JP2010242022A - Thermally conductive silicone grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermally conductive silicone grease composition excellent in both thermal conductivity and shear resistance. <P>SOLUTION: The thermally conductive silicone grease composition includes at least components (A)-(C). The aggregate amount of the component (B) and (C) accounts for 500-2,000 pts.mass based on 100 pts.mass of the component (A). Component (C)/(component (B)+component (C)) representing a mixed ratio of the component (B) and the component (C) is 0.05-0.5 by mass. Component (A): Organopolysiloxane having a thixotropy index α as defined by η<SB>1</SB>/η<SB>2</SB>of 1.03-1.70, a viscosity at 25°C of 10-1,000,000 mPa s, wherein η<SB>1</SB>is a viscosity as determined at 25°C using a B-type rotational viscometer with a rotor rotation of 6 rpm, and η<SB>2</SB>is a viscosity as determined at 25°C using a B-type rotational viscometer with a rotor rotation of 12 rpm. Component (B): a thermally conductive inorganic filler having a Mohs hardness of ≥6 and an average particle size of 5-20 μm. Component (C): a thermally conductive inorganic filler having a Mohs hardness of ≤5 and an average particle size of 0.5-5 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat conductive silicone grease composition, and more particularly to a heat conductive silicone grease composition having excellent misalignment resistance.

  Generally, since heat is generated during use of electric / electronic parts, heat removal is necessary to operate these parts properly. Conventionally, various heat conductive materials used for heat removal have been used. Proposed. In this case, there are two types of thermally conductive materials: (1) a sheet-like material that is easy to handle, and (2) a paste-like material called heat radiation grease.

  Of these, the sheet-like material (1) has the advantage of being easy to handle and excellent in stability, while the contact thermal resistance is inevitably increased. It will be inferior to the case. In addition, since a certain degree of strength and hardness is required to maintain the sheet shape, tolerances generated between the element and the housing cannot be absorbed, and the element may be destroyed by the stress.

  On the other hand, in the case of the heat radiation grease (2), not only can it be applied to mass production of electrical and electronic products by using a coating device, etc., but also has the advantage of excellent heat radiation performance due to low contact thermal resistance. There is. However, when the viscosity of the heat dissipation grease is lowered to use it in large quantities by screen printing, etc., the result is that the heat dissipation grease shifts due to the thermal shock of the element (pump-out phenomenon), resulting in insufficient heating. The device sometimes malfunctioned.

  Therefore, a specific organopolysiloxane, a thickener such as zinc oxide, alumina, aluminum nitride, boron nitride, and silicon carbide, an organopolysiloxane having at least one hydroxyl group directly bonded to a silicon atom in one molecule, and Grease-like silicone composition in which base oil bleed is suppressed by combining alkoxysilane (Patent Document 1); liquid silicone, thermally conductive inorganic filler having a constant thermal conductivity and a Mohs hardness of 6 or more, and , A thermally conductive silicone composition excellent in thermal conductivity and dispensing properties, comprising a combination of thermally conductive inorganic fillers having a constant thermal conductivity and a Mohs hardness of 5 or less (Patent Document 2); A thermally conductive grease composition comprising a combination of oil and metallic aluminum powder having an average particle size of 0.5 to 50 μm (Patent Document 3); Silicone grease composition in which the filling rate of aluminum nitride in silicone grease is increased by using a mixture of two types of aluminum nitride powders having different average particle diameters (Patent Document 4); and the viscosity of oil is increased. Higher-performance thermal conductive silicone grease compositions such as silicone grease compositions that suppress bleed-out (Patent Document 5) have been proposed, but they are fully compatible with higher performance of electronic and electrical components used. We still haven't got what we can do.

JP 11-49958 A JP-A-11-246884 JP 2000-63873 A JP 2000-169873 A JP2003-301184A

  Accordingly, an object of the present invention is to provide a heat conductive silicone grease composition having excellent thermal conductivity and resistance to misalignment.

  As a result of intensive studies to achieve the above object, the present inventors have determined that two kinds of thermally conductive fillers having different Mohs hardness and particle size range are fixed at a specific ratio in a specific Olga polysiloxane. The present inventors have found that good results can be obtained by combining the amounts of the present invention.

That is, the present invention is a thermally conductive silicone grease composition containing at least the following components (A) to (C), and the total amount of the component (B) and the component (C) is 100 masses of the component (A). (C) component / ((B) component + (C) component), which means a mixing ratio of component (B) and component (C), is 0 to 500 parts by mass. It is a heat conductive silicone grease composition characterized by being 0.05 to 0.5.
Component (A): An organopolysiloxane having a thixotropy α defined by η ₁ / η ₂ of 1.03 to 1.70 and a viscosity at 25 ° C. of 10 to 1,000,000 mPa · s. However, η ₁ is the viscosity when measured at 25 ° C. using a B-type rotational viscometer with a rotor speed of 6 rpm, and η ₂ is the viscosity when measured at 25 ° C. with a rotor speed of 12 rpm. is there.
Component (B): a thermally conductive inorganic filler having a Mohs hardness of 6 or more and an average particle size of 5 to 20 μm.
Component (C): a thermally conductive inorganic filler having a Mohs hardness of 5 or less and an average particle size of 0.5 to 5 μm.

一般式（１）中のＲ³は、メチル基、エチル基、プロピル基などの炭素数１〜６のアルキル基、Ｒ^４は、炭素数１〜２０の飽和又は不飽和の一価炭化水素基からなる群の中から選択される基であり、これらは同一であっても異なっていても良い。又、ｂは５〜１２０の整数である。 The organopolysiloxane of the component (A) needs to contain 1 to 60% by mass of a one-terminal trifunctional hydrolyzable organopolysiloxane represented by the following general formula (1).

R ³ in the general formula (1) is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group or a propyl group, and R ⁴ is a saturated or unsaturated monovalent hydrocarbon group having 1 to 20 carbon atoms. Are groups selected from the group consisting of, and these may be the same or different. B is an integer of 5 to 120.

但し、上式中のＲ^１は、水素原子、又は、炭素数が１〜２０の、飽和又は不飽和の一価炭化水素基の群から選択される少なくとも１種の基であり、ｎ及びｍはそれぞれ１≦ｎ≦１，０００、０≦ｍ≦１，０００である。 In the present invention, the organopolysiloxane other than the one-terminal trifunctional hydrolyzable organopolysiloxane represented by the general formula (2) of the component (A) has at least one alkenyl group in one molecule. It is preferable that it is an organopolysiloxane obtained by addition-reacting an organopolysiloxane represented by the following general formula (2) with a platinum-based catalyst.

However, R ¹ in the above formula is a hydrogen atom or at least one group selected from the group of saturated or unsaturated monovalent hydrocarbon groups having 1 to 20 carbon atoms, and n and m Are 1 ≦ n ≦ 1,000 and 0 ≦ m ≦ 1,000, respectively.

  The component (B) is preferably at least one selected from alumina powder and aluminum nitride powder, and the component (C) is at least selected from zinc oxide powder and aluminum hydroxide powder. One type is preferable.

  The heat-dissipating silicone grease composition of the present invention is not only excellent in thermal conductivity, but also has good misalignment resistance, and is therefore suitable for heat removal from electrical / electronic components that generate heat during use.

The organopolysiloxane of component (A) constituting the heat-dissipating silicone grease composition of the present invention has a thixotropy α defined by η ₁ / η ₂ of 1.03 to 1.70, and at 25 ° C. It is a liquid silicone having a viscosity of 10 to 1,000,000 mPa · s.
Here, η ₁ is the viscosity when measured at 25 ° C. with a B-type rotational viscometer at a rotor speed of 6 rpm, and η ₂ is the viscosity when measured at 25 ° C. with a rotor speed of 12 rpm. It is.

  As described above, the thixotropy of the component (A) is represented by the thixotropy α, and the greater the thixotropy α, the stronger the oil viscosity. In the present invention, the organopolysiloxane (A) is required to have a thixotropy α of 1.03 to 1.70, particularly preferably 1.05 to 1.60. When the thixotropy α is less than 1.03, the viscosity of the oil is small and the affinity between the organopolysiloxane and the heat conductive filler is weak, so that the oil tends to bleed out from the silicone grease composition. On the other hand, when the thixotropy α is greater than 1.70, mixing of the component (A) with the components (B) and (C) becomes difficult.

  In the present invention, the viscosity of the organopolysiloxane of component (A) at 25 ° C. by a B-type rotational viscometer needs to be in the range of 10 to 1,000,000 mPa · s as described above. Is particularly preferably 100 to 100,000 mPa · s. If the viscosity at 25 ° C. is less than 10 mPa · s, the resulting silicone grease composition will have poor stability, and if it is greater than 1,000,000 mPa · s, it is difficult to mix with components (B) and (C). Become.

上記一般式（１）中のＲ³は、メチル基、エチル基、プロピル基などの炭素数１〜６のアルキル基であり、Ｒ^４は、炭素数１〜２０の飽和又は不飽和の一価炭化水素基からなる群の中から選択される基である。これらは同一であっても異なっていても良い。又、ｂは５〜１２０の整数である。 The organopolysiloxane of component (A) needs to contain at least 1 to 60% by mass of a one-terminal trifunctional hydrolyzable organopolysiloxane represented by the following general formula (1).

R ³ in general formula (1) include a methyl group, an ethyl group, an alkyl group having 1 to 6 carbon atoms such as a propyl group, R ⁴ is a monovalent saturated or unsaturated having 1 to 20 carbon atoms It is a group selected from the group consisting of hydrocarbon groups. These may be the same or different. B is an integer of 5 to 120.

上式中のＲ^１は、水素原子、及び炭素数が１〜２０の飽和又は不飽和の一価炭化水素基の群から選択される少なくとも１種の基であり、ｎ及びｍはそれぞれ１≦ｎ≦１，０００、０≦ｍ≦１，０００である。 Organopolysiloxanes other than the one-terminal trifunctional hydrolyzable organopolysiloxane represented by the general formula (1) are not particularly limited, but particularly have at least one alkenyl group in one molecule. Platinum series such as platinum simple substance, chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, etc. containing organopolysiloxane and hydrogen organopolysiloxane having at least two SiH groups represented by the following general formula (2) An organopolysiloxane obtained by addition reaction using a catalyst is preferred.

R ¹ in the above formula is a hydrogen atom and at least one group selected from the group of saturated or unsaturated monovalent hydrocarbon groups having 1 to 20 carbon atoms, and n and m are each 1 ≦ n ≦ 1,000 and 0 ≦ m ≦ 1,000.

  The organopolysiloxane having an alkenyl group may be linear or branched as long as it has at least one alkenyl group directly bonded to a silicon atom in one molecule. Also, a mixture of two or more different viscosities may be used. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-butenyl group, and a 1-hexenyl group, and a vinyl group is preferable from the viewpoint of ease of synthesis and cost.

  Other organic groups bonded to the silicon atom include methyl groups, ethyl groups, propyl groups, butyl groups, hexyl groups, alkyl groups such as dodecyl groups, aryl groups such as phenyl groups, 2-phenylethyl groups, 2-phenylpropoxy groups. In addition to aralkyl groups such as thiol groups, substituted hydrocarbon groups such as chloromethyl groups and 3,3,3, -trifluoropropyl groups are also exemplified. Of these, 90% or more of the organic groups are preferably methyl groups from the viewpoint of ease of synthesis and cost.

  The alkenyl group bonded to the silicon atom may be present at the molecular chain terminal or in the middle of the organopolysiloxane. From the viewpoint of flexibility, it is preferable to exist only at both ends, but some may exist only at one end.

As R ¹ in the hydrogenorganopolysiloxane having at least two Si—H groups represented by the general formula (2), for example, a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, Alkyl groups such as decyl group, dodecyl group, tetradecyl group, hexadecyl group and octadecyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group and allyl group; aryl groups such as phenyl group and tolyl group; Aralkyl groups such as 2-phenylethyl group and 2-methyl-2-phenylethyl group; 3,3,3-trifluoropropyl group, 2- (perfluorobutyl) ethyl group, 2- (perfluorooctyl) ethyl group And halogenated hydrocarbon groups such as p-chlorophenyl group. From the viewpoint of ease of synthesis and cost, 90% or more of R ¹ is preferably a methyl group.

  When obtaining an organopolysiloxane obtained by an addition reaction, which is preferable as an organopolysiloxane other than the one-terminal trifunctional hydrolyzable organopolysiloxane represented by the general formula (1) in the component (A) in the present invention. Two or more types of organopolysiloxanes having alkenyl groups and Si-H groups may be used. Furthermore, dimethylpolysiloxane having no reactive group can be mixed.

As another method, in addition to [R ² ₃ SiO _1/2 ] unit and [R ² ₂ SiO] unit, which are structural units of general linear organopolysiloxane, [R ² SiO _3/2 ] It can also be obtained by introducing units or [SiO _4/2 ] units. Wherein, ^{R 2} is the same as ^{R 1} in the general formula (2).
The method for producing these organopolysiloxanes is not particularly limited. For example, (i) hydrolysis of (CH ₃ ) ₃ SiCl, (CH ₃ ) ₂ SiCl ₂ , (CH ₃ ) SiCl ₃ , etc. Or (ii) this condensate and cyclic low-molecular-weight siloxane are mixed with alkali metal hydroxide, alkali metal silanolate, hydroxide such as tetraalkylphosphonium hydroxide, tetraalkylammonium hydroxide, sulfuric acid, organic In the presence of a catalyst selected from strong acids such as sulfonic acid, the reaction is allowed to equilibrate at room temperature or under heating, or (iii) has a hydroxyl group and comprises (CH ₃ ) ₃ SiO _1/2 units and SiO ₂ units. Organopolysiloxane and polydiorganosiloxane having silanol group can be condensed with amine catalyst or tin catalyst. In the presence of a catalyst, and the like method of reacting at room temperature or under heating.

R ³ in the general formula (1) is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, or a propyl group, and is particularly preferably a methyl group from the viewpoint of ease of synthesis and economy. preferable. R ⁴ is at least one group selected from the group consisting of saturated or unsaturated monovalent hydrocarbon groups having 1 to 20 carbon atoms. Examples of such groups include methyl groups, ethyl groups, propyl groups, hexyl groups, octyl groups, decyl groups, alkyl groups such as dodecyl groups, tetradecyl groups, hexadecyl groups, octadecyl groups; cyclopentyl groups, cyclohexyl groups, etc. Cycloalkyl group; alkenyl group such as vinyl group and allyl group; aryl group such as phenyl group and tolyl group; aralkyl group such as 2-phenylethyl group and 2-methyl-2-phenylethyl group; Examples thereof include halogenated hydrocarbon groups such as trifluoropropyl group, 2- (perfluorobutyl) ethyl group, 2- (perfluorooctyl) ethyl group, and p-chlorophenyl group. From the viewpoint of ease of synthesis and cost, 90% or more of R ⁴ is preferably a methyl group. B is an integer of 5 to 120.

  The content of the one-terminal trifunctional hydrolyzable organopolysiloxane represented by the general formula (1) in the component (A) organopolysiloxane needs to be 1 to 60% by mass. When the content is less than 1% by mass, the compatibility between the components (B) and (C) and the component (A) is deteriorated, and when the content is more than 60% by mass, the shift resistance is deteriorated. In the present invention, the content is particularly preferably 5 to 50% by mass.

  Ingredients (B) and (C) are fillers that impart thermal conductivity to the thermally conductive silicone grease composition of the present invention. In the present invention, the Mohs hardness and average particle size are within a specific range. This is characterized in that the resistance to misalignment is improved. The Mohs hardness referred to here is sometimes referred to as the old Mohs hardness, but is an index representing the hardness of a substance in 10 levels, where the hardness of the hardest diamond is 10.

  The component (B) used in the present invention needs to have a Mohs hardness of 6 or more and an average particle size of 5 to 20 μm. When a heat conductive filler having a Mohs hardness of 5 or less is used, compatibility with the component (C) is deteriorated and high filling cannot be achieved, so that sufficient heat conductivity cannot be imparted. Further, even if the average particle size is smaller than 5 μm or larger than 20 μm, the grease becomes non-uniform and the resistance to misalignment is deteriorated, so that it is particularly preferably 7 to 15 μm.

  Examples of the thermally conductive filler of component (B) include alumina powder, aluminum nitride powder, silicon carbide powder, and the like, and it is particularly preferable to use alumina powder and / or aluminum nitride powder.

  On the other hand, the component (C) is required to have a Mohs hardness of 5 or less and an average particle size of 0.5 to 5 μm, preferably 0.5 to 3 μm. When the Mohs hardness is 6 or more, misalignment resistance deteriorates. Further, even if the average particle size is smaller than 0.5 or larger than 5 μm, high filling cannot be achieved, so that not only sufficient thermal conductivity cannot be obtained, but also grease becomes non-uniform and misalignment resistance is also obtained. Deteriorate.

  Examples of the thermally conductive filler of component (C) include zinc oxide powder, aluminum hydroxide powder, aluminum powder, etc. In the present invention, it is particularly possible to use zinc oxide powder and / or aluminum hydroxide powder. preferable.

  Component (C) / (Component (B) + Component (C)), which means the mixing ratio of component (B) and component (C), is in the range of 0.05 to 0.5 by mass ratio. However, it is preferably 0.1 to 0.3. Even if it is smaller than 0.05 or larger than 0.5, the grease becomes non-uniform so that the displacement resistance is deteriorated.

  On the other hand, the total blending amount of the component (B) and the component (C) needs to be in the range of 500 to 2000 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the component (A), preferably It is the range of 700-1500 mass parts. If it is less than 500 parts by mass, not only a sufficient thermal conductivity cannot be obtained, but also the strength as a grease cannot be maintained, so that it becomes easy to shift. On the other hand, if it is larger than 2000 parts by mass, the grease cannot be maintained.

  In the case of producing the heat conductive silicone grease of the present invention, components (A) to (C) are added, trimix, twin mix, planetary mixer (all are registered trademarks of a mixer manufactured by Inoue Seisakusho Co., Ltd.) Mixing is performed using a mixer such as Ultramixer (registered trademark of mixer manufactured by Mizuho Industry Co., Ltd.), Hibis Disper Mix (registered trademark of mixer manufactured by Special Machine Industries Co., Ltd.), or the like. If necessary, it may be heated to 50-150 ° C.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in full detail, this invention is not limited by this. Tests according to Examples and Comparative Examples conducted for clarifying the superiority of the present invention were performed as follows.

[Grease viscosity]
The viscosity of the thermally conductive silicone grease composition was measured using Model No. PC-1TL (rotation speed: 10 rpm) manufactured by Malcolm Corporation.

〔Thermal conductivity〕
The thermal conductivity was measured at 25 ° C. using TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

〔Particle size〕
The particle diameter is a volume-based cumulative average diameter measured by Microtrac MT3300EX, which is a particle size analyzer manufactured by Nikkiso Co., Ltd.

[Thixotropy]
The thixotropy was defined as α = η ₁ / η ₂ . Here, η ₁ is a viscosity measured at 25 ° C. using a B-type rotational viscometer with a rotor speed of 6 rpm, and η ₂ is a viscosity measured at 25 ° C. with a rotor speed of 12 rpm.

[Displacement]
The deviation of the thermally conductive silicone grease composition was evaluated by numerical values measured according to the following steps.
(1) A 0.5 mm spacer is provided, and a thermally conductive silicone grease composition is sandwiched between an aluminum plate and a glass slide so as to form a circle having a diameter of 1.5 cm.
(2) Next, this test piece is set vertically with respect to the ground, and a thermal shock test manufactured by Espec Co., Ltd. is performed so as to perform a heat cycle test in which -45 ° C. and 150 ° C. (30 minutes each) are alternately repeated. Place in the machine (model number: TSE-11-A) and perform 1000 cycle test.
(3) After the 1000 cycle test, measure how much the thermally conductive silicone grease composition has deviated from its original location.

得られたオルガノポリシロキサンＡ−１中に含有される、加水分解性オルガノポリシロキサンは４４．７質量％に相当する量であった。また、オルガノポリシロキサンＡ−１の２５℃における粘度は下記の通りであり、チキソ度αは１．１２と計算された。
粘度測定結果：
ロータＮｏ．４／６ｒｐｍ：９，５００ｍＰａ・ｓ、
ロータＮｏ．４／１２ｒｐｍ：８，５００ｍＰａ・ｓ [Synthesis Example 1: Synthesis of organopolysiloxane A-1 as component (A)]
A flask with an internal volume of 2000 ml provided with a stirrer, a thermometer, a cooling pipe and a nitrogen gas introduction pipe was sealed at both ends with dimethylvinylsilyl groups, 5 mol% of the main chain was phenyl groups, and the remaining 95 mol% was methyl. 550 g of origanopolysiloxane having a viscosity of 700 mPa · s at 25 ° C., 6.0 g of hydrogen organopolysiloxane of the following [Chemical Formula 1] and 450 g of hydrolyzable organopolysiloxane of [Chemical Formula 2] It was. Furthermore, after adding 0.25 g of a dimethylpolysilyl end-capped dimethylpolysiloxane solution of platinum-divinyltetramethyldisiloxane complex (platinum catalyst containing 1% by mass of platinum atom), the mixture was stirred at 120 ° C. for 1 hour. Organopolysiloxane A-1 was obtained.

The hydrolyzable organopolysiloxane contained in the obtained organopolysiloxane A-1 was an amount corresponding to 44.7% by mass. Moreover, the viscosity at 25 degrees C of organopolysiloxane A-1 was as follows, and thixotropy (alpha) was calculated with 1.12.
Viscosity measurement results:
Rotor No. 4/6 rpm: 9,500 mPa · s,
Rotor No. 4/12 rpm: 8,500 mPa · s

[Synthesis Example 2: Synthesis of Organopolysiloxane A-2 as Component (A)]
Organopolysiloxane A-2 was obtained in the same manner as in Synthesis Example 1 except that the amount of hydrolyzable organopolysiloxane of [Chemical Formula 2] used in Synthesis Example 1 was changed to 60 g. The amount of hydrolyzable organopolysiloxane contained in the obtained organopolysiloxane A-2 was an amount corresponding to 9.7% by mass. Moreover, the viscosity at 25 degrees C of organopolysiloxane A-2 was as follows, and the thixotropy (alpha) was calculated with 1.55.
Viscosity measurement results:
Rotor No. 4/6 rpm: 72,000 mPa · s,
Rotor No. 4/12 rpm: 6,500 mPa · s

[Synthesis of base oil X]
3,000 g of water was placed in a 5 liter flask equipped with a stirrer, a thermometer, a condenser and a dropping device, and a mixture of 490 g of trimethylchlorosilane, 560 g of dimethyldichlorosilane and 650 g of methyltrichlorosilane was added thereto while stirring. The reaction mixture was added dropwise over 3 hours while cooling so that the temperature of the reaction product was 50 ° C. or lower. Next, the mixture was further stirred at 30 ° C. for 2 hours, and the aqueous layer (hydrochloric acid and water) was separated. Then, 1700 g of 3% aqueous sodium carbonate solution was added to the organic layer, and the mixture was stirred at room temperature for 2 hours. The aqueous layer was separated and removed, and 70 g of anhydrous sodium sulfate was added to the remaining organic layer and stirred at room temperature for 3 hours, followed by filtration to obtain a colorless and transparent base oil X having a viscosity of 14 mPa · s.

[Synthesis Example 3: Synthesis of organopolysiloxane A-3 as component (A)]
Into a 500 ml flask equipped with a stirrer, thermometer, cooling pipe and nitrogen gas introduction pipe, 10 g of the obtained base oil X, 22 g of tridimethylsilyl end-capped polydimethylsiloxane having a viscosity of 10 mPa · s, and octamethylcyclotetra 300 g of siloxane was added and heated to 120 ° C. with nitrogen gas being passed. Next, 0.3 g of potassium hydroxide was added, the temperature was further raised to 150 ° C., stirred for 4 hours, cooled to 100 ° C., 2 g of ethylene chlorohydrin was added, and unreacted low molecular siloxane was removed. An organopolysiloxane was obtained.
A hydrolyzable organopolysiloxane of [Chemical Formula 2] was mixed with the obtained organ polysiloxane so that the content was 10% by mass to obtain organopolysiloxane A-3.
The obtained organopolysiloxane A-3 had the following viscosity at 25 ° C., and the thixotropy α was calculated to be 1.33.
Viscosity measurement results:
Rotor No. 4/6 rpm: 35,000 mPa · s,
Rotor No. 4/12 rpm: 26,300 mPa · s

[Synthesis Example 4: Synthesis of Organopolysiloxane A-4 as Component (A)]
The organopolysiloxane synthesized under the same conditions as in Synthesis Example 3 except that the amount of base oil X used as a raw material in Synthesis Example 3 was 25 g and the amount of octamethylcyclotetrasiloxane used was 308 g. The hydrolyzable organopolysiloxane of the above [Chemical Formula 2] was mixed so as to be 5% by mass to obtain organopolysiloxane A-4.
The viscosity of the obtained organopolysiloxane A-4 at 25 ° C. was as follows, and the thixotropy α was calculated to be 1.05.
Viscosity measurement results:
Rotor No. 4/6 rpm: 22,000 mPa · s,
Rotor No. 4/12 rpm: 2,100 mPa · s

得られたオルガノポリシロキサンＡ−５の２５℃における粘度は下記の通りであり、チキソ度αは１．９６と計算された。
粘度測定結果：
ロータＮｏ．４／６ｒｐｍ：９２，０００ｍＰａ・ｓ、
ロータＮｏ．４／１２ｒｐｍ：４７，０００ｍＰａ・ｓ [Synthesis Example 5: Synthesis of Organopolysiloxane A-5 as Component (A)]
500 g of dimethylpolysiloxane having both ends blocked with dimethylvinylsilyl groups and having a viscosity of 600 mPa · s at 25 ° C. and 33 g of hydrogenorganopolysiloxane shown in [Chemical Formula 3] used in Synthesis Example 1 4] and organohydrosiloxane A in the same manner as in Synthesis Example 1 except that 23 g of the hydrogenated organopolysiloxane shown in [4] and 50 g of the hydrolyzable organopolysiloxane shown in [Chemical Formula 2] were charged. -5 was obtained.

The viscosity of the obtained organopolysiloxane A-5 at 25 ° C. was as follows, and the thixotropy α was calculated to be 1.96.
Viscosity measurement results:
Rotor No. 4/6 rpm: 92,000 mPa · s,
Rotor No. 4/12 rpm: 47,000 mPa · s

Synthesis Example 6 Synthesis of Component (A) Organopolysiloxane A-6
Organopolysiloxane was obtained under the same conditions as in Synthesis Example 3 except that 100 g of base oil X used as a raw material in Synthesis Example 3 and 200 g of octamethylcyclotetrasiloxane were used. The resulting organopolysiloxane was mixed with the hydrolyzable organopolysiloxane represented by [Chemical Formula 2] so that the content was 5% by mass to obtain organopolysiloxane A-6.
The viscosity of the resulting organopolysiloxane A-6 at 25 ° C. was as follows, and the thixotropy α was calculated to be 1.02.
Viscosity measurement results:
Rotor No. 4/6 rpm: 440 mPa · s,
Rotor No. 4/12 rpm: 430 mPa · s

[Manufacture of silicone grease composition for heat dissipation]
Six types of organopolysiloxanes A1 to A6 obtained in Synthesis Examples 1 to 6 and dimethylpolysiloxane A-7 represented by the following [Chemical Formula 5] having the following viscosity and a thixotropy α of 1.01 The organopolysiloxane was used. It mix | blends with the component composition shown in [Table 1] and [Table 2], it mixes for 1 hour at 120 degreeC using a planetary mixer (Inoue Seisakusho Co., Ltd. product), Examples 1-9 and Comparative Examples 1-12 A silicone composition for heat dissipation was obtained.
Viscosity measurement result of dimethylpolysiloxane A-7:
Rotor No. 4/6 rpm: 9,800 mPa · s,
Rotor No. 4/12 rpm: 9,700 mPa · s

In addition, the component (B) and component (C) in a table | surface are as follows.
Ingredient (B):
B-1: Alumina powder (average particle size 10.3 μm)
B-2: Alumina powder (average particle size 14.5 μm)
B-3: Aluminum nitride powder (average particle size 10.1 μm)
B-4: Alumina powder (average particle size 1.1 μm)
B-5: Alumina powder (average particle size 30 μm)
Ingredient (C)
C-1: Zinc oxide powder (average particle size 1.1 μm)
C-2: Aluminum hydroxide powder (average particle size 2.1 μm)
C-3: Aluminum hydroxide powder (average particle size 0.4 μm)
C-4: Aluminum hydroxide powder (average particle size 10 μm)

The results in Tables 1 and 2 demonstrate that the heat-dissipating silicone grease composition of the present invention is excellent not only in heat conductivity but also in resistance to misalignment.

  The heat-dissipating silicone grease composition of the present invention is not only excellent in thermal conductivity, but also has good misalignment resistance, and is therefore suitable for heat removal from electrical / electronic components that generate heat during use.

Claims (5)

A thermally conductive silicone grease composition containing at least the following components (A) to (C), wherein the total amount of the component (B) and the component (C) is 500 parts per 100 parts by mass of the component (A): And (C) component / ((B) component + (C) component), which means a mixing ratio of the component (B) and the component (C), is 0.05 to 0. A thermally conductive silicone grease composition characterized in that it is 5;
Component (A): An organopolysiloxane having a thixotropy α defined by η ₁ / η ₂ of 1.03 to 1.70 and a viscosity at 25 ° C. of 10 to 1,000,000 mPa · s. However, η ₁ is the viscosity when measured at 25 ° C. with a B-type rotational viscometer at a rotor speed of 6 rpm, and η ₂ is the viscosity when measured at 25 ° C. with a rotor speed of 12 rpm. is there.
Component (B): a thermally conductive inorganic filler having a Mohs hardness of 6 or more and an average particle size of 5 to 20 μm.
Component (C): a thermally conductive inorganic filler having a Mohs hardness of 5 or less and an average particle size of 0.5 to 5 μm. The organopolysiloxane of the said component (A) contains 1-60 mass% of components which are the hydrofunctional organopolysiloxane of the one terminal trifunctional represented by following General formula (1). Thermally conductive silicone grease composition;

However, R ³ in the general formula (1) is an alkyl group having 1 to 6 carbon atoms, R ⁴ is selected from the group consisting of monovalent saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms Groups, which may be the same or different. B is an integer of 5 to 120. Organopolysiloxane other than the one-terminal trifunctional hydrolyzable organopolysiloxane represented by the general formula (1) in the component (A) has at least one alkenyl group in one molecule. The thermally conductive silicone grease according to claim 1 or 2, which is an organopolysiloxane obtained by addition reaction of an organohydrogenpolysiloxane represented by the following general formula (2) with a platinum-based catalyst: Composition;

However, R ¹ in the formula is a hydrogen atom or at least one group having a carbon number of 1 to 20, selected from the group of monovalent saturated or unsaturated hydrocarbon group, n and m Are 1 ≦ n ≦ 1,000 and 0 ≦ m ≦ 1,000, respectively.
  The thermally conductive silicone composition according to any one of claims 1 to 3, wherein the component (B) is at least one selected from alumina powder and aluminum nitride powder.   The thermally conductive silicone composition according to any one of claims 1 to 4, wherein the component (C) is at least one selected from zinc oxide powder and aluminum hydroxide powder.