Thermally conductive polyorganosiloxane composition

Abstract

The present invention relates to a thermally conductive polyorganosiloxane composition containing (A) a silicone gel crosslinked product having a hydrolyzable group bonded to a silicon atom, and (B) a thermally conductive inorganic filler. The thermally conductive polyorganosiloxane composition has excellent displacement resistance.

Description

Thermally conductive polyorganosiloxane composition

[0001] This invention relates to a thermally conductive polyorganosiloxane composition.

[0002] With the increasing performance and miniaturization of electronic components such as power modules and CPUs, thermal management is becoming increasingly important. Thermally conductive greases, putties, and heat dissipation sheets are used for this thermal management.

[0003] Thermal greases and putties can be applied to electronic components using application equipment, and they also offer superior heat dissipation performance compared to sheet-type materials due to their lower contact thermal resistance. However, a problem arises when the viscosity of the thermal grease is reduced to obtain good application performance: the grease can shift due to thermal shock to the component, causing a pump-out phenomenon, which results in insufficient heat removal.

[0004] One method to improve this pump-out phenomenon is to increase the elastic modulus of the heat dissipation material (heat-dissipating compound) by reinforcing it with fillers. To achieve this, it is necessary to generate an interaction between the polymer and the filler. As such a heat dissipation material, Patent Document 1 describes a heat dissipation material containing an addition-curing type silicone gel in which alkenyl groups are bonded to silicon atoms, and a thermally conductive filler.

[0005] WO2007 / 086443

[0006] The heat dissipation material described in Patent Document 1 had poor stability under thermal cycling. Specifically, the heat dissipation material exhibited significant displacement due to the heat cycle.

[0007] The present invention aims to provide a thermally conductive polyorganosiloxane composition with excellent shear resistance.

[0008] In other words, the present invention relates to the following [1] to

[13] : [1] A thermally conductive polyorganosiloxane composition comprising (A) a silicone gel crosslinked material having hydrolyzable groups bonded to silicon atoms, and (B) a thermally conductive inorganic filler. [2] Component (A) is a silicone gel crosslinked product comprising: (a) (a-1) a polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and which may also have a hydrolyzable group bonded to a silicon atom, and (a-2) an organosilane compound having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and which may also have a hydrolyzable group bonded to a silicon atom; and (b) (b-1) a polyorganosiloxane having a hydrogen atom bonded to a silicon atom and which may also have a hydrolyzable group bonded to a silicon atom, and (b-2) an organosilane compound having a hydrogen atom bonded to a silicon atom and which may also have a hydrolyzable group bonded to a silicon atom, wherein component (a) contains component (a-1) and / or component (b) contains component (b-1), The thermally conductive polyorganosiloxane composition according to [1], wherein one or both of component (a) and component (b) contain a component having a hydrolyzable group bonded to a silicon atom, and the amount of component (b) is such that for every one monovalent group having an aliphatic unsaturated bond bonded to a silicon atom in component (a), there are 0.02 to 4 hydrogen atoms bonded to a silicon atom in component (b). [3] The thermally conductive polyorganosiloxane composition according to [1] or [2], wherein the concentration of silicon atoms to which hydrolyzable groups are bonded in component (A) is 0.01 mmol / g to 20 mmol / g. [4] The thermally conductive polyorganosiloxane composition according to any one of [1] to [3], wherein the penetration degree (ASTMD1403, 1 / 4 cone) of component (A) is 10 to 200. [5] A thermally conductive polyorganosiloxane composition according to any one of [1] to [4], comprising 500 to 10,000 parts by mass of component (B) per 100 parts by mass of component (A).Component (B) is the following: (B-1) a first thermally conductive inorganic filler having an average particle diameter of 0.01 μm or more and less than 1 μm, (B-2) a second thermally conductive inorganic filler having an average particle diameter of 1 μm or more and less than 15 μm, and (B-3) a third thermally conductive inorganic filler having an average particle diameter of 15 μm or more and 500 μm or less. The content of component (B-1) is 0.01 to 99.98 parts by mass, the content of component (B-2) is 0.01 to 99.98 parts by mass, and the content of component (B-3) is 0.01 to 99.98 parts by mass with respect to 100 parts by mass in total of component (B). And the total content of component (B-1), component (B-2) and component (B-3) is 80.00 to 100 parts by mass. The thermally conductive polyorganosiloxane composition according to any one of [1] to [5]. [7] The thermally conductive polyorganosiloxane composition according to [6], wherein the shape of (B-1) is round, crushed, spherical or polyhedral. [8] The thermally conductive polyorganosiloxane composition according to [6] or [7], wherein the shape of (B-2) is round, crushed, spherical or polyhedral. [9] The thermally conductive polyorganosiloxane composition according to any one of [6] to [8], wherein the shape of (B-3) is round, crushed, spherical or polyhedral.

[10] Further, (C) a polyorganosiloxane having a viscosity at 23 °C of 1 to 10,000 mPa·s and containing a hydrolyzable group bonded to a silicon atom, and / or, R. ３ , ２ ａ R ２ ｂ Si(OR ３ )<000007> (In the formula, each R １ is independently an alkyl group having 1 to 3 carbon atoms, each R ２ is independently an alkyl group having 6 to 12 carbon atoms, each R ３A thermally conductive polyorganosiloxane composition according to any one of [1] to [9], comprising an alkylalkoxysilane represented by (a) independently being an alkyl group having 1 to 3 carbon atoms, a being 0 or 1 to 3, b being 0 or 1 to 3, provided that a + b is 1 to 3).

[11] A thermally conductive polyorganosiloxane composition according to any one of [1] to

[10] , further comprising (D) a polyorganosiloxane that does not have functional groups that react with component (A) and component (B).

[12] A thermally conductive polyorganosiloxane composition according to any one of [1] to

[11] , wherein the displacement distance after the following heat cycle test is 0 mm or more and 1 mm or less. (Heat cycle test) A test piece is obtained by sandwiching the thermally conductive polyorganosiloxane composition in a circular shape with a diameter of 1 cm between two slide glass plates (76 mm long, 26 mm wide, 1 mm thick) with a 2 mm spacer. The test specimen is placed at a 90-degree angle to the ground, and a heat cycle of 60 minutes (30 minutes at -40°C, 30 minutes at 125°C) is performed for 250 cycles. After 250 cycles, the distance the thermally conductive polyorganosiloxane composition has shifted from its original position is defined as the displacement distance. An electronic component comprising the thermally conductive polyorganosiloxane composition described in any of

[13] , [1], to

[12] .

[0009] The present invention provides a thermally conductive polyorganosiloxane composition with excellent shear resistance.

[0010] [Definition of Terms] Structural units of siloxane compounds may be described using the following abbreviations (hereinafter, these structural units will be referred to as "M unit" and "D unit," respectively). Ｈ (Sometimes referred to as "unit" etc.) M 　 : (CH ３ ) ３ SiO １／２ M Ｈ : H(CH ３ ) ２ SiO １／２ M Ｖｉ : (CH ２ =CH)(CH ３ ) ２ SiO １／２ D 　 : (CH ３) ２ SiO ２／２ D Ｈ : H(CH ３ ) SiO ２／２ D Ｖｉ : (CH ２ =CH)(CH ３ ) SiO ２／２ T 　 :CH ３ SiO ３／２ Q: SiO ４／２

[0011] In this specification, the "~" indicating a numerical range is used to mean that the numbers before and after it are included as the lower and upper limits. That is, "10 to 100 parts by mass" means "10 parts by mass or more and 100 parts by mass or less." Also, regarding numerical ranges, "or less" means "the same as or less than," and "or more" means "the same as or greater than." For example, "10 parts by mass or more and 100 parts by mass or less" includes the meanings of "more than 10 parts by mass and 100 parts by mass or less," "more than 10 parts by mass and less than 100 parts by mass," or "10 parts by mass or more and less than 100 parts by mass."

[0012] In this specification, "room temperature" means 5°C to 40°C, preferably 10°C to 35°C, and particularly preferably 23°C.

[0013] In this specification, "(A) Silicone gel crosslinked material having hydrolyzable groups bonded to silicon atoms" is also referred to as "component (A)". The same applies to "(B) Thermally conductive inorganic filler", etc.

[0014] In this specification, “hydrocarbon group” means a group obtained by removing at least one hydrogen atom from a hydrocarbon molecule containing carbon atoms and hydrogen atoms. A hydrocarbon group may be substituted with one or more substituents. Examples of substituents include halogen atoms and cyano groups. In this specification, “(meth)acryloyl group” means at least one of an acryloyl group and a methacryloyl group.

[0015] Examples of monovalent hydrocarbon groups include alkyl groups, cycloalkyl groups, aryl groups, aralkyl groups, alkenyl groups, and alkynyl groups. Examples of monovalent hydrocarbon groups that do not have an aliphatic unsaturated bond include the aforementioned monovalent hydrocarbon groups other than alkenyl groups and alkynyl groups. A monovalent group having an aliphatic unsaturated bond is a monovalent group having a carbon-carbon unsaturated bond. Examples of monovalent groups having an aliphatic unsaturated bond include alkenyl groups, alkynyl groups, (meth)acryloyl groups, and (meth)acryloyl group-containing groups. Here, examples of (meth)acryloyl group-containing groups include (meth)acryloyl groups or (meth)acryloyloxy groups bonded to a silicon atom via a carbon atom. A (meth)acryloyl group-containing group may be a group in which an alkylene group and a (meth)acryloyl group are linked by an ester bond such as a (meth)acryloyloxypropyl group.

[0016] Alkyl groups are linear or branched groups having 1 to 18 carbon atoms, including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl, and octadecyl groups. Cycloalkyl groups are monocyclic or polycyclic groups having 3 to 20 carbon atoms, including cyclopentyl, cyclohexyl, and cycloheptyl groups. Aryl groups are aromatic groups containing monocyclic or polycyclic groups having 6 to 20 carbon atoms, including phenyl, tolyl, xylyl, and naphthyl groups. Aralkyl groups are alkyl groups substituted with aryl groups, including benzyl, 2-phenylethyl, and 2-phenylpropyl groups. Alkenyl groups are linear or branched groups having 2 to 6 carbon atoms, including vinyl groups, allyl groups, propenyl groups, 3-butenyl groups, and 5-hexenyl groups. Alkynyl groups are linear or branched groups having 2 to 6 carbon atoms, including ethynyl groups, propargyl groups, 3-butynyl groups, and 5-hexynyl groups.

[0017] Alkenyl groups, alkynyl groups, alkyl groups, cycloalkyl groups, aryl groups, and aralkyl groups may be substituted with halogen atoms or cyano groups. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. Examples of alkyl groups substituted with halogen atoms include chloromethyl, bromoethyl, chloropropyl, 3,3,3-trifluoropropyl, and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups. Examples of aryl groups substituted with halogens include chlorophenyl groups. Examples of alkyl groups substituted with cyano groups include 2-cyanoethyl groups.

[0018] A divalent hydrocarbon group is a group obtained by removing one hydrogen atom from the monovalent hydrocarbon group described above. The divalent hydrocarbon group is preferably an alkylene group. An alkylene group is a linear or branched group having 1 to 18 carbon atoms, and examples include a methylene group, ethylene group, trimethylene group, 2-methylethylene group, tetramethylene group, etc.

[0019] In this specification, "hydrolyzable group" refers to -OR', -OR''OR', -OCOR', and -O-N=CR'. ２ ,-NR' ２ Examples include -NHR', halogen atoms, etc. In these formulas, R' is an alkyl group, and R'' is an alkylene group.

[0020] The hydrolyzable group is preferably -OR' (i.e., an alkoxy group) or -OR''OR' (i.e., an alkyloxyalkoxy group). R' is preferably a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group or an ethyl group. R'' is preferably a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, more preferably an unsubstituted alkylene group having 1 to 4 carbon atoms, and particularly preferably a methylene group or an ethylene group. Therefore, the hydrolyzable group is preferably a methoxy group, an ethoxy group, or a methoxyethoxy group, and particularly preferably a methoxy group or an ethoxy group.

[0021] In this specification, "a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom" is also referred to as an "unsaturated group." In this specification, "a hydrogen atom bonded to a silicon atom" is also referred to as a "Si-H group" or a "hydrosilyl group."

[0022] [Thermally conductive polyorganosiloxane composition] The thermally conductive polyorganosiloxane composition (hereinafter also simply referred to as "the composition") comprises (A) a silicone gel crosslinked material having hydrolyzable groups bonded to silicon atoms, and (B) a thermally conductive inorganic filler.

[0023] The composition exhibits excellent shear resistance. Therefore, in heat cycle tests of the composition, the minimal shearing results in superior reliability. Furthermore, the surface of component (B) typically contains functional groups that react with hydrolyzable groups. The hydrolyzable groups of component (A) react with the aforementioned functional groups of component (B), causing component (A) (a silicone gel crosslinked polymer) and component (B) (a thermally conductive inorganic filler) to interact. As a result, component (A) is reinforced by component (B), which allows the composition to have a high modulus of elasticity.

[0024] [(A) Silicone gel crosslinked material having hydrolyzable groups bonded to silicon atoms] Component (A) is a silicone gel crosslinked material having hydrolyzable groups bonded to silicon atoms. Component (A) is used as the matrix of the composition. Component (A) also imparts shear resistance to the composition.

[0025] The concentration of silicon atoms to which hydrolyzable groups are attached in component (A) is preferably 0.01 mmol / g to 20 mmol / g, more preferably 0.05 mmol / g to 15 mmol / g, and particularly preferably 0.08 mmol / g to 10 mmol / g. The concentration of silicon atoms to which hydrolyzable groups are attached in component (A) is the amount of silicon atoms to which hydrolyzable groups are attached per 1 g of component (A). When the concentration of silicon atoms to which hydrolyzable groups are attached in component (A) is within the above range, the interaction with component (B) becomes more efficient, and the shear resistance of the composition is further improved. The concentration of silicon atoms to which hydrolyzable groups are attached in component (A) can be determined by the amount charged, or by using NMR.

[0026] The penetration degree of component (A) is preferably 10 to 200, and particularly preferably 30 to 180. When the penetration degree of component (A) is within the above range, the interaction with component (B) becomes more efficient, and the workability and shear resistance of the composition tend to improve. The penetration degree of component (A) is the value measured with ASTM D1403 and a 1 / 4 cone.

[0027] Component (A) is any component as long as it has hydrolyzable groups bonded to silicon atoms. Component (A) is preferably an addition-curing type silicone gel crosslinked product. Such component (A) is as follows: (a) one or more selected from the group consisting of (a-1) a polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, and (a-2) an organosilane compound having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, and (b) one or more selected from the group consisting of (b-1) a polyorganosiloxane having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, and (b-2) an organosilane compound having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, wherein component (a) contains component (a-1) and / or component (b) contains component (b-1), One or both of component (a) and component (b) contain a component having a hydrolyzable group bonded to a silicon atom, and the amount of hydrogen atoms bonded to the silicon atom in component (b) is such that for every one monovalent group having an aliphatic unsaturated bond bonded to the silicon atom in component (a), there are 0.02 to 4 hydrogen atoms bonded to the silicon atom in component (b).

[0028] [Component (a)] Component (a) is one or more selected from the group consisting of component (a-1) and component (a-2). Here, component (a-1) is a polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom, and which may also have a hydrolyzable group bonded to a silicon atom. Component (a-2) is an organosilane compound having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom, and which may also have a hydrolyzable group bonded to a silicon atom.

[0029] Component (a) is an unsaturated group-containing component. An addition reaction between the unsaturated group of component (a) and the Si-H group (hydrosilyl group) of component (b) forms a network structure in the gel crosslinked product. Furthermore, if component (a) has a hydrolyzable group bonded to a silicon atom, a hydrolyzable group is introduced into component (A).

[0030] In component (a), the number of unsaturated groups can be one or more arbitrary numbers, and can be appropriately selected within the range in which a gel crosslink is formed, depending on the number of Si-H groups in component (b).

[0031] Component (a) is not particularly limited as long as it can form the network structure together with component (b), and can be component (a-1), component (a-2), or a combination of component (a-1) and component (a-2).

[0032] <(a-1) A polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom, and which may also have a hydrolyzable group bonded to a silicon atom> Component (a-1) is a polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom, and which may also have a hydrolyzable group bonded to a silicon atom.

[0033] In component (a-1), the number of unsaturated groups (monovalent groups having an aliphatic unsaturated bond attached to a silicon atom) is one or more arbitrary numbers in the molecule, preferably 2 to 100, and more preferably 2 to 50.

[0034] In component (a-1), the concentration of unsaturated groups is preferably 0.01 mmol / g to 10 mmol / g, and particularly preferably 0.05 mmol / g to 5 mmol / g. The concentration of unsaturated groups in component (a-1) is the amount of unsaturated groups per 1 g of component (a-1).

[0035] The siloxane skeleton of component (a-1) may be linear, branched, or cyclic. In this specification, a linear or branched siloxane skeleton does not include a cyclic siloxane skeleton.

[0036] Component (a-1) is typically represented by the general formula (I): (R １１ ) ａ１ (R １２ ) ｂ１ SiO （４－ａ１－ｂ１）／２ (I) (wherein, R １１ R is a monovalent group having an aliphatic unsaturated bond; １２ The molecule contains at least one alkenyl group-containing siloxane unit represented by (where a1 is a monovalent hydrocarbon group without an aliphatic unsaturated bond; a1 is an integer from 1 to 3; b1 is an integer from 0 to 2, where a1 + b1 is from 1 to 3).

[0037] R １１ It is preferable that the component is an alkenyl group, and particularly preferable that it is a vinyl group, because it is easy to synthesize and does not impair the fluidity of each component forming the gel before curing, or the heat resistance of the resulting gel. It is preferable that a1 be 1 because it is easy to synthesize. R １２ The group is preferably an alkyl group or an aryl group, more preferably a methyl group or a phenyl group, and particularly preferably a methyl group, because it is easy to synthesize and has an excellent balance of properties such as mechanical strength and fluidity before curing.

[0038] Examples of organic groups bonded to the silicon atoms of other siloxane units in component (a-1) include monovalent hydrocarbon groups that do not have aliphatic unsaturated bonds, and hydrolyzable groups. The said organic group is R １２ For similar reasons, the group is preferably an alkyl group or an aryl group, more preferably a methyl group or a phenyl group, and particularly preferably a methyl group. If the organic group is a hydrolyzable group, component (a-1) has a hydrolyzable group bonded to a silicon atom.

[0039] R １１ It may be present at either the end or in the middle of the molecular chain of component (a-1), or at both.

[0040] Component (a-1) includes a polyorganosiloxane having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom and a hydrolyzable group bonded to the silicon atom (a-1-1), and a polyorganosiloxane having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom and not having a hydrolyzable group bonded to the silicon atom (a-1-2).

[0041] ≪Component (a-1-1): A polyorganosiloxane having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and a hydrolyzable group bonded to a silicon atom≫ Component (a-1-1) is a polyorganosiloxane having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and a hydrolyzable group bonded to a silicon atom. Component (a-1-1) is a component for introducing a hydrolyzable group into component (A).

[0042] In component (a-1-1), the number of unsaturated groups is preferably 2 to 10 per molecule. If component (a-1-1) is a linear siloxane, the number of unsaturated groups in component (a-1-1) is preferably 1 or 2 per molecule. If component (a-1-1) is a cyclic siloxane, the number of unsaturated groups in component (a-1-1) is preferably 2 or 3 per molecule.

[0043] The concentration of unsaturated groups and the siloxane skeleton of component (a-1-1) are as described above for component (a-1). Component (a-1-1) is preferably a linear polyorganosiloxane or a branched polyorganosiloxane.

[0044] Furthermore, component (a-1-1) may be a polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and a side chain represented by the following formula (II) bonded to a silicon atom.

[0045] (In formula (II), L １ L represents a linear or branched alkylene group that forms a carbon chain having two or more carbon atoms between a silicon atom and an ester bond; ２R represents a linear or branched alkylene group that forms a carbon chain having three or more carbon atoms between the oxygen atom and the silicon atom of the side chain; １３ (This represents an alkyl group having 1 to 4 carbon atoms or a 2-methoxyethyl group.)

[0046] L １ Ethylene groups and 2-methylethylene groups are preferred because they are easy to synthesize and handle. ２ Trimethylene groups are preferred because they are easy to synthesize and handle. １３ From the viewpoint of reactivity, methyl and ethyl groups are preferred, with methyl groups being particularly preferred.

[0047] Furthermore, in the above case, it is preferable that the monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and the side chain are bonded to separate silicon atoms, as this facilitates synthesis. Therefore, it is preferable that the basic portion of the polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and a side chain represented by formula (II) bonded to a silicon atom forms a linear, branched, or cyclic siloxane skeleton.

[0048] Specific examples of the linear component (a-1-1) include the polyorganosiloxanes shown below. (CH ２ =CH)(CH ３ ) ２ SiO[Si(CH ３ ) ２ O] １０ Si(OCH) ３ ) ３ (CH ２ =CH)(CH ３ ) ２ SiO[Si(CH ３ ) ２ O] ２０ Si(OCH) ３ ) ３ (CH ２ =CH)(CH ３ ) ２ SiO[Si(CH ３ ) ２ O] ３０ Si(OCH) ３ ) ３ (CH２ =CH)(CH ３ ) ２ O[Si(CH ３ ) ２ O] ３０ [Si(CH ３ )(CH ２ CH ２ Si(OCH ３ ) ３ ) ２ Si(CH ２ =CH)(CH ３ )<00​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​In component (a-1-2), the concentration of unsaturated groups and the siloxane skeleton are as described above for component (a-1). Component (a-1-2) is preferably a linear polyorganosiloxane or a branched polyorganosiloxane.

[0054] Except as stated above, components (a) and (a-1) are as described above. Components (a-1-2) may be one component or a combination of two or more components.

[0055] <Preferred Embodiment of Component (a-1)> The viscosity of component (a-1) 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 at 23°C. When the viscosity of component (a-1) is within the above range, it tends to have excellent workability and superior shear resistance. Here, if component (a-1) is a combination of two or more types, the viscosity of component (a-1) refers to the viscosity of the mixed component (a-1). In this specification, viscosity is the value measured at 23°C using a rotational viscometer in accordance with JIS K 6249. When measuring viscosity, the spindle number and rotation speed are arbitrary within the range in which viscosity can be measured and can be set as appropriate.

[0056] Component (a-1) may be one component or a combination of two or more components.

[0057] <(a-2) An organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and which may also have a hydrolyzable group bonded to a silicon atom> Component (a-2) is an organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and which may also have a hydrolyzable group bonded to a silicon atom.

[0058] Organosilane compounds are silane compounds that do not have a siloxane bond (Si-O-Si). Preferably, organosilane compounds are compounds that have one silicon atom in their molecule.

[0059] In component (a-2), the number of unsaturated groups is one or more arbitrary numbers in the molecule, preferably 1 to 3.

[0060] Examples of component (a-2) include component (a-2-1), an organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and a hydrolyzable group bonded to the silicon atom, and component (a-2-2), an organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and not having a hydrolyzable group bonded to the silicon atom.

[0061] ≪(a-2-1) An organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and a hydrolyzable group bonded to a silicon atom≫ Component (a-2-1) is an organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and a hydrolyzable group bonded to a silicon atom. Component (a-2-1) is a component for introducing a hydrolyzable group into component (A).

[0062] In component (a-2-1), the number of unsaturated groups is preferably one or two in the molecule.

[0063] Component (a-2-1) may have a monovalent hydrocarbon group without an aliphatic unsaturated bond, in addition to an unsaturated group and a hydrolyzable group bonded to a silicon atom. The monovalent hydrocarbon group without an aliphatic unsaturated bond is preferably a methyl group or a phenyl group, and is particularly preferably a methyl group.

[0064] Specific examples of component (a-2-1) include alkenylalkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, methylvinyldimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and methylallyldimethoxysilane; and (meth)acryloxypropylalkoxysilanes such as 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyl(methyl)dimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-methacryloxypropyl(methyl)dimethoxysilane.

[0065] Except as stated above, components (a) and (a-2) are as described above. Component (a-2-1) may be one component or a combination of two or more components.

[0066] ≪(a-2-2) An organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and lacking a hydrolyzable group bonded to the silicon atom≫ Component (a-2-2) is an organosilane compound having a monovalent group with an aliphatic unsaturated bond bonded to a silicon atom, and lacking a hydrolyzable group bonded to the silicon atom.

[0067] In component (a-2-2), it is preferable that there be one or two unsaturated groups in the molecule.

[0068] Component (a-2-2) may have a monovalent hydrocarbon group without an aliphatic unsaturated bond, in addition to the unsaturated group. The monovalent hydrocarbon group without an aliphatic unsaturated bond is as described above for component (a-2-1).

[0069] Specific examples of component (a-2-2) include alkenyl silanes such as divinyldimethylsilane, and (meth)acryloxypropyl silanes such as 3-acryloxypropyl(trimethyl)silane.

[0070] Except as stated above, components (a) and (a-2) are as described above. Component (a-2-2) may be one component or a combination of two or more components.

[0071] Component (a-2) may be one component or a combination of two or more components.

[0072] [Component (b)] Component (b) is one or more selected from the group consisting of component (b-1) and component (b-2). Here, component (b-1) is a polyorganosiloxane having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom. Component (b-2) is an organosilane compound having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom.

[0073] Component (b) is a component containing an Si-H group (hydrosilyl group). Furthermore, component (b) having two or more Si-H groups can function as a crosslinking agent for component (a). If component (b) has a hydrolyzable group bonded to a silicon atom, the hydrolyzable group is introduced into component (A).

[0074] In component (b), the number of Si-H groups is one or more arbitrary numbers in the molecule, and can be appropriately selected within the range in which a gel crosslink is formed, depending on the number of unsaturated groups in component (a).

[0075] Component (b) is not particularly limited as long as it can form the network structure together with component (a), and can be component (b-1), component (b-2), or a combination of component (b-1) and component (b-2).

[0076] <(b-1) Polyorganosiloxane having hydrogen atoms bonded to silicon atoms and possibly having hydrolyzable groups bonded to silicon atoms> Component (b-1) is a polyorganosiloxane having hydrogen atoms bonded to silicon atoms and possibly having hydrolyzable groups bonded to silicon atoms.

[0077] In component (b-1), the number of Si-H groups in the molecule is one or more arbitrary numbers, preferably 2 to 100, and more preferably 2 to 50.

[0078] In component (b-1), the concentration of Si-H groups is preferably 0.01 mmol / g to 15 mmol / g, and particularly preferably 0.02 mmol / g to 14 mmol / g. The concentration of Si-H groups in component (b-1) is the amount of Si-H groups per 1 g of component (b-1).

[0079] The siloxane skeleton of component (b-1) can be linear, branched, or cyclic.

[0080] Component (b-1) is typically represented by general formula (III): (R １４ ) ｃ１ H ｄ１ SiO （４－ｃ１－ｄ１）／２ (III) (wherein, R １４ (where represents a monovalent hydrocarbon group without an aliphatic unsaturated bond; c1 is an integer from 0 to 2; d1 is an integer from 1 to 3, where c1 + d1 is an integer from 1 to 3) The molecule has at least one siloxane unit represented by (where c1 represents a monovalent hydrocarbon group without an aliphatic unsaturated bond; c1 is an integer from 0 to 2; d1 is an integer from 1 to 3, where c1 + d1 is an integer from 1 to 3).

[0081] R １４ It is preferable that the group is an alkyl group, and particularly preferable that it is a methyl group, because it is easy to synthesize. Also, it is preferable that d1 is 1, because it is easy to synthesize.

[0082] Examples of organic groups bonded to the silicon atoms of other siloxane units in component (b-1) include monovalent hydrocarbon groups that do not have aliphatic unsaturated bonds, and hydrolyzable groups. The said organic group is R １４ For similar reasons, it is preferable that the group be an alkyl group, and particularly preferable that it be a methyl group. If the organic group is a hydrolyzable group, component (b-1) has a hydrolyzable group bonded to a silicon atom.

[0083] From the standpoint of ease of synthesis, component (b-1) preferably has three or more siloxane units. Furthermore, from the standpoint of not volatilizing when heated to the curing temperature and having excellent fluidity, making it easy to mix 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 viewpoint of efficiently functioning as a crosslinking agent for component (a), component (b-1) preferably has three or more units represented by general formula (III) in its molecule.

[0084] The siloxane skeleton in component (b-1) may be linear, branched, or cyclic. It is preferable that the siloxane skeleton in component (b-1) be linear or cyclic. In the case of component (b-1), the Si-H group may be present at the end of the molecular chain of component (b-1), at an intermediate unit, or at both.

[0085] Component (b-1) includes component (b-1-1), a polyorganosiloxane having hydrogen atoms bonded to silicon atoms and hydrolyzable groups bonded to silicon atoms, and component (b-1-2), a polyorganosiloxane having hydrogen atoms bonded to silicon atoms and not having hydrolyzable groups bonded to silicon atoms.

[0086] ≪(b-1-1) Polyorganosiloxane having hydrogen atoms bonded to silicon atoms and hydrolyzable groups bonded to silicon atoms≫ Component (b-1-1) is a polyorganosiloxane having hydrogen atoms bonded to silicon atoms and hydrolyzable groups bonded to silicon atoms. Component (b-1-1) is a component for introducing hydrolyzable groups into component (A).

[0087] In component (b-1-1), the number of Si-H groups, the concentration of Si-H groups, and the siloxane skeleton are as described above for component (b-1). Furthermore, if the siloxane skeleton of component (b-1-1) is cyclic, it is preferable that the number of Si-H groups contained in component (b-1-1) is two or three per molecule.

[0088] Component (b-1-1) includes polyorganosiloxanes represented by the following general formula (IV).

[0089] [In the formula, R １５ R is a group having an alkoxysilyl group with 1 to 4 carbon atoms. １６ Each of these is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and lacking an aliphatic unsaturated bond, X １ is a divalent hydrocarbon group having 2 to 10 carbon atoms, and when n1 is 2 or more, X1 is the same or different, R １７ Each of these is independently a hydrogen atom, an alkoxy group, and -X. １ -R １５ R １６ The base is defined as follows: n1 is between 0 and 500, n2 is between 0 and 500, n3 is between 0 and 500, however, if n1 is 0, then at least one R １７ is an alkoxy group or -X １ -R １５ And if n2 is 0, then at least one R １７ This is a hydrogen atom.

[0090] R １５ Units including SiHR １６ The unit represented by O, SIR １６ ２ The units represented by O do not need to be arranged as shown in the general formula (IV) above; for example, R １５ Units including SiHR １６ Between the units represented by O and SIR １６ ２ A unit represented by O may exist.

[0091] R １５ R is a group having an alkoxysilyl group with 1 to 4 carbon atoms, and is a hydrolyzable functional group. １５ X is directly produced by silicon. １ It may be bonded to, but may also be bonded by linking groups such as ester bonds. １５ It is preferable that the group has a structure having two or more, particularly three, alkoxy groups. Also, from the viewpoint of ease of obtaining the raw material, R １５ It is preferable that it contains a methoxysilyl group. １５X directly through the silicon atom １ They may be bonded together, or they may be bonded together by linking groups such as ester bonds.

[0092] R １５ The following group structure is preferred.

[0093] R １５ is the base X １ It is bonded to the linear siloxane moiety of the siloxane represented by general formula (V) via group X. １ It is a divalent hydrocarbon group having 2 to 10 carbon atoms, -CH ２ CH ２ -ien-CH ２ CH ２ CH ２ -ien-CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ -ien-CH ２ CH (CH ３ ) -, -CH ２ CH (CH ３ )CH ２ Examples include alkylene groups with 2 to 10 carbon atoms, such as -. From the standpoint of ease of synthesis, group X １ ha-CH ２ CH ２ - or -CH ２ CH (CH ３ ) - is preferable.

[0094] R １６ This is a monovalent hydrocarbon group having 1 to 12 carbon atoms and not possessing an aliphatic unsaturated bond. １６ They may be the same or different. Because synthesis is easy, R １６ R is preferably an alkyl group or a hydrogen atom, and particularly preferably a methyl group or a hydrogen atom. １７ Each of these is independently a hydrogen atom, an alkoxy group, and -X. １ -R １５ , or R １６ It is a group defined as (i.e., a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond). １７This is selected appropriately according to n1 and n2.

[0095] n1 is between 0 and 500. Preferably, n1 is between 0 and 90. If n1 is 0, at least one R １７ is an alkoxy group or -X １ -R １５ Therefore, the polyorganosiloxane represented by general formula (IV) has an alkoxy group bonded to a silicon atom in its molecule.

[0096] n2 is between 0 and 500. It is preferable that n2 is between 0 and 90. If n2 is 0, at least one R １７ This is a hydrogen atom. Therefore, polyorganosiloxanes represented by general formula (IV) have hydrogen atoms bonded to silicon atoms in their molecules.

[0097] Furthermore, in general formula (IV), if both n1 and n2 are 0, then at least one R １７ is an alkoxy group or -X １ -R １５ And, at least one R １７ R is a hydrogen atom. In this case, R is a hydrogen atom in general formula (IV). １７ A silicon atom bonded to it, and an alkoxy group or -X １ -R １５ R is １７ It is preferable that the bonded silicon atom is different from the one to which it is bonded. n3 is 0 to 500. It is preferable that n3 is 0 to 90.

[0098] Furthermore, component (b-1-1) is preferably a polyorganosiloxane having a Si-H group and a side chain represented by formula (II) bonded to a silicon atom. Also, it is preferable that the Si-H group and the side chain represented by formula (II) are bonded to separate silicon atoms, as this facilitates synthesis. Therefore, the basic portion of the polyorganosiloxane having a Si-H group and a side chain represented by formula (II) preferably forms a linear, branched, or cyclic siloxane skeleton. Here, the side chain represented by formula (II) is as described above in component (a-1-1).

[0099] Specific examples of component (b-1-1) include the following polyorganosiloxanes.

[0100]

[0101] (In the formula, n4 is between 0 and 500, preferably between 0 and 90. n4 may also be between 1 and 90.)

[0102]

[0103] (In the formula, n5 is between 0 and 500, and preferably between 0 and 90.)

[0104]

[0105]

[0106] Except as stated above, components (b) and (b-1) are as described above. Component (b-1-1) may be one component or a combination of two or more components.

[0107] ≪(b-1-2) Polyorganosiloxane having hydrogen atoms bonded to silicon atoms and not having hydrolyzable groups bonded to silicon atoms≫ Component (b-1-2) is a polyorganosiloxane having hydrogen atoms bonded to silicon atoms and not having hydrolyzable groups bonded to silicon atoms.

[0108] In component (b-1-2), the number of Si-H groups, the concentration of Si-H groups, and the siloxane skeleton are as described above for component (b-1).

[0109] Except as stated above, components (b) and (b-1) are as described above. Component (b-1-2) may be one component or a combination of two or more components.

[0110] ≪Preferred Embodiment of Component (b-1)≫ The viscosity of component (b-1) is preferably 1 to 10,000 mPa·s at 23°C, and particularly preferably 1 to 1,000 mPa·s. When the viscosity of component (b-1) is within the above range, it tends to have excellent workability and superior shear resistance. The viscosity is as described above for component (a-1).

[0111] Component (b-1) may be one component or a combination of two or more components.

[0112] <(b-2) Organosilane compound having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom> Component (b-2) is an organosilane compound having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom. The organosilane compound is as described above in component (a-2). Furthermore, if component (b-2) has a hydrolyzable group bonded to a silicon atom, the hydrolyzable group is introduced in component (A).

[0113] In component (b-2), the number of Si-H groups in the molecule is one or more arbitrary numbers, preferably 1 to 3.

[0114] Examples of component (b-2) include component (b-2-1), an organosilane compound having a hydrogen atom bonded to a silicon atom and a hydrolyzable group bonded to the silicon atom, and component (b-2-2), an organosilane compound having a hydrogen atom bonded to a silicon atom and not having a hydrolyzable group bonded to the silicon atom.

[0115] ≪(b-2-1) Organosilane compound having a hydrogen atom bonded to a silicon atom and a hydrolyzable group bonded to a silicon atom≫ Component (b-2-1) is an organosilane compound having a hydrogen atom bonded to a silicon atom and a hydrolyzable group bonded to a silicon atom. Component (b-2-1) is a component for introducing a hydrolyzable group into component (A).

[0116] In component (b-2-1), the number of Si-H groups in the molecule is preferably 1 to 3, and more preferably 1 or 2.

[0117] Component (b-2-1) may have a monovalent hydrocarbon group without an aliphatic unsaturated bond, in addition to the Si-H group and the hydrolyzable group bonded to the silicon atom. The monovalent hydrocarbon group without an aliphatic unsaturated bond is as described above for component (a-2-1).

[0118] Specific examples of component (b-2-1) include alkoxysilanes such as trimethoxysilane, triethoxysilane, methyldimethoxysilane, and methyldiethoxysilane.

[0119] Except as stated above, components (b) and (b-2) are as described above. Component (b-2-1) may be one component or a combination of two or more components.

[0120] ≪(b-2-2) Organosilane compound having a hydrogen atom bonded to a silicon atom and not having a hydrolyzable group bonded to a silicon atom≫ Component (b-2-2) is an organosilane compound having a hydrogen atom bonded to a silicon atom and not having a hydrolyzable group bonded to a silicon atom.

[0121] In component (b-2-2), the number of hydrogen atoms bonded to the silicon atom is preferably 1 to 3, and more preferably 1 to 2, in the molecule.

[0122] Component (b-2-2) may have a monovalent hydrocarbon group without an aliphatic unsaturated bond in addition to the Si-H group. The monovalent hydrocarbon group without an aliphatic unsaturated bond is as described above for component (a-2-1).

[0123] Specific examples of component (b-2-2) include alkylsilanes such as trimethylsilane and triethylsilane.

[0124] Except as stated above, components (b) and (b-2) are as described above. Component (b-2-2) may be one component or a combination of two or more components.

[0125] [Regarding components (a) and (b)] Component (a) contains component (a-1), and / or component (b) contains component (b-1). That is, one or both of components (a) and (b) are components having a polyorganosiloxane skeleton. This allows for the efficient acquisition of silicone gel crosslinked products of components (a) and (b) having desired properties (e.g., penetration).

[0126] One or both of component (a) and component (b) contain a component having a hydrolyzable group bonded to a silicon atom. This allows the silicone gel crosslinked product of component (a) and component (b) to have a hydrolyzable group bonded to a silicon atom.

[0127] Possible combinations of such components (a) and (b) include the following raw material mixtures for silicone gel crosslinking (i) to (vii) (hereinafter simply referred to as "raw material mixtures"). Here, "at least contains" means that components (a) and (b) other than those mentioned may or may not be included. Raw material mixture (iii) shall not contain component (b-1-2). Also, raw material mixture (v) shall not contain component (b-1-2). The raw material mixtures may contain any components other than components (a) and (b).

[0128] (i) A raw material mixture containing at least component (a-1-1) and component (b-1-1); (ii) A raw material mixture containing at least component (a-1-1) and component (b-1-2); (iii) A raw material mixture containing at least component (a-1-2) and component (b-1-1); (iv) A raw material mixture containing at least component (a-1-2), component (b-1-1), and component (b-1-2); (v) A raw material mixture containing at least component (a-1-2) and component (b-2-1); (vi) A raw material mixture containing at least component (a-1-2), component (b-2-1), and component (b-1-2); or (vii) A raw material mixture containing at least component (a-1-2), component (a-2-1), and component (b-1-2);

[0129] In the raw material mixture, the concentration of unsaturated groups in each component (a) or the concentration of Si-H groups in each component (b) is as described above. The raw material mixture is preferably (i), (iii), or (v).

[0130] For each monovalent group having an aliphatic unsaturated bond bonded to a silicon atom in component (a), the number of hydrogen atoms bonded to a silicon atom in component (b) (hereinafter referred to as "H") （ｂ） / Vi （ａ） It is also called "H".) The amount is 0.02 to 4.（ｂ） / Vi （ａ） The amount of "H" is preferably between 0.1 and 3. （ｂ） / Vi （ａ） When the 's' value is high, the remaining SiH reacts, which tends to affect the heat resistance, especially the change in hardness.

[0131] [Method for producing component (A)] The method for producing component (A) is not particularly limited as long as it can produce the desired silicone gel crosslinked product. A specific example of a method for producing component (A) is a method that includes the steps of mixing component (a) and component (b) to obtain a raw material mixture, and crosslinking each component in the raw material mixture to obtain a silicone gel crosslinked product.

[0132] <(c) Platinum-based catalyst> The method for producing component (A) can be carried out in the presence of (c) platinum-based catalyst. Component (c) is a component that promotes the crosslinking reaction (gelation reaction) of component (A).

[0133] Component (c) includes well-known catalysts used in hydrosilylation reactions. Specific examples of component (c) include platinum compounds such as chloroplatinic acid, reaction products of chloroplatinic acid and alcohols, platinum-alcohol complexes (Lamoreau catalyst (platinum-octanol complex)), platinum-olefin complexes, platinum-vinylsiloxane complexes (Karlsted complex, platinum-1,1,3,3-tetramethyl-1,3-divinyldisiloxane complex (platinum-methylvinylsiloxane dimer complex), Ashby complex, platinum-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane complex (platinum-methylvinylsiloxane tetramer complex)), platinum-ketone complexes, and platinum-phosphine complexes.

[0134] The amount of component (c) used should be as much as is necessary for gelation and can be adjusted as appropriate according to the desired curing speed, etc. Preferably, the amount of component (c) used is in the range of 1 to 100 ppm in terms of platinum metal atoms relative to the total amount of component (A).

[0135] <(d) Reaction inhibitor> The method for producing component (A) can be carried out in the presence of (d) reaction inhibitor. Examples of component (d) include organic compounds having polar groups in their molecules, such as diallyl maleate, and organic compounds having unsaturated bonds, such as acetylene alcohols and their derivatives.

[0136] The amount of component (d) used should be within a range that does not impair the properties of component (A), but it is preferably 0.01 to 1 part by mass per 100 parts by mass of component (A-1).

[0137] In the method for producing component (A), the components can be mixed using a mixer such as a planetary mixer, kneader, or Shinagawa mixer to obtain a mixture. The crosslinking reaction can be carried out by heating the mixture at 60 to 150°C for 30 to 180 minutes.

[0138] Component (A) may be a single component or a combination of two or more components.

[0139] [(B) Thermally conductive inorganic filler] Component (B) is a thermally conductive inorganic filler. Component (B) is a component that imparts thermal conductivity to the composition.

[0140] Component (B) can be any material with good thermal conductivity. Examples of component (B) include inorganic powders such as aluminum oxide, zinc oxide, silicon oxide, silicon carbide, silicon nitride, magnesium oxide, aluminum nitride, boron nitride, and graphite, as well as metal powders such as aluminum, copper, silver, nickel, iron, and stainless steel. Component (B) typically has a functional group (e.g., a hydroxyl group) that can react with the hydrolyzable group of component (A).

[0141] The shape of component (B) is arbitrary and may be rounded, crushed, spherical, or polyhedral.

[0142] The average particle size of component (B) is arbitrary as long as it imparts the desired consistency and thermal conductivity to the composition. The average particle size of component (B) is preferably 0.01 to 500 μm, more preferably 0.01 to 300 μm, and particularly preferably 0.1 to 200 μm. When the average particle size of component (B) is 0.01 μm or larger, the desired consistency (200 to 450 at 23°C) tends to be easily obtained in the heat dissipation material. When the average particle size of component (B) is 500 μm or smaller, the thin-film coating properties of the heat dissipation material tend to improve. The average particle size can be determined, for example, using laser diffraction. Note that if component (B) has a monodisperse particle size distribution, the average particle size of component (B) and the peak diameter of the particle size distribution are synonymous.

[0143] Specific examples of component (B) based on average particle size include: (B-1) a first thermally conductive inorganic filler with an average particle size of 0.01 μm or more and less than 1 μm; (B-2) a second thermally conductive inorganic filler with an average particle size of 1 μm or more and less than 15 μm; (B-3) a third thermally conductive inorganic filler with an average particle size of 15 μm or more and 500 μm or less; and (B-4) a fourth thermally conductive inorganic filler selected from the group consisting of thermally conductive inorganic fillers with an average particle size of less than 0.01 μm and thermally conductive inorganic fillers with an average particle size exceeding 500 μm.

[0144] When component (B) contains thermally conductive inorganic fillers with different average particle sizes, the thermal conductivity of the composition tends to increase. Therefore, it is preferable that component (B) contains components (B-1), (B-2), and (B-3). In the above case, component (B) may also contain component (B-4).

[0145] Here, component (B-1) may have a monodisperse particle size distribution. In this case, the average particle diameter of component (B-1) and the peak diameter of the particle size distribution of component (B-1) are synonymous. Alternatively, component (B-1) may be a thermally conductive inorganic filler having two or more monodisperse particle size distributions. In this case, component (B-1) contained in the composition may have at least two peaks in its particle size distribution, i.e., it may have a polydisperse particle size distribution. The same applies to components (B-2), (B-3), and (B-4).

[0146] Furthermore, the composition may include, as (B-1), one or more first thermally conductive inorganic fillers having a particle size distribution peak in the range of 0.01 μm or more and less than 1 μm; as (B-2), one or more second thermally conductive inorganic fillers having a particle size distribution peak in the range of 1 μm or more and less than 15 μm; and as (B-3), one or more third thermally conductive inorganic fillers having a particle size distribution peak in the range of 15 μm or more and 500 μm or less. In addition, as (B-4), one or more fourth thermally conductive inorganic fillers selected from the group consisting of thermally conductive inorganic fillers having a particle size distribution peak in the range of less than 0.01 μm and thermally conductive inorganic fillers having a particle size distribution peak in the range where the average particle diameter exceeds 500 μm.

[0147] If component (B) contains components (B-1), (B-2), and (B-3), the content of each component is preferably as follows.

[0148] From the viewpoint of workability and thermal conductivity, the content of component (B-1) per 100 parts by mass of the total of component (B) is preferably 0.01 to 99.98 parts by mass, and preferably 1 to 99 parts by mass.

[0149] From the viewpoint of workability and thermal conductivity, the content of component (B-2) per 100 parts by mass of the total of component (B) is preferably 0.01 to 99.98 parts by mass, and more preferably 1 to 99 parts by mass.

[0150] From the viewpoint of workability and thermal conductivity, the content of component (B-3) per 100 parts by mass of the total of component (B) is preferably 0.01 to 99.98 parts by mass, and more preferably 1 to 99 parts by mass.

[0151] The total content of components (B-1), (B-2), and (B-3) is preferably 80.00 to 100 parts by mass, more preferably 90.00 to 100 parts by mass, and particularly preferably 98.00 to 100 parts by mass, per 100 parts by mass of the total of component (B). The remainder is component (B-4). Furthermore, component (B) may consist only of components (B-1), (B-2), and (B-3).

[0152] Regarding components (B-1), (B-2), and (B-3), they are the same as described above for component (B), except for the average particle size.

[0153] Component (B-1) is preferably zinc oxide and / or alumina. Furthermore, the shape of component (B-1) is preferably rounded, crushed, spherical, or polyhedral.

[0154] Component (B-2) is preferably one or more selected from the group consisting of alumina, aluminum nitride, silicon carbide, boron nitride, silicon nitride, aluminum hydroxide, magnesium oxide, and zinc oxide, and is particularly preferably alumina and / or aluminum nitride. The shape of component (B-2) is preferably rounded, crushed, spherical, or polyhedral.

[0155] Component (B-3) is preferably one or more selected from the group consisting of alumina, aluminum nitride, silicon carbide, boron nitride, silicon nitride, aluminum hydroxide, magnesium oxide, and zinc oxide, and is particularly preferably alumina and / or aluminum nitride. The shape of component (B-3) is preferably rounded, crushed, spherical, or polyhedral.

[0156] Component (B-4) can be appropriately selected from the components and shapes described above in components (B-1) to (B-3).

[0157] [Other Components] The thermally conductive polyorganosiloxane composition may optionally contain other components, as long as they do not impair the effects of the present invention. Other components include components (C) and (D) described later, as well as further component (E).

[0158] [Component (C)] Component (C) is (C-1) a polyorganosiloxane having a viscosity of 1 to 10,000 mPa·s at 23°C and containing hydrolyzable groups bonded to silicon atoms, and / or (C-2) R １ ａ R ２ ｂ Si ( OR ３ ) （４－ａ－ｂ） (In the formula, each R １Each R is an alkyl group having 1 to 3 carbon atoms, and each R ２ These are, independently, alkyl groups having 6 to 12 carbon atoms, and each R ３ (a) is an alkylalkoxysilane represented by (a) independently being an alkyl group having 1 to 3 carbon atoms, where a is 0 or 1 to 3, and b is 0 or 1 to 3, provided that a + b is 1 to 3). Component (C) is a surface treatment agent for component (B) contained in the composition. Component (C) is also called a wetter for component (B). When the composition contains component (C), the packing density of component (B) can be increased. This tends to increase the thermal conductivity of the composition. The hydrolyzable groups are as described above. The viscosity is as described above for component (a-1).

[0159] <(C-1) A polyorganosiloxane having a viscosity of 1 to 10,000 mPa·s at 23°C and containing hydrolyzable groups bonded to silicon atoms> Component (C-1) is a polyorganosiloxane having a viscosity of 1 to 10,000 mPa·s at 23°C and containing hydrolyzable groups bonded to silicon atoms. Since the viscosity of component (C-1) at 23°C is 1 to 10,000 mPa·s, it is not a gel crosslinked product like component (A). The viscosity of component (C-1) is preferably 1 to 1,000 mPa·s at 23°C, and particularly preferably 1 to 500 mPa·s. When the viscosity of component (C-1) is within the above range, the filler's filling ability and workability tend to improve.

[0160] The siloxane skeleton in component (C-1) may be cyclic or linear. Component (C-1) may or may not have hydrogen atoms bonded to the silicon atom. Component (C-1) may or may not have a monovalent group having an aliphatic unsaturated bond bonded to the silicon atom. Therefore, as long as the viscosity at 23°C is 1 to 10,000 mPa·s, component (C-1) may be a component included in the aforementioned components (a-1-1) and (b-1-1).

[0161] A specific example of a cyclic component (C-1) is the general formula (V): [In the formula, R ２１ R is a group having an alkoxysilyl group with 1 to 4 carbon atoms. ２２ The general formula (VI) is as follows: (In the formula, R ２４ Each of these is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and not possessing an aliphatic unsaturated bond, Y １ R ２４ A linear organosiloxy group represented by (a group selected from the group consisting of monovalent groups having an aliphatic unsaturated bond, where d is an integer from 2 to 60), X １１ and X １２ Each is independently a divalent hydrocarbon group having 2 to 10 carbon atoms, a2 and b2 are independently integers of 1 or more, c2 is an integer of 0 or more, a + b + c is an integer of 4 or more, R ２３ Examples of siloxane compounds are represented by [each independently being a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom that does not have an aliphatic unsaturated bond].

[0162] In the cyclic component (C-1), R ２１ Units including R ２２ Units including SiR ２３ ２ The units represented by O do not need to be arranged as shown in the general formula (V) above; for example, R ２１ Units including R ２２ Between the units containing SiR ２３ ２ A unit represented by O may exist.

[0163] Siloxane compounds having a cyclic structure represented by general formula (V) can incorporate many hydrolyzable groups into the cyclic structure, and because these groups are spatially concentrated, the processing efficiency of component (B) is increased, which is thought to enable higher packing. In addition, because the siloxane compound itself has high heat resistance, it can impart high heat resistance to thermally conductive polyorganosiloxane compositions. Furthermore, siloxane compounds represented by general formula (V) have the advantage of being easily obtained by addition reactions, for example, with a cyclic siloxane containing a hydrogen group, a siloxane having a vinyl group at one end, and a silane compound containing a vinyl group and a hydrolyzable group.

[0164] R ２１ R is a group having an alkoxysilyl group with 1 to 4 carbon atoms. ２１ R in general formula (IV) １５ As stated above.

[0165] R ２２ This is a linear organosiloxy group represented by general formula (VI). In general formula (VI), the number of d2 is an integer from 2 to 60. The number of d2 being between 2 and 60 enhances the effect on fluidity, enables high formulations, and suppresses the viscosity of the siloxane compound itself. ２４ Each of these is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms and lacking an aliphatic unsaturated bond, and is linear or branched in shape. １－１２ Examples include alkyl groups and aryl groups such as phenyl and naphthyl. Furthermore, the hydrocarbon group may be substituted with halogens such as chlorine, fluorine, and bromine; perfluoroalkyl groups such as trifluoromethyl groups are examples of such groups. Because of their ease of synthesis, R ２４ It is preferable that it is a methyl group. １ R ２４The group is selected from the group consisting of a monovalent group having an aliphatic unsaturated bond. The monovalent group having an aliphatic unsaturated bond is preferably an alkenyl group, preferably an alkenyl group having 2 to 10 carbon atoms, and more preferably an alkenyl group having 2 to 6 carbon atoms. Furthermore, the alkenyl group is preferably having a double bond at its terminal end because it facilitates the hardening reaction. Y is easy to synthesize. １ It is preferable that the group is a methyl group or a vinyl group.

[0166] R ２１ is the base X １１ via R ２２ is the base X １２ It is bonded to the cyclic siloxane moiety of the siloxane represented by general formula (V) via the group X. １１ or X １２ It is a divalent hydrocarbon group having 2 to 10 carbon atoms, -CH ２ CH ２ -ien-CH ２ CH ２ CH ２ -ien-CH ２ CH ２ CH ２ CH ２ CH ２ CH ２ -ien-CH ２ CH (CH ３ ) -, -CH ２ CH (CH ３ )CH ２ Examples include alkylene groups with 2 to 10 carbon atoms, such as -. From the standpoint of ease of synthesis, group X １１ or X １２ ha-CH ２ CH ２ - or -CH ２ CH (CH ３ ) - is preferable.

[0167] R ２３ Each of these is independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom. ２３ They may be the same or different. Because synthesis is easy, R ２３ It is preferable that this is a methyl group or a hydrogen atom.

[0168] a2 is an integer greater than or equal to 1, preferably 1. b2 is an integer greater than or equal to 1, preferably 1 or 2. c2 is an integer greater than or equal to 0, preferably 0 to 2. The sum of a2 + b2 + c2 is an integer greater than or equal to 4, but is preferably 4 because it is easy to compose.

[0169] More specific examples of the cyclic component (C-1), in addition to those described in the examples, include the siloxane compound shown in the following structural formula.

[0170]

[0171] A specific example of a linear component (C-1) is a siloxane compound shown in the following structural formula. (In the formula, n11 is between 5 and 90.)

[0172] (In the formula, n12 is between 5 and 90.)

[0173] Component (C-1) may be one component or a combination of two or more components.

[0174] <(C-2)R １ ａ R ２ ｂ Si ( OR ３ ) （４－ａ－ｂ） The alkylalkoxysilane shown is component (C-2), R １ ａ R ２ ｂ Si ( OR ３ ) （４－ａ－ｂ） This is an alkylalkoxysilane represented by the formula. Here, in the above formula, each R １ Each R is an alkyl group having 1 to 3 carbon atoms, and each R ２ These are, independently, alkyl groups having 6 to 12 carbon atoms, and each R ３ A is independently an alkyl group having 1 to 3 carbon atoms, where a is 0 or 1 to 3, and b is 0 or 1 to 3, provided that a+b is 1 to 3. In component (C-2), if a+b is 1 or 2, it is preferable that a is 0 or 1 and b is 0 or 1.

[0175] Specific examples of component (C-2) include methyltrimethoxysilane, hexyltrimethoxysilane, heptyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, dodecylmethyldimethoxysilane, dodecyltriethoxysilane, tetradecyltrimethoxysilane, octadecyltrimethoxysilane, octadecylmethyldimethoxysilane, octadecyltriethoxysilane, and nonadecyltrimethoxysilane.

[0176] Component (C-2) may be one component or a combination of two or more components.

[0177] [Component (D)] Component (D) is a polyorganosiloxane that does not have functional groups that react with components (A) and (B). When a composition contains component (D), the viscosity of the composition tends to be controllable. Furthermore, when a composition contains component (D), it can accommodate a wide range of handling requirements and desired physical properties.

[0178] Component (D) may include siloxane resins that do not have curable functional groups, such as polydimethylsiloxane. Examples of siloxane resins that are component (D) include resins obtained from combinations of the M, D, T, and / or Q units that do not have hydrolyzable groups.

[0179] Component (D) is given by the following general formula (VI): R ３１ ３ Si-O-(SiR ３１ ２ O) ｖ -SiR ３１ ３ (VI) (wherein, R ３１ Preferably, the material is a siloxane resin represented by (where is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, and v is a number that gives a viscosity of 1 mPa·s to 10,000 mPa·s at 23°C).

[0180] The viscosity of component (D) is preferably 1 mPa·s to 10,000 mPa·s at 23°C, and particularly preferably 1 mPa·s to 1,000 mPa·s. When the viscosity of component (D) is within the above range, viscosity adjustment can be performed more efficiently. Here, the viscosity is as described above for component (a-1).

[0181] Component (D) may be a single component or a combination of two or more components.

[0182] [Component (E)] Examples of component (E) include organic solvents, adhesion promoters, inorganic pigments, organic pigments, thixotropy promoters, viscosity modifiers, UV inhibitors, antifungal agents, heat resistance improvers, flame retardants, etc. Component (E) can be appropriately selected from components that are normally added to thermally conductive polyorganosiloxane compositions. Component (E) may be a single component or a combination of two or more components.

[0183] <Content of each component> In the composition, the content of each component is preferably as follows.

[0184] The total content of component (A) and component (B) is preferably 50.0 to 100 parts by mass, more preferably 60 to 99 parts by mass, and particularly preferably 70 to 98 parts by mass, based on 100 parts by mass of the total composition.

[0185] The content of component (B) is preferably 500 to 10,000 parts by mass, more preferably 1,000 to 9,000 parts by mass, and particularly preferably 2,000 to 8,000 parts by mass, per 100 parts by mass of component (A).

[0186] From the viewpoint of filler-filling properties, the content of component (C) is preferably 10 to 500 parts by mass, and particularly preferably 20 to 400 parts by mass, per 100 parts by mass of component (A).

[0187] From the viewpoint of workability, the content of component (D) is preferably 1 to 500 parts by mass, and particularly preferably 1 to 300 parts by mass, per 100 parts by mass of component (A).

[0188] The content of component (E) is not particularly limited as long as it does not impair the intended use of the composition, but it is preferably 1 to 500 parts by mass, and particularly preferably 1 to 100 parts by mass, per 100 parts by mass of component (A).

[0189] [Method for producing a thermally conductive polyorganosiloxane composition] A thermally conductive polyorganosiloxane composition can be produced by uniformly kneading components (A) and (B) with optional components (C) to (E) using a universal kneader or other mixing means.

[0190] [Uses of Thermally Conductive Polyorganosiloxane Compositions] Because thermally conductive polyorganosiloxane compositions have thermal conductivity, they can be used as heat dissipation materials. Thermally conductive polyorganosiloxane compositions can be used, for example, as heat dissipation parts in electronic components.

[0191] [Articles containing thermally conductive polyorganosiloxane compositions] Articles containing thermally conductive polyorganosiloxane compositions are preferably articles comprising a substrate and the composition. Examples of articles comprising a substrate and the composition include electronic devices and electronic components such as integrated circuit elements.

[0192] The method for manufacturing the article is not particularly limited. Preferably, the method for manufacturing the article includes the steps of preparing a component and a composition including a base material, and applying the composition to the surface of the base material.

[0193] In addition to metals, suitable substrates include polyester resins such as epoxy resin, polyethylene terephthalate, and polybutylene terephthalate (PBT) resin, engineering plastics such as polycarbonate resin, acrylic resin, polyimide resin, phenolic resin, polyamide resin, polyphenylene sulfide (PPS) resin, and modified polyphenylene ether (PPE) resin; and glass. If necessary, the walls of the voids may be treated with a primer according to conventional methods. The shape and thickness of the substrate are not particularly limited.

[0194] Methods for applying the thermally conductive polyorganosiloxane composition include dropping, injection, casting, extrusion from a container, coating such as bar coating and roll coating, screen printing, dipping, brush coating, spraying, and dispensing. The composition may be applied evenly and uniformly to the surface of the part, or it may be applied unevenly or partially, such as in linear, stripe, or dot patterns. The application thickness of the composition is preferably 0.01 to 10 mm, and particularly preferably 0.05 to 5 mm.

[0195] [Characteristics of Thermally Conductive Polyorganosiloxane Compositions] A thermally conductive polyorganosiloxane composition preferably has a thermal conductivity of 1.0 (W / (m·K)) or higher, more preferably 3.5 (W / (m·K)) or higher, and particularly preferably 4.5 (W / (m·K)) or higher, measured by the hot disk method at 23°C. When the thermal conductivity is 1.0 (W / (m·K)) or higher, the thermal conduction performance is often sufficient, and the applications tend to be less limited. The upper limit of the thermal conductivity is arbitrary and can be appropriately set depending on the manner in which the thermally conductive polyorganosiloxane composition is used.

[0196] The thermally conductive polyorganosiloxane composition exhibits excellent shear resistance. In this specification, "excellent shear resistance" means that the displacement distance after the heat cycle test described below is 0 mm or more and less than 3 mm. Here, "displacement distance" means the distance the thermally conductive polyorganosiloxane composition has shifted (moved) from its position at the start of the test to its position after the test. The displacement distance after the heat cycle test described below is preferably 0 mm or more and 1 mm or less, and particularly preferably 0 mm. That is, it is particularly preferable that the thermally conductive polyorganosiloxane composition does not exhibit any displacement after the shear resistance test. The heat cycle test can be performed, for example, using a thermal shock tester. The heat cycle test corresponds to the "shear resistance test" in the examples.

[0197] (Heat Cycle Test) A 2 mm spacer is placed between two glass slides (76 mm long, 26 mm wide, 1 mm thick) and a thermally conductive polyorganosiloxane composition is sandwiched in a circular shape with a diameter of 1 cm to obtain a test specimen. This test specimen is placed at a 90-degree angle to the ground (i.e., perpendicular), and a heat cycle of -40°C for 30 minutes and 125°C for 30 minutes, totaling 60 minutes per cycle, is performed for 250 cycles. After 250 cycles, the distance the thermally conductive polyorganosiloxane composition has shifted from its original position is defined as the displacement distance.

[0198] The present invention will be described in further detail below with reference to examples and comparative examples. In these examples, parts represent parts by mass. Viscosity is expressed as the viscosity at 23°C. The present invention is not limited to these examples.

[0199] <Ingredients Used> Ingredient (A): Gel 1 to Gel 9 were manufactured by "Gel Synthesis". The ingredients used in the synthesis of the gels are as follows.

[0200] (a) Unsaturated group-containing component: Polyorganosiloxane (vinyl polymer) represented by the following formula

[0201] (b) Si-H group-containing components: (1) Polyorganosiloxane (SiH) represented by the following formula

[0202] (2) Polyorganosiloxane (alkoxy group-containing SiH 1) represented by the following formula (3) Polyorganosiloxane (alkoxy group-containing SiH2) represented by the following formula (4) Polyorganosiloxane (alkoxy group-containing SiH3) represented by the following formula

[0203] (c) Platinum catalyst: Platinum-vinyl tetramer complex (d) Reaction inhibitor: Ethynylcyclohexanol represented by the following formula

[0204] Components (B): B-1-1: Zinc oxide, average particle size 0.1 μm, rounded; B-1-2: Alumina, average particle size 0.6 μm, rounded; B-1-3: Alumina, average particle size 0.4 μm, crushed; B-1-4: Alumina, average particle size 0.8 μm, rounded; B-2-1: Alumina, average particle size 7 μm, spherical; B-2-2: Aluminum nitride, average particle size 5 μm, rounded; B-3-1: Alumina, average particle size 75 μm, spherical; B-3-2: Aluminum nitride, average particle size 70 μm, rounded; B-3-3: Aluminum nitride, average particle size 170 μm, rounded

[0205] Component (C): C-1: Wetter 1: Siloxane compound represented by the following formula (viscosity: 47 mPa·s; where n is approximately 21).

[0206] C-2: Wetter 2: Siloxane compound represented below (viscosity: 70 mPa·s; where n is approximately 31).

[0207] C-3: Wetter 3: Siloxane compound represented below (viscosity: 190 mPa·s; where n is approximately 71). Ingredients (D): D-1: Dimethyl silicone oil (polydimethylsiloxane, viscosity 1 mPa·s)

[0208] (Viscosity) Viscosity was measured at 23°C using a rotational viscometer in accordance with JIS K 6249. The spindle number and rotation speed were set as appropriate when measuring viscosity.

[0209] (Gel Synthesis) In the mass ratios shown in Table 1, (a) an unsaturated group-containing component and (b) a Si-H group-containing component, (c) a platinum-based catalyst, and (d) a reaction inhibitor were mixed and heated at 150°C for 2 hours to obtain a gel (component (A)). In Table 1, "Total H / Vi" is the total number of hydrogen atoms bonded to silicon atoms in components (b-1), (b-2), and (b-3) per monovalent unsaturated hydrocarbon group bonded to silicon atoms in component (a). Also in Table 1, "Amount of Trimethoxysilyl Groups" is the amount of trimethoxysilyl groups per 1 g of component (A), and was determined by the amount charged. In Table 1, "Amount of Trimethoxysilyl Groups" corresponds to the "Concentration of Silicon Atoms Bonded with Hydrolyzable Groups" in component (A).

[0210] <Penetration Depth> The obtained gel was placed in a 23 mm diameter container and degassed by centrifugal force. Next, using an automatic microconcentrator (Maytec Co., Ltd., model number: 25Z-9EA), a 1 / 4 cone was inserted for 5 seconds, and the penetration depth of the gel was read.

[0211] (Preparation of thermally conductive polyorganosiloxane composition) The components were mixed at 2,000 rpm for 30 seconds using a rotation-and-revolution type mixer (manufactured by Thinky Co., Ltd., model number: ARE-310) with the compositions shown in Tables 2 and 3. The resulting mixture was heated in an oven at 150°C for 4 hours to obtain a thermally conductive polyorganosiloxane composition.

[0212] <Thermal Conductivity> The thermal conductivity of the thermally conductive polyorganosiloxane composition was measured at 23°C using a hot disk method thermophysical property measurement device (manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0213] <Shearing Test (Vertical Shearing Test)> A 2 mm spacer was placed between two glass slides (76 mm long, 26 mm wide, 1 mm thick) and a thermally conductive polyorganosiloxane composition was sandwiched in a circular shape with a diameter of 1 cm to obtain a test specimen. This test specimen was placed in a thermal shock tester (manufactured by ESPEC Corporation, model number: TSA-73ES-W) set to alternately cycle between -40°C and 125°C (30 minutes each), with the specimen tilted 90 degrees to the ground (i.e., vertical), and a 250-cycle test was performed. After 250 cycles, the distance of displacement of the thermally conductive polyorganosiloxane composition from its original position was measured, and the "distance of displacement" was determined. This "distance of displacement" was then recorded in the "Shearing Test" column in the table.

[0214] The results are summarized in Tables 1 to 3.

[0215]

[0216]

[0217]

[0218] Tables 2 and 3 show that the compositions of the examples exhibited excellent shear resistance. Examples 1 to 14 are compositions containing any of gels 1 to 8 and 10 to 12. Gels 1 to 8 and 10 to 12 are silicone gel crosslinks having hydrolyzable groups bonded to silicon atoms (i.e., component (A)). Examples 1 to 14 demonstrate that excellent shear resistance was maintained even when the amount of trimethoxysisilyl groups (silicon atoms to which hydrolyzable groups are bonded) in component (A) was changed. Examples 1 to 14 also demonstrated excellent shear resistance even when the siloxane skeleton in component (b-1) was changed. Furthermore, Examples 1 to 14 demonstrated excellent shear resistance even when the type of component (B) was changed. Compared to Example 14, which used alumina, Examples 12 to 13, which used aluminum nitride as component (B), had higher thermal conductivity and better heat dissipation.

[0219] Comparative Example 1 is a composition containing gel 9. Gel 9 is a silicone gel crosslinked product that does not have hydrolyzable groups bonded to silicon atoms. The composition of Comparative Example 1 showed significant shear after the heat cycle test and had poor shear resistance.

Claims

1. A thermally conductive polyorganosiloxane composition comprising (A) a silicone gel crosslinked material having hydrolyzable groups bonded to silicon atoms, and (B) a thermally conductive inorganic filler.

2. Component (A) is a silicone gel crosslinked product comprising: (a) (a-1) a polyorganosiloxane having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, and (a-2) an organosilane compound having a monovalent group having an aliphatic unsaturated bond bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom; and (b) (b-1) a polyorganosiloxane having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, and (b-2) an organosilane compound having a hydrogen atom bonded to a silicon atom and possibly having a hydrolyzable group bonded to a silicon atom, wherein component (a) contains component (a-1) and / or component (b) contains component (b-1). The thermally conductive polyorganosiloxane composition according to claim 1, wherein one or both of component (a) and component (b) contain a component having a hydrolyzable group bonded to a silicon atom, and the amount of component (b) is such that for each monovalent group having an aliphatic unsaturated bond bonded to a silicon atom in component (a), the number of hydrogen atoms bonded to a silicon atom in component (b) is 0.02 to 4.

3. The thermally conductive polyorganosiloxane composition according to claim 1, wherein the concentration of silicon atoms to which hydrolyzable groups are attached in component (A) is 0.01 mmol / g to 20 mmol / g.

4. The thermally conductive polyorganosiloxane composition according to claim 1, wherein the penetration of component (A) (ASTMD1403, 1 / 4 cone) is 10 to 200.

5. The thermally conductive polyorganosiloxane composition according to claim 1, comprising 500 to 10,000 parts by mass of component (B) per 100 parts by mass of component (A).

6. Component (B) is as follows: (B-1) a first thermally conductive inorganic filler with an average particle size of 0.01 μm or more and less than 1 μm, (B-2) a second thermally conductive inorganic filler with an average particle size of 1 μm or more and less than 15 μm, and The thermally conductive polyorganosiloxane composition according to claim 1, comprising (B-3) a third thermally conductive inorganic filler having an average particle diameter of 15 μm or more and 500 μm or less, wherein the content of component (B-1) is 0.01 to 99.98 parts by mass, the content of component (B-2) is 0.01 to 99.98 parts by mass, and the content of component (B-3) is 0.01 to 99.98 parts by mass, and the total content of components (B-1), (B-2), and (B-3) is 80.00 to 100 parts by mass.

7. The thermally conductive polyorganosiloxane composition according to claim 6, wherein the shape of component (B-1) is rounded, crushed, spherical, or polyhedral.

8. The thermally conductive polyorganosiloxane composition according to claim 6, wherein the shape of component (B-2) is rounded, crushed, spherical, or polyhedral.

9. The thermally conductive polyorganosiloxane composition according to claim 7, wherein the shape of component (B-2) is rounded, crushed, spherical, or polyhedral.

10. The thermally conductive polyorganosiloxane composition according to claim 6, wherein the shape of component (B-3) is rounded, crushed, spherical, or polyhedral.

11. The thermally conductive polyorganosiloxane composition according to claim 7, wherein the shape of component (B-3) is rounded, crushed, spherical, or polyhedral.

12. The thermally conductive polyorganosiloxane composition according to claim 8, wherein the shape of component (B-3) is rounded, crushed, spherical, or polyhedral.

13. The thermally conductive polyorganosiloxane composition according to claim 9, wherein the shape of component (B-3) is rounded, crushed, spherical, or polyhedral.

14. Further, (C) a polyorganosiloxane having a viscosity at 23° C. of 1 to 10,000 mPa·s and containing a hydrolyzable group bonded to a silicon atom, and / or R １ ａ R ２ ｂ Si(OR ３ ) （４－ａ－ｂ） (In the formula, each R １ is independently an alkyl group having 1 to 3 carbon atoms, each R ２ is independently an alkyl group having 6 to 12 carbon atoms, each R ３ is independently an alkyl group having 1 to 3 carbon atoms, a is 0 or 1 to 3, b is 0 or 1 to 3, provided that a + b is 1 to 3) The thermally conductive polyorganosiloxane composition according to claim 1, comprising an alkylalkoxysilane represented by 15. The thermally conductive polyorganosiloxane composition according to claim 1, further comprising (D) a polyorganosiloxane that does not have functional groups that react with component (A) and component (B).

16. The thermally conductive polyorganosiloxane composition according to claim 1, wherein the displacement distance after the heat cycle test described below is 0 mm or more and 1 mm or less. (Heat cycle test) A test specimen is obtained by sandwiching the thermally conductive polyorganosiloxane composition in a circular shape with a diameter of 1 cm between two slide glass plates (76 mm long, 26 mm wide, 1 mm thick) with a 2 mm spacer. This test specimen is placed at a 90-degree angle to the ground, and a heat cycle of -40°C for 30 minutes and 125°C for 30 minutes, totaling 60 minutes per cycle, is performed for 250 cycles. After 250 cycles, the distance the thermally conductive polyorganosiloxane composition has shifted from its original position is defined as the displacement distance.

17. An electronic component comprising the thermally conductive polyorganosiloxane composition according to any one of claims 1 to 16.

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