Thermally conductive addition-curable silicone composition and its cured product

Abstract

To provide a thermally conductive addition-curable silicone composition having excellent heat-dissipation properties.SOLUTION: There is provided a thermally conductive addition-curable silicone composition which comprises (A) an organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and a kinematic viscosity at 25°C of 60 to 100000 mm2 / s, (B) a phenol compound: in an amount of 0.01 to 10 mass% based on the total composition, (C) a silver powder: in an amount of 10 to 98 mass% based on the total composition, (D) an organohydrogen polysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule: in an effective amount sufficient for the composition to form a cured product and (E) a platinum group metal catalyst: in an effective amount.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermally conductive addition-curable silicone composition and a cured product thereof. [Background technology]

[0002] A common problem with electronic component packages and power modules is the generation of heat during operation and the resulting degradation of performance, and various heat dissipation technologies are used to solve this problem. In particular, a common technology is to dissipate heat by placing a cooling member near the heat-generating part and bringing them into close contact with each other, and then efficiently removing heat from the cooling member.

[0003] In this case, if there is a gap between the heat generating part and the cooling member, the air with poor thermal conductivity will be interposed, reducing the heat transfer and preventing the temperature of the heat generating member from dropping sufficiently. In order to prevent the interposition of such air and improve the heat conduction, heat dissipation materials with good thermal conductivity and conformability to the surface of the member, such as heat dissipation grease and heat dissipation sheets, are used (for example, Patent Documents 1 to 9).

[0004] As a heat countermeasure for actual electronic component packages and power modules, heat dissipation grease that can be compressed thin and has excellent penetration into the gap between the heat generating part and the cooling member is suitable from the viewpoint of heat dissipation performance. Furthermore, addition-curing type heat dissipation grease is particularly useful because it is compressed to the desired thickness and then heat cured, which makes it difficult for the heat dissipation grease to flow out (pumping out) due to expansion and contraction caused by the thermal history of repeated heating and cooling of the heat generating part, thereby improving the reliability of electronic component packages and power modules (for example, Patent Document 10).

[0005] In recent years, there has been a demand for even higher thermal conductivity in heat dissipation materials to accommodate new applications such as higher output and performance in electronic component packages and power modules, semiconductors for self-driving vehicles, and IoT. There is a demand for thermally conductive addition-curable silicone compositions that can meet these requirements. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-327116 A [Patent Document 2] JP 2004-130646 A [Patent Document 3] JP 2009-234112 A [Patent Document 4] JP 2009-209230 A [Patent Document 5] JP 2010-095730 A [Patent Document 6] JP 2008-031336 A [Patent Document 7] JP 2007-177001 A [Patent Document 8] JP 2008-260798 A [Patent Document 9] JP 2009-209165 A [Patent Document 10] JP 2016-053140 A Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE PRESENT EMBODIMENTS The present invention has been made in consideration of the above circumstances, and has as its object to provide a thermally conductive addition-curable silicone composition that has excellent heat dissipation properties. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a thermally conductive addition-curable silicone composition, comprising: (A) At least one aliphatic unsaturated hydrocarbon group per molecule, and a kinetic viscosity at 25°C of 60 to 100,000 mm 2 / s, (B) a phenol compound: an amount of 0.01 to 10% by mass based on the total mass of the composition; (C) Silver powder: 10 to 98% by mass of the entire composition; (D) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule: an effective amount sufficient for the composition to form a cured product; (E) a platinum group metal catalyst: an effective amount; The present invention provides a thermally conductive addition-curable silicone composition comprising:

[0009] Such a thermally conductive addition-curable silicone composition has excellent heat dissipation properties.

[0010] In the present invention, the component (B) is preferably a phenol compound represented by the following general formula (1A). [ka] (In the formula, R 1 represents a hydrogen atom, a halogen atom, a cyano group, or a hydroxyl group. Az represents a linear, branched, or cyclic (ka+2)-valent hydrocarbon group having 1 to 20 carbon atoms, or a fluorinated hydrocarbon group, in which -CH2- constituting the hydrocarbon group is -O-, -C(=O)-, or -Si(R 2 R 3 )- may be substituted. 2 , R 3 is a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, or a phenyl group. Each Xf independently represents a hydrogen atom, a halogen atom, a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a fluorine atom, an alkoxy group having 1 to 10 carbon atoms which may be substituted with a fluorine atom, or an electron-withdrawing group. Z represents a single bond or an oxygen atom. Each ring ZZ independently represents an aromatic monocyclic or polycyclic ring having 3 to 20 carbon atoms. The carbon atom of the ring ZZ may be substituted with a nitrogen atom, an oxygen atom, or a sulfur atom. ka represents an integer of 0 to 2. kb and kd represent 1 or 2. kc and ke represent integers of 0 to 2.)

[0011] Such a thermally conductive addition-curable silicone composition has superior heat dissipation properties.

[0012] In the present invention, the component (B) is preferably a phenol compound represented by the following general formula (1B). [ka] (In the formula, Az' represents a linear, branched, or cyclic (ka+2)-valent hydrocarbon group or a fluorinated hydrocarbon group having 1 to 19 carbon atoms, and -CH2- constituting the hydrocarbon group is -O-, -C(=O)-, or -Si(R 2 R 3 ka represents 0 or 1. kb, kc, kd, and ke represent 1 or 2. R 1 , R 2 , R 3 is the same as above.)

[0013] Such a thermally conductive addition-curable silicone composition will more reliably exhibit excellent heat dissipation properties.

[0014] In the present invention, the average particle size of the component (C) is preferably 0.01 to 300 μm.

[0015] Such a thermally conductive addition-curable silicone composition results in a homogeneous composition that is not too viscous and has excellent extensibility.

[0016] In the present invention, it is preferable that the composition further contains an effective amount of (F) one or more addition curing reaction inhibitors selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds.

[0017] Such a thermally conductive addition-curable silicone composition provides the desired sufficient shelf life and pot life, and there is no risk of the curability of the silicone composition decreasing.

[0018] In the present invention, the above-described thermally conductive addition-curable silicone composition is sandwiched between two silicon plates with a diameter of 12.7 mm, and heat-cured at 125°C for 1 hour under a pressure of 0.14 MPa to prepare a test piece for measuring thermal resistance. The thermal resistance value of the thermally conductive addition-curable silicone cured product is measured using a thermal conductivity measuring device. Furthermore, the thickness of the test piece is measured with a microgauge, and the thickness of the thermally conductive addition-curable silicone cured product is calculated from the difference with the thickness of the silicon plates that was measured in advance. Thereafter, the thickness of the thermally conductive addition-curable silicone cured product (μm) ÷ the thermal resistance value of the thermally conductive addition-curable silicone cured product (mm 2 The present invention provides a thermally conductive addition-curable silicone cured product, which has a thermal conductivity of 7.0 W / m K or more when the thermal conductivity of the thermally conductive addition-curable silicone cured product is calculated from the thermal conductivity (T / T) of the cured product.

[0019] Such a thermally conductive addition-curable silicone cured product has excellent heat dissipation properties. Effect of the Invention

[0020] The thermally conductive addition-curable silicone composition of the present invention achieves high thermal conductivity by blending a phenolic compound and silver powder, and as a result, when mounted in an electronic component package or power module, it can exhibit excellent heat dissipation performance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] As described above, there has been a need for the development of a thermally conductive addition-curable silicone composition that has excellent heat dissipation properties.

[0022] As a result of intensive research conducted by the inventors in order to achieve the above-mentioned object, they discovered that a thermally conductive addition-curable silicone composition with excellent heat dissipation properties can be obtained by combining specific amounts of an aliphatic unsaturated hydrocarbon group-containing organopolysiloxane, a phenolic compound, silver powder, an organohydrogenpolysiloxane, and a platinum group metal catalyst, which led to the completion of the present invention.

[0023] That is, the present invention provides a thermally conductive addition-curable silicone composition, comprising: (A) At least one aliphatic unsaturated hydrocarbon group per molecule, and a kinetic viscosity at 25°C of 60 to 100,000 mm 2 / s, (B) a phenol compound: an amount of 0.01 to 10% by mass based on the total mass of the composition; (C) Silver powder: 10 to 98% by mass of the entire composition; (D) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule: an effective amount sufficient for the composition to form a cured product; (E) a platinum group metal catalyst: an effective amount; The thermally conductive addition-curable silicone composition comprises:

[0024] The present invention will be described in detail below, but the present invention is not limited thereto.

[0025] Thermally conductive addition-curable silicone composition The thermally conductive addition-curable silicone composition of the present invention contains the following components (A) to (E), and, if necessary, component (F) and / or other components. Each component is described in detail below.

[0026] Component (A) Component (A) has at least one, preferably 1 to 100, and more preferably 2 to 50 aliphatic unsaturated hydrocarbon groups in one molecule, and has a kinetic viscosity at 25°C of 60 to 100,000 mm 2 / s is an organopolysiloxane.

[0027] The aliphatic unsaturated hydrocarbon group is preferably a monovalent hydrocarbon group having an aliphatic unsaturated bond and having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and more preferably an alkenyl group. Examples of alkenyl groups include vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, and octenyl groups. Vinyl groups are particularly preferred. The aliphatic unsaturated hydrocarbon group may be bonded to either a silicon atom at the molecular chain terminal or a silicon atom in the molecular chain, or may be bonded to both.

[0028] The organic group other than the aliphatic unsaturated hydrocarbon group bonded to the silicon atom of the organopolysiloxane is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl groups, and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, and chlorine, or cyano groups, such as chloromethyl, chloropropyl, bromoethyl, trifluoropropyl, and cyanoethyl groups. In particular, methyl and trifluoropropyl groups are preferred.

[0029] The organopolysiloxane has a kinetic viscosity at 25° C. of 60 to 100,000 mm 2 / s, preferably 100 to 30,000 mm 2 / s. The kinetic viscosity is 60 mm 2 If the viscosity is less than 100,000 mm / s, the physical properties of the thermally conductive addition-curable silicone composition will decrease, and 2 If it exceeds this value, the extensibility of the thermally conductive addition-curable silicone composition will be poor.

[0030] In the present invention, the kinematic viscosity is a value measured at 25° C. using an Ubbelohde-type Ostwald viscometer (the same applies hereinafter).

[0031] The molecular structure of the organopolysiloxane is not particularly limited as long as it has the above properties, and examples thereof include a linear structure, a branched structure, a partially branched structure, and a linear structure having a cyclic structure. In particular, it is preferable that the main chain is composed of a repeating diorganosiloxane unit and has a linear structure in which both ends of the molecular chain are blocked with triorganosiloxy groups. The organopolysiloxane having the linear structure may have a partially branched structure or a cyclic structure.

[0032] The blending amount of component (A) is preferably 1.5 to 89 mass% of the total composition, more preferably 1.7 to 50 mass%, and even more preferably 2 to 20 mass%. If it is 89 mass% or less, the thermal conductivity will not be poor, and if it is 1.5 mass% or more, the viscosity of the composition will not increase more than necessary, and workability will not be reduced.

[0033] The organopolysiloxanes can be used alone or in combination of two or more.

[0034] (B) Component Component (B) is a phenolic compound, which is blended as an additive to the thermally conductive addition curable silicone composition. The phenolic compound is preferably a phenolic compound represented by the following general formula (1A). In the following explanation, some structures represented by chemical formulas may have asymmetric carbons, and may have enantiomers or diastereomers. In such cases, a single formula will be used to represent these isomers. These isomers may be used alone or as a mixture. [ka] (In the formula, R 1represents a hydrogen atom, a halogen atom, a cyano group, or a hydroxyl group. Az represents a linear, branched, or cyclic (ka+2)-valent hydrocarbon group having 1 to 20 carbon atoms, or a fluorinated hydrocarbon group, in which -CH2- constituting the hydrocarbon group is -O-, -C(=O)-, or -Si(R 2 R 3 )- may be substituted. 2 , R 3 is a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, or a phenyl group. Each Xf independently represents a hydrogen atom, a halogen atom, a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a fluorine atom, an alkoxy group having 1 to 10 carbon atoms which may be substituted with a fluorine atom, or an electron-withdrawing group. Z represents a single bond or an oxygen atom. Each ring ZZ independently represents an aromatic monocyclic or polycyclic ring having 3 to 20 carbon atoms. The carbon atom of the ring ZZ may be substituted with a nitrogen atom, an oxygen atom, or a sulfur atom. ka represents an integer of 0 to 2. kb and kd represent 1 or 2. kc and ke represent integers of 0 to 2.)

[0035] Specific examples of Az which is a linear, branched or cyclic (ka+2)-valent hydrocarbon group having 1 to 20 carbon atoms include the following. [ka] (In the formula, the dashed lines represent bonds.)

[0036] [ka] (In the formula, the dashed lines represent bonds.)

[0037] [ka] (In the formula, the dashed lines represent bonds.)

[0038] Specific examples of the linear, branched or cyclic (ka+2)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms for Az include the above-mentioned hydrocarbon groups in which some or all of the hydrogen atoms have been substituted with fluorine atoms. In addition, -CH2- constituting the hydrocarbon group may be -O-, -C(=O)-, or -Si(R 2 R 3 The number of carbon atoms in Az is preferably 2 to 18, more preferably 3 to 16, and further preferably 4 to 14. In addition, a part of -CH2- constituting the hydrocarbon group may be replaced by -Si(R 2 R 3 )- or -Si(R 2 R 3 )-O- is preferably substituted.

[0039] R 2 , R 3 Specific examples of the linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0040] Specific examples of the linear, branched, or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a fluorine atom for Xf include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a cyclopropyl group, and a cyclobutyl group, a trifluoromethyl group, and a 2,2,2-trifluoroethyl group.

[0041] Specific examples of the alkoxy group having 1 to 10 carbon atoms which may be substituted with a fluorine atom for Xf include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, a trifluoromethoxy group, and a 2,2,2-trifluoroethoxy group.

[0042] Specific examples of the electron-withdrawing group of Xf include a carbonyl group, an alkoxycarbonyl group, a cyano group, a nitro group, a sulfo group, a formyl group, a sulfonate ester group, an amide group, -OC(=O)-G- (G is a sulfur atom or NH), and the like.

[0043] Specific examples of the aromatic monocyclic or polycyclic ring having 3 to 20 carbon atoms for the ring ZZ include the following: The ring ZZ may further have a substituent as shown below. [ka]

[0044] The phenol compound represented by the above general formula (1A) is particularly preferably a phenol compound represented by the following general formula (1B). [ka] (In the formula, Az' represents a linear, branched, or cyclic (ka+2)-valent hydrocarbon group or a fluorinated hydrocarbon group having 1 to 19 carbon atoms, and -CH2- constituting the hydrocarbon group is -O-, -C(=O)-, or -Si(R 2 R 3 ka represents 0 or 1. kb, kc, kd, and ke represent 1 or 2. R 1 , R 2 , R 3 is the same as above.)

[0045] Specific examples of the compounds represented by the above general formulas (1A) and (1B) include the following. [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] The blending amount of component (B) is 0.01 to 10% by mass of the entire composition, preferably 0.03 to 5% by mass, and more preferably 0.05 to 1.0% by mass. A blending amount of less than 0.01% by mass is not effective in improving the heat dissipation of the thermally conductive addition cured silicone composition, and even if it exceeds 10% by mass, the effect of improving heat dissipation is not significantly increased, which is uneconomical and therefore not preferred.

[0053] (C) Component The component (C) is silver powder. The method for producing the silver powder is not particularly limited, but examples thereof include electrolysis, pulverization, heat treatment, atomization, reduction, etc. The shape of the silver powder is not particularly limited, and may be flake, spherical, granular, irregular, dendritic, needle-like, etc.

[0054] If the average particle size of component (C) is 0.01 μm or more, the viscosity of the resulting composition will not be too high and the composition will have excellent extensibility, and if it is 300 μm or less, the resulting composition will be uniform, so the range of 0.01 to 300 μm, preferably 0.1 to 100 μm, and more preferably 1 to 50 μm, is preferred. The average particle size can be determined, for example, as the volume-based average value (or median size) in particle size distribution measurement by laser light diffraction method.

[0055] The component (C) can be used either alone or in combination of two or more different types, with no particular limitation to the ratio.

[0056] The blending amount of component (C) is 10 to 98% by mass, preferably 70 to 97% by mass, and more preferably 80 to 95% by mass, of the total composition. If it is more than 98% by mass, the viscosity of the composition may increase significantly, decreasing workability, and if it is less than 10% by mass, the thermal conductivity may be poor.

[0057] (D) Component Component (D) is an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule, i.e., an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms (SiH groups) in one molecule, particularly preferably 2 to 100, and even more preferably 2 to 50. The organohydrogenpolysiloxane may be one in which the SiH groups in the molecule can undergo an addition reaction with the aliphatic unsaturated hydrocarbon groups in component (A) described above in the presence of a platinum group metal catalyst to form a crosslinked structure.

[0058] The molecular structure of the organohydrogenpolysiloxane is not particularly limited as long as it has the above-mentioned properties, and examples thereof include a linear structure, a branched structure, a cyclic structure, a partially branched structure, and a linear structure having a cyclic structure, etc. A linear structure or a cyclic structure is preferred.

[0059] The organohydrogenpolysiloxane preferably has a kinetic viscosity at 25° C. of 1 to 1,000 mm 2 / s, more preferably 10 to 300 mm 2 / s. The kinetic viscosity is 1 mm 2 / s or more, there is no risk of a decrease in the physical properties of the thermally conductive addition-curable silicone composition, and 2 If this is the case, the thermally conductive addition-curable silicone composition will have good extensibility.

[0060] The organic group bonded to the silicon atom of the organohydrogenpolysiloxane may be an unsubstituted or substituted monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon group. In particular, it is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. For example, it may be an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, or a dodecyl group, an aryl group such as a phenyl group, an aralkyl group such as a 2-phenylethyl group or a 2-phenylpropyl group, or a group in which some or all of the hydrogen atoms of these groups are substituted with a halogen atom such as a fluorine, bromine, or chlorine atom, a cyano group, or an epoxy ring-containing organic group (a glycidyl group or a glycidyloxy group-substituted alkyl group), such as a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, a cyanoethyl group, a 2-glycidoxyethyl group, a 3-glycidoxypropyl group, or a 4-glycidoxybutyl group. Among these, a methyl group or a trifluoropropyl group is preferable.

[0061] The organohydrogenpolysiloxanes may be used alone or in combination of two or more.

[0062] The amount of organohydrogenpolysiloxane (D) is an effective amount sufficient for the composition to form a cured product, and is preferably an amount such that the number of SiH groups in (D) relative to the total number of aliphatic unsaturated hydrocarbon groups in (A) is 0.5 to 10, more preferably 0.7 to 7.5, and even more preferably 1.0 to 5.0. If the amount of (D) is equal to or greater than the lower limit, the addition reaction proceeds sufficiently and crosslinking is sufficient. If the amount is equal to or less than the upper limit, the crosslinked structure does not become non-uniform and the shelf life of the composition does not deteriorate.

[0063] (E) Component Component (E) is a platinum group metal catalyst, which functions to promote the addition reaction of the above-mentioned components. The platinum group metal catalyst may be any of those conventionally known for use in addition reactions. Examples include platinum-based, palladium-based, and rhodium-based catalysts, among which platinum or platinum compounds, which are relatively easy to obtain, are preferred. Examples include simple platinum, platinum black, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, and platinum coordination compounds. The platinum group metal catalyst may be used alone or in combination of two or more.

[0064] The amount of the (E) component to be blended should be an effective amount as a catalyst, that is, an effective amount required to promote the addition reaction and cure the thermally conductive addition-curable silicone composition of the present invention. The amount is preferably 0.1 to 500 ppm, more preferably 1 to 200 ppm, and even more preferably 10 to 100 ppm, based on the mass of the platinum group metal atom relative to the entire composition. If the amount of the catalyst is equal to or greater than the lower limit, the catalytic effect is obtained, and if the amount is equal to or less than the upper limit, the catalytic effect is sufficient and economical.

[0065] In addition to the components described above, the following optional components may also be added to the thermally conductive addition-curable silicone composition of the present invention, as necessary.

[0066] Ingredient (F) The component (F) is one or more addition curing reaction inhibitors selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds that suppress the progress of hydrosilylation reactions at room temperature, and can be added to extend shelf life and pot life. The addition curing reaction inhibitor can be a known addition curing reaction inhibitor used in addition curing silicone compositions. Examples of the addition curing reaction inhibitor include acetylene compounds such as acetylene alcohols (e.g., ethynylmethyldecylcarbinol, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol), various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole, organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

[0067] When component (F) is blended, the blending amount may be an effective amount, and is preferably 0.05 to 10 parts by mass, more preferably 0.07 to 5 parts by mass, and even more preferably 0.1 to 2 parts by mass, per 100 parts by mass of component (A). When the amount of the reaction inhibitor is 0.05 parts by mass or more, the desired sufficient shelf life and pot life are obtained, and when it is 10 parts by mass or less, the curability of the silicone composition is not reduced.

[0068] The reaction inhibitor may be diluted with organo(poly)siloxane, toluene, or the like to improve dispersibility in the silicone composition.

[0069] Other Ingredients The thermally conductive addition curable silicone composition of the present invention may contain a non-reactive organo(poly)siloxane such as methylpolysiloxane in order to adjust the strength and viscosity of the composition. Furthermore, one or more conventionally known thermally conductive fillers other than silver may be used in combination. Furthermore, hydrolyzable organopolysiloxanes, various modified silicones, and hydrolyzable organosilanes may be blended for the purpose of improving the filling property of the thermally conductive filler or for the purpose of imparting adhesiveness to the composition. Furthermore, a solvent may be blended to adjust the viscosity of the composition. Furthermore, in order to prevent deterioration of the thermally conductive addition curable silicone composition, a conventionally known antioxidant such as 2,6-di-tert-butyl-4-methylphenol may be included as necessary. Furthermore, dyes, pigments, flame retardants, anti-settling agents, thixotropy improvers, etc. may be blended as necessary.

[0070] Producing a thermally conductive addition-curable silicone composition The method for producing the thermally conductive addition-curable silicone composition of the present invention will now be described. The method for producing the thermally conductive addition-curable silicone composition of the present invention is not particularly limited, but includes the step of producing a thermally conductive addition-curable silicone composition containing the above-mentioned components (A) to (E), and optionally also component (F) and other components.

[0071] The above-mentioned components (A) to (E), and optionally the component (F) and other components, can be mixed in a mixing machine, for example, using a mixer such as Trimix, Twinmix, Planetary Mixer (all of which are registered trademarks of Inoue Seisakusho Co., Ltd.), Ultra Mixer ( Z Examples of such a method include using a mixer such as HIBISMIX (registered trademark of mixer manufactured by Primix Corporation) or a mixer manufactured by Hosoda Kogyo Co., Ltd., and mixing is usually performed for 3 minutes to 24 hours, preferably 5 minutes to 12 hours, and particularly preferably 10 minutes to 6 hours at 25° C. Deaeration may be performed during mixing, or mixing may be performed while heating at a temperature in the range of 40 to 170° C.

[0072] In the present invention, from the viewpoint of enabling the thermally conductive addition-curable silicone composition to exhibit good thermal conductivity, it is preferable to first mix components (A) and (C) at 70° C., and then mix components (B), (D), and (E) at 25° C. When the optional component (F) is added, it is preferable to first mix components (A) and (C), then mix component (F), and then mix components (B), (D), and (E).

[0073] The thermally conductive addition curable silicone composition of the present invention has a viscosity measured at 25°C of preferably 10 to 1,000 Pa·s, more preferably 20 to 700 Pa·s, and even more preferably 40 to 600 Pa·s. If the viscosity is 10 Pa·s or more, the workability is not impaired, such as shape retention being difficult and silver powder not settling. If the viscosity is 1,000 Pa·s or less, the workability is not impaired, such as discharge or application being difficult. The above-mentioned viscosity can be obtained by adjusting the blending amounts of each of the above-mentioned components. The above-mentioned viscosity can be measured at 25°C, for example, using a Malcolm viscometer (type PC-1T).

[0074] Furthermore, the cured product of the thermally conductive addition-curable silicone composition of the present invention typically has a thermal conductivity of 0.5 to 100 W / m K, but in order to exhibit excellent heat dissipation performance when mounted in an electronic component package or power module, it is preferable for the cured product to have a thermal conductivity of 7.0 W / m K or greater.

[0075] The curing conditions when heat curing the thermally conductive addition curable silicone composition of the present invention are not particularly limited, but are typically 80 to 200°C, preferably 100 to 180°C, for 15 minutes to 4 hours, preferably 30 minutes to 2 hours.

[0076] In particular, the thermally conductive addition-curable silicone cured product of the present invention is prepared by sandwiching the above-described thermally conductive addition-curable silicone composition between two silicon plates with a diameter of 12.7 mm, heat-curing the composition at 125°C for one hour under a pressure of 0.14 MPa, preparing a test piece for thermal resistance measurement, measuring the thermal resistance of the thermally conductive addition-curable silicone cured product using a thermal conductivity measuring device, measuring the thickness of the test piece with a microgauge, and calculating the thickness of the thermally conductive addition-curable silicone cured product from the difference with the thickness of the silicon plates that was previously measured, and then calculating the thickness of the thermally conductive addition-curable silicone cured product by dividing the thickness of the thermally conductive addition-curable silicone cured product (μm) by the thermal resistance of the thermally conductive addition-curable silicone cured product (mm 2 When the thermal conductivity of the heat-conductive addition-curable silicone cured product is calculated from the thermal conductivity (K / W), it is preferable that the thermal conductivity be 7.0 W / m·K or greater. EXAMPLES

[0077] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The kinetic viscosity is the value at 25°C measured with an Ubbelohde-type Ostwald viscometer.

[0078] First, the following components for preparing the thermally conductive addition-curable silicone composition of the present invention were prepared.

[0079] Component (A) A-1: Both ends are blocked with dimethylvinylsilyl groups, and the kinetic viscosity at 25°C is 600mm 2 / s Dimethylpolysiloxane A-2: Both ends are blocked with dimethylvinylsilyl groups, and the kinetic viscosity at 25°C is 30,000mm 2 / s Dimethylpolysiloxane A-3: The kinetic viscosity at 25°C represented by the following formula (2) is 800mm 2 / s organopolysiloxane [ka]

[0080] (B) Component B-1: A phenol compound represented by the following formula (3): [ka] B-2: A phenol compound represented by the following formula (4): [ka] B-3: A phenol compound represented by the following formula (5): [ka] B-4: A phenol compound represented by the following formula (6): [ka] B-5: A phenol compound represented by the following formula (7): [ka]

[0081] (C) Component C-1: Average particle size 15 μm, tap density 4.0 g / mL, specific surface area 0.5 m 2 / g flake silver powder C-2: Average particle size 4 μm, tap density 2.2 g / mL, specific surface area 2.0 m 2 / g flake silver powder C-3: Average particle size 4μm, tap density 2.3g / mL, specific surface area 0.9m 2 / g flake silver powder C-4: Average particle size 2μm, tap density 2.4g / mL, specific surface area 0.9m 2 / g flake silver powder C-5: Average particle size 3μm, tap density 6.9g / mL, specific surface area 0.2m 2 / g spherical silver powder

[0082] (D) Component D-1: Methylhydrogendimethylpolysiloxane represented by the following formula (8): (Kinematic viscosity at 25°C = 100mm 2 / s) [ka] D-2: Methyl hydrogen trifluoropropyl methyl polysiloxane represented by the following formula (9): (Kinematic viscosity at 25°C = 60mm 2 / s) [ka]

[0083] (E) Component E-1: A solution of platinum-divinyltetramethyldisiloxane complex dissolved in the same dimethylpolysiloxane as A-1 (platinum atom content: 1% by mass) E-2: A solution of platinum-divinyltetramethyldisiloxane complex dissolved in ethanol (platinum atom content: 3% by mass)

[0084] Ingredient (F) F-1: 1-ethynyl-1-cyclohexanol represented by the following formula (10) [ka]

[0085] [Examples 1 to 17, Comparative Examples 1 to 7] Preparation of Thermally Conductive Addition-Cure Silicone Compositions Thermally conductive addition-curable silicone compositions were prepared by blending the above components (A) to (F) in the amounts and by the methods shown below in Tables 1 to 4. In the tables, SiH / SiVi is the ratio of the total number of SiH groups in component (D) to the total number of alkenyl groups in component (A). Components (A) and (C) were added to 0.3 liters of Hibismix (manufactured by Primix Corporation) and mixed for 1 hour at 70° C. After cooling to 40° C. or less, components (F), (E), (D), and (B) were added and mixed uniformly to prepare a composition. For each of the thermally conductive addition-curable silicone compositions obtained by the above method, the viscosity and thermal conductivity were measured according to the following methods. The results are shown in Tables 1 to 4.

[0086] [viscosity] The absolute viscosity of each thermally conductive addition-curable silicone composition was measured at 25° C. using a Malcolm viscometer (Type PC-1T) (rotor A, 10 rpm, shear rate 6 [1 / s]).

[0087] [Thermal Conductivity] Each heat-conductive addition-curing silicone composition was sandwiched between two silicon plates with a diameter of 12.7 mm, and heat-cured at 125°C for 1 hour under a pressure of 0.14 MPa to prepare a test piece for measuring heat resistance, and measure the heat resistance value of the heat-conductive addition-curing silicone cured product.Furthermore, the thickness of the test piece was measured with a micro gauge, and the thickness of the heat-conductive addition-curing silicone cured product was calculated from the difference with the thickness of the silicon plate that had been measured in advance.Then, the thermal conductivity of the heat-conductive addition-curing silicone cured product was derived from the following formula. (Thickness of the thermally conductive addition-cured silicone, μm) ÷ (Thermal resistance of the thermally conductive addition-cured silicone, mm 2 K / W) For the thermal resistance measurement, Nanoflash (manufactured by Nitsche, LFA447) was used.

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3]

[0091] [Table 4]

[0092] The results in Tables 1 to 4 show that the cured products of the thermally conductive addition-curable silicone compositions of Examples 1 to 17 which satisfy the requirements of the present invention have significantly improved thermal conductivity due to the addition of a phenol compound as component (B), compared to the cured products of the corresponding thermally conductive addition-curable silicone compositions of Comparative Examples 1 to 7 which do not contain a phenol compound as component (B).

[0093] Therefore, the thermally conductive addition-curable silicone composition of the present invention achieves high thermal conductivity by blending a phenolic compound with silver powder, and as a result, when mounted in an electronic component package or power module, it is able to exhibit excellent heat dissipation performance.

[0094] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention.

Claims

1. A thermally conductive addition-curable silicone composition comprising: (A) A copolymer having at least one aliphatic unsaturated hydrocarbon group per molecule and a kinetic viscosity at 25°C of 60 to 100,000 mm ２ / s, (B) a phenol compound represented by the following general formula (1B): an amount of 0.01 to 10% by mass based on the total mass of the composition; (C) Silver powder: 10 to 98% by mass of the entire composition; (D) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms per molecule: an effective amount sufficient for the composition to form a cured product; (E) a platinum group metal catalyst: an effective amount, 1. A thermally conductive addition-curable silicone composition comprising: 【Chemistry 1】 (In the formula, Az' represents a linear, branched or cyclic hydrocarbon group having 1 to 19 carbon atoms and a valence of (ka+2), or a fluorinated hydrocarbon group, and one of --CH 2 -- constituting the hydrocarbon group may be substituted with --O--, --C(═O)--, or --Si(R 2 R 3 )--. ka represents 0 or 1. kb, kc, kd and ke represent 1 or 2. R 1 represents a hydrogen atom, a halogen atom, a cyano group, or a hydroxyl group. R 2 and R 3 represent a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, or a phenyl group.)

2. 2. The thermally conductive addition-curable silicone composition according to claim 1, wherein the average particle size of component (C) is 0.01 to 300 μm.

3. 3. The thermally conductive addition-curable silicone composition according to claim 1 or 2, further comprising (F) an effective amount of one or more addition-curing reaction inhibitors selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds.

4. The thermally conductive addition-curable silicone composition according to any one of claims 1 to 3 is sandwiched between two silicon plates having a diameter of 12.7 mm, and heat-cured at 125°C for 1 hour under a pressure of 0.14 MPa to prepare a test piece for measuring thermal resistance. The thermal resistance value of the thermally conductive addition-curable silicone cured product is measured using a thermal conductivity measuring device. Furthermore, the thickness of the test piece is measured with a microgauge, and the thickness of the thermally conductive addition-curable silicone cured product is calculated from the difference with the thickness of the silicon plates measured in advance. Thereafter, the thickness (μm) of the thermally conductive addition-curable silicone cured product is divided by the thermal resistance value (mm ２ .The thermal conductivity of the thermally conductive addition-cured silicone cured product is 7.0 W / m.K or more when the thermal conductivity of the thermally conductive addition-cured silicone cured product is calculated from the thermal conductivity (W / m.K / W).

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