JP2006188549A - Addition reaction-curable type silicone gel composition, thermoconductive silicone composition and radiation sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an addition reaction-curable type silicone gel composition regulating the viscosity elevation of the composition for maintaining its flowing property even on highly filling a thermoconductive filler without performing the surface treatment of the filler and having a good working property. <P>SOLUTION: This addition reaction-curable type silicone gel composition contains (A) 100 pts.wt. alkenyl group-containing organopolysiloxane having 500-2,000 ppm content of hydroxy group bonding with a silicon atom, (B) an organohydrogenpolysiloxane having in average ≥2 hydrogen atoms each bonding with a silicon atom in one molecule by an amount becoming 0.1-1.5 mole hydrogen atom bonded with the silicon atom based on 1 mol of the alkenyl group in the (A) component, (C) 2-100 pts.wt. organopolysiloxane having 2- or 3-functional hydrolyzable groups in one side of its terminals, and (D) an effective amount of a platinum catalyst. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermally conductive silicone composition obtained by blending a thermally conductive filler with an addition reaction curable silicone gel composition and a heat dissipation sheet obtained by curing the thermally conductive silicone composition.

  Conventionally, heat-generating components such as power transistors and ICs deteriorate in characteristics due to the generation of heat. For example, a heat sink is attached to dissipate heat. At this time, a heat radiating sheet is provided between the heat-generating component and the heat sink, so that heat is efficiently radiated while ensuring electrical insulation.

  This heat radiating sheet is obtained by curing a heat conductive silicone composition. As such a heat conductive silicone composition, Patent Document 1 discloses an organopolysiloxane containing a silicon atom-bonded alkenyl group, an organohydrogenpolysiloxane containing a silicon atom-bonded hydrogen atom, a heat conductive filler, and platinum. Thermally conductive silicone compositions having a catalyst and a methylpolysiloxane containing hydrolyzable groups are described.

Patent Document 2 describes a thermally conductive silicone composition containing silicone oil as a main ingredient and alumina powder as a filler.
JP 2003-213133 A JP 2004-161797 A

  However, the thermally conductive silicone composition described in Patent Document 1 or 2 requires a surface treatment of the thermally conductive filler. That is, when the heat conductive filler is highly filled in order to increase the heat conductivity, there is a problem that the viscosity of the resulting composition is rapidly increased and the fluidity is lowered. In order to deal with such problems, surface treatment has been performed when the thermally conductive filler is blended.

  The present invention has been made in order to cope with such problems, and even if the heat conductive filler is highly filled without surface treatment, the increase in the viscosity of the composition is suppressed, and the handling workability at the time of molding processing is suppressed. Addition reaction curable silicone gel composition, addition reaction curable silicone gel composition obtained by blending a heat conductive filler in the addition reaction curable silicone gel composition, and a heat dissipation sheet obtained by curing the composition The purpose is to provide.

  The addition reaction curable silicone gel composition of the present invention comprises (A) 100 parts by weight of an alkenyl group-containing organopolysiloxane having an amount of hydroxyl groups bonded to silicon atoms of 500 to 2000 ppm, and (B) an average of 2 or more per molecule. Organohydrogenpolysiloxane having a hydrogen atom bonded to the silicon atom of the component (A) The hydrogen atom bonded to the silicon atom of this component is 0.1 to 1.5 mol with respect to 1 mol of the alkenyl group in the component (A). (C) 2 to 100 parts by weight of an organopolysiloxane having a bifunctional or trifunctional hydrolyzable group at one end, and (D) an effective amount of a platinum catalyst.

  In general, an addition reaction type silicone composition utilizing hydrosilylation includes an alkenyl group-containing organopolysiloxane which is a base polymer of component (A), an organohydrogenpolysiloxane which is a crosslinking agent of component (B), and (D) curing. As is well known to have a platinum catalyst as a catalyst, the addition reaction curable silicone gel composition of the present invention is a piece which is a component (C) by introducing a specific amount of hydroxyl group into the component (A). It is characterized by blending an organopolysiloxane having a bifunctional or trifunctional hydrolyzable group at the terminal.

  A heat conductive silicone composition is obtained by mix | blending the heat conductive filler of (E) component with the addition reaction curable silicone gel composition obtained in this way.

  Moreover, a heat radiating sheet can be obtained by curing the thermally conductive silicone composition.

  The addition reaction curable silicone gel composition of the present invention and the heat conductive silicone composition obtained by blending the addition reaction curable silicone gel composition with a heat conductive filler do not undergo surface treatment of the heat conductive filler. Even if it is highly filled, the increase in viscosity is suppressed, the fluidity is maintained, and excellent moldability is obtained.

  Moreover, according to the heat radiating sheet of the present invention obtained by curing the thermally conductive silicone composition, high thermal conductivity filler filling is possible, so that the thermal conductivity can be improved.

Hereinafter, the present invention will be described in detail.
[(A) component]
(A) A component is the main ingredient of this composition. The molecular structure is not limited, and examples thereof include linear, cyclic, branched, and partially branched linear.

  The component (A) contains an average of 0.1 or more silicon atom-bonded alkenyl groups in one molecule. Preferably, an alkenyl group bonded to an average of 0.8 or more, more preferably an average of 2 or more silicon atoms per molecule is contained in one molecule. Further, the number of alkenyl groups in one molecule is usually 20 or less, and preferably about 10 or less. When the average value of silicon-bonded alkenyl groups in one molecule is less than the lower limit of the above range, the resulting composition may not be sufficiently cured, and when the upper limit of the above range is exceeded, the resulting cured product This is because the physical properties of the physical properties may deteriorate.

  In addition, it is preferable that content of this alkenyl group shall be 0.01-20 mol% of all the organic groups couple | bonded with the silicon atom in 1 molecule, especially 0.1-10 mol%. In addition, the alkenyl group may be bonded to the silicon atom at the end of the molecular chain, may be bonded to the silicon atom in the middle of the molecular chain, or may be bonded to the both, the curing rate of the composition, From the viewpoint of physical properties of the cured product, it is preferable that it is bonded to at least silicon atoms at the molecular chain terminals, particularly silicon atoms at both molecular chain terminals. Examples of the alkenyl group include those having usually 2 to 8 carbon atoms, preferably about 2 to 6 carbon atoms, such as vinyl group, allyl group, butenyl group, pentenyl group, and hexenyl group. A vinyl group is preferred.

  Furthermore, (A) component has a hydroxyl group couple | bonded with a silicon atom, and it is preferable that the amount of the hydroxyl groups is 500-2000 ppm. If it is less than 500 ppm, effects such as fluidity improvement cannot be obtained sufficiently, and if it exceeds 2000 ppm, adverse effects such as a decrease in the curing rate, foaming of the cured product, and deterioration in heat resistance occur. By introducing such a specific small amount of hydroxyl groups, the fluidity of the present composition is increased and high filling of the filler is enabled. As a method for quantifying the amount of such a hydroxyl group, for example, the KF method (Karl Fischer method) is preferable. However, when performing this measurement method, it is necessary to dehydrate (A) component beforehand.

  Examples of the component (A) silicon-bonded organic group other than the alkenyl group (that is, an unsubstituted or substituted monovalent hydrocarbon group bonded to a silicon atom other than the alkenyl group) include, for example, a methyl group, an ethyl group, and a propyl group Alkyl groups such as cyclopentyl group, cyclohexyl groups such as cyclohexyl group, aryl groups such as phenyl group, tolyl group, xylyl group, or halogenated carbons in which these hydrogen atoms are partially substituted by chlorine atoms, fluorine atoms, etc. Examples of such as a hydrogen group usually include those having 1 to 12 carbon atoms, preferably about 1 to 8 carbon atoms, preferably an alkyl group and an aryl group, more preferably a methyl group, It is a phenyl group.

Component (A) is, for example, a cyclic siloxane such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, tetravinyltetramethylcyclotetrasiloxane, R ¹ ₃ SiO _1/2 (R ¹ is a monovalent hydrocarbon group) It is obtained by carrying out equilibration polymerization of an organosiloxane having units and water with an appropriate catalyst such as an alkali or acid, followed by a neutralization step and a step of removing excess low-molecular siloxane. Alternatively, after the neutralization step without adding water during the equilibration polymerization, the excess low molecular siloxane content is removed, and the organic group is thermally deteriorated by heating for a certain time under oxygen.

  (A) The viscosity in 25 degreeC of a component is 50-2000 mPa * s, Preferably, it is 100-1000 mPs * s. This is because when the viscosity at 25 ° C. is less than the lower limit of the above range, physical properties of the obtained cured product, for example, physical properties such as hardness tend to be remarkably lowered, while the upper limit of the above range is exceeded. It is because the handling operation of a composition will fall remarkably when it exceeds.

[Component (B)]
The component (B) reacts with the component (A) and acts as a crosslinking agent. The molecular structure is not particularly limited, and for example, a linear, cyclic, branched, or three-dimensional network structure can be used. Further, it is necessary to have an average of 2 or more hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule, and it is desirable to have 2 to 200 SiH groups, more preferably 3 to 100 SiH groups. . As the component (B), an average composition formula:
R ² _b H _c SiO _{{4- (b + c)} / 2}
What is shown by is used.

In the formula, R ² is an unsubstituted or substituted monovalent hydrocarbon group preferably having 1 to 10 carbon atoms, excluding an aliphatic unsaturated bond, and as R ² , Examples thereof include the same as those exemplified as the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom excluding the alkenyl group, preferably an alkyl group or an aryl group, more preferably a methyl group or a phenyl group. It is a group. B is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0. Preferably, b is 1.0 to 1.0. 2.0 and c are 0.01 to 1.0, and b + c is 1.5 to 2.5.

  The SiH group contained in at least 2, preferably 3 or more in one molecule may be located at either the molecular chain end or in the middle of the molecular chain, or may be located at both of them. The number (or polymerization degree) of silicon atoms in one molecule is usually 2 to 300, preferably about 4 to 150, and the viscosity at 25 ° C. is usually 1 to 100,000 Pa · s, Preferably, a liquid is used at room temperature (25 ° C.) of about 1 to 5,000 Pa · s.

  Examples of the component (B) include 1,1,3,3-tetramethyldisiloxane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, and trimethylsiloxy group-blocked methylhydrogen at both ends. Examples thereof include polysiloxane, a trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer, and a both-end dimethylhydrogensiloxy group-capped dimethylpolysiloxane.

  Component (B) can be obtained by a known production method. For example, octamethylcyclotetrasiloxane and / or tetramethylcyclodisiloxane and a compound containing 1,1'-dihydro-2,2 ', 3,3'-tetramethyldisiloxane units that can be terminal groups Can be easily obtained by equilibrating at a temperature of about −10 to + 40 ° C. in the presence of a catalyst such as sulfuric acid, trifluoromethanesulfonic acid or methanesulfonic acid.

  Component (B) is blended in an amount of 0.1 to 1.5 moles of hydrogen atoms (SiH groups) bonded to silicon atoms in this component with respect to 1 mole of silicon-bonded alkenyl groups in component (A). This is the amount. This is because if the amount is less than 0.1 mol, the resulting composition will not be sufficiently cured, and if it exceeds 1.5 mol, the heat dissipation sheet obtained by curing the composition will be hard.

[Component (C)]
The component (C) is a component that imparts the characteristics of the present composition that makes it easy to handle and mold even if the heat conductive filler of the component (E) is blended in a large amount. In addition, one end represented by the following general formula is a trifunctional or bifunctional hydrolyzable group-containing polyorganosiloxane, thereby further increasing the effect of reducing the viscosity of the composition.

Here, R ³ is a monovalent hydrocarbon group that does not have the same or different aliphatic unsaturated bond, and examples thereof include alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group. R ⁴ is an alkoxy group having 1 to ⁴ carbon atoms or an acyloxy group, and examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and an acetoxy group. R ⁵ is an oxygen atom or a divalent hydrocarbon group, and examples of the divalent hydrocarbon group for R ⁵ include alkylene groups such as a methylene group, an ethylene group, a propylene group, and an isopropylene group. In particular, R ⁵ is preferably an oxygen atom. d is an integer of 2 or 3, preferably 3. Moreover, p in the above formula is an integer of 200 to 500, preferably an integer of 200 to 300. If p in the above formula is less than the lower limit of the range, the component (E) may bleed from the cured composition, whereas if it exceeds the upper limit of the range, the component (E) This is because the molecular volume constrained on the surface of the resin increases so much that the component (E) cannot be blended in a large amount.

Although the typical example of (C) component is shown below, this invention is not limited to this.

  Component (C) can be obtained by the following method. For example, the organopolysiloxane represented by the above formula (I) is an alkoxy-exchange of a silanol group-containing silicone oil and an alkoxysilane compound having at least three silicon-bonded alkoxy groups in the molecule under an acid catalyst such as acetic acid. It can be obtained by a reaction method. The organopolysiloxane represented by the above formula (II) includes a one-end hydrogen group-containing silicone oil, an alkoxysilane compound having at least two silicon atom-bonded alkoxy groups and one silicon atom-bonded alkenyl group in the molecule, Can be obtained by a method of addition reaction in the presence of a platinum catalyst.

  (C) The compounding quantity of a component is 2-100 weight part with respect to 100 weight part of (A) component, Preferably, it is 10-50 weight part. If the blending amount is too small, the effect of lowering the viscosity and plasticity of the composition is reduced, and if it is too much, the physical properties of the cured product are decreased.

[(D) component]
The component (D) is a curing catalyst for obtaining a cured product by reacting the vinyl group of the component (A) with the hydrogen group of the component (B). Examples of the component (D) include chloroplatinic acid, platinum olefin complex, platinum vinylsiloxane complex, platinum phosphorus complex, platinum alcohol complex, platinum black, and the like.

  (D) The compounding quantity of a component is a quantity used as 0.1-1000 ppm as a platinum element with respect to (A) component. If the content is less than 0.1 ppm, the resulting composition will not be sufficiently cured. On the other hand, even if it exceeds 1000 ppm, no improvement in the curing rate can be expected.

  From the above components (A) to (D), the addition reaction curable silicone gel composition of the present invention is constituted. The method for curing the present composition is not limited, and examples thereof include a method in which the present composition is molded and then allowed to stand at room temperature, and a method in which the composition is molded and then heated to 50 to 200 ° C. Thus, the property of the cured product of the present composition is a soft gel.

  Further, the penetration of the cured product is preferably in the range of 20 to 150. Here, the penetration is measured by a 1/4 cone defined by ASTM D1403.

  A heat conductive silicone composition is obtained by mix | blending the heat conductive filler which is (E) component with this addition reaction hardening type silicone gel composition.

  [Component (E)] The component (E) is a component that imparts thermal conductivity to the composition. As the thermally conductive filler, various metal powders having thermal conductivity can be used.

  Examples of the component (E) include metal powders such as aluminum powder, copper powder, silver powder, and nickel powder, metal oxides such as alumina powder, magnesium oxide powder, beryllium oxide powder, chromium oxide powder, and titanium oxide powder. Examples thereof include metal nitride powders such as powder, boron nitride powder and aluminum nitride powder, and metal carbide powders such as boron carbide powder, titanium carbide powder and silicon carbide powder. In particular, alumina powder and silicon carbide powder are preferable.

  (E) It is preferable that the average particle diameter of a component is 0.1-100 micrometers, especially 0.1-40 micrometers. If the average particle size is too large, the dispersibility deteriorates, and in the case of liquid silicone rubber, the heat conductive filler may settle if left as it is. The component (E) is composed of a heat conductive filler powder having a large average particle size (specifically, an average particle size of 5 to 40 μm) and a heat conductive filler powder having a small average particle size (specifically, an average particle size). A mixture with a diameter of 0.1 to 3 μm), which improves the filling efficiency and enables low viscosity and high thermal conductivity.

  In addition, examples of the shape of the component (E) include a spherical shape, a needle shape, a disc shape, a rod shape, a flat shape, and an indefinite shape.

  (E) The compounding quantity of a component is 500-2000 weight part with respect to 100 weight part of compositions which consist of said (A)-(D) component. (E) It is because the thermal conductivity of the heat conductive silicone composition obtained as the compounding quantity of a component is less than the lower limit of the said range tends to become inadequate, On the other hand, when the upper limit of the said range is exceeded. The viscosity of the obtained heat conductive silicone composition becomes too high, and the component (E) cannot be uniformly dispersed in the resulting composition, and the handling workability tends to be significantly reduced. Because there is.

  Further, as other optional additive components, for example, vinyl group-containing organopolysiloxanes such as methylvinylcyclotetrasiloxane, triallyl isocyanurate, acetylene alcohol for the purpose of adjusting the curing speed and storage stability of the composition in the addition reaction. And siloxane-modified products thereof. Further, reinforcing silica, colorant, heat resistance improver such as iron oxide and cerium oxide, and adhesion assistant to the extent that the effects of the present invention are not impaired may be added. In addition, the addition amount of these arbitrary components can be made into a normal amount in the range which does not inhibit the effect of this invention.

  As mentioned above, the heat conductive silicone composition of this invention is comprised from (A)-(E) component. The viscosity at 23 ° C. of the thermally conductive silicone composition part thus obtained is preferably 10 to 100 Pa · S. This is because if it is less than the lower limit of the above range, the moldability deteriorates. On the other hand, if it exceeds the upper limit of the above range, the fluidity decreases and good handling workability cannot be maintained.

  The heat dissipation sheet of the present invention can be obtained by curing the thermally conductive silicone composition. The method for curing the heat conductive silicone composition is not particularly limited, and examples thereof include a method in which the heat conductive silicone composition is formed into a sheet by calender molding and then heated to 50 to 200 ° C.

  Further, a glass cloth, a cloth made of polyester, nylon, etc., a non-woven fabric, a resin film made of polyimide, nylon, polyester, or the like may be put inside the heat dissipation sheet for reinforcement. Thereby, the strength of the heat radiating sheet is improved and the expansion of the heat radiating sheet is suppressed, so that it becomes easy to handle and workability is improved.

  The addition reaction curable silicone gel composition and the heat conductive silicone composition of the present invention will be described in detail with reference to examples. In the synthesis examples, examples and comparative examples, all parts represent parts by weight. The characteristics in the examples and comparative examples are values measured at 23 ° C., and the characteristics were measured as follows.

[Penetration of cured product of addition reaction curable silicone gel composition]
Measured based on JIS K 6249. Specifically, a cured product of an addition reaction curable silicone gel composition before blending with a heat conductive filler (alumina) was prepared under the curing conditions of 150 ° C. × 1 hour, and ASTM D1403 (1/4 cone) was used. The penetration was measured.

[Viscosity of thermally conductive silicone composition]
Based on JIS K 6249, the viscosity of the heat conductive silicone composition was measured.

[Synthesis Example 1]
In a flask equipped with a stir bar and a condenser tube, 4000 parts of octamethylcyclotetrasiloxane, 50 parts of divinyltetramethylsiloxane, and 1.8 parts of water are charged, and equilibration polymerization is carried out at 150 ° C. for 5 hours using a KOH catalyst. did. Thereafter, phosphoric acid was added for neutralization. Further, the low molecular weight siloxane component was removed under reduced pressure to obtain a polyorganosiloxane containing a vinyl group and a hydroxyl group. This polyorganosiloxane had a viscosity of 540 mPa · s at 25 ° C., and after dehydration, the amount of hydroxyl group measured by the Karl Fischer method (KF method) was 800 ppm. In addition, the measurement of the amount of hydroxyl groups is a Karl Fischer method automatic moisture measuring device (KF-06 type, manufactured by Mitsubishi Kasei Co., Ltd.) using a KF reagent (Karl Fischer reagent SS, manufactured by API Corporation). As a pretreatment, the amount of water was measured by dissolving in a dehydrated solvent (CM 50 ml and ML 10 ml, manufactured by API Corporation), and the hydroxyl amount was calculated from the amount of water.

[Synthesis Example 2]
A vinylorgano and hydroxyl group-containing polyorganosiloxane was obtained in the same manner as in Synthesis Example 1 except that the amount of water added was 3.0 parts. This polyorganosiloxane had a viscosity of 620 mPa · S at 25 ° C., and the amount of hydroxyl group measured by the KF method after dehydration was 1600 ppm.

[Synthesis Example 3]
A polyorganosiloxane containing a vinyl group and a hydroxyl group was obtained in the same manner as in Synthesis Example 1 except that the amount of water added was 0 parts. This polyorganosiloxane had a viscosity at 25 ° C. of 470 mPa · S, and the amount of hydroxyl group measured by the KF method after dehydration was 50 ppm.

[Synthesis Example 4]
A vinylorgano and hydroxyl group-containing polyorganosiloxane was obtained in the same manner as in Synthesis Example 1 except that the amount of water added was 1.3 parts. This polyorganosiloxane had a viscosity of 500 mPa · S at 25 ° C., and after dehydration treatment, the amount of hydroxyl group measured by the KF method was 400 ppm.

[Example 1]
In 180 parts of the polyorganosiloxane obtained in Synthesis Example 1, Formula 1:
(CH ₃ ) ₃ SiO [Si (CH ₃ ) ₂ O] ₂₅₀ Si (CH ₃ ) ₂ (CH ₂ ) ₂ Si (OCH ₃ ) ₃
20 parts of trimethoxysiloxane having one end represented by the formula: 1.00 parts of methylhydrogenpolysiloxane consisting of 53 mol% of methylhydrogen groups and 47 mol% of dimethyl groups in the side chain at both ends, 1-ethynyl 0.04 part of -1-cyclohexanol and 5 ppm of a vinyl siloxane complex of chloroplatinic acid as platinum elements were added and stirred. 100 parts of the addition reaction curable silicone gel composition thus obtained was transferred to a 3 L universal kneading machine, and 700 parts of amorphous alumina having an average particle diameter of 8 μm was added and kneaded for 10 minutes.

  The viscosity of the heat conductive silicone composition thus obtained was measured with a VDH type rotational viscometer (manufactured by Shibaura System Co., Ltd., rotor No. 7, 20 rpm).

  The addition reaction curable silicone gel composition was also cured to produce a cured product, and the penetration was measured by ASTM D1403 (1/4 cone). The results are shown in Table 1.

[Example 2]
Example 1 except that 60 parts of one-terminal trimethoxysiloxane represented by Formula 1 and 0.88 part of methyl hydrogen polysiloxane of Example 1 were added to 140 parts of the polyorganosiloxane obtained in Synthesis Example 1. As well as. The results are shown in Table 1.

[Example 3]
Example 1 except that 60 parts of one-end trimethoxysiloxane represented by Formula 1 and 0.80 part of methylhydrogenpolysiloxane of Example 1 were added to 140 parts of the polyorganosiloxane obtained in Synthesis Example 2. As well as. The results are shown in Table 1.

[Example 4]
To 140 parts of the polyorganosiloxane obtained in Synthesis Example 1, instead of the one-terminal trimethoxysiloxane represented by Formula 1, Formula 2:
(CH ₃ ) ₃ SiO [Si (CH ₃ ) ₂ O] ₂₂₀ Si (CH ₃ ) ₂ (CH ₂ ) ₂ SiCH ₃ (OCH ₃ ) ₂
The reaction was performed in the same manner as in Example 1 except that 60 parts of dimethoxysiloxane having one terminal and 0.84 part of methyl hydrogen polysiloxane of Example 1 were added. The results are shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was conducted except that 140 parts of the polyorganosiloxane obtained in Synthesis Example 3 was added except for 1.10 parts of methyl hydrogen polysiloxane of Example 1. The results are shown in Table 1.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that 140 parts of the polyorganosiloxane obtained in Synthesis Example 4 was added except for 1.00 part of the methylhydrogen polysiloxane of Example 1. The results are shown in Table 1.

[Comparative Example 3]
Example except that 200 parts of the polyorganosiloxane obtained in Synthesis Example 1 was added with 0 part of one-end trimethoxysiloxane represented by Formula 1 and 1.16 parts of methylhydrogenpolysiloxane of Example 1. 1 was performed. The results are shown in Table 1.

[Comparative Example 4]
To 140 parts of the polyorganosiloxane obtained in Synthesis Example 1, instead of the one-terminal trimethoxysiloxane represented by Formula 1, Formula 3:
(CH ₃ O) ₃ SiO [Si (CH ₃ ) ₂ O] ₂₀₀ Si (OCH ₃ ) ₃
It was carried out in the same manner as in Example 1 except that 60 parts of trimethoxysiloxane at both ends and 0.80 part of methyl hydrogen polysiloxane of Example 1 were added. The results are shown in Table 1.

Claims (8)

(A) 100 parts by weight of an alkenyl group-containing organopolysiloxane having an amount of hydroxyl groups bonded to silicon atoms of 500 to 2000 ppm,
(B) Organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms on average in one molecule. Hydrogen bonded to silicon atoms in this component with respect to 1 mol of alkenyl groups in component (A). An amount of 0.1 to 1.5 moles of atoms,
(C) 2 to 100 parts by weight of an organopolysiloxane having a bifunctional or trifunctional hydrolyzable group at one end;
And (D) an addition reaction curable silicone gel composition having an effective amount of a platinum catalyst.   The addition reaction curable silicone gel composition according to claim 1, wherein the component (A) has an alkenyl group bonded to an average of 0.1 or more silicon atoms in one molecule.   The addition reaction curable silicone gel composition according to claim 1 or 2, wherein the viscosity of the component (A) at 25 ° C is 50 to 2000 mPa · S.   The addition reaction curable silicone gel composition according to any one of claims 1 to 3, wherein the penetration of the cured product is 20 to 150. (A) 100 parts by weight of an alkenyl group-containing organopolysiloxane having an amount of hydroxyl groups bonded to silicon atoms of 500 to 2000 ppm,
(B) Organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms on average in one molecule. Hydrogen bonded to silicon atoms in this component with respect to 1 mol of alkenyl groups in component (A). An amount of 0.1 to 1.5 moles of atoms,
(C) 2 to 100 parts by weight of an organopolysiloxane having a bifunctional or trifunctional hydrolyzable group at one end;
(D) an effective amount of platinum catalyst,
And (E) Thermally conductive filler A thermally conductive silicone composition comprising 500 to 2000 parts by weight with respect to 100 parts by weight of the composition comprising the above components (A) to (D).   The thermally conductive silicone composition according to claim 5, wherein the component (E) is a metal powder.   The heat conductive silicone composition according to claim 5 or 6, wherein the viscosity at 23 ° C is 10 to 100 Pa · s.   A heat-dissipating sheet obtained by molding and curing the thermally conductive silicone composition according to any one of claims 5 to 7 into a sheet shape.