Condensation-curable thermally conductive silicone composition

Abstract

To provide a condensation-curable thermally conductive silicone composition that offers superior coating applicability, undergoes moisture curing at room temperature, and yields a cured product that is flexible, exhibits high thermal conductivity, and shows excellent pump-out resistance.SOLUTION: In a condensation-curable thermally conductive silicone composition having a viscosity that allows dispenser discharge at the time of coating and yielding a flexible cured product with high thermal conductivity, by blending a predetermined amount of an organic catalyst having a guanidine group and a silicone polymer having both terminals capped with alkoxysilyl groups, flexibility in the cured product of the condensation-curable thermally conductive silicone composition is maintained while achieving improved pump-out resistance during a heat cycle test.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a condensation-curable, thermally conductive silicone composition that has excellent application workability, cures at room temperature, and gives a cured product that is flexible, has high thermal conductivity, and exhibits excellent pump-out resistance. [Background technology]

[0002] It is widely known that electronic components such as LSIs and IC chips generate heat during use, resulting in a decline in performance. Various heat dissipation technologies have been developed to address this issue. For example, a known method involves placing a cooling component, such as a heat sink, near a heat-generating component and closely contacting the two to promote efficient heat transfer to the cooling component, thereby cooling the cooling component and thereby efficiently dissipating heat from the heat-generating component. In this case, if there is a gap between the heat-generating component and the cooling component, the presence of air with low thermal conductivity can result in inefficient heat transfer, preventing the temperature of the heat-generating component from dropping sufficiently. To prevent this phenomenon, heat-dissipating materials, such as heat-dissipating sheets and heat-dissipating greases, that have high thermal conductivity and conform to the surface of the components are used to prevent air from entering between the heat-generating component and the cooling component (see Japanese Patent Application Laid-Open Nos. 11-246885, 11-246884, and 2004-130646: Patent Documents 1 to 3). Among these, heat-dissipating grease exhibits high performance in terms of thermal resistance due to its flexibility and ability to be used in a thin package.

[0003] Since the heating part and the cooling member repeat heating and cooling, it is known that the member repeats thermal contraction. As a result, the separation of the oil component and the thermally conductive filler in the thermally conductive silicone composition is promoted. In addition, a phenomenon such as pump-out occurs in which the thermally conductive silicone composition is extruded from between the heating part and the cooling member. As a result, the thermal resistance increases and the heating part cannot be cooled efficiently. In order to prevent such a phenomenon, a method of adding a thickener to increase the viscosity of the thermally conductive silicone composition has been proposed (Japanese Patent Application Laid-Open No. 2004-091743 (Patent Document 4)). However, such a thermally conductive silicone composition has a problem that the viscosity becomes very high and it is difficult to apply.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above circumstances, and provides a condensation-curing type thermally conductive silicone composition that has a viscosity that can be discharged by a dispenser during application, cures with moisture at room temperature, is flexible, has high thermal conductivity, and gives a cured product excellent in pump-out resistance.

Means for Solving the Problems

[0006] As a result of extensive research into achieving the above-mentioned object, the present inventors discovered that in a condensation-curable thermally conductive silicone composition that has a viscosity that allows it to be dispensed with a dispenser when applied and that gives a flexible, highly thermally conductive cured product, by incorporating a certain amount of an organic catalyst having a guanidine group and a silicone polymer that is end-capped at both ends with alkoxysilyl groups, the flexibility of the cured product of the condensation-curable thermally conductive silicone composition is maintained while improving its resistance to pump-out during a heat cycle test, which led to the completion of the present invention.

[0007] Accordingly, the present invention provides the following condensation-curable thermally conductive silicone composition. 1. (A) 1 to 50 parts by mass of an organopolysiloxane represented by the following general formula (1) having a viscosity of 50 to 50,000 mPa s at 23°C as measured with a rotational viscometer: HO-(SiR 1 2O) k -H (1) (In the formula, R 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and k is an integer of 20 or greater. (B) an organopolysiloxane represented by the following general formula (2): 50 to 99 parts by mass, (However, the total amount of components (A) and (B) is 100 parts by mass.) [ka] (In the formula, R 2 are each independently an unsubstituted or substituted monovalent hydrocarbon group, and R 3 are independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group, n is an integer of 2 to 100, and a is an integer of 1 to 3. (C) 0.1 to 20 parts by mass of a diorganopolysiloxane having hydrolyzable silyl groups at both molecular chain terminals, which is represented by the following general formula (3) and has a viscosity of 10 to 10,000 mPa s at 23°C as measured with a rotational viscometer: [ka] [In the formula, R 4 are each independently a group selected from alkyl groups having 1 to 10 carbon atoms and alkoxyalkyl groups having 2 to 10 carbon atoms. 5 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms. b is an integer from 1 to 3. m is a number that gives the diorganopolysiloxane a viscosity of 10 to 10,000 mPa s at 23°C. Each Y is independently an oxygen atom, an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a group represented by the following formula: [ka] (In the formula, R 5 is as defined above, and Z is an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms. (D) 1 to 30 parts by mass of at least one silane compound other than components (B) and (C) which is represented by the following general formula (4) and has three or more hydrolyzable groups bonded to silicon atoms in one molecule, a partial hydrolyzate thereof, and a partial hydrolyzed condensate thereof: R 6 c Six 4-c (4) (In the formula, R 6 is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and X is independently a hydrolyzable group. c is 0 or 1. (E) 0.1 to 5 parts by mass of a curing catalyst other than components (B), (C), and (D), which is at least one selected from the group consisting of non-silicon organic compounds, hydrolyzable organosilane compounds, and partial hydrolysis condensates thereof, each having at least one guanidine skeleton represented by the following general formula (5) in one molecule: [ka] (In the formula, R 7 are each independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group. (F) Thermally conductive filler with a thermal conductivity of 10 W / (m·K) or more: 100 to 2,000 parts by mass as an essential component, and which gives a cured product that, after standing for 7 days in an environment of 23±2°C and 50±5% RH, has a Shore OO hardness at 23°C of 10 to 80 and a thermal conductivity of 1.0 W / (m·K) or greater. 2. 1. The condensation-curable thermally conductive silicone composition according to 1, further comprising (G) 0.01 to 30 parts by mass, per 100 parts by mass of the combined total of components (A) and (B), of a silane compound and / or a partial hydrolysis condensate thereof, the silane compound having a functional group selected from the group consisting of an amino group, an epoxy group, a mercapto group, an acryloyl group, and a methacryloyl group, bonded to a silicon atom via a carbon atom, and the silane compound having a hydrolyzable group bonded to a silicon atom. 3. 3. The condensation-curable thermally conductive silicone composition according to 1 or 2, which has a viscosity of 10 to 500 Pa·s as measured using a capillary rheometer at 23°C and a shear rate of 20 / sec. 4. 4. The condensation-curable thermally conductive silicone composition according to any one of 1 to 3, wherein component (B) has a viscosity of 5 to 10,000 mPa·s at 23°C as measured using a rotational viscometer. 5. 5. The condensation-curable thermally conductive silicone composition according to any one of 1 to 4, which gives a cured product that does not pump out after the heat cycle test described below. (heat cycle test) A 10mm square silicon wafer piece is placed on a 50mm long x 70mm wide aluminum substrate, and 0.2ml of condensation-curable thermally conductive silicone composition is applied to the silicon wafer. A 50mm long x 70mm wide glass plate is then placed on the condensation-curable thermally conductive silicone composition, and the condensation-curable thermally conductive silicone composition is pressed between the glass plate and the silicon wafer piece to a thickness of 100µm. The composition is then left to stand for 24 hours at 23°C and 50%RH to cure. A heat cycle of -40°C x 30 minutes, 125°C x 30 minutes, for a total of 60 minutes, is then performed 1000 times. [Effects of the Invention]

[0008] The condensation-curable thermally conductive silicone composition of the present invention has a viscosity that allows it to be dispensed with a dispenser when applied, and it cures in the presence of moisture at room temperature to give a cured product (silicone rubber) that is flexible, has excellent pump-out resistance, and exhibits high thermal conductivity, making it suitable as a heat-dissipating material. DETAILED DESCRIPTION OF THE INVENTION

[0009] The condensation-curable thermally conductive silicone composition of the present invention contains the following essential components (A) to (F), and preferably also contains the following component (G). It is characterized by the fact that it gives a cured product that, after standing for 7 days at 23°C at 23±2°C and 50±5% RH, has a Shore OO hardness of 10 to 80 and a thermal conductivity of 1.0 W / (m·K) or higher. Here, room temperature refers to 23°C±15°C, preferably 20 to 25°C. Furthermore, pump-out resistance refers to the degree to which pump-out (the phenomenon in which the cured product in the coated area is extruded from between the heat-generating part and the cooling member due to repeated heating and cooling) is suppressed in the mounted area when the composition is mounted in the gap between the heat-generating part and the cooling member, which repeatedly heats and cools electronic components. The present invention will be described in detail below.

[0010] [Component (A): Organopolysiloxane] The organopolysiloxane of component (A) is represented by the following general formula (1). HO-(SiR 1 2O) k -H (1) (In the formula, R 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and k is an integer of 20 or greater.

[0011] As shown in general formula (1) above, component (A) is a linear diorganopolysiloxane whose main chain consists of repeating diorganosiloxane units and whose molecular chain is terminated at both ends with silicon-bonded hydroxyl groups (silanol groups) and whose viscosity at 23°C measured with a rotational viscometer is 50 to 50,000 mPa·s, and which serves as the main component (base polymer) of the condensation-curable thermally conductive silicone composition of the present invention. Furthermore, linear diorganopolysiloxanes have a linear siloxane bond chain structure consisting of SiO as the main chain, but the molecular chain may also be partially branched, such as by side chain monovalent hydrocarbon groups.

[0012] In general formula (1), R 1 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, and examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, and 2-ethylhexyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, and hexenyl; aryl groups such as phenyl and tolyl; and aralkyl groups such as benzyl and phenylethyl. Alternatively, examples include groups in which the hydrogen atoms of these hydrocarbon groups are partially substituted with halogen atoms such as fluorine, chlorine, and bromine, such as a trifluoropropyl group. 1 The unsubstituted or substituted monovalent hydrocarbon group of R is preferably one that does not contain an aliphatic unsaturated bond, and specifically, an alkyl group such as a methyl group, or an aryl group such as a phenyl group is preferred, with a methyl group being particularly preferred. 1 may be the same group or different groups.

[0013] In the general formula (1), the difunctional diorganosiloxane unit ((SiR 1 2O 2 / 2)) (or the degree of polymerization), k is an integer of 20 or more, preferably an integer of 50 to 1,000, more preferably an integer of 100 to 800, and particularly preferably an integer of 200 to 700. If k is less than 20, the resulting cured product will be hard and have reduced stress relaxation performance (flexibility), whereas if k exceeds 1,000, the viscosity of the composition will be high, which may reduce coating workability.

[0014] The viscosity of the organopolysiloxane of component (A) at 23°C is in the range of 50 to 50,000 mPa·s, preferably 300 to 30,000 mPa·s, and more preferably 500 to 20,000 mPa·s. If the viscosity at 23°C is less than 50 mPa·s, the resulting cured product will be hard and its stress relaxation performance (flexibility) will be reduced. If the viscosity exceeds 50,000 mPa·s, the viscosity of the condensation-curable thermally conductive silicone composition will be high, reducing application workability. In the present invention, the viscosities of component (A) and components (B) and (C), described below, can be measured using a rotational viscometer (e.g., BL, BH, BS, or cone-plate type) in accordance with the method specified in JIS Z8803.

[0015] In the present invention, the degree of polymerization (or molecular weight) can be determined, for example, as the polystyrene-equivalent number-average degree of polymerization (or number-average molecular weight) determined by gel permeation chromatography (GPC) analysis using toluene, tetrahydrofuran (THF), or the like as a developing solvent. The organopolysiloxane of component (A) may be a single type, or two or more types may be used in combination.

[0016] If the amount of component (A) is less than 1 part by mass, the composition will not cure, and if the amount is more than 50 parts by mass, the resulting cured product will be too hard, based on a total of 100 parts by mass of components (A) and (B). Therefore, component (A) is used in the range of 1 to 50 parts by mass, preferably 2 to 40 parts by mass, and more preferably 3 to 30 parts by mass.

[0017] [Component (B): Organopolysiloxane having a hydrolyzable group at one end] Component (B) is an organopolysiloxane represented by the following general formula (2): Component (B) plays an important role in imparting appropriate hardness (flexibility) to the resulting cured product. [ka] (In the formula, R 2 are each independently an unsubstituted or substituted monovalent hydrocarbon group, and R 3 are independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group, n is an integer of 2 to 100, and a is an integer of 1 to 3.

[0018] In general formula (2), R 2 are each independently an unsubstituted or substituted monovalent hydrocarbon group having preferably 1 to 10 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3 carbon atoms. Examples of such groups include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, halogenated alkyl groups, and cyanoalkyl groups. Examples of linear alkyl groups include methyl groups, ethyl groups, propyl groups, hexyl groups, and octyl groups. Examples of branched alkyl groups include isopropyl groups, isobutyl groups, tert-butyl groups, and 2-ethylhexyl groups. Examples of cyclic alkyl groups include cyclopentyl groups and cyclohexyl groups. Examples of alkenyl groups include vinyl groups and allyl groups. Examples of aryl groups include phenyl groups and tolyl groups. Examples of aralkyl groups include 2-phenylethyl groups and 2-methyl-2-phenylethyl groups. Examples of halogenated alkyl groups include 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl, and 2-(heptadecafluorooctyl)ethyl. Examples of cyanoalkyl groups include cyanoethyl. R 2 is preferably a methyl group, a phenyl group, or a vinyl group.

[0019] In general formula (2), R 3are independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. Examples of the alkyl group include the above R 2 Examples of the alkoxyalkyl group include those having 2 to 10 carbon atoms, such as a methoxyethyl group and a methoxypropyl group. Examples of the alkenyl group include those having 2 to 10 carbon atoms, such as the above-mentioned R 2 Examples of the acyl group include those having 2 to 10 carbon atoms, such as an acetyl group and an octanoyl group. 3 As the alkyl group, an alkyl group is preferable, and a methyl group or an ethyl group is particularly preferable.

[0020] In general formula (2), n is an integer from 2 to 100, preferably an integer from 5 to 80. If n is less than 2, the resulting cured product of the condensation-curable thermally conductive silicone composition is more likely to exhibit oil bleeding and dripping. If n is greater than 100, the viscosity of the resulting condensation-curable thermally conductive silicone composition will be too high, making it difficult to apply. a is an integer of 1 to 3, and is preferably 3.

[0021] The viscosity of component (B) at 23°C is preferably 5 to 10,000 mPa·s, and more preferably 5 to 5,000 mPa·s.

[0022] Specific examples of suitable components (B) include the following: [ka] (In the formula, Me is a methyl group.) The component (B) may be used alone or in combination of two or more.

[0023] If the amount of this (B) component is less than 50 parts by mass, based on 100 parts by mass of the total of the (A) and (B) components, the composition will become hard after curing and a flexible cured product will not be obtained. If the amount is more than 99 parts by mass, the composition will not cure. Therefore, the (B) component is used in the range of 50 to 99 parts by mass, preferably 60 to 98 parts by mass, and more preferably 70 to 97 parts by mass.

[0024] [Component (C): Organopolysiloxane having hydrolyzable silyl groups at both molecular chain terminals] Component (C) is a compound represented by the following general formula (3), and adding an appropriate amount of it can impart pump-out resistance to the resulting cured product of the condensation-curable thermally conductive silicone composition. [ka] [In the formula, R 4 are each independently a group selected from alkyl groups having 1 to 10 carbon atoms and alkoxyalkyl groups having 2 to 10 carbon atoms. 5 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms. b is an integer from 1 to 3. m is a number that gives the diorganopolysiloxane a viscosity of 10 to 10,000 mPa s at 23°C. Each Y is independently an oxygen atom, an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a group represented by the following formula: [ka] (In the formula, R 5 is as defined above, and Z is an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms.

[0025] In the above formula (3), R 4are each independently selected from alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, hexyl, and octyl; and alkoxyalkyl groups having 2 to 10 carbon atoms, such as methoxymethyl, methoxyethyl, and ethoxymethyl. A methyl group or an ethyl group is preferred. R 5 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group include organic groups bonded to silicon atoms other than the above-mentioned hydroxyl group and hydrolyzable silyl group, and among these, a methyl group is preferred. b is an integer of 1 to 3, preferably 2 or 3. m is a number that provides a viscosity of the diorganopolysiloxane at 23°C of 10 to 10,000 mPa·s, preferably 50 to 8,000 mPa·s, more preferably 100 to 5,000 mPa·s, and particularly preferably 200 to 2,000 mPa·s, and is, for example, an integer of 1 to 500, preferably an integer of 50 to 450, more preferably an integer of 80 to 400, and particularly preferably 100 to 260. This repetition number (m) can be determined, for example, as the polystyrene-equivalent number average degree of polymerization (or number average molecular weight) in gel permeation chromatography (GPC) analysis using toluene or the like as a developing solvent.

[0026] In the above formula (3), each Y is independently an oxygen atom, an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 6 carbon atoms, or a group represented by the following formula: [ka] (In the formula, R 5 is as defined above, and Z is an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms.

[0027] Here, examples of the divalent hydrocarbon groups represented by Y and Z include alkylene groups such as methylene, ethylene, propylene, tetramethylene, hexamethylene, octamethylene, decamethylene, and 2-methylpropylene, arylene groups such as phenylene, groups in which these alkylene groups are bonded to arylene groups, and groups in which some or all of the hydrogen atoms bonded to carbon atoms of these groups have been substituted with halogen atoms or cyano groups. The divalent hydrocarbon group may be linear or branched, but is preferably a linear alkylene group such as methylene, ethylene, propylene, butylene, or hexylene, with ethylene being particularly preferred. It is particularly preferred that Y is an oxygen atom or an ethylene group.

[0028] The amount of component (C) added is 0.1 to 20 parts by mass, preferably 0.1 to 15 parts by mass, particularly preferably 0.5 to 10 parts by mass, and particularly preferably 1 to 8 parts by mass, based on 100 parts by mass of the total of components (A) and (B). If the amount of component (C) is too small, the cured product may have insufficient pump-out resistance, while if it is too large, the cured product may have too high hardness (reduced flexibility).

[0029] [Component (D): Hydrolyzable organosilane compounds, their partial hydrolyzates, and their partial hydrolyzed condensates] Component (D) is a silane compound other than components (B) and (C) that has three or more silicon-bonded hydrolyzable groups per molecule, or a partial hydrolyzate or partial hydrolyzed condensate thereof (i.e., a siloxane oligomer having three or more residual hydrolyzable groups per molecule), and acts as a crosslinker for the composition of the present invention. The silane compound is represented by the following general formula (4): R 6 c Six 4-c (4) (In the formula, R 6 is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and X is independently a hydrolyzable group. c is 0 or 1, preferably 1.

[0030] In general formula (4), examples of the hydrolyzable group X include ketoxime groups, alkoxy groups, acyloxy groups, and alkenyloxy groups. Specific examples include ketoxime groups having 3 to 8 carbon atoms, such as dimethylketoxime, methylethylketoxime, and methylisobutylketoxime; alkoxy groups having 1 to 4 carbon atoms, particularly 1 or 2 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, and tert-butoxy; acyloxy groups having 2 to 4 carbon atoms, such as acetoxy and propionoxy; and alkenyloxy groups having 2 to 5 carbon atoms, such as vinyloxy, allyloxy, propenoxy, isopropenoxy, and (cyclopent-1-en-1-yl)oxy. X may be the same group or different groups.

[0031] In addition, in the general formula (4), the remaining group R bonded to the silicon atom other than the hydrolyzable group 6 is not particularly limited as long as it is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and specific examples include unsubstituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, such as alkyl groups such as methyl, ethyl, propyl, and butyl, alkenyl groups such as vinyl, and aryl groups such as phenyl, as well as halogen-substituted monovalent hydrocarbon groups such as chloromethyl and trifluoropropyl, in which some of the hydrogen atoms bonded to carbon atoms of the unsubstituted monovalent hydrocarbon group have been substituted with halogen atoms such as fluorine, chlorine, and bromine. Among these, unsubstituted monovalent hydrocarbon groups are preferred, and methyl, ethyl, vinyl, and phenyl are more preferred.

[0032] Specific examples of such component (D) include ketoxime silanes such as tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutylketoxime)silane, and vinyltris(methylethylketoxime)silane; alkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane; and methyltriacetoxysilane. Examples of the silane include acyloxysilanes such as acetoxysilanes, such as vinyltriacetoxysilane and phenyltriacetoxysilane; isopropenoxysilanes, such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane and phenyltriisopropenoxysilane; alkenyloxysilanes such as silyl enol ethers, such as methyltris[(cyclopent-1-en-1-yl)oxy]silane, vinyltris[(cyclopent-1-en-1-yl)oxy]silane and phenyltris[(cyclopent-1-en-1-yl)oxy]silane; and partial hydrolysates and partial hydrolyzed condensates of these silanes, with alkenyloxysilanes being more preferred. These may be used alone or in combination of two or more.

[0033] The amount of this component (D) to be blended is 1 to 30 parts by mass, preferably 2 to 28 parts by mass, and more preferably 5 to 25 parts by mass, because if it is less than 1 part by mass, the composition will not cure, and if it is more than 30 parts by mass, the time until curing will be longer, relative to 100 parts by mass of the total of components (A) and (B).

[0034] [(E) component] Component (E) is at least one compound selected from the group consisting of non-silicon organic compounds, hydrolyzable organosilane compounds, and partial hydrolysis condensates thereof, all of which have at least one guanidine skeleton per molecule and are other than components (B), (C), and (D) (hereinafter, the "hydrolyzable organosilane compounds and partial hydrolysis condensates thereof" in component (E) are collectively referred to as organosilicon compounds). Component (E) acts as a curing catalyst (catalyst component) in the condensation-curable thermally conductive silicone composition of the present invention, and not only does it impart good curability to the composition of the present invention, but in combination with component (C), it also improves pump-out resistance while maintaining flexibility in the resulting cured product.

[0035] Here, having at least one guanidine skeleton in one molecule means that the compound contains a structure in which one nitrogen atom is bonded to one carbon atom via a double bond and two nitrogen atoms are bonded to one carbon atom via single bonds, and this structure is represented by the following general formula (5). [ka] (In the formula, R 7 are each independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group, preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group or an ethyl group, a methylol group, or a cyano group, more preferably a hydrogen atom or a methyl group.

[0036] The non-silicon organic compound and hydrolyzable organosilane compound in component (E) are represented, for example, by the following general formula (5'). [ka] (In the formula, R 7 is the same as above, and R 8is a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, a cyano group, or an alkoxysilane residue, preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group or an ethyl group, a methylol group, a cyano group, or an alkoxysilane residue, more preferably a hydrogen atom, a methyl group, or an alkoxysilane residue. 7 or R 8 When is a hydrogen atom, it may form a salt with an inorganic acid by hydrogen bonding.

[0037] In the above formulas (5) and (5'), R 7 and R 8 Examples of unsubstituted or substituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and octadecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and α- and β-naphthyl; aralkyl groups such as benzyl, 2-phenylethyl, and 3-phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as F, Cl, or Br, or with cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl.

[0038] In addition, in the above formula (5'), R 8 The alkoxysilane residue is represented by the following formula: -A-Si(OR') 3-d R'' d (In the formula, A is a divalent hydrocarbon group having 1 to 8 carbon atoms, R' and R'' are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and d is 0, 1, or 2.)

[0039] In the above formula, A is a divalent hydrocarbon group having 1 to 8 carbon atoms, preferably a divalent hydrocarbon group having 2 to 4 carbon atoms, and is —(CH2) p An alkylene group of - (p represents 1 to 8) is preferred. R' and R'' each independently represent an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; vinyl, allyl, propenyl, isopropenyl, butenyl, pentenyl, and hexenyl; Examples include alkenyl groups; aryl groups such as phenyl, tolyl, xylyl, and α- and β-naphthyl; aralkyl groups such as benzyl, 2-phenylethyl, and 3-phenylpropyl; groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as F, Cl, and Br, or with cyano groups, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and 2-cyanoethyl; and alkyl groups in which some of the hydrogen atoms of these groups have been substituted with lower alkoxy groups such as methoxy and ethoxy, such as methoxymethyl, methoxyethyl, ethoxymethyl, and ethoxyethyl. Among these, lower alkyl groups having 1 to 4 carbon atoms, such as methyl and ethyl, are preferred.

[0040] Specific examples of non-silicon organic compounds having at least one guanidine skeleton within the molecule of component (E) include inorganic guanidines such as guanidine hydrochloride, guanidine carbonate, guanidine nitrate, guanidine sulfate, and guanidine phosphate, and organic guanidines such as aminoguanidine, 1,1,3,3-tetramethylguanidine, n-dodecylguanidine, methylolguanidine, dimethylolguanidine, 1-phenylguanidine, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, triphenylguanidine, and 1-benzyl-2,3-dimethylcyanoguanidine. Specific examples of organic silicon compounds include alkoxysilanes such as 1,1,3,3-tetramethyl-2-[3-(trimethoxysilyl)propyl]guanidine (also known as tetramethylguanidylpropyltrimethoxysilane) and N-[bis(dimethylamino)methylene]-N'-[3-(triethoxysilyl)propyl]urea, and their hydrolysis condensates (siloxanes). Among these, it is preferable to use organic guanidines, alkoxysilanes, and their hydrolysis condensates, and it is particularly preferable to use alkoxysilanes such as 1,1,3,3-tetramethyl-2-[3-(trimethoxysilyl)propyl]guanidine and N-[bis(dimethylamino)methylene]-N'-[3-(triethoxysilyl)propyl]urea, and their hydrolysis condensates.

[0041] The guanidine skeleton-containing non-silicon organic compound and / or organosilicon compound of the curing catalyst (catalyst component), component (E), may each be one type, or two or more types may be used in combination. Component (E) (the non-silicon organic compound and / or organosilicon compound having at least one guanidine skeleton per molecule) is used in an amount of 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass, and more preferably 0.25 to 3 parts by mass, per 100 parts by mass of the total of components (A) and (B). If the amount is too small, the curing properties of the composition may deteriorate, and if the amount is too large, odor and storage stability may deteriorate.

[0042] [Component (F): Thermally conductive filler] If the thermal conductivity of the thermally conductive filler for component (F) is less than 10 W / (m·K), the thermal conductivity of the condensation-curable thermally conductive silicone composition itself will be low, so a filler with a thermal conductivity of 10 W / (m·K) or higher, preferably 15 W / (m·K) or higher, is used. Examples of such thermally conductive fillers include aluminum powder, copper powder, silver powder, nickel powder, gold powder, alumina powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, boron nitride powder, silicon nitride powder, diamond powder, and carbon powder. However, any filler with a thermal conductivity of 10 W / (m·K) or higher will do, and they may be used alone or in combination of two or more types.

[0043] If the average particle size of the thermally conductive filler is less than 0.1 μm, the viscosity may be high and the composition may be difficult to work with. If it is more than 200 μm, the uniformity of the condensation-curable thermally conductive silicone composition may be poor. Therefore, the range of 0.1 to 200 μm is preferable, and the range of 0.1 to 150 μm is more preferable. Furthermore, the shape of the filler may be any shape, including amorphous and spherical. The average particle size can be determined, for example, as the weight average value (or median diameter) using laser diffraction method.

[0044] The amount of component (F) blended is in the range of 100 to 2,000 parts by mass, preferably 500 to 1,800 parts by mass, based on 100 parts by mass of the total of components (A) and (B), since less than 100 parts by mass will not achieve the desired thermal conductivity, and more than 2,000 parts by mass will result in a composition that is difficult to apply.The content of component (F) in the total composition is preferably in the range of 55 to 95% by mass, more preferably 60 to 94% by mass.

[0045] [Component (G): Silane coupling agent and / or partial hydrolysis condensate thereof] The condensation-curable thermally conductive silicone composition of the present invention may further contain, as component (G), a silane compound and / or a partial hydrolysis condensate thereof, which has a functional group selected from the group consisting of amino, epoxy, mercapto, acryloyl, and methacryloyl groups bonded to a silicon atom via a carbon atom and also has a hydrolyzable group bonded to a silicon atom. This component serves to improve adhesion between the composition of the present invention and the surface (substrate) to which it is applied.

[0046] The silane compound and its partial hydrolysis condensate preferably have 1 to 3, more preferably 2 or 3, hydrolyzable groups. When the silane compound and its partial hydrolysis condensate contain two or more of the above functional groups, they may be bonded to the silicon atom via different carbon atoms, or may be bonded to the silicon atom via the same carbon atom. Examples of the hydrolyzable group include the same hydrolyzable group X in general formula (4) of component (D), and among these, alkoxy groups are preferred.

[0047] Specific examples of the silane compound include amino group-containing silanes such as 3-aminopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 2-aminoethylaminomethyldimethoxymethylsilane, and 2-aminoethylaminomethyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxyethyltrimethoxysilane; Examples include epoxy group-containing silanes such as dimethoxymethylsilane, mercapto group-containing silanes such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, and γ-mercaptopropylmethyldiethoxysilane, and (meth)acryloyl group (acryloyl group or methacryloyl group)-containing silanes such as methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane, acryloxypropyltrimethoxysilane, and acryloxypropyltriethoxysilane. Component (G) is not limited to a single type, and may be used as a mixture of two or more types.

[0048] When the above component (G) is blended, the blending amount is preferably in the range of 0.01 to 30 parts by mass, more preferably in the range of 0.1 to 20 parts by mass, per 100 parts by mass of the total of components (A) and (B). By keeping the blending amount within this range, the adhesion between the composition of the present invention and the coated surface (substrate) is improved.

[0049] In addition to the components (A) through (G) described above, the condensation-curable thermally conductive silicone composition of the present invention may contain commonly known additives, provided they do not impair the objectives of the present invention. Examples of such additives include polyethers as thixotropy improvers, silicone oils and isoparaffins as plasticizers, and, if necessary, colorants such as pigments, dyes, and fluorescent brighteners, as well as bioactive additives such as fungicides, antibacterial agents, and marine life repellents. Furthermore, surface modifiers such as phenylsilicone oil, alkyl-modified silicone oil, and fluorosilicone oil for improving reworkability, silicone resins for improving strength, and organic liquids incompatible with silicones, as well as solvents such as toluene, xylene, volatile solvents, cyclohexane, methylcyclohexane, and low-boiling-point isoparaffins, may also be added.

[0050] The condensation-curable thermally conductive silicone composition of the present invention can be prepared by uniformly mixing the above components using a known method. The viscosity of the resulting condensation-curable thermally conductive silicone composition, measured using a capillary rheometer at 23°C and a shear rate of 20 / sec, is preferably 10 to 500 Pa·s, and more preferably 30 to 400 Pa·s. Having a viscosity within this range improves the ease of application of the condensation-curable thermally conductive silicone composition; in other words, it allows the condensation-curable thermally conductive silicone composition to be easily dispensed from a dispenser (application gun) when applied to an object.

[0051] The condensation-curable thermally conductive silicone composition of the present invention, after being left for 7 days (after curing) in an environment of 23±2°C and 50±5% RH, has a hardness of 10 to 80 Shore 00 at 23°C, preferably 30 to 75. If the hardness is less than 10, the composition after curing will be too soft, and pump-out may occur due to deterioration over time, making it impossible to achieve adequate heat dissipation performance. If the hardness is more than 80, stress relaxation performance (flexibility) will be poor, and thermal distortion may cause defects in electronic devices or heat dissipation materials. Hardness can be measured according to the method specified in ISO 7619-1.

[0052] Furthermore, in the condensation-curable thermally conductive silicone composition of the present invention, the above hardness range can be achieved by mixing the organopolysiloxane of component (A) and the organopolysiloxane having a hydrolyzable group at one end of component (B) in amounts ranging from 1 to 50 parts by mass of component (A) and from 50 to 99 parts by mass of component (B) to make a total of 100 parts by mass, and then adding the required amounts of thermally conductive filler and crosslinker to form a composition. Furthermore, in order to improve pump-out resistance, it is effective to add 0.1 to 20 parts by mass of component (C) and 0.1 to 5 parts by mass of component (E).

[0053] Furthermore, the condensation-curable thermally conductive silicone composition of the present invention has a thermal conductivity at 23°C after curing of at least 1.0 W / (m·K), and preferably at least 3.0 W / (m·K). Thermal conductivity can be measured using the hot disc method in accordance with ISO 22007-2. Furthermore, the condensation-curable thermally conductive silicone composition of the present invention can achieve the above thermal conductivity by adding component (F), a thermally conductive filler with a thermal conductivity of at least 10 W / (m·K), to the composition in an amount of 100 to 2,000 parts by mass per 100 parts by mass of the combined components (A) and (B).

[0054] The condensation-curable heat-conductive silicone composition of the present invention preferably provides a cured product that does not pump out after the heat cycle test described below. (heat cycle test) A 10mm square silicon wafer piece is placed on a 50mm long x 70mm wide aluminum substrate, and 0.2ml of condensation-curable heat-conductive silicone composition is applied to the silicon wafer. A 50mm long x 70mm wide glass plate is then placed on the condensation-curable heat-conductive silicone composition, and the condensation-curable heat-conductive silicone composition is pressed between the glass plate and the silicon wafer piece to a thickness of 100µm. The composition is then left to stand for 24 hours at 23°C and 50%RH to cure. A heat cycle of -40°C x 30 minutes, 125°C x 30 minutes, for a total of 60 minutes, is then performed 1,000 times.

[0055] As mentioned above, the condensation-curable thermally conductive silicone composition obtained in this manner has a viscosity before curing that allows it to be dispensed with a dispenser during application, and the cured product obtained after curing has moderate flexibility, making it excellent for reworkability and eliminating the risk of placing excessive stress on electronic devices. Furthermore, the cured product has high thermal conductivity and good pump-out resistance, making it suitable for use in a wide range of fields that require heat dissipation and heat resistance, such as the electrical and electronics and transportation fields. It is particularly suitable for use in electronic components, automotive parts, and heat-dissipating materials. [Example]

[0056] The present invention will be described in further detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Specific examples will be presented to further clarify the advantages of the present invention. In the following formula, Me represents a methyl group. The viscosities of the following components (A), (B), and (C) are values ​​measured at 23°C using a rotational viscometer (BII type viscometer BHII, manufactured by Toki Sangyo Co., Ltd.) in accordance with the method specified in JIS Z 8803, and the average particle size of the following component (E) is a value measured using a laser diffraction particle size analyzer (product name Mastersizer 3000, manufactured by Malvern Panalytical).

[0057] First, the following components were prepared. Component (A) A-1: Dimethylpolysiloxane (k = 390 in formula (1)) with a viscosity of 5,000 mPa·s at 23°C and both ends capped with hydroxyl groups A-2: Dimethylpolysiloxane (k = 610 in formula (1)) with a viscosity of 20,000 mPa·s at 23°C and both ends capped with hydroxyl groups

[0058] (B) Component Organopolysiloxane represented by the following formula: B-1 (Viscosity at 23°C: 25 mPa·s): [ka] B-2 (Viscosity at 23°C: 28 mPa·s): [ka]

[0059] (C) Component C-1: Dimethylpolysiloxane (m = 180, b = 3, R in formula (3)) having a viscosity of 600 mPa·s at 23°C and having both ends of the molecular chain capped with trimethoxysilylethylene groups 4 and R 5 is a methyl group and Y is an ethylene group) C-2: Dimethylpolysiloxane (m = 260, b = 2, R in formula (3)) having a viscosity of 900 mPa s at 23°C and both ends of the molecular chain capped with methyldimethoxysilyloxy groups 4 and R 5 is a methyl group and Y is an oxygen atom)

[0060] (D) Component D-1: Phenyltriisopropenoxysilane D-2: Vinyltris[(cyclopent-1-en-1-yl)oxy]silane

[0061] (E) Component E-1: Tetramethylguanidylpropyltrimethoxysilane E-2: N-[bis(dimethylamino)methylene]-N'-[3-(triethoxysilyl)propyl]urea E-3 (for comparison): Dioctyl tin dilaurate

[0062] (F) Component F-1: Aluminum powder with an average particle size of 40 μm (thermal conductivity: 230 W / (m·K)) F-2: Alumina powder with an average particle size of 40 μm (thermal conductivity: 29 W / (m·K))

[0063] (G) Component G-1: 3-aminopropyltriethoxysilane

[0064] [Examples 1 to 5 and Comparative Examples 1 to 3] Condensation-curable thermally conductive silicone compositions of the examples and comparative examples were obtained by mixing components (A) to (G) in the amounts shown in Table 1 as follows. Components (A), (B), (C), and (F) were charged into a mixer stirrer (5XDMV-R, Dalton Co., Ltd.) in the amounts shown in Table 1, and heated and degassed and mixed at 170°C for 3 hours. After cooling to room temperature, components (D) and (E) were added, and the mixture was degassed and mixed at room temperature until uniform. If necessary, component (G) was added, and the mixture was degassed and mixed at room temperature until uniform. The viscosity of the condensation-curable thermally conductive silicone composition thus obtained, as well as the hardness, thermal conductivity, and pump-out resistance of the cured product, were evaluated using the methods described below. Each evaluation was performed at 23°C. The results are shown in Table 1.

[0065] [Viscosity Evaluation] The viscosity is measured at 23°C using a capillary rheometer (Malvern, RH2000) at a shear rate of 20 / sec.

[0066] [Hardness evaluation] The condensation-curable thermally conductive silicone composition was cut into a 2.0 mm sheet and left to cure at 23±2°C / 50±5% RH for 7 days, after which the Shore 00 hardness was measured according to the method specified in ISO 7619-1.

[0067] [Thermal conductivity evaluation] The condensation-curable thermally conductive silicone composition was cut into a 6.0 mm sheet and left to cure at 23±2°C / 50±5% RH for 7 days, after which the thermal conductivity was measured using a TPA-501 hot disc thermal property measuring device manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0068] [Pump-out resistance evaluation] A 10mm square silicon wafer piece was placed on a 50mm long, 70mm wide aluminum substrate, and 0.2ml of condensation curable heat conductive silicone composition was applied to the silicon wafer.Then, a 50mm long, 70mm wide glass plate was placed on the applied condensation curable heat conductive silicone composition, and the condensation curable heat conductive silicone composition was crushed between the glass plate and the silicon wafer piece to a thickness of 100μm.Then, the glass plate and the silicon wafer piece were fixed with clips, and the condensation curable heat conductive silicone composition was left to stand for 24 hours in an environment of 23℃ and 50%RH to cure.Then, 1000 cycles of heat cycles were carried out (heat cycle test), with one cycle consisting of -40℃ × 30 minutes, 125℃ × 30 minutes, a total of 60 minutes.Then, the presence or absence of the condensation curable heat conductive silicone composition protruding from between the glass plate and the silicon wafer piece was visually observed as the presence or absence of pump-out.If there was no pump-out (no protrusion of the composition), it was judged as ○, and if there was pump-out (protrusion of the composition), it was judged as ×.

[0069] [Table 1]

[0070] The above results show that the condensation-curable thermally conductive silicone compositions of the Examples have low viscosity and maintain soft physical properties at Shore 00 hardness after curing, high thermal conductivity, and good pump-out resistance. On the other hand, the condensation-curable thermally conductive silicone compositions of Comparative Examples 1 and 3 have low viscosity, but the cured product has poor pump-out resistance, and Comparative Example 3 also has high hardness after curing. Furthermore, in Comparative Example 2, the composition did not undergo phase inversion, i.e., did not become a paste, and the physical properties could not be measured, so evaluation was discontinued. This demonstrates that the condensation-curable thermally conductive silicone composition of the present invention can produce a cured product that has a low viscosity that can be dispensed using a dispenser, is flexible, has high thermal conductivity, and exhibits excellent pump-out resistance.

Claims

1. (A) 1 to 50 parts by mass of an organopolysiloxane represented by the following general formula (1) having a viscosity of 50 to 50,000 mPa s at 23°C as measured with a rotational viscometer: HO-(SiR 1 2 O) k -+ (1) (In the formula, R 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and k is an integer of 20 or greater. (B) 50 to 99 parts by mass of an organopolysiloxane represented by the following general formula (2): (However, the total amount of components (A) and (B) is 100 parts by mass.) 【Chemistry 1】 (In the formula, R 2 are each independently an unsubstituted or substituted monovalent hydrocarbon group, R 3 are independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group, n is an integer of 2 to 100, and a is an integer of 1 to 3. (C) 0.1 to 20 parts by mass of a diorganopolysiloxane having hydrolyzable silyl groups at both molecular chain terminals, which is represented by the following general formula (3) and has a viscosity of 10 to 10,000 mPa s at 23°C as measured with a rotational viscometer: 【Chemistry 2】 [In the formula, R 4 are each independently a group selected from alkyl groups having 1 to 10 carbon atoms and alkoxyalkyl groups having 2 to 10 carbon atoms. 5 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms. b is an integer of 1 to 3. m is a number that gives the diorganopolysiloxane a viscosity of 10 to 10,000 mPa·s at 23°C. Each Y is independently an oxygen atom, an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms, or a group represented by the following formula: 【Transformation 3】 (In the formula, R 5 is as defined above, and Z is an unsubstituted or substituted divalent hydrocarbon group having 1 to 20 carbon atoms. (D) 1 to 30 parts by mass of at least one silane compound other than components (B) and (C), which is represented by the following general formula (4) and has three or more hydrolyzable groups bonded to silicon atoms per molecule, a partial hydrolyzate thereof, and a partial hydrolyzed condensate thereof: R 6 c SiX 4-c (4) (In the formula, R 6 is an unsubstituted or halogen-substituted monovalent hydrocarbon group, and X is independently a hydrolyzable group. c is 0 or 1. (E) 0.1 to 5 parts by mass of a curing catalyst other than components (B), (C), and (D), which is at least one selected from the group consisting of non-silicon organic compounds, hydrolyzable organosilane compounds, and partial hydrolysis condensates thereof, each having at least one guanidine skeleton represented by the following general formula (5) in one molecule, and 【Chemistry 4】 (In the formula, R 7 are each independently a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, a methylol group, or a cyano group. (F) Thermally conductive filler having a thermal conductivity of 10 W / (m K) or more: 100 to 2,000 parts by mass as an essential component, and which gives a cured product that, after being left for 7 days in an environment of 23±2°C and 50±5% RH, has a Shore OO hardness at 23°C of 10 to 80 and a thermal conductivity of 1.0 W / (m·K) or higher.

2. The condensation-curable thermally conductive silicone composition according to claim 1, further comprising (G) 0.01 to 30 parts by mass, per 100 parts by mass of the total of components (A) and (B), of a silane compound and / or a partial hydrolysis condensate thereof, the silane compound having a functional group selected from the group consisting of an amino group, an epoxy group, a mercapto group, an acryloyl group, and a methacryloyl group, bonded to a silicon atom via a carbon atom, and having a hydrolyzable group bonded to a silicon atom.

3. 2. The condensation-curable thermally conductive silicone composition according to claim 1, which has a viscosity of 10 to 500 Pa·s as measured using a capillary rheometer at 23° C. and a shear rate of 20 / sec.

4. 2. The condensation-curable thermally conductive silicone composition according to claim 1, wherein component (B) has a viscosity of 5 to 10,000 mPa·s at 23° C. as measured using a rotational viscometer.

5. 2. The condensation-curable thermally conductive silicone composition of claim 1, which provides a cured product that does not pump out after the following heat cycle test. (Heat cycle test) A 10 mm square silicon wafer piece is placed on a 50 mm long, 70 mm wide aluminum substrate, and 0.2 ml of a condensation-curable heat-conductive silicone composition is applied to the silicon wafer. A 50 mm long, 70 mm wide glass plate is then placed on the condensation-curable heat-conductive silicone composition, and the condensation-curable heat-conductive silicone composition is pressed and fixed to a thickness of 100 μm between the glass plate and the silicon wafer piece. The composition is then left to stand for 24 hours in an environment of 23 ° C and 50% RH to cure. A heat cycle of -40 ° C x 30 minutes, 125 ° C x 30 minutes, a total of 60 minutes per cycle, is then performed 1000 times.

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