JP7717432B2 - Thermally conductive silicone composition - Google Patents

Description

The present invention relates to a thermally conductive silicone composition.

In recent years, the increasing performance and miniaturization of electronic components such as power modules and CPUs has created a demand for thermal management. Thermally conductive grease and heat dissipation sheets are used for this thermal management. However, thermally conductive grease has issues with pumping out, where the thermal expansion and contraction of the heating elements and heat exchanger causes the grease to be pushed out from the application area, as well as issues with the filler and oil separating over time, and the reliability and functionality of thermally conductive grease are still in the development stage. On the other hand, thermally conductive sheets are molded products and do not suffer from the above-mentioned issues, but there are concerns about their heat dissipation performance due to the thermal resistance and contact resistance that arise as the thickness of the heat dissipation sheet itself increases.

To address this issue, a technique has been proposed in which large particle size inorganic fillers or multiple types of inorganic fillers are used to increase the thermal conductivity of compositions containing thermally conductive fillers and silicone. For example, Patent Document 1 discloses a thermally conductive polysiloxane composition that uses silicon carbide with at least two peaks in its particle size distribution.

JP 2017-88685 A

When considering thermal resistance, applying a thin layer of heat dissipation material is an important factor. BLT (Bond-Line-Thickness) is an indicator of how thinly the material can be applied. The thickness of a heat dissipation material has a significant impact on its heat dissipation performance, and making it thinner contributes to reducing thermal resistance, so BLT characteristics are important for high heat dissipation materials.

Furthermore, according to the inventors' findings, it was found that there is room for improvement in the electrical insulation properties, BLT properties, dischargeability, and heat dissipation properties of the thermally conductive polysiloxane composition described in Patent Document 1.

The object of the present invention is to provide a thermally conductive silicone composition that has excellent electrical insulation properties, ejection properties, and heat dissipation properties, as well as a low BLT.

The present invention relates to the following [1] to [6].
[1] (A) a polyorganosiloxane having an alkenyl group bonded to a silicon atom;
(B) a polyorganohydrogensiloxane having a hydrogen atom bonded to a silicon atom;
(C) platinum-based catalyst;
(D) the following general formula (1):

[During the ceremony,
R ¹ : a group having an alkoxysilyl group having 1 to 4 carbon atoms; R ² : a group represented by the following general formula (2):

(wherein R4 ^'s are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms; Y is a group selected from the group consisting of R4 ^'s and aliphatic unsaturated groups; and d is an integer from 2 to 60); X's are each independently a divalent hydrocarbon group having 2 to 10 carbon atoms; a and b are each independently an integer of 1 or greater; c is an integer of 0 or greater; a+b+c is an integer of 4 or greater; and ^R3 's are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom.
and (E) a thermally conductive filler,
A thermally conductive silicone composition comprising:
The component (A) includes (A-1) a polyorganosiloxane having two or more silicon-bonded alkenyl groups in the molecule,
The component (B) includes (B-1) a polyorganohydrogensiloxane having two or more silicon-bonded hydrogen atoms in the molecule,
The component (E) is
(E-1) Silicon carbide having a particle size distribution peak in the range of 10 μm or more and 40 μm or less;
(E-2) a first thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of 0.1 μm to 1.0 μm;
(E-3) a second thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of more than 1.0 μm and less than 10 μm, and (E-4) a third thermally conductive filler (excluding silicon carbide) having a thermal conductivity of 60 W/mK to 300 W/mK and a particle size distribution peak in the range of 10 μm or more and 40 μm or less,
the total content of components (A), (B), and (C) is 1.0 to 10.0 parts by mass per 100 parts by mass of component (E); and
A thermally conductive silicone composition, in which the amount of component (E-2) is 28.0 parts by mass or less per 100 parts by mass of component (E).
[2] The component (E-2) is at least one selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, crystalline silica, aluminum, boron nitride, and graphitized carbon;
The component (E-3) is at least one selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, crystalline silica, aluminum, boron nitride, and graphitized carbon; and
The thermally conductive silicone composition according to [1], wherein component (E-4) is at least one member selected from the group consisting of aluminum nitride, boron nitride, and graphitized carbon.
[3] The thermally conductive silicone composition according to [1] or [2], further comprising at least one member selected from the group consisting of (A-2) a polyorganosiloxane having one silicon-bonded alkenyl group per molecule, and (B-2) a polyorganohydrogensiloxane having one silicon-bonded hydrogen atom per molecule.
[4] For 100 parts by mass of the component (E),
The content of the component (E-1) is 5.0 to 30.0 parts by mass,
The content of the component (E-2) is 10.0 to 28.0 parts by mass,
The content of the component (E-3) is 15.0 to 40.0 parts by mass, and the content of the component (E-4) is 5.0 to 40.0 parts by mass.
The thermally conductive silicone composition according to any one of [1] to [3].
[5] A cured product obtained by curing the thermally conductive silicone composition according to any one of [1] to [4].
[6] An electronic component comprising the thermally conductive silicone composition according to any one of [1] to [4].

The present invention provides a thermally conductive silicone composition that has excellent electrical insulation, ejection properties, and heat dissipation properties, as well as a low BLT.

[Definition of terms]
The structural units of siloxane compounds may be represented by the following abbreviations (hereinafter, these structural units may be referred to as "M units", " ^DH units", etc.).
M :Si( _CH3 ) _{3O1 /2}
M ^H :SiH( _CH3 ) _{2O1 /2}
M ^Vi :(CH=CH ₂ )(CH ₃ ) ₂ SiO _1/2
D :Si( _CH3 ) _{2O2 /2}
D ^H :SiH( _CH3 )O2 _/2

In this specification, specific examples of groups are as follows.
Examples of the monovalent hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group. Examples of the monovalent hydrocarbon group having no aliphatic unsaturated bond include the above-mentioned monovalent hydrocarbon groups other than an alkenyl group.
The alkenyl group is a straight-chain or branched group having 2 to 6 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 3-butenyl group, and a 5-hexenyl group.
The alkyl group is a straight-chain or branched group having 1 to 18 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, and an octadecyl group.
The cycloalkyl group is a monocyclic or polycyclic group having 3 to 20 carbon atoms, and examples thereof include a cyclopentyl group and a cyclohexyl group.
The aryl group is an aromatic group containing a monocyclic or polycyclic group having 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.
The aralkyl group is an alkyl group substituted with an aryl group, and examples thereof include a 2-phenylethyl group and a 2-phenylpropyl group.
The alkylene group is a straight-chain or branched group having 1 to 18 carbon atoms, and examples thereof include a methylene group, an ethylene group, a trimethylene group, a 2-methylethylene group, and a tetramethylene group.
The alkenyl group, alkyl group, cycloalkyl group, aryl group, aralkyl group and alkylene group may be substituted with a halogen such as chlorine, fluorine or bromine, a cyano group, etc. Examples of the group substituted with a halogen include a chloromethyl group, a chlorophenyl group and a 3,3,3-trifluoropropyl group, and examples of the group substituted with a cyano group include a 2-cyanoethyl group.

In this specification, "(A) polyorganosiloxane having an alkenyl group bonded to a silicon atom" is also referred to as "component (A)." The same applies to "(C) platinum-based catalyst," etc.

[Thermal conductive silicone composition]
The thermally conductive silicone composition (hereinafter also simply referred to as "composition") comprises the following:
(A) a polyorganosiloxane having an alkenyl group bonded to a silicon atom;
(B) a polyorganohydrogensiloxane having a hydrogen atom bonded to a silicon atom;
(C) platinum-based catalyst;
(D) the following general formula (1):

[During the ceremony,
R ¹ : a group having an alkoxysilyl group having 1 to 4 carbon atoms; R ² : a group represented by the following general formula (2):

(wherein R4 ^'s are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms; Y is a group selected from the group consisting of R4 ^'s and aliphatic unsaturated groups; and d is an integer from 2 to 60); X's are each independently a divalent hydrocarbon group having 2 to 10 carbon atoms; a and b are each independently an integer of 1 or greater; c is an integer of 0 or greater; a+b+c is an integer of 4 or greater; and ^R3 's are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom.
and (E) a thermally conductive filler,
A thermally conductive silicone composition comprising:
The component (A) includes (A-1) a polyorganosiloxane having two or more silicon-bonded alkenyl groups in the molecule,
The component (B) includes (B-1) a polyorganohydrogensiloxane having two or more silicon-bonded hydrogen atoms in the molecule,
The component (E) is
(E-1) Silicon carbide having a particle size distribution peak in the range of 10 μm or more and 40 μm or less;
(E-2) a first thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of 0.1 μm to 1.0 μm;
(E-3) a second thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of more than 1.0 μm and less than 10 μm, and (E-4) a third thermally conductive filler (excluding silicon carbide) having a thermal conductivity of 60 W/mK to 300 W/mK and a particle size distribution peak in the range of 10 μm or more and 40 μm or less,
the total content of components (A), (B), and (C) is 1.0 to 10.0 parts by mass per 100 parts by mass of component (E); and
The content of the component (E-2) is 28.0 parts by mass or less per 100 parts by mass of the component (E).

<(A) Polyorganosiloxane having an alkenyl group bonded to a silicon atom>
(A) Polyorganosiloxane having silicon-bonded alkenyl groups is a component that serves as the base polymer in the composition. Component (A) includes (A-1) polyorganosiloxane having two or more silicon-bonded alkenyl groups per molecule.

<<(A-1) Polyorganosiloxane Having Two or More Silicon-Bonded Alkenyl Groups in the Molecule>>
Component (A-1) is a polyorganosiloxane having two or more silicon-bonded alkenyl groups per molecule. An addition reaction between the alkenyl groups of component (A-1) and the hydrosilyl groups (Si—H groups) of component (B-1) forms a network structure in the cured product of the composition.

The component (A-1) is not particularly limited as long as it can form the network structure together with the component (B-1). The component (A-1) is typically represented by the general formula (I):
(R ¹¹ ) _a1 (R ¹² ) _b1 SiO _(4-a1-b1)/2 (I)
(In the formula,
R ¹¹ is an alkenyl group;
R ¹² is a monovalent hydrocarbon group having no aliphatic unsaturated bonds;
a1 is an integer from 1 to 3;
b1 is an integer of 0 to 2, provided that a1+b1 is 1 to 3.
The number of alkenyl groups bonded to silicon atoms in component (A-1) is preferably 2 to 100, and more preferably 2 to 50, per molecule.

R ¹¹ is preferably a vinyl group from the viewpoints of ease of synthesis and not impairing the fluidity of the composition before curing or the heat resistance of the composition after curing. a is preferably 1 from the viewpoint of ease of synthesis. R ¹² is preferably a methyl group or a phenyl group, and particularly preferably a methyl group, from the viewpoints of ease of synthesis and an excellent balance of properties such as mechanical strength and fluidity before curing.

The organic group bonded to the silicon atom of the other siloxane units in component (A-1) may be a monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond. For the same reasons as for ^R12 , this organic group is preferably a methyl group or a phenyl group, with a methyl group being particularly preferred.

R ¹¹ may be located at either the terminal or intermediate position of the molecular chain of component (A-1), or may be located at both positions.

The siloxane skeleton of component (A-1) can be linear or branched. That is, component (A-1) can be either (A-1-1) a linear polyorganosiloxane or (A-1-2) a branched polyorganosiloxane.

Examples of the linear polyorganosiloxane (A-1-1) include linear polyorganosiloxanes in which both ends are blocked with R ₃ SiO _1/2 units and the intermediate units are solely R ² ₂ SiO _2/2 units (wherein R is R ¹¹ or R ¹² , R ¹¹ is an alkenyl group, R ¹² is a monovalent hydrocarbon group free of aliphatic unsaturated bonds, and the molecule contains two or more R ¹¹ ). The R ₃ SiO _1/2 units in component (A1-1) are preferably R ¹¹ R ¹² ₂ SiO _1/2 units, R ¹¹ ₂ R ¹² SiO 1/2 units, or R ¹¹ ₃ SiO _{1/2 units} , with R ¹¹ R ¹² ₂ SiO _1/2 units being particularly preferred.

It is more preferable that the component (A-1) is a linear polyorganosiloxane in which both ends are blocked with R ¹¹ R ¹² ₂ SiO _1/2 units and the intermediate units are composed only of R ¹² ₂ SiO _2/2 units. It is particularly preferable that the component (A1-1) is a linear polyorganosiloxane represented by M ^vi D _n M ^vi (i.e., a linear polyorganosiloxane in which both ends are blocked with M ^vi units (dimethylvinylsiloxane units) and the intermediate units are composed only of D units (dimethylsiloxane units)). In this specification, "D _n " means that the intermediate units are composed only of D units, and here, "n" means the degree of polymerization of the D units, and is a value that changes depending on the viscosity of the polyorganosiloxane in question.

(A-1-2) Examples of branched polyorganosiloxanes include branched polyorganosiloxanes containing SiO _4/2 units and R ₃ SiO _1/2 units as essential units, and R ₂ SiO _2/2 units and/or RSiO _3/2 units as optional units. Here, R is R ¹¹ or R ¹² , and in R, two or more R ^11s per molecule. In order to form crosslinking points in the curing reaction, it is preferable that at least three Rs per molecule are R ¹¹ , with the remainder being R ^12. From the viewpoint that the cured product of the composition has excellent mechanical strength, the molar ratio of R ₃ SiO _1/2 units to SiO _4/2 units is preferably in the range of 1:0.8 to 1:3, and is a solid or viscous semi-solid resin at room temperature.

In the component (A-1-2), R ¹¹ may be present as R in an R ₃ SiO _1/2 unit, or as R in an R ₂ SiO unit or an RSiO _3/2 unit. From the viewpoint of achieving rapid curing at room temperature, it is preferred that some or all of the R ₃ SiO _1/2 units be R ¹¹ R ¹² ₂ SiO _1/2 units.

<Component (A) other than component (A-1)>
Component (A) may contain an (A) component other than component (A-1) (hereinafter also referred to as component (A-2)). Component (A-2) may be a polyorganosiloxane having one alkenyl group bonded to a silicon atom in the molecule. The siloxane skeleton of component (A-2), including preferred embodiments, is as described above for component (A-1).

The component (A-2) is preferably a linear polyorganosiloxane having one alkenyl group bonded to a silicon atom in the molecule. The component (A-2) is more preferably a linear polyorganosiloxane in which one end is blocked with an R ¹¹ R ¹² ₂ SiO _1/2 unit, the other end is blocked with an R ¹² ₃ SiO _1/2 unit, and the intermediate unit is composed only of an R ¹² ₂ SiO _2/2 unit. Furthermore, the component (A-2) is particularly preferably a linear polyorganosiloxane represented by M ^vi D _n M.

<Preferred embodiments of component (A)>
The viscosity of component (A) at 23°C is preferably 0.01 to 500 Pa·s, more preferably 0.05 to 300 Pa·s, and particularly preferably 0.1 to 100 Pa·s. When the viscosity of component (A) is within this range, the filler and polymer can be easily kneaded together during the production process, resulting in a composition with excellent electrical insulation properties, BLT properties, dischargeability, and heat dissipation properties in the final product. Furthermore, when the viscosity of component (A) is 0.01 Pa·s or greater at 23°C, volatilization of low-molecular-weight components during the production process is suppressed, allowing the properties of the thermally conductive silicone composition to be efficiently satisfied. On the other hand, when the viscosity of component (A) is 500 Pa·s or less at 23°C, component (E) and the polymer components (component (A) and component (B)) tend to clump together. Here, when the component (A) is a combination of two or more types, the viscosity of the component (A) refers to the viscosity of the mixed alkenyl group-containing polyorganosiloxane. In this specification, the viscosity is a value measured in accordance with JIS K 6249 using a rotational viscometer with an appropriate spindle number and rotation speed at 23°C.

Component (A) may be a single component or a combination of two or more components. For example, component (A) may consist of only two or more (A-1) components, or may be a mixture of one or more (A-1) components and one or more (A-2) components.

<(B) Polyorganohydrogensiloxane having hydrogen atoms bonded to silicon atoms>
The polyorganohydrogensiloxane (B) having a silicon-bonded hydrogen atom includes (B-1) a polyorganohydrogensiloxane having two or more silicon-bonded hydrogen atoms per molecule. Component (B) is not particularly limited as long as it can form the network structure described above together with component (A).

<<(B-1) Polyorganohydrogensiloxane having two or more silicon-bonded hydrogen atoms per molecule>>
The component (B-1) functions as a crosslinking agent for the component (A). The component (B-1) is typically a compound represented by the general formula (II):
(R ¹³ ) _c H _d SiO _(4-c1-d1)/2 (II)
(In the formula,
R ¹³ represents a monovalent hydrocarbon group having no aliphatic unsaturated bonds;
c1 is an integer from 0 to 2;
d1 is an integer from 1 to 3, provided that c1+d1 is an integer from 1 to 3.
The molecule has two or more units represented by the following formula:

R ¹³ is preferably a methyl group from the viewpoint of ease of synthesis, and d1 is preferably 1 from the viewpoint of ease of synthesis.

For ease of synthesis, component (B-1) preferably has three or more siloxane units. Furthermore, because it does not volatilize even when heated to the curing temperature, has excellent fluidity, and is easily mixed with component (A), the number of siloxane units in component (B-1) is preferably 6 to 200, and particularly preferably 10 to 150. From the perspective of efficiently functioning as a crosslinking agent for component (A), component (B-1) preferably has three or more units represented by general formula (II) in its molecule.

The siloxane skeleton in component (B-1) may be linear, branched, or cyclic, with linear being preferred. In component (B-1), the hydrogen atoms bonded to the silicon atoms may be present at the terminals or in the intermediate units, but are preferably present in the intermediate units.

The component (B-1) is preferably (B-1-1) a linear polyorganohydrogensiloxane in which both ends are each independently blocked with R ¹⁴ ₃ SiO _1/2 units and the intermediate unit is composed only of R ¹⁴ ₂ SiO _2/2 units, or (B-1-2) a polyorganohydrogensiloxane composed only of R ¹⁴ ₃ SiO _1/2 units and SiO _4/2 units (in each of the above formulas, R ¹⁴ is each independently a hydrogen atom or a monovalent hydrocarbon group not containing an aliphatic unsaturated bond, with the proviso that at least three of the R ^14s are hydrogen atoms).

In the case of components (B-1-1) and (B-1-2), examples of the R ¹⁴ ₃ SiO _1/2 unit include HR ¹⁵ ₂ SiO _1/2 units and R ¹⁵ ₃ SiO _1/2 units, and examples of the R ¹⁴ ₂ SiO _2/2 units include HR ¹⁵ SiO _2/2 units and R ¹⁵ ₂ SiO _2/2 units (in each of the above formulas, R ¹⁵ is a monovalent hydrocarbon group having no aliphatic unsaturated bonds).

The component (B-1) is particularly preferably a linear polyorganohydrogensiloxane in which both ends are blocked with M ^H units (dimethylhydrogensiloxane units) and the intermediate units are composed only of D units (dimethylsiloxane units) and D ^H units (dimethylsiloxane units), or a linear polyorganohydrogensiloxane in which both ends are blocked with M ^H units (dimethylhydrogensiloxane units) and the intermediate units are composed only of D units (dimethylsiloxane units).

<<Polyorganohydrogensiloxanes other than component (B-1)>>
The component (B) may contain a component (B) other than the component (B-1) (hereinafter also referred to as the component (B-2)). The component (B-2) may be a polyorganohydrogensiloxane having one hydrogen atom bonded to a silicon atom in the molecule. The siloxane skeleton in the component (B-2) may be linear, branched, or cyclic, with a linear structure being preferred. Furthermore, in the component (B-2), the hydrogen atom bonded to the silicon atom may be present at the terminal or in an intermediate unit.

The component (B-2) is particularly preferably a linear polyorganohydrogensiloxane represented by M ^HD _n M.

<Preferred Embodiments of Component (B)>
The viscosity of component (B) at 23°C is preferably 0.01 to 500 mPa·s, more preferably 1 to 300 mPa·s, and particularly preferably 5 to 100 mPa·s. When the viscosity of component (B) is within this range, component (E) and the polymer components (components (A) and (B)) can be easily kneaded together in the production process, resulting in a composition with better electrical insulation properties, BLT properties, dischargeability, and heat dissipation properties. The viscosity is as described above for component (A).

Component (B) may be a single component or a combination of two or more components. For example, component (B) may consist of only two or more (B-1) components, or may be a mixture of one or more (B-1) components and one or more (B-2) components.

<Preferred embodiments of component (A) and component (B)>
From the viewpoints of curability and heat resistance, as well as controlling the hardness of the material, it is preferable that the thermally conductive silicone composition further contains at least one member selected from the group consisting of (A-2) a polyorganosiloxane having one silicon-bonded alkenyl group per molecule, and (B-2) a polyorganohydrogensiloxane having one silicon-bonded hydrogen atom per molecule.

<(C) Platinum-based catalyst>
The platinum catalyst (C) is a catalyst that promotes the addition reaction between the alkenyl groups in component (A) and the hydrosilyl groups in component (B).

Examples of component (C) include platinum compounds such as chloroplatinic acid, reaction products of chloroplatinic acid and alcohol, platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-ketone complexes, and platinum-phosphine complexes. Of these, platinum-vinylsiloxane complexes are preferred because of their excellent catalytic activity, and Karstedt complexes, platinum-1,1,3,3-tetramethyl-1,3-divinyldisiloxane complexes (platinum-methylvinylsiloxane dimer complexes), Ashley complexes, and platinum-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane complexes (platinum-methylvinylsiloxane tetramer complexes) are particularly preferred because they cure in a short time at room temperature.
The component (C) may be one type of component or a combination of two or more types of components.

<(D) Siloxane Compound Represented by General Formula (1)>
The component (D) is represented by the following general formula (1):

[During the ceremony,
R ¹ : a group having an alkoxysilyl group having 1 to 4 carbon atoms; R ² : a group represented by the following general formula (2):

(wherein R4 ^'s are each independently a monovalent hydrocarbon group having 1 to 12 carbon atoms; Y is a group selected from the group consisting of R4 ^'s and aliphatic unsaturated groups; and d is an integer from 2 to 60); X's are each independently a divalent hydrocarbon group having 2 to 10 carbon atoms; a and b are each independently an integer of 1 or greater; c is an integer of 0 or greater; a+b+c is an integer of 4 or greater; and ^R3 's are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom.
It is shown as follows.

In component (D), the units containing ^R1 , the units containing ^R2 , and the units represented by ^SiR32O do not necessarily have to be arranged as shown in the above general formula (1 _{) ;} for example, a unit represented by ^SiR32O may be present between the units containing ^R1 and the units containing ^R2 .

Siloxane compounds having a cyclic structure represented by general formula (1) can incorporate many hydrolyzable groups into the cyclic structure, and because these groups are concentrated in a specific location, it is believed that this increases the processing efficiency of component (E) and enables higher loadings. Additionally, the siloxane compound itself has high heat resistance, imparting high heat resistance to the thermally conductive silicone composition. Another advantage of siloxane compounds represented by general formula (1) is that they can be easily obtained, for example, by the addition reaction of a cyclic siloxane containing a hydrogen group with a siloxane having a vinyl group at one end, or a silane compound containing a vinyl group and a hydrolyzable group.

^R1 is a group having an alkoxysilyl group having 1 to 4 carbon atoms, and is a hydrolyzable functional group. ^R1 may be bonded directly to X via silicon, or may be bonded via a linking group such as an ester bond. ^R1 is preferably a group having the following structure:

^R1 is preferably a group having a structure containing two or more, particularly three, alkoxysilyl groups, since this tends to further improve the processing efficiency of the thermally conductive filler. Furthermore, ^R1 preferably contains a methoxysilyl group, since the raw material can be easily obtained.

^R2 is a linear organosiloxy group represented by general formula (2). In general formula (2), the number d is an integer from 2 to 60. Having a number d between 2 and 60 enhances the effect on fluidity, enables high compounding, and reduces the viscosity of the siloxane compound itself. Each ^R4 is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, such as a linear or branched _C1-12 alkyl group or an aryl group such as phenyl or naphthyl. The hydrocarbon group may also be substituted with a halogen atom such as chlorine, fluorine, or bromine. Examples of such a group include perfluoroalkyl groups such as trifluoromethyl. For ease of synthesis, ^R4 is preferably a methyl group. Y is a group selected from the group consisting of ^R1 , ^R4 , and an aliphatic unsaturated group. The aliphatic unsaturated group preferably has 2 to 10 carbon atoms, and more preferably has 2 to 6 carbon atoms. Furthermore, the aliphatic unsaturated group preferably has a double bond at its terminal, since this facilitates the curing reaction.Y is preferably a methyl group or a vinyl group, since synthesis is easy.

^R1 and ^R2 are bonded to the cyclic siloxane portion of the siloxane represented by general formula ₍ 1 ₎ via the group X. The group X is a divalent hydrocarbon group having 2 to 10 carbon atoms, and examples of the _group X include alkylene groups such as _{-CH2CH2- , -CH2CH2CH2-} , _{-CH2CH2CH2CH2CH2CH2CH2-} , _-CH2CH ( _CH3 )- _, and _{-CH2CH ( CH3} ) _CH2- . From the _viewpoint of _{ease of} synthesis, X is preferably _-CH2CH2- or _-CH2CH ( _CH3 )-.

Each ^R3 is independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom. Each ^R3 may be the same or different. For ease of synthesis, ^R3 is preferably a methyl group or a hydrogen atom.

a is an integer of 1 or greater, preferably 1. b is an integer of 1 or greater, preferably 1 or 2. c is an integer of 0 or greater, preferably 0 to 2. The sum of a + b + c is an integer of 4 or greater, but is preferably 4 for ease of synthesis.

Specific examples of the siloxane compound include compounds represented by the following structural formulas:

Component (D) may be a single component or a combination of two or more components.

<(E) Thermally conductive filler>
(E) The thermally conductive filler is selected from the following:
(E-1) Silicon carbide having a particle size distribution peak in the range of 10 μm or more and 40 μm or less;
(E-2) a first thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of 0.1 μm to 1.0 μm;
(E-3) a second thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of more than 1.0 μm and less than 10 μm, and (E-4) a third thermally conductive filler (excluding silicon carbide) having a thermal conductivity of 60 W/mK to 300 W/mK and a particle size distribution peak in the range of 10 μm or more and 40 μm or less.

<(E-1) Silicon carbide having a particle size distribution peak in the range of 10 μm to 40 μm>
Component (E-1) is silicon carbide having a particle size distribution peak in the range of 10 μm to 40 μm. The silicon carbide is not particularly limited as long as it is of a grade usable as a thermally conductive filler, and commercially available silicon carbide can be used. Examples of commercially available silicon carbide include black silicon carbide and green silicon carbide manufactured by Pacific Random Corporation. Ultrafinely powdered versions of these silicon carbides can also be used.

When component (E-1) has a monodisperse particle size distribution, the peak of the silicon carbide particle size distribution and the average particle size are synonymous. The average particle size can be determined as the weight average value (or median diameter), for example, using a particle size distribution measuring device using laser diffraction or other methods.

The component (E-1) preferably has a monodisperse particle size distribution. The thermally conductive component (E-1) preferably has a particle size distribution peak in the range of 15 μm to 35 μm, and particularly preferably in the range of 20 μm to 30 μm. From the viewpoints of electrical insulation properties, BLT properties, ejection properties, and heat dissipation properties, the BET specific surface area of the component (E-1) is preferably 0.01 to 5.0 m ² /g, and particularly preferably 0.5 to 3.0 m ² /g. The component (E-1) may be a single component or a combination of two or more components.

Silicon carbide can be used as component (E-2) and/or component (E-3), which will be described later. When silicon carbide is used as component (E-2) and/or component (E-3), the silicon carbide contained in the composition can have at least two peaks in its particle size distribution, i.e., a polydisperse particle size distribution. That is, the thermally conductive silicone composition can contain, as component (E-1), silicon carbide having a peak in its particle size distribution in the range of 10 μm to 40 μm, as well as, as component (E-2), silicon carbide having a peak in its particle size distribution in the range of 0.1 μm to 1.0 μm, and/or, as component (E-3), silicon carbide having a peak in its particle size distribution in the range of more than 1.0 μm to less than 10 μm.

<<(E-2) First thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of 0.1 μm to 1.0 μm>>
The thermal conductivity of component (E-2) is a value measured by a laser flash method, and the peak of the particle size distribution is as described above for component (E-1).
The component (E-2) is not particularly limited and can be appropriately selected from known components. The component (E-2) is preferably alumina (thermal conductivity: 30 W/mK), aluminum nitride (thermal conductivity: 180 W/mK), aluminum hydroxide (thermal conductivity: 11 W/mK), magnesium oxide (thermal conductivity: 60 W/mK), zinc oxide (thermal conductivity: 25 W/mK), crystalline silica (thermal conductivity: 10 W/mK), aluminum (thermal conductivity: 250 W/mK), boron nitride (thermal conductivity: 60 to 200 W/mK), or graphitized carbon (thermal conductivity: 100 to 250 W/mK).
From the viewpoints of electrical insulation properties, BLT properties, ejection properties, and heat dissipation properties, the BET specific surface area of component (E-2) is preferably 0.01 to 5 m ² /g, and particularly preferably 0.1 to 1 m ² /g.
The component (E-2) may be a single component or a combination of two or more components.

<<(E-3) Second thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of more than 1.0 μm and less than 10 μm>>
The thermal conductivity of component (E-3) is as described above for component (E-2), and the peak of the particle size distribution is as described above for component (E-1).

The component (E-3) is not particularly limited and can be appropriately selected from known components. The component (E-3) is preferably alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, crystalline silica, aluminum, boron nitride, or graphitized carbon.
From the viewpoints of electrical insulation properties, BLT properties, ejection properties, and heat dissipation properties, the BET specific surface area of the component (E-3) is preferably 0.1 to 3.0 ^{m 2} /g, and particularly preferably 0.5 to 2.0 m ² /g.
The component (E-3) may be one type of component or a combination of two or more types of components.

<<(E-4) A third thermally conductive filler (excluding silicon carbide) having a thermal conductivity of 60 W/mK to 300 W/mK and a particle size distribution peak in the range of 10 μm or more and 40 μm or less>>
The thermal conductivity of component (E-4) is as described above for component (E-2), and the peak of the particle size distribution is as described above for component (E-1).

The component (E-4) is not particularly limited and can be appropriately selected from known components. The component (E-4) is preferably aluminum nitride, boron nitride, or graphitized carbon.
From the viewpoints of electrical insulation properties, BLT properties, ejection properties, and heat dissipation properties, the BET specific surface area of component (E-4) is preferably 0.01 to 1.0 ^{m 2} /g, and particularly preferably 0.1 to 0.5 m ² /g.
The component (E-4) may be one type of component or a combination of two or more types of components.

<(E-5) Other thermally conductive fillers>
In addition to the components (E-1) to (E-4), the component (E) may also contain (E-5) another thermally conductive filler.

Examples of component (E-5) include thermally conductive fillers (e.g., silicon carbide, aluminum nitride) having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of more than 40 μm; and thermally conductive fillers having a thermal conductivity of 10 W/mK or more but less than 60 W/mK and a particle size distribution peak in the range of 10 μm or more and 40 μm or less. From the viewpoints of electrical insulation properties, BLT properties, dischargeability, and heat dissipation, the BET specific surface area of component (E-5) is preferably 0.1 to 3.0 ^{m 2} /g, and particularly preferably 0.5 to 2.0 m ² /g.

Component (E-5) may be one type or a combination of two or more types.

<(F) Additional Components>
The composition may contain further components (F) such as a reaction inhibitor, an organic solvent, an adhesion promoter, an inorganic pigment, an organic pigment, a thixotropy-imparting agent, a viscosity modifier, an ultraviolet protection agent, an antifungal agent, a heat resistance improver, and a flame retardant, as long as the effects of the present invention are not impaired. Each of the components (F) may be one type or a combination of two or more types.

<<Reaction inhibitor>>
Examples of the reaction inhibitor include organic compounds having a polar group in the molecule, such as diallyl maleate, and organic compounds having an unsaturated bond, such as acetylene alcohols and their derivatives. The reaction inhibitor suppresses the curing reaction rate of the composition, contributing to improving the workability in handling and the balance between the development of adhesiveness and the curing rate.

<<Organic solvents>>
The organic solvent is a component that can dissolve or disperse the components contained in the composition. Examples of the organic solvent include aromatic organic solvents such as toluene and xylene.

<<Other (F) Additional Ingredients>>
Component (F), other than the reaction inhibitor and organic solvent, can be appropriately selected from components used in thermally conductive silicone compositions.

[Content]
The content of each component in the thermally conductive silicone composition is as follows:
The total content of components (A) to (D) per 100 parts by mass of component (E) is 1.0 to 10.0 parts by mass. When the total content of components (A) to (D) per 100 parts by mass of component (E) is less than 1.0 part by mass, the thermal conductivity tends to be high, but the amount of polymer relative to component (E) is too small, raising concerns that the composition may not form a paste. When the total content of components (A) to (D) per 100 parts by mass of component (E) exceeds 10.0 parts by mass, the ejection properties are good but the thermal conductivity is low. The total content of components (A) to (D) per 100 parts by mass of component (E) is preferably 2.0 to 8.0 parts by mass, and particularly preferably 3.0 to 7.0 parts by mass. Alternatively, the total content of components (A) to (D) per 100 parts by mass of component (E) may be 6.0 to 8.0 parts by mass.

The content of component (E-2) is 28.0 parts by mass or less per 100 parts by mass of component (E). If the content of component (E-2) exceeds 28.0 parts by mass per 100 parts by mass of component (E), the composition will not hold together. From the viewpoints of electrical insulation properties, BLT properties, dischargeability, and heat dissipation, the content of component (E-2) is preferably 10.0 to 28.0 parts by mass, and particularly preferably 15.0 to 25.0 parts by mass per 100 parts by mass of component (E).

[Preferable content]
The content of each component in the thermally conductive silicone composition is preferably as follows:

From the viewpoints of electrical insulation properties, BLT properties, ejection properties, and heat dissipation properties, the content of component (E-1) per 100 parts by mass of component (E) is preferably 5.0 to 30.0 parts by mass, more preferably 10.0 to 30.0 parts by mass, and particularly preferably 10.0 to 25.0 parts by mass.

From the viewpoints of electrical insulation properties, BLT properties, dischargeability, and heat dissipation, the content of component (E-3) is preferably 15.0 to 40.0 parts by mass, and particularly preferably 20.0 to 35.0 parts by mass, per 100 parts by mass of component (E).

From the viewpoints of electrical insulation properties, BLT properties, ejection properties, and heat dissipation properties, the content of component (E-4) is preferably 5.0 to 40.0 parts by mass, and particularly preferably 20.0 to 35.0 parts by mass, per 100 parts by mass of component (E).

Therefore, it is preferable that, per 100 parts by mass of component (E), the content of component (E-1) is 5.0 to 30.0 parts by mass, the content of component (E-2) is 10.0 to 28.0 parts by mass, the content of component (E-3) is 15.0 to 40.0 parts by mass, and the content of component (E-4) is 5.0 to 40.0 parts by mass.

From the viewpoint of ejection properties and curing characteristics, the content of component (A) is preferably 55.0 to 95.0 parts by mass, more preferably 60.0 to 90.0 parts by mass, and particularly preferably 65.0 to 85.0 parts by mass, per 100 parts by mass of the total of components (A), (B), (C), (D), and (F).

There are no particular restrictions on the amount of component (B) contained, so long as it is an amount that results in the formation of a network structure in the cured product of the thermally conductive silicone composition. An amount such that the ratio (H/Vi) of the number of hydrogen atoms bonded to silicon atoms in component (B) to the number of alkenyl groups in component (A), Vi, is 0.1 or greater and less than 3.5 is preferred, an amount between 0.2 and 2.5 is more preferred, and an amount between 0.3 and 2.0 is particularly preferred.

The content of component (C) is a catalytic amount relative to the total amount of the thermally conductive silicone composition. Specifically, from the standpoint of curability, the content of component (C) is preferably 0.1 to 1,000 ppm by weight, and particularly preferably 0.5 to 200 ppm by weight, calculated as platinum metal atoms, per 100 parts by weight of components (A), (B), (C), (D), and (F) combined.

The amount of component (F) is not particularly limited as long as it does not impair the intended use of the thermally conductive silicone composition.

(Method for producing thermally conductive silicone composition)
The thermally conductive silicone composition can be produced by uniformly kneading the essential components (A) through (E) and the optional component (F) using a mixing means such as a universal mixer or kneader.

(cured product)
A cured product obtained by curing a thermally conductive silicone composition can be obtained by curing the thermally conductive silicone composition. The curing conditions (i.e., heating temperature and heating time) can be adjusted appropriately to suit the heat resistance temperature of the component to which the thermally conductive silicone composition is applied. From the viewpoints of heat resistance and operability of the component, the heating temperature is preferably 20 to 150°C, and more preferably greater than 23°C and not greater than 100°C. The heating time depends on the amount of material used to be cured and the heating output of the curing equipment, but from the viewpoint of simplicity of the curing process, it is preferably 15 minutes to 3 hours, and more preferably 30 minutes to 2 hours.

(Application)
The cured product obtained by curing the thermally conductive silicone composition can be used as a heat dissipation component for electronic devices, integrated circuit devices, and other electronic components. Therefore, electronic components containing the thermally conductive silicone composition are also within the scope of the present invention.

The present invention will be described in more detail below with reference to examples and comparative examples. In these examples, parts refer to parts by mass, and viscosity refers to viscosity at 23°C. The present invention is not limited to these examples.

(Ingredients used)
The components used in the examples and comparative examples are as follows.
(A) Polyorganosiloxane having alkenyl groups bonded to silicon atoms (A-1): a linear vinyldimethylpolysiloxane terminated at both ends, represented by M ^vi D _n M ^vi , and having a viscosity of 0.5 Pa s. (A-2): a linear vinyldimethylpolysiloxane terminated at one end, represented by M ^vi D _n M, and having a viscosity of 0.03 Pa s.

(B) Polyorganohydrogensiloxane (B-1) having a hydrogen atom bonded to a silicon atom: Single-terminated hydrogenpolysiloxane: a linear polymethylhydrogensiloxane represented by M ^HD _n M (effective hydrogen content 0.04 mmol/g, viscosity 0.02 mPa s)
(B-2): Dual-end hydrogen polysiloxane: a linear polymethylhydrogen siloxane represented by M ^HD _n M ^H (effective hydrogen content 1.2 mmol/g, viscosity 10 mPa s)
(B-3): Both-end side chain hydrogen polysiloxane: a linear polymethylhydrogen siloxane in which both ends are blocked with M ^H units and the intermediate units consist only of D units and D ^H units (effective hydrogen content 2.6 mmol/g, viscosity 20 mPa s).

(C) Platinum catalyst (C-1): Karstedt catalyst (platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, 2.0% by mass in terms of platinum atoms)

(D) Siloxane compound (D-1):

A mixture of cyclic siloxane compounds (n=10 to 50) represented by the formula:

(E) Thermally conductive filler Since the thermally conductive fillers used in the examples were monodisperse, the peak diameter of the particle size distribution of the thermally conductive fillers used in the examples is synonymous with the "average particle diameter." Furthermore, the "particle diameter" in the tables refers to the "peak diameter of the particle size distribution."
(E-1) Silicon carbide having a particle size distribution peak in the range of 10 μm to 40 μm (E-1-1): Silicon carbide (having a particle size distribution peak at 20 μm, thermal conductivity 200 W/mK, BET specific surface area 0.2 m ² /g, supplier name: Shinano Electric Smelting Co., Ltd.)
(E-1-2): Silicon carbide (having a particle size distribution peak at 25 μm, thermal conductivity 200 W/mK, BET specific surface area 0.1 m ² /g, supplied by Shinano Electric Smelting Co., Ltd.)
(E-1-3): Silicon carbide (having a particle size distribution peak at 30 μm, thermal conductivity 200 W/mK, BET specific surface area 0.1 m ² /g, supplied by Shinano Electric Smelting Co., Ltd.)
(E-2): First thermally conductive filler (E-2-1): Zinc oxide (having a particle size distribution peak at 0.1 μm, thermal conductivity 25 W/mK, BET specific surface area 9.0 ^{m 2} /g, supplied by Zochem LLC)
(E-2-2): Aluminum nitride (having a particle size distribution peak at 0.1 μm, thermal conductivity 180 W/mK, BET specific surface area 2.8 m ² /g, supplied by Tokuyama Corporation)
(E-2-3): Alumina (having a particle size distribution peak at 0.5 μm, thermal conductivity 30 W/mK, BET specific surface area 4.6 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-2-4): Silicon carbide (having a particle size distribution peak at 0.5 μm, thermal conductivity 200 W/mK, BET specific surface area 5.0 m ² /g, supplied by Shinano Electric Refining Co., Ltd.)
(E-2-5): Alumina (having a particle size distribution peak at 0.3 μm, thermal conductivity 30 W/mK, BET specific surface area 7.2 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-2-6): Alumina (having a particle size distribution peak at 0.8 μm, thermal conductivity 30 W/mK, BET specific surface area 2.1 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-3): Second thermally conductive filler (E-3-1): Alumina (having a particle size distribution peak at 3.0 μm, thermal conductivity 30 W/mK, BET specific surface area 0.6 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-3-2): Alumina (having a particle size distribution peak at 5.0 μm, thermal conductivity 30 W/mK, BET specific surface area 0.3 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-3-3): Silicon carbide (having a particle size distribution peak at 5.0 μm, thermal conductivity 200 W/mK, BET specific surface area 1.5 m ² /g, supplied by Shinano Electric Refining Co., Ltd.)
(E-3-4): Alumina (having a particle size distribution peak at 2.0 μm, thermal conductivity 30 W/mK, BET specific surface area 1.0 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-3-5): Alumina (having a particle size distribution peak at 7.0 μm, thermal conductivity 30 W/mK, BET specific surface area 0.4 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-4): Third thermally conductive filler (E-4-1): Aluminum nitride (having a particle size distribution peak at 25 μm, thermal conductivity 180 W/mK, BET specific surface area 0.2 m ² /g, supplied by Toyo Aluminum K.K.)
(E-5): Other thermally conductive fillers (E-5-1): Silicon carbide (having a particle size distribution peak at 60 μm, thermal conductivity 200 W/mK, BET specific surface area 0.2 m ² /g, supplied by Shinano Electric Refining Co., Ltd.)
(E-5-2): Alumina (having a particle size distribution peak at 25 μm, thermal conductivity 30 W/mK, BET specific surface area 0.1 m ² /g, supplied by Sumitomo Chemical Co., Ltd.)
(E-5-3): Aluminum nitride (having a particle size distribution peak at 60 μm, thermal conductivity 180 W/mK, BET specific surface area 0.1 m ² /g, supplied by Toyo Aluminum K.K.)

(F) Other Components (F-1) Reaction Inhibitor Dimethylbis(1,1-dimethyl-2-propynyloxy)silane (Supplier: Momentive Performance Materials Japan, LLC)

(1) Preparation of Base Polymer (1) (Silicone Composition 1 Excluding Filler) The base polymers to be compounded in the Examples and Comparative Examples were kneaded using a planetary mixer in the compositions shown in Table 1 to prepare base polymer (1).

(2) Preparation of Base Polymer (2) (Silicone Composition 2 Excluding Filler) Base polymer (2) was prepared using the composition shown in Table 2 in the same manner as base polymer (1).

(3) Preparation of Thermally Conductive Silicone Compositions Examples 1 to 20 and Comparative Examples 1 to 13
Thermally conductive silicone compositions were prepared by blending the thermally conductive fillers and base polymers according to the compositions shown in Tables 3 to 13 and kneading them using a planetary mixer.

(Evaluation method)
1. Thermal Conductivity Using a thermal conductivity meter (TPS 1500) (Kyoto Electronics Manufacturing Co., Ltd.), a plastic container with an inner diameter of 30 mm and a depth of 10 mm was filled with the composition and left at 70°C for 1 hour to harden the composition, producing a sample. The thermal conductivity was measured by sandwiching the sensor of the thermal conductivity meter between two of the obtained samples. The heat dissipation was evaluated according to the following criteria. A thermal conductivity of 7.0 W/(m K) or more was determined to have excellent heat dissipation.

2. Flow rate (dischargeability)
The flow rate (g/min) of the composition was measured as follows and used to evaluate the dischargeability.
(1) A 30 cc EFD syringe manufactured by Nordson Corporation was filled with the composition.
(2) A high-precision dispenser with a correction function, SuperΣxIII, manufactured by Musashi Engineering Co., Ltd., was used as the dispenser, and the composition was dispensed at 0.625 MPa for 1 minute.
(3) The amount of the composition discharged was measured to determine the flow rate (g/min) of the composition.
When the flow rate was 20 g/min or more, it was determined that the ejection properties were excellent.

3. BLT
The BLT, i.e., the bond line thickness of the heat dissipation material, was measured as follows. Two 10 mm x 10 mm silicon chips were prepared, and their thicknesses were measured in advance. 0.01 ml of the composition was applied to the silicon chips after the thickness measurement, and then the silicon chips were sandwiched together. A load of 100 N was applied, and the chips were then left at 70°C for 1 hour. The thickness was measured using a micrometer. The BLT thickness was calculated by subtracting the thickness of the two silicon chips from the thickness after the thickness measurement.
A composition was considered to have a low BLT if the BLT was 60 μm or less.

4. Breakdown Voltage Breakdown voltage was measured in accordance with JIS K 6249. Breakdown voltage was measured using an electrical insulating oil breakdown voltage tester, Portatest A-2 (manufactured by Soken Denki Co., Ltd.). The composition was cured at 70°C for 1 hour, and a test piece adjusted to a thickness of 1 mm was applied with a voltage of 2 kV/sec. The voltage at which the test piece became conductive and lost its electrical insulation was taken as the breakdown voltage. A breakdown voltage of 1.0 kV/mm or more was determined to be excellent in electrical insulation.

5. Volume Resistivity The volume resistivity was measured in accordance with JIS K 6249. Specifically, the volume resistivity was measured using an Advantest R8340 Digital Ultra-High Resistance/Micro-Current Meter (Advantest Corporation). The composition was cured at 70°C for 1 hour, and a test piece adjusted to a thickness of 1 mm was subjected to application of a voltage of 500 V, and the volume resistivity was calculated from the current value obtained as the response value. A composition with a volume resistivity of 1.00 x ¹⁰ Ω cm or more was determined to have excellent electrical insulation properties.

As is clear from the table, the thermally conductive silicone compositions of the examples had low BLT and were excellent in electrical insulation, dischargeability, and heat dissipation. In other words, by adjusting the content of component (E) relative to the total content of components (A) to (D), and the content of component (E-2) relative to the content of component (E), within specified ranges, it was possible to adjust the thermal conductivity and dischargeability while maintaining the BLT properties.
In particular, when Example 1 is compared with Example 10, when the amount of the "silicone composition excluding filler" is large (i.e., when the total content of components (A) to (D) is 6.0 parts by mass or more per 100 parts by mass of component (E)), the BLT is lower and the ejection properties and heat dissipation properties are superior.
Comparing Examples 1 to 3, when the amount of component (E-1) was large, the heat dissipation properties were superior.
Comparing Examples 1 and 2, when the amount of component (E-1) was small, the electrical insulation was superior. Furthermore, compared to Example 3, Examples 1 and 2 had lower BLT and superior dischargeability.
Comparing Examples 1, 4, and 7, when the particle size of component (E-1) was large, the thermal conductivity was superior. Among Examples 1 to 9, Examples 1, 4, and 7 had lower BLT and superior dischargeability.

The composition of Comparative Example 1 did not contain the component (E-4), and therefore the composition of Comparative Example 1 was inferior to the compositions of Examples 1 to 3 in terms of ejection properties and electrical insulation properties.
The composition of Comparative Example 2 does not contain component (E-4). Furthermore, the composition of Comparative Example 2 contains a thermally conductive filler with a larger particle size distribution peak than component (E-4). Therefore, the composition of Comparative Example 2 had inferior dischargeability to the composition of Example 1.
The relationship between Examples 4 to 6 and Comparative Example 3, and the relationship between Examples 7 to 9 and Comparative Example 5 are similar to the relationship between Examples 1 to 3 and Comparative Example 1. Furthermore, the relationship between Example 4 and Comparative Example 4, and the relationship between Example 7 and Comparative Example 6 are similar to the relationship between Example 1 and Comparative Example 2.
The composition of Comparative Example 7 did not contain the components (E-1) and (E-4), and therefore the composition of Comparative Example 7 did not come together as a composition.
The composition of Comparative Example 8 did not contain the components (E-1) and (E-4). The composition of Comparative Example 4 contained silicon carbide having a larger peak in the particle size distribution than the component (E-1). Therefore, the composition of Comparative Example 8 was inferior to the composition of Example 1 in terms of ejection properties and electrical insulation properties.
The composition of Comparative Example 9 contained a thermally conductive filler with lower thermal conductivity than the component (E-4), and therefore the composition of Comparative Example 9 had poor thermal conductivity.
The composition of Comparative Example 10 did not contain the component (E-4), and therefore the composition of Comparative Example 10 was inferior to the composition of Example 10 in terms of ejection properties and electrical insulation properties.
The composition of Comparative Example 11 did not contain the component (E-4), and therefore the composition of Comparative Example 11 was inferior to the composition of Example 11 in terms of ejection properties and electrical insulation properties.
In the compositions of Comparative Examples 12 and 13, the content of component (E-2) exceeded 28.0 parts by mass per 100 parts by mass of the thermally conductive filler, and therefore the compositions of Comparative Examples 12 and 13 did not form a cohesive composition.

Claims (10)

(A) a polyorganosiloxane having an alkenyl group bonded to a silicon atom;
(B) a polyorganohydrogensiloxane having a hydrogen atom bonded to a silicon atom;
(C) platinum-based catalyst;
(D) the following general formula (1):

[During the ceremony,
R ¹ : a group selected from the group consisting of the following groups:

R ² : The following general formula (2):

(wherein R ⁴ 's are each independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, and the alkyl group, cycloalkyl group, aryl group, and aralkyl group are unsubstituted or substituted with a halogen or a cyano group; Y is R ⁴ , and d is an integer of 2 to 60); X's are each independently -CH ₂ CH _{2 -} , -CH 2 CH 2 CH 2 _- , -CH ₂ CH ₂ CH ₂ CH ₂ CH _{2 -} , -CH 2 _CH ( CH 3 _{) -} , or -CH ₂ CH(CH ₃ )CH ₂ -
a and b: each independently an integer of 1 or greater; c: an integer of 0 or greater; a+b+c: an integer of 4 or greater; and R ³ : each independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 carbon atoms, wherein the alkyl group, the cycloalkyl group, and the aryl group are unsubstituted or substituted with a halogen or a cyano group .
and (E) a thermally conductive filler,
A thermally conductive silicone composition comprising:
The component (A) includes (A-1) a polyorganosiloxane having two or more silicon-bonded alkenyl groups in the molecule,
The component (B) includes (B-1) a polyorganohydrogensiloxane having two or more silicon-bonded hydrogen atoms in the molecule,
The component (E) is
(E-1) Silicon carbide having a particle size distribution peak in the range of 10 μm or more and 40 μm or less;
(E-2) a first thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of 0.1 μm to 1.0 μm;
(E-3) a second thermally conductive filler having a thermal conductivity of 10 W/mK to 300 W/mK and a particle size distribution peak in the range of more than 1.0 μm and less than 10 μm, and (E-4) a third thermally conductive filler (excluding silicon carbide) having a thermal conductivity of 60 W/mK to 300 W/mK and a particle size distribution peak in the range of 10 μm or more and 40 μm or less,
the total content of components (A), (B), and (C) is 1.0 to 10.0 parts by mass per 100 parts by mass of component (E); and
A thermally conductive silicone composition, in which the amount of component (E-2) is 28.0 parts by mass or less per 100 parts by mass of component (E). the component (E-2) is at least one selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, crystalline silica, aluminum, boron nitride, and graphitized carbon;
The component (E-3) is at least one selected from the group consisting of alumina, aluminum nitride, aluminum hydroxide, magnesium oxide, zinc oxide, crystalline silica, aluminum, boron nitride, and graphitized carbon; and
2. The thermally conductive silicone composition according to claim 1, wherein component (E-4) is at least one member selected from the group consisting of aluminum nitride, boron nitride, and graphitized carbon. The thermally conductive silicone composition according to claim 1 further comprises at least one member selected from the group consisting of (A-2) a polyorganosiloxane having one silicon-bonded alkenyl group per molecule, and (B-2) a polyorganohydrogensiloxane having one silicon-bonded hydrogen atom per molecule. The thermally conductive silicone composition according to claim 2 further comprises at least one member selected from the group consisting of (A-2) a polyorganosiloxane having one silicon-bonded alkenyl group per molecule, and (B-2) a polyorganohydrogensiloxane having one silicon-bonded hydrogen atom per molecule. For 100 parts by mass of component (E),
The content of the component (E-1) is 5.0 to 30.0 parts by mass,
The content of the component (E-2) is 10.0 to 28.0 parts by mass,
The content of the component (E-3) is 15.0 to 40.0 parts by mass, and the content of the component (E-4) is 5.0 to 40.0 parts by mass.
The thermally conductive silicone composition according to claim 1 . For 100 parts by mass of component (E),
The content of the component (E-1) is 5.0 to 30.0 parts by mass,
The content of the component (E-2) is 10.0 to 28.0 parts by mass,
The content of the component (E-3) is 15.0 to 40.0 parts by mass, and the content of the component (E-4) is 5.0 to 40.0 parts by mass.
The thermally conductive silicone composition according to claim 2. For 100 parts by mass of component (E),
The content of the component (E-1) is 5.0 to 30.0 parts by mass,
The content of the component (E-2) is 10.0 to 28.0 parts by mass,
The content of the component (E-3) is 15.0 to 40.0 parts by mass, and the content of the component (E-4) is 5.0 to 40.0 parts by mass.
The thermally conductive silicone composition according to claim 3. For 100 parts by mass of component (E),
The content of the component (E-1) is 5.0 to 30.0 parts by mass,
The content of the component (E-2) is 10.0 to 28.0 parts by mass,
The content of the component (E-3) is 15.0 to 40.0 parts by mass, and the content of the component (E-4) is 5.0 to 40.0 parts by mass.
The thermally conductive silicone composition according to claim 4. A cured product obtained by curing the thermally conductive silicone composition described in any one of claims 1 to 8. An electronic component comprising the thermally conductive silicone composition according to any one of claims 1 to 8.