WO2018139506A1

WO2018139506A1 - Thermally conductive polyorganosiloxane composition

Info

Publication number: WO2018139506A1
Application number: PCT/JP2018/002191
Authority: WO
Inventors: 大悟平川; 正則高梨; 坂本　淳
Original assignee: モメンティブ・パフォーマンス・マテリアルズ・ジャパン合同会社
Priority date: 2017-01-27
Filing date: 2018-01-25
Publication date: 2018-08-02
Also published as: CN110234711B; CN110234711A

Abstract

The present invention pertains to a thermally conductive polysiloxane composition that provides a cured material having excellent tack properties and an excellent flexibility. This thermally conductive polysiloxane composition contains (A) a thermally conductive filler, (B) a siloxane compound having an alkoxysilyl group and a straight-chain siloxane structure, (C) a polyorganosiloxane having at least two silicon atom-bonded alkenyl groups in each molecule, (D1) a straight-chain polyorganosiloxane represented by general formula (4), (D2) a polyorganohydrogensiloxane having in each molecule at least three units represented by general formula (5), and (E) a platinum catalyst.

Description

Thermally conductive polyorganosiloxane composition

The present invention relates to a thermally conductive polyorganosiloxane composition.

Electronic components represented by power transistors, ICs, CPUs, and the like use heat conductive grease or a heat conductive sheet with high heat conductivity using silicone in order to prevent heat storage of the heating element. In order to improve the thermal conductivity of silicone, thermal conductive fillers such as silica powder, alumina, boron nitride, aluminum nitride, magnesium oxide are used in combination (Patent Document 1), and the thermal conductive filler is made higher. In order to fill, it is known to subject the thermally conductive filler to surface treatment (Patent Document 2).

On the other hand, there is a demand for a thermally conductive composition having flexibility. In response to such a demand, an organopolysiloxane having at least two alkenyl groups in one molecule, an organohydrogensiloxane having an Si—H group in the side chain, and an organohydrogen having an Si—H group at the terminal An addition reaction curable thermal conductive polysiloxane composition containing an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms in one molecule in combination with siloxane is known (Patent Document 3).

JP 2002-003831 A International Publication No. 2005/030874 JP 2002-327116 A

However, when the organohydrogensiloxane having an Si—H group in the side chain and the organohydrogensiloxane having an Si—H group at the end described in Patent Document 3 are used, flexibility and tackiness are not sufficient. .

An object of the present invention is to provide a thermally conductive polysiloxane composition that gives a cured product excellent in tackiness and flexibility.

The present invention relates to the following.
[1] (A) a thermally conductive filler;
(B) a siloxane compound having an alkoxysilyl group and a linear siloxane structure;
(C) a polyorganosiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule;
(D1) General formula (4):

(Where
R ⁷ is a hydrogen atom,
R ⁸ is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond;
f is 1 to 200)
A linear polyorganohydrogensiloxane represented by:
(D2) General formula (5):
R ⁹ _g R ¹⁰ _h SiO _{({4- (g + h)} / 2)} (5)
(Where
R ⁹ independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond;
R ¹⁰ is a hydrogen atom,
g is an integer from 0 to 2,
h is an integer of 1 or 2,
g + h is an integer of 1 to 3,
(Except when g is 1 and h is 1)
A polyorganohydrogensiloxane having at least three units represented by
(E) A thermally conductive polysiloxane composition comprising a platinum catalyst.
[2] The sum of the number of hydrogen atoms bonded to the silicon atom of (D1) H _D1 and the number of hydrogen atoms bonded to the silicon atom of (D2) H _D2 with respect to the number Vi _C of alkenyl groups in (C) The thermally conductive polysiloxane composition according to [1], wherein the ratio ((H _D1 + H _D2 ) / Vi _C ) of a certain number (H _D1 + H _D2 ) is less than 1.50.
[3] (D2) is composed of R ¹¹ ₂ HSiO _1/2 unit (wherein R ¹¹ has the same meaning as R ⁹ ) and SiO _4/2 unit, and bonded to a silicon atom in one molecule. The heat conductive polysiloxane composition according to [1] or [2], which is a polyorganohydrogensiloxane having 3 or more hydrogen atoms.
[4] The ratio (H _D1 : H _D2 ) of the number H _{D1 of} hydrogen atoms bonded to the silicon atom of (D1) to the number of hydrogen atoms H _D2 bonded to the silicon atom of ( _D2 ) is 9.9: 0. The thermally conductive polysiloxane composition according to any one of [1] to [3], which is 1 to 1: 9.
[5] (B) is represented by the general formula (1):

(Where
R ¹ is a group having an alkoxysilyl group having 1 to 4 carbon atoms,
R ² is a monovalent hydrocarbon group having 6 to 18 carbon atoms or the general formula (2):

(Where
R ⁴ is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms,
Y is a group selected from the group consisting of a methyl group, a vinyl group, and R ¹ ;
d is an integer of 2 to 500)
A linear organosiloxy group represented by
X is independently a divalent hydrocarbon group having 2 to 10 carbon atoms,
a and b are each independently an integer of 1 or more;
c is an integer of 0 or more,
a + b + c is an integer of 4 or more,
R ³ is each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom)
The heat conductive polysiloxane composition according to any one of [1] to [4], which is a siloxane compound represented by the formula:
[6] (C) is represented by the general formula (3):

(Where
R ⁵ is independently an alkenyl group having 2 to 6 carbon atoms,
R ⁶ is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms,
e is a linear polyorganosiloxane having a viscosity at 23 ° C. of 0.01 to 50 Pa · s), and the thermally conductive polysiloxane composition according to any one of [1] to [5] object.

According to the present invention, there is provided a thermally conductive polysiloxane composition that gives a cured product excellent in tackiness and flexibility.

[Definition of terms]
The structural unit of the siloxane compound may be described by the following abbreviations (hereinafter, these structural units may be referred to as “M unit”, “D unit”, etc., respectively).
M: —Si (CH ₃ ) ₃ O _1/2
^MH : -SiH (CH ₃ ) ₂ O _1/2
M ^Vi : —Si (CH═CH ₂ ) (CH ₃ ) ₂ O _1/2
D: Si (CH ₃ ) ₂ O _2/2
^DH : SiH (CH ₃ ) O _2/2
T: Si (CH ₃ ) O _3/2
Q: SiO _4/2 (tetrafunctional)

In the present specification, specific examples of groups are as follows.
Examples of the monovalent hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, and an alkenyl group. Examples of the monovalent hydrocarbon group having no aliphatic unsaturated bond include the monovalent hydrocarbon groups other than the alkenyl group.
Examples of the alkenyl group include a vinyl group, an allyl group, a 3-butenyl group, and a 5-hexenyl group.
Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, hexadecyl group and octadecyl group.
Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group.
Examples of the aryl group include a phenyl group, a naphthyl group, a tolyl group, and a xylyl group.
The alkenyl group, alkyl group, cycloalkyl group and aryl group may be substituted with a halogen such as chlorine, fluorine or bromine.

In this specification, “(A) thermally conductive filler” is also referred to as “(A)”. The same applies to “(E) platinum catalyst” and the like.

[Thermal conductive polysiloxane composition]
A thermally conductive polysiloxane composition (hereinafter also simply referred to as “composition”) includes (A) a thermally conductive filler, (B) a siloxane compound having an alkoxysilyl group and a linear siloxane structure, C) a polyorganosiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule, (D1) a linear polyorganohydrogensiloxane represented by the general formula (4), and (D2) a general formula (5) A polyorganohydrogensiloxane having at least three units shown in one molecule and (E) a platinum catalyst.
Since the cured product of the composition is excellent in tackiness, it is extremely suppressed that the cured product of the composition is peeled off from the base material, and at the same time, it becomes easy to reattach the cured product of the composition during repair. .

[(A) Thermally conductive filler]
(A) As a heat conductive filler, generally well-known inorganic filler is illustrated, Alumina, magnesium oxide, zinc oxide, boron nitride, aluminum nitride, silica powder, silicon carbide, metal powder, diamond, water Examples include aluminum oxide and carbon. Particularly preferred are alumina, zinc oxide, aluminum nitride or silicon carbide. These inorganic fillers are not particularly limited as long as they are grades that can be used as thermally conductive fillers, and commercially available ones can be used. Moreover, as an inorganic filler, it can also be used combining multiple types which are different chemical species.

The thermal conductive filler is not particularly limited as long as it has an available grade, but it is preferable to use a filler having an average particle size of 300 μm or less. Among those having an average particle size in this range, when a compound having a large average particle size is blended, the filling rate cannot be increased, whereas when the average particle size is small, the viscosity tends to increase. By appropriately selecting and blending the average particle size of the conductive filler, a composition having a viscosity suitable for the purpose can be obtained.

It is also preferable to use a filler having a relatively large particle size and a filler having a relatively small particle size in combination with the thermally conductive filler. By using a filler having a plurality of types of particle sizes in combination, a filler having a relatively small particle size enters the gap between the fillers having a relatively large particle size, thereby enabling higher filling. In the case where a plurality of types of fillers having different particle diameters are used, their blending ratio can be arbitrary.

The shape of the inorganic particles used for the heat conductive filler is not particularly limited. For example, any of spherical, round, and irregular shaped particles can be used, and at least two of them can be used in combination. The average particle size when the shape of the inorganic particles is round or irregular is defined by a method known to those skilled in the art. The average particle diameter can be obtained as a weight average value (or median diameter) or the like using, for example, a particle size distribution measuring apparatus such as a laser light diffraction method.

[(B) Siloxane compound having alkoxysilyl group and linear siloxane structure]
The composition contains a siloxane compound having an alkoxysilyl group and a linear siloxane structure as the surface treatment agent (A). The molecular structure of (B) is not particularly limited and is linear, branched or cyclic, but is preferably cyclic. As such preferable (B), general formula (1):

(Wherein R ¹ , R ² , R ³ , X, a, b, and c are as defined above). In the siloxane compound represented by the general formula (1), the unit containing R ¹ , the unit containing R ^2, and the unit represented by SiR ³ ₂ O must be arranged as shown in the general formula (1). For example, a unit represented by SiR ³ ₂ O may exist between a unit containing R ¹ and a unit containing R ² .

The siloxane compound represented by the general formula (1) can introduce a large number of hydrolyzable groups into the cyclic structure, and further, it is concentrated in position, so that the processing efficiency of the heat conductive filler is high. Therefore, it is considered that higher filling is possible. In addition, since the siloxane compound itself represented by the general formula (1) has high heat resistance, high heat resistance can be imparted to the composition.

In the general formula (1), R ¹ is a hydrolyzable functional group containing an alkoxysilyl group having 1 to 4 carbon atoms, and more specifically, a group having the following structure is exemplified. R ¹ may be directly bonded to X with silicon, but may be bonded to a linking group such as an ester bond. More specifically, examples of R ¹ include groups having the following structures.

Among these, R ¹ is preferably a group having a structure having two or more, particularly three, alkoxysilyl groups, from the viewpoint that the processing efficiency of the heat conductive filler tends to be further improved. From the viewpoint it is easy to obtain a raw material, R ¹ is preferably contains a methoxy silyl group.

R ² is a monovalent hydrocarbon group having 6 to 18 carbon atoms or the general formula (2):

(Wherein R ⁴ , Y and d are as defined above).

When R ² is a monovalent hydrocarbon group having 6 to 18 carbon atoms, an alkyl group having 6 to 18 carbon atoms is preferable, and an alkyl group having 6 to 14 carbon atoms is particularly preferable. R ² preferably has 6 or more carbon atoms in the longest carbon chain portion in the alkyl group, and in this case, it may have a branched structure as long as the total carbon number is within the above range. By making the number of carbons within this range, the effect on fluidity is enhanced and high blending is possible. Moreover, it is easy to handle and is easily dispersed uniformly.

When R ² is a linear triorganosiloxy group represented by the general formula (2), d is the 2-500 integer, preferably an integer from 4 to 400 and more preferably from 10 to 200 integer, more preferably 10 An integer of ˜100, particularly preferably an integer of 10 to 50. By setting it as this range, the effect with respect to fluidity | liquidity can be improved, high mixing | blending is enabled, and the viscosity of the siloxane compound shown by General formula (1) can be suppressed. R ⁴ is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms. In view of easy synthesis, R ⁴ is particularly preferably a methyl group. Y is a group selected from the group consisting of a methyl group, a vinyl group, and R ¹ . Since synthesis is easy, Y is preferably a methyl group or a vinyl group. R ² is a straight chain represented by the general formula (2) because there is a tendency to obtain an excellent handling property such as increasing the affinity by lowering the viscosity of the composition by mediating the heat conductive filler and the base polymer. It is preferably an organosiloxy group.

X is a linking group that binds R ¹ and R ² to the cyclic siloxane portion of the siloxane represented by the general formula (1). X is a divalent hydrocarbon group having 2 to 10 carbon atoms, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —, — An alkylene group having 2 to 10 carbon atoms such as CH ₂ CH (CH ₃ ) — and —CH ₂ CH (CH ₃ ) CH ₂ — is preferred. From the viewpoint of easy synthesis, X is particularly preferably —CH ₂ CH ₂ — or —CH ₂ CH (CH ₃ ) —.

R ³ is independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom. The monovalent hydrocarbon group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 6 carbon atoms. In view of easy synthesis, R ³ is particularly preferably a methyl group or a hydrogen atom.

A is an integer of 1 or more, preferably 1. b is an integer of 1 or more, and preferably 1 or 2. c is an integer of 0 or more, preferably 0-2. The sum of a + b + c is an integer of 4 or more, but is preferably 4 because synthesis is easy.

Therefore, the siloxane compound represented by the general formula (1) is preferably a compound represented by the following structural formula.

[(C) Polyorganosiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule]
(C) A polyorganosiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule is a base polymer. When the number of alkenyl groups bonded to the silicon atom is less than 2, the resulting composition is not sufficiently cured. Note that (C) does not have a hydrogen atom bonded to a silicon atom and an alkoxysilyl group. That is, (C) is not (B) and (D2).

Examples of the alkenyl group include alkenyl groups having 2 to 6 carbon atoms, and a vinyl group is preferable from the viewpoint of easy preparation. The alkenyl group may be bonded to either the end of the molecular chain or in the middle, but it is preferable to bond to both ends of the molecular chain from the viewpoint of obtaining a cured product having excellent flexibility. Examples of the group bonded to the silicon atom other than the alkenyl group include monovalent hydrocarbon groups having 1 to 12 carbon atoms that do not have an aliphatic unsaturated bond. As the hydrocarbon group having 1 to 12 carbon atoms having no aliphatic unsaturated bond, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms is preferable. A methyl group or a phenyl group is particularly preferred. (C) is linear or branched and is preferably linear.

Therefore, as (C), general formula (3):

A linear polyorganosiloxane represented by the formula (wherein R ⁵ , R ⁶ and e are as defined above) is more preferred.

In the general formula (3), R ⁶ has the same meaning as R ⁴ . In view of easy availability or preparation, R ⁵ is preferably a vinyl group and R ⁶ is preferably a methyl group. Accordingly, (C) is particularly preferably polymethylvinylsiloxane in which both ends are blocked with dimethylvinylsiloxane units and the intermediate unit is composed of dimethylsiloxane units.

The viscosity of (C) is 0.01 to 50 Pa · s at 23 ° C. from the viewpoint of excellent workability (viscosity and extrudability) as a composition, and a cured product excellent in flexibility. It is preferably 02 to 20 Pa · s, particularly preferably 0.05 to 10 Pa · s. It is preferable to adjust the weight average molecular weight of (C) so as to be in these viscosity ranges. The viscosity is a value measured under the condition of 23 ° C. using a B-type rotational viscometer. The rotor No. 1-No. 4 and the rotation speed includes 12, 30, and 60 rpm. The kind and rotation speed of a rotor can be suitably selected according to the viscosity of a measuring object.

[(D1) linear polyorganohydrogensiloxane]
(D1) The linear polyorganohydrogensiloxane has the general formula (4):

(Wherein R ⁷ , R ⁸ and f are as defined above). The hydrogen atom bonded to the silicon atom of (D1) and (D2) contributes as a crosslinking agent that performs a hydrosilyl reaction with the alkenyl group in (C).

In the general formula (4), the number of f is in the range of 1 to 200, preferably in the range of 5 to 100, more preferably in the range of 10 to 50. By setting it as this range, the effect on the fluidity is enhanced, high blending is possible, the viscosity of the siloxane compound itself can be suppressed, the shape stability is improved, and a cured product having superior flexibility is provided. R ⁸ is a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond, and is preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms. In view of easy synthesis, R ⁸ is particularly preferably a methyl group.

[(D2) Polyorganohydrogensiloxane having at least three units represented by general formula (5) in one molecule]
(D2) is represented by the general formula (5):
R ⁹ _g R ¹⁰ _h SiO _{({4- (g + h)} / 2)} (5)
(Wherein R ⁹ , R ¹⁰ , g and h are as defined above) have at least 3 units in one molecule. Note that (D2) does not have an alkoxysilyl group or an alkenyl group bonded to a silicon atom. That is, (D2) is not (B) and (C).

There is no restriction | limiting in particular in the molecular structure of (D2), It is linear, cyclic | annular, or branched. In the general formula (5), g is an integer of 0 to 2, preferably 1 or 2. h is an integer of 1 or 2, and is preferably 1. The sum of g + h is an integer of 1 to 3, but is preferably 3 because synthesis is easy. R ⁹ has the same meaning as ^{R 8.} From the viewpoint of easy availability or preparation, R ⁹ is preferably methyl. In the siloxane unit other than the unit represented by the general formula (5) in (D2), the organic group bonded to the silicon atom is independently the same as R ^9, and from the viewpoint of easy synthesis, methyl It is preferably a group. From the viewpoint of easy availability or synthesis, (D2) consists of R ¹¹ ₂ HSiO _1/2 units (wherein R ¹¹ is as defined above) and SiO _4/2 units, Further, polyorganohydrogensiloxane having 3 or more hydrogen atoms bonded to silicon atoms is preferable. The content of hydrogen atoms bonded to silicon in (D2) is not particularly limited, but is preferably 0.1 to 1.2% by weight, particularly preferably 0.5 to 1.1% by weight. . When the content of the hydrogen atom bonded to silicon of (D2) is 0.1% by weight or more, even when the content of (D2) is smaller, the thermal conductivity can be further increased. When the content is less than or equal to% by weight, the crosslink density does not become too high, and thereby a cured product having superior flexibility can be obtained. The molecular weight of (D2) is not particularly limited, but is preferably 330 to 50,000, particularly preferably 500 to 10,000. When the molecular weight of (D2) is 330 or more, the crosslinking density does not become too high, whereby a cured product that is superior in flexibility is obtained, and when it is 50,000 or less, the workability of the composition is excellent. In the present specification, the molecular weight is a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography. In the preferred (D2), the ratio of the R ¹¹ ₂ HSiO _1/2 unit and the SiO _4/2 unit can be appropriately adjusted so as to obtain the content and molecular weight of the hydrogen atom bonded to silicon.

[(E) Platinum catalyst]
(E) The platinum catalyst is a curing catalyst for obtaining a cured product by reacting the unsaturated group of (C) with the hydrogen atom bonded to silicon of (D). Examples of the platinum catalyst include chloroplatinic acid, platinum olefin complex, platinum vinylsiloxane complex, platinum phosphorus complex, platinum alcohol complex, platinum black and the like. Further, in order to obtain a longer pot life, the activity of the catalyst can be suppressed by adding (F) a reaction inhibitor. Known reaction inhibitors for platinum catalysts include acetylene alcohols such as 2-methyl-3-butyn-2-ol and 1-ethynyl-2-cyclohexanol, and diallyl maleate.

[composition]
The content of each component in the composition is as follows.
The content of (A) is preferably 10 to 5,000 parts by mass, and 50 to 4,000 parts by mass with respect to 100 parts by mass in total of (B), (C), (D1) and (D2). Part is more preferable, and 100 to 3,000 parts by mass is particularly preferable. By setting it as such a range, thermal conductivity increases more.

The content of (B) is preferably 0.01 to 20 parts by mass, particularly preferably 0.1 to 15 parts by mass with respect to 100 parts by mass of (A). By making the quantity of (B) into this range, heat conductivity can be made higher, improving the filling property of a heat conductive filler.
Further, the content of (B) is preferably 0.01 parts by mass or more, and 0.1 to 500 parts by mass with respect to 100 parts by mass of (C), (D1) and (D2). Is particularly preferred. When the amount of (B) is 0.01 parts by mass or more with respect to 100 parts by mass of (C), (D1) and (D2), the surface treatment effect of the thermally conductive filler is sufficiently exerted ( A) can be blended higher. When the amount of (B) is 500 parts by mass or less with respect to 100 parts by mass of (C), (D1), and (D2), the mechanical properties and / or heat resistance after curing is improved.

The content of (C) can be appropriately set according to the thermal conductivity required for the composition, but (A) is preferably 1 to 30 parts by mass with respect to 100 parts by mass, and 3 to 20 parts by mass. More preferably, it is a part.

The content of (E) is preferably 0.1 to 1,000 ppm as platinum element with respect to the alkenyl group-containing polyorganosiloxane of (C). In such a range, the curability and the curing speed are sufficient.

The contents of (C), (D1) and (D2) can be appropriately set according to the thermal conductivity required for the composition, but the silicon of (D1) relative to the number of alkenyl groups Vi _C of (C) the ratio of the sum in which the number of bound to atoms and the number _{H D1} hydrogen atoms to the number _{H D2} of the hydrogen atoms bonded to silicon atoms _{_{(D2) (H D1 + H}} D2) ((H D1 + H D2) / Vi C ) Is preferably less than 1.50. When _{_{(H D1 + H D2) /}} Vi C is less than 1.50, the elongation of the cured product becomes higher, also tackiness more excellent. (H _D1 + H _D2 ) / Vi _C is preferably 1.20 or less, more preferably 1.10 or less, still more preferably 0.90 or less, and 0.80 or less. Is particularly preferred. (H _D1 + H _D2 ) / Vi _C is not particularly limited, but is preferably 0.60 or more, more preferably 0.70 or more, and particularly preferably 0.80 or more.

The ratio (H _D1 : H _D2 ) of the number H _{D1 of} hydrogen atoms bonded to the silicon atom (D1) to the number H _{D2 of} hydrogen atoms bonded to the silicon atom ( _D2 ) is not particularly limited. It is preferably 9: 0.1 to 1: 9, and more preferably 9: 1 to 5: 5. Within such a range, the elongation of the cured product of the composition becomes higher and the tackiness is better.

It is particularly preferable that (H _D1 + H _D2 ) / Vi _C is 0.85 or less, and H _D1 : H _D2 is 9: 1 to 8: 2. Within such a range, the elongation of the cured product of the composition is particularly high, and the tackiness is particularly excellent.

As a method for preparing the composition, (B), (C), (D1) and (D2), and (A) may be prepared as they are using a kneading apparatus, or (B) After (A) is first mixed and surface-treated, it may be dispersed and prepared in (C), (D1) and (D2). Moreover, you may implement the process by a heating, pressure reduction, or another well-known method as needed. Moreover, the mixture which mix | blended (C) previously can be prepared, and the mixture of (D1), (D2), and (E) can also be added immediately before making it harden | cure. (F) is preferably added at the same stage as (E).

In the composition, a pigment, a flame retardant, an adhesion-imparting agent, a heat-imparting agent, a diluent, an organic solvent and the like known to those skilled in the art may be appropriately blended as necessary, as long as the effects of the present invention are not impaired. it can. Since the cured product of the composition has high elongation, it has excellent followability to deformation (for example, bending) of the base material when an adhesion-imparting agent is added as an optional component.

The composition can be cured at room temperature or by applying heat. Conditions for thermosetting are known to those skilled in the art, but examples of equipment that can be used for the curing reaction by heat include apparatuses known to those skilled in the art such as a thermostatic bath. The heating conditions can be appropriately adjusted according to the heat resistant temperature of the member to which the composition is applied, and the curing time can be determined. For example, heat of room temperature (23 ° C.) to 120 ° C. or less can be applied in the range of 1 minute to 5 hours. The heating temperature is preferably 40 to 120 ° C., more preferably 50 to 110 ° C., and particularly preferably 60 to 100 ° C. from the viewpoint of operability. The heating time is preferably 5 minutes to 72 hours, more preferably 5 minutes to 3 hours, and particularly preferably 10 minutes to 2 hours, from the viewpoint of simplicity of the curing step. Moreover, when making it harden | cure at room temperature, it is preferable that hardening time is 72 hours or less, and 24 hours or less are especially preferable.

Silicone rubber obtained by curing the composition can be used as a heat radiating member for electronic parts such as electronic devices and integrated circuit elements.

Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following examples and comparative examples, all parts represent parts by mass.

[Examples 1 to 15, Comparative Examples 1 to 3]
The materials used in Examples and Comparative Examples are as follows.
<(A) Thermally conductive filler>
AS-40: Round alumina with an average particle size of 12 μm (manufactured by Showa Denko KK)
AL43KT: Polygonal alumina having an average particle size of 4.6 μm (manufactured by Showa Denko KK)
AL160SG-4: Easily sinterable alumina with an average particle size of 0.55 μm (manufactured by Showa Denko KK)
Silazane-treated silica: silica obtained by treating fumed silica (AEROSIL 200: manufactured by Nippon Aerosil Co., Ltd.) with an average particle size of 200 μm with hexamethyldisilazane

<(B) Siloxane compound having alkoxysilyl group and linear siloxane structure>
(B1) Cyclic siloxane compound having a polysiloxane chain with a polymerization degree of 70 (compound 1):

In a 5,000 mL flask, 1,100 g of 3- (methacryloyloxy) propyltrimethoxysilane was added to a solution of 440 g of toluene and 1,992 g of cyclic siloxane having three Si—H bonds in the presence of a platinum catalyst. Reaction was performed at 120 degreeC for 3 hours. The solvent was removed from the resulting reaction solution, followed by distillation to obtain a colorless liquid.
1,650 g of linear vinyl polysiloxane (polysiloxane represented by MD ₇₀ M ^Vi : manufactured by Momentive) was added to 77 g of the obtained liquid. Further, a platinum catalyst was added, and the reaction was carried out at 120 ° C. for 5 hours to obtain the target siloxane as a colorless oil having a viscosity of 0.20 Pa · s.
The FT IR measurement, the disappearance of the absorption peak derived from Si-H groups in the vicinity 2,150Cm ^-1, confirmed the absorption peak derived from a methoxy group near 2,850cm ^-1. ^{In 1} H NMR measurement (500 MHz, in CDCl ₃ ), a signal derived from a methoxy group was observed at 3.56 ppm, and the number of D units was determined from an integration ratio with a signal derived from a methyl group adjacent to silicon near 0.04 ppm. It was confirmed that two linear polysiloxane structures of approximately 70 were introduced per molecule. As a result of GPC measurement, a monodisperse peak (dispersion degree 1.15) was confirmed, and the measured average molecular weight was in good agreement with the structural formula.

(B2) Cyclic siloxane compound having a polysiloxane chain with a polymerization degree of 30 (compound 2):

In a 5,000 mL flask, 1,100 g of vinyltrimethoxysilane was added to a solution of 440 g of toluene and 1,992 g of cyclic siloxane having two Si—H bonds in the presence of a platinum catalyst. Reaction was performed at 120 degreeC for 3 hours. The solvent was removed from the resulting reaction solution, followed by distillation to obtain a colorless liquid. To 77 g of the obtained liquid, 450 g of linear vinyl polysiloxane (polysiloxane represented by MD ₃₀ M ^Vi : manufactured by Momentive) was added. Further, a platinum catalyst was added, and the reaction was carried out at 120 ° C. for 5 hours to obtain the desired siloxane as a colorless oil.
By FT IR measurement, an absorption peak derived from a methoxy group was confirmed in the vicinity of 2,850 cm ⁻¹ . ^{In 1} H NMR measurement (500 MHz, in CDCl ₃ ), a signal derived from a methoxy group was observed at 3.56 ppm, and the number of D units was found from an integration ratio with a signal derived from a methyl group adjacent to silicon near 0.04 ppm. It was confirmed that one linear polysiloxane structure of about 30 was introduced per molecule. As a result of GPC measurement, a monodisperse peak (dispersion degree 1.15) was confirmed, and the measured average molecular weight was in good agreement with the structural formula.

<(C) Polyorganosiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule>
(C1) M ^Vi D _n M ^Vi 0.5 Pa · s: α, ω-divinylpolydimethylsiloxane; viscosity 0.5 Pa · s
(C2) M ^Vi D _n M ^Vi 0.1 Pa · s: α, ω-divinylpolydimethylsiloxane; viscosity 0.1 Pa · s
(C3) M ^Vi D _n M ^Vi 1.0 Pa · s: α, ω-divinylpolydimethylsiloxane; viscosity 1.0 Pa · s
<(D1) Polyorganohydrogensiloxane>
^MH D ₂₀ ^MH 0.02 Pa · s: Viscosity 0.02 Pa · s
<(D2) Polyorganohydrogensiloxane>
M ^H _m Q 0.02Pa · s: consists polymethyl hydrogen siloxane ^{(M H} and Q units represented by the aforementioned average structural formula ^M _{H m} Q, 3 pieces in one molecule, the hydrogen atoms bonded to silicon atoms Polymethylhydrogensiloxane) (content of hydrogen atom bonded to silicon: 1.0% by weight, number average molecular weight in terms of polystyrene: 800): viscosity 0.02 Pa · s
<Other (D)>
MD ₂₀ ^DH ₂₀ M
<(E) Platinum catalyst>
Pt-M ^Vi M ^Vi : 1,2-divinyltetramethyldisiloxane complex of platinum <(F) reaction inhibitor>
Surfynol 61 (manufactured by Nissin Chemical Industry Co., Ltd.)

[Preparation of Thermally Conductive Polysiloxane Composition]
(A), (B), and (C) were kneaded by a predetermined method using a planetary mixer with the blending amounts (parts by mass) shown in Tables 1 to 3 to obtain a mixture. Thereafter, (D1), (D2), (E) and (F) were added and kneaded by a predetermined method using a planetary mixer to obtain a composition. In Comparative Example 1, (D2) was not added, in Comparative Example 2, (D1) was not added, and in Comparative Example 3, other (D) was added instead of (D2).

[Characteristic]
The following characteristics were measured for the composition and the cured product of the composition.
(1) Viscosity The viscosity of the composition is determined according to JIS K6249 using a B-type rotational viscometer (Bismetron VDH) (manufactured by Shibaura System Co., Ltd.). Using 7 rotors, measurement was performed at 10 rpm for 1 minute under the conditions at 23 ° C.
(2) Hardness The composition was filled in a 6 mm-thick mold and cured by heating at 70 ° C. for 30 minutes. The hardness (Type E hardness) of the cured product of the composition was measured according to JIS K6249.
(3) Elongation The composition was filled in a 2 mm thick mold and cured by heating at 70 ° C. for 30 minutes. Using the obtained heat conductive silicone rubber sheet having a thickness of 2 mm, the elongation of the cured product of the composition B was measured according to JIS K6249.
(4) Thermal conductivity The thermal conductivity of the composition was a Teflon (registered trademark) coated aluminum mold with an inner diameter of 30 mm and a depth of 6 mm using a thermal conductivity meter (TPS 1500, manufactured by Kyoto Electronics Industry Co., Ltd.). The container is filled with the composition, cured by heating at 70 ° C. for 30 minutes, and a thermal conductivity meter sensor is sandwiched between the two prepared samples, and the thermal conductivity of the cured product (unit: W / ( m · K)) was measured.
(5) Probe tack test 60 mm × 30 mm 6 mm deep Teflon (registered trademark) coated aluminum mold container filled with the composition and cured by heating at 70 ° C. for 30 minutes. The tackiness was measured according to JIS Z0237.

The results are shown in Tables 1 to 3. The amount of platinum catalyst in the table is a platinum element equivalent amount.

The cured products of the compositions of the examples were all excellent in flexibility and tackiness because of their high elongation.
Comparative Example 1, 3, 7 and 8, as well as by comparison of Examples 6 and _2, the value of _{H D1} to the sum of _{H D1} and _{H D2} increases, the elongation is higher, better by tackiness It was.
Comparative Example Comparison of 2-5, Comparative Examples 6 and 7, Examples 10-12, and by comparison of Examples _13-15, becomes smaller _{(H D1 + H D2) /} Vi C, elongation Became higher.
In comparison between Examples 2 to 5, Examples 2 and 3 in which (H _D1 + H _D2 ) / Vi _C was 0.85 or less were particularly excellent in tackiness.
According to the comparison of Examples 9 and 11, when the viscosity of (C) was increased, the elongation was higher and the tackiness was better.
On the other hand, since the comparative example 1 is a composition which does not contain (D2), the composition did not harden | cure. Since Comparative Example 2 was a composition not containing (D1), the elongation of the cured product of the composition was extremely insufficient and the tackiness was poor. In Comparative Example 3, a crosslinking agent having a hydrogen atom bonded to silicon as an intermediate unit is used instead of (D2), but the elongation of the cured product of the composition is insufficient and the tackiness is improved. It was inferior.

Claims

(A) a thermally conductive filler;
(B) a siloxane compound having an alkoxysilyl group and a linear siloxane structure;
(C) a polyorganosiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule;
(D1) General formula (4):

(Where
R 7 is a hydrogen atom,
R 8 is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond;
f is 1 to 200)
A linear polyorganohydrogensiloxane represented by:
(D2) General formula (5):
R 9 g R 10 h SiO ({4- (g + h)} / 2) (5)
(Where
R 9 independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond;
R 10 is a hydrogen atom,
g is an integer from 0 to 2,
h is an integer of 1 or 2,
g + h is an integer of 1 to 3,
(Except when g is 1 and h is 1)
A polyorganohydrogensiloxane having at least three units represented by
(E) A thermally conductive polysiloxane composition comprising a platinum catalyst.
(C) The number of hydrogen atoms bonded to the silicon atom of (D1) H D1 and the number of hydrogen atoms bonded to the silicon atom of (D2) H D2 with respect to the number Vi C of alkenyl groups (C) the ratio of H D1 + H D2) (( H D1 + H D2) / Vi C) is less than 1.50, the thermally conductive polysiloxane composition of claim 1.
(D2) is composed of R 11 2 HSiO 1/2 unit (wherein R 11 has the same meaning as R 9 ) and SiO 4/2 unit, and a hydrogen atom bonded to a silicon atom is contained in one molecule. The thermally conductive polysiloxane composition according to claim 1, which is a polyorganohydrogensiloxane having 3 or more.
The ratio between the number H D1 of hydrogen atoms bonded to silicon atoms to the number H D2 of hydrogen atoms bonded to silicon atoms (D2) of (D1) (H D1: H D2) is 9.9: 0.1 to The thermally conductive polysiloxane composition according to any one of claims 1 to 3, wherein the composition is 1: 9.
(B) is represented by the general formula (1):

(Where
R 1 is a group having an alkoxysilyl group having 1 to 4 carbon atoms,
R 2 is a monovalent hydrocarbon group having 6 to 18 carbon atoms or the general formula (2):

(Where
R 4 is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms,
Y is a group selected from the group consisting of a methyl group, a vinyl group, and R 1 ;
d is an integer of 2 to 500)
A linear organosiloxy group represented by
X is independently a divalent hydrocarbon group having 2 to 10 carbon atoms,
a and b are each independently an integer of 1 or more;
c is an integer of 0 or more,
a + b + c is an integer of 4 or more,
R 3 is independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom)
The thermally conductive polysiloxane composition according to any one of claims 1 to 4, which is a siloxane compound represented by the formula:
(C) is represented by the general formula (3):

(Where
R 5 is independently an alkenyl group having 2 to 6 carbon atoms,
R 6 is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms,
e is a linear polyorganosiloxane having a viscosity of 0.01 to 50 Pa · s at 23 ° C.). Siloxane composition.