TW202104442A - Thermally conductive silicone composition, method for producing same and thermally conductive silicone cured product - Google Patents

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 [mu]m but not more than 150 [mu]m, (C-5) an amorphous alumina filler that has an average particle diameter of more than 0.85 [mu]m but not more than 5 [mu]m, 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 silicon oxide composition and its manufacturing method, and thermally conductive silicon oxide cured product

The present invention relates to a thermally conductive silicone composition, a method of manufacturing the same, and a thermally conductive silicone cured product. The thermally conductive silicone composition is useful as a heat transfer material. The electronic component is cooled so that it is interposed between the thermal boundary surface of the exothermic electronic component and the interface between the heat dissipation member such as a heat sink or a circuit board.

Large-scale integrated circuit (LSI) chips such as central processing units (CPU), driver ICs, and memory used in electronic devices such as personal computers, digital video disc drives, and mobile phones are becoming more and more high-performance , High-speed, miniaturization, and high-integration, and it will generate a lot of heat, and the temperature rise of the chip caused by the heat will cause poor operation and damage of the chip. Therefore, various heat dissipation methods for suppressing the temperature rise of the operating chip, and heat dissipation members used for the method have been proposed.

In the past, in electronic equipment and the like, in order to suppress the temperature rise of the wafer in operation, a heat sink is used, which uses a metal plate with high thermal conductivity such as aluminum and copper. The heat sink conducts the heat generated by the chip and releases the heat from the surface by the temperature difference with the outside air. In order to efficiently conduct the heat generated from the chip to the heat sink, the heat sink must be closely attached to the chip. However, due to the difference in the height of each chip and the tolerance caused by the assembly process, a flexible sheet or heat sink is used Grease is located between the chip and the heat sink, and heat conduction from the chip to the heat sink is realized through the sheet or heat dissipation paste.

Compared with thermal paste, the sheet has better handling properties, and thermally conductive sheets (thermally conductive silicone rubber sheets) made of thermally conductive silicone rubber have been used in various fields. Patent Document 1 discloses an insulating composition in which at least one metal oxide selected from beryllium oxide, aluminum oxide, hydrated aluminum oxide, magnesium oxide, and zinc oxide is blended with 100 parts by mass of synthetic rubber such as silicone rubber 100 to 800 parts by mass.

On the other hand, due to the high integration of electronic devices such as personal computers, word processors, and CD-ROM drives, the heat generation of integrated circuit components such as LSIs and CPUs in the devices has increased, so The previous cooling method is sometimes insufficient. In particular, when it is a portable notebook personal computer, since the space inside the device is narrow, it is impossible to install a large heat sink and cooling fan. In addition, in these machines, integrated circuit components are mounted on the printed circuit board, and the substrate material is made of glass reinforced epoxy resin or polyimide resin with poor thermal conductivity, so it is impossible to pass the heat dissipation insulating sheet as before. To release heat to the substrate.

Therefore, a method is used, which is to provide a natural cooling type or a forced cooling type heat dissipation component near the integrated circuit component, and conduct the heat generated by the component to the heat dissipation component. If the element and the heat dissipating part are in direct contact in this way, the heat conduction will deteriorate due to the unevenness of the surface, and even if the heat dissipating insulating sheet is installed through the heat dissipating insulating sheet, the flexibility of the heat dissipating insulating sheet will be slightly worse, so it will be caused by thermal expansion. Pressure is applied between the device and the substrate, and there is a risk of damage. In addition, if you want to install heat dissipation parts on each circuit element, additional space is required, and it is difficult to miniaturize the machine. Therefore, a method is sometimes used, which is to combine several elements with one heat dissipation part for cooling. In particular, the ball grid array (BGA) type CPU used in the notebook personal computer generates a large amount of heat due to its lower height compared to other components. Therefore, the cooling method must be fully considered.

Therefore, there is a need for a low-hardness, high-thermal-conductivity material that can fill various gaps caused by the height difference of various components. In order to solve such problems to be solved, a thermally conductive sheet is desired that has excellent thermal conductivity and flexibility to be able to cope with various gaps. At this time, Patent Document 2 discloses a sheet, which is formed by mixing a thermally conductive material such as a metal oxide into a silicone resin, and is formed by laminating soft and easily deformable silicone to have the strength required for processing. On top of the silicone resin layer. In addition, Patent Document 3 discloses a thermally conductive composite sheet, which is a combination of: a silicone rubber layer containing a thermally conductive filler and having an ASKER C hardness of 5-50; and a porous reinforcing material layer, which It has holes with a diameter of 0.3 mm or more. Patent Document 4 discloses a sheet formed by covering the surface of a flexible three-dimensional mesh or foam skeleton lattice with a thermally conductive silicone rubber. Patent Document 5 discloses a thermally conductive composite silicone sheet, which is a sheet or cloth with reinforcing properties inside, and at least one of the sides has adhesiveness, the ASKER C hardness is 5-50, and the thickness is 0.4 mm or less. Patent Document 6 discloses a heat dissipation spacer containing an addition reaction type liquid silicone rubber and a thermally conductive insulating ceramic powder, and the cured product has an ASKER C hardness of 25 or less and a thermal resistance of 3.0° C./W or less.

Since these thermally conductive silicone hardened materials often require insulation, if the thermal conductivity is in the range of 0.5-6 W/mK, alumina is often used as the thermally conductive filler. Generally speaking, although amorphous aluminum oxide has a higher thermal conductivity improvement effect than spherical aluminum oxide, it has disadvantages such as poor filling of silicon oxide, increase in material viscosity due to filling, and deterioration of workability. . In addition, aluminum oxide is very hard with a Mohs (Mohs) hardness of 9, as used in abrasives. Therefore, a thermally conductive silica composition using amorphous alumina having a particle size of 10 μm or more has a problem of grinding the inner wall of the reaction vessel and the stirring blade if a shear force is applied during manufacturing. In this case, the components of the inner wall of the reaction pot and the stirring blade will be mixed into the thermally conductive silica composition, and the insulating properties of the thermally conductive silica composition and the cured product using this composition will be reduced. In addition, the gap between the reaction pot and the stirring blade will be widened, so the stirring efficiency will be reduced, and even if it is manufactured under the same conditions, a certain quality cannot be obtained. In addition, there is a problem that parts must be exchanged frequently in order to prevent this.

In order to solve this problem, there is also a method of using only spherical alumina powder. However, in order to increase the thermal conductivity, it must be filled in a larger amount than amorphous alumina, which causes the viscosity of the composition to increase and the workability to deteriorate. . In addition, since the amount of silica in the composition and its hardened substance will be relatively reduced, the hardness will increase and the compressibility will be poor. In addition, in order to increase the thermal conductivity, there is a method of using thermally conductive fillers with high thermal conductivity, for example, thermally conductive fillers such as aluminum nitride and boron nitride. However, there is a problem of high cost and difficulty in processing. [Prior Technical Literature] (Patent Document)

Patent Document 1: Japanese Patent Laid-Open No. 47-32400 Patent Document 2: Japanese Patent Application Laid-Open No. 2-196453 Patent Document 3: Japanese Patent Laid-Open No. 7-266356 Patent Document 4: Japanese Patent Application Laid-Open No. 8-238707 Patent Document 5: Japanese Patent Application Laid-Open No. 9-1738 Patent Document 6: Japanese Patent Laid-Open No. 9-296114

[The problem to be solved by the invention] The present invention was developed in view of the above reasons, and its purpose is to provide a thermally conductive silicone composition and a cured product thereof. The thermally conductive silicone composition can be suitably used as a thermally conductive resin molded body. The thermally conductive resin molded body is It is installed between heat-generating parts and heat-dissipating parts in electronic equipment for heat dissipation, and has excellent compressibility, insulation, thermal conductivity, and workability, and particularly has a thermal conductivity of 6.5 W/mK or more. [Technical means to solve the problem]

In order to achieve the above-mentioned problem to be solved, the present invention provides a thermally conductive silica composition, which contains the following components (A) to (D): 100 parts by mass of (A) organopolysiloxane, which has at least 2 alkenyl groups in one molecule; (B) Organohydrogen polysiloxane, which has at least 2 hydrogen atoms directly bonded to silicon atoms. The amount of the (B) component is the molar number of hydrogen atoms directly bonded to silicon atoms. An amount of 0.1 to 5.0 times the number of moles of the alkenyl group of the aforementioned component (A); 7,500 to 11,500 parts by mass of (C) thermally conductive filler, which consists of the following (C-1) to (C-6), that is, 1,400 to 5,500 parts by mass (C-1) with an average particle size exceeding Spherical alumina filler of 100 μm and 150 μm or less, 0-2,200 parts by mass of (C-2) Spherical alumina filler having an average particle diameter of more than 65 μm and 100 μm or less, 0-2,200 parts by mass of (C-2) -3) Spherical alumina fillers with an average particle size exceeding 35 μm and 65 μm or less, 0 to 2,200 parts by mass (C-4) Spherical alumina fillers with an average particle size exceeding 5 μm and 30 μm or less, 1,000 to 4,500 parts by mass of (C-5) amorphous alumina filler with an average particle size of more than 0.85 μm and 5 μm or less, and 0 to 450 parts by mass of (C-6) having an average particle size of more than 0.2 μm and 0.85 Spherical alumina filler below μm; (D) A platinum group metal-based hardening catalyst, which is 0.1 to 2,000 ppm in terms of the mass of platinum group elements relative to the aforementioned (A) component.

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

式(1)中，R¹ 獨立地為碳原子數6～15的烷基，R² 獨立地為未被取代或經取代的碳原子數1～12的1價烴基，R³ 獨立地為碳原子數1～6的烷基，a為1～3的整數，b為0～2的整數，並且a＋b為1～3的整數； 該(F-2)是由下述通式(2)表示的分子鏈單末端已被三烷氧基矽烷基封閉之二甲基聚矽氧烷，

式(2)中，R⁴ 獨立地為碳原子數1～6的烷基，c為5～100的整數。The thermally conductive silicone composition preferably further contains 0.01 to 300 parts by mass relative to 100 parts by mass of the aforementioned (A) component, selected from the group consisting of (F-1) and (F-2) As the component (F): This (F-1) is an alkoxysilane compound represented by the following general formula (1),

In formula (1), R ^{1 is} independently an alkyl group having 6 to 15 carbon atoms, R ^{2 is} independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and R ^{3 is} independently carbon An alkyl group having 1 to 6 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; this (F-2) is represented by the following general formula (2) The single end of the molecular chain of dimethylpolysiloxane has been blocked by trialkoxysilyl groups,

In the formula (2), R ^{4 is} independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100.

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

式(3)中，R⁵ 獨立地為碳原子數1～12的不含脂肪族不飽和鍵之1價烴基，d為5～2,000的整數。The thermally conductive silicone composition preferably further contains 0.1-100 parts by mass of the component (G) as an organopolysiloxane represented by the following general formula (3) with respect to 100 parts by mass of the aforementioned (A) component The dynamic viscosity of the organopolysiloxane at 23℃ is 10～100,000 mm ² /s,

In the formula (3), R ^{5 is} independently a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000.

If the thermally conductive silicone composition contains the organopolysiloxane represented by the above-mentioned general formula (3), the flexibility of the cured product of the composition, that is, the thermally conductive silicone cured product, will be further improved.

The thermally conductive silicone composition preferably has an absolute viscosity of 800 Pa·s or less at 23°C. If the absolute viscosity of the thermally conductive silica composition is as described above, the formability of the composition will be further improved.

In addition, the present invention provides a thermally conductive silicone cured product, which is a cured product of the above-mentioned thermally conductive silicone composition. This thermally conductive silicone cured product has excellent compressibility, insulation, thermal conductivity, and processability, and has a thermal conductivity of 6.5 W/mK or more.

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

The thermally conductive silicone cured product preferably has a hardness of 60 or less as measured by an ASKER C hardness meter. If the hardness of the thermally conductive silicone cured product is as described above, the cured product will be deformed along the shape of the heat-receiving body, and will show good heat dissipation characteristics without applying stress to the heat-receiving body.

The thermally conductive silicon-oxygen cured product preferably has an insulation breakdown voltage of 10 kV/mm or more. If the dielectric breakdown voltage of the thermally conductive silicone cured product is as described above, the cured product can ensure more stable insulation during use.

In addition, the present invention provides a method for producing a thermally conductive silicone composition, which has a step of heating and stirring the aforementioned components (A), (C), and (F). With this thermally conductive silicon-oxygen composition manufacturing method, a thermally conductive silicon-oxygen composition can be manufactured, which can obtain a specific hardened product, which has reduced the generation of bubbles on the surface. [effect]

The thermally conductive silica composition of the present invention has a specific blending amount of amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less, and balls with an average particle size of more than 0.2 μm and 100 μm or less as required Alumina fillers are used together with spherical alumina fillers with an average particle size of more than 100 μm and 150 μm or less. Because the large-diameter spherical alumina fillers will make up for the shortcomings of the small-sized amorphous alumina fillers, and Amorphous alumina filler with a small particle size will make up for the shortcomings of a spherical alumina filler with a large particle size, and thus a thermally conductive silica composition can be provided. The thermally conductive silica composition can obtain a thermally conductive silica cured product. This thermally conductive silicone cured product is excellent in compressibility, insulation, thermal conductivity, and processability, and particularly has a thermal conductivity of 6.5 W/mK or more. In addition, in the step of manufacturing the above-mentioned composition, it is possible to reduce bubbles generated on the surface of the cured product after molding by heating while stirring.

As mentioned above, it has been sought to develop a thermally conductive silicone composition and its hardened product. The thermally conductive silicone composition can be suitably used as a thermally conductive resin molded body, and the thermally conductive resin molded body is installed on a heat generating part. It is used for heat dissipation between heat dissipation parts and has excellent compressibility, insulation, thermal conductivity, and processability.

In order to achieve the above-mentioned object, the inventors have made great efforts to conduct research. As a result, they have found the following fact: the average particle size of the amorphous alumina filler with a specific blending amount of more than 0.85 μm and less than 5 μm is A spherical alumina filler exceeding 0.2 μm and 100 μm or less can be used in combination with a spherical alumina filler having an average particle diameter of more than 100 μm and 150 μm or less to solve the above-mentioned problem. In other words, by blending a spherical alumina filler with a small specific surface area and an average particle size of more than 100 μm and 150 μm or less, it is possible to effectively improve the thermal conductivity, and to provide a silica composition with low viscosity and excellent workability. Hardened object. In addition, by combining amorphous alumina fillers with an average particle size of more than 0.85 μm and 5 μm or less, and spherical alumina fillers with an average particle size of more than 0.2 μm and 100 μm or less as required, the composition can be improved. The fluidity of the material improves the processability. In addition, since particles with a particle size of 10 μm or more use spherical alumina fillers and do not use amorphous alumina fillers with a large polishing effect, the abrasion of the reaction pot and the stirring blade is suppressed and the insulation is improved.

In other words, the inventors found the following facts and completed the present invention: a spherical alumina filler with a large particle size can make up for the shortcomings of an amorphous alumina filler with a small particle size, and an amorphous alumina filler with a small particle size can make up for The shortcomings of the large particle diameter spherical alumina filler can obtain a thermally conductive silica composition and its hardened product, which have excellent compressibility, insulation, thermal conductivity, and processability, and especially have 6.5 W/mK or more High thermal conductivity and low cost.

In other words, the present invention is a thermally conductive silica composition comprising the following components (A) to (D): 100 parts by mass of (A) organopolysiloxane, which has at least 2 alkenyl groups in one molecule; (B) Organohydrogen polysiloxane, which has at least 2 hydrogen atoms directly bonded to silicon atoms. The amount of the (B) component is the molar number of hydrogen atoms directly bonded to silicon atoms. An amount of 0.1 to 5.0 times the number of moles of the alkenyl group of the aforementioned component (A); 7,500 to 11,500 parts by mass of (C) thermally conductive filler, which consists of the following (C-1) to (C-6), that is, 1,400 to 5,500 parts by mass (C-1) with an average particle size exceeding Spherical alumina filler of 100 μm and 150 μm or less, 0-2,200 parts by mass of (C-2) Spherical alumina filler having an average particle diameter of more than 65 μm and 100 μm or less, 0-2,200 parts by mass of (C-2) -3) Spherical alumina fillers with an average particle size exceeding 35 μm and 65 μm or less, 0 to 2,200 parts by mass (C-4) Spherical alumina fillers with an average particle size exceeding 5 μm and 30 μm or less, 1,000 to 4,500 parts by mass of (C-5) amorphous alumina filler with an average particle size of more than 0.85 μm and 5 μm or less, and 0 to 450 parts by mass of (C-6) having an average particle size of more than 0.2 μm and 0.85 Spherical alumina filler below μm; (D) A platinum group metal-based hardening catalyst, which is 0.1 to 2,000 ppm in terms of the mass of platinum group elements relative to the aforementioned (A) component.

Hereinafter, the present invention will be described in detail, but the present invention is not limited by these. The thermally conductive silicone composition of the present invention contains: (A) organopolysiloxane containing alkenyl groups, (B) organohydrogenpolysiloxane, (C) thermally conductive filler, and (D) platinum group metal Department of hardening catalyst.

[Organic polysiloxanes containing alkenyl groups] The component (A) is an organopolysiloxane containing alkenyl groups, which has two or more alkenyl groups bonded to silicon atoms in one molecule, and it becomes the thermally conductive silicon of the present invention. The main agent of oxygen hardened substance. Generally speaking, the main chain part is basically composed of repeating units of diorganosiloxane units. This part of the molecular structure may include a branched structure, and it may also be a cyclic body. From the viewpoint of physical properties such as mechanical strength of the object, a linear diorganopolysiloxane is preferred.

The functional group other than the alkenyl group bonded to the silicon atom is an unsubstituted or substituted monovalent hydrocarbon group, and examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, Alkyl groups such as tertiary butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; benzene Benzyl, tolyl, xylyl, naphthyl, biphenyl and other aryl groups; benzyl, phenethyl, phenylpropyl, methyl benzyl and other aralkyl groups; and the carbon atoms in these groups Groups in which part or all of the bonded hydrogen atoms are substituted by halogen atoms such as fluorine, chlorine, bromine, etc., cyano groups, etc., for example: chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3 -Trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Representative groups are groups with 1 to 10 carbon atoms, and more representative groups are groups with 1 to 6 carbon atoms, such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3 , 3,3-trifluoropropyl, cyanoethyl and other unsubstituted or substituted alkyl groups with 1 to 3 carbon atoms, and unsubstituted or substituted alkyl groups such as phenyl, chlorophenyl, and fluorophenyl Phenyl is preferred. In addition, the functional groups other than the alkenyl group bonded to the silicon atom are not limited to all being the same.

In addition, examples of alkenyl groups include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, and other alkenyl groups usually having about 2 to 8 carbon atoms. , Lower alkenyl groups such as vinyl and allyl are preferred, and vinyl is preferred. Furthermore, it is preferable that two alkenyl groups are present in the molecule. However, in order to make the obtained hardened product good in flexibility, it is preferable to be present in such a way that it is only bonded to the silicon atom at the end of the molecular chain.

The dynamic viscosity of the organopolysiloxane at 23°C is usually preferably in ^{the range of 10 to 100,000 mm 2} /s, and more preferably in the range of 500 to 50,000 mm ² /s. If the aforementioned viscosity is 10 mm ² /s or more, the storage stability of the obtained composition is good, and if the aforementioned viscosity is 100,000 mm ² /s or less, the stretchability of the obtained composition is improved. Furthermore, the dynamic viscosity is the value when the Ostwald viscosity is used (the same below). The organopolysiloxane of this (A) component may be used alone or in combination of two or more kinds with different viscosities.

[Organic Hydrogen Polysiloxane] The organohydrogen polysiloxane of component (B) is an organohydrogen polysiloxane that has an average of 2 or more, preferably 2 to 100 hydrogen atoms directly bonded to silicon atoms (Si- H group), and is a component that functions as a crosslinking agent of the component (A). In other words, the Si-H group in the component (B) and the alkenyl group in the component (A) will be added by the hydrosilylation reaction to obtain a three-dimensional network structure with a cross-linked structure, and the hydrosilylation reaction will be affected by It is promoted by the platinum group metal-based hardening catalyst of the component (D) described later. Furthermore, when the number of Si-H groups is less than 2, it will not harden.

式(4)中，R⁶ 獨立地為氫原子或不含脂肪族不飽和鍵之未被取代或經取代的1價烴基，但至少2個、較佳是2～10個為氫原子，e為1以上的整數，以10～200的整數為佳。As the organohydrogenpolysiloxane, the organohydrogenpolysiloxane represented by the following average structural formula (4) is used, but it is not limited to this.

In formula (4), R ^{6 is} independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, but at least two, preferably 2-10, are hydrogen atoms, e It is an integer of 1 or more, preferably an integer of 10 to 200.

In the formula (4), the ^{unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond other than the hydrogen atom of R 6} includes, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, Butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl and other alkyl groups; cyclopentyl, cyclohexyl, cycloheptyl Cycloalkyl groups such as phenyl groups; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenyl groups; aralkyl groups such as benzyl, phenethyl, phenylpropyl, and methylbenzyl; and this A group in which part or all of the hydrogen atoms bonded to the carbon atoms of an equivalent group are substituted by halogen atoms such as fluorine, chlorine, bromine, etc., and cyano groups, such as: chloromethyl, 2-bromoethyl, and 3-chloropropyl , 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Representative groups are groups with 1 to 10 carbon atoms, and more representative groups are groups with 1 to 6 carbon atoms, such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3 , 3,3-trifluoropropyl, cyanoethyl and other unsubstituted or substituted alkyl groups with 1 to 3 carbon atoms, and unsubstituted or substituted alkyl groups such as phenyl, chlorophenyl, and fluorophenyl Phenyl is preferred. In addition, R ⁶ is not limited to all being the same.

The amount of component (B) added is such that the Si-H group derived from the component (B) becomes 0.1 to 5.0 mol relative to 1 mol of the alkenyl group derived from the component (A), so that it becomes 0.3 to 2.0 mol. The amount of ears is preferable, and the amount is more preferably 0.5 to 1.0 mol. If the Si-H group derived from the component (B) is less than 0.1 mol relative to 1 mol of the alkenyl group derived from the component (A), the thermally conductive silicone composition may not be cured, or the strength of the cured product may be It is insufficient and cannot maintain the shape of the molded body and cannot be handled. In addition, if it exceeds 5.0 mol, the flexibility of the hardened product will be lost, and the hardened product will become brittle.

[Thermal Conductive Filling Material] The component (C), the thermally conductive filler, is composed of the following (C-1) to (C-6): (C-1) Spherical alumina fillers with an average particle diameter of more than 100 μm and 150 μm or less, (C-2) Spherical alumina filler with an average particle diameter of more than 65 μm and less than 100 μm, (C-3) Spherical alumina filler with an average particle diameter of more than 35 μm and less than 65 μm, (C-4) Spherical alumina fillers with an average particle diameter of more than 5 μm and 30 μm or less, (C-5) Amorphous alumina fillers with an average particle diameter of more than 0.85 μm and 5 μm or less, (C-6) A spherical alumina filler having an average particle diameter of more than 0.2 μm and 0.85 μm or less. In addition, in the present invention, the above-mentioned average particle diameter is, for example, a value of a volume-based cumulative average particle diameter (median diameter) measured using a particle size analyzer manufactured by Nikkiso Co., Ltd., that is, MICROTRAC MT3300EX.

The spherical alumina filler of the component (C-1) can improve the thermal conductivity to be excellent. (C-1) The average particle size of the spherical alumina filler of the component is more than 100 μm and 150 μm or less, preferably 105 to 140 μm. If the average particle size of the spherical alumina filler of the component (C-1) is greater than 150 μm, the abrasion of the reaction pot and the stirring blade will be more significant, and the insulation of the composition will be reduced. (C-1) The spherical alumina filler of the component can be used singly or in combination of two or more.

The spherical alumina filler of component (C-2) to (C-4) improves the thermal conductivity of the composition and provides a barrier effect which suppresses the amorphous alumina filler of component (C-5) The contact with the reaction pot and the stirring wing suppresses abrasion. Regarding the average particle size, (C-2) component is more than 65 μm and 100 μm or less, preferably 70 to 95 μm, (C-3) component is more than 35 μm and 65 μm or less, preferably 40 to 60 μm , (C-4) component is more than 5 μm and 30 μm or less, preferably 7-25 μm. As the spherical alumina filler of the components (C-2) to (C-4), one type or two or more types can be used in combination.

The amorphous alumina filler of the component (C-5) also has the effect of improving the thermal conductivity of the composition, but its main function is to adjust the viscosity of the composition, improve the lubricity, and improve the filling property. (C-5) The average particle size of the component is more than 0.85 μm and 5 μm or less. Since the above characteristics are exhibited, it is preferably 0.9 to 4 μm.

The main function of the spherical alumina filler of component (C-6) is to adjust the viscosity of the composition, improve lubricity, and improve filling properties. (C-6) The average particle size of the component is more than 0.2 μm and 0.85 μm or less. If the average particle size is less than 0.2 μm, the viscosity of the composition will increase significantly, and the formability will be greatly impaired.

The compounding amount of (C-1) component is 1,400-5,500 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1,800-4,000 mass parts. If the blending amount of the component (C-1) is too small, it is difficult to increase the thermal conductivity, and if it is too large, the abrasion of the reaction pot and the stirring blade will be more significant, and the insulation of the composition will be reduced.

The blending amounts of (C-2) to (C-4) components are 0-2,200 parts by mass, preferably 900-1,600 parts by mass relative to 100 parts by mass of (A) component. If the components (C-2) to (C-4) are blended separately, the thermal conductivity of the cured product will be increased, and if too much, the fluidity of the composition will be lost and the moldability will be impaired.

The compounding amount of (C-5) component is 1,000-4,000 mass parts with respect to 100 mass parts of (A) component, Preferably it is 2,000-2,800 mass parts. If the blending amount of the component (C-5) is too small, the fluidity of the composition will be lost, and the moldability will be impaired. Even if more than 4,000 parts by mass of the (C-5) component is blended, it is difficult to increase the thermal conductivity of the cured product.

The compounding amount of (C-6) component is 0-450 mass parts with respect to 100 mass parts of (A) components, Preferably it is 250-400 mass parts. If the component (C-6) is blended, the fluidity improvement effect of the composition will be exhibited.

And, relative to 100 parts by mass of (A) component, the blending amount of (C) component (the total blending amount of (C-1) to (C-6) components) is 7,500 to 11,500 parts by mass, and 7,600 to 9,000 parts by mass Better. When the blending amount is less than 7,500 parts by mass, the thermal conductivity of the obtained cured product will deteriorate, and when it exceeds 11,500 parts by mass, the fluidity of the composition will be lost and the moldability will be impaired.

The use of the component (C) in the above-mentioned blended amount enables the effect of the present invention described above to be achieved more favorably and reliably.

[Platinum group metal hardening catalyst] The platinum group metal hardening catalyst of the component (D) promotes the addition reaction of the alkenyl group derived from the component (A) and the Si-H group derived from the component (B) Examples of catalysts include catalysts that are well-known as catalysts used in the hydrosilylation reaction. Specific examples include platinum (including platinum black), rhodium, palladium and other platinum group metal monomers; H ₂ PtCl ₄ ·nH ₂ O, H ₂ PtCl ₆ ·nH ₂ O, NaHPtCl 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 0-6, preferably 0 or 6), such as platinum chloride, chloroplatinic acid and chloroplatinic acid; alcohols modified chloroplatinic acid (refer to the specification of US Patent No. 3,220,972); chloroplatinic acid and alkene Composite (U.S. Patent No. 3,159,601 Specification, U.S. Patent No. 3,159,662 Specification, U.S. Patent No. 3,775,452 Specification); a product made by supporting platinum group metals such as platinum black and palladium on a carrier such as alumina, silicon oxide, and carbon ; Rhodium-olefin complex; Chlorine ginseng (Triphenylphosphine) rhodium (Wilkinson's catalyst); Platinum chloride, chloroplatinic acid or chloroplatinate and vinyl silicone, especially ethylene Compounds of cyclic siloxanes, etc.

The amount of component (D) used is 0.1 to 2,000 ppm in terms of mass of platinum group elements relative to component (A), preferably 50 to 1,000 ppm.

[Addition reaction control agent] The thermally conductive silicone composition of the present invention can further use an addition reaction control agent as the (E) component. The addition reaction control agent can use all conventional addition reaction control agents used in ordinary addition reaction hardening type silicone compositions. For example: 1-ethynyl-1-hexanol, 3-butyn-1-ol, ethynylmethylidene carbinol and other acetylene compounds and various nitrogen compounds, organophosphorus compounds, oxime compounds , Organochlorine compounds, etc.

When the (E) component is blended, the usage amount is preferably 0.01 to 1 part by mass, preferably about 0.1 to 0.8 part by mass, relative to 100 parts by mass of the (A) component. If the blending amount of the aforementioned (E) component is equal to or less than the aforementioned upper limit, the curing reaction proceeds without impairing the molding efficiency.

[Surface treatment agent] In the thermally conductive silica composition of the present invention, a surface treatment agent of component (F) can be formulated for the following purpose: when the composition is prepared, component (C), which is a thermally conductive filler, is hydrophobized, and Improve the wettability with the (A) component, which is the organopolysiloxane, and make the (C) component, which is the thermally conductive filler, uniformly dispersed in the base material composed of the (A) component. As this (F) component, (F-1) component and (F-2) component shown below are especially preferable.

式(1)中，R¹ 獨立地為碳原子數6～15的烷基，R² 獨立地為未被取代或經取代的碳原子數1～12的1價烴基，R³ 獨立地為碳原子數1～6的烷基，a為1～3的整數，b為0～2的整數，並且a＋b為1～3的整數。The component (F-1) is an alkoxysilane compound represented by the following general formula (1):

In formula (1), R ^{1 is} independently an alkyl group having 6 to 15 carbon atoms, R ^{2 is} independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and R ^{3 is} independently carbon An alkyl group having 1 to 6 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 general formula (1), ^{examples of the alkyl group represented by R 1} include hexyl, octyl, nonyl, decyl, dodecyl, and tetradecyl. If 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) and the handling properties are good, and the low-temperature characteristics of the composition are good.

As the ^{unsubstituted or substituted monovalent hydrocarbon group represented by R 2} , for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, new Alkyl groups such as pentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; phenyl, tolyl, xylyl, Aryl groups such as naphthyl and biphenyl; aralkyl groups such as benzyl, phenethyl, phenylpropyl, and methylbenzyl; and part or all of the hydrogen atoms bonded to the carbon atoms of these groups Fluorine, chlorine, bromine and other halogen atoms, cyano groups and other substituted groups, such as: chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, Fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Representative groups are groups with 1 to 10 carbon atoms, and particularly representative groups are groups with 1 to 6 carbon atoms, such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3 , 3,3-trifluoropropyl, cyanoethyl and other unsubstituted or substituted alkyl groups with 1 to 3 carbon atoms, and unsubstituted or substituted alkyl groups such as phenyl, chlorophenyl, and fluorophenyl Phenyl is preferred. Examples of R ³ include methyl, ethyl, propyl, butyl, and hexyl.

式(2)中，R⁴ 獨立地為碳原子數1～6的烷基，c為5～100的整數，以5～70的整數為佳，以10～50的整數較佳。(F-2) is a dimethylpolysiloxane whose single end of the molecular chain represented by the following general formula (2) has been blocked by a trialkoxysilyl group:

In the formula (2), R ^{4 is} independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100, preferably an integer of 5 to 70, and more preferably an integer of 10 to 50.

The surface treatment agent as the (F) component may be any one of the (F-1) component and the (F-2) component, or a combination of both. When compounding the (F) component, the compounding amount is preferably 0.01 to 300 parts by mass, and more preferably 0.1 to 200 parts by mass relative to 100 parts by mass of the (A) component. If the blending amount of the component (F) is equal to or less than the aforementioned upper limit, oil separation will not occur.

式(3)中，R⁵ 獨立地為碳原子數1～12的不含脂肪族不飽和鍵之1價烴基，d為5～2,000的整數。[Organopolysiloxane] In the thermally conductive silicone composition of the present invention, for the purpose of imparting characteristics such as a viscosity modifier of the thermally conductive silicone composition, a compound represented by the following general formula (3) can be added. Organopolysiloxane with a dynamic viscosity of 10 to 100,000 mm ² /s at ℃ is used as the (G) component. (G) A component can be used individually by 1 type or in combination of 2 or more types.

In the formula (3), R ^{5 is} independently a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000.

In the above general formula (3), R ^{5 is} independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms and not containing an aliphatic unsaturated bond. Examples of R ⁵ include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl Alkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, biphenyl, etc.; benzyl, benzene Aralkyl groups such as ethyl, phenylpropyl, and methylbenzyl; and part or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted by halogen atoms such as fluorine, chlorine, bromine, etc., cyano groups, etc. Group, for example: chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4 ,5,5,6,6,6-nonafluorohexyl etc. Representative groups are groups with 1 to 10 carbon atoms, and particularly representative groups are groups with 1 to 6 carbon atoms, such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3 , 3,3-trifluoropropyl, cyanoethyl and other unsubstituted or substituted alkyl groups with 1 to 3 carbon atoms, and unsubstituted or substituted alkyl groups such as phenyl, chlorophenyl, and fluorophenyl Phenyl is preferred, and methyl and phenyl are preferred. From the viewpoint of the required viscosity, the above-mentioned d is preferably an integer of 5 to 2,000, and more preferably an integer of 10 to 1,000.

In addition, the dynamic viscosity of the component (G) at 23°C is preferably 10 to 100,000 mm ² /s, and more preferably 100 to 10,000 mm ² /s. If the dynamic viscosity is 10 mm ² /s or more, the obtained thermally conductive silicone cured product will not leak oil. If the dynamic viscosity is 100,000 mm ² /s or less, the obtained thermally conductive silicone cured product has sufficient flexibility.

When the (G) component is blended in the thermally conductive silicone composition of the present invention, the blending amount is not particularly limited, as long as it is an amount that can obtain the desired effect, and is based on 100 parts by mass of the aforementioned (A) component 0.1-100 parts by mass is preferred, and 1-50 parts by mass is preferred. If the blending amount is within this range, it is easy to maintain good fluidity and workability in the thermally conductive silicone composition before curing, and it is easy to fill the composition with the thermally conductive filler of component (C).

[Other ingredients] The thermal conductive silica composition of the present invention may further be blended with other components. For example: heat resistance improvers such as iron oxide and cerium oxide; viscosity modifiers such as silica; coloring agents; mold release agents and other optional ingredients.

[Viscosity of thermally conductive silica composition] The absolute viscosity of the thermally conductive silicone composition of the present invention is preferably 800 Pa·s or less at 23° C., and more preferably 700 Pa·s or less. If the viscosity is 800 Pa·s or less, the formability of the composition will not be impaired. The lower limit is not particularly limited, and the insulation viscosity can be set to 100 Pa·s or more, for example. Furthermore, in the present invention, the viscosity is measured in accordance with the use of a B-type viscometer.

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

[Manufacturing Method of Thermally Conductive Silicon Oxide Cured Material] The curing conditions for forming the thermally conductive silicone composition can be the same as the conventional addition reaction curing type silicone rubber composition. For example, although it will be fully cured at room temperature, it can be heated as needed. It is preferable to make the addition hardening at 100-120°C for 8-12 minutes. Such a cured silicon oxide of the present invention has excellent thermal conductivity.

[The thermal conductivity of thermally conductive silicone hardened material] The thermal conductivity of the thermally conductive silicone cured product of the present invention is preferably: the measured value at 23°C measured by the hot disc method is 6.5 W/mK or more, more preferably 7.0 W/ Above mK. The upper limit is not particularly limited, and the thermal conductivity can be set to 8.0 W/mK or less, for example.

[Hardness of thermally conductive silicone cured material] The hardness of the thermally conductive silicone cured product in the present invention is a measured value at 23°C measured by an ASKER C hardness meter, preferably 60 or less, preferably 40 or less, more preferably 30 or less, and 5 or more is better. When the hardness is 60 or less, it deforms along the shape of the radiated body and exhibits good heat dissipation characteristics without applying stress to the radiated body. In addition, such hardness can be adjusted by changing the ratio of (A) component and (B) component to adjust the crosslinking density.

[Dielectric breakdown voltage of thermally conductive silicone hardened material] The dielectric breakdown voltage of the thermally conductive silicone cured product of the present invention is a measured value when the dielectric breakdown voltage of a 1 mm thick molded body is measured in accordance with JIS K 6249, and preferably 10 kV or more , Preferably above 13 kV. In the case of a sheet with a dielectric breakdown voltage of 10 kV/mm or more, the insulation can be stably ensured during use. The upper limit is not particularly limited, and the dielectric breakdown voltage can be set to 25 kV/mm or less, for example. Furthermore, such a dielectric breakdown voltage can be adjusted by adjusting the type and purity of the filler. [Example]

Hereinafter, examples and comparative examples are given to specifically illustrate the present invention, but the present invention is not limited by the following examples. In addition, the dynamic viscosity is measured using an Austenitic viscometer at 23°C. In addition, the average particle diameter is the value of the cumulative average particle diameter (median diameter) measured on a volume basis using a particle size analyzer manufactured by Nikkiso Co., Ltd., that is, MICROTRAC MT3300EX.

式(5)中，X為乙烯基，f為能夠獲得上述黏度的數值。 (B)成分：由下述式(6)表示的有機氫聚矽氧烷

式(6)中，g為27，h為3。The components (A) to (F) used in the following examples and comparative examples are as follows. (A) Component: The following two kinds of organopolysiloxane (A-1) components: The organopolysiloxane (A-2) component with ^{a dynamic viscosity of 400 mm 2 /s represented by the following formula (5):} Organopolysiloxane with a dynamic viscosity of 30,000 mm ² /s expressed by the following formula (5)

In the formula (5), X is a vinyl group, and f is a value capable of obtaining the aforementioned viscosity. (B) Component: Organohydrogen polysiloxane represented by the following formula (6)

In formula (6), g is 27 and h is 3.

(C) Component: The average particle size is spherical alumina and amorphous alumina as described below (C-1) Spherical alumina with an average particle size of 124.2 μm (C-2) Spherical alumina with 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) Amorphous alumina with an average particle size of 2.4 μm (C-6) Spherical alumina with an average particle size of 0.8 μm

(D) Component: 5% by mass chloroplatinic acid 2-ethylhexanol solution (E) Component: ethynylmethine methanol as an addition reaction control agent

(F) Component: Dimethylpolysiloxane represented by the following formula (7) with an average degree of polymerization of 30 and one end of which has been blocked by a trialkoxysilyl group

式(8)中，j為80。(G) Component: Dimethyl polysiloxane represented by the following formula (8) as a plasticizer

In formula (8), j is 80.

>Examples 1 to 4, Comparative Examples 1 to 2> In Examples 1 to 4 and Comparative Examples 1 to 2, the components (A) to (G) were used in the amounts shown in Table 1 below to prepare the composition in the following manner, and the composition was measured in accordance with the following method的viscosity. After the composition is formed and cured, the thermal conductivity, hardness, dielectric breakdown voltage, specific gravity, and bubbles on the surface of the cured product obtained are measured or observed in accordance with the following methods. The results are shown in Table 1.

[Preparation of composition] After adding the components (A), (C), and (F) in the predetermined blending amounts shown in Examples 1 to 4 and Comparative Examples 1 to 2 in Table 1 below, and kneading them for 30 minutes using a planetary mixer, Knead by heating at 145°C for 60 minutes, or knead without heating. After sufficient cooling, the predetermined blending amounts of (D) and (G) components shown in Examples 1 to 4 and Comparative Examples 1 to 2 in Table 1 below were added, and an effective amount of Shin-Etsu Chemical Co., Ltd. was further added. Phenyl-modified silicone oil, KF-54, is used as an internal mold release agent and kneaded for 30 minutes. The internal mold release agent is used to promote mold release from the spacer. The components (B) and (E) of predetermined blending amounts shown in Examples 1 to 4 and Comparative Examples 1 to 2 of Table 1 below were further added thereto, and they were kneaded for 30 minutes to obtain a composition.

[Viscosity] A type B viscometer was used to measure the viscosity of the compositions obtained in Examples 1 to 4 in an environment of 23°C.

[Thermal conductivity] The composition obtained in Examples 1 to 4 was injected into a mold of 60 mm × 60 mm × 6 mm, and a press molding machine was used to harden it into a 6 mm thick sheet at 120°C for 10 minutes Two sheets of the sheet were used to measure the thermal conductivity of the sheet using a thermal conductivity meter (trade name: TPS-2500S, manufactured by Kyoto Electronics Industry Co., Ltd.).

[hardness] In the same manner as described above, the compositions obtained in Examples 1 to 4 were hardened into 6 mm thick flakes, and the two flakes were stacked, and then the hardness of the flakes was measured with an ASKER C hardness meter.

[Dielectric destruction voltage] The composition obtained in Examples 1 to 4 was injected into a mold of 60 mm × 60 mm × 6 mm, and a press molding machine was used to harden it into a 1 mm thick sheet at 120°C for 10 minutes After forming, the dielectric breakdown voltage was measured in accordance with JIS K 6249.

[proportion] The composition obtained in Examples 1 to 4 was injected into a mold of 60 mm × 60 mm × 6 mm, and a press molding machine was used to harden it into a 1 mm thick sheet at 120°C for 10 minutes After the shape, the specific gravity of the hardened product was measured by the water displacement method.

[Bubble on the surface of the hardened material] The composition obtained in Examples 1 to 4 was injected into a mold of 60 mm × 60 mm × 6 mm, and a pressure molding machine was used to harden it into a 2 mm thick sheet at 120°C for 10 minutes After the shape, observe whether there are bubbles on the surface of the hardened product.

H/Vi為(B)成分的與矽原子鍵結的氫原子的莫耳數/源自(A)成分的烯基的莫耳數。[Table 1]

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

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

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

If the blending amount of the (C) component exceeds 11,500 parts by mass relative to 100 parts by mass of the (A) component as in Comparative Example 1, the wettability of the composition is insufficient, and a paste-like uniform composition cannot be obtained. If, as in Comparative Example 2, relative to 100 parts by mass of (A) component, (C-5) component, which is an amorphous alumina filler having an average particle size of more than 0.85 μm and 5 μm or less, does not reach 1,000 parts by mass, The filling property of the composition was significantly deteriorated, and a paste-like uniform composition could not be obtained.

In addition, the present invention is not limited to the above-mentioned embodiment. The above-mentioned embodiments are only examples, and as long as they have substantially the same configuration and produce the same effects as the technical ideas described in the scope of the patent application of the present invention, whatever they are, they are included in the technical scope of the present invention.

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Claims (17)

A thermally conductive silica composition characterized by containing the following components (A) to (D): 100 parts by mass of (A) organopolysiloxane, which has at least 2 alkenyl groups in one molecule; (B) Organohydrogen polysiloxane, which has at least 2 hydrogen atoms directly bonded to silicon atoms, and the amount of component (B) is the molar number of hydrogen atoms directly bonded to silicon atoms. (A) An amount of 0.1 to 5.0 times the number of moles of the alkenyl group of the component; 7,500 to 11,500 parts by mass of (C) thermally conductive filler, which consists of the following (C-1) to (C-6), that is, 1,400 to 5,500 parts by mass (C-1) with an average particle size exceeding Spherical alumina filler of 100 μm and 150 μm or less, 0-2,200 parts by mass of (C-2) Spherical alumina filler having an average particle size of more than 65 μm and 100 μm or less, 0-2,200 parts by mass of (C-2) -3) Spherical alumina fillers with an average particle size exceeding 35 μm and 65 μm or less, 0 to 2,200 parts by mass (C-4) Spherical alumina fillers with an average particle size exceeding 5 μm and 30 μm or less, 1,000 to 4,500 parts by mass of (C-5) amorphous alumina filler with an average particle diameter of more than 0.85 μm and 5 μm or less, and 0 to 450 parts by mass of (C-6) with an average particle diameter of more than 0.2 μm and 0.85 Spherical alumina filler below μm; (D) A platinum group metal-based hardening catalyst, which is 0.1 to 2,000 ppm in terms of the mass of platinum group elements relative to the aforementioned (A) component. The thermally conductive silicone composition according to claim 1, which further contains 0.01 to 300 parts by mass with respect to 100 parts by mass of the aforementioned (A) component from the following (F-1) and (F-2) At least one selected from the group consisting of is used as component (F): This (F-1) is an alkoxysilane compound represented by the following general formula (1),

In formula (1), R ^{1 is} independently an alkyl group having 6 to 15 carbon atoms, R ^{2 is} independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and R ^{3 is} independently carbon An alkyl group having 1 to 6 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; this (F-2) is represented by the following general formula (2) The single end of the molecular chain of dimethylpolysiloxane has been blocked by trialkoxysilyl groups,

In the formula (2), R ^{4 is} independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100. The thermally conductive silicone composition according to claim 1, which further contains 0.1-100 parts by mass relative to 100 parts by mass of the aforementioned (A) component as the (G) component represented by the following general formula (3) The organopolysiloxane has a dynamic viscosity of 10～100,000 mm ² /s at 23°C,

In the formula (3), R ^{5 is} independently a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000. The thermally conductive silica composition according to claim 2, which further contains 0.1-100 parts by mass relative to 100 parts by mass of the aforementioned (A) component as the (G) component represented by the following general formula (3) The organopolysiloxane has a dynamic viscosity of 10～100,000 mm ² /s at 23°C,

In the formula (3), R ^{5 is} independently a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond, and d is an integer of 5 to 2,000. The thermally conductive silica composition according to claim 1, wherein the absolute viscosity at 23°C is 800 Pa·s or less. The thermally conductive silica composition according to claim 2, wherein the absolute viscosity at 23°C is 800 Pa·s or less. The thermally conductive silica composition according to claim 3, wherein the absolute viscosity at 23°C is 800 Pa·s or less. The thermally conductive silica composition according to claim 4, wherein the absolute viscosity at 23°C is 800 Pa·s or less. A thermally conductive silicone cured product characterized by being a cured product of the thermally conductive silicone composition according to any one of claims 1 to 8. The thermally conductive cured silicon oxide according to claim 9, wherein the thermal conductivity is 6.5 W/mK or more. The thermally conductive silicone cured product according to claim 9, wherein the hardness measured by an ASKER C hardness meter is 60 or less. The thermally conductive silicone cured product according to claim 10, wherein the hardness measured by an ASKER C hardness meter is 60 or less. The thermally conductive cured silicon oxide according to claim 9, wherein the dielectric breakdown voltage is 10 kV/mm or more. The thermally conductive cured silicon oxide according to claim 10, wherein the dielectric breakdown voltage is 10 kV/mm or more. The thermally conductive cured silicon oxide according to claim 11, wherein the dielectric breakdown voltage is 10 kV/mm or more. The thermally conductive cured silicon oxide according to claim 12, wherein the dielectric breakdown voltage is 10 kV/mm or more. A method of manufacturing a thermally conductive silica composition is a method of manufacturing the thermally conductive silica composition according to claim 2, and the manufacturing method is characterized by having the aforementioned components (A), (C) and (F) The step of stirring while heating.