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  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
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  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
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  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
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  • C08K2201/001—Conductive additives
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  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/002—Physical properties
  • C08K2201/005—Additives being defined by their particle size in general
• • C—CHEMISTRY; METALLURGY
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  • C08K2201/006—Additives being defined by their surface area
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  • C08K3/10—Metal compounds
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  • C08K9/00—Use of pretreated ingredients
  • C08K9/04—Ingredients treated with organic substances
  • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
  • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
• • C—CHEMISTRY; METALLURGY
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  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2207/00—Properties characterising the ingredient of the composition
  • C08L2207/32—Properties characterising the ingredient of the composition containing low molecular weight liquid component
  • C08L2207/324—Liquid component is low molecular weight polymer

Definitions

• the present invention relates to a thermally conductive composition and its cured product.
• a thermally conductive composition is composed of a matrix such as a resin filled with a powder (thermally conductive powder) that imparts thermal conductivity.
• a powder thermally conductive powder
• metal oxides such as alumina and metal nitrides such as aluminum nitride are used.
• thermoly conductive filler and one or more selected from the group consisting of an alkoxysilyl group-containing compound and dimethylpolysiloxane are contained, and the thermally conductive filler has an average particle size of 50 ⁇ m.
• a thermally conductive polysiloxane composition is disclosed in which the content ratio of aluminum nitride particles having a specific shape and having an average particle size of 10 ⁇ m or more and less than 50 ⁇ m is 50:50 to 95:5 on a mass basis.
• organopolysiloxane is used as a base polymer, and as a thermally conductive filler, aluminum nitride having an average particle size of 10 to 100 ⁇ m and crushed alumina having an average particle size of 0.1 to 5 ⁇ m are included. 15 to 55% by mass of aluminum nitride and crushed alumina, and 60 to 95% by weight of the total amount of aluminum nitride and crushed alumina in the thermally conductive silicone composition.
• a silicone composition is disclosed.
• Patent Document 3 discloses that a thermally conductive filler and one or more selected from the group consisting of an alkoxysilyl group-containing compound and dimethylpolysiloxane are contained, and the thermally conductive filler has two different average particle diameters.
• a thermally conductive polysiloxane composition comprising more than one type of thermally conductive filler and containing 20% by mass or more of amorphous aluminum nitride particles having an average particle diameter of 30 ⁇ m or more and 150 ⁇ m or less based on the total amount of the thermally conductive filler.
• organopolysiloxane is contained in a ratio of 6 to 40% by volume and a thermally conductive filler is contained in a ratio of 60 to 94% by volume, and the thermally conductive filler has an average particle size of 40 ⁇ m or more, and Composed of non-sintered crushed aluminum nitride in which fine powder with a particle size of 5 ⁇ m or less is 1% by mass or less, and a thermal conductive material other than the unsintered crushed aluminum nitride and having an average particle size of 1 ⁇ m or more, A thermally conductive silicone composition is disclosed wherein the thermally conductive material is 30-65% by volume.
• the amount of filler in the composition increases, the viscosity of the composition increases and the fluidity deteriorates.
• the heat-conducting composition is applied to a heat-generating source or the like, the workability is deteriorated, and in some cases, the object may be damaged.
• the present invention has been made to solve the above problems, and an object of the present invention is to provide a thermally conductive composition that achieves both high thermal conductivity performance and good fluidity.
• the content of the thermally conductive powder (B) is 70 to 98% by mass with respect to the total amount of the thermally conductive composition
• the thermally conductive powder (B) contains 30 to 75% by mass of aluminum nitride particles (B-1) having a cumulative volume 50% particle size of 50 ⁇ m or more and 150 ⁇ m or less with respect to the total amount of the thermally conductive powder (B).
• B-2 aluminum nitride particles
• B-3 metal oxide other than zinc oxide having a cumulative volume 50% particle size of 1 ⁇ m or more and less than 20 ⁇ m ( 5 to 15% by mass of B-3)
• B-4 zinc oxide having a particle size of 0.1 ⁇ m or more and less than 1 ⁇ m and a BET specific surface area of less than 9.0 m 2 /g at 50% of the cumulative volume.
• the metal oxide (B-3) other than zinc oxide and the zinc oxide (B-4) are both a silane coupling agent having an alkyl group having 10 to 22 carbon atoms and ⁇ -butyl- ⁇ -(2- A thermal conductive composition surface-treated with at least one surface-treating agent selected from the group consisting of trimethoxysilylethyl)polydimethylsiloxane.
• the thermal conductive composition according to [1] or [2] above, wherein the metal oxide (B-3) other than zinc oxide is alumina.
• At least one aluminum nitride particle selected from the group consisting of the aluminum nitride particles (B-1) and the aluminum nitride particles (B-2) has a silicon-containing oxide film on the surface [1]
• the curable silicone resin (A) is an addition reaction curable silicone resin.
• the addition reaction-curable silicone resin comprises an alkenyl group-containing organopolysiloxane (a-1), a hydrosilyl group-containing organopolysiloxane (a-2), and a platinum group metal-based curing catalyst (a-3).
• the thermally conductive composition according to [5] above comprising: [7] The thermally conductive composition according to any one of [1] to [6] above, further comprising dimethylsilicone oil (C). [8] The thermal conductive composition according to any one of [1] to [7] above, which has a viscosity of 50000 Pa ⁇ s or less at 25°C. [9] A cured product of the thermal conductive composition according to any one of [1] to [8] above. [10] A cured product of the thermally conductive composition according to the above [9], which has a thermal conductivity of 10.0 W/m ⁇ K or more.
• thermoly conductive composition that achieves both high thermal conductivity performance and good fluidity.
• the thermally conductive composition of the present embodiment is a thermally conductive composition containing a curable silicone resin (A) and a thermally conductive powder (B),
• the content of the thermally conductive powder (B) is 70 to 98% by mass with respect to the total amount of the thermally conductive composition
• the thermally conductive powder (B) contains 30 to 75% by mass of aluminum nitride particles (B-1) having a cumulative volume 50% particle size of 50 ⁇ m or more and 150 ⁇ m or less with respect to the total amount of the thermally conductive powder (B).
• B-2 aluminum nitride particles
• B-3 metal oxide other than zinc oxide having a cumulative volume 50% particle size of 1 ⁇ m or more and less than 20 ⁇ m ( 5 to 15% by mass of B-3)
• B-4 zinc oxide having a particle size of 0.1 ⁇ m or more and less than 1 ⁇ m and a BET specific surface area of less than 9.0 m 2 /g at 50% of the cumulative volume.
• the metal oxide (B-3) other than zinc oxide and the zinc oxide (B-4) are both a silane coupling agent having an alkyl group having 10 to 22 carbon atoms and ⁇ -butyl- ⁇ -(2- trimethoxysilylethyl) polydimethylsiloxane surface-treated with at least one surface treatment agent selected from the group consisting of polydimethylsiloxane.
• the thermally conductive composition of the present embodiment as the thermally conductive powder (B), the aluminum nitride particles (B-1), the aluminum nitride particles (B-2), the metal oxide other than zinc oxide (B- 3) and zinc oxide (B-4) in specific proportions, both high thermal conductivity and good fluidity can be achieved.
• the curable silicone resin (A) used in the present embodiment is a resin having an organopolysiloxane structure as a main chain, such as an addition reaction-curable silicone resin, a condensation reaction-curable silicone resin, an organic peroxide-curable silicone resin, or the like. is mentioned. Among them, addition reaction curing type silicone resins are preferable from the viewpoint of enhancing flexibility.
• the addition reaction-curable silicone resin has a structure in which the functional groups in two types of organopolysiloxanes are bonded by an addition reaction and crosslinked.
• organopolysiloxane (a-1) having an alkenyl group as a base polymer an organopolysiloxane (a-2) having a hydrosilyl group as a cross-linking agent, and a platinum group metal-based curing catalyst (a-3).
• Organopolysiloxane (a-1) having an alkenyl group for example, an organopolysiloxane having two or more silicon-bonded alkenyl groups in one molecule (hereinafter also referred to as alkenyl group-containing organopolysiloxane). mentioned.
• the alkenyl group-containing organopolysiloxane preferably has 2 to 20, more preferably 2 to 10 silicon-bonded alkenyl groups in one molecule.
• the alkenyl group-containing organopolysiloxane usually has a main chain basically consisting of repeating diorganosiloxane units, which may contain a branched structure as part of the molecular structure, although it may be a cyclic body, it is preferably a linear diorganopolysiloxane from the viewpoint of the mechanical strength of the cured product.
• Alkenyl groups bonded to silicon atoms include, for example, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, and the like. Among them, lower alkenyl groups such as vinyl groups and allyl groups are preferred, and vinyl groups are particularly preferred, from the viewpoints of reactivity with the hydrosilyl group-containing organopolysiloxane (a-2) and availability.
• the alkenyl group bonded to the silicon atom may be present at either a molecular chain terminal or a molecular chain non-terminal (that is, a molecular chain side chain) in the molecule of the organopolysiloxane (a-1), or although it may be present in both of these, it is preferably present at least at both ends of the molecular chain.
• the organic group bonded to a silicon atom other than the alkenyl group is an unsubstituted or substituted monovalent hydrocarbon group that may have an oxygen atom interposed therebetween, such as a methyl group, an ethyl group, a propyl group and an isopropyl group.
• butyl group isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, alkyl group such as dodecyl group; cyclopentyl group, cyclohexyl group, cycloheptyl group, etc.
• aryl groups such as phenyl, tolyl, xylyl, naphthyl and biphenylyl groups; aralkyl groups such as benzyl, phenylethyl, phenylpropyl and methylbenzyl; and carbon atoms in these groups.
• a group in which some or all of the hydrogen atoms to which is bonded is substituted with a halogen atom such as fluorine, chlorine, or bromine, or a cyano group, such as a chloromethyl group, a 2-bromoethyl group, a 3-chloropropyl group, Examples thereof include 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group and the like, methoxy group, ethoxy group, propoxy group and other alkoxy groups.
• a halogen atom such as fluorine, chlorine, or bromine
• a cyano group such as a chloromethyl group, a 2-bromoethyl group, a 3-chloropropyl group
• Typical ones have 1 to 10 carbon atoms, particularly typical ones have 1 to 6 carbon atoms, preferably methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms such as 3,3,3-trifluoropropyl group and cyanoethyl group; unsubstituted or substituted phenyl groups such as phenyl group, chlorophenyl group and fluorophenyl group; and It is an alkoxy group such as a methoxy group. Moreover, it is not limited that all the functional groups other than the alkenyl group bonded to the silicon atom are the same.
• the alkenyl group-containing organopolysiloxane (a-1) has a kinematic viscosity at 25° C. of preferably 10 to 100,000 mm 2 /s, more preferably 40 to 50,000 mm 2 /s, still more preferably 50 to 10, 000 mm 2 /s, more preferably 60 to 5,000 mm 2 /s, and even more preferably 80 to 1,000 mm 2 /s.
• the thermally conductive powder (B) can be highly filled, and when it is 100,000 mm 2 /s or less, an increase in the viscosity of the thermally conductive composition can be suppressed.
• kinematic viscosity can be measured by an Ostwald viscometer, and specifically by the method described in Examples.
• Organopolysiloxane (a-2) having a hydrosilyl group examples include organohydrogenpolysiloxanes having two or more hydrogen atoms directly bonded to silicon atoms.
• the organohydrogenpolysiloxane preferably has 2 to 100 hydrogen atoms (Si—H groups) directly bonded to silicon atoms in one molecule, and the alkenyl group-containing organopolysiloxane (a-1) Acts as a cross-linking agent.
• the organohydrogenpolysiloxane is preferably represented by the following general formula (I).
• each R1 is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond or a hydrogen atom. However, at least two are hydrogen atoms.
• g is an integer of 0 or more.
• examples of the unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond other than a hydrogen atom for R include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group.
• non-carbon atoms having 1 to 3 such as methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3,3,3-trifluoropropyl group, cyanoethyl group, etc.
• Preferred are substituted or substituted alkyl groups and unsubstituted or substituted phenyl groups such as phenyl, chlorophenyl and fluorophenyl groups.
• R1 is not limited to being the same except for hydrogen atoms.
• At least 2, preferably 2 to 100, more preferably 2 to 50 of R1 are hydrogen atoms, and the hydrogen atoms are either at the molecular chain terminal or the molecular chain non-terminal (i.e., molecular chain side chain) or both.
• the organohydrogenpolysiloxane has a kinematic viscosity at 25° C. of preferably 10 to 100,000 mm 2 /s, more preferably 15 to 10,000 mm 2 /s, still more preferably 20 to 1,000 mm 2 /s, Even more preferably, it is 25 to 500 mm 2 /s.
• the thermally conductive powder (B) can be highly filled, and when it is 100,000 mm 2 /s or less, an increase in the viscosity of the thermally conductive composition can be suppressed. .
• the molar amount of hydrogen atoms directly bonded to silicon atoms in the organohydrogenpolysiloxane is preferably from 0.05 to 1 mol of alkenyl groups bonded to silicon atoms in the alkenyl group-containing organopolysiloxane (a-1). It is 1.5 mol, more preferably 0.08 to 1.3 mol, still more preferably 0.1 to 1.0 mol.
• the molar amount of the hydrogen atoms is 0.05 mol or more, the cured product of the thermally conductive composition does not become too soft and is easy to handle. Adhesion to objects becomes good, and thermal conductivity can be improved.
• the platinum group metal-based curing catalyst (a-3) comprises an alkenyl group in the alkenyl group-containing organopolysiloxane (a-1) and a Si—H group in the hydrosilyl group-containing organopolysiloxane (a-2). promotes the addition reaction with and gives a three-dimensional network structure having a crosslinked structure.
• platinum group metal-based curing catalyst (a-3) examples include catalysts known as catalysts used in hydrosilylation reactions. Specific examples thereof include, for example, platinum (including platinum black), rhodium, palladium and other platinum group metal simple substances, H 2 PtCl 4 ⁇ nH 2 O, H 2 PtCl 6 ⁇ nH 2 O, NaHPtCl 6 ⁇ nH 2 O , KaHPtCl6.nH2O , Na2PtCl6.nH2O , K2PtCl4.nH2O , PtCl4.nH2O , PtCl2 , Na2HPtCl4.nH2O ( wherein , n is an integer of 0 to 6, preferably 0 or 6); ), a complex of chloroplatinic acid and an olefin (see U.S.
• Pat. Nos. 3,159,601, 3,159,662 and 3,775,452 platinum black
• a platinum group metal such as palladium supported on a carrier such as alumina, silica, carbon, etc., rhodium-olefin complex, chlorotris(triphenylphosphine) rhodium (Wilkinson's catalyst), platinum chloride, chloroplatinic acid or chloroplatinate and a vinyl group-containing siloxane, particularly a vinyl group-containing cyclic siloxane.
• the amount of the platinum group metal curing catalyst (a-3) added is the platinum group metal element relative to the total content of the alkenyl group-containing organopolysiloxane (a-1) and the hydrosilyl group-containing organopolysiloxane (a-2). In terms of mass, it is preferably 0.1 to 1000 ppm, more preferably 1 to 700 ppm, still more preferably 5 to 500 ppm.
• the alkenyl group in the alkenyl group-containing organopolysiloxane (a-1) and the hydrosilyl group-containing organopolysiloxane (a -2) can promote the addition reaction with the Si—H groups in.
• addition reaction-curable silicone resin Commercially available products can also be used as the addition reaction-curable silicone resin.
• Commercially available products of the addition reaction curing type silicone resin include, for example, DOWSIL TM EG-3100 (manufactured by Dow Toray Industries, Inc.).
• the thermal conductive composition of the present embodiment may further contain an addition reaction controller (a-4).
• an addition reaction controller (a-4) known addition reaction controllers used for ordinary addition reaction curing silicone resins can be used. Examples include acetylene compounds such as 1-ethynyl-1-hexanol and 3-butyn-1-ol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, organic chloro compounds, and the like.
• the addition amount of the addition reaction controller (a-4) is determined, from the viewpoint of ensuring working time during use, of the alkenyl group-containing organopolysiloxane (a-1) and the hydrosilyl group-containing organopolysiloxane (a-2). It is preferably 0.001 to 5% by mass, more preferably 0.005 to 4% by mass, and still more preferably 0.01 to 3% by mass relative to the total content.
• the content of the curable silicone resin (A) is preferably 1.0 to 30% by mass, more preferably 1.5 to 20% by mass, and still more preferably 2.0 to 10% by mass.
• the content of the curable silicone resin (A) is 1.0% by mass or more, the viscosity of the thermal conductive composition does not become too high, and workability is improved. Improves conductivity.
• the thermally conductive powder (B) used in the present embodiment contains 30 aluminum nitride particles (B-1) having a cumulative volume 50% particle size of 50 ⁇ m or more and 150 ⁇ m or less with respect to the total amount of the thermally conductive powder (B).
• the metal oxide (B-3) other than zinc oxide and the zinc oxide (B-4) are both a silane coupling agent having an alkyl group having 10 to 22 carbon atoms and ⁇ -butyl- ⁇ -( 2-trimethoxysilylethyl)polydimethylsiloxane, and is surface-treated with at least one surface-treating agent selected from the group consisting of polydimethylsiloxane.
• the thermally conductive powder (B) comprises the aluminum nitride particles (B-1), the aluminum nitride particles (B-2), the metal oxide other than zinc oxide (B-3), and the zinc oxide (B- By including 4) within the above ranges, both high heat transfer performance and good fluidity can be achieved.
• the aluminum nitride particles (B-1) used in the present embodiment have a cumulative volume 50% particle size of 50 ⁇ m or more and 150 ⁇ m or less, preferably 55 ⁇ m or more and 140 ⁇ m or less, more preferably 60 ⁇ m or more and 130 ⁇ m or less, and further The thickness is preferably 60 ⁇ m or more and 100 ⁇ m or less, and more preferably 60 ⁇ m or more and 80 ⁇ m or less.
• the cumulative volume 50% particle size (hereinafter sometimes referred to as D50) is the particle size at which the cumulative volume is 50% in the particle size distribution measured using a laser diffraction particle size distribution analyzer. can be obtained from
• the aluminum nitride particles (B-1) are not particularly limited as long as they satisfy the particle size of 50% of the cumulative volume, and known products such as commercially available products can be used.
• the aluminum nitride particles (B-1) may be obtained by any method. It may be obtained by a reductive nitriding method in which heating is performed in an atmosphere and a nitriding reaction is performed simultaneously.
• the aluminum nitride particles (B-1) may be a sintered body or a non-sintered body, and are preferably a sintered body from the viewpoint of high filling.
• the shape is not particularly limited, and examples thereof include amorphous (crushed), spherical, elliptical, and plate-like (scale-like). Among them, a spherical shape is preferable from the viewpoint of ensuring the fluidity of the heat conductive composition.
• the term “sintered body” refers to a product obtained by adding a sintering aid or a particle size control agent to aluminum nitride particles, sintering them at high temperature, and then pulverizing or classifying them.
• spherical refers to a particle state that is a true sphere or has a rounded shape without substantially corners
• crushed refers to a particle state that has an arbitrary shape with corners that crushed particles have. Anything that can be identified by an electron microscope or other microscope.
• the BET specific surface area of the aluminum nitride particles (B-1) is preferably 0.01 to 1.0 m 2 /g, more preferably 0.01 to 1.0 m 2 /g, from the viewpoint of filling properties into the curable silicone resin (A). 02 to 0.8 m 2 /g, more preferably 0.03 to 0.5 m 2 /g.
• the BET specific surface area can be measured by a nitrogen adsorption BET single-point method using a gas flow method, and specifically by the method described in Examples.
• the content of the aluminum nitride particles (B-1) is 30 to 75% by mass, preferably 32 to 60% by mass, more preferably 35 to 55% by mass with respect to the total amount of the thermally conductive powder (B). % by mass.
• the content of the aluminum nitride particles (B-1) is 30% by mass or more, the thermal conductivity can be improved, and when it is 75% by mass or less, the fluidity and ease of handling of the heat conductive composition can be secured. be able to.
• the aluminum nitride particles (B-2) used in the present embodiment have a cumulative volume 50% particle size of 15 ⁇ m or more and less than 50 ⁇ m, preferably 17 ⁇ m or more and 45 ⁇ m or less, more preferably 20 ⁇ m or more and 40 ⁇ m or less. It is preferably 30 ⁇ m or more and 40 ⁇ m or less.
• the 50% cumulative volume particle size of the aluminum nitride particles (B-2) is within the above range, both high thermal conductivity performance and good fluidity of the composition can be achieved.
• the aluminum nitride particles (B-2) are not particularly limited as long as they satisfy the particle diameter of 50% of the cumulative volume, and may be a sintered body or a non-sintered body.
• the aluminum nitride particles (B-2) are preferably non-sintered crushed aluminum nitride particles from the viewpoint of high thermal conductivity.
• the BET specific surface area of the aluminum nitride particles (B-2) is preferably 0.01 to 1.0 m 2 /g, more preferably 0.01 to 1.0 m 2 /g, from the viewpoint of filling properties into the curable silicone resin (A).
• the method for measuring the BET specific surface area of the aluminum nitride particles (B-2) is as described for the aluminum nitride particles (B-1).
• the content of the aluminum nitride particles (B-2) is 10 to 30% by mass, preferably 10 to 25% by mass, more preferably 15 to 20% with respect to the total amount of the thermally conductive powder (B). % by mass.
• the content of the aluminum nitride particles (B-2) is 10% by mass or more, the thermal conductivity can be improved, and when it is 30% by mass or less, the fluidity and ease of handling of the heat conductive composition can be secured. be able to.
• At least one kind of aluminum nitride particles selected from the group consisting of the aluminum nitride particles (B-1) and the aluminum nitride particles (B-2) has a silicon-containing oxide film on its surface, which improves moisture resistance. preferable from this point of view.
• the silicon-containing oxide film may cover part or all of the surface of the aluminum nitride particles, but preferably covers the entire surface of the aluminum nitride particles. Since aluminum nitride particles have excellent thermal conductivity, aluminum nitride particles having a silicon-containing oxide film on their surfaces (hereinafter also referred to as silicon-containing oxide-coated aluminum nitride particles) also have excellent thermal conductivity.
• the "silicon-containing oxide" of the silicon-containing oxide coating and silicon-containing oxide-coated aluminum nitride particles includes silica and oxides containing silicon and aluminum.
• the silicon-containing oxide-coated aluminum nitride particles preferably have a coverage of 70% or more and 100% or less, more preferably 70% or more and 95% or less, according to LEIS analysis of the silicon-containing oxide film covering the surface of the aluminum nitride particles. , more preferably 72% or more and 90% or less, and particularly preferably 74% or more and 85% or less.
• coverage 70% or more and 100% or less, the moisture resistance is more excellent.
• it exceeds 95% the thermal conductivity may decrease.
• the coverage (%) by LEIS (Low Energy Ion Scattering) analysis of the silicon-containing oxide film (SiO 2 ) covering the surface of the aluminum nitride particles is determined by the following formula. (S Al (AlN) ⁇ S Al (AlN+SiO 2 ))/S Al (AlN) ⁇ 100
• S Al (AlN) is the Al peak area of the aluminum nitride particles
• S Al (AlN+SiO 2 ) is the Al peak area of the silicon-containing oxide-coated aluminum nitride particles.
• the Al peak area can be obtained from analysis by low energy ion scattering (LEIS), which is a measurement method using an ion source and a noble gas as probes.
• LEIS is an analysis technique that uses incident ions of a rare gas of several keV, and is an evaluation technique that enables composition analysis of the outermost surface (Reference: The TRC News 201610-04 (October 2016)).
• a method for forming a silicon-containing oxide film on the surface of aluminum nitride particles includes, for example, a first step of covering the surface of aluminum nitride particles with a siloxane compound containing a structure represented by the following formula (1); and a second step of heating the aluminum nitride particles coated with the above at a temperature of 300° C. or higher and 800° C. or lower.
• R is an alkyl group having 4 or less carbon atoms.
• R is an alkyl group having 4 or less carbon atoms, that is, a methyl group, an ethyl group, a propyl group or a butyl group, preferably a methyl group, an ethyl group, an isopropyl group or a t-butyl group. , and more preferably a methyl group.
• the siloxane compound is preferably an oligomer or polymer containing the structure represented by formula (1) as a repeating unit. Moreover, the siloxane compound may be linear, branched or cyclic.
• the weight-average molecular weight of the siloxane compound is preferably 100 to 2000, more preferably 150 to 1000, and still more preferably 180 to 500, from the viewpoint of ease of forming a silicon-containing oxide film having a uniform thickness. is. In addition, let the said weight average molecular weight be a polystyrene conversion value by a gel permeation chromatography (GPC).
• siloxane compound a compound represented by the following formula (2) and/or a compound represented by the following formula (3) is preferably used.
• R2 and R3 are each independently a hydrogen atom or a methyl group, and at least one of R2 and R3 is a hydrogen atom.
• m is an integer of 0-10, preferably 1-5, more preferably 1;
• n is an integer of 3-6, preferably 3-5, more preferably 4.
• siloxane compound a cyclic hydrogensiloxane oligomer in which n is 4 in formula (3) is particularly preferable from the viewpoint of facilitating the formation of a good silicon-containing oxide film.
• the surfaces of the aluminum nitride particles are covered with a siloxane compound containing the structure represented by the formula (1).
• the method is not particularly limited as long as the surfaces of the aluminum nitride particles can be covered with the siloxane compound containing the structure represented by the formula (1).
• the siloxane compound is added by spraying or the like while stirring the raw material aluminum nitride particles, and dry mixing is performed to coat. is mentioned.
• Examples of the powder mixing device include a Henschel mixer (manufactured by Nippon Coke Industry Co., Ltd.), a container rotating V blender, a double cone blender, a ribbon blender having mixing blades, a screw blender, a closed rotary kiln, Stirring by means of a stirrer in a closed vessel using magnetic coupling can be mentioned.
• the temperature conditions are not particularly limited, but are preferably 10° C. or higher and 200° C. or lower, more preferably 20° C. or higher and 150° C. or lower, and still more preferably 40° C. or higher and 100° C. or lower.
• a gas phase adsorption method can also be used in which the vapor of the siloxane compound alone or a mixed gas with an inert gas such as nitrogen gas is attached or deposited on the surface of the aluminum nitride particles left still.
• the temperature conditions are not particularly limited, but are preferably 10° C. or higher and 200° C. or lower, more preferably 20° C. or higher and 150° C. or lower, and still more preferably 40° C. or higher and 100° C. or lower.
• the inside of the system can be pressurized or decompressed.
• a closed system and an apparatus that can easily replace the gas in the system are preferable.
• the amount of the siloxane compound used in the first step is not particularly limited.
• the coating amount of the siloxane compound is a surface area of 1 m 2 calculated from the specific surface area (m 2 /g) obtained by the BET method of the aluminum nitride particles. It is preferably 0.1 mg or more and 1.0 mg or less, more preferably 0.2 mg or more and 0.8 mg or less, and still more preferably 0.3 mg or more and 0.6 mg or less.
• the coating amount of the siloxane compound is within the above range, aluminum nitride particles having a silicon-containing oxide coating with a uniform thickness can be obtained.
• the coating amount of the siloxane compound per 1 m 2 of the surface area calculated from the specific surface area (m 2 /g) obtained by the BET method of the aluminum nitride particles is the mass difference between the aluminum nitride particles before and after coating with the siloxane compound. can be obtained by dividing by the surface area (m 2 ) calculated from the specific surface area (m 2 / g) obtained by the BET method of the aluminum nitride particles.
• the aluminum nitride particles coated with the siloxane compound obtained in the first step are heated at a temperature of 300°C or higher and 800°C or lower. Thereby, a silicon-containing oxide film can be formed on the surface of the aluminum nitride particles.
• the heating temperature is more preferably 400° C. or higher, still more preferably 500° C. or higher.
• the heating time is preferably 30 minutes or more and 6 hours or less, more preferably 45 minutes or more and 4 hours or less, from the viewpoint of ensuring a sufficient reaction time and efficiently forming a good silicon-containing oxide film. More preferably 1 hour or more and 2 hours or less.
• the atmosphere during the heat treatment is preferably an atmosphere containing oxygen gas, for example, the atmosphere (air).
• the silicon-containing oxide-coated aluminum nitride particles may partially fuse together.
• silicon-containing oxide-coated aluminum nitride particles free from sticking and agglomeration can be obtained.
• the first step and the second step may be performed in order. That is, the step of sequentially performing the first step and the second step may be repeatedly performed.
• the metal oxide (B-3) other than zinc oxide used in the present embodiment has a cumulative volume 50% particle size of 1 ⁇ m or more and less than 20 ⁇ m, preferably 2 ⁇ m or more and 15 ⁇ m or less, more preferably 3 ⁇ m or more and 10 ⁇ m or less. and more preferably 3 ⁇ m or more and 6 ⁇ m or less.
• the 50% cumulative volume particle diameter of the metal oxide (B-3) other than zinc oxide is within the above range, the fluidity and ease of handling of the heat conductive composition can be ensured.
• the metal oxide (B-3) other than zinc oxide is a silane coupling agent having an alkyl group having 10 to 22 carbon atoms (hereinafter also simply referred to as a silane coupling agent) and ⁇ -butyl- ⁇ -(2- trimethoxysilylethyl) polydimethylsiloxane surface-treated with at least one surface treatment agent selected from the group consisting of polydimethylsiloxane.
• the alkyl group of the silane coupling agent preferably has 12 to 20 carbon atoms, more preferably 16 to 18 carbon atoms.
• the fluidity of the thermally conductive composition and the fillability of the thermally conductive powder can be enhanced.
• the silane coupling agent include decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, hexadecyltrimethoxysilane, heptadecyltrimethoxysilane, octadecyltrimethoxysilane, icosyltrimethoxysilane, and the like. mentioned.
• decyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane are preferable, and hexadecyltrimethoxysilane is more preferable, from the viewpoint of enhancing the fluidity of the heat conductive composition.
• the silane coupling agents may be used alone or in combination of two or more.
• the repeating unit of dimethylsiloxane is an integer of 5-200, preferably 10-100, more preferably 12-50.
• the fluidity of the heat conductive composition is improved, and when it is 200 or less, the viscosity of ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane increases. It does not become too high, and the fluidity of the heat conductive composition becomes good.
• the solubility in a solvent is improved when the metal oxide (B-3) other than zinc oxide and the zinc oxide (B-4) described later are subjected to surface treatment, and the preparation of the hydrolysis solution is facilitated.
• the amounts of the silane coupling agent and ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane used are each preferably 0.00 to the total amount of the metal oxide (B-3) other than zinc oxide. It is 1 to 10% by mass, more preferably 0.2 to 8% by mass, and still more preferably 0.2 to 6% by mass.
• Surface treatment of the metal oxide (B-3) other than zinc oxide by using the silane coupling agent and ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane within the above ranges, respectively. can be done sufficiently.
• the surface treatment method of the metal oxide (B-3) other than zinc oxide with the silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane includes a dry method, a wet method, There is an integral blend method and the like, and any method may be used.
• a predetermined amount of silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane as it is or a solution diluted with an organic solvent is mixed with a metal oxide other than zinc oxide (B- 3) by mechanically mixing while spraying or dropping into, and then drying and baking of a silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane as necessary. is the way to do it.
• a metal oxide (B-3) other than zinc oxide is added to a solution obtained by diluting a predetermined amount of a silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane with an organic solvent. It is a method of impregnating, stirring and mixing, and volatilizing the solvent.
• a predetermined amount of a silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxy silylethyl) polydimethylsiloxane is a predetermined amount of a silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxy silylethyl) polydimethylsiloxane.
• the surface treatment apparatus includes a rotation/revolution stirring mixer, a blender, a Nauta, a Henschel mixer, a planetary mixer, and the like, and any of them may be used.
• the heat treatment is preferably performed for up to 12 hours, more preferably at a temperature of 110 to 150° C. for 1 to 8 hours, and even more preferably at a temperature of 110 to 130° C. for 2 to 4 hours.
• the metal oxide (B-3) other than zinc oxide is surface-treated with the surface treatment agent described above, and is not particularly limited as long as it satisfies the cumulative volume 50% particle diameter.
• Examples include alumina (aluminum oxide), Examples include magnesium oxide, silicon dioxide, and iron oxide. Among them, alumina is preferable from the viewpoint of high thermal conductivity.
• Alumina has thermal conductivity and excellent moisture resistance.
• Alumina is preferably ⁇ -alumina ( ⁇ -Al 2 O 3 ).
• ⁇ -alumina ⁇ -alumina
• ⁇ -alumina ⁇ -alumina
• ⁇ -alumina ⁇ -alumina
• ⁇ -alumina ⁇ -alumina
• ⁇ -alumina ⁇ -alumina
• ⁇ -alumina ⁇ -alumina
• ⁇ -alumina ⁇ -alumina
• Alumina can use well-known things, such as a commercial item.
• Alumina may be produced by any method, for example, thermal decomposition of ammonium alum, thermal decomposition of ammonium aluminum carbonate, underwater spark discharge of aluminum, vapor phase oxidation, and aluminum alkoxide. obtained by a hydrolysis method or the like.
• the shape of alumina is not particularly limited, and examples thereof include amorphous (crushed), spherical, rounded, and polyhedral.
• the BET specific surface area of the metal oxide (B-3) other than zinc oxide is preferably 0.05 to 2.0 m 2 /g from the viewpoint of filling the curable silicone resin (A). It is preferably 0.1 to 1.5 m 2 /g, more preferably 0.2 to 1.0 m 2 /g.
• the method for measuring the BET specific surface area of the metal oxide (B-3) other than zinc oxide is as described for the aluminum nitride particles (B-1).
• the content of the metal oxide (B-3) other than zinc oxide is 5 to 15% by mass, preferably 6 to 15% by mass, more preferably 6 to 15% by mass, based on the total amount of the thermally conductive powder (B). is 8 to 14% by mass.
• the content of the metal oxide (B-3) other than zinc oxide is within the above range, the fluidity and ease of handling of the heat conductive composition can be ensured.
• the zinc oxide (B-4) used in the present embodiment has a 50% cumulative volume particle size of 0.1 ⁇ m or more and less than 1 ⁇ m, and a BET specific surface area of less than 9.0 m 2 /g.
• the 50% cumulative volume particle size of the zinc oxide (B-4) is within the above range, the fluidity and ease of handling of the heat conductive composition can be ensured.
• the 50% cumulative volume particle size of the zinc oxide (B-4) is preferably 0.2 ⁇ m or more and 0.9 ⁇ m or less, more preferably 0.3 ⁇ m or more and 0.8 ⁇ m or less.
• the BET specific surface area of the zinc oxide (B-4) is preferably 8.0 m 2 /g or less, more preferably 7.0 m 2 /g or less, and still more preferably 6.0 m 2 /g or less. It is 0 m 2 /g or less, more preferably 5.8 m 2 /g or less, and even more preferably 5.5 m 2 /g or less.
• the lower limit of the BET specific surface area of the zinc oxide (B-4) is not particularly limited, it is preferably 1.0 m 2 /g or more.
• the method for measuring the BET specific surface area of zinc oxide (B-4) is as described for the aluminum nitride particles (B-1), and specifically, it can be measured by the method described in Examples. .
• the zinc oxide (B-4) is at least one selected from the group consisting of a silane coupling agent having an alkyl group having 10 to 22 carbon atoms and ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane. It is surface-treated with a surface treatment agent. By surface-treating the zinc oxide (B-4) with the surface-treating agent, the fluidity of the heat-conducting composition can be enhanced.
• the preferred number of carbon atoms in the alkyl group of the silane coupling agent is as described for the metal oxide other than zinc oxide (B-3).
• silane coupling agent or ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane those exemplified for the metal oxide (B-3) other than zinc oxide can be used.
• metal oxides other than zinc oxide (B -3) metal oxides other than zinc oxide (B -3) can be mentioned.
• the amounts of the silane coupling agent and ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane used are each preferably 0.1 to 10% by mass relative to the total amount of zinc oxide (B-4). , more preferably 0.2 to 8% by mass, still more preferably 0.2 to 6% by mass.
• the zinc oxide (B-4) is sufficiently surface-treated by using the silane coupling agent and ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane within the respective ranges. can be done.
• the content of the zinc oxide (B-4) is 10 to 40% by mass, preferably 15 to 38% by mass, more preferably 20 to 35% by mass with respect to the total amount of the thermally conductive powder (B). %.
• the content of the zinc oxide (B-4) is 10% by mass or more, the fluidity of the thermally conductive composition can be enhanced, and when it is 40% by mass or less, a decrease in thermal conductivity can be suppressed.
• the thermally conductive powder (B) includes the aluminum nitride particles (B-1), the aluminum nitride particles (B-2), the metal oxide other than zinc oxide (B-3), and the zinc oxide (B It may contain thermally conductive powder (b) other than -4).
• Examples of the thermally conductive powder (b) include metal oxides (excluding zinc oxide (B-3) and zinc oxide (B-4)), metal nitrides (aluminum nitride particles (B-1 ), aluminum nitride particles (B-2) excluded), metal hydroxides, and the like.
• Metal nitrides include boron nitride, aluminum nitride, silicon nitride, and the like.
• Metal oxides include zinc oxide, alumina, magnesium oxide, silicon dioxide, iron oxide and the like.
• metal hydroxides include aluminum hydroxide and magnesium hydroxide.
• the content of the thermally conductive powder (B) is 70 to 98% by mass, preferably 80 to 98% by mass, more preferably 85 to 98% by mass, relative to the total amount of the thermally conductive composition. , More preferably 90 to 98% by mass, still more preferably 95 to 97% by mass.
• the content of the thermally conductive powder (B) is 70% by mass or more, sufficient thermal conductivity performance can be ensured, and when it is 98% by mass or less, the fluidity of the thermally conductive composition is good, and the discharge can be made easier.
• the thermally conductive composition of the present embodiment preferably further contains dimethylsilicone oil (C) from the viewpoint of further reducing the viscosity of the thermally conductive composition.
• the dimethylsilicone oil (C) is an organopolysiloxane having no curable functional group and is a non-reactive silicone oil.
• the dimethyl silicone oil (C) has a kinematic viscosity at 25° C. of preferably 10 to 100,000 mm 2 /s, more preferably 20 to 10,000 mm 2 /s, still more preferably 30 to 1,000 mm 2 /s. , more preferably 40 to 500 mm 2 /s, still more preferably 40 to 200 mm 2 /s.
• the thermally conductive powder (B) can be highly filled, and when it is 100,000 mm 2 /s or less, an increase in the viscosity of the thermally conductive composition can be suppressed.
• the kinematic viscosity can be measured with an Ostwald viscometer as described above.
• the content of the dimethyl silicone oil (C) is preferably 0.1 to 2.0% by mass, more preferably 0.2 to 1.8% by mass, based on the total amount of the heat conductive composition, and further It is preferably 0.3 to 1.5% by mass.
• the content of the dimethyl silicone oil (C) is 0.1% by mass or more, the viscosity of the heat conductive composition can be further reduced, and when it is 2.0% by mass or less, bleeding of the dimethyl silicone oil is suppressed. be able to.
• the thermally conductive composition of the present embodiment contains additives such as flexibility-imparting agents, inorganic ion scavengers, pigments, dyes, and diluents within a range that does not impede the effects of the present invention. They can be blended as needed.
• the total content of the curable silicone resin (A) and the heat conductive powder (B) is preferably 85% by mass or more from the viewpoint of improving heat conductivity, and more It is preferably 90% by mass or more, more preferably 95% by mass or more.
• the thermally conductive composition of the present embodiment comprises the curable silicone resin (A), the thermally conductive powder (B), and an addition reaction control agent (a-4) blended as necessary, dimethyl silicone oil (C ), and various additives in batches or in portions, supplied to a dispersing/dissolving apparatus, and mixed, dissolved, and kneaded while being heated as necessary.
• the dispersing/dissolving apparatus includes, for example, a scouring vessel, a planetary mixer, a rotation/revolution mixer, a kneader, a roll mill, and the like.
• the thermally conductive composition of the present embodiment has a viscosity at 25° C. of preferably 50,000 Pa ⁇ s or less, more preferably 45,000 Pa ⁇ s or less, and still more preferably 40,000 a ⁇ s or less.
• the lower limit of the viscosity is preferably 50 Pa ⁇ s or more, more preferably 100 Pa ⁇ s or more, still more preferably 150 Pa ⁇ s or more.
• the viscosity can be measured by a method conforming to JIS K7210:2014 using a flow viscometer, and specifically by the method described in Examples.
• Methods for curing the thermally conductive composition of the present embodiment include, for example, a method in which the composition is applied to an adherend that requires heat dissipation, and then the composition is left at room temperature (23° C.); method.
• the heating is preferably performed at a temperature of 50° C. to 150° C. for 5 minutes to 10 hours, more preferably at a temperature of 60° C. to 130° C. for 10 minutes to 5 hours. . From the viewpoint of rapid curing, it is preferable to employ a heating method.
• the cured product of the thermally conductive composition of the present embodiment preferably has a thermal conductivity of 10.0 W/m ⁇ K or more, more preferably 10.5 W/m ⁇ K or more.
• the thermal conductivity can be measured by a method conforming to ISO22007-2, and specifically by the method described in Examples.
• the cured product of the thermally conductive composition of the present embodiment preferably has a C hardness of 15 to 95, more preferably 18 to 90, measured according to the hardness test (type C) of JIS K7312:1996. Yes, more preferably 20-85, still more preferably 20-80.
• the C hardness can be specifically measured by the method described in Examples.
• the thermally conductive composition of the present embodiment can achieve both high thermal conductivity and good fluidity. It can be suitably used as a heat radiating member such as an adhesive.
• a siloxane compound cyclic methylhydrogensiloxane tetramer: manufactured by Tokyo Kasei Kogyo Co., Ltd.
• the vacuum desiccator was closed and heating was performed in an oven at 80° C. for 8 hours.
• the hydrogen gas generated by the reaction was operated while taking safety measures such as letting it escape from an open valve attached to the vacuum desiccator.
• the sample was taken out from the desiccator and placed in an alumina crucible, and the sample was subjected to heat treatment in the second step at 850 ° C. for 6 hours in the air, thereby nitriding the silicon-containing oxide coating.
• Aluminum particles (B-1) were obtained.
• the amount of hexadecyltrimethoxysilane calculated by the following formula (i) was Add 1/3 of the corresponding hydrolyzate-1 with a dropper, and stir and mix for 20 seconds at a rotation speed of 2000 rpm with a rotation/revolution mixer (ARE-310, manufactured by Thinky Co., Ltd.), and repeat this three times. repeated.
• the resulting mixture was placed in a stainless vat and heat-treated in a hot air oven at 120° C. for 2 hours to obtain alumina (B-3a) surface-treated with hexadecyltrimethoxysilane.
• the resulting zinc oxide had a D50 of 0.5 ⁇ m and a BET specific surface area of 4.1 m 2 /g.
• B-4a hydrolyzate-1 Zinc oxide
• ARE-310 manufactured by THINKY Co., Ltd.
• the resulting mixture was placed in a stainless vat and heat-treated in a hot air oven at a temperature of 120° C. for 2 hours to obtain an alumina surface-treated with ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane ( B-3c) was obtained.
• Zinc oxide surface treatment Zinc oxide surface treatment
• Zinc oxide- 2 surface-treated with ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethylsiloxane was obtained in the same manner as surface treatment 7, except that 100 g of Zinc Oxide 2/g) was used.
• hydrolyzate-8 In order to grind 500 g of zinc oxide JIS type 1 (manufactured by Hakusui Tech Co., Ltd.) with a ball mill, it was placed in a 5 L PE container together with 5 kg of alumina balls with a diameter of 10 mm, and rotated at a rotation speed of 90 rpm for 3 hours to grind the zinc oxide. .
• the resulting zinc oxide had a D50 of 0.5 ⁇ m and a BET specific surface area of 4.1 m 2 /g.
• hydrolyzate-2 Zinc oxide-3 surface-treated with n-propyltrimethoxysilane was obtained in the same manner as surface treatment 2, except that hydrolyzate-8 was used.
• Examples 1 to 7 and Comparative Examples 1 to 6) (1) Preparation of heat-conducting composition Each component of the type and blending amount shown in Tables 1 and 2 was weighed into a polyethylene container, put into a rotation/revolution mixer (manufactured by Thinky Co., Ltd.), and rotated at 2000 rpm. , for 90 seconds. After cooling, the mixture was loosened, and further stirred and mixed with a rotation/revolution mixer at a rotation speed of 2000 rpm for 90 seconds to obtain a heat conductive composition of each example and comparative example. In Comparative Example 6, even if each component of the type and blending amount shown in Table 2 was mixed, it was in a powder state and could not be formed into a sheet, and each evaluation described later could not be performed.
• the kinematic viscosity at 25 ° C. of the organopolysiloxane (a-1) having an alkenyl group, the organopolysiloxane (a-2) having a hydrosilyl group, and the dimethyl silicone oil (C) was measured using an Ostwald viscometer (Shibata Science Co., Ltd.) (manufactured).
• the cumulative volume 50% particle size (D50) and BET specific surface area of the thermally conductive powder (B) were measured by the following measuring methods.
• the particle size was obtained from the particle size at which the cumulative volume is 50% in the particle size distribution measured using a laser diffraction particle size distribution analyzer (manufactured by Microtrack Bell Co., Ltd., trade name: MT3300EXII).
• Asker C Hardness The obtained sheet with a thickness of 2.0 mm was cut into strips of 20 mm in width and 30 mm in length. Using an Asker C hardness tester (Asker C rubber hardness tester, manufactured by Kobunshi Keiki Co., Ltd.), the Asker C hardness of the measurement sample was measured according to JIS K7312:1996 hardness test (type C).
• Viscosity In accordance with JIS K7210: 2014, using a flow viscometer (GFT-100EX, manufactured by Shimadzu Corporation), temperature 30 ° C., die hole diameter (diameter) 1.0 mm, test force 10 ( It was measured under the condition of a weight of 1.8 kg).
• thermally conductive powder (B) aluminum nitride particles (B-1), aluminum nitride particles (B-2), metal oxides other than zinc oxide (B-3), and zinc oxide
• the thermal conductive compositions of Examples 1 to 7 containing (B-4) all have a low viscosity of 50000 Pa s or less at 25 ° C., and the thermal conductivity of the cured product is 10.0 W / m K. As described above, it can be seen that both high heat transfer performance and good fluidity can be achieved.
• the cured products of the thermally conductive compositions of Examples 1 to 7 have an Asker C hardness of 20 to 55, which is an appropriate degree of hardness.
• the thermally conductive compositions of Comparative Examples 1 and 2 which do not contain zinc oxide (B-4) as the thermally conductive powder (B) and contain alumina having a particle size of less than 1 ⁇ m at 50% of the cumulative volume, are thermally conductive. Although the modulus is high, the viscosity at 25°C is very high at 94,000 Pa ⁇ s and 95,000 Pa ⁇ s. Further, as the thermally conductive powder (B), zinc oxide having a BET specific surface area of 9.0 m 2 /g and surface-treated with hexadecyltrimethoxysilane was used instead of zinc oxide (B-4). The thermally conductive composition of Example 3 has a very high viscosity of 200000 Pa ⁇ s at 25°C.
• thermally conductive powder (B) instead of zinc oxide (B-4), it has a BET specific surface area of 9.0 m 2 /g, ⁇ -butyl- ⁇ -(2-trimethoxysilylethyl)polydimethyl
• the thermally conductive composition of Comparative Example 4 containing zinc oxide surface-treated with siloxane has a low viscosity at 25° C., but a low thermal conductivity of 9.5 W/m ⁇ K.
• the thermally conductive composition of Comparative Example 5 containing zinc oxide surface-treated with n-propyltrimethoxysilane instead of zinc oxide (B-4) was too hard.
• Comparative Example 6 which contained zinc oxide that was not surface-treated instead of zinc oxide (B-4) as the thermally conductive powder (B), the state after mixing of each component was powdery and formed into a sheet. could not.

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