, but among them, it is preferable to use a spherical inorganic filler from the viewpoint of filling property. ..

The average particle size of the component (D) is 3 μm or less, more preferably 0.1 to 2.5 μm. If the average particle size is too small, the fluidity of the silicone composition will decrease, and if the average particle size is too large, the number of sites that interact with Si—H groups will decrease, and a sufficient improvement in storage elastic modulus at 150 ° C. will be achieved. It may not be seen. In the present invention, the average particle diameters of the components (D) and (E) are measured by a laser diffraction / scattering method, for example, a volume cumulative average particle measured by a particle size analyzer manufactured by Nikkiso Co., Ltd., Microtrack MT3300EX. The _{diameter value is D 50} (or median diameter).

The content of the component (D) in the silicone composition is preferably 50 to 4,000 parts by mass, preferably 100 to 3,000 parts by mass, based on 100 parts by mass of the total of the components (A), (B) and (C). Parts by mass are more preferred. If the content of the component (D) is too small, the obtained silicone composition may be displaced or the thermal conductivity may be lowered, while if it is too large, the viscosity becomes high and the silicone composition is uniformly applied. Can be difficult. The component (D) is preferably a mixture of the components (A) and (B) that have been previously heated and mixed.

[(E) component]
The component (E) is a heat conductive inorganic filler having an average particle size of 5 μm or more, and is aluminum, silver, copper, nickel, zinc oxide, aluminum oxide, silicon oxide, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, and carbide. Examples thereof include silicon, diamond, graphite, metallic silicon, etc., and one type can be used alone or two or more types can be used in combination as appropriate. Zinc oxide, aluminum oxide, magnesium oxide, aluminum nitride, and boron nitride overlap with the above component (D), but the average particle size is different.

The average particle size of the component (E) is 5 μm or more, preferably 5 to 200 μm, and more preferably 6 to 100 μm. If the average particle size is smaller than 5 μm, the silicone composition becomes non-uniform and the displacement resistance becomes poor. If the average particle size is too large, the silicone composition may become non-uniform and the displacement resistance may deteriorate.

The content of the component (E) in the silicone composition is preferably 100 to 5,000 parts by mass, preferably 200 to 4,000 parts by mass, based on 100 parts by mass of the total of the components (A), (B) and (C). Parts by mass are more preferred.

The total content of the components (D) and (E) in the silicone composition is 200 to 6,000 parts by mass with respect to the total of 100 parts by mass of the components (A), (B) and (C). 500 to 5,000 parts by mass is preferable. If the total content is less than 200 parts by mass, sufficient thermal conductivity cannot be achieved, and if it exceeds 6,000 parts by mass, sufficient coating performance cannot be obtained. The mass ratio of (D): (E) is preferably 55:45 to 95: 5, more preferably 60:40 to 80:20.

[(F) component]
In order to reduce the viscosity before thermosetting, the silicone composition of the present invention may further contain a hydrolyzable organopolysiloxane as the component (F), and one type alone or two or more types may be appropriately combined. Can be used. The component (F) also has a role of maintaining the fluidity of the silicone composition and imparting good handleability to the composition even when the components (D) and (E) are highly filled in the silicone composition. .. As the component (F), it is preferable to contain an organopolysiloxane represented by the following general formula (4), particularly a trifunctional hydrolyzable organopolysiloxane.

（式中、Ｒ⁴は独立に脂肪族不飽和基を含有しない非置換又は置換の１価炭化水素基である。Ｘ¹、Ｘ²、Ｘ³はＲ⁴又は−Ｒ⁵−ＳｉＲ⁶ _g（ＯＲ⁷）_3-gで示される基であり、それぞれ異なってもよいが、少なくとも１つは−Ｒ⁵−ＳｉＲ⁶ _g（ＯＲ⁷）_3-gである。Ｒ⁵は酸素原子又は炭素数１〜４のアルキレン基、Ｒ⁶は独立に脂肪族不飽和結合を含有しない非置換又は置換の１価炭化水素基であり、Ｒ⁷は独立に炭素数１〜４のアルキル基、アルコキシアルキル基、又はアシル基であり、ｇは１〜３の整数である。ａ及びｂはそれぞれ１≦ａ≦１，０００、０≦ｂ≦１，０００である。）

(In the formula, R ⁴ is an unsubstituted or substituted monovalent hydrocarbon group independently containing no aliphatic unsaturated group. X ¹ , X ² , X ³ are R ⁴ or −R ⁵ −SiR ⁶ _g ( OR ⁷ ) The _{groups represented by 3-g} , which may differ from each other, but at least one is −R ⁵ −SiR ⁶ _g (OR ⁷ ) _3-g . R ⁵ is an oxygen atom or 1 carbon atom. An alkylene group of ~ 4, R ⁶ is an unsubstituted or substituted monovalent hydrocarbon group ^{independently containing no aliphatic unsaturated bond, and R 7} is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, respectively. Alternatively, it is an acyl group, and g is an integer of 1 to 3. A and b are 1 ≦ a ≦ 1,000 and 0 ≦ b ≦ 1,000, respectively.)

（式中、Ｒ⁴は独立に脂肪族不飽和基を含有しない非置換又は置換の１価炭化水素基であり、Ｒ⁷は独立に炭素数１〜４のアルキル基もしくはアルコキシアルキル基、又はアシル基であり、ｃは５〜１００の整数であり、ｇは１〜３の整数である。）
で表されるオルガノポリシロキサン、特に２５℃における粘度が０．００５〜１００ｍＰａ・ｓのオルガノポリシロキサンが好ましい。 The component (F) is the following general formula (5).

(In the formula, R ⁴ is an unsubstituted or substituted monovalent hydrocarbon group ^{independently containing no aliphatic unsaturated group, and R 7} is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, or an acyl. It is a group, c is an integer of 5 to 100, and g is an integer of 1 to 3.)
Organopolysiloxane represented by, particularly organopolysiloxane having a viscosity at 25 ° C. of 0.005 to 100 mPa · s is preferable.

In the above formulas (4) and (5), R ⁴ is an unsubstituted or substituted independently containing no aliphatic unsaturated group, preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 1 3 is a monovalent hydrocarbon group, and examples thereof include a linear alkyl group, a branched chain alkyl group, a cyclic alkyl group, an aryl group, an aralkyl group, and an alkyl halide group. Examples of the linear alkyl group include a methyl group, an ethyl group, a propyl group, a hexyl group and an octyl group. Examples of the branched-chain alkyl group include an isopropyl group, an isobutyl group, a tert-butyl group, and a 2-ethylhexyl group. Examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the aryl group include a phenyl group and a tolyl group. Examples of the aralkyl group include a 2-phenylethyl group and a 2-methyl-2-phenylethyl group. Examples of the alkyl halide group include a 3,3,3-trifluoropropyl group, a 2- (nonafluorobutyl) ethyl group, and a 2- (heptadecafluorooctyl) ethyl group. As R ⁴ , a methyl group and a phenyl group are preferable.

R ⁵ is an oxygen atom or an alkylene group having 1 to 4 carbon atoms, and R ⁶ is an unsubstituted or substituted monovalent hydrocarbon group independently containing no aliphatic unsaturated bond, which is exemplified with respect to ^{R 1 above.} Can be mentioned.

The above R ⁷ is independently an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, or an acyl group. Examples of the alkyl group include alkyl groups having 1 to 4 carbon atoms similar to those exemplified for ^{R 4.} Examples of the alkoxyalkyl group include a methoxyethyl group and a methoxypropyl group. As the acyl group, for example, the number of carbon atoms is preferably 2 to 8, and examples thereof include an acetyl group and an octanoyl group. R ⁷ is preferably an alkyl group, particularly preferably a methyl group or an ethyl group.
a and b are as described above, but a + b is preferably 10 to 50, and c is an integer of 5 to 100, preferably 10 to 50. g is an integer of 1-3, preferably 3. It is preferable to have 1 to 6 OR ^{7 groups in the molecule, particularly 3 or 6.}

The following can be mentioned as a preferable specific example of the component (F).

When the component (F) is blended, the content of the component (F) in the silicone composition is 50 to 300 parts by mass with respect to a total of 100 parts by mass of the components (A), (B) and (C). Is preferable. If it is less than 50 parts by mass, the silicone composition may thicken and cannot be discharged, while if it is more than 300 parts by mass, the viscosity may become too low and the component (F) may bleed.

[Other ingredients]
Any component other than the above can be added to the silicone composition of the present invention as long as the effects of the present invention are not impaired.
The filler may be used alone or in combination of two or more. Examples of the filler include clays such as wollastonite, talc, aluminum oxide, calcium sulfate, magnesium carbonate and kaolin; copper carbonates such as aluminum hydroxide, magnesium hydroxide, graphite, barite and malakite; nickel carbonates such as zarakite. Barium carbonate such as withalite; Strontium carbonate such as strontianite; silicates such as forsterite, sillimanite, mulite, pyrophyllite, kaolinite, vermiculite; non-reinforcing fillers such as diatomaceous soil; Examples thereof include those in which the surface of the filler is treated with an organic silicon compound. When the filler is blended, the content of the filler in the silicone composition is preferably 100 parts by mass or less with respect to 100 parts by mass in total of the components (A), (B) and (C).

An adhesive may be added to improve the adhesiveness of the silicone composition. The adhesive may be used alone or in combination of two or more. Specific examples of the adhesive-imparting agent include alkylalkenyldialkoxysilanes such as methylvinyldimethoxysilane, ethylvinyldimethoxysilane, methylvinyldiethoxysilane, and ethylvinyldiethoxysilane; methylvinyldioxymsilane and ethylvinyldioxymsilane. Alkylalkenyldioxymsilane, etc .; alkylalkenyldiacetoxysilane, such as methylvinyldiacetoxysilane, ethylvinyldiacetoxysilane; alkenylalkyldihydroxysilane, such as methylvinyldihydroxysilane, ethylvinyldihydroxysilane; methyltrimethoxysilane, vinyltri Methoxysilane, allyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxy Organotrialkoxysilanes such as silane, bis (trimethoxysilyl) propane, bis (trimethoxysilyl) hexane; triallyl isocyanurate, diallyl (3-trimethoxysilyl) isocyanurate, tris (3-trimethoxysilylpropyl) isocia Isocyanurate compounds such as nurate, tris (3-triethoxysilylpropyl) isocyanurate, tris (3-tripropoxysilylpropyl) isocyanurate; tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetra (2-ethylhexyl) titanate, Titanium compounds such as titanium ethyl acetonate and titanium acetyl acetonate; ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum tris (acetyl acetonate), aluminum monoacetyl aceto Aluminum compounds such as natebis (ethylacetacetate); examples thereof include zirconium compounds such as zirconium acetylacetonate, zirconium butoxyacetylacetonate, zirconium bisacetylacetonate and zirconium ethylacetacetate.

When the adhesion-imparting agent is blended, the content of the adhesion-imparting agent in the silicone composition is not particularly limited, but is 0.01 to 0.01 to 100 parts by mass in total of the components (A), (B) and (C). 10 parts by mass is preferable.

[Production method]
When producing a silicone composition, for example, those including the following steps can be mentioned.
(I) In the alkenyl group and the component (B) in which the components (A), (B), (D) and (E) and the platinum group metal-based curing catalyst are bonded to the silicon atom in the component (A). Step of mixing so that the molar ratio (Si—H / Si—Vi) with the Si—H group is 2 to 8 (II) The obtained mixture is heated at 100 to 180 ° C. for 30 minutes to 4 hours. , (A) and (B) are reacted with each other (III) A step of cooling the reactant after the reaction (IV) A step of adding the component (C) to the reactant and mixing them after cooling.

Trimix, twin mix, planetary mixer by adding components (I) (A), (B), (D) and (E), a platinum group metal-based curing catalyst, and in some cases component (F) and other components. (All are registered trademarks of Inoue Seisakusho Co., Ltd. mixer), Ultra Mixer (registered trademark of Mizuho Kogyo Co., Ltd. mixer), Hibis Dispermix (registered trademark of Tokushu Kagaku Kogyo Co., Ltd. mixer) Etc. are used for mixing. The temperature at which the liquid material and the inorganic filler are mixed is not particularly limited, and it is preferable to mix at room temperature for 5 to 30 minutes.

(II) After mixing, heat the component (A) and the component (B) at 100 to 180 ° C. for 30 minutes to 4 hours, preferably 1 to 3 hours. After heating, it may be mixed under reduced pressure.
The addition of the component (C) is always carried out after the heating reaction of the components (A) and (B).

(III) Step of cooling the reactant after the reaction It is preferable to cool the reactant at 20 to 40 ° C. after the reaction.
The cooling method is not particularly limited, and a known method can be used.

(IV) Step of adding component (C) to the reaction product after cooling and mixing The addition method and mixing method are not particularly limited, but it is preferable to add component (C) to the reaction product and stir to mix. .. As the mixing device, the same one as in the above step (I) can be used.

[Silicone composition (cured product)]
The thermal conductivity of the silicone composition is preferably 2 W / mK or more, more preferably 3 W / mK or more. The upper limit is not particularly limited, but can be 20 W / mK or less. Since it has such excellent thermal conductivity, it is suitable for heat dissipation.

The absolute viscosity of the silicone composition at 25 ° C. is 100 to 800 Pa · s, preferably 150 to 600 Pa · s. If the absolute viscosity is less than 100 Pa · s, dripping of the silicone composition during coating occurs, and the coatability deteriorates. Furthermore, there is a risk that the components (D) and (E) will settle during long-term storage. On the other hand, if it exceeds 800 Pa · s, the coatability is lowered and the production efficiency is lowered. For example, a silicone composition having an absolute viscosity in the above range can be obtained by adjusting the degree of cross-linking between the components (A) and (B) and the amounts of the components (C) and (D) and (E). be able to.

Further, when the storage elastic modulus is measured under the following rheometer measurement conditions, it is preferable that the ratio of G'(150 ° C.) / G'(25 ° C.) is large from the viewpoint of the balance between the prevention of displacement and the coating performance. G'(25 ° C.) is preferably 6,000 Pa or more, and more preferably 8,000 Pa or more. The upper limit is not particularly limited, but may be 80,000 Pa or less. Moreover, the ratio of G'(150 ° C.) / G'(25 ° C.) is preferably 1.2 to 10, and more preferably 1.5 to 8.0. As the measuring machine, HAAKE MARS (manufactured by Thermo Fisher Scientific) can be used.
Rheometer measurement conditions Measuring jig: Parallel plate P20 TL
Measurement gap: 1.00 mm (liquid volume: 4.0 mL)
Measurement mode: Fixed deformation amount-Frequency dependence measurement Deformation condition: CD-Auto Straight 1.00 ± 0.05%
Measurement frequency: 0.1 to 10Hz
Measurement temperature: 25 ° C ± 1 ° C, after raising to 150 ° C at 15 ° C / min, 150 ° C ± 1 ° C

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The viscosities in the examples are the values of the components (A), (B) and (C) and the viscosities of the silicone composition at 25 ° C. measured by the Malcolm viscometer shown below.

The components used in Examples and Comparative Examples will be described below.
[Addition reaction catalyst]
Placed in a reaction flask chloroplatinic acid _{H 2 PtCl 6 · 6H 2 O} (37.6 wt% platinum) 8.0 g a reflux condenser chloride, thermometer, fitted with a stirrer 100 mL, then 40.0g of ethanol and Jibinirutetora 16.0 g of methyldisiloxane was added. After a heating reaction at 70 ° C. for 50 hours, 16 g of sodium hydrogen carbonate was gradually added while stirring the reaction mixture at room temperature to neutralize the reaction mixture for 2 hours. The reaction mixture was suction-filtered, the filtrate was distilled off under reduced pressure, ethanol and excess divinyltetramethyldisiloxane were substantially removed, and then diluted with toluene to make the total amount 600 g (containing 0.5% by mass of platinum). ..

To the above-mentioned platinum-vinylsiloxane complex toluene solution was added 290 g of dimethylvinylsiloxy group-blocked dimethylpolysiloxane having a viscosity of 600 mPa · s at both ends of the molecular chain, and the mixture was stirred, and toluene was distilled off under reduced pressure at 60 ° C./20 torr, substantially. The catalyst from which toluene was removed was used as a hydrosilylation catalyst (containing 1.0% by mass of platinum).

(A) Component (A-1) Molecular chain with a viscosity of 600 mPa · s Both ends of the molecular chain Dimethylvinylsiloxy group-sealed dimethylpolysiloxane (vinyl group content: 0.015 mol / 100 g)
(A-2) Molecular chain average single-ended dimethylvinylsiloxy group-blocking methylpolysiloxane with a viscosity of 700 mPa · s (vinyl group content: 0.0036 mol / 100 g)

（Ｍｅはメチル基である）（Ｓｉ−Ｈ基含量：０．００５５ｍｏｌ／ｇ）
各シロキサン単位の結合順序は、上記に制限されるものではない。以下同様である。 (B) Component (B-1) Organohydrogenpolysiloxane represented by the following formula

(Me is a methyl group) (Si—H group content: 0.0055 mol / g)
The bonding order of each siloxane unit is not limited to the above. The same applies hereinafter.

（Ｍｅはメチル基である）（Ｓｉ−Ｈ含量 ０．０１０７ｍｏｌ／ｇ） (B-2) Organohydrogenpolysiloxane represented by the following formula

(Me is a methyl group) (Si—H content 0.0107 mol / g)

（Ｍｅはメチル基である）（Ｓｉ−Ｈ基含量：０．００５５ｍｏｌ／ｇ） (C) Component (C-1) Organohydrogenpolysiloxane represented by the following formula

(Me is a methyl group) (Si—H group content: 0.0055 mol / g)

（Ｍｅはメチル基である）（Ｓｉ−Ｈ含量 ０．００１３ｍｏｌ／ｇ） (C-2) Organohydrogenpolysiloxane represented by the following formula

(Me is a methyl group) (Si—H content 0.0013 mol / g)

(D) Inorganic filler D-1: Zinc oxide 2 types (JIS standard, average particle size 1 μm): PZC 9.5
D-2: Magnesium oxide powder (average particle size 1 μm): PZC 11.5
D-3: Silicon carbide (average particle size 1 μm): PZC 4 (comparative product)

(E) Thermally conductive inorganic filler E-1: Aluminum oxide powder (average particle size 10 μm)

(F) F-1: Organopolysiloxane represented by the following formula

(G) G-1: The above platinum hydrosilylation catalyst

A thermally conductive silicone composition having the composition shown in the table was produced by the following method.
[Examples, comparative examples]
Preparation of thermally conductive silicone composition (A), (B), (D), (E), (F) and hydrosilylation catalyst were blended at room temperature and mixed using a planetary mixer for 10 to 30 minutes. (Component (D) was used as a mixture previously heated and mixed with components (A) and (B)). The resulting mixture was heated to 165 ° C. and mixed under reduced pressure for 120 minutes. Then, the heating was stopped and the mixture was cooled to 50 ° C. or lower under the condition of blowing air at room temperature. After cooling, the predetermined component (C) was added, and the mixture was stirred and mixed at room temperature.

The properties of the thermally conductive silicone composition were measured by the following methods.
[Measurement of thermal conductivity]
It was measured at 25 ° C. using TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

[Viscosity measurement]
The viscosity showed a value at 25 ° C., and the measurement was performed using a Malcolm viscometer (type PC-10AA). It is considered that a viscosity exceeding 800 Pa · s cannot be practically used in the coating process of the composition.

[Ratio of storage elasticity of silicone composition at 25 ° C and 150 ° C]
The G'(shear storage elastic modulus) of the obtained silicone composition at 25 ° C. and 150 ° C. and its ratio were measured.
The following conditions Rheometer measuring instrument: HAAKE MARS40
Measuring jig: Parallel plate P20 TL
Measurement gap: 1.00 mm (liquid volume: 4.0 mL)
Measurement mode: Fixed deformation amount-Frequency dependence measurement Deformation condition: CD-Auto Straight 1.00 ± 0.05%
Measurement frequency: 0.1 to 10Hz
Measurement temperature: 25 ° C ± 1 ° C, after raising to 150 ° C at 15 ° C / min, 150 ° C ± 1 ° C
When the storage elastic modulus was measured in, the ratio of G'(150 ° C.) / G'(25 ° C.) was calculated.

[Silicon composition misalignment test]
0.35 mL of the prepared silicone composition was applied onto a glass plate, a 1 mm spacer was inserted, and the prepared silicone composition was sandwiched between the glass plates to prepare a disk-shaped sample having a diameter of about 20 mm and a thickness of 1 mm.
Place the sample sandwiched between the glasses so that the disk is in a vertical state, and perform a cycle test under the conditions of cold test conditions: -40 ° C / 30 minutes ⇔ 150 ° C / 30 minutes. Observed.
When the disk-shaped cured silicone composition was displaced from the original position of the glass plate, it was regarded as "displaced".
When the silicone composition was arranged vertically and no deviation occurred from the original position of the glass plate, it was defined as "no deviation". Such a situation is preferable.

The results shown in Tables 1 to 4 show that the thermally conductive silicone composition of the present invention not only has excellent thermal conductivity, but also does not cause deviation during the thermal cycle even when stored for a long period of time. This demonstrates that it is excellent in removing heat from generated electrical and electronic parts.

The thermally conductive silicone composition of the present invention not only has excellent thermal conductivity, but also has good displacement resistance and coatability over a wide temperature range, so that it can be removed from electrical and electronic parts that generate heat during use. Suitable for heat.

Claims (4)

Organopolysiloxane having (A) an alkenyl group bonded to a silicon atom and (B) organohydrogenpolysiloxane are combined with an alkenyl group bonded to a silicon atom in (A) component and Si- in (B) component. Reactants reacted at a molar ratio (Si—H / Si—Vi) of 2 to 8 with H groups,
(C) Organohydrogenpolysiloxane having two or more Si—H groups: The molar ratio (Si—H) of the alkenyl group bonded to the silicon atom in the component (A) to the Si—H group in the component (C). / Si-Vi) Amount of 2 to 8,
(D) Inorganic filler with an average particle size of 3 μm or less selected from metal oxides and metal nitrides, and (E) Thermally conductive inorganic filler with an average particle size of 5 μm or more.
The heat conductive silicone composition containing the above, wherein the total content of the components (D) and (E) is 200 to 100 parts by mass with respect to the total of 100 parts by mass of the components (A), (B) and (C). A thermally conductive silicone composition having 6,000 parts by mass and an absolute viscosity at 25 ° C. of 100 to 800 Pa · s. Rheometer measurement under the following conditions Measuring jig: Parallel plate P20 TL
Measurement gap: 1.00 mm (liquid volume: 4.0 mL)
Measurement mode: Fixed deformation amount-Frequency dependence measurement Deformation condition: CD-Auto Straight 1.00 ± 0.05%
Measurement frequency: 0.1 to 10Hz
Measurement temperature: 25 ° C ± 1 ° C, after raising to 150 ° C at 15 ° C / min, 150 ° C ± 1 ° C
1 Thermally conductive silicone composition. Claim 1 in which the component (D) is one or more selected from aluminum oxide powder, zinc oxide powder, magnesium oxide, aluminum nitride and boron nitride powder having a PZC (point of zero charge) of pH 6 or higher. Or the thermally conductive silicone composition according to 2. (I) In the alkenyl group and the component (B) in which the components (A), (B), (D) and (E) and the platinum group metal-based curing catalyst are bonded to the silicon atom in the component (A). And the step of mixing so that the molar ratio (Si—H / Si—Vi) with the Si—H group is 2 to 8.
(II) The step of heating the obtained mixture at 100 to 180 ° C. for 30 minutes to 4 hours to react the component (A) and the component (B), and
(III) The step of cooling the reactant after the reaction and
(IV) After cooling, the step of adding the component (C) to the reaction product and mixing it.
The method for producing a thermally conductive silicone composition according to any one of claims 1 to 3, which comprises.