TW202311486A - Thermally conductive silicone composition and cured product of same - 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 thereof; (B) an organohydrogen polysiloxane that has at least two hydrogen atoms, each of which is directly bonded to a silicon atom, (C) a thermally conductive filler material comprising (C-1) a spherical alumina filler which has an average particle diameter of more than 65 [mu]m but not more than 135 [mu]m, (C-2) a spherical alumina filler which has an average particle diameter of more than 30 [mu]m but not more than 65 [mu]m, (C-3) a spherical alumina filler which has an average particle diameter of more than 4 [mu]m but not more than 30 [mu]m, and (C-4) an amorphous alumina filler which has an average particle diameter of more than 0.4 [mu]m but not more than 4 [mu]m; (D) a platinum group metal-based curing catalyst; and (E) an addition reaction control agent. Consequently, the present invention provides: a thermally conductive silicone composition which has excellent compressibility, insulation properties, thermal conductivity and workability; and a cured product thereof.

Description

Thermally conductive silicon oxide composition and its hardened product

The invention relates to a heat-conductive silicon-oxygen composition and its cured product.

Large-scale integrated circuit chips (LSI chips) such as central processing units (CPUs), driver integrated circuits (driver ICs) and memories used in electronic devices such as personal computers, digital audio-visual discs, and mobile phones, are accompanied by high Increased performance/higher speed/smaller size/higher integration itself generates a large amount of heat, and when the temperature of the wafer rises due to the heat, it may cause malfunction or destruction of the wafer. Therefore, many methods of dissipating heat and heat dissipating members used in the methods have been proposed to suppress the temperature rise of the wafer in operation.

Conventionally, in electronic equipment and the like, a heat sink made of a metal plate with high thermal conductivity such as aluminum or copper has been used in order to suppress a temperature rise of a chip in operation. The heat sink can conduct the heat generated by the chip, and release the heat from the surface through the temperature difference with the outside air.

In order to efficiently transfer the heat generated by the chip to the heat sink, it is necessary to make the heat sink closely adhere to the chip, but there are differences in the height of each chip or tolerances caused by assembly processing, so it is necessary to have a flexible sheet or heat sink. Paste mounts are interposed between the die and the heat sink so that heat conduction from the die to the heat sink is achieved through these components.

Compared with heat dissipation paste, the handling properties of the sheet are excellent, and the thermally conductive silicone rubber sheet (thermally conductive silicone rubber sheet) is used in various fields. For example, there has been disclosed an insulating composition in which 100 parts by mass of synthetic rubber such as silicone rubber is blended with at least one selected from the group consisting of beryllium oxide, aluminum oxide, aluminum hydroxide, magnesium oxide, and zinc oxide. obtained from metal oxides (Patent Document 1). On the other hand, the high integration of electronic devices has progressed, and the heat generated by the integrated circuit elements in the device has increased, so the conventional cooling method may not be sufficient. Especially, in the case of a portable notebook personal computer or a tablet computer, the space inside the machine is narrow, so it is impossible to install a large heat sink or a cooling fan. Furthermore, in these machines, integrated circuit elements are mounted on the printed circuit board, and glass-reinforced epoxy resin or polyimide resin with poor thermal conductivity is used as the material of the substrate. material to dissipate heat to the substrate.

Therefore, in such a case, a method of disposing a natural cooling type or a forced cooling type heat dissipation part near the integrated circuit element is used to transfer the heat generated by the element to the heat dissipation part. If the element is in direct contact with the heat dissipation part in this way, the heat transfer will be deteriorated due to the unevenness of the surface. Furthermore, even if the heat dissipation insulating sheet is installed via the heat dissipation insulating sheet, since the heat dissipation insulating sheet is slightly less flexible, stress may be applied between the element and the substrate due to thermal expansion, resulting in damage. In addition, a large space is required to mount heat dissipation components on each circuit element, making it difficult to downsize the device. Therefore, a method is sometimes adopted in which some elements are combined with a single heat dissipation part for cooling.

Therefore, there is a need for a low-hardness, high-thermal-conductivity material capable of filling various gaps generated by the height difference of each element. To address such a problem, a thermally conductive sheet is required that is excellent in thermal conductivity, has flexibility, and can cope with various gaps. At this time, a sheet is disclosed, which is formed by mixing a thermally conductive material such as a metal oxide into a silicone resin, and an easily deformable silicone layer is laminated on a strong silicone resin layer ( Patent Document 2). In addition, a thermally conductive composite sheet is disclosed, which is obtained by combining a silicone rubber layer and a porous reinforcing material layer, the silicone rubber layer contains a thermally conductive filler, and the Asker C hardness is 5 to 50, the porous The performance reinforcing material layer has holes with a diameter of 0.3 mm or more (Patent Document 3). In addition, a sheet material is also proposed, which is obtained by covering the surface of the skeleton lattice of a flexible three-dimensional network body or frame with thermally conductive silicone rubber (Patent Document 4). Further, a thermally conductive composite silicon oxide sheet is disclosed, which is built with a reinforcing sheet or fabric, at least one side of which has adhesiveness, Asker C hardness is 5-50, and the thickness of the sheet is 0.4mm or less (Patent Document 5). Moreover, a heat dissipation spacer is also disclosed, which contains addition reaction type liquid silicone rubber and thermally conductive insulating ceramic powder, the Asker C hardness of the cured product is 25 or less, and the thermal resistance is 3.0° C./W or less ( Patent Document 6).

Most of these thermally conductive silicone hardened products also require insulation, so alumina (alumina) is mostly used as a thermally conductive filler. Generally speaking, compared with spherical alumina, the effect of improving thermal conductivity of amorphous alumina is higher. However, it has the disadvantage that the filling property of polysiloxane is poor, and if the filling rate is increased, the viscosity of the material will increase and the workability will be deteriorated. In addition, alumina is very hard, having a hardness of 9 on the Mohs scale. Therefore, in particular, a thermally conductive silica composition using amorphous alumina having a particle size of 10 μm or more has a problem in that the inner wall of the reactor or the stirring blade is cut during production. As a result, the components of the reactor or the stirring blade are mixed into the thermally conductive silicon oxide composition, and the insulation of the thermally conductive silicon oxide composition and the cured product obtained by using the thermally conductive silicon oxide composition is reduced. In addition, since the gap between the reaction vessel and the stirring blade becomes wider, the stirring efficiency is lowered, and constant quality cannot be obtained even if it is manufactured under the same conditions. In addition, there is a problem that in order to prevent this, frequent replacement of components is required.

In order to solve this problem, there is also a method of using only spherical alumina powder, but in order to achieve high thermal conductivity, a large amount of filling is required compared with amorphous alumina, and the viscosity of the composition increases, which deteriorates workability. In addition, the amount of polysiloxane in the composition and its hardened product is relatively reduced, so the hardness will increase and the compressibility will deteriorate. There is also a method of improving the effect of improving the thermal conductivity relative to the filling amount by using spherical alumina with a large particle size, but there is a problem that if the particle size of the spherical alumina is too large, it will be difficult to Separation of the spherical alumina from the resin occurs, and the end of the sheet becomes embrittled as a filler-rich part. In this case, the material yield at the time of sheet forming is greatly reduced. In addition, in order to improve the thermal conductivity, there is a method of using a thermally conductive filler material with generally high thermal conductivity, such as aluminum nitride and boron nitride, but there are problems as follows: the cost is high, Processing is also more difficult. In addition, if the filling amount of alumina powder in the silicone hardened product is increased, the hardness of the cured product tends to decrease significantly when used at high temperature for a long time. Depending on the application such as a strong vibration module, there are the following problems: Poor adhesion occurs due to insufficient resilience, and thermal resistance increases with time. [Prior Art Literature] (patent documents)

Patent Document 1: Japanese Patent Application Laid-Open No. 47-032400 Patent Document 2: Japanese Patent Application Laid-Open No. 02-196453 Patent Document 3: Japanese Patent Application Laid-Open No. 07-266356 Patent Document 4: Japanese Patent Application Laid-Open No. 08-238707 Patent Document 5: Japanese Patent Application Laid-Open No. 09-001738 Patent Document 6: Japanese Patent Application Laid-Open No. 09-296114

[Problem to be solved by the invention]

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a thermally conductive silicon oxide composition and its cured product, which are excellent in compressibility, insulation, thermal conductivity, and processability. In particular, an object of the present invention is to provide a thermally conductive silicon oxide composition having a thermal conductivity of 5.5 W/m･K or higher and a cured product thereof. Such a thermally conductive silicone composition can be suitably used as, for example, a thermally conductive resin molded body that is placed between a heat-generating component and a heat-dissipating component in, for example, an electronic device to dissipate heat. [Technical means to solve the problem]

In order to achieve the above object, the present invention provides a thermally conductive silicon oxide composition, which includes: 100 parts by mass of (A) organopolysiloxane having at least 2 alkenyl groups in one molecule; (B) Organohydrogenpolysiloxanes having at least 2 hydrogen atoms directly bonded to silicon atoms, the amount of the component (B) being the number of moles of hydrogen atoms directly bonded to silicon atoms as the source The amount from 0.1 to 5.0 times the number of moles of the alkenyl group of the aforementioned (A) component; 3900-6000 parts by mass (C) of a thermally conductive filler comprising the following components (C-1) to (C-4), 1,400 to 3,000 parts by mass (C-1) of spherical alumina fillers with an average particle size of more than 65 μm and less than 135 μm, 500 to 1,500 parts by mass (C-2) of spherical alumina fillers with an average particle size of more than 30 μm and less than 65 μm, 300 to 900 parts by mass (C-3) of spherical alumina fillers with an average particle diameter of more than 4 μm and less than 30 μm, 1,000-1,900 parts by mass (C-4) of amorphous alumina fillers with an average particle size of more than 0.4 μm and less than 4 μm; (D) a platinum group metal-based hardening catalyst having an amount of 0.1 to 2000 ppm in terms of mass of the platinum group metal element relative to the aforementioned component (A); and, 0.01 to 2.0 parts by mass of (E) an addition reaction controller.

According to such a thermally conductive silicone composition, a thermally conductive silicone cured product having excellent compressibility, insulation, thermal conductivity, and workability can be obtained.

Also, in the present invention, it is preferable that the viscosity at 23°C is 2000 Pa･s or less.

Such a thermally conductive silicon oxide composition is excellent in formability (processability).

式(2)中，R ⁴獨立地為碳原子數1～6的烷基，c是5～100的整數。 Also, the present invention preferably further contains at least one member selected from the group consisting of the following components as the component (F) in an amount of 0.01 to 300 parts by mass relative to 100 parts by mass of the component (A): (F- 1) An alkoxysilane compound represented by the following general formula (1), R ¹ _a R ² _b Si(OR ³ ) _{4 - a - b} (1) In formula (1), R ¹ is independently a carbon atom An alkyl group with a number of 6 to 15, ^R2 is independently an unsubstituted or substituted monovalent hydrocarbon group with a carbon number of 1 to 12, ^R3 is an alkyl group with a carbon number of 1 to 6, and a is 1 to 6 an integer of 3, b is an integer of 0 to 2, and a+b is an integer of 1 to 3; and, (F-2) the single end of the molecular chain represented by the following general formula (2) is blocked by a trialkoxysilyl group Dimethicone,

In 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 such a heat-conducting silicone composition is used, oil separation will not be caused.

Moreover, it is preferable that this invention further contains 6.5-25.0 mass parts of cerium oxides which are (G) component with respect to 100 mass parts of said (A) components.

Such a thermally conductive silicon oxide composition improves heat resistance.

Also, the present invention provides a cured thermally conductive silicon oxide product, which is a cured product of the aforementioned thermally conductive silicon oxide composition.

Such a thermally conductive silicone cured product is excellent in compressibility, insulation, thermal conductivity, and workability.

In addition, the present invention is preferably: the above-mentioned thermally conductive silicon oxide cured product, wherein the hardness measured by the Asker C hardness meter is relative to the hardness before storage, and the hardness after storage at 150° C. for 500 hours is - 5 degrees or more and 40 degrees or less.

Such a thermally conductive silicon oxide cured product has a small decrease in hardness even if it is used at a high temperature for a long time.

Also, in the present invention, it is preferable that the thermal conductivity at 23° C. is 5.5 W/m･K or more.

Such a thermally conductive silicone cured product has excellent thermal conductivity.

Also, in the present invention, it is preferable that the dielectric breakdown voltage at a thickness of 1 mm is 10 kV/mm or more.

Such a thermally conductive silicon oxide cured product can stably ensure insulation during use.

Also, in the present invention, the shape may be a sheet.

Such a thermally conductive silicone cured product is excellent in handleability. [Efficacy of the invention]

The thermally conductive silicon oxide composition of the present invention is obtained by using in combination a spherical alumina filler with an average particle diameter of more than 65 μm and 135 μm, a spherical alumina filler with an average particle diameter of more than 30 μm and less than 65 μm, and an average particle diameter of Spherical alumina fillers with a diameter of more than 4 μm and less than 30 μm and amorphous alumina fillers with an average particle diameter of more than 0.4 μm and less than 4 μm, so that the large particle size spherical alumina can make up for the smaller particle size. Shortcomings, spherical alumina with smaller particle size makes up for the shortcomings of large particle size spherical alumina, thereby providing a thermally conductive silicon oxide composition that can obtain a compressibility, insulation, and Thermally conductive silicone hardened product that is excellent in thermal conductivity and processability, and especially has a thermal conductivity of 5.5W/m･K or higher. Furthermore, by adding cerium oxide, it is possible to provide a thermally conductive silicon oxide composition capable of obtaining a thermally conductive silicon oxide cured product that suppresses a decrease in hardness of the cured product during high-temperature storage.

As described above, it is desired to develop a thermally conductive silicon oxide composition and a cured product which are excellent in compressibility, insulation, thermal conductivity, and processability.

The inventors of the present invention have devoted themselves to research in order to achieve the above object. As a result, they have found that by using a specific ratio of spherical alumina and amorphous alumina with an average particle diameter of more than 0.4 μm and 65 μm or less, and an average particle diameter of more than 65 μm and 135 μm The following spherical alumina can solve the above-mentioned problems. That is, by setting a specific blending amount of spherical alumina with a small specific surface area and an average particle size of more than 65 μm and less than 135 μm, thermal conductivity can be effectively improved, and a low viscosity and excellent processability can be provided. Silicon oxide composition and its hardened products. In addition, by using together spherical alumina and amorphous alumina having an average particle diameter of 30 μm or less, the fluidity of the composition is improved and workability is improved. Furthermore, since spherical alumina is used as the particle whose average particle diameter exceeds 4 micrometers, abrasion of a reaction vessel or a stirring blade can be suppressed, and insulation improves.

That is, it was found that by making up for the disadvantages of spherical alumina and amorphous alumina with large particle diameters, the spherical alumina and amorphous alumina with small particle diameters compensated for the shortcomings of spherical alumina with large particle diameters. To overcome the disadvantages of alumina-like clay, a low-cost thermally conductive silicon oxide composition and hardened product can be obtained. The thermally conductive silicon oxide composition and hardened product are excellent in compressibility, insulation, thermal conductivity, and processability, and especially have Thermal conductivity above 5.5W/m･K.

Furthermore, it has also been found that by adding cerium oxide to the above-mentioned thermally conductive silicon oxide composition, the decrease in hardness of the cured product can be suppressed during high-temperature storage.

That is, the present invention is a thermally conductive silicon oxide composition comprising: 100 parts by mass of (A) organopolysiloxane having at least 2 alkenyl groups in one molecule; (B) Organohydrogenpolysiloxanes having at least 2 hydrogen atoms directly bonded to silicon atoms, the amount of the component (B) being the number of moles of hydrogen atoms directly bonded to silicon atoms as the source The amount from 0.1 to 5.0 times the number of moles of the alkenyl group of the aforementioned (A) component; 3900-6000 parts by mass (C) of a thermally conductive filler comprising the following components (C-1) to (C-4), 1,400 to 3,000 parts by mass (C-1) of spherical alumina fillers with an average particle size of more than 65 μm and less than 135 μm, 500 to 1,500 parts by mass (C-2) of spherical alumina fillers with an average particle size of more than 30 μm and less than 65 μm, 300 to 900 parts by mass (C-3) of spherical alumina fillers with an average particle diameter of more than 4 μm and less than 30 μm, 1,000-1,900 parts by mass (C-4) of amorphous alumina fillers with an average particle size of more than 0.4 μm and less than 4 μm; (D) a platinum group metal-based hardening catalyst having an amount of 0.1 to 2000 ppm in terms of mass of the platinum group metal element relative to the aforementioned component (A); and, 0.01 to 2.0 parts by mass of (E) an addition reaction controller.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to these descriptions.

The thermally conductive silicone composition of the present invention contains the following components as essential components: (A) organopolysiloxane having at least 2 alkenyl groups in one molecule; (B) organohydrogenpolysiloxane having at least 2 alkenyl groups; a hydrogen atom directly bonded to a silicon atom; (C) a thermally conductive filling material comprising the following components (C-1) to (C-4), (C-1) having an average particle diameter exceeding 65 μm and within 135 μm The following spherical alumina fillers, (C-2) spherical alumina fillers with an average particle diameter of more than 30 μm and less than 65 μm, (C-3) spherical alumina fillers with an average particle diameter of more than 4 μm and less than 30 μm, (C-4) Amorphous alumina filler having an average particle diameter of more than 0.4 μm and 4 μm or less; (D) platinum group metal-based hardening catalyst; (E) addition reaction control agent. In addition, components such as (F) a surface treatment agent, (G) cerium oxide, and (H) organopolysiloxane may be contained. Each component is described in detail below.

[(A) Organopolysiloxane having an alkenyl group] Organopolysiloxane having at least 2 alkenyl groups in one molecule of component (A) is used as the main ingredient of the thermally conductive silicone composition of the present invention, and it is an organopolysiloxane in one molecule It has two or more alkenyl groups bonded to silicon atoms. Usually, the main chain part is basically composed of repeating diorganosiloxane units, but the (A) component may include a branched structure in a part of the molecular structure, or may be a cyclic body, From the viewpoint of physical properties such as mechanical strength of the cured product, linear diorganopolysiloxane is preferred.

Examples of the functional group other than the alkenyl group bonded to the silicon atom include monovalent hydrocarbon groups exemplified below. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, Alkyl groups such as dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenyl, etc. Among these monovalent hydrocarbon groups, a group having 1 to 10 carbon atoms is preferable, and a group having 1 to 6 carbon atoms is more preferable. Among them, an alkyl group having 1 to 3 carbon atoms such as a methyl group, an ethyl group, and a propyl group; and a phenyl group can be preferably used. In addition, the functional groups other than the alkenyl group bonded to the silicon atom are not limited to all being the same.

Also, examples of the alkenyl group include alkenyl groups usually having about 2 to 8 carbon atoms such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, and cyclohexenyl. Among them, lower alkenyl groups such as vinyl and allyl are preferred, and vinyl is particularly preferred. In addition, there are two or more alkenyl groups in the molecule, and in order to improve the flexibility of the obtained cured product, it is preferable that the alkenyl groups exist only in the form of bonding to the silicon atom at the end of the molecular chain.

The kinetic viscosity of the organopolysiloxane having at least 2 alkenyl groups in the molecule is usually in the range of 10 to 100,000 mm ² /s, particularly preferably in the range of 500 to 50,000 mm ² /s at 23°C. If the aforementioned kinematic viscosity is within this range, the storage stability and ductility of the obtained composition will not deteriorate. In addition, in this specification, a dynamic viscosity is the value when it measures at 23 degreeC using the Canon-Vensk type viscometer according to the method of JISZ 8803:2011.

The organopolysiloxane having at least two alkenyl groups in one molecule of the component (A) may be used alone or in combination of two or more having different dynamic viscosities.

[(B) Organohydrogenpolysiloxane] The organohydrogenpolysiloxane of the component (B) is an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms. That is, an organohydrogenpolysiloxane having at least 2, preferably 2 to 100, hydrogen atoms (silylhydrogen groups) directly bonded to silicon atoms in one molecule, and used as component (A) A cross-linking agent is used to function as an ingredient. That is, the hydrosilyl group in the component (B) is added to the alkenyl group in the component (A) through a hydrosilylation reaction to obtain a three-dimensional network structure with a crosslinked structure. The hydrosilylation reaction is carried out by the following (D) The platinum group metal-based hardening catalyst of the component is promoted. Furthermore, when the number of silicon hydrogen groups is less than 2, it cannot be hardened.

式(3)中，R ⁵獨立地為氫原子、或選自碳數1～12的烷基、碳數6～12的芳基及碳數7～12的芳烷基中的一價烴基。其中，一分子中的至少2個、較佳是2～10個R ⁵為氫原子。e是1以上的整數，較佳是10～200的整數。 As the organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to the silicon atom, an organohydrogenpolysiloxane represented by the following average structural formula (3) can be used, but is not limited to this organohydrogen polysiloxane Polysiloxane.

In formula (3), R ⁵ is independently a hydrogen atom, or a monovalent hydrocarbon group selected from an alkyl group having 1 to 12 carbons, an aryl group having 6 to 12 carbons, and an aralkyl group having 7 to 12 carbons. Wherein, at least 2, preferably 2 to 10 R ⁵ in one molecule are hydrogen atoms. e is an integer of 1 or more, preferably an integer of 10-200.

In formula (3), R ⁵ is independently a hydrogen atom, or a monovalent hydrocarbon group selected from an alkyl group having 1 to 12 carbons, an aryl group having 6 to 12 carbons, and an aralkyl group having 7 to 12 carbons. Examples of monovalent hydrocarbon groups other than hydrogen atoms for ^R5 include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, and hexyl , heptyl, octyl, nonyl, decyl, dodecyl and other alkyl groups; cyclopentyl, cyclohexyl, cycloheptyl and other cycloalkyl groups; phenyl, tolyl, xylyl, naphthyl, biphenyl Aryl groups such as phenyl; Aralkyl groups such as benzyl, phenethyl, phenylpropyl, and methylbenzyl. Among these monovalent hydrocarbon groups, those with 1 to 10 carbon atoms are preferred, and those with 1 to 6 carbon atoms are particularly preferred. Among them, methyl, ethyl, propyl, and An alkyl group having 1 to 3 carbon atoms such as a group, and a phenyl group. Also, R ⁵ is not limited to all being the same. Moreover, e is an integer of 1 or more, Preferably it is an integer of 10-200.

The amount of component (B) to be added is such that the silanyl group derived from component (B) becomes 0.1 to 5.0 moles relative to 1 mole of alkenyl group derived from component (A), that is, it is directly bonded to silicon The number of moles of hydrogen atoms on the atom is 0.1 to 5.0 times the number of moles of the alkenyl group derived from the aforementioned (A) component, preferably 0.3 to 2.0 moles, and more preferably 0.5 ~ 1.0 molar amount. If the amount of Si-H groups derived from component (B) is less than 0.1 mol per 1 mol of alkenyl groups derived from component (A), hardening may not be possible, or the strength of the cured product may not be maintained. As the shape of a molded body, it cannot be manipulated. Moreover, if it exceeds 5 moles, the cured product will lose flexibility and become brittle.

[(C) Component: Thermally Conductive Filler] The component (C) is a thermally conductive filler, and includes the following components (C-1) to (C-4). (C-1) Spherical alumina fillers with an average particle diameter of more than 65 μm and less than 135 μm, (C-2) Spherical alumina fillers with an average particle size of more than 30 μm and less than 65 μm, (C-3) Spherical alumina fillers with an average particle diameter of more than 4 μm and less than 30 μm, (C-4) An amorphous alumina filler having an average particle diameter of more than 0.4 μm and 4 μm or less. Furthermore, in the present invention, the above-mentioned average particle diameter is the value of the cumulative average particle diameter (median diameter) based on the volume, which is the Microtrac MT3300EX particle size analyzer manufactured by Nikkiso Co., Ltd. according to Measured by laser diffraction/scattering method.

The spherical alumina filler of the composition (C-1) can advantageously improve thermal conductivity. The average particle diameter of the spherical alumina filler is more than 65 μm and less than 135 μm, preferably 70-120 μm. When the average particle diameter of the spherical alumina filler of the component (C-1) exceeds 135 μm, the abrasion of the reaction vessel or the stirring blade becomes remarkable, and the insulation of the composition decreases. As the spherical alumina of the component (C-1), one type may be used or two or more types may be used in combination. When two or more kinds are used in combination, each of them should just satisfy the range of the above-mentioned average particle diameter.

The spherical alumina fillers of the components (C-2) and (C-3) can increase the thermal conductivity of the composition, and suppress the contact between the amorphous alumina fillers and the reactor or stirring blades, and provide a barrier effect for suppressing wear. Regarding the average particle size, the component (C-2) is more than 30 μm to 65 μm, preferably 35 to 60 μm, and the component (C-3) is more than 4 μm to 30 μm, preferably 7 to 25 μm. If the average particle size of the spherical alumina filler is 4 μm or less, the barrier effect will decrease, and the wear of the reactor or the stirring blade due to the amorphous particles will become significant. As the spherical alumina of the component (C-2) and the component (C-3), one type may be used or two or more types may be used in combination. When two or more kinds are used in combination, each of them should just satisfy the range of the above-mentioned average particle diameter.

The amorphous alumina filler of the component (C-4) is also responsible for improving the thermal conductivity of the composition, but its main function is to adjust the viscosity of the composition, improve the smoothness, and improve the filling property. (C-4) The average particle diameter of the component exceeds 0.4 micrometers and is 4 micrometers or less, in order to express the said characteristic, it is more preferable that it is 0.6-3 micrometers.

The compounding quantity of (C-1) component is 1400-3000 mass parts with respect to 100 mass of (A) components, Preferably it is 1800-2500 mass parts. If the compounding amount of (C-1) component is too small, it will become difficult to improve thermal conductivity, and if it is too large, the abrasion of a reaction vessel or a stirring blade will become remarkable, and the insulation of a composition will fall.

The compounding quantity of (C-2) component is 500-1500 mass parts with respect to 100 mass of (A) components, Preferably it is 600-1300 mass parts. If the blending amount of the component (C-2) is too small, the abrasion of the reaction vessel or the stirring blade due to the amorphous particles will become significant, and if it is too large, the composition will lose fluidity and formability will be impaired.

The compounding quantity of (C-3) component is 300-900 mass parts with respect to 100 mass parts of (A) components, Preferably it is 500-800 mass parts. If the blending amount of the component (C-3) is too small, the abrasion of the reaction vessel or the stirring blade due to the amorphous particles will become significant, and if it is too large, the composition will lose fluidity and impair the formability.

The compounding quantity of (C-4) component is 1000-1900 mass parts with respect to 100 mass parts of (A) components, Preferably it is 1100-1500 mass parts. If the blending amount of the component (C-4) is too small, the composition loses fluidity and moldability is impaired. When the compounding quantity of (C-4) component is too large, abrasion of a reaction tank or a stirring blade will become remarkable.

Furthermore, the compounding quantity of (C) component (namely, the total compounding quantity of said (C-1) component - (C-4) component) is 3900-6000 mass parts with respect to 100 mass parts of (A) component , preferably 4000 to 5500 parts by mass. When the blending amount is less than 3900 parts by mass, the thermal conductivity of the obtained composition deteriorates, and when it exceeds 6000 parts by mass, the composition loses fluidity and impairs formability.

By using (C)component in the said blending ratio, the effect of this invention mentioned above can be achieved more advantageously and reliably.

[(D) Platinum Group Metal-Based Hardening Catalyst] The platinum-group metal-based hardening catalyst of component (D) is used to accelerate the addition of alkenyl group derived from component (A) and silylhydrogen group derived from component (B). As the catalyst for the formation reaction, known catalysts can be cited as the catalyst used for the hydrosilylation reaction. Specific examples thereof include simple platinum group metals such as platinum (including platinum black), rhodium, and palladium; H ₂ PtCl ₄ ･nH ₂ O, H ₂ PtCl ₆ ･nH ₂ O, NaHPtCl ₆ ･nH ₂ O , KaHPtCl 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 (wherein, in the above formula , n is an integer of 0 to 6, preferably 0 or 6) platinum chloride, chloroplatinic acid and chloroplatinate; alcohol modified chloroplatinic acid (refer to US Patent No. 3220972 instructions), chloroplatinic acid Complexes with olefins (refer to US Patent No. 3159601 specification, US Patent No. 3159662 specification, and US Patent No. 3775452 specification); platinum black, palladium, etc. are supported on alumina, silicon dioxide, carbon, etc. Substances derived from platinum group metals; rhodium-olefin complexes; chlorinated ginseng (triphenylphosphine) rhodium (Wilkinson catalyst); platinum chloride, chloroplatinic acid or chloroplatinate and vinyl-containing Siloxanes, especially complexes of vinyl-containing cyclic siloxanes, etc.

(D) The compounding quantity of a component is 0.1-2000 ppm with respect to the mass conversion of a platinum group metal element with respect to (A) component, Preferably it is 50-1000 ppm. If there is too little compounding quantity of (D)component, an addition reaction will not progress, and since it is economically disadvantageous if too much, it is unfavorable.

[(E) Addition reaction control agent] As the addition reaction control agent of the component (E), all known addition reaction control agents used in general addition reaction hardening type silicone compositions can be used. Examples include: acetylene compounds such as 1-ethynyl-1-hexanol, 3-butyn-1-ol, ethynylmethine carbitol, etc.; or various nitrogen compounds; organophosphorus compounds; oxime compounds; Chlorine compounds, etc.

The compounding quantity of (E) component is 0.01-2.0 mass parts with respect to 100 mass parts of (A) components, Preferably it is 0.1-1.2 mass parts. If the blending amount of the component (E) is too small, the handleability of the composition may deteriorate due to the progress of the addition reaction, and if too large, the addition reaction may not progress, impairing the molding efficiency.

[(F) Surface treatment agent] In the thermally conductive silicon oxide composition of the present invention, when preparing the composition, a surface treatment agent of (F) component can be blended for the purpose of hydrophobizing the thermally conductive filler as component (C), Improve the wettability with the alkenyl-containing organopolysiloxane as component (A), and uniformly disperse the thermally conductive filler as component (C) in the matrix composed of component (A). Although it does not specifically limit as this (F) component, Especially preferable are (F-1) component and (F-2) component shown below.

Component (F-1) is an alkoxysilane compound represented by the following general formula (1). R ¹ _a R ² _b Si(OR ³ ) _{4 - a - b} (1) In formula (1), R ¹ is independently an alkyl group having 6 to 15 carbon atoms, and R ² is independently unsubstituted or substituted A substituted monovalent hydrocarbon group with 1 to 12 carbon atoms, ^R3 is independently an alkyl group with 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 1 to 3 an integer of .

In the above general formula (1), examples of the alkyl group represented by R ¹ include hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl and the like. If the number of carbon atoms of the alkyl group represented by ^R1 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 become good.

The unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms represented by ^R is preferably selected from alkyl groups having 1 to 5 carbon atoms, aryl groups having 6 to 12 carbon atoms, and A group in an aralkyl group having 7 to 12 carbon atoms. Examples of the alkyl group having 1 to 5 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tertiary butyl group, pentyl group and neopentyl group. Examples of the aryl group having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, naphthyl, biphenyl and the like. Furthermore, examples of the aralkyl group having 7 to 12 carbon atoms include benzyl group, phenethyl group, phenylpropyl group, methylbenzyl group and the like. Among them, alkyl groups having 1 to 3 carbon atoms such as methyl group, ethyl group, and propyl group; and phenyl group are preferable. Examples of the alkyl group having 1 to 6 carbon atoms represented by R ³ include methyl, ethyl, propyl, butyl, hexyl and the like.

式(2)中，R ⁴獨立地為碳原子數1～6的烷基，c是5～100的整數。 Component (F-2) is a dimethyl polysiloxane whose one end of the molecular chain is blocked by a trialkoxysilyl group, which is represented by the following general formula (2).

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

Examples of the alkyl group having 1 to 6 carbon atoms represented by R ⁴ include, for example, the same groups as the alkyl groups exemplified for R ³ above. c is an integer of 5-100, preferably an integer of 5-70, particularly preferably an integer of 10-50.

As a surface treatment agent of (F) component, at least 1 sort(s) chosen from the group which consists of (F-1) component and (F-2) component can be blended. As a compounding quantity at the time of blending (F) component, Preferably it is 0.01-300 mass parts with respect to 100 mass parts of (A) components, More preferably, it is 0.1-200 mass parts. Oil separation will not occur as the compounding quantity of (F)component is below the said upper limit.

[(G) Cerium Oxide] Cerium oxide can be blended as the (G) component in the thermally conductive silicon oxide composition of the present invention. Cerium oxide as a component (G) is a heat stabilizer that improves heat resistance. As cerium oxide, it is preferable to use cerium oxide having a Buert (BET) specific surface area of 50 m ² /g or more.

The compounding quantity of (G)component is 6.5-25.0 mass parts with respect to 100 mass parts of (A) components, More preferably, it is 8.0-13.0 mass parts. When the blending amount of the component (G) is within the above range, the hardness of the hardened product does not decrease during high-temperature storage, the composition does not lose fluidity, and the formability is not impaired.

式(4)中，R ⁶獨立地為未被取代或經取代的碳原子數1～12的不包含脂肪族不飽和鍵之一價烴基，d是5～2000的整數。 [(H) Organopolysiloxane] In the thermally conductive silicone composition of the present invention, for the purpose of imparting properties such as a viscosity modifier of the thermally conductive silicone composition, the following components can be added as the (H) component: The organopolysiloxane represented by the general formula (4), wherein the organopolysiloxane has a kinematic viscosity at 23° C. of 10 to 100,000 mm ² /s. (H) The component may be used individually by 1 type, and may use 2 or more types together.

In formula (4), R ⁶ is independently an unsubstituted or substituted C1-12 valent hydrocarbon group not containing an aliphatic unsaturated bond, and d is an integer of 5-2000.

In the above general formula (4), R ⁶ is independently an unsubstituted or substituted valent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond. Examples of R ⁶ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl Alkyl groups such as , decyl, and dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenyl; Aralkyl groups such as benzyl, phenethyl, phenylpropyl, and methylbenzyl; and halogens such as fluorine, chlorine, bromine, etc., in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are replaced Atoms, cyano groups, etc., 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, particularly representative groups are carbon A group with 1 to 6 atoms, preferably: the number of carbon atoms of methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, cyanoethyl, etc. Unsubstituted or substituted alkyl groups of 1 to 3; and unsubstituted or substituted phenyl groups such as phenyl, chlorophenyl, and fluorophenyl; more preferably methyl and phenyl. The aforementioned d is preferably an integer of 5 to 2000, more preferably an integer of 10 to 1000, from the viewpoint of the required viscosity.

In addition, the kinematic viscosity of the component (H) at 23° C. is preferably from 10 to 100,000 mm ² /s, more preferably from 100 to 10,000 mm ² /s. If the kinematic viscosity is 10 mm ² /s or more, the obtained thermally conductive silicone cured product will not suffer from oil bleeding. If the dynamic viscosity is 100000 mm ² /s or less, the obtained thermally conductive silicone cured product will have sufficient flexibility.

When the (H) component is blended into the thermally conductive silicon oxide composition of the present invention, its blending amount is not limited, as long as it is an amount that can obtain the desired effect, with respect to 100 parts by mass of the (A) component, Preferably it is 0.1-100 mass parts, More preferably, it is 1-50 mass parts. If the added amount is within this range, it is easy to maintain good fluidity and workability for the thermally conductive silicon oxide composition before curing, and it is easy to fill the composition with the thermally conductive filler of component (C).

[other ingredients] In the thermally conductive silicon oxide composition of the present invention, other components may be further blended according to the purpose and effects of the present invention. For example, any of the following components can be blended: a heat resistance enhancer such as iron oxide; a viscosity adjuster such as silica; a colorant; a mold release agent and the like.

[Viscosity of thermally conductive silicon oxide composition] The viscosity (absolute viscosity) of the thermally conductive silicone composition of the present invention is preferably 2000 Pa･s or less at 23°C, more preferably 1500 Pa･s or less. The lower limit of the viscosity is not particularly limited, and can be, for example, 100 Pa·s or more. When the viscosity is 2000 Pa･s or less, the formability (processability) of the composition will not be impaired. Furthermore, in the present invention, the viscosity is based on the measurement performed by a flow tester viscometer.

[Preparation of thermally conductive silicon oxide composition] The thermally conductive silicon oxide composition of the present invention can be prepared by uniformly mixing the above components according to a conventional method.

[Thermal Conductive Silicone Curing] The thermally conductive silicone cured product of the present invention is obtained by curing the above-mentioned thermally conductive silicone composition of the present invention according to a conventional method. The shape of the thermally conductive silicone cured product of the present invention is not particularly limited, but is preferably a sheet shape.

[Manufacturing method of thermally conductive silicone hardened product] The curing conditions for molding the thermally conductive silicone composition can be the same as that of the known addition reaction curing silicone rubber composition. For example, it can be sufficiently cured at room temperature, or it can be heated if necessary. Preferably, the addition hardening is carried out at 100-120° C. for 8-12 minutes. The thermally conductive silicone cured product of the present invention thus obtained is excellent in thermal conductivity.

[Thermal conductivity of thermally conductive silicone cured product] The thermal conductivity of the thermally conductive silicone cured product of the present invention is preferably at least 5.5 W/m･K measured at 23°C, more preferably at least 6.0 W/m･K. The higher the thermal conductivity, the better, and the upper limit is not particularly limited, and can be, for example, 8.0 W/m･K or less. In addition, in this invention, thermal conductivity is based on the measurement by the hot disk (Hot Disk) method.

[Dielectric breakdown voltage of thermally conductive silicone cured products] The dielectric breakdown voltage of the thermally conductive silicon oxide cured product of the present invention is a measured value when measuring the dielectric breakdown voltage of a molded body with a thickness of 1 mm in accordance with Japanese Industrial Standard (JIS) K 6249, and is preferably 10 kV or more, more preferably The best is above 12kV. The upper limit of the dielectric breakdown voltage is not particularly limited, and can be, for example, 20 kV/mm or less. In the case of a sheet having a dielectric breakdown voltage of 10 kV/mm or more, insulation can be stably ensured during use. Furthermore, such a dielectric breakdown voltage can be adjusted by adjusting the type or purity of the filler.

[Hardness of thermally conductive silicone hardened product] The hardness of the thermally conductive silicon oxide cured product in the present invention is preferably 60 or less, more preferably 40 or less, and more preferably 30 or less, as measured by an Asker C hardness meter at 23°C. And, it is preferably 5 or more. When the hardness is 60 or less, it becomes easy to deform according to the shape of the heat sink, and exhibits good heat radiation characteristics without stressing the heat sink. Furthermore, such hardness can be adjusted by adjusting the crosslink density by changing the ratio of (A) component and (B) component. When the hardness is low, the compressibility is excellent.

The thermally conductive silicon oxide cured product in the present invention is preferably such that the hardness measured by the Asker C hardness meter is relative to the hardness before storage, and the hardness after storage at 150°C for 500 hours is -5 degrees or more and 40 degrees. Degree or less; more preferably, the degree of decrease in Asker C hardness after storage at 150°C for 500 hours is less than 5 degrees. If the decline in Asker C hardness of the thermally conductive silicon oxide hardened product is less than 5 degrees, the hardened product will have a small decrease in hardness even if it is used at high temperature for a long time. The hardness before storage is measured by using a compression molding machine to harden the thermally conductive silicon oxide composition into a 6mm thick sheet at 120°C for 10 minutes, and stacking two sheets of this sheet with an Asker C hardness tester value. [Example]

Examples and comparative examples are shown below to describe the present invention concretely, but the present invention is not limited to the following examples. Furthermore, the dynamic viscosity is measured by a Canon-Vensk viscometer at 23°C. In addition, the average particle diameter is the value of the cumulative average particle diameter (median diameter) based on the volume, which is obtained by the particle size analyzer manufactured by Nikkiso Co., Ltd., Microtrac MT3300EX, according to laser diffraction/scattering measured by the law.

式(5)中，X是乙烯基，f是能夠得到上述黏度的數。 The components (A) to (G) used in the following examples and comparative examples are as follows. (A) Component: The following two types of organopolysiloxanes having alkenyl groups. (A-1): An organopolysiloxane having a kinematic viscosity represented by the following formula (5) of 600 mm ² /s. (A-2): An organopolysiloxane having a kinematic viscosity represented by the following formula (5) of 30000 mm ² /s.

In formula (5), X is a vinyl group, and f is a number which can obtain the said viscosity.

式(6-1)中，g是27，h是3，括弧內的矽氧烷單元的排列順序不固定。 (B-2)：由下述式(6-2)表示的有機氫聚矽氧烷。

式(6-2)中，g是18。 (B) Component: the following two types of organohydrogenpolysiloxanes. (B-1): An organohydrogenpolysiloxane represented by the following formula (6-1).

In the formula (6-1), g is 27, h is 3, and the arrangement order of the siloxane units in the brackets is not fixed. (B-2): An organohydrogenpolysiloxane represented by the following formula (6-2).

In formula (6-2), g is 18.

(C) Component: Spherical alumina and amorphous alumina having an average particle diameter as described below. (C-1): Spherical alumina with an average particle diameter of 88.6 μm. (C-2): Spherical alumina having an average particle diameter of 48.7 μm. (C-3): Spherical alumina with an average particle diameter of 16.7 μm. (C-4): Amorphous alumina having an average particle diameter of 1.7 μm. (D) Component: 2-ethylhexanol solution of 5% by mass of chloroplatinic acid. (E) Component: Ethynyl methine carbitol.

Component (F): Dimethicone represented by the following formula (7) whose one end is blocked with a trimethoxysilyl group, and whose average degree of polymerization is 30.

(G) Component: cerium oxide powder having a BET specific surface area of 140 m ² /g.

[Examples 1-5, Comparative Examples 1-2] In Examples 1 to 5 and Comparative Examples 1 to 2, a thermally conductive silicon oxide composition was prepared in the following manner using the prescribed amounts of the above-mentioned (A) to (G) components shown in Table 1, according to the following Method to measure the viscosity of thermally conductive silicon oxide composition. The thermally conductive silicon oxide composition was formed and cured, and the thermal conductivity, dielectric breakdown voltage, and hardness of the obtained thermally conductive silicon oxide cured product were measured according to the following methods. The results are shown in Table 1.

[Preparation of thermally conductive silicon oxide composition] Components (A), (C), (F), and (G) are added in the prescribed blending amounts shown in Examples 1 to 5 and Comparative Examples 1 to 2 in the following Table 1, and are carried out with a planetary mixer. Knead for 60 minutes. To this was added the specified amount of (D) component shown in Examples 1 to 5 and Comparative Examples 1 to 2 in the following Table 1, and further added an effective amount of phenyl-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd., that is, KF -54 (trade name) was added as a release agent to promote release from the separator, and kneaded for 30 minutes. To this was further added predetermined amounts of (B) component and (E) component shown in Examples 1 to 5 and Comparative Examples 1 to 2 in Table 1 below, and kneaded for 30 minutes to obtain a thermally conductive silicon oxide composition. things.

[assessment method] Viscosity of thermally conductive silicone composition: The viscosities of the thermally conductive silicone compositions obtained in Examples 1-5 and Comparative Example 1 were measured at 23° C. using a flow tester viscometer. As a measuring device, CFT-500EX (trade name) manufactured by Shimadzu Corporation was used. Set the mold hole diameter to φ2mm, the mold length to 2mm, and the test load to 10kg to draw a graph of time and stroke, and calculate the viscosity according to the slope.

Thermal conductivity: Using a press molding machine, the thermally conductive silicone compositions obtained in Examples 1 to 5 and Comparative Example 1 were cured into a sheet with a thickness of 6 mm at 120°C for 10 minutes, and two sheets were used , The thermal conductivity of the sheet was measured by a thermal conductivity meter (trade name: TPS-2500S, manufactured by Kyoto Electronics Industry Co., Ltd.).

Dielectric breakdown voltage: Using a press molding machine, the thermally conductive silicon oxide compositions obtained in Examples 1 to 5 and Comparative Example 1 were hardened into a sheet with a thickness of 1 mm under the conditions of 120°C and 10 minutes, and the medium was measured according to JIS K 6249. Electrode destruction voltage.

hardness: In the same manner as above, the thermally conductive silicone composition obtained in Examples 1 to 5 and Comparative Example 1 was cured into a sheet with a thickness of 6 mm, and two sheets of the sheet were stacked, and then tested with the Asker C hardness tester. Determination.

Hardness after storage at 150°C for 500 hours: After storing the thermally conductive silicon oxide cured sheet after the above-mentioned hardness measurement in a high-temperature furnace at 150° C. for 500 hours, two sheets of the sheet were stacked and measured with an Asker C hardness meter.

表1中，將有機氫聚矽氧烷中的直接鍵結於矽原子上的氫原子總量相對於具有烯基之有機聚矽氧烷中的烯基總量設為H/Vi。 [Table 1]

In Table 1, the total amount of hydrogen atoms directly bonded to silicon atoms in the organohydrogenpolysiloxane is H/Vi relative to the total amount of alkenyl groups in the organopolysiloxane having alkenyl groups.

In Examples 1 to 5, the viscosity of the thermally conductive silicon oxide composition, the thermal conductivity, the dielectric breakdown voltage, and the hardness of the thermally conductive silicon oxide hardened product are all good results. In Example 5, no cerium oxide was added, and it had sufficient hardness even when stored at a high temperature of 150°C. Also, when cerium oxide was added (Examples 1 to 4), no decrease in hardness was observed even when stored at a high temperature of 150°C. As shown in Comparative Example 1, if the component (C-2) is not contained and the total mass parts of the thermally conductive filler is less than 3900 parts by mass, the filler filling rate in the thermally conductive silicone cured product becomes small, and the thermal conductivity decreases. Also, as shown in Comparative Example 2, when the total mass parts of the thermally conductive filler exceeds 6000 parts by mass, the wettability of the thermally conductive silicone composition is insufficient, and a uniform grease-like thermally conductive silicone composition cannot be obtained. In addition, in Examples 1 to 5, the viscosity of the thermally conductive silicon oxide composition was about 300 to 600 Pa·s, and the processability was excellent. On the other hand, in Comparative Example 1, the viscosity was 200 Pa･s, and the processability was poor, and in Comparative Example 2, it could not be made into a grease. Furthermore, in Examples 1-5, hardness was 13-15, and it was excellent in compressibility. On the other hand, in Comparative Example 1, the hardness was 11 and the compressibility was poor, and in Comparative Example 2, measurement was not possible.

In addition, this invention is not limited to the said embodiment. The above-mentioned embodiments are examples, and any one having substantially the same configuration as the technical idea described in the claims of the present invention and exerting the same effects is included in the technical scope of the present invention.

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Claims (11)

A thermally conductive silicon oxide composition, characterized in that it comprises: 100 parts by mass of (A) organopolysiloxane having at least 2 alkenyl groups in one molecule; (B) Organohydrogenpolysiloxanes having at least 2 hydrogen atoms directly bonded to silicon atoms, the amount of the component (B) being the number of moles of hydrogen atoms directly bonded to silicon atoms as the source The amount from 0.1 to 5.0 times the number of moles of the alkenyl group of the aforementioned (A) component; 3900-6000 parts by mass (C) of a thermally conductive filler comprising the following components (C-1) to (C-4), 1,400 to 3,000 parts by mass (C-1) of spherical alumina fillers with an average particle size of more than 65 μm and less than 135 μm, 500 to 1,500 parts by mass (C-2) of spherical alumina fillers with an average particle size of more than 30 μm and less than 65 μm, 300 to 900 parts by mass (C-3) of spherical alumina fillers with an average particle diameter of more than 4 μm and less than 30 μm, 1,000-1,900 parts by mass (C-4) of amorphous alumina fillers with an average particle size of more than 0.4 μm and less than 4 μm; (D) a platinum group metal-based hardening catalyst having an amount of 0.1 to 2000 ppm in terms of mass of the platinum group metal element relative to the aforementioned component (A); and, 0.01 to 2.0 parts by mass of (E) an addition reaction controller. The thermally conductive silicon oxide composition according to claim 1, wherein the viscosity at 23°C is 2000 Pa･s or less. The thermally conductive silicon oxide composition according to claim 1, further comprising 0.01 to 300 parts by mass of the component (F) selected from the group consisting of the following components with respect to 100 parts by mass of the component (A) At least one of the group: (F-1) An alkoxysilane compound represented by the following general formula (1), R ¹ _a R ² _b Si(OR ³ ) _{4 - a - b} (1) Formula (1) Among them, R ¹ is independently an alkyl group with 6 to 15 carbon atoms, R ² is independently an unsubstituted or substituted monovalent hydrocarbon group with 1 to 12 carbon atoms, and R ³ is independently an alkyl group with 1 to 12 carbon atoms. An alkyl group of 6, 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; and, (F-2) a molecular chain unit represented by the following general formula (2) Dimethylpolysiloxane whose ends are blocked by trialkoxysilyl groups,

In 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 silicon oxide composition according to claim 2, further comprising 0.01 to 300 parts by mass of the component (F) selected from the group consisting of the following components relative to 100 parts by mass of the component (A) At least one of the group: (F-1) An alkoxysilane compound represented by the following general formula (1), R ¹ _a R ² _b Si(OR ³ ) _{4 - a - b} (1) Formula (1) Among them, R ¹ is independently an alkyl group with 6 to 15 carbon atoms, R ² is independently an unsubstituted or substituted monovalent hydrocarbon group with 1 to 12 carbon atoms, and R ³ is independently an alkyl group with 1 to 12 carbon atoms. An alkyl group of 6, 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; and, (F-2) a molecular chain unit represented by the following general formula (2) Dimethylpolysiloxane whose ends are blocked by trialkoxysilyl groups,

In 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 silicon oxide composition according to any one of claims 1 to 4, further comprising 6.5 to 25.0 parts by mass of cerium oxide as the component (G) relative to 100 parts by mass of the component (A). A thermally conductive silicon oxide cured product, characterized in that it is a cured product of the thermally conductive silicon oxide composition described in any one of Claims 1-5. The thermally conductive silicon oxide cured product according to claim 6, wherein the hardness measured by the Asker C hardness meter is relative to the hardness before storage, and the hardness after storage at 150°C for 500 hours is -5 degrees or higher And below 40 degrees. The thermally conductive silicon oxide cured product according to claim 6, wherein the thermal conductivity at 23°C is 5.5 W/m･K or more. The thermally conductive silicon oxide cured product according to claim 7, wherein the thermal conductivity at 23°C is 5.5 W/m･K or more. The thermally conductive silicon oxide cured product according to claim 6, wherein the dielectric breakdown voltage at a thickness of 1 mm is 10 kV/mm or more. The thermally conductive silicon oxide cured product described in claim 6 is in the form of a sheet.