JPWO2018088416A1 - Thermally conductive silicone composition, cured product thereof, and method of producing the same - Google Patents

Abstract

(A) Organopolysiloxane, (B) spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm 2 or less, and an average particle diameter of 50 to 150 μm, and (C) an average particle diameter of 0.1 Conductive silicone composition containing 5 to 5 μm spherical or unshaped shaped aluminum oxide powder, wherein the blending ratio of the components (B) and (C) is 5: 5 to 9.5: 0.5 Yes, the total amount of the components (B) and (C) is 80 to 90% by volume in the composition, and the thermal conductivity of the composition is 5.5 W / m in the hot disc method according to ISO 22007-2. -A high thermal conductivity silicone composition which is K or more and whose viscosity at 25 ° C is 30 to 800 Pa · s when measured at a rotation speed of 10 rpm by a spiral viscometer.

Description

  The present invention relates to a silicone composition excellent in thermal conductivity, and particularly when used as a heat dissipation member for electronic components, heat generating electronic components such as power devices, transistors, thyristors, CPUs (central processing units), etc. The present invention relates to a highly insulating, high thermal conductivity silicone composition that can be incorporated into electronic devices without being damaged.

  In heat-generating electronic components such as power devices, transistors, thyristors, and CPUs, how to remove heat generated during use is an important issue. Heretofore, as such a heat removal method, it is common practice to attach a heat generating electronic component to a heat radiation fin or a metal plate via an electrically insulating heat radiation sheet, and to release heat, as the heat radiation sheet The thing which made the silicone resin disperse the heat conductive filler is used.

  In recent years, with the high integration of circuits in electronic parts, the calorific value also increases, and the thermal conductivity at high temperatures such as 100 ° C. or more, particularly 150 ° C. environment may be important. From this, materials having higher thermal conductivity than ever before are required. In order to improve the thermal conductivity of the thermally conductive material, a method in which a filler showing high thermal conductivity, such as aluminum oxide powder and aluminum nitride powder, has hitherto been contained in a matrix resin is generally used (Patent Document 1-4 4: JP 2005-162555 A, JP 2003-342021 A, JP 2002-280498 A, JP 2005-209765 A).

  Therefore, in order to improve the thermal conductivity, spherical aluminum oxide powder having an average sphericity, an amount of hydroxyl groups, and an average particle diameter of 10 to 50 μm and an average particle diameter of 0.3 to 1 μm are defined. Although the method of the high thermal conductivity resin composition in which the blending ratio and volume ratio of aluminum are specified is disclosed, when the average particle diameter of the spherical aluminum oxide powder is 50 μm at maximum, the problem of insufficient thermal conductivity (Patent Document 5: Patent No. 5755977).

  Although a thermally conductive silicone composition using an alumina powder having an average particle diameter of 0.1 to 100 μm has been proposed, no specific thermal conductivity or viscosity is specified. Further, it is defined by spherical alumina powder having an average particle diameter of 5 to 50 μm (but not including 5 μm) and spherical or irregular shaped alumina powder having an average particle diameter of 0.1 to 5 μm, Although a thermally conductive silicone composition having a defined weight ratio is disclosed, as in Patent Document 5, there is no definition of the average sphericity or the amount of hydroxyl groups of spherical alumina having a large average particle diameter, and the thermal conductivity is improved. There is a problem that it is insufficient for causing the problem (Patent Document 6: Re-issued Patent No. 2002-092693).

JP, 2005-162555, A JP 2003-342021 A Unexamined-Japanese-Patent No. 2002-280498 JP, 2005-209765, A Patent No. 5755977 Patent Reissued Patent 2002-092693

  The present invention has been made in view of the above circumstances, and is to provide a thermally conductive silicone composition excellent in insulation and thermal conductivity, and in particular, a thermally conductive silicone composition suitable as a heat dissipation member for electronic parts. It is to provide.

As a result of intensive investigations to achieve the above object, the present inventors have found that (B) an average sphericity of 0.8 or more and a hydroxyl group of 30 pieces / nm ² or less in the silicone composition containing (A) organopolysiloxane. The above-mentioned spherical aluminum oxide powder having an average particle diameter of 50 to 150 μm and (C) spherical or irregular shaped aluminum oxide powder having an average particle diameter of 0.1 to 5 μm are compounded at a specific ratio by a specific amount. The thermally conductive silicone composition which can solve a subject and whose handleability and workability become favorable can be obtained. In addition, the thermal conductivity of the cured product of the thermally conductive silicone composition at 150 ° C. is 4.0 W / m · K or more in the hot disc method in accordance with ISO 22007-2 so that the thermal conductivity at high temperature is obtained. It is possible to obtain an excellent heat conductive silicone composition. Furthermore, a curing agent can be blended with the present composition to form a curable composition.

Accordingly, the present invention provides the following invention.
1. (A) organopolysiloxane,
(B) Spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm ² or less, and an average particle diameter of 50 to 150 μm, and (C) a spherical or irregular particle having an average particle diameter of 0.1 to 5 μm A high thermal conductivity silicone composition comprising shaped aluminum oxide powder,
Blending ratio volume ratio ((B) :( C)) of the above (B) component and (C) component is 5: 5 to 9.5: 0.5, and the total amount of (B) component and (C) component Is 80 to 90% by volume in the composition,
When the thermal conductivity of the composition is 5.5 W / m · K or more and the viscosity of the composition at 25 ° C. is 10 to 30 rpm when measured at a rotational speed of 10 rpm by a spiral viscometer in the hot disk method according to ISO 22007-2. high thermal conductivity silicone composition which is s.
2. The high thermal conductivity silicone composition according to 1, further comprising (D) a silane coupling agent.
3. The component (D) is represented by the following general formula (1)
-SiR ¹ _a (OR ² ) _3-a (1)
(Wherein, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, and a is 0, 1 or 2) is there.)
The high thermal conductivity silicone composition according to 2, which is an organopolysiloxane containing at least one silyl group represented by 1 in one molecule and having a viscosity of 0.01 to 30 Pa · s at 25 ° C.
4. Furthermore, the maximum value of the (E) central particle diameter is 150 μm or more, and the spherical glass beads or amorphous glass having an SiO ₂ content of 50% by mass or more are contained in an amount of 10% by mass or less The high thermal conductivity silicone composition as described in any of the above.
5. Furthermore, the high thermal conductivity silicone composition according to any one of 1 to 4 comprising a curing agent.
6. 5. Thermally conductive silicone composition of 5 whose thermal conductivity at 150 degrees C of hardened | cured material of high thermal conductivity silicone composition is 4.0 W / m * K or more in the hot disk method based on ISO22007-2.
7. 6. The high thermal conductivity silicone composition according to 6, which is an addition reaction curing type, a condensation reaction curing type or an organic peroxide curing type.
8. 7. The high thermal conductivity silicone composition according to 7 which is addition reaction curable.
Cured | cured material of the high thermal conductivity silicone composition in any one of 9.5-8.
10. The cured product according to 9, wherein the thermal conductivity at 150 ° C is 4.0 W / m · K or more in a hot disk method in accordance with ISO 22007-2.
11. (A) organopolysiloxane,
(B) Spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm ² or less, and an average particle diameter of 50 to 150 μm, and (C) a spherical or irregular particle having an average particle diameter of 0.1 to 5 μm The mixing ratio volume ratio ((B) :( C)) of the component (B) to the component (C) including the step of mixing the shape aluminum oxide powder is 5: 5 to 9.5: 0.5, (B The total amount of the component (C) and the component (C) is 80 to 90% by volume in the composition, and the thermal conductivity of the composition is 5.5 W / m · K or more in the hot disc method according to ISO 22007-2. A method for producing a high thermal conductivity silicone composition, wherein the viscosity of the composition at 25 ° C. is 30 to 800 Pa · s when measured at a rotation speed of 10 rpm by a spiral viscometer.

  According to the present invention, it is possible to provide a high thermal conductivity silicone composition which is excellent in insulation and thermal conductivity.

Hereinafter, the present invention will be described in detail. The "thermally conductive silicone composition" may be abbreviated as "silicone composition".
[(A) component]
The organopolysiloxane (A) is the main component of the silicone composition of the present invention. Examples of the group bonded to the silicon atom in this organopolysiloxane include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and undecyl group. Linear alkyl groups such as dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc .; isopropyl group, tertiary butyl group, isobutyl group, 2-methyl group Branched alkyl groups such as undecyl group and 1-hexylheptyl group; cyclic alkyl groups such as cyclopentyl group, cyclohexyl group and cyclododecyl group; alkenyl groups such as vinyl group, allyl group, butenyl group, pentenyl group and hexenyl group Aryl such as phenyl, tolyl or xylyl Aralkyl groups such as benzyl group, phenethyl group and 2- (2,4,6-trimethylphenyl) propyl group; and halogenated alkyl groups such as 3,3,3-trifluoropropyl group and 3-chloropropyl group It is preferably an alkyl group, an alkenyl group or an aryl group, particularly preferably a methyl group, a vinyl group or a phenyl group.

  The viscosity at 25 ° C. of the organopolysiloxane is not limited, but is preferably in the range of 20 to 100,000 mPa · s, more preferably 50 to 100,000 mPa · s, and still more preferably 50 to 50,000 mPa · s. And 100 to 50,000 mPa · s are particularly preferred. If the viscosity is too low, the physical properties of the silicone composition may be significantly reduced, and if the viscosity is too high, the handling workability of the silicone composition may be significantly reduced.

  The molecular structure of the organopolysiloxane is not limited and includes, for example, linear, branched, partially branched linear, and dendritic (dendrimer-like), preferably linear and partially branched. It is linear. Such organopolysiloxanes include, for example, single polymers having these molecular structures, copolymers composed of these molecular structures, or mixtures of these polymers.

Such organopolysiloxanes include, for example, dimethylpolysiloxanes blocked with dimethylvinylsiloxy groups at both ends of molecular chains, dimethylpolysiloxanes blocked with methylphenylvinylsiloxy groups at both ends of molecular chains, dimethylpolysiloxanes blocked with dimethylvinylsiloxy groups at molecular ends. Methyl phenyl siloxane copolymer, Molecular chain both ends dimethyl vinylsiloxy group blocked dimethyl siloxane · methyl vinyl siloxane copolymer, Molecular chain both ends trimethylsiloxy group blocked dimethyl siloxane · methyl vinyl siloxane copolymer, Molecular chain both ends dimethyl vinyl siloxy group methyl (3 , 3,3-Trifluoropropyl) polysiloxane, Both chain terminal silanol group blocked dimethyl siloxane / methyl vinyl siloxane copolymer, Molecular chain both terminal silanol Dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer, the formula: (CH _{3) 3} siloxane units of the formula represented by SiO _1/2: Table with _{(CH 3) 2 (CH 2} = CH) SiO 1/2 An organosiloxane copolymer comprising a siloxane unit represented by the formula: a siloxane unit represented by the formula CH ₃ SiO _3/2 and a siloxane unit represented by the formula (CH ₃ ) ₂ SiO _2/2; Dimethylpolysiloxane, Molecular chain both terminal silanol group blocked dimethyl siloxane / methylphenyl siloxane copolymer, Molecular chain both terminal trimethoxysiloxy group blocked dimethylpolysiloxane, Molecular chain both terminal trimethoxysilyl group blocked dimethyl siloxane / methylphenyl siloxane copolymer, Molecular Blocking of both terminal methyldimethoxysiloxy groups Methylpolysiloxane, molecular chain both terminal triethoxysiloxy group blocked dimethylpolysiloxane, molecular chain both terminal trimethoxysilylethyl group blocked dimethylpolysiloxane may be mentioned, and one type can be used alone or two or more types can be used in combination as appropriate. .

  When the silicone composition cures by a hydrosilylation reaction, component (A) should be an organopolysiloxane having an average of 0.1 or more silicon-bonded alkenyl groups per molecule (A-I). More preferably, it is an organopolysiloxane having an average of 0.5 or more silicon-bonded alkenyl groups in one molecule, and an organic poly having an average of 0.8 or more silicon-bonded alkenyl groups or more in one molecule. More preferably, it is a siloxane. This is because when the average value of silicon-bonded alkenyl groups in one molecule is less than the lower limit of the above range, the resulting silicone composition tends not to be sufficiently cured. As the silicon-bonded alkenyl group in this organopolysiloxane, the same alkenyl group as described above is exemplified, and a vinyl group is preferable. Further, as the group bonded to a silicon atom other than the alkenyl group in this organopolysiloxane, the same linear alkyl group, branched alkyl group, cyclic alkyl group, aryl group, aralkyl group, halogen as described above are mentioned. Fluorinated alkyl groups are exemplified, preferably alkyl groups and aryl groups, and particularly preferably methyl groups and phenyl groups.

  When the silicone composition cures by a condensation reaction, component (A) is an organopolysiloxane having at least two silanol groups or silicon-bonded hydrolyzable groups in one molecule of (A-II). The silicon-bonded hydrolyzable group in this organopolysiloxane is, for example, an alkoxy group such as methoxy, ethoxy or propoxy; vinyloxy, propenoxy, isopropenoxy, 1-ethyl-2-methylvinyloxy Alkenoxy groups such as: alkoxyalkoxy groups such as methoxyethoxy, ethoxyethoxy and methoxypropoxy groups; Acyloxy groups such as acetoxy groups and octanoyloxy groups; Ketooxime groups such as dimethylketoxime groups and methylethyl ketoxime groups; Dimethylamino groups Amino groups such as diethylamino group and butylamino group; aminoxy groups such as dimethylaminoxoxy group and diethylaminoxy group; and amide groups such as N-methylacetamide group and N-ethylacetamide group. Moreover, as the silanol group in this organopolysiloxane and the group bonded to a silicon atom other than the silicon-bonded hydrolysable group, the same linear alkyl group, branched alkyl group, cyclic alkyl group as described above can be used. And alkenyl groups, aryl groups, aralkyl groups and halogenated alkyl groups.

  When the silicone composition cures by free radical reaction with an organic peroxide, the organopolysiloxane of the component (A) is not limited, but preferably at least one silicon atom in one molecule of (A-III). It is an organopolysiloxane having a bonded alkenyl group. As the group bonded to the silicon atom in this organopolysiloxane, the same linear alkyl group, branched alkyl group, cyclic alkyl group, alkenyl group, aryl group, aralkyl group, halogenated alkyl group as described above Is exemplified, and an alkyl group, an alkenyl group and an aryl group are preferable, and a methyl group, a vinyl group and a phenyl group are more preferable.

  1.0-6.0 mass% in a silicone composition is preferable, and, as for the compounding quantity of (A) component, 1.0-5.8 mass% is more preferable.

[(B) component]
The component (B) is a spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm ² or less, and an average particle diameter of 50 to 150 μm. As long as the above range is satisfied, two or more kinds of two or more kinds having different average particle diameters may be used in combination.

  The crystal structure of the aluminum oxide powder may be either single crystal or polycrystal, but the crystal phase is preferably an α phase from the viewpoint of high thermal conductivity, and the specific gravity is preferably 3.7 or more. If the specific gravity is less than 3.7, the ratio of the pores present in the interior of the particles to the low crystal phase increases, which may make it difficult to increase the thermal conductivity. The particle size adjustment of the aluminum oxide powder can be performed by classification and mixing operations.

  The average sphericity is 0.8 or more, more preferably 0.9 or more. Fluidity may fall that average sphericity is less than 0.8. When the average sphericity is less than 0.8, the contact between the particles becomes remarkable, the unevenness of the sheet surface becomes large, the interface thermal resistance tends to increase, and the thermal conductivity tends to deteriorate. The upper limit is not particularly limited, but the closer to the sphere (average sphericity 1), the better.

The average sphericity in the present invention can be measured as follows by taking a particle image taken with a scanning electron microscope into an image analysis apparatus such as "JSM-7500F" manufactured by JEOL. That is, the projected area (X) and the perimeter (Z) of the particle are measured from the photograph. Assuming that the area of a true circle corresponding to the perimeter (Z) is (Y), the sphericity of the particle can be displayed as X / Y. Therefore, assuming a perfect circle having the same perimeter as the perimeter (Z) of the sample particle, since Z = 2πr and Y = πr ² , Y = π × (Z / 2π) ² , and individual particles The sphericity of can be calculated as sphericity = X / Y = X × 4π / Z ² . The sphericity of 100 particles thus obtained is determined, and the average value thereof is taken as the average sphericity.

The number of hydroxyl groups is 30 / nm ² or less, preferably 25 / nm ² or less. The lower limit is not particularly limited, but may be 5 / nm ² . When the number of surface hydroxyl groups is more than 30 / nm ² , the filling property to the silicone composition is deteriorated, and the thermal conductivity tends to be deteriorated.

  The number of hydroxyl groups in the present invention, that is, the surface hydroxyl group concentration, can be measured by Karl Fischer coulometric titration method, for example, by Mitsubishi Chemical Co., Ltd. under the trade name "minor water content measuring device CA-100". Specifically, 0.3 to 1.0 g of a sample is placed in a water vaporizer, and heated and heated by an electric heater while supplying dehydrated argon gas as a carrier gas. In the Karl-Fisher coulometric measurement method, water generated at temperatures exceeding 200 ° C. and up to 900 ° C. is defined as the amount of surface hydroxyl groups. The concentration of surface hydroxyl groups is calculated from the measured amount of water and the specific surface area.

  The average particle size is 50 to 150 μm, preferably 60 to 140 μm. When the average particle size is less than 50 μm, the contact between particles is reduced, and the thermal conductivity tends to be deteriorated due to the increase in the thermal contact resistance between particles. Moreover, when it exceeds 150 micrometers, the unevenness | corrugation of a sheet | seat surface may become large and interface thermal resistance may increase.

  The average particle diameter in the present invention can be measured using a laser diffraction type particle size distribution measuring apparatus, for example, “Laser diffraction type particle size distribution measuring apparatus SALD-2300” manufactured by Shimadzu Corporation. The evaluation sample is prepared by adding 5 g of 50 cc of pure water and 5 g of a heat conductive powder to be measured to a glass beaker, stirring using a spatula, and then dispersing for 10 minutes with an ultrasonic cleaner. Add the dispersed solution of the thermally conductive material powder drop by drop to the sampler part of the apparatus with a dropper, and wait for the absorbance to stabilize until it becomes measurable. When the absorbance becomes stable in this way, measurement is performed. In a laser diffraction type particle size distribution measuring apparatus, a particle size distribution is calculated from data of light intensity distribution of diffracted / scattered light by particles detected by a sensor. The average particle size is determined by multiplying the value of the particle size to be measured by the relative particle amount (difference%) and dividing by the total relative particle amount (100%). The average particle size is the average diameter of the particles.

[(C) ingredient]
The component (C) is an aluminum oxide powder having an average particle diameter of 0.1 to 5 μm, preferably 0.5 to 2 μm, and may be spherical or amorphous. In addition, things other than a spherical thing are indeterminate shape. As long as the present invention is not impaired, it may be used alone or in combination of two or more kinds having different average particle sizes. When the average particle size is less than 0.1 μm, the contact between particles is reduced, and the thermal conductivity tends to be deteriorated due to the increase in the thermal contact resistance between particles. If the thickness is more than 5 μm, the surface roughness of the sheet becomes large, the interface thermal resistance increases, and the thermal conductivity tends to deteriorate. When the component (C) is spherical, as in the component (B), it is preferable that the average sphericity is 0.8 or more and the number of hydroxyl groups is 30 / nm ² or less. In addition, the measuring method of an average particle diameter, average sphericity, and a hydroxyl group is the same as (B) component.

  The compounding ratio volume ratio ((B) :( C)) of the said (B) component and (C) component is 5: 5-9.5: 0.5, and 6: 4-9: 1 is more preferable. . When the ratio of component (B) is smaller than 5 (volume of component (B) and component (C) total 10, the same applies hereinafter), the packing properties of component (B) and component (C) tend to deteriorate. . On the other hand, when the ratio of the component (C) becomes larger than 9.5, the components (B) and (C) become difficult to be densely packed, and the thermal conductivity tends to decrease.

  The total blending amount of the component (B) and the component (C) is 80 to 90% by volume in the silicone composition, preferably 80 to 85% by volume. If the amount is less than 80% by volume, the thermal conductivity of the silicone composition may be insufficient. If it exceeds 90% by volume, the filling of the thermally conductive filler becomes difficult.

[(D) component]
In the present invention, it is preferable to further include (D) a silane coupling agent, and the (B) component and the (C) component are surface-treated with the (D) silane coupling agent.

(D-I)
(D) As a silane coupling agent, a vinyl type silane coupling agent, an epoxy type silane coupling agent, an acrylic type silane coupling agent, and a long chain alkyl type silane coupling agent etc. are mentioned, and 1 type is individual or Two or more species can be used in combination as appropriate. Among them, long chain alkyl type silane coupling agents are preferable, and decyltrimethoxysilane is preferable.

  As a surface treatment method of the (B) component and the (C) component by the (D-I) component, a spraying method using a fluid nozzle, a stirring method with shear force, a dry method such as a ball mill or a mixer, a water system or an organic solvent A wet method such as a system can be adopted. The stirring method is performed to such an extent that destruction of the spherical aluminum oxide powder does not occur. The in-system temperature in the dry method or the drying temperature after the treatment is appropriately determined in a region where the surface treatment agent does not volatilize or decompose depending on the type of the surface treatment agent, but is 80 to 180 ° C.

  The treatment amount of the component (D-I) is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass in total of the components (B) and (C). If the amount is less than 0.1 parts by mass, the effect is small, and if the amount is more than 5 parts by mass, the effect corresponding to the amount used does not appear.

Organo (D-II) containing at least one silyl group represented by the following general formula (1) in one molecule as component (D) and having a viscosity of 0.01 to 30 Pa · s at 25 ° C. Polysiloxane is mentioned.
-SiR ¹ _a (OR ² ) _3-a (1)
(Wherein, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, and a is 0, 1 or 2) is there.)

（式中、Ｒ¹は独立に非置換又は置換の１価炭化水素基であり、Ｒ²は独立にアルキル基、アルコキシアルキル基、アルケニル基又はアシル基であり、ｂは２〜１００の整数であり、ａは０、１又は２である。）As (D-II) component, the organopolysiloxane represented by following General formula (2) is mentioned.

(Wherein, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, and b is an integer of 2 to 100) And a is 0, 1 or 2.)

In formulas (1) and (2), R ¹ is independently a substituted or unsubstituted monovalent hydrocarbon group having preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms Examples thereof include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups and halogenated alkyl groups. As a linear alkyl group, a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, a decyl group etc. are mentioned, for example. As a branched alkyl group, an isopropyl group, an isobutyl group, a tert- butyl group, 2-ethylhexyl group etc. are mentioned, for example. As a cyclic alkyl group, a cyclopentyl group, a cyclohexyl group, etc. are mentioned, for example. As an alkenyl group, a vinyl group, an allyl group, etc. are mentioned, for example. As an aryl group, a phenyl group, a tolyl group, etc. are mentioned, for example. As an aralkyl group, 2-phenylethyl group, 2-methyl- 2-phenylethyl group etc. are mentioned, for example. Examples of the halogenated alkyl group include 3,3,3-trifluoropropyl group, 2- (nonafluorobutyl) ethyl group, 2- (heptadecafluorooctyl) ethyl group and the like. As R ¹ , a methyl group and a phenyl group are preferable.

In formulas (1) and (2), R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group. Examples of the alkyl group include linear alkyl groups, branched alkyl groups and cyclic alkyl groups similar to those exemplified for R ¹ . As an alkoxy alkyl group, a methoxyethyl group, a methoxypropyl group etc. are mentioned, for example. As an alkenyl group, the same thing as having illustrated in R ¹ is mentioned, for example. The carbon number is preferably 1 to 8. As an acyl group, an acetyl group, an octanoyl group, etc. are mentioned, for example. R ² is preferably an alkyl group, particularly preferably a methyl group or an ethyl group. b is an integer of 2 to 100, preferably 5 to 50; a is 0, 1 or 2, preferably 0.

（式中、Ｍｅはメチル基である。）The following can be mentioned as a preferable specific example of the organopolysiloxane of (D-II) component.

(Wherein, Me is a methyl group)

  The viscosity at 25 ° C. of the organopolysiloxane of the component (D-II) is usually 0.01 to 30 Pa · s, preferably 0.01 to 10 Pa · s. If the viscosity is lower than 0.01 Pa · s, oil bleeding is likely to be generated from the silicone composition, and there is also a possibility that the silicone composition may easily sag. If the viscosity is more than 30 mPa · s, the flowability of the resulting silicone composition may be extremely poor, and the coating workability may be deteriorated. In addition, this viscosity is a measured value by a rotational viscometer (same below).

  5-900 mass parts is preferable with respect to 100 mass parts of (A) component, as for the compounding quantity of (D-II) component, 10-900 mass parts is more preferable, and 20-700 mass parts is more preferable.

[(E) ingredient]
In the silicone composition of the present invention, spherical glass beads or amorphous glass having a maximum value of (E) central particle diameter of 150 μm or more and a SiO ₂ content of 50% by mass or more relative to the total amount of silicone composition It is preferable to mix | blend 10 mass% or less. The component (E) is characterized in that the maximum value of the central particle diameter is larger than the average particle diameter of the component (B), and the upper limit of the maximum value is not particularly limited, but may be 300 μm or less. When the component (E) is blended, the thermally conductive silicone composition can be made to have a desired cured thickness of 150 μm or more, even in a very small amount. Materials include soda lime glass, soda lime silica glass, or borosilicate glass. From the viewpoint of uniformity of the cured thickness, it is preferable that the component (E) is spherical rather than amorphous, and when the component (E) is spherical glass beads, the average sphericity is 0.8 or more, as with the component (B). Is preferred.

  It is preferable to add a small amount of the component (E) within the range that does not impair the present invention. Specifically, in order not to significantly reduce the thermal conductivity of the thermally conductive silicone composition, The amount of component F) is preferably 10% by mass or less (0 to 10% by mass). In addition, the measurement of a center particle diameter can be measured by a laser diffraction method, for example, using Shimadzu Corp. make "laser diffraction type | formula particle size distribution measuring apparatus SALD-2300."

  The high thermal conductivity silicone composition of the present invention may be used as it is, or a curing agent may be further blended to form a curable composition.

The curable thermal conductive silicone composition includes the following three forms, and as the organopolysiloxane (A) as the base polymer, the organopoly of the above (A-I) to (A-III) components It is possible to use siloxane and blend the above-mentioned thermally conductive fillers (B) and (C).
[I] Addition reaction curing type thermally conductive silicone composition [II] Condensation reaction curing type thermally conductive silicone composition [III] Organic peroxide curing type thermally conductive silicone composition [I] An addition reaction-curable heat conductive silicone composition is preferred because it does not occur. Below, it shows concretely about each composition.

[I] Addition reaction curing type heat conductive silicone composition When the silicone composition is an addition reaction curing type heat conductive silicone composition which cures by a hydrosilylation reaction, the above-mentioned (A) is shown as the above (A- The component (I) is used and the following components are further contained, and the curing agent is the following components (F) and (G).
(F) organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms,
(G) platinum group metal based curing catalyst,
(H) Addition reaction control agent, if necessary

[(F) component]
An organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms is a component acting as a crosslinking agent. Examples of the group bonded to the silicon atom bond of the organohydrogenpolysiloxane include the same linear alkyl group, branched alkyl group, cyclic alkyl group, aryl group, aralkyl group and halogenated alkyl group as described above. And preferably an alkyl group or an aryl group, particularly preferably a methyl group or a phenyl group. Although the viscosity at 25 degrees C of (F) component is not limited, The range of 1-100,000 mPa * s is preferable, and the range of 1-5,000 mPa * s is more preferable. The molecular structure of the component (F) is not limited, and examples thereof include linear, branched, partially branched linear, cyclic, and dendritic (dendrimer-like). Such organopolysiloxanes include, for example, homopolymers having these molecular structures, copolymers composed of these molecular structures, or mixtures thereof.

As the component (F), for example, dimethylhydrogensiloxy group-capped dimethylpolysiloxane with molecular chain both end trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both terminal dimethylhydrogensiloxy group-capped Dimethyl siloxane / methyl hydrogen siloxane copolymer, siloxane unit represented by the formula: (CH ₃ ) ₃ SiO _1/2 and siloxane unit represented by the formula: (CH ₃ ) ₂ HSiO _1/2 and formula: SiO _{4 / The} organosiloxane copolymer which consists of a siloxane unit represented by ₂ is mentioned, It can be used individually by 1 type or in combination of 2 or more types suitably.

  The compounding amount of the component (F) is an amount necessary for curing of the silicone composition, and specifically, in the component (F) relative to 1 mole of silicon-bonded alkenyl group in the component (A-I) Is preferably in an amount of 0.1 to 10 moles, and more preferably in an amount of 0.1 to 5 moles, particularly 0.1 The amount is preferably in the range of -3.0 mol. This is because when the content of the component is less than the lower limit of the above range, the resulting silicone composition tends to be not sufficiently cured, while when it exceeds the upper limit of the above range, it is obtained The cured silicone becomes very hard and may cause many cracks on the surface.

  (G) A platinum group metal-based curing catalyst is a catalyst for promoting the curing of the silicone composition, for example, chloroplatinic acid, alcohol solution of chloroplatinic acid, olefin complex of platinum, alkenyl siloxane complex of platinum, platinum And a carbonyl complex of

  The compounding amount of the (G) component is an amount necessary for curing of the silicone composition, and specifically, the platinum metal in the (G) component is 0.01 parts by mass unit to the (A-I) component. The amount is preferably in the range of ̃1,000 ppm, and particularly preferably in the range of 0.1 to 500 ppm. This is because when the compounding amount of the component (G) is less than the lower limit of the above range, the resulting silicone composition tends not to be sufficiently cured. The cure rate of the resulting silicone composition is not significantly improved.

(H) Curing Reaction Inhibitor In order to adjust the curing speed of the silicone composition and improve the handling workability, a curing reaction inhibitor can be blended. Curing reaction inhibitors include acetylene compounds such as 2-methyl-3-butyn-2-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol and the like; 3-methyl-3 -En-yne compounds such as pentene-1-yne and 3,5-dimethyl-3-hexene-1-yne; and others, including hydrazine compounds, phosphine compounds, mercaptan compounds and the like, which may be used alone or in combination Two or more species can be used in combination as appropriate.

  Although the compounding quantity of (H) component is not specifically limited, 0.0001-1.0 mass% is preferable with respect to a silicone composition. By setting it as the said range, the workability of a silicone composition and hardening speed become more suitable.

[II] Condensation reaction curing type thermally conductive silicone composition When the silicone composition is a condensation reaction curing type thermally conductive silicone composition, the component (A-II) shown above as the above (A) is used, Furthermore, it contains the following components, and the curing agent is the following (I) component.
(I) a silane having at least three silicon-bonded hydrolyzable groups in one molecule or a partial hydrolyzate thereof
(J) If necessary, a catalyst for condensation reaction

  Examples of the silicon-bonded hydrolyzable group in the component (I) include the same alkoxy group, alkoxyalkoxy group, acyloxy group, ketoxime group, alkenoxy group, amino group, aminoxy group and amido group as described above. In addition to the above hydrolyzable groups, silicon atoms of this silane may be, for example, the same linear alkyl group, branched alkyl group, cyclic alkyl group, alkenyl group, aryl group, aralkyl group, halogen as described above. It is also possible to bind a fluorinated alkyl group. Examples of such silanes or partial hydrolysates thereof include methyltriethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and ethyl orthosilicate.

  The compounding amount of the component (I) is an amount necessary for curing the silicone composition, and specifically, it is in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the component (A-II). It is preferable that it is in the range of 0.1-10 mass parts especially. If the content of this silane or its partial hydrolyzate is less than the lower limit of the above range, the storage stability of the resulting silicone composition may be reduced, while the upper limit of the above range is exceeded. If it is an amount, the curing of the resulting silicone composition may be significantly delayed.

  The component (J) is an optional component, and is not essential when, for example, a silane having a hydrolyzable group such as an aminoxy group, an amino group or a ketoxime group is used as a curing agent. As such a condensation reaction catalyst, for example, organic titanates such as tetrabutyl titanate and tetraisopropyl titanate; organic titanium such as diisopropoxy bis (acetyl acetate) titanium and diisopropoxy bis (ethyl aceto acetate) titanium Chelate compounds; organoaluminum compounds such as aluminum tris (acetylacetonate) and aluminum tris (ethylacetoacetate); organoaluminum compounds such as zirconium tetra (acetylacetonate) and zirconium tetrabutyrate; dibutyltin dioctoate, dibutyltin dilaurate, Organotin compounds such as butyl tin 2-ethyl hexoate; Organics such as tin naphthenate, tin oleate, tin butylate, cobalt naphthenate, zinc stearate Metal salts of rubonic acid; amine compounds such as hexylamine and dodecylamine phosphate, and salts thereof; quaternary ammonium salts such as benzyltriethylammonium acetate; lower fatty acid salts of alkali metals such as potassium acetate and lithium nitrate; dimethylhydroxylamine, And dialkylhydroxylamines such as diethylhydroxylamine; and guanidyl group-containing organosilicon compounds.

  When compounding component (J), the compounding amount may be an amount necessary for curing of the silicone composition, and specifically, 0.01 to 20 parts by mass of 100 parts by mass of component (A) It is preferably in the range, and particularly preferably in the range of 0.1 to 10 parts by mass. This is because when the catalyst is essential, if the content of the catalyst is less than the lower limit of the above range, the resulting silicone composition tends not to be sufficiently cured, while the above range If the upper limit of the above is exceeded, the storage stability of the resulting silicone composition tends to decrease.

[III] Organic peroxide curable thermally conductive silicone composition When the silicone composition is an organic peroxide curable thermally conductive silicone composition, it is shown above as (A) above (A-III) The component is used and the following component is further contained, and the curing agent is the following (K) component.
(K) Organic peroxide

  (K) Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, 2,5-dimethylbis (2,5-t-butylperoxy) hexane, di-t-butyl peroxide, and t- And butyl perbenzoate.

  The compounding amount of the (K) component is an amount necessary for curing of the silicone composition, and specifically, 0.1 to 5 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the (A-III) component. Is preferred. When the compounding amount of the component (K) is less than the lower limit of the above range, the resulting silicone composition tends not to be sufficiently cured, and on the other hand, the silicone composition obtained even if the amount exceeds the upper limit of the above range The curing speed of the material is not significantly improved and may cause a void.

  Furthermore, in the silicone composition of the present invention, as the other optional components, for example, fillers such as zinc oxide, fumed silica, precipitated silica, fumed titanium oxide, etc. as long as the object of the present invention is not impaired Fillers obtained by hydrophobizing the surface of organic silicon compounds with organosilicon compounds; adhesion promoters such as 3-glycidoxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane; other pigments, dyes, fluorescent dyes, heat-resistant additives And a flame retardant such as a triazole compound, and a plasticizer. In addition, in the range which does not impair the effect of this invention, you may mix | blend heat conductive fillers other than (B) component, for example, aluminum powder, copper powder, silver powder, nickel powder, gold powder, zinc oxide powder. And magnesium oxide powder, boron nitride powder, aluminum nitride powder, diamond powder, carbon powder and the like.

[Production method]
The silicone composition of the present invention can be prepared by uniformly mixing predetermined amounts of the above-mentioned components. For example, (A) organopolysiloxane,
(B) Spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm ² or less, and an average particle diameter of 50 to 150 μm, and (C) a spherical or irregular particle having an average particle diameter of 0.1 to 5 μm The mixing ratio volume ratio ((B) :( C)) of the component (B) to the component (C) including the step of mixing the shape aluminum oxide powder is 5: 5 to 9.5: 0.5, (B The total amount of the component (C) and the component (C) is 80 to 90% by volume in the composition, and the thermal conductivity of the composition is 5.5 W / m · K or more in the hot disc method according to ISO 22007-2. The method of manufacturing the highly thermally conductive silicone composition whose viscosity in 25 degreeC of a composition is 30-800 Pa.s is measured at the time of rotation speed 10 rpm measurement by a spiral viscometer. Furthermore, the step of mixing optional components may be included.

[High thermal conductivity silicone composition]
The thermal conductivity of the thermally conductive silicone composition is a high thermal conductivity silicone composition of 5.5 W / m · K or more in the hot disc method according to ISO 22007-2, and 6.0 W / m · K or more More preferable. The upper limit is not particularly limited and may be high, but it may be 10 W / m · K or less. The measurement temperature is 25 ° C.

  Moreover, the viscosity at 25 degrees C of a heat conductive silicone composition is 30-800 Pa.s at the time of rotation speed 10 measurement by a spiral viscometer, and 30-600 Pa.s is preferable.

[Cured product]
When the silicone composition is curable, the method of curing the silicone composition is not limited. For example, a method of molding the silicone composition and leaving it at room temperature, heating to 40 to 200 ° C. after molding the silicone composition The silicone elastomer molded article is obtained. Also, the properties of the silicone rubber obtained in this way are not limited, but examples include gel-like, low-hardness rubber-like, or high-hardness rubber-like. The cured thickness is preferably 150 μm or more. The upper limit is not particularly limited, but in consideration of the size of the heat-generating electronic component using the present composition, 5 mm or less is preferable. In addition, the hardness of hardened | cured material poured the silicone composition into the shaping | molding die used as 6 mm hardening thickness, and was made to harden | cure at 100 degreeC for 1 hour. Next, when 2 sheets of hardened | cured material of 6 mm thickness are accumulated and it measures with an Asker C hardness meter, 3-90 are preferable and 5-80 are more preferable.

The thermal conductivity of the cured product at 150 ° C. is preferably 4.0 W / m · K or more, more preferably 4.0 to 6.5, in a hot disk method in accordance with ISO 22007-2. Furthermore, the thermal conductivity of the cured product at 25 ° C. is 5.5 W / m · K or more, more preferably 6.0 W / m · K or more in a hot disk method in accordance with ISO 22007-2. The upper limit is not particularly limited and may be high, but it may be 10 W / m · K or less. The term “at 150 ° C.” at 25 ° C. refers to the measurement temperature, and by having the above-described thermal conductivity at 150 ° C., a material excellent in thermal conductivity at high temperature can be obtained.
Moreover, when making a horizontal axis into temperature and setting a vertical axis | shaft to thermal conductivity, the thermal conductivity estimated from each temperature is also obtained in the linear line obtained by plotting the thermal conductivity obtained by 25 degreeC and 150 degreeC It is covered by the present invention.

  EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following formulae, Me is a methyl group.

The components used in Examples and Comparative Examples are shown below.
First, the following components were prepared.
(A) Component A-1: dimethylpolysiloxane A-2 having a viscosity of 400 mPa · s at 25 ° C., both ends blocked with a dimethylvinylsilyl group, and a Vi group content of 0.018 moL / 100 g: Shin-Etsu Chemical Industrial manufactured KF-54, Molecular weight both ends trimethylsiloxy group blocked dimethyl siloxane / diphenyl siloxane copolymer A-3 having specific gravity (25 ° C.) and dynamic viscosity (25 ° C.) 400 mm ² / s: Shin-Etsu Chemical Industrially manufactured KF-50-1,000 cs, specific gravity (25 ° C.) is 1.00, and kinematic viscosity (25 ° C.) is 1,000 mm ² / s Molecular chain both terminal trimethylsiloxy group-blocked dimethyl siloxane / diphenyl siloxane copolymer

(B) Component Spherical aluminum oxide having the properties shown in the following table

(C) Component Spherical or amorphous aluminum oxide having the properties shown in the following table

(D) Component D-1: Organopolysiloxane represented by the following formula

(E) Component E-1: Spherical glass bead with 99.4% by mass of SiO ₂ content, MIL particle size series M-9 (Maximum central particle diameter is 180 μm) manufactured by Potters Barotini

Ｆ−２：下記式で表されるオルガノハイドロジェンポリシロキサン

Component F-1: Organohydrogenpolysiloxane represented by the following formula

F-2: Organohydrogenpolysiloxane represented by the following formula

(G) component G-1: chloroplatinic acid-1,3-divinyltetramethyldisiloxane complex having a platinum concentration of 1% by mass

(H) Component H-1: 50% solution of 1-ethynyl-1-cyclohexanol in toluene

[Examples 1 to 7, Comparative Examples 1 to 7]
Using the components described above, a silicone composition was prepared by the method shown below, and a thermally conductive molded product was obtained using this silicone composition. Using these, it evaluated by the method shown below. The results are shown in the table.

  The above components were mixed in the amounts shown in Tables 3 and 4 below as follows to obtain a silicone composition. That is, the components (A), (B), (C) and (D) were taken in the amounts shown in the table in a 5-liter gate mixer (product name: 5-liter planetary mixer, manufactured by Inoue Seisakusho Co., Ltd.). Degassed and mixed for 2 hours at ° C. Thereafter, the mixture is cooled to room temperature (25 ° C.), the component (G) is added, and mixing is carried out at room temperature (25 ° C.) to be uniform, then the component (H) is added, and room temperature is made uniform. Mix at (25 ° C.). Further, components (E) and (F) were added, and the mixture was degassed at room temperature to be uniform. With respect to the silicone composition thus obtained, the initial viscosity, the hardness after curing, and the thermal conductivity before and after curing were evaluated by the methods shown below. The results are shown in the table.

[Initial viscosity evaluation]
The initial viscosity of the silicone composition is a value at 25 ° C., and a spiral viscometer: Malcom viscometer (type PC-10AA, rotational speed 10 rpm) was used for the measurement.
[Hardness evaluation after curing]
The silicone composition was poured into a mold having a 6 mm cured thickness and cured at 100 ° C. for 1 hour. Next, two 6 mm thick cured products were stacked and measured with an Asker C hardness tester.
[Thermal conductivity evaluation]
The thermal conductivity before curing of the silicone composition at 25 ° C. was measured using a hot disk method thermal physical property measuring apparatus TPS 2500 S manufactured by Kyoto Electronics Industry Co., Ltd. (Hot disk method according to ISO 22007-2).
Furthermore, the silicone composition was poured into a mold having a cured thickness of 6 mm and cured at 100 ° C. for 1 hour. The thermal conductivity of the cured product at 25 ° C. and 150 ° C. was measured for the obtained 6 mm thick cured product.

Claims (11)

(A) organopolysiloxane,
(B) Spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm ² or less, and an average particle diameter of 50 to 150 μm, and (C) a spherical or irregular particle having an average particle diameter of 0.1 to 5 μm A high thermal conductivity silicone composition comprising shaped aluminum oxide powder,
Blending ratio volume ratio ((B) :( C)) of the above (B) component and (C) component is 5: 5 to 9.5: 0.5, and the total amount of (B) component and (C) component Is 80 to 90% by volume in the composition,
When the thermal conductivity of the composition is 5.5 W / m · K or more and the viscosity of the composition at 25 ° C. is 10 to 30 rpm when measured at a rotational speed of 10 rpm by a spiral viscometer in the hot disk method according to ISO 22007-2. high thermal conductivity silicone composition which is s.   The high thermal conductivity silicone composition according to claim 1, further comprising (D) a silane coupling agent. The component (D) is represented by the following general formula (1)
-SiR ¹ _a (OR ² ) _3-a (1)
(Wherein, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, and a is 0, 1 or 2) is there.)
The high thermal conductivity silicone composition according to claim 2, which is an organopolysiloxane containing at least one silyl group represented by 1 in one molecule and having a viscosity of 0.01 to 30 Pa · s at 25 ° C. Furthermore, spherical glass beads or amorphous glass having a maximum value of (E) central particle diameter of 150 μm or more and an SiO ₂ content of 50% by mass or more is contained at 10% by mass or less based on the total amount of the composition. The high thermal conductivity silicone composition of any one of -3.   The high thermal conductivity silicone composition according to any one of claims 1 to 4, further comprising a curing agent.   The thermally conductive silicone composition according to claim 5, wherein the thermal conductivity of the cured product of the high thermal conductivity silicone composition at 150 ° C is 4.0 W / m · K or more in the hot disk method in accordance with ISO 22007-2. .   7. The high thermal conductivity silicone composition according to claim 6, which is an addition reaction curing type, a condensation reaction curing type or an organic peroxide curing type.   The high thermal conductivity silicone composition according to claim 7, which is addition reaction curable.   A cured product of the high thermal conductivity silicone composition according to any one of claims 5 to 8.   10. The cured product according to claim 9, wherein the thermal conductivity at 150 ° C. is 4.0 W / m · K or more in a hot disk method in accordance with ISO 22007-2. (A) organopolysiloxane,
(B) Spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 hydroxyl groups / nm ² or less, and an average particle diameter of 50 to 150 μm, and (C) a spherical or irregular particle having an average particle diameter of 0.1 to 5 μm The mixing ratio volume ratio ((B) :( C)) of the component (B) to the component (C) including the step of mixing the shape aluminum oxide powder is 5: 5 to 9.5: 0.5, (B The total amount of the component (C) and the component (C) is 80 to 90% by volume in the composition, and the thermal conductivity of the composition is 5.5 W / m · K or more in the hot disc method according to ISO 22007-2. A method for producing a high thermal conductivity silicone composition, wherein the viscosity of the composition at 25 ° C. is 30 to 800 Pa · s when measured at a rotation speed of 10 rpm by a spiral viscometer.