WO2020217634A1

WO2020217634A1 - Thermally conductive silicone composition, method for producing same and thermally conductive silicone cured product

Info

Publication number: WO2020217634A1
Application number: PCT/JP2020/004274
Authority: WO
Inventors: 俊晴森村
Original assignee: 信越化学工業株式会社
Priority date: 2019-04-24
Filing date: 2020-02-05
Publication date: 2020-10-29
Also published as: TW202104442A; TWI822954B; JP7116703B2; JP2020180200A

Abstract

The present invention is a thermally conductive silicone composition which is characterized by containing (A) an organopolysiloxane that has at least two alkenyl groups in each molecule, (B) an organohydrogen polysiloxane that has at least two hydrogen atoms, each of which is directly bonded to a silicon atom, (C-1) a spherical alumina filler that has an average particle diameter of more than 100 μm but not more than 150 μm, (C-5) an amorphous alumina filler that has an average particle diameter of more than 0.85 μm but not more than 5 μm, and (D) a platinum group metal-based curing catalyst, respectively in specific amounts. The present invention provides: a thermally conductive silicone composition which has excellent compressibility, insulation properties, thermal conductivity and processability, and which is suitable for use as a thermally conductive resin molded body that is arranged between a heat generating component and a heat dissipation component for the purpose of heat dissipation; a method for producing this thermally conductive silicone composition; and a thermally conductive silicone cured product.

Description

Thermally conductive silicone composition and its manufacturing method, and thermally conductive silicone cured product

INDUSTRIAL APPLICABILITY The present invention has a heat conductive silicone composition useful as a heat transfer material interposed at an interface between a heat interface of a heat generating electronic part and a heat radiating member such as a heat sink or a circuit board, particularly for cooling an electronic part by heat conduction. The present invention relates to a product, a method for producing the product, and a heat conductive silicone cured product.

CPUs used in electronic devices such as personal computers, digital video discs, and mobile phones, and LSI chips such as driver ICs and memories have become large in quantity due to higher performance, higher speed, smaller size, and higher integration. Heat is generated, and the temperature rise of the chip due to the heat causes malfunction and destruction of the chip. Therefore, many heat dissipation methods and heat dissipation members used for suppressing the temperature rise of the chip during operation have been proposed.

Conventionally, in electronic devices and the like, a heat sink using a metal plate having high thermal conductivity such as aluminum or copper has been used in order to suppress a temperature rise of a chip during operation. This heat sink conducts the heat generated by the chip and releases the heat from the surface due to the temperature difference from the outside air.
In order to efficiently transfer the heat generated from the chip to the heat sink, it is necessary to attach the heat sink to the chip, but due to the difference in height of each chip and the tolerance due to the assembly process, a flexible sheet or grease should be used. It is interposed between the chip and the heat sink, and heat conduction from the chip to the heat sink is realized through this sheet or grease.

The sheet is superior in handleability to grease, and a heat conductive sheet (heat conductive silicone rubber sheet) formed of heat conductive silicone rubber or the like is used in various fields.
Patent Document 1 contains 100 to 800 parts by mass of at least one metal oxide selected from beryllium oxide, aluminum oxide, hydrated aluminum oxide, magnesium oxide, and zinc oxide in 100 parts by mass of synthetic rubber such as silicone rubber. The insulating composition is disclosed.

On the other hand, as electronic devices such as personal computers, word processors, and CD-ROM drives have become highly integrated, and the amount of heat generated by integrated circuit elements such as LSIs and CPUs in the devices has increased, conventional cooling methods may not be sufficient. is there. In particular, in the case of a portable notebook personal computer, a large heat sink or cooling fan cannot be attached because the space inside the device is small. Further, in these devices, integrated circuit elements are mounted on a printed circuit board, and glass-reinforced epoxy resin or polyimide resin having poor thermal conductivity is used as the material of the substrate, so that the heat-dissipating insulating sheet is used as in the conventional case. The heat cannot be released to the substrate.

Therefore, a method is used in which a natural cooling type or forced cooling type heat radiating component is installed in the vicinity of the integrated circuit element, and the heat generated by the element is transferred to the heat radiating component. If the element and the heat radiating component are brought into direct contact with each other by this method, heat transfer will be poor due to the unevenness of the surface, and even if the element is attached via the heat radiating insulation sheet, the flexibility of the heat radiating insulation sheet will be slightly inferior. Stress is applied between the substrate and the substrate, which may cause damage.
In addition, if it is attempted to attach a heat radiating component to each circuit element, an extra space is required and it becomes difficult to miniaturize the device. Therefore, a method of cooling by combining several elements into one heat radiating component may be adopted. ..
In particular, the BGA type CPU used in a notebook personal computer has a lower height than other elements and a large amount of heat generation, so it is necessary to fully consider the cooling method.

Therefore, a high thermal conductive material having a low hardness that can fill various gaps caused by different heights for each element is required. To solve such problems, a heat conductive sheet having excellent thermal conductivity, flexibility, and being able to cope with various gaps is required.
In this case, Patent Document 2 describes a sheet formed by mixing a heat conductive material such as a metal oxide with a silicone resin, and is soft and easily deformed on a silicone resin layer having strength necessary for handling. A sheet on which a silicone layer is laminated is disclosed. Further, Patent Document 3 describes the thermal conductivity of a combination of a silicone rubber layer containing a thermally conductive filler and having an Asker C hardness of 5 to 50 and a porous reinforcing material layer having holes having a diameter of 0.3 mm or more. The composite sheet is disclosed. Patent Document 4 discloses a sheet in which the skeletal lattice surface of a flexible three-dimensional network or foam is coated with a thermally conductive silicone rubber. Patent Document 5 contains a reinforcing sheet or cloth, and has adhesiveness on at least one surface, and has an Asker C hardness of 5 to 50. A heat conductive composite silicone having a thickness of 0.4 mm or less. The sheet is disclosed. Patent Document 6 describes a heat dissipation spacer containing an addition reaction type liquid silicone rubber and a heat conductive insulating ceramic powder, and having an Asker C hardness of 25 or less and a thermal resistance of 3.0 ° C / W or less of the cured product. It is disclosed.

Since these heat conductive silicone cured products are often required to have insulating properties, aluminum oxide (alumina) is mainly used as a heat conductive filler in the range of thermal conductivity of 0.5 to 6 W / mK. Is often done. In general, amorphous alumina has a higher effect of improving thermal conductivity than spherical alumina, but has a drawback that the filling property with respect to silicone is poor, the material viscosity is increased by filling, and the processability is deteriorated. .. In addition, alumina has a Mohs hardness of 9 which is very hard so that it can be used as an abrasive. Therefore, in particular, the thermally conductive silicone composition using amorphous alumina having a particle size of 10 μm or more has a problem that the inner wall of the reaction kettle and the stirring blade are scraped if a share is applied during production. Then, the components of the reaction kettle and the stirring blade are mixed in the heat conductive silicone composition, and the insulating property of the heat conductive silicone composition and the cured product using the same is lowered. In addition, the clearance between the reaction kettle and the stirring blade is widened, the stirring efficiency is lowered, and a certain quality cannot be obtained even if the product is manufactured under the same conditions. In addition, there is a problem that parts need to be replaced frequently in order to prevent it.

In order to solve this problem, there is a method of using only spherical alumina powder, but in order to achieve high thermal conductivity, it is necessary to fill a large amount as compared with amorphous alumina, and the viscosity of the composition increases. Workability deteriorates. Further, since the abundance of silicone in the composition and the cured product thereof is relatively reduced, the hardness is increased and the compressibility becomes inferior.
Further, in order to increase the thermal conductivity, there is generally a method of using a thermally conductive filler having a high thermal conductivity, for example, a thermally conductive filler such as aluminum nitride or boron nitride, but the cost is high. There was a problem that processing was also difficult.

JP-A-47-32400 Japanese Unexamined Patent Publication No. 2-196453 Japanese Unexamined Patent Publication No. 7-266356 Japanese Unexamined Patent Publication No. 8-238707 Japanese Unexamined Patent Publication No. 9-1738 Japanese Unexamined Patent Publication No. 9-296114

The present invention has been made in view of the above circumstances, and is excellent in compressibility, insulation, thermal conductivity, and workability, and particularly has a thermal conductivity of 6.5 W / mK or more, for example, a heat-generating component in an electronic device. It is an object of the present invention to provide a thermally conductive silicone composition and a cured product thereof, which are installed between the heat-dissipating component and a thermally conductive resin molded body which is used for heat dissipation.

In order to achieve the above problems, in the present invention, the following (A) to (D) components (A) are organopolysiloxanes having at least two alkenyl groups in one molecule: 100 parts by mass,
(B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to the silicon atom: The number of moles of the hydrogen atom directly bonded to the silicon atom is 0.1 of the number of moles of the alkenyl group derived from the component (A). ~ 5.0 times the amount,
(C) Thermally conductive filler composed of the following (C-1) to (C-6): 7,500 to 11,500 parts by mass,
(C-1) 1,400 to 5,500 parts by mass of a spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less.
(C-2) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 65 μm and 100 μm or less.
(C-3) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 35 μm and 65 μm or less.
(C-4) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 5 μm and 30 μm or less.
(C-5) 1,000 to 4,500 parts by mass of amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less.
(C-6) 0 to 450 parts by mass of a spherical alumina filler having an average particle size of more than 0.2 μm and 0.85 μm or less.
(D) Platinum group metal-based curing catalyst: 0.1 to 2,000 ppm in terms of platinum group element mass with respect to the component (A).
Provided is a thermally conductive silicone composition containing.

This thermally conductive silicone composition is excellent in compressibility, insulation, thermal conductivity, and processability, and gives a thermally conductive silicone cured product having a thermal conductivity of 6.5 W / mK or more.

This thermally conductive silicone composition further contains, as a component (F).
(F-1) The following general formula (1)
R ¹ _a R ² _b Si (OR ³ ) _4-ab (1)
(In the formula, R ¹ is an independently alkyl group having 6 to 15 carbon atoms, R ² is an independently unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and R ³ is independent. It is an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, and a + b is an integer of 1 to 3.)
The alkoxysilane compound represented by (F-2) and the following general formula (2)

(In the formula, R ⁴ is independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100.)
At least one selected from the group consisting of dimethylpolysiloxane in which one end of the molecular chain represented by is sealed with a trialkoxysilyl group: 0.01 to 300 parts by mass with respect to 100 parts by mass of the component (A). It is preferable that it is one.

When this thermally conductive silicone composition contains at least one selected from the group consisting of the alkoxysilane compound and the dimethylpolysiloxane, the (C) thermally conductive filler is added to the (A) organopolysiloxane. It can be uniformly dispersed.

This thermally conductive silicone composition further contains the following general formula (3) as the component (G).

(In the formula, R ⁵ is an independently monovalent hydrocarbon group having 1 to 12 carbon atoms and does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000.)
It is preferable that the organopolysiloxane having a kinematic viscosity at 23 ° C. of 10 to 100,000 mm ² / s is contained in an amount of 0.1 to 100 parts by mass with respect to 100 parts by mass of the component (A).

When this thermally conductive silicone composition contains an organopolysiloxane represented by the above general formula (3), the flexibility of the cured product of the thermally conductive silicone, which is a cured product of this composition, is further improved.

The absolute viscosity of this thermally conductive silicone composition at 23 ° C. is preferably 800 Pa · s or less.
When the absolute viscosity of this thermally conductive silicone composition is as described above, the moldability of this composition becomes higher.

Further, the present invention provides a cured product of the heat conductive silicone composition, which is a cured product of the heat conductive silicone composition.
This thermally conductive silicone cured product is excellent in compressibility, insulation, thermal conductivity, and processability, and has a thermal conductivity of 6.5 W / mK or more.

The thermal conductivity of this thermally conductive silicone cured product is preferably 6.5 W / mK or more.
When the thermal conductivity of this thermally conductive silicone cured product is as described above, the cured product has higher thermal conductivity.

The hardness of this thermally conductive silicone cured product is preferably 60 or less on an Asker C hardness tester.
When the hardness of the heat conductive silicone cured product is as described above, the cured product is deformed to follow the shape of the heat radiated body and exhibits better heat radiating characteristics without applying stress to the heat radiated body. It becomes a thing.

The dielectric breakdown voltage of this thermally conductive silicone cured product is preferably 10 kV / mm or more.
When the dielectric breakdown voltage of the heat conductive silicone cured product is as described above, the cured product can secure more stable insulation during use.

Further, the present invention provides a method for producing the thermally conductive silicone composition, which comprises a step of stirring the components (A), (C) and (F) while heating them.
By this method for producing a thermally conductive silicone composition, it is possible to produce a thermally conductive silicone composition that gives a cured product in which the generation of bubbles on the surface is reduced.

The thermally conductive silicone composition of the present invention comprises an amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less, and a spherical alumina filler having an average particle size of more than 0.2 μm and 100 μm or less, if necessary. By using a spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less in a specific blending amount, the large particle size spherical alumina filler compensates for the drawbacks of the amorphous alumina filler having a small particle size, and the large particles are used. By compensating for the drawbacks of the radial spherical alumina filler with the amorphous alumina filler with a small particle size, it is excellent in compressibility, insulation, thermal conductivity, and workability, and in particular, heat having a thermal conductivity of 6.5 W / mK or more. It is possible to provide a thermally conductive silicone composition that provides a cured conductive silicone product.
Further, in the step of producing the above composition, the bubbles generated on the surface of the cured product after molding can be reduced by stirring while heating.

As described above, heat conduction which is excellent in compressibility, insulation, heat conductivity, and workability, and is preferably used for a heat conductive resin molded body which is installed between heat generating parts and heat radiating parts and used for heat radiating. Development of a sex silicone composition and a cured product thereof has been required.

As a result of diligent studies to achieve the above object, the present inventor has made an amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less, and if necessary, an average particle size of more than 0.2 μm. It has been found that the above problem can be solved by using a spherical alumina filler of 100 μm or less and a spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less in a specific blending amount. That is, by blending a spherical alumina filler having a specific surface area of more than 100 μm and 150 μm or less, it is possible to effectively improve the thermal conductivity, and the silicone composition having low viscosity and excellent workability and The cured product can be provided.
Further, by using an amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less and, if necessary, a spherical alumina filler having an average particle size of more than 0.2 μm and 100 μm or less, the composition is formed. The fluidity is improved and the workability is improved. Further, since spherical alumina filler is used as the particles having a particle size of 10 μm or more and amorphous alumina filler having a large polishing effect is not used, wear of the reaction kettle and the stirring blade is suppressed, and the insulating property is improved.

In other words, the defects of the amorphous alumina filler with a small particle size are compensated for by the large particle size spherical alumina filler, and the defects of the large particle size spherical alumina filler are compensated for by the amorphous alumina filler with a small particle size. We have found that it is possible to provide a low-cost thermally conductive silicone composition having excellent thermal conductivity and workability, particularly a thermal conductivity of 6.5 W / mK or more, and a cured product thereof, and have achieved the present invention. It was.

That is, in the present invention, an organopolysiloxane having at least two alkenyl groups in one molecule of the following components (A) to (D) (A): 100 parts by mass,
(B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to the silicon atom: The number of moles of the hydrogen atom directly bonded to the silicon atom is 0.1 of the number of moles of the alkenyl group derived from the component (A). ~ 5.0 times the amount,
(C) Thermally conductive filler composed of the following (C-1) to (C-6): 7,500 to 11,500 parts by mass,
(C-1) 1,400 to 5,500 parts by mass of a spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less.
(C-2) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 65 μm and 100 μm or less.
(C-3) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 35 μm and 65 μm or less.
(C-4) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 5 μm and 30 μm or less.
(C-5) 1,000 to 4,500 parts by mass of amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less.
(C-6) 0 to 450 parts by mass of a spherical alumina filler having an average particle size of more than 0.2 μm and 0.85 μm or less.
(D) Platinum group metal-based curing catalyst: 0.1 to 2,000 ppm in terms of platinum group element mass with respect to the component (A).
It is a heat conductive silicone composition containing.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.
The thermally conductive silicone composition of the present invention comprises (A) an alkenyl group-containing organopolysiloxane, (B) an organohydrogenpolysiloxane, (C) a thermally conductive filler, and (D) a platinum group metal-based curing catalyst. contains.

[Organopolysiloxane containing alkenyl group]
The alkenyl group-containing organopolysiloxane as the component (A) is an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms in one molecule, and is the main agent of the thermally conductive silicone cured product of the present invention. Is. Normally, the main chain portion basically consists of repeating diorganosiloxane units, but this may include a branched structure as part of the molecular structure, or it may be cyclic. Although it may be a body, a linear diorganopolysiloxane is preferable from the viewpoint of physical properties such as the mechanical strength of the cured product.

The functional group other than the alkenyl group bonded to the silicon atom is an unsubstituted or substituted monovalent hydrocarbon group, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tert-butyl. Alkyl group such as group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, cycloalkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group, phenyl group, trill group. , Aryl groups such as xylyl group, naphthyl group and biphenylyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group and methylbenzyl group, and some hydrogen atoms having carbon atoms bonded to these groups. Alternatively, a group entirely substituted with a halogen atom such as fluorine, chlorine, bromine, a cyano group, etc., for example, a chloromethyl group, a 2-bromoethyl group, a 3-chloropropyl group, a 3,3,3-trifluoropropyl group, Examples thereof include a chlorophenyl group, a fluorophenyl group, a cyanoethyl group, a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group. Typical ones have 1 to 10 carbon atoms, and particularly typical ones have 1 to 6 carbon atoms, preferably methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3 , 3,3-Trifluoropropyl group, cyanoethyl group and other unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms, and phenyl group, chlorophenyl group, fluorophenyl group and other unsubstituted or substituted phenyl groups. .. Further, the functional groups other than the alkenyl group bonded to the silicon atom are not limited to being all the same.

Examples of the alkenyl group include those having a normal carbon atom number of about 2 to 8, such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group, and among them, vinyl. A lower alkenyl group such as a group or an allyl group is preferable, and a vinyl group is more preferable. It is preferable that two or more alkenyl groups are present in the molecule, but it is preferable that the alkenyl group is present only at the silicon atom at the end of the molecular chain in order to improve the flexibility of the obtained cured product.

The kinematic viscosity of this organopolysiloxane at 23 ° C. is usually preferably in the range of 10 to 100,000 mm ² / s, more preferably 500 to 50,000 mm ² / s. When the viscosity is 10 mm ² / s or more, the storage stability of the obtained composition is improved, and when the viscosity is 100,000 mm ² / s or less, the extensibility of the obtained composition is high. The kinematic viscosity is a value when an Ostwald viscometer is used (hereinafter, the same applies).
The organopolysiloxane of the component (A) may be used alone or in combination of two or more having different viscosities.

[Organohydrogenpolysiloxane]
The organohydrogenpolysiloxane of the component (B) is an organohydrogenpolysiloxane having an average of 2 or more hydrogen atoms (Si—H groups) directly bonded to 2 to 100 silicon atoms in one molecule. It is a component that acts as a cross-linking agent for the component (A). That is, the Si—H group in the component (B) and the alkenyl group in the component (A) are added and crosslinked by a hydrosilylation reaction promoted by a platinum group metal-based curing catalyst of the component (D) described later. A three-dimensional network structure having a structure is given. If the number of Si—H groups is less than 2, it will not be cured.

As the organohydrogenpolysiloxane, those represented by the following average structural formula (4) are used, but the organohydrogenpolysiloxane is not limited thereto.

(In the formula, R ⁶ is an unsubstituted or substituted monovalent hydrocarbon group independently containing no hydrogen atom or an aliphatic unsaturated bond, but at least two, preferably 2 to 10 hydrogen atoms. e is an integer of 1 or more, preferably an integer of 10 to 200.)

In the formula (4), the monovalent hydrocarbon radical unsubstituted or substituted free of aliphatic unsaturation other than a hydrogen atom of R ^6, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group , Isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group and other alkyl groups, cyclopentyl group, cyclohexyl group, cycloheptyl group and other cycloalkyl groups. Aryl groups such as groups, phenyl groups, trill groups, xsilyl groups, naphthyl groups and biphenylyl groups, aralkyl groups such as benzyl groups, phenylethyl groups, phenylpropyl groups and methylbenzyl groups, and carbon atoms of these groups are bonded. A group in which a part or all of the hydrogen atoms are substituted with a halogen atom such as fluorine, chlorine or bromine or a cyano group, for example, a chloromethyl group, a 2-bromoethyl group, a 3-chloropropyl group, 3,3 Examples thereof include 3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group. Typical ones have 1 to 10 carbon atoms, and particularly typical ones have 1 to 6 carbon atoms, preferably methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3 , 3,3-Trifluoropropyl group, cyanoethyl group and other unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms, and phenyl group, chlorophenyl group, fluorophenyl group and other unsubstituted or substituted phenyl groups. .. Further, R ⁶ does not limit that all are the same.

The amount of the component (B) added is such that the Si—H group derived from the component (B) is 0.1 to 5.0 mol with respect to 1 mol of the alkenyl group derived from the component (A), preferably 0.3. The amount is up to 2.0 mol, more preferably 0.5 to 1.0 mol. If the amount of Si—H groups derived from the component (B) is less than 0.1 mol with respect to 1 mol of the alkenyl group derived from the component (A), the thermally conductive silicone composition does not cure, or the strength of the cured product is high. Insufficient, it may not be possible to maintain the shape of the molded product and handle it. If it exceeds 5.0 mol, the cured product loses its flexibility and the cured product becomes brittle.

[Thermal conductivity filler]
The thermally conductive filler which is the component (C) is composed of the following components (C-1) to (C-6).
(C-1) A spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less.
(C-2) Spherical alumina filler having an average particle size of more than 65 μm and 100 μm or less.
(C-3) Spherical alumina filler having an average particle size of more than 35 μm and 65 μm or less,
(C-4) Spherical alumina filler having an average particle size of more than 5 μm and 30 μm or less.
(C-5) Amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less.
(C-6) Spherical alumina filler having an average particle size of more than 0.2 μm and 0.85 μm or less In the present invention, the average particle size is, for example, Microtrac, which is a particle size analyzer manufactured by Nikkiso Co., Ltd. It is a value of the cumulative average particle size (median diameter) based on the volume measured by MT3300EX.

The spherical alumina filler of the component (C-1) can significantly improve the thermal conductivity. The average particle size of the spherical alumina filler of the component (C-1) is more than 100 μm and 150 μm or less, preferably 105 to 140 μm. When the average particle size of the spherical alumina filler of the component (C-1) is larger than 150 μm, the reaction kettle and the stirring blade are significantly worn, and the insulating property of the composition is lowered. As the spherical alumina filler of the component (C-1), one kind or two or more kinds may be used in combination.

The spherical alumina fillers of the components (C-2) to (C-4) improve the thermal conductivity of the composition and suppress the contact between the amorphous alumina filler of the component (C-5) and the reaction kettle or the stirring blade. It provides a barrier effect that suppresses wear. Regarding the average particle size, the component (C-2) is more than 65 μm and 100 μm or less, preferably 70 to 95 μm, and the component (C-3) is more than 35 μm and 65 μm or less, 40 to 60 μm. The component (C-4) is preferably more than 5 μm and 30 μm or less, and preferably 7 to 25 μm. As the spherical alumina filler of the components (C-2) to (C-4), one kind or two or more kinds may be used in combination.

The amorphous alumina filler of the component (C-5) also plays a role of improving the thermal conductivity of the composition, but its main role is to adjust the viscosity of the composition, improve the smoothness, and improve the filling property. The average particle size of the component (C-5) is more than 0.85 μm and 5 μm or less, preferably 0.9 to 4 μm for the above-mentioned characteristic expression.

The main role of the spherical alumina filler of the component (C-6) is to adjust the viscosity of the composition, improve the smoothness, and improve the filling property. The average particle size of the component (C-6) is more than 0.2 μm and 0.85 μm or less. When the average particle size is less than 0.2 μm, the viscosity of the composition becomes remarkably large, and the moldability is greatly impaired.

The blending amount of the component (C-1) is 1,400 to 5,500 parts by mass, preferably 1,800 to 4,000 parts by mass with respect to 100 parts by mass of the component (A). If the amount of the component (C-1) is too small, it is difficult to improve the thermal conductivity, and if it is too large, the reaction kettle and the stirring blade are significantly worn, and the insulating property of the composition is lowered.

The blending amount of the components (C-2) to (C-4) is 0 to 2,200 parts by mass, preferably 900 to 1,600 parts by mass, respectively, with respect to 100 parts by mass of the component (A). .. When each of the components (C-2) to (C-4) is blended, the thermal conductivity of the cured product is improved, and when the amount is too large, the fluidity of the composition is lost and the moldability is impaired.

The blending amount of the component (C-5) is 1,000 to 4,000 parts by mass, preferably 2,000 to 2,800 parts by mass with respect to 100 parts by mass of the component (A). If the amount of the component (C-5) is too small, the fluidity of the composition is lost and the moldability is impaired. It is difficult to improve the thermal conductivity of the cured product even if the component (C-5) is blended in an amount of more than 4,000 parts by mass.

The blending amount of the component (C-6) is 0 to 450 parts by mass, preferably 250 to 400 parts by mass with respect to 100 parts by mass of the component (A). When the component (C-6) is blended, the effect of improving the fluidity of the composition is exhibited.

Further, the blending amount of the component (C) (that is, the total blending amount of the components (C-1) to (C-6) above) is 7,500 to 11,500 mass with respect to 100 parts by mass of the component (A). It is a part, preferably 7,600 to 9,000 parts by mass. If the blending amount is less than 7,500 parts by mass, the thermal conductivity of the obtained cured product deteriorates, and if it exceeds 11,500 parts by mass, the fluidity of the composition is lost and the moldability becomes poor. It is impaired.

By using the component (C) in the above-mentioned blending amount, the above-mentioned effect of the present invention can be achieved more advantageously and surely.

[Platinum group metal-based curing catalyst]
The platinum group metal-based curing catalyst of the component (D) is a catalyst for promoting the addition reaction of the alkenyl group derived from the component (A) and the Si—H group derived from the component (B), and is used in the hydrosilylation reaction. Examples of the catalyst to be used include well-known catalysts. Specific examples thereof include platinum (including platinum black), rhodium, palladium and other platinum group metals alone, H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaH PtCl ₆ · nH ₂ O. , KHPtCl ₆・ nH ₂ O, Na ₂ PtCl ₆・ nH ₂ O, K ₂ PtCl ₄・ nH ₂ O, PtCl ₄・ nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄・ nH ₂ O (However, in the formula, n is an integer of 0 to 6, preferably 0 or 6) and the like platinum chloride, platinum chloride and platinum chloride, alcohol-modified platinum chloride (US Pat. No. 3,220,972). (See), Platinum Chloropate and Olefin Complex (see US Pat. Nos. 3,159,601, 3,159,662, 3,775,452), Platinum Black , Platinum group metal such as palladium supported on a carrier such as alumina, silica, carbon, rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkinson catalyst), platinum chloride, platinum chloride acid or platinum chloride acid. Examples thereof include a complex of a salt and a vinyl group-containing siloxane, particularly a vinyl group-containing cyclic siloxane.

The amount of the component (D) used is 0.1 to 2,000 ppm, preferably 50 to 1000 ppm, in terms of mass of the platinum group metal element with respect to the component (A).

[Addition reaction control agent]
In the heat conductive silicone composition of the present invention, an addition reaction control agent can be further used as the component (E). As the addition reaction control agent, all known addition reaction control agents used in ordinary addition reaction curable silicone compositions can be used. Examples thereof include acetylene compounds such as 1-ethynyl-1-hexanol, 3-butin-1-ol, and ethynylmethyldencarbinol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds.

The amount used when the component (E) is blended is preferably 0.01 to 1 part by mass, more preferably about 0.1 to 0.8 parts by mass with respect to 100 parts by mass of the component (A). When the blending amount of the component (E) is not more than the upper limit, the curing reaction proceeds and the molding efficiency is not impaired.

[Surface treatment agent]
In the heat conductive silicone composition of the present invention, the heat conductive filler which is the component (C) is hydrophobized at the time of preparing the composition to improve the wettability with the organopolysiloxane which is the component (A). The surface treatment agent of the component (F) can be blended for the purpose of uniformly dispersing the thermally conductive filler as the component (C) in the matrix composed of the component (A). As the component (F), the components (F-1) and (F-2) shown below are particularly preferable.

The component (F-1) is an alkoxysilane compound represented by the following general formula (1).
R ¹ _a R ² _b Si (OR ³ ) _4-ab (1)
(In the formula, R ¹ is an independently alkyl group having 6 to 15 carbon atoms, R ² is an independently unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and R ³ is independent. It is an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, and a + b is an integer of 1 to 3.)

In the above general formula (1), examples of the alkyl group represented by R ¹ include a hexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, a tetradecyl group and the like. When the number of carbon atoms of the alkyl group represented by R ¹ satisfies the range of 6 to 15, the wettability of the component (A) is sufficiently improved, the handleability is good, and the low temperature characteristics of the composition are good. Become.

The unsubstituted or substituted monovalent hydrocarbon group represented by R ^2, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, butyl group, isobutyl group, tert- butyl group, a pentyl group, a neopentyl group, Alkyl group such as hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, cycloalkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group, phenyl group, trill group, xsilyl group, naphthyl group, biphenylyl Aluryl groups such as groups, benzyl groups, phenylethyl groups, phenylpropyl groups, aralkyl groups such as methylbenzyl groups, and some or all of the hydrogen atoms to which the carbon atoms of these groups are bonded are fluorine, chlorine, bromine. Group substituted with halogen atom, cyano group, etc., such as chloromethyl group, 2-bromoethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl Groups, 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups and the like are mentioned, and typical ones have 1 to 10 carbon atoms, and particularly typical ones have carbon atoms. The number is 1 to 6, preferably 1 to 3 carbon atoms such as methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3,3,3-trifluoropropyl group and cyanoethyl group. Examples thereof include an unsubstituted or substituted alkyl group and an unsubstituted or substituted phenyl group such as a phenyl group, a chlorophenyl group and a fluorophenyl group. Examples of R ³ include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group and the like.

The component (F-2) is a dimethylpolysiloxane in which one end of the molecular chain represented by the following general formula (2) is sealed with a trialkoxysilyl group.

(In the formula, R ⁴ is an independently alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100, preferably 5 to 70, and more preferably 10 to 50.)

As the surface treatment agent for the component (F), either one of the component (F-1) and the component (F-2) may be blended in combination.
When the component (F) is blended, the blending amount is preferably 0.01 to 300 parts by mass, more preferably 0.1 to 200 parts by mass with respect to 100 parts by mass of the component (A). .. If the blending amount of the component (F) is not more than the above upper limit, oil separation is not induced.

[Organopolysiloxane]
The heat conductive silicone composition of the present invention contains the following general formula (3) as a component (G) for the purpose of imparting characteristics such as a viscosity modifier of the heat conductive silicone composition.

(In the formula, R ⁵ is an independently monovalent hydrocarbon group having 1 to 12 carbon atoms and does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000.)
Organopolysiloxane having a kinematic viscosity of 10 to 100,000 mm ² / s at 23 ° C. represented by ² can be added. The component (G) may be used alone or in combination of two or more.

In the general formula (3), R ⁵ is a monovalent hydrocarbon group containing no aliphatic unsaturated bonds unsubstituted or substituted having 1 to 12 carbon atoms independently. The R ^5, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, butyl group, isobutyl group, tert- butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group , Alkyl group such as dodecyl group, cycloalkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group, aryl group such as phenyl group, trill group, xsilyl group, naphthyl group, biphenylyl group, benzyl group, phenylethyl group, phenylpropi An aralkyl group such as a ru group or a methylbenzyl group, and a group in which a part or all of the hydrogen atom to which the carbon atom of these groups is bonded is substituted with a halogen atom such as fluorine, chlorine or bromine or a cyano group. For example, chloromethyl group, 2-bromoethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,5,5,5. Examples thereof include 6,6,6-nonafluorohexyl groups, and typical ones have 1 to 10 carbon atoms, and particularly typical ones have 1 to 6 carbon atoms, preferably methyl groups. , Ethyl group, propyl group, chloromethyl group, bromoethyl group, 3,3,3-trifluoropropyl group, cyanoethyl group and other unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms, and phenyl group and chlorophenyl group. , Fluorophenyl group and the like, but not substituted or substituted phenyl group, but methyl group and phenyl group are more preferable.
From the viewpoint of the required viscosity, d is preferably an integer of 5 to 2,000, and more preferably an integer of 10 to 1,000.

Moreover, kinematic viscosity at 23 ° C. of component (G) is preferably 10 ~ 100,000mm ² / s, more preferably 100 ~ 10,000mm ² / s. When the kinematic viscosity is 10 mm ² / s or more, the obtained thermally conductive silicone cured product does not generate oil bleed. When the kinematic viscosity is 100,000 mm ² / s or less, the flexibility of the obtained thermally conductive silicone cured product is sufficient.

When the component (G) is blended into the thermally conductive silicone composition of the present invention, the blending amount is not particularly limited as long as the desired effect can be obtained, but with respect to 100 parts by mass of the component (A). It is preferably 0.1 to 100 parts by mass, and more preferably 1 to 50 parts by mass. When the blending amount is in this range, it is easy to maintain good fluidity and workability in the heat conductive silicone composition before curing, and the heat conductive filler of the component (C) is filled in the composition. Is easy.

[Other ingredients]
Other components may be further added to the thermally conductive silicone composition of the present invention. For example, any component such as a heat resistance improver such as iron oxide and cerium oxide; a viscosity modifier such as silica; a colorant; and a mold release agent can be blended.

[Viscosity of Thermally Conductive Silicone Composition]
The absolute viscosity of the thermally conductive silicone composition of the present invention is preferably 800 Pa · s or less, more preferably 700 Pa · s or less at 23 ° C. When the viscosity is 800 Pa · s or less, the moldability of the composition is not impaired. The lower limit is not particularly limited, but the absolute viscosity can be, for example, 100 Pa · s or more. In the present invention, this viscosity is based on the measurement by a B-type viscometer.

[Preparation of thermally conductive silicone composition]
The thermally conductive silicone composition of the present invention can be prepared by uniformly mixing each of the above-mentioned components according to a conventional method. When the component (F) is used, it is preferable to stir the components (A), (C) and (F) while heating. The heating temperature is preferably 50 to 200 ° C, more preferably 80 to 170 ° C.

[Manufacturing method of thermally conductive silicone cured product]
The curing conditions for molding the thermally conductive silicone composition may be the same as those of the known addition reaction-curable silicone rubber composition. For example, it is sufficiently cured at room temperature, but may be heated if necessary. It is preferable to carry out additional curing at 100 to 120 ° C. for 8 to 12 minutes. Such a cured silicone product of the present invention has excellent thermal conductivity.

[Thermal conductivity of cured silicone silicone]
The thermal conductivity of the heat conductive silicone cured product of the present invention is preferably 6.5 W / mK or more, and more preferably 7.0 W / mK or more, as measured by the hot disk method at 23 ° C. preferable. The upper limit is not particularly limited, but the thermal conductivity can be, for example, 8.0 W / mK or less.

[Hardness of thermally conductive silicone cured product]
The hardness of the heat conductive silicone cured product in the present invention is preferably 60 or less, more preferably 40 or less, still more preferably 30 or less, and 5 or more, as measured by an Asker C hardness tester at 23 ° C. Is preferable. When the hardness is 60 or less, it is deformed to follow the shape of the heat-dissipated body, and good heat-dissipating characteristics can be exhibited without applying stress to the heat-dissipated body. In addition, such hardness can be adjusted by changing the ratio of the component (A) and the component (B) and adjusting the cross-linking density.

[Insulation breakdown voltage of thermally conductive silicone cured product]
The breakdown voltage of the heat conductive silicone cured product of the present invention is preferably 10 kV or more, more preferably 13 kV or more, as a measured value when the breakdown voltage of a 1 mm thick molded product is measured in accordance with JIS K 6249. is there. In the case of a sheet having a breakdown voltage of 10 kV / mm or more, stable insulation can be ensured during use. The upper limit is not particularly limited, but the dielectric breakdown voltage can be, for example, 25 kV / mm or less. The dielectric breakdown voltage can be adjusted by adjusting the type and purity of the filler.

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 kinematic viscosity was measured at 23 ° C. with an Ostwald viscometer. The average particle size is a volume-based cumulative average particle size (median diameter) measured by a microtrack MT3300EX, which is a particle size analyzer manufactured by Nikkiso Co., Ltd.

The components (A) to (F) used in the following Examples and Comparative Examples are shown below.
Component (A) component: The following two types of organopolysiloxane (A-1) component: Organopolysiloxane (A-2) component having a kinematic viscosity of 400 mm ² / s represented by the following formula (5): the following formula (5) Organopolysiloxane with kinematic viscosity of 30,000 mm ² / s

(In the formula, X is a vinyl group and f is a number that gives the above viscosity.)
Component (B): Organohydrogenpolysiloxane represented by the following formula (6)

(In the formula, g is 27 and h is 3.)

Component (C): Spherical alumina having the following average particle size, amorphous alumina (C-1) Spherical alumina having an average particle size of 124.2 μm (C-2) Spherical alumina having an average particle size of 88.6 μm (C-3) Spherical alumina with an average particle size of 48.7 μm (C-4) Spherical alumina with an average particle size of 16.7 μm (C-5) Atypical alumina with an average particle size of 2.4 μm (C-6) ) Spherical alumina with an average particle size of 0.8 μm

Component (D): 5-Mass% 2-ethylhexanol chloride solution (E) Component: Ethynylmethylidenecarbinol as an addition reaction control agent

Component (F): Didimethylpolysiloxane having an average degree of polymerization of 30 represented by the following formula (7) and having one end sealed with a trimethoxysilyl group.

Component (G): Didimethylpolysiloxane represented by the following formula (8) as a plasticizer

(In the formula, j is 80.)

<Examples 1 to 4, Comparative Examples 1 to 2>
In Examples 1 to 4 and Comparative Examples 1 and 2, a composition was prepared as follows using the predetermined amounts of the above components (A) to (G) shown in Table 1 below, and the composition was prepared according to the following method. The viscosity was measured. The composition was molded and cured, and the thermal conductivity, hardness, breakdown voltage, specific gravity and bubbles on the surface of the cured product of the obtained cured product were measured or observed according to the following methods. The results are shown in Table 1.

[Preparation of composition]
The components (A), (C), and (F) were added in the predetermined blending amounts shown in Examples 1 to 4 and Comparative Examples 1 and 2 in Table 1 below, kneaded with a planetary mixer for 30 minutes, and then at 145 ° C. Kneading was performed with or without heating for 60 minutes. After sufficiently cooling, the components (D) and (G) are added thereto in predetermined amounts shown in Examples 1 to 4 and Comparative Examples 1 and 2 in Table 1 below to further promote mold release from the separator. An effective amount of KF-54, a phenyl-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd., was added as a release agent, and the mixture was kneaded for 30 minutes.
The components (B) and (E) were further added thereto in the predetermined blending amounts shown in Examples 1 to 4 and Comparative Examples 1 and 2 in Table 1 below, and kneaded for 30 minutes to obtain a composition.

[viscosity]
The viscosities of the compositions obtained in Examples 1 to 4 were measured with a B-type viscometer in an environment of 23 ° C.

[Thermal conductivity]
The compositions obtained in Examples 1 to 4 were poured into a mold of 60 mm × 60 mm × 6 mm and cured into a 6 mm thick sheet at 120 ° C. for 10 minutes using a press molding machine, and the sheet was cured into a sheet of 6 mm thickness. Using the sheet, the thermal conductivity of the sheet was measured with a thermal conductivity meter (trade name: TPS-2500S, manufactured by Kyoto Denshi Kogyo Co., Ltd.).

[hardness]
The compositions obtained in Examples 1 to 4 were cured into a sheet having a thickness of 6 mm in the same manner as described above, and two sheets thereof were stacked and the hardness of the sheet was measured with an Asker C hardness tester.

[Dielectric breakdown voltage]
The compositions obtained in Examples 1 to 4 were poured into a mold of 60 mm × 60 mm × 6 mm and cured into a 1 mm thick sheet at 120 ° C. for 10 minutes using a press molding machine to obtain JIS K 6249. The breakdown voltage was measured in accordance with this.

[specific gravity]
The compositions obtained in Examples 1 to 4 were poured into a mold of 60 mm × 60 mm × 6 mm and cured into a 1 mm thick sheet at 120 ° C. for 10 minutes using a press molding machine, and the specific gravity of the cured product was obtained. Was measured by the underwater substitution method.

[Bubbles on the surface of the cured product]
The compositions obtained in Examples 1 to 4 were poured into a mold of 60 mm × 60 mm × 6 mm and cured into a sheet having a thickness of 2 mm at 120 ° C. for 10 minutes using a press molding machine, and the surface of the cured product was cured. The presence or absence of air bubbles was observed.

H / Vi is the number of moles of hydrogen atom bonded to the silicon atom of component (B) / the number of moles of alkenyl group derived from component (A).

In Examples 1 to 3, the blending amount of the component (C) is in the range of 7,500 to 11,500 parts by mass with respect to 100 parts by mass of the component (A), and the component (C) is.
(C-1) 1,400 to 5,500 parts by mass of a spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less.
(C-2) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 65 μm and 100 μm or less.
(C-3) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 35 μm and 65 μm or less.
(C-4) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 5 μm and 30 μm or less.
(C-5) 1,000 to 4,000 parts by mass of an amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less.
(C-6) A spherical alumina filler having an average particle size of more than 0.2 μm and 0.85 μm or less is composed of 0 to 450 parts by mass, and the components (A), (C) and (F) are heated during stirring. By the treatment, the viscosity of the composition, the thermal conductivity of the cured product, the hardness, the breakdown voltage and the specific gravity were all good, and no bubbles were observed on the surface of the cured product after molding.

Example 4 is the same as in Example 1 except that the components (A), (C) and (F) are not heated during stirring, and the viscosity of the composition, the thermal conductivity of the cured product, the hardness, the breakdown voltage and the insulation breakdown voltage. The specific gravity was also the same as that of Examples 1 to 3. However, bubbles were observed on the surface of the cured product of Example 4.

When the blending amount of the component (C) exceeds 11,500 parts by mass with respect to 100 parts by mass of the component (A) as in Comparative Example 1, the wettability of the composition is insufficient, and a paste-like uniform composition is obtained. I can't get it. As in Comparative Example 2, the blending amount of amorphous alumina having an average particle size of more than 0.85 μm and 5 μm or less, which is the component (C-5), is less than 1,000 parts by mass with respect to 100 parts by mass of the component (A). If there is, the filling property of the composition is remarkably deteriorated, and a paste-like uniform composition cannot be obtained.

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. Is included in the technical scope of.

Claims

Organopolysiloxane having at least two alkenyl groups in one molecule of the following components (A) to (D) (A): 100 parts by mass,
(B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to the silicon atom: The number of moles of the hydrogen atom directly bonded to the silicon atom is 0.1 of the number of moles of the alkenyl group derived from the component (A). ~ 5.0 times the amount,
(C) Thermally conductive filler composed of the following (C-1) to (C-6): 7,500 to 11,500 parts by mass,
(C-1) 1,400 to 5,500 parts by mass of a spherical alumina filler having an average particle size of more than 100 μm and 150 μm or less.
(C-2) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 65 μm and 100 μm or less.
(C-3) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 35 μm and 65 μm or less.
(C-4) 0 to 2,200 parts by mass of a spherical alumina filler having an average particle size of more than 5 μm and 30 μm or less.
(C-5) 1,000 to 4,500 parts by mass of amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less.
(C-6) 0 to 450 parts by mass of a spherical alumina filler having an average particle size of more than 0.2 μm and 0.85 μm or less.
(D) Platinum group metal-based curing catalyst: 0.1 to 2,000 ppm in terms of platinum group element mass with respect to the component (A).
A thermally conductive silicone composition comprising.
Furthermore, as the component (F),
(F-1) The following general formula (1)
R 1 a R 2 b Si (OR 3 ) 4-ab (1)
(In the formula, R 1 is an independently alkyl group having 6 to 15 carbon atoms, R 2 is an independently unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and R 3 is independent. It is an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is an integer of 0 to 2, and a + b is an integer of 1 to 3.)
The alkoxysilane compound represented by (F-2) and the following general formula (2)

(In the formula, R 4 is independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100.)
At least one selected from the group consisting of dimethylpolysiloxane in which one end of the molecular chain represented by is sealed with a trialkoxysilyl group: 0.01 to 300 parts by mass with respect to 100 parts by mass of the component (A). The thermally conductive silicone composition according to claim 1, wherein the composition is one.
Further, as the component (G), the following general formula (3)

(In the formula, R 5 is an independently monovalent hydrocarbon group having 1 to 12 carbon atoms and does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000.)
Organopolysiloxane having a kinematic viscosity of 10 to 100,000 mm 2 / s at 23 ° C. represented by (A) is contained in an amount of 0.1 to 100 parts by mass with respect to 100 parts by mass of the component (A). The thermally conductive silicone composition according to claim 1 or 2.
The thermally conductive silicone composition according to any one of claims 1 to 3, wherein the absolute viscosity at 23 ° C. is 800 Pa · s or less.
A heat-conducting silicone cured product, which is a cured product of the heat-conducting silicone composition according to any one of claims 1 to 4.
The heat conductive silicone cured product according to claim 5, wherein the heat conductivity is 6.5 W / mK or more.
The heat conductive silicone cured product according to claim 5 or 6, wherein the hardness is 60 or less on an Asker C hardness tester.
The thermally conductive silicone cured product according to any one of claims 5 to 7, wherein the dielectric breakdown voltage is 10 kV / mm or more.
The method for producing a thermally conductive silicone composition according to claim 2, further comprising a step of stirring the components (A), (C) and (F) while heating them. A method for producing a silicone composition.