JP2019182980A - Thermally-conductive silicone composition, and cured product of the same - Google Patents

Abstract

Provided are a thermally conductive silicone composition having excellent flame retardancy and heat resistance, and a cured product of the composition. A thermally conductive silicone composition containing (A) to (D). (A) An organopolysiloxane having a kinematic viscosity at 25 ° C of 500 to 1,000,000 mm2 / s represented by the following average composition formula: 100 parts by mass, (R13SiO1 / 2) a (R12SiO2 / 2) b ( R1SiO3 / 2) c (SiO4 / 2) d (R2O1 / 2) e (B) A linear organopolysiloxane having at least two alkenyl groups having 2 to 6 carbon atoms in one molecule. The ratio of the SiH groups in the component (A) to the alkenyl groups in the organopolysiloxanes (A) and (B), in which 40 to 70% of the total number of organic groups to be bonded are phenyl groups, is 0.5 to 2; , (C) a thermally conductive filler: 100 to 3500 parts by mass, (D) a hydrosilylation catalyst. [Selection diagram] None

Description

  The present invention relates to a thermally conductive silicone composition having thermoplasticity and a cured product thereof.

  In recent years, LSIs such as CPUs and memories used in electronic devices such as personal computers, communication devices, and medical devices have increased power consumption and heat generation as the degree of integration has increased and the operation speed has increased. Yes. Since this heat causes failure or malfunction of electronic equipment, heat dissipation measures that effectively dissipate heat are important.

  2. Description of the Related Art Conventionally, in an electronic device or the like, a method of directly transferring heat to a heat sink using a metal having high thermal conductivity such as aluminum, copper, brass or the like is used to suppress the temperature rise of electronic components. The heat sink conducts heat generated from the electronic component, and releases the heat from the surface due to a temperature difference from the outside air. In order to efficiently transfer heat generated from the electronic component to the heat sink, the heat sink and the electronic component must be in close contact with each other without any gaps. A flexible low-hardness thermal conductive sheet or thermal conductive grease is used between the electronic component and the heat sink. Is intervened.

However, since the heat conductive silicone rubber sheet used conventionally has a contact thermal resistance at the interface with the electronic component, there is a limit to the heat transfer performance.

  In recent years, from the viewpoint of work efficiency, a phase change type heat radiation sheet (phase change sheet) that is solid at room temperature and softens by heat has been proposed. This is a heat-dissipating material with excellent handling that can be mounted freely by applying heat to the electronic components and heat sink by preparing a sheet in advance, and the interface with the electronic components by being softened by heat. The contact thermal resistance is negligible, and exhibits superior heat dissipation performance compared to conventional thermal conductive sheets.

  Various phase change seats have been proposed so far. As a prior art of these phase change sheets, for example, Japanese Translation of PCT International Publication No. 2000-509209 (Patent Document 1) discloses heat conduction comprising an acrylic pressure-sensitive adhesive, an α-olefin thermoplastic, and a thermally conductive filler. Or a thermally conductive material composed of paraffin wax and a thermally conductive filler is described. Japanese Unexamined Patent Application Publication No. 2000-336279 (Patent Document 2) describes a heat conductive composition comprising a thermoplastic resin, a wax, and a heat conductive filler.

  However, these are all based on organic substances, and are not materials that are flame retardant. When these members are incorporated in an automobile or the like, deterioration due to high temperatures is a concern.

  On the other hand, silicone is known as a material excellent in heat resistance, weather resistance, and flame retardancy, and many similar heat-softening materials based on silicone have been proposed. As an example, JP 2000-327917 A (Patent Document 3) describes a composition comprising a thermoplastic silicone resin, a wax-like modified silicone resin, and a thermally conductive filler.

  However, since these compositions contain organic substances such as wax and wax modified with silicone in addition to silicone, there is a drawback that they are inferior in flame retardancy and heat resistance as compared with silicone alone.

  As a material having improved flame retardancy and heat resistance, Japanese Patent Application Laid-Open No. 2007-150349 (Patent Document 4) describes a heat dissipating member made of a thermoplastic silicone resin and a heat conductive filler. The heat dissipating member provided a molded product as a sheet and was mounted on an electronic component or a heat sink.

Special Table 2000-509209 JP 2000-336279 A JP 2000-327917 A JP 2007-150349 A

  However, the silicone resin described in Patent Document 4 has good workability when assembled to a large part, but has a drawback of poor workability when used for a small electronic part.

  The present invention has been made in view of the above circumstances, and is a silicone composition having thermal conductivity excellent in flame retardancy and heat resistance, crosslinked by hydrosilylation reaction, solid at room temperature, and softened at high temperature Or it aims at providing the hardened | cured material which liquefies. Furthermore, it aims at providing the heat conductive silicone composition easy to apply to a small electronic component and a heat sink.

  The present invention includes the following (A) component and (B) component that have been intensively studied to solve the above-mentioned problems and specified the phenyl group content, and (C) a thermally conductive filler and (D) a hydrosilylation catalyst. It has been found that a cured product obtained by curing a thermally conductive silicone composition is solid at room temperature and is significantly softened or liquefied at a high temperature, thus achieving the present invention.

That is, this invention provides the heat conductive silicone composition containing the following (A) component-(D) component, and the hardened | cured material of this composition.
(A) Organopolysiloxane having a kinematic viscosity of 500 to 1,000,000 mm ² / s at 25 ° C. represented by the average composition formula (1): 100 parts by mass
(R ¹ ₃ SiO _1/2 ) _a (R ¹ ₂ SiO _2/2 ) _b (R ¹ SiO _3/2 ) _c (SiO _4/2 ) _d (R ² O _1/2 ) _e
(1)
(In the formula, R ¹ is independently of each other a phenyl group, an alkyl group or a cycloalkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a hydrogen atom, provided that the total number of R ¹ is 50-80% of them are phenyl groups, 10-20% of the total number of R ¹ are hydrogen atoms, 0-20% of the total number of R ¹ are alkenyl groups, and R ² is hydrogen. It is an atom or an alkyl group having 1 to 6 carbon atoms, and a, b, c, d and e are 0 ≦ a ≦ 0.2, 0.2 ≦ b ≦ 0.7, 0.2 ≦ c ≦ 0. (6, 0 ≦ d ≦ 0.2, 0 ≦ e ≦ 0.1, and a + b + c + d = 1)
(B) A linear organopolysiloxane having at least two alkenyl groups having 2 to 6 carbon atoms in one molecule, and 40 to 70% of the total number of organic groups bonded to silicon atoms is a phenyl group The amount of the ratio of the number of SiH groups in the component (A) to the total number of alkenyl groups in the organopolysiloxane (A) component and the component (B) is 0.5 to 2,
(C) Thermally conductive filler: 100-3500 parts by mass, and (D) hydrosilylation catalyst.

  The thermally conductive silicone composition of the present invention can provide a thermoplastic cured product, which is a solid (soft rubber) at room temperature and softens or liquefies at a high temperature (for example, 100 ° C.). The thermally conductive silicone composition of the present invention can be in the form of grease and can be easily applied to small electronic components and heat sinks. Furthermore, the heat conductive silicone composition of the present invention can be cured by being interposed between the heat generating member and the cooling member. Moreover, after apply | coating to either a heat-emitting member or a cooling member once and making it harden | cure, it can combine with the other member by making it soften with a heat | fever.

Hereinafter, the thermally conductive silicone composition of the present invention will be described in more detail.
(A) A component is a main component of this composition and is represented by the following average composition formula (1).
(R ¹ ₃ SiO _1/2 ) _a (R ¹ ₂ SiO _2/2 ) _b (R ¹ SiO _3/2 ) _c (SiO _4/2 ) _d (R ² O _1/2 ) _e
(1)
The organopolysiloxane has a kinematic viscosity at 25 ° C. of 500 to 1,000,000 mm ² / s. Preferably, it has 1,000-10,000 mm < ² > / s. If the kinematic viscosity is less than the lower limit, sufficient hardness at room temperature of the resulting crosslinked product may not be obtained. On the other hand, when the value exceeds the upper limit, handling workability decreases. In the present invention, the kinematic viscosity is a value measured at 25 ° C. using an Ubbelohde Ostwald viscometer.

In Formula (1), R ¹ is a phenyl group, an alkyl group or a cycloalkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a hydrogen atom. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group.

The thermally conductive silicone composition of the present invention is characterized in that the component (A) has specific amounts of phenyl groups and SiH groups. That is, in the above formula, the phenyl group content is 50 to 80%, preferably 50 to 70%, of the total number of R ¹ . When the phenyl group amount is less than the lower limit, sufficient hardness cannot be obtained at room temperature. Exceeding the upper limit is not preferable because the mechanical strength of the resulting cured product is lowered. Further, in the above formula, the ratio of the number of hydrogen atoms in the total number of R ¹ is 10 to 20%, preferably 10 to 15%. When the amount of SiH groups is less than the lower limit, the obtained cured product cannot obtain sufficient hardness at room temperature. Moreover, when the said upper limit is exceeded, the hardened | cured material obtained will become inadequate softening at high temperature. The component (A) may have an alkenyl group, but the content of the alkenyl group is 0 to 20%, preferably 0 to 15%, of the total number of R ¹ . When the content of the alkenyl group exceeds the above upper limit, the resulting crosslinked product is not sufficiently softened at high temperature, which is not preferable.

In Formula (1), R ² is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Preferably, they are a methyl group and an ethyl group.

In the formula (1), a is a number indicating the ratio of siloxane units represented by the general formula: R ¹ ₃ SiO _1/2 , and 0 ≦ a ≦ 0.2, preferably a + b + c + d = 1 It is a number that satisfies 0 ≦ a ≦ 0.1. When a exceeds the above upper limit, the resulting cured product cannot obtain sufficient hardness at room temperature. b is a number indicating the ratio of the siloxane unit represented by the general formula: R ¹ ₂ SiO _2/2 , and 0.2 ≦ b ≦ 0.7, preferably 0.4 ≦ for a + b + c + d = 1. It is a number that satisfies b ≦ 0.7. When b is less than the above lower limit, the resulting cured product is insufficiently softened at a high temperature. If the above upper limit is exceeded, the resulting cured product will not have sufficient hardness at room temperature. c is a number indicating the ratio of the siloxane unit represented by the general formula: R ¹ SiO _3/2 , and 0.2 ≦ c ≦ 0.6, preferably 0.2 ≦ c with respect to a + b + c + d = 1. It is a number satisfying ≦ 0.5. When c is less than the above lower limit, the obtained cured product cannot obtain sufficient hardness at room temperature. Moreover, when the said upper limit is exceeded, softening at high temperature of the hardened | cured material obtained will become inadequate. In the formula, d is a number indicating the ratio of the siloxane unit represented by the general formula: SiO _4/2 , and 0 ≦ d ≦ 0.2, preferably 0 ≦ d ≦ 0, with respect to a + b + c + d = 1. It is a number satisfying 1. When d exceeds the above upper limit, the resulting crosslinked product is not sufficiently softened at high temperature. In the formula, e is a number indicating the ratio of units represented by the general formula: R ² O _1/2 and is a number satisfying 0 ≦ e ≦ 0.1. This is because if e exceeds the above upper limit, sufficient hardness at room temperature of the resulting crosslinked product cannot be obtained. In the formula, the sum of a, b, c, and d is 1.

  The component (B) is a linear organopolysiloxane having at least two alkenyl groups having 2 to 6 carbon atoms in one molecule. 40 to 70% of the total number of organic groups bonded to the silicon atom of the siloxane is a phenyl group. The composition is cured by hydrosilylation of the alkenyl group in component (B) with the SiH group in component (A).

The component (B) is preferably represented by the following general formula (2).
R ³ ₃ SiO (R ³ SiO) _m SiR ³ ₃ (2)

In formula (2), R ³ is independently a phenyl group, an alkyl group or a cycloalkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group. The content of the phenyl group of the total number of ^{R 3} is from 40 to 70%, preferably 50 to 70%. When the ratio of the phenyl group in (B) component exceeds the said upper limit, the mechanical strength of the obtained hardened | cured material will fall. In Formula (2), at least two of R ³ are alkenyl groups. If the number of alkenyl groups is less than 1, the component (B) is not taken into the crosslinking reaction and a cured product cannot be formed, or the cured product may not have sufficient hardness at room temperature.

  In Formula (2), m is an integer of 1-100, Preferably it is an integer of 1-50, More preferably, it is 1-20. If m exceeds the above upper limit, the resulting cured product may not have sufficient hardness at room temperature.

  In this composition, the amount of component (B) is such that the ratio of the number of SiH groups in component (A) to the total number of alkenyl groups in component (A) and component (B) is 0.5-2. The amount is preferably 0.5 to 1.5. When the amount of component (B) is less than the above lower limit, the resulting cured product may be insufficiently softened at high temperatures. Moreover, when it exceeds the above upper limit, there is a possibility that sufficient hardness at room temperature of the obtained cured product cannot be obtained.

  Component (C) is a thermally conductive filler and imparts thermal conductivity to the composition. The thermally conductive filler is preferably made of at least one material selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and carbon allotropes. For example, aluminum, silver, copper, metal silicon, alumina, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, silicon carbide, diamond, graphite, carbon nanotube, graphene, and the like can be given. The shape of the thermally conductive filler may be any of spherical shape, indefinite shape, and needle shape, and is not particularly limited.

  The thermally conductive filler is preferably a combination of a large particle size component and a small particle size component. The large particle size component means an average particle size of 10 to 120 μm, preferably 15 to 75 μm, and the average particle size of the large particle size component is less than the above lower limit, the resulting composition may have a too high viscosity. Above the above upper limit, the resulting composition may be non-uniform. The small particle size component is a filler having an average particle size of 0.01 to 10 μm, preferably 0.1 to 4 μm. There exists a possibility that the viscosity of the composition obtained may become too high that the average particle diameter of a small particle size component is less than the said minimum. Above the above upper limit, the resulting composition may be non-uniform. In addition, the average particle diameter in this invention can be calculated | required as a mass average value (or median diameter) in the particle size distribution measurement by a laser beam diffraction method.

  (C) The compounding quantity of a component is 100-3500 mass parts with respect to 100 mass parts of (A) component, Preferably it is 500-3000 mass parts. When the amount of component (C) is less than the above lower limit, the thermal conductivity is poor. Above the upper limit, the extensibility is poor.

Component (D) is a hydrosilylation catalyst and promotes a hydrosilylation reaction between the SiH group in component (A) and the alkenyl group in components (A) and (B). The hydrosilylation catalyst may be a conventionally known catalyst, and examples thereof include platinum-based, palladium-based, and rhodium-based catalysts. Of these, platinum or platinum compounds that are relatively easily available are preferred. More specifically, for example, platinum alone, platinum black, chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, platinum coordination compound and the like can be mentioned. A platinum-type catalyst may be used individually by 1 type or in combination of 2 or more types.

  The content of the component (D) is not particularly limited as long as it is a catalytic amount. The catalytic amount is an amount sufficient to promote the hydrosilylation reaction. Preferably, an amount that is 0.1 to 500 ppm, more preferably 1.0 to 100 ppm in terms of mass unit in terms of the amount of metal atoms of the catalyst with respect to the total mass of the composition. If the amount of component (D) is less than the above lower limit, the effect as a catalyst may not be obtained. On the other hand, if the value exceeds the upper limit, the catalytic effect does not increase and is uneconomical.

The thermally conductive silicone composition of the present invention further comprises (E) at least one silyl group represented by the following general formula (3) in one molecule, and a viscosity at 25 ° C. of 0.01 to 30 Pa · s. It can contain the organopolysiloxane which has. The component (E) functions as a wetter. (E) A component may be used individually by 1 type, or may use 2 or more types together.
-SiR ⁴ _f (OR ⁵ ) _3-f (3)
(In the formula (3), R ⁴ are each independently an unsubstituted or substituted monovalent hydrocarbon group, R ⁵ are each independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, and f Is 0, 1 or 2.

  The component (E) has a viscosity at 25 ° C. of 0.01 to 30 Pa · s, preferably 0.01 to 10 Pa · s. If the viscosity is less than the above lower limit, oil bleed is likely to occur from the silicone composition, and it tends to sag, which is not preferable. On the other hand, if it exceeds the above upper limit, the fluidity of the resulting silicone composition becomes extremely poor, and the coating workability may be deteriorated. In the present invention, the viscosity is a value measured by a rotational viscometer.

Examples of the component (E) include organopolysiloxanes represented by the following general formula.
(Wherein R ⁴ are each independently an unsubstituted or substituted monovalent hydrocarbon group, R ⁵ is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, and n is an integer of 2 to 100) And f is 0, 1 or 2.)

In the above formula, R ^{4 s} are each independently an unsubstituted or substituted monovalent hydrocarbon group having preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and further preferably 1 to 3 carbon atoms. Examples thereof include a linear alkyl group, a branched alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group, an aralkyl group, and a halogenated alkyl group. Examples of the linear alkyl group include a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, and a decyl group. Examples of the branched alkyl group include isopropyl group, isobutyl group, tert-butyl group, 2-ethylhexyl group and the like. Examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkenyl group include a vinyl group and an allyl group. Examples of the aryl group include a phenyl group and a tolyl group. Examples of the aralkyl group include a 2-phenylethyl group and a 2-methyl-2-phenylethyl group. Examples of the halogenated alkyl group include a 3,3,3-trifluoropropyl group, a 2- (nonafluorobutyl) ethyl group, and a 2- (heptadecafluorooctyl) ethyl group. Among these, as R ⁴ , a methyl group and a phenyl group are preferable.

In the above formula, R ^{5 s} independently of one another are an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. The number of carbon atoms is preferably 1-8. Examples of the alkyl group include linear alkyl groups, branched-chain alkyl groups, and include cyclic alkyl groups, in particular include the groups exemplified in R ^4. Examples of the alkoxyalkyl group include a methoxyethyl group and a methoxypropyl group. Examples of the alkenyl group include the groups exemplified for R ⁴ . Examples of the acyl group include an acetyl group and an octanoyl group. Among these, R ⁵ is preferably an alkyl group, particularly preferably a methyl group or an ethyl group. n is 2-100, Preferably it is 5-50. f is 0, 1 or 2, preferably 0.

(E) As organopolysiloxane, the following are mentioned, for example.
(In the above formulas, Me is a methyl group)

  It is preferable that content of (E) component is 0.1-80 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 10-80 mass parts. If it exceeds the above upper limit, the cured product may not have sufficient hardness at room temperature.

The silicone composition of the present invention may further contain (F) an organopolysiloxane in which the phenyl group in the silicon atom-bonded organic group is less than 40 mol%. The organopolysiloxane has at least two alkenyl groups bonded to silicon atoms in one molecule and has a kinematic viscosity at 25 ° C. of 10 to 10,000 mm ² / s. The component (F) forms a crosslinked structure by hydrosilylation with a silicon atom-bonded hydrogen atom in the silicone composition.

  (F) A component may be used individually by 1 type, or may use 2 or more types together. Component (F) may be linear or branched, and two or more organopolysiloxanes having different viscosities may be used in combination. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-butenyl group, and a 1-hexenyl group, and a vinyl group is preferable from the viewpoint of ease of synthesis and cost. The alkenyl group bonded to the silicon atom may be present at any end of the molecular chain of the organopolysiloxane, but is preferably present at least at the end.

Examples of the organic group other than the alkenyl group bonded to the silicon atom include a substituted or unsubstituted monovalent hydrocarbon group. Examples of the monovalent hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group, and dodecyl group, aryl groups such as phenyl group, 2-phenylethyl group, and 2-phenylpropyl group. And an aralkyl group such as a group. Moreover, the monovalent hydrocarbon group (for example, chloromethyl group, 3,3,3-trifluoropropyl group etc.) by which the hydrogen atom couple | bonded with the carbon atom of the said hydrocarbon group was substituted with the halogen atom is mentioned. Among these, a methyl group and a phenyl group are preferable from the viewpoint of ease of synthesis and cost. The component (F) preferably has a kinematic viscosity of 10 to 100,000 mm ² / s at 25 ° C., more preferably 100 to 50,000 mm ² / s. If this is less than the above lower limit, the storage stability of the silicone composition may deteriorate. On the other hand, if it exceeds the upper limit, the extensibility of the resulting silicone composition may be deteriorated.

(F) It is preferable that content of a component is 0.1-50 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 10-50 mass parts. When the amount of the component (F) exceeds the above upper limit, the cured product may be insufficiently softened at a high temperature.

  The silicone composition of the present invention may further contain (G) a linear organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms in one molecule. The organohydrogenpolysiloxane is crosslinked by hydrosilylation reaction of alkenyl groups in the composition to form a network structure.

  (G) A component may be used individually by 1 type, or may use 2 or more types together. Examples of the organic group bonded to the silicon atom of the linear organohydrogenpolysiloxane include a substituted or unsubstituted monovalent hydrocarbon group. Examples of the monovalent hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a dodecyl group, an aryl group such as a phenyl group, a 2-phenylethyl group, and a 2-phenylpropylene group. And a monovalent hydrocarbon group in which a hydrogen atom bonded to a carbon atom of the hydrocarbon group is substituted with a halogen atom or a glycidoxy group (for example, a chloromethyl group, 3,3,3-trialkyl group). Fluoropropyl group, 2-glycidoxyethyl group, 3-glycidoxypropyl group, 4-glycidoxybutyl group, etc.).

  The amount of component (G) is such that the ratio of the total number of SiH groups to the total number of alkenyl groups in the silicone composition is 0.5-2, preferably 0.5-1.5. It is. This is because the cured product obtained when the content of the component (G) is less than the lower limit of the above range may not have sufficient hardness at room temperature. On the other hand, when the above upper limit is exceeded, the cured product is not preferable because softening at high temperatures may be insufficient.

  This invention is a silicone composition containing the said (A)-(D) component and arbitrary (E)-(G) component. In addition to the components (A) to (G), (H) a reaction control agent and (I) an adhesion promoter may be contained as optional components.

  (H) The reaction control agent suppresses the progress of the hydrosilylation reaction at room temperature and prolongs shelf life and pot life. Known reaction control agents can be used, such as ethynylhexanol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl- Alkyne alcohols such as 3-butyn-2-ol; Enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; 1,3,5,7- Examples include tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, and benzotriazole. These reaction control agents may be used alone or in combination of two or more. The amount of the reaction control agent is not limited as long as the effects of the present invention are not impaired, but for example, it is preferably 1 to 5000 ppm with respect to the total mass of the silicone composition.

  (I) The adhesion promoter further improves the adhesion to the substrate in contact with the curing process. Examples of the adhesion promoter include trialkoxysiloxane group (for example, trimethoxysiloxy group, triethoxysiloxy group) or trialkoxysilylalkyl group (for example, trimethoxysilylethyl group, triethoxysilylethyl group) and hydrosilyl group. Or an organosilane having an alkenyl group (for example, vinyl group, allyl group), or a linear, branched or cyclic organosiloxane oligomer having about 4 to 20 silicon atoms; trialkoxysiloxane group or trialkoxysilyl Organosilane having an alkyl group and a methacryloxyalkyl group (for example, 3-methacryloxypropyl group), or an organosiloxane oligomer having a linear structure, a branched structure or a cyclic structure having about 4 to 20 silicon atoms; A xysiloxy group or trialkoxysilylalkyl group and an epoxy group-bonded alkyl group (for example, 3-glycidoxypropyl group, 4-glycidoxybutyl group, 2- (3,4-epoxycyclohexyl) ethyl group, 3- (3,4-epoxycyclohexyl) propyl group) or an organosiloxane oligomer having a linear structure, a branched structure or a cyclic structure having about 4 to 20 silicon atoms; aminoalkyltrialkoxysilane and epoxy Examples include a reaction product of a group-bonded alkyltrialkoxysilane and an epoxy group-containing ethyl polysilicate. More specifically, vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropyl Trimethoxysilane, 3-methacryloxypropyltriethoxysilane, reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, silanol-blocked methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxy Silane condensation reaction product, silanol-blocked methyl vinyl siloxane oligomer and 3-glycidoxypropyltrimethoxysilane condensation reaction product, silanol-blocked methyl vinyl siloxane oligomer and 3-meta Lilo propyl condensation reaction product triethoxysilane, and tris (3-trimethoxysilylpropyl) isocyanurate.

  Furthermore, the silicone composition of the present invention includes, as other optional components, polyorganosiloxanes other than the above components (A) to (I); silica, glass, alumina, zinc oxide, etc., unless the object of the present invention is impaired. An inorganic filler; organic resin fine powder such as polymethacrylate resin; a heat-resistant agent, a dye, a pigment, a phosphor, a flame retardant, and a solvent.

  The silicone composition of the present invention is preferably in the form of a grease. Being grease-like, it can be easily applied to small electronic components or heat sinks. The viscosity of the silicone composition at 25 ° C. is not particularly limited, but is preferably in the range of 10 to 500 Pa · s, and more preferably in the range of 10 to 300 Pa · s. When the viscosity is less than the above lower limit, the handleability of the composition is deteriorated. Moreover, when it exceeds the said upper limit, when a composition is dispense-applied etc., it becomes easy to chew foam, and it is not preferable. In the present invention, the viscosity of the silicone composition can be measured, for example, with a spiral viscometer.

  The silicone composition preferably has a thermal conductivity of at least 1.0 W / mK, and particularly preferably 2.0 W / mK or more. If the thermal conductivity is less than the above lower limit, the desired heat dissipation performance cannot be obtained, which is not preferable.

  The manufacturing method of this silicone composition should just follow the manufacturing method of the conventional silicone composition, and is not restrict | limited in particular. For example, the above-mentioned components (A) to (I) and other necessary components are mixed with Trimix, Twinmix, Planetary Mixer (all registered trademark of mixer manufactured by Inoue Seisakusho Co., Ltd.), Ultramixer (Mizuho Industry Co., Ltd.) It can be manufactured by a method of mixing with a mixer such as a registered trademark of a mixer manufactured by Hibisu Dispersix (registered trademark of a mixer manufactured by Tokushu Kika Kogyo Co., Ltd.).

  A cured product can be obtained by crosslinking the silicone composition by a hydrosilylation reaction. The curing conditions of the composition are not particularly limited, and may be according to the curing conditions of a conventional addition reaction curable silicone composition. The cured product is solid at room temperature, for example, 25 ° C., more specifically, soft rubber, and is characterized by being softened or liquefied at a high temperature, for example, 100 ° C. The cured product preferably has an Asker C hardness of 5 or more at 25 ° C. Moreover, it is preferable that this hardened | cured material is a soft rubber-like thing which has fluidity | liquidity at 100 degreeC, or whose modulus is 2.0 MPa or less at 100 degreeC. The fluidity at 100 ° C. is not particularly limited, but is preferably at least 100 Pa · s or more, preferably 100 Pa · s to 300 Pa · s, more preferably 100 to 200 Pa · s. Is good. The cured product having such characteristics can be suitably used as a heat conductive heat radiating member that is softened by heating. The modulus in the present invention means a value of storage elastic modulus (E ′) measured by dynamic viscoelasticity measurement (DMA) described in JIS K7244-4.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example.

Each component used in the examples and comparative examples is as follows. In the formula, Me, Ph, and Vi represent a methyl group, a phenyl group, and a vinyl group, respectively. In the following, the amount of Ph groups is the number ratio of phenyl groups to the total number of hydrogen atoms and substituents bonded to silicon atoms. Further, the amount of SiH groups is the number ratio of SiH groups to the total number of hydrogen atoms and substituents bonded to silicon atoms. The kinematic viscosity is a value measured at 25 ° C. using an Ubbelohde Ostwald viscometer.
Component (A): Organohydrogenpolysiloxane represented by the following average unit formula A-1: Average unit formula (Me ₃ SiO _1/2 ) _0.10 (MeHSiO _2/2 ) _0.25 (Ph ₂ SiO _{2 / 2} ) _0.30 (PhMeSiO _2/2 ) _0.10 (PhSiO _3/2 ) _0.25 (MeO _1/2 ) _0.05 , kinematic viscosity: 2,840 mm ² / s, Ph group amount: 51% , SiH group content: 13.5%
A-2: Average unit formula (Me ₃ SiO _1/2 ) _0.10 (MeViSiO _2/2 ) _0.05 (MeHSiO _2/2 ) _0.20 (Ph ₂ SiO _2/2 ) _0.30 (PhMeSiO _{2 / 2} ) _0.10 (PhSiO _3/2 ) _0.25 (MeO _1/2 ) _0.05 , kinematic viscosity: 2,132 mm ² / s, Ph group amount: 51%, SiH group amount: 10.8%
A-3: Average unit formula (Me ₃ SiO _1/2 ) _0.15 (MeHSiO _2/2 ) _0.25 (Ph ₂ SiO _2/2 ) _0.30 (PhMeSiO _2/2 ) _0.15 (PhSiO _{3 / 2} ) _0.15 (MeO _1/2 ) _0.05, kinematic viscosity: 1,120 mm ² / s, Ph group amount: 45%, SiH group amount: 12.5%
A-4: Average unit formula (Me ₃ SiO _1/2 ) _0.10 (MeHSiO _2/2 ) _0.10 (Ph ₂ SiO _2/2 ) _0.35 (PhMeSiO _2/2 ) _0.2 (PhSiO _{3 / 2} ) _0.25 (MeO _1/2 ) _0.05 , kinematic viscosity: 2,340 mm ² / s, Ph group amount: 62%, SiH group amount: 5.4%

(B) Component: Organopolysiloxane represented by the following formula B-1: Organotrisiloxane represented by the following formula
Ph group content: 67%

(C) Component C-1: Spherical aluminum oxide with an average particle size of 1.0 μm C-2: Spherical aluminum oxide with an average particle size of 10 μm C-3: Spherical aluminum oxide with an average particle size of 45 μm C-4: Average particle size of 70 μm Spherical aluminum oxide (D) component D-1: F-1 solution of platinum-divinyltetramethyldisiloxane complex (containing 1% by mass as platinum atom) (F-1 is an organopolysiloxane of the following component (F) is there)

(E) Component E-1: Organopolysiloxane represented by the following formula (viscosity at 25 ° C .: 0.03 Pa · s)

(F) Component F-1: Organopolysiloxane represented by the following formula (kinematic viscosity at 25 ° C. 700 mm ² / s)
(Ph base amount: 30%)

(G) Component G-1: Organohydrogenpolysiloxane represented by the following formula
G-2: Organohydrogenpolysiloxane represented by the following formula

(H) Component H-1: 1-Ethynyl-1-cyclohexanol (I) Component I-1: Organohydrogenpolysiloxane represented by the following formula

[Examples 1-7, Comparative Examples 1-4]
The above components were mixed in the amounts shown in Table 1 or 2 according to the following method to obtain a silicone composition. That is, the components (A), (B), (C), (E), and (F) are added to a 5-liter gate mixer (Inoue Seisakusho Co., Ltd., trade name: 5-liter planetary mixer). The mixture was degassed and heated at 150 ° C. for 1 hour. Then, it cools until it becomes normal temperature (25 degreeC), (H) component is added, it mixes at room temperature (25 degreeC) so that it may become uniform, (D) component is added continuously, and it is room temperature so that it may become uniform (25 ° C). Further, components (G) and (I) were added and deaerated and mixed at room temperature so as to be uniform.
Each of the silicone compositions obtained above was cured according to the following method to form a thermally conductive molded product. The viscosity of each silicone composition, the hardness after curing of the cured product, the thermal conductivity, and the modulus were evaluated by the methods shown below. The results are listed in Tables 1 and 2.

[Measurement of viscosity at 25 ° C. of silicone composition]
The initial viscosity at 25 ° C. of the silicone composition was measured. The viscosity was measured using a spiral viscometer: Malcolm viscometer (type PC-10AA, rotation speed 10 rpm).
[Thermal conductivity]
The thermal conductivity of the silicone composition before curing at 25 ° C. was measured using a hot disk method thermophysical property measuring apparatus TPS 2500 S manufactured by Kyoto Electronics Industry Co., Ltd. (a hot disk method based on ISO 22007-2).
[Evaluation of hardness after curing]
The silicone composition was poured into a mold having a cured thickness of 6 mm and cured at 125 ° C. for 1 hour. Next, two 6 mm thick cured products were stacked and the hardness was measured with an Asker C hardness tester.
[Measurement of viscosity of cured product at 100 ° C]
Moreover, after heating this hardened | cured material to 100 degreeC, the viscosity was measured according to the method mentioned above.
In addition, since the hardened | cured material obtained from the silicone composition of Examples 1-5 had a soft rubber form at 100 degreeC, the viscosity was not able to be measured.
[Modulus evaluation after curing]
The silicone composition was poured into a mold having a cured thickness of 2 mm and cured at 125 ° C. for 1 hour. Next, the cured product having a thickness of 2 mm was punched out so as to have a strip shape of 1.0 cm × 3.0 cm. For the cured product that has been punched, the modulus from 25 ° C. to 100 ° C. is measured using a viscoelasticity measuring device DMA 7100 manufactured by Hitachi High-Tech Science Co., Ltd. Changes were measured. Tables 1 and 2 show the modulus (MPa) at 25 ° C and the modulus (MPa) at 100 ° C.
In addition, since the hardened | cured material obtained from the composition of Example 6 and 7 had fluidity | liquidity (liquefied) at 100 degreeC, a modulus was not able to be measured.

  As shown in Table 2 above, the cured product obtained by curing the compositions of Comparative Examples 1 and 2 containing the organopolysiloxane (A-3) having a small amount of phenyl groups is sufficient at room temperature (25 ° C.). Hardness cannot be obtained. In addition, a cured product obtained by curing the compositions of Comparative Examples 3 and 4 containing the organopolysiloxane (A-4) whose SiH amount is less than the lower limit can also obtain a sufficient hardness at room temperature (25 ° C.). Absent. Furthermore, the obtained cured product has a high viscosity at 100 ° C. and does not have fluidity. On the other hand, as shown in Table 1 above, the cured product composed of the silicone compositions of Examples 1 to 7 is a solid (soft rubber) having an Asker C hardness of 5 or more at room temperature (25 ° C.). Moreover, the hardened | cured material of Examples 1-5 softened at high temperature (100 degreeC) so that the value of the modulus in 25 degreeC and the value of the modulus in 100 degreeC were understood. Moreover, the hardened | cured material of Example 6 and 7 was liquefied at high temperature (100 degreeC).

  The thermally conductive silicone composition of the present invention can provide a cured product having thermoplasticity by heat curing. Moreover, since the heat conductive silicone composition of this invention has a grease form, it can also be hardened by interposing this composition between a heat generating member and a cooling member. Furthermore, it can be combined with the other member by once applying and curing to either one of the heat generating member or the cooling member and then softening with heat. Therefore, the thermally conductive silicone composition of the present invention can be easily applied to electronic components and heat sinks, and can be suitably used even in small electronic components.

Claims (8)

A kneading viscosity at 25 ° C. of 500 to 1,000,000 mm ² / s represented by the average composition formula (1) including the following components (A) to (D): Organopolysiloxane having: 100 parts by mass,
(R ¹ ₃ SiO _1/2 ) _a (R ¹ ₂ SiO _2/2 ) _b (R ¹ SiO _3/2 ) _c (SiO _4/2 ) _d (R ² O _1/2 ) _e
(1)
(In the formula, R ¹ is independently of each other a phenyl group, an alkyl group or a cycloalkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a hydrogen atom, provided that the total number of R ¹ is 50-80% of them are phenyl groups, 10-20% of the total number of R ¹ are hydrogen atoms, 0-20% of the total number of R ¹ are alkenyl groups, and R ² is hydrogen. It is an atom or an alkyl group having 1 to 6 carbon atoms, and a, b, c, d and e are 0 ≦ a ≦ 0.2, 0.2 ≦ b ≦ 0.7, 0.2 ≦ c ≦ 0. (6, 0 ≦ d ≦ 0.2, 0 ≦ e ≦ 0.1, and a + b + c + d = 1)
(B) A linear organopolysiloxane having at least two alkenyl groups having 2 to 6 carbon atoms in one molecule, and 40 to 70% of the total number of organic groups bonded to silicon atoms is a phenyl group The amount of the ratio of the number of SiH groups in the component (A) to the total number of alkenyl groups in the organopolysiloxane (A) component and the component (B) is 0.5 to 2,
(C) Thermally conductive filler: 100-3500 parts by mass, and (D) hydrosilylation catalyst. The thermally conductive silicone composition R ³ ₃ SiO (R ³ SiO) _m SiR ³ ₃ (2) according to claim 1, wherein the component (B) is represented by the following general formula (2).
(In the formula, R ³ is independently of each other a phenyl group, an alkyl group or a cycloalkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, provided that the total number of R ³ is 40 to 70% of them are phenyl groups, at least two of R ³ are alkenyl groups, and m is an integer of 1 to 100). Furthermore, (E) an organopolysiloxane having at least one silyl group represented by the following general formula (3) in one molecule and having a viscosity of 0.01 to 30 Pa · s at 25 ° C. (A) component 100 The heat conductive silicone composition of Claim 1 or 2 contained by 0.1-80 mass parts with respect to a mass part.
-SiR ⁴ _f (OR ⁵ ) _3-f (3)
(Wherein R ⁴ are each independently an unsubstituted or substituted monovalent hydrocarbon group, R ⁵ are each independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group, and f is 0, 1 or 2). And (F) an organopolysiloxane having at least two alkenyl groups in one molecule and a kinematic viscosity at 25 ° C. of 10 to 100,000 mm ² / s, the total number of organic groups bonded to silicon atoms The organopolysiloxane in which the ratio of the number of phenyl groups bonded to silicon atoms relative to is less than 40% is 0.1 to 50 parts by mass with respect to 100 parts by mass of the component (A). The heat conductive silicone composition of any one of these.   Further, (G) the ratio of the total number of SiH groups to the total number of alkenyl groups in the composition of the linear organohydrogenpolysiloxane having at least two SiH groups in one molecule is 0.5 to 2. The heat conductive silicone composition of any one of Claims 1-4 contained in quantity.   Viscosity at 25 ° C. 10 to 500 Pa. The thermally conductive silicone composition according to any one of claims 1 to 5, which has s and is in the form of a grease. Hardened | cured material formed by hardening | curing the heat conductive silicone composition of any one of Claims 1-6.   The cured product according to claim 7, having an Asker C hardness of 5 or more at 25 ° C. and fluidity at 100 ° C. or a modulus of 2.0 MPa or less at 100 ° C.