ORGANOPOLYSILOXANE, PROCESS FOR PRODUCING SAME, AND THERMALLY CONDUCTIVE SILICONE COMPOSITION

Abstract

Provided are: an organopolysiloxane represented by the general formula (wherein R1's are the same as or different from each other and independently represent an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms; R2's are the same as or different from each other and independently represent a monovalent hydrocarbon group having 1 to 12 carbon atoms and having no aliphatic unsaturated bond; R3's are the same as or different from each other and independently represent an alkyl group having 1 to 3 carbon atoms; n represents an integer of 1 to 500; and a represents 0 or 1); and a heat-conductive silicone composition which contains the organopolysiloxane as a main ingredient or a surface treatment agent for a heat-conductive filler and can exhibit satisfactory handleability even when the heat-conductive filler is contained in a large amount.

Description

[Technical field]

[0001] The present invention relates to a novel organopolysiloxane, a method for producing the same, and a thermally conductive silicone composition that uses the organopolysiloxane. [Background technology]

[0002] Patent documents 1 to 3 disclose that organopolysiloxanes having a silicon atom-bonded hydrolyzable group at one end of the molecular chain act as surface treatment agents for thermally conductive fillers to obtain silicone compositions with high thermal conductivity by filling a large amount of thermally conductive fillers. However, even if such organopolysiloxanes are used, there is a problem that when attempting to highly fill a thermally conductive filler such as alumina, the viscosity of the obtained silicone composition increases rapidly, and the handling workability and moldability are significantly reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-213133 A [Patent Document 2] JP 2004-262972 A [Patent Document 3] JP 2008-038137 A Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to provide a novel organopolysiloxane which has aliphatically unsaturated monovalent hydrocarbon groups at both molecular chain terminals and a silicon-bonded hydrolyzable group at one molecular chain terminal, and to provide a method for producing such a novel organopolysiloxane. A further object of the present invention is to provide a thermally conductive silicone composition which uses such an organopolysiloxane as a surface treatment agent for a thermally conductive filler or as a main component, and which has good handling and workability even when it contains a large amount of thermally conductive filler. [Means for solving the problem]

[0005] The organopolysiloxane of the present invention has the general formula: [ka] (In the formula, R 1 are the same or different aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms, and R 2 are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds; R 3 are the same or different alkyl groups having 1 to 3 carbon atoms, n is an integer of 1 to 500, and a is 0 or 1. It is expressed as:

[0006] The above organopolysiloxane is suitable as a surface treatment agent for inorganic powders, and is particularly suitable as a surface treatment agent for thermally conductive powders.

[0007] The method for producing an organopolysiloxane of the present invention comprises reacting a compound represented by the general formula: [ka] (In the formula, R 1 is an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R 2 are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds, and n is an integer of 1 to 500. and an organopolysiloxane represented by the general formula: R 1 R 2 a Si(OR 3 ) (3-a) (In the formula, R 1 is the same as or different from the above, an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R 2 is the same as or different from the above, a monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bonds, R 3are the same or different alkyl groups having 1 to 3 carbon atoms, and a is 0 or 1. The present invention is characterized in that the above-mentioned alkoxysilane represented by the following formula (1) is subjected to a dealcoholization condensation reaction.

[0008] The thermally conductive silicone composition of the present invention comprises: (A) General formula: [ka] (In the formula, R 1 are the same or different aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms, and R 2 are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds; R 3 are the same or different alkyl groups having 1 to 3 carbon atoms, n is an integer of 1 to 500, and a is 0 or 1. and an organopolysiloxane represented by the formula: (B) Thermally conductive filler At least one of the following:

[0009] The average particle size of component (B) is preferably 0.01 to 100 μm. Component (B) is preferably an alumina powder, and more preferably a mixture of (B1) a spherical or rounded alumina powder having an average particle size of 5 to 50 μm (but excluding 5 μm) and (B2) a spherical or irregularly shaped alumina powder having an average particle size of 0.1 to 5 μm. In particular, when the component (B1) is a mixture of components (B2), the mixture is preferably made up of 30 to 90 mass % of component (B1) and 10 to 70 mass % of component (B2).

[0010] In the above composition, the content of the component (B) is preferably within the range of 500 to 3,000 parts by mass per 100 parts by mass of the component (A).

[0011] The above composition is preferably further blended with (C) a crosslinking agent to form a curable thermally conductive silicone composition. Effect of the Invention

[0012] The organopolysiloxane of the present invention is a novel compound that has aliphatically unsaturated monovalent hydrocarbon groups at both molecular chain terminals and a silicon-bonded hydrolyzable group at one molecular chain terminal, and the thermally conductive silicone composition of the present invention uses this type of organopolysiloxane as a surface treatment agent for a thermally conductive filler or as a base compound, and is therefore characterized by good handling and workability, even when a large amount of thermally conductive filler is contained in order to obtain a silicone composition with high thermal conductivity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] First, the organopolysiloxane of the present invention will be described in detail. The organopolysiloxane of the present invention has the general formula: [ka] It is expressed as:

[0014] In the above formula, R 1 are the same or different aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms, and specific examples thereof include linear alkenyl groups such as vinyl, allyl, butenyl, hexenyl, decenyl, undecenyl, and dodecenyl; branched alkenyl groups such as isopropenyl, 2-methyl-2-propenyl, and 2-methyl-10-undecenyl; aliphatic unsaturated cyclic alkyl groups such as vinylcyclohexyl; aliphatic unsaturated group-containing aryl groups such as vinylphenyl; and aliphatic unsaturated group-containing aralkyl groups such as vinylbenzyl and vinylphenethyl. R is preferably a linear alkenyl group, and particularly preferably a vinyl, allyl, or hexenyl group. 1 The position of the aliphatic unsaturated bond in R 1 is preferably located farther away from the silicon atom to which it is bonded.

[0015] In addition, in the above formula, R 2are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds. Specific examples include linear alkyl groups such as methyl, ethyl, propyl, and butyl groups; branched alkyl groups such as isopropyl, tert-butyl, and tert-pentyl groups; cyclic alkyl groups such as cyclopentyl and cyclohexyl groups; aryl groups such as phenyl, tolyl, and xylyl groups; aralkyl groups such as benzyl and phenethyl groups; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl groups. Preferably, they are alkyl groups or aryl groups, more preferably alkyl groups having 1 to 4 carbon atoms, and particularly preferably methyl or ethyl groups.

[0016] In addition, in the above formula, R 3 are the same or different alkyl groups having 1 to 3 carbon atoms, specific examples of which include a methyl group, an ethyl group, and a propyl group, and preferably a methyl group or an ethyl group.

[0017] In the above formula, n is an integer of 1 to 500, and preferably n is at least 5, at least 10, at least 15, or at least 20, and at most 400, at most 300, or at most 200. The range of n can be any range combining the upper and lower limits above. This is because if n is equal to or greater than the lower limit of the above range, volatility is poor, whereas if n is equal to or less than the upper limit of the above range, the surface of the inorganic filler, particularly the thermally conductive filler, can be sufficiently treated.

[0018] In the above formula, a is 0 or 1, and is preferably 0.

[0019] Methods for preparing such organopolysiloxanes include, for example, those represented by the general formula: [ka] and an organopolysiloxane represented by the general formula: R 1 R 2 a Si(OR3 ) (3-a) An example of the method is a method of subjecting an alkoxysilane represented by the following formula (1) to a dealcoholization condensation reaction.

[0020] R in the above organopolysiloxane 1 , R 2 and n are the same as above. For example, as disclosed in U.S. Pat. No. 5,486,635 (JP Patent Publication No. 7-292109) or JP Patent Publication No. 10-7801, such organopolysiloxanes can be prepared by using alkyllithium or lithium silanolate as a polymerization initiator, and subjecting cyclic trisiloxane to a non-equilibrium polymerization reaction in the presence or absence of an organosilane or organosiloxane having a hydroxyl group at one end of the molecular chain as a molecular weight regulator, and then terminating the non-equilibrium polymerization reaction with an acid. It is preferable to previously silylate or acetylate a trace amount of silanol-containing impurities present in the cyclic trisiloxane, and then carry out the non-equilibrium polymerization reaction in the presence of a nitrile compound or ester compound and a polar solvent having no active hydrogen. This makes it possible to suppress the by-production of dimerization reactions and equilibration reactions of α-hydroxydiorganopolysiloxanes that occur as side reactions during polymerization of cyclic trisiloxanes, such as diorganopolysiloxanes having non-functional terminals and diorganopolysiloxanes having functional terminals.

[0021] In addition, R in the alkoxysilane 1 , R 2 and R 3 is the same as above. In addition, a in the above alkoxysilane is 0 or 1, and preferably 0. Examples of such alkoxysilanes include vinyltrimethoxysilane, allyltrimethoxysilane, vinyltriethoxysilane, allyltriethoxysilane, vinyldimethoxyethoxysilane, hexenyltrimethoxysilane, hexenyltriethoxysilane, octenyltrimethoxysilane, and octenyltriethoxysilane. It is preferable to add this alkoxysilane in an amount of at least equimolar to the organopolysiloxane, and it is preferable to add an excess amount in order to suppress by-products.

[0022] The organopolysiloxane of the present invention can be prepared by subjecting the above-mentioned organopolysiloxane and the above-mentioned alkoxysilane to a dealcoholization condensation reaction. In order to promote this dealcoholization condensation reaction, an acid catalyst may be added. Examples of this acid include hydrochloric acid, sulfuric acid, acetic acid, and propionic acid. This dealcoholization condensation reaction proceeds even at room temperature, but can be promoted by heating, and it is particularly preferable to remove the alcohol produced by the condensation reaction under reduced pressure.

[0023] Such organopolysiloxanes of the present invention include, for example, those represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] Dimethylpolysiloxane represented by the formula: [ka] When the organopolysiloxane of the present invention is used as a surface treatment agent for inorganic powders described below, it may contain a small amount of by-products derived from the above polymerization initiator.

[0024] Such organopolysiloxane of the present invention is useful as a surface treatment agent for inorganic powder, and is particularly useful as a surface treatment agent for thermally conductive powder.The inorganic powder to which the organopolysiloxane of the present invention can be applied includes metal powders such as aluminum powder, copper powder, nickel powder, etc.; metal oxide powders such as alumina powder, magnesium oxide powder, beryllium oxide powder, chromium oxide powder, titanium oxide powder, zinc oxide powder, iron oxide powder, etc.; metal nitride powders such as boron nitride powder, aluminum nitride powder, etc.; metal carbide powders such as boron carbide powder, titanium carbide powder, silicon carbide powder, etc.; metal oxide powders coated with metal to give electrical conductivity to the surface; and other examples include fumed silica, hydrophobized fumed silica, precipitated silica, fused silica, diatomaceous earth, talc, calcium carbonate, manganese carbonate, and cerium hydroxide.The method for treating the surface of these inorganic powders is not limited, and can be treated by a well-known method.

[0025] Next, the thermally conductive silicone composition of the present invention will be described in detail. The thermally conductive silicone composition of the present invention comprises: (A) General formula: [ka] (In the formula, R 1 is an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R 2 are the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds, R 3 is an alkyl group having 1 to 3 carbon atoms, n is an integer of 1 to 500, and a is 0 or 1. and an organopolysiloxane represented by the formula: (B) Thermally conductive filler The present invention is characterized in that it comprises at least

[0026] Component (A) is the organopolysiloxane described above, and acts as the main component of the composition or as a surface treatment agent for component (B). In addition to component (A), the composition may contain organopolysiloxanes that are by-products derived from the polymerization initiator used in preparing component (A) and other organopolysiloxanes. When any organopolysiloxane is the main component of the composition, component (A) acts solely as a surface treatment agent for component (B).

[0027] Examples of organopolysiloxanes other than component (A) include those having a linear, branched, partially branched linear, or dendritic (dendrimer) molecular structure, and linear or partially branched linear structures are preferred. Specifically, dimethylpolysiloxanes capped with dimethylvinylsiloxy groups at both molecular chain terminals, dimethylpolysiloxanes capped with methylphenylvinylsiloxy groups at both molecular chain terminals, dimethylsiloxane-methylphenylsiloxane copolymers capped with dimethylvinylsiloxy groups at both molecular chain terminals, dimethylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxy groups at both molecular chain terminals, dimethylsiloxane-methylvinylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals, methyl(3,3,3-trifluoropropyl)polysiloxanes capped with dimethylvinylsiloxy groups at both molecular chain terminals, dimethylsiloxane-methylvinylsiloxane copolymers capped with silanol groups at both molecular chain terminals, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped with silanol groups at both molecular chain terminals, formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: (CH3)2(CH2=CH)SiO 1 / 2 Siloxane units represented by the formula: CH3SiO 3 / 2 Siloxane units represented by the formula: (CH3)2SiO 2 / 2and mixtures of two or more of these.

[0028] The viscosity of such organopolysiloxane at 25°C is not limited, but is preferably in the range of 20 to 100,000 mPa·s, more preferably in the range of 50 to 100,000 mPa·s, even more preferably in the range of 50 to 50,000 mPa·s, and particularly preferably in the range of 100 to 50,000 mPa·s. This viscosity can be measured by a rotational viscometer in accordance with JIS K7117-1. This is because if the viscosity at 25°C is below the lower limit of the above range, the physical properties of the obtained composition are significantly reduced, while if it exceeds the upper limit of the above range, the handling and workability of the obtained composition are significantly reduced.

[0029] The thermally conductive filler of component (B) is a component that imparts thermal conductivity to the composition, and examples thereof include metal-based powders such as aluminum powder, copper powder, and nickel powder; metal oxide-based powders such as alumina powder, magnesium oxide powder, beryllium oxide powder, chromium oxide powder, and titanium oxide powder; metal nitride-based powders such as boron nitride powder and aluminum nitride powder; metal carbide-based powders such as boron carbide powder, titanium carbide powder, and silicon carbide powder; metal oxide-based powders coated with a metal to impart electrical conductivity to the surface, and mixtures of two or more of these. The shape of component (B) may be, for example, spherical, round, needle-like, disc-like, rod-like, or irregular. When electrical insulation is required for the composition or the crosslinked product of the composition, component (B) is preferably a metal oxide-based powder, a metal nitride-based powder, or a metal carbide-based powder, and particularly preferably an alumina powder.

[0030] The average particle size of the (B) component is not limited, but is preferably within the range of 0.1 to 100 μm, and more preferably within the range of 0.1 to 50 μm. When an alumina powder is used as the (B) component, it is preferable that the (B1) is a mixture of a spherical alumina powder having an average particle size of 5 to 50 μm (excluding 5 μm) and a spherical or irregular alumina powder having an average particle size of 0.1 to 5 μm. In this mixture, the content of the (B1) component is preferably within the range of 30 to 90 mass%, and the content of the (B2) component is preferably within the range of 10 to 70 mass%.

[0031] In the present composition, the content of component (B) is not limited, but in order to provide good thermal conductivity, the volume % is preferably at least 30 volume % of the present composition, more preferably in the range of 30 to 90 volume %, more preferably in the range of 60 to 90 volume %, and particularly preferably in the range of 80 to 90 volume %. Similarly, the mass % is preferably at least 50 mass % of the present composition, more preferably in the range of 70 to 98 mass %, and particularly preferably in the range of 90 to 97 mass %. Specifically, when the (A) component is the main component, the content of the (B) component is preferably within the range of 500 to 3,500 parts by mass, more preferably within the range of 500 to 3,000 parts by mass, and particularly preferably within the range of 800 to 3,000 parts by mass, relative to 100 parts by mass of the (A) component. On the other hand, when the (A) component acts as a surface treatment agent for the (B) component and an organopolysiloxane other than the (A) component is the main component, the content of the (B) component is preferably within the range of 500 to 3,500 parts by mass, more preferably within the range of 500 to 3,000 parts by mass, and particularly preferably within the range of 800 to 3,000 parts by mass, relative to 100 parts by mass of this organopolysiloxane. This is because, if the content of the (B) component is less than the lower limit of the above range, the thermal conductivity or electrical conductivity of the obtained composition becomes insufficient, and, on the other hand, if the content of the (B) component is more than the upper limit of the above range, the viscosity of the obtained composition becomes high, a uniform composition cannot be obtained, and the handling workability is significantly reduced.

[0032] The composition may be in the form of a non-crosslinkable grease, or may further contain a crosslinking agent (C) to make it crosslinkable and thicken or harden it by crosslinking. The crosslinking reaction is not limited, and examples of the crosslinking reaction include a hydrosilylation reaction, a condensation reaction, and a free radical reaction by an organic peroxide.

[0033] When the composition undergoes a hydrosilylation reaction, component (C) comprises an organopolysiloxane having an average of two or more silicon-bonded hydrogen atoms per molecule, and a platinum catalyst. The groups bonded to silicon atoms in this organopolysiloxane include the same linear alkyl groups, branched alkyl groups, cyclic alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups as described above, with alkyl groups and aryl groups being preferred, and methyl and phenyl groups being particularly preferred. The kinetic viscosity of this organopolysiloxane at 25°C is not limited, but is preferably 1 to 1,000 mm 2 / s, and particularly preferably 1 to 500 mm 2 The kinematic viscosity is in the range of 1 / s. Note that the kinematic viscosity can be measured by an Ubbelohde viscometer conforming to JIS Z8803.

[0034] The molecular structure of such organopolysiloxane is not limited, and examples thereof include linear, branched, partially branched linear, cyclic, and dendritic (dendrimer) structures. Examples of such organopolysiloxane include homopolymers having these molecular structures, copolymers consisting of these molecular structures, and mixtures thereof.

[0035] Examples of such organopolysiloxanes include dimethylpolysiloxanes blocked at both molecular chain terminals with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers blocked at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers blocked at both molecular chain terminals with dimethylhydrogensiloxy groups, and the formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: (CH3)2HSiO 1 / 2 Siloxane units represented by the formula: SiO 4 / 2 and mixtures of two or more of these.

[0036] In the present composition, the content of this organopolysiloxane is an amount sufficient to crosslink the present composition, specifically, the amount of silicon-bonded hydrogen atoms in this component is preferably within the range of 0.1 to 10 moles, more preferably within the range of 0.1 to 5 moles, and particularly preferably within the range of 0.1 to 3.0 moles, per mole of aliphatic unsaturated monovalent hydrocarbon groups in component (A) and any organopolysiloxane other than component (A).This is because if the content of this component is below the lower limit of the above range, the resulting composition will not be sufficiently crosslinked, while if it exceeds the upper limit of the above range, the resulting crosslinked product will be a very hard cured product, and many cracks will occur on the surface.

[0037] The platinum catalyst is a catalyst for promoting crosslinking of the present composition, and examples thereof include chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum olefin complexes, platinum alkenylsiloxane complexes, and platinum carbonyl complexes.

[0038] In the present composition, the content of the platinum catalyst is an amount sufficient to promote crosslinking of the present composition, specifically, the amount of platinum metal in this component is preferably within the range of 0.01 to 1,000 ppm by mass relative to component (A) and any organopolysiloxane other than component (A), and more preferably within the range of 0.1 to 500 ppm. This is because if the content of this component is below the lower limit of the above range, the resulting composition will not be sufficiently crosslinked, and on the other hand, even if the content exceeds the upper limit of the above range, the crosslinking reaction of the resulting composition will not be significantly promoted.

[0039] In particular, when the present composition crosslinks by hydrosilylation reaction, in order to adjust the crosslinking rate and improve the handling and workability, it is preferable to contain a reaction inhibitor such as acetylene compounds such as 2-methyl-3-butyn-2-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, ene-yne ​​compounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne, alkenyl group-containing cyclosiloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, and others, hydrazine compounds, phosphine compounds, mercaptan compounds, etc. The content of this reaction inhibitor is not limited, but is preferably within the range of 0.0001 to 1.0 mass% of the present composition.

[0040] In addition, when the present composition is crosslinked by a condensation reaction, the component (C) is composed of a silane having at least three silicon-bonded hydrolyzable groups in one molecule, or a partial hydrolyzate thereof, and / or a catalyst for the condensation reaction. Examples of the silicon-bonded hydrolyzable groups in this silane include the same alkoxy group, alkoxyalkoxy group, acyloxy group, ketoxime group, alkenoxy group, amino group, aminoxy group, and amide group as described above. In addition to the above hydrolyzable groups, the silicon atom of this silane may be bonded with, for example, the same linear alkyl group, branched alkyl group, cyclic alkyl group, alkenyl group, aryl group, aralkyl group, and halogenated alkyl group as described above. Examples of such silanes or partial hydrolyzates thereof include methyltriethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and ethylorthosilicate.

[0041] In the present composition, the content of the silane or its partial hydrolysate is an amount sufficient to crosslink the present composition, and specifically, it is preferably within the range of 0.01 to 20 parts by mass, and particularly preferably within the range of 0.1 to 10 parts by mass, per 100 parts by mass of component (A) or any organopolysiloxane other than component (A). This is because, if the content of the silane or its partial hydrolysate is below the lower limit of the above range, the storage stability of the obtained composition decreases and the adhesiveness decreases, whereas, if it exceeds the upper limit of the above range, the crosslinking reaction of the obtained composition becomes significantly slow.

[0042] The condensation reaction catalyst is not essential, for example, when a silane having a hydrolyzable group such as an aminoxy group, an amino group, or a ketoxime group is used as component (C). Examples of the condensation reaction catalyst include organic titanate esters such as tetrabutyl titanate and tetraisopropyl titanate; organic titanium chelate compounds such as diisopropoxybis(acetylacetate)titanium and diisopropoxybis(ethylacetoacetate)titanium; organic aluminum compounds such as aluminum tris(acetylacetonate) and aluminum tris(ethylacetoacetate); organic aluminum compounds such as zirconium tetra(acetylacetonate) and zirconium tetrabutylate; dibutyltin dioctoate and dibutyltin dioctoate; Examples of suitable organic tin compounds include tin dilaurate, butyltin 2-ethylhexoate, and other organic carboxylic acids, such as metal salts of tin naphthenate, tin oleate, tin butyrate, cobalt naphthenate, and zinc stearate; amine compounds and their salts, such as hexylamine and dodecylamine phosphate; quaternary ammonium salts, such as benzyltriethylammonium acetate; lower fatty acid salts of alkali metals, such as potassium acetate and lithium nitrate; dialkylhydroxylamines, such as dimethylhydroxylamine and diethylhydroxylamine; and guanidyl group-containing organic silicon compounds.

[0043] In the present composition, the content of the condensation reaction catalyst may be an amount sufficient to promote crosslinking of the present composition, and specifically, it is preferably within the range of 0.01 to 20 parts by mass, and particularly preferably within the range of 0.1 to 10 parts by mass, per 100 parts by mass of component (A) or any organopolysiloxane other than component (A). This is because, when the catalyst is essential, if the content of the catalyst is below the lower limit of the above range, the resulting composition will not be sufficiently crosslinked, whereas if it exceeds the upper limit of the above range, the storage stability of the resulting composition will decrease.

[0044] In addition, when the present composition crosslinks by a free radical reaction with an organic peroxide, component (C) is an organic peroxide, such as benzoyl peroxide, dicumyl peroxide, 2,5-dimethylbis(2,5-tert-butylperoxy)hexane, di-tert-butyl peroxide, or tert-butyl perbenzoate.

[0045] The content of this organic peroxide is an amount sufficient to crosslink the composition, and specifically, it is preferably an amount within the range of 0.1 to 5 parts by mass per 100 parts by mass of the above component (A) or any organopolysiloxane other than component (A).

[0046] Furthermore, the composition may contain other optional components, so long as they do not impair the object of the present invention, such as fillers such as fumed silica, precipitated silica, and fumed titanium oxide, and fillers whose surfaces have been hydrophobized with an organosilicon compound; as well as pigments, dyes, fluorescent dyes, heat resistance additives, flame retardants other than triazole-based compounds, plasticizers, and adhesion promoters.

[0047] When the present composition is crosslinkable, the crosslinking method is not limited, and examples thereof include a method in which the present composition is molded and then left at room temperature, and a method in which the present composition is molded and then heated to 50 to 200° C. In addition, the properties of the crosslinked product thus obtained are not limited, and examples thereof include a thickened grease-like material, a hardened gel-like material, a low hardness rubber-like material, or a high hardness rubber-like material, and the crosslinked product can be sufficiently adhered to a member as a heat dissipation material. EXAMPLES

[0048] The organopolysiloxane, its production method, and thermally conductive silicone composition of the present invention will be described in detail with reference to examples and comparative examples. Note that the properties in the examples are values ​​measured at 25°C.

[0049] [Example 1] In a 1L flask, 211g (950.5mmol) of 1,1,3,3,5,5-hexamethylcyclotrisiloxane and 165g of toluene were mixed under a nitrogen stream and azeotropically dehydrated for 1 hour. After dehydration, the mixture was cooled to 30°C, and 5.5ml of a 1.6N hexane solution of n-butyllithium (n-butyllithium = 8.8mmol) was added and stirred at 30°C for 10 minutes. Next, 0.88g (8.12mmol) of trimethylchlorosilane was added to the mixture and stirred at 30°C for 30 minutes, after which a mixture of 11.0g (107.6mmol) of vinyldimethylsilanol, 16.9g of dimethylformamide and 52.7g of acetonitrile was added to start the non-equilibrium polymerization reaction. After 6.5 hours had elapsed since the start of the non-equilibrium polymerization reaction, 1.37 g (22.74 mmol) of acetic acid was added to the reaction mixture to terminate the non-equilibrium polymerization reaction, yielding an intermediate dimethylpolysiloxane with one molecular end blocked by dimethylvinylsiloxy groups and the other molecular end blocked by hydroxydimethylsiloxy groups. The conversion of 1,1,3,3,5,5-hexamethylcyclotrisiloxane was 95%. Next, low boiling point substances were distilled off from the intermediate by heating at 95°C under reduced pressure.

[0050] Next, 170.5 g (1150.2 mmol) of vinyltrimethoxysilane and 0.53 g (8.83 mmol) of acetic acid were added to the intermediate from which the low boilers had been distilled off under reduced pressure, and the mixture was stirred at 130° C. for 4 hours, after which the low boilers were distilled off under reduced pressure at 150° C. After cooling, the salt produced when the non-equilibrium polymerization reaction was stopped was filtered off, yielding 212 g of dimethylpolysiloxane.

[0051] This dimethylpolysiloxane 29 Analysis by Si-NMR revealed that the average formula was: [ka] Dimethylpolysiloxane represented by the average formula: [ka] It was found that the compound was a mixture of dimethylpolysiloxane represented by the formula (1) with a mass ratio of 92:8 (vinyl group content: 2.6 mass %).

[0052] [Example 2] The same procedure as in Example 1 was repeated, except that the amount of vinyldimethylsilanol was 3.39 g (33.16 mmol), and the amounts of vinyltrimethoxysilane and acetic acid added to the intermediate from which the low boilers had been distilled off under reduced pressure were 53.2 g (358.9 mmol), and 0.28 g (4.66 mmol), respectively, of dimethylpolysiloxane was obtained (191 g).

[0053] This dimethylpolysiloxane 29 Analysis by Si-NMR revealed that the average formula was: [ka] Dimethylpolysiloxane represented by the average formula: [ka] It was found that the compound was a mixture of dimethylpolysiloxane represented by the formula (I) in a mass ratio of 81:19 (vinyl group content: 0.91 mass %).

[0054] [Example 3] In a 1L flask, 221g (995.5mmol) of 1,1,3,3,5,5-hexamethylcyclotrisiloxane and 173g of toluene were mixed under a nitrogen stream and azeotropically dehydrated for 1 hour. After dehydration, the mixture was cooled to 30°C, and 12.0ml of a 1.6N hexane solution of n-butyllithium (n-butyllithium = 19.2mmol) was added thereto and stirred at 30°C for 1 hour. Next, 0.92g (9.01mmol) of acetic anhydride was added to the mixture, which was stirred at 100°C for 30 minutes and then cooled to 30°C. A mixture of 1.87g (18.29mmol) of vinyldimethylsilanol, 18.1g of dimethylformamide and 55.1g of acetonitrile was added to the mixture at 30°C to initiate a non-equilibrium polymerization reaction. 1.7 hours after the start of the non-equilibrium polymerization reaction, 1.47 g (24.48 mmol) of acetic acid was added to the reaction mixture to terminate the non-equilibrium polymerization reaction, yielding an intermediate dimethylpolysiloxane with one molecular chain end blocked by dimethylvinylsiloxy and the other molecular chain end blocked by hydroxydimethylsiloxy. The conversion of 1,1,3,3,5,5-hexamethylcyclotrisiloxane was 98%. Next, low boiling point substances were distilled off from the intermediate by heating at 95°C under reduced pressure.

[0055] Next, 30.1 g (203.1 mmol) of vinyltrimethoxysilane and 0.18 g (3.00 mmol) of acetic acid were added to the intermediate from which the low boilers had been distilled off under reduced pressure, and the mixture was stirred at 130° C. for 4 hours. The low boilers were then distilled off under reduced pressure at 150° C. After cooling, the salt formed when the non-equilibrium polymerization reaction was stopped was filtered off, yielding 205 g of methylpolysiloxane.

[0056] This dimethylpolysiloxane 29 Analysis by Si-NMR revealed that the average formula was: [ka] Dimethylpolysiloxane represented by the average formula: [ka] It was found that the compound was a mixture of dimethylpolysiloxane represented by the formula (I) in a mass ratio of 78:22 (vinyl group content = 0.49 mass %).

[0057] [Example 4] The same procedure as in Example 3 was repeated, except that the amount of vinyldimethylsilanol was 0.84 g (8.22 mmol), and the amounts of vinyltrimethoxysilane and acetic acid added to the intermediate from which the low boilers had been distilled off under reduced pressure were 16.8 g (113.3 mmol), and 0.20 g (3.33 mmol), respectively, of dimethylpolysiloxane were obtained (197 g).

[0058] This dimethylpolysiloxane 29 Analysis by Si-NMR revealed that the average formula was: [ka] Dimethylpolysiloxane represented by the average formula: [ka] It was found that the compound was a mixture of dimethylpolysiloxane represented by the formula (I) in a mass ratio of 65:35 (vinyl group content: 0.24 mass %).

[0059] [Examples 5 to 8, Comparative Examples 1 to 2] Using the components listed below, thermally conductive silicone compositions were prepared according to the formulations shown in Tables 1 and 2. The content of the crosslinking agent in the thermally conductive silicone composition was such that the crosslinking agent contained approximately 1.4 moles of silicon-bonded hydrogen atoms per mole of vinyl groups in component (A).

[0060] The following components were used as component (A): (A-1): Dimethylpolysiloxane prepared in Example 1 (A-2): Dimethylpolysiloxane prepared in Example 2 (A-3): Dimethylpolysiloxane prepared in Example 3 (A-4): Dimethylpolysiloxane prepared in Example 4 (A-5): Average formula: [ka] Dimethylpolysiloxane (vinyl group content = 0.95% by mass) represented by the formula (A-6): Average formula: [ka] Dimethylpolysiloxane (vinyl group content = 0.23% by mass) represented by the formula

[0061] The following components were used as component (B): (B-1): Alumina powder having an average particle size (d50) of 34.5 μm (trade name: DAW-45, manufactured by Denka Co., Ltd.) (B-2): Alumina powder with an average particle size (d50) of 2 μm (product name: CB-P02, manufactured by Showa Denko K.K.) (B-3): Alumina powder with an average particle size (d50) of 0.3 μm (product name: ASFP-02, manufactured by Denka Co., Ltd.)

[0062] The following components were used as crosslinking agents: (C-1): Dimethylsiloxane-methylhydrogensiloxane copolymer terminated at both ends with trimethylsiloxy groups (content of silicon-bonded hydrogen atoms = approx. 0.76% by mass) (C-2): Dimethylpolysiloxane terminated at both ends of the molecular chain with dimethylhydrogensiloxy groups (content of silicon-bonded hydrogen atoms = approximately 0.015% by mass)

[0063] The following components were used as catalysts for the crosslinking reaction: (D-1): A solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in dimethylpolysiloxane terminated at both molecular chain ends with vinyldimethylsiloxy groups, with a viscosity of 400 mPa·s (platinum content = approximately 0.6% by mass).

[0064] The following components were used as inhibitors of the crosslinking reaction: (E-1): 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane

[0065] [Evaluation of the physical properties of thermally conductive silicone compositions and their cured products] The viscosity of the thermally conductive silicone composition was measured at 25°C using a rheometer MCR102 (manufactured by Anton Paar). The measurement was performed using a 20 mm plate, rotating at a shear rate of 5 / s for 30 seconds, leaving it for 10 minutes, and then sweeping the shear rate from 0.01 / s to 0.075 / s. Table 1 shows the viscosity at a shear rate of 0.075 / s.

[0066] The thermally conductive silicone composition was cured by heating at 150°C for 60 minutes to produce a silicone cured product with a width of about 10 mm, length of about 50 mm, and thickness of about 2 mm. The modulus of this silicone cured product due to torsional deformation was measured at 23°C using a rheometer MCR302 (manufactured by Anton Paar). The measurement was performed by sweeping the frequency from 0.01 Hz. Table 1 shows the storage modulus and loss tangent at 1 Hz.

[0067] [Thermal resistance measurement] Measurements were performed under a load of 50N using a thermal resistance measuring device (Hitachi). An appropriate amount of silicone grease (Shin-Etsu Chemical Co., Ltd., G-750) was applied to a silicone cured product measuring 1 mm thick and 1 cm square, and the sample was sandwiched between the heating shaft and the cooling shaft. After the sample reached the set temperature (50°C ± 1°C), measurements were started. The thermal resistance of the silicone grease, which had been measured in advance, was subtracted from the obtained thermal resistance value to obtain the thermal resistance value of the sample (°C / W). Measurements were performed three times for each sample, and the average values ​​are shown in Table 1.

[0068] [Table 1]

[0069] [Table 2]

[0070] From the results of Tables 1 and 2, in Examples 5 to 8, by using components (A-1) to (A-4), even if components (B-1) to (B-3) were contained at 95 mass%, a paste-like state could be maintained, and a cured product could be obtained by heat curing. From these results, it is considered that components (A-1) to (A-4) have the effect of reducing viscosity and are incorporated as designed as part of the crosslinked structure. [Industrial Applicability]

[0071] The organopolysiloxane of the present invention is a novel compound and can be used as a surface treatment agent for inorganic powders, particularly as a surface treatment agent for thermally conductive powders. Furthermore, the silicone composition of the present invention uses such an organopolysiloxane as a surface treatment agent for thermally conductive fillers or as a main component, so that even if a large amount of thermally conductive filler is contained in order to obtain a silicone composition with high thermal conductivity, the silicone composition has good handling properties and can be used as a heat dissipation agent for electric and electronic parts.

Claims

1. General formula: 【Chemistry 1】 (In the formula, R １ are the same or different aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms, R ２ are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds; R ３ are the same or different alkyl groups having 1 to 3 carbon atoms, n is an integer of 10 to 500, and a is 0 or 1. Organopolysiloxane represented by the formula:

2. 2. The organopolysiloxane according to claim 1, which is a surface treatment agent for inorganic powder.

3. 3. The organopolysiloxane according to claim 2, wherein the inorganic powder is a thermally conductive powder.

4. General formula: 【Chemistry 2】 (In the formula, R １ is an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R ２ are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds, and n is an integer of 10 to 500. and an organopolysiloxane represented by the general formula: R １ R ２ ａ Si(OR ３ ) (３－ａ) (In the formula, R １ is the same as or different from the above, an aliphatic unsaturated monovalent hydrocarbon group having 2 to 12 carbon atoms, R ２ is the same as or different from the above, a monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bonds, R ３ are the same or different alkyl groups having 1 to 3 carbon atoms, and a is 0 or 1.

2. A method for producing an organopolysiloxane according to claim 1, characterized in that an alkoxysilane represented by the following formula (1) is subjected to a dealcoholization condensation reaction.

5. (A) General formula: 【Chemistry 3】 (In the formula, R １ are the same or different aliphatic unsaturated monovalent hydrocarbon groups having 2 to 12 carbon atoms, R ２ are the same or different and are monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds; R ３ are the same or different alkyl groups having 1 to 3 carbon atoms, n is an integer of 10 to 500, and a is 0 or 1. and an organopolysiloxane represented by the formula: (B) Thermally conductive filler A thermally conductive silicone composition comprising at least

6. 6. The thermally conductive silicone composition according to claim 5, wherein component (B) has an average particle size of 0.01 to 100 μm.

7. 6. The thermally conductive silicone composition according to claim 5, wherein component (B) is an alumina powder.

8. The component (B) is １ ) spherical or rounded alumina powder having an average particle size of 5 to 50 μm (but not including 5 μm); and (B ２ 8. The thermally conductive silicone composition according to claim 7, comprising a mixture of alumina powder having an average particle size of 0.1 to 5 μm and a spherical or irregularly shaped alumina powder.

9. The component (B) is １ ) component 30 to 90 mass % and (B ２ 9. The thermally conductive silicone composition according to claim 8, comprising 10 to 70 mass % of the polysiloxane copolymer.

10. 6. The thermally conductive silicone composition according to claim 5, wherein the amount of component (B) is 500 to 3,000 parts by mass per 100 parts by mass of component (A).

11. The thermally conductive silicone composition according to claim 5 , further comprising (C) a crosslinking agent.

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