JP6217588B2 - Thermally conductive silicone potting composition - Google Patents

Description

  The present invention relates to a thermally conductive silicone potting composition that efficiently transfers heat of a heat-generating component.

  In the automobile industry, the power electronics industry, and the like, the use of electrical equipment is rapidly progressing from the viewpoint of improving convenience, safety, and energy saving, and the number of heat generating components required is also increasing rapidly.

  Among such heat-generating electronic components, a structure is known in which a thermally conductive silicone rubber composition is brought into close contact between a heat-generating component and a cooler so as to be thermally connected to protect electronic components that are vulnerable to heat. Japanese Patent No. 3543663 (Patent Document 1) proposes a material suitable for the application. However, in such a structure, when it becomes a component having a fine structure, it becomes difficult to closely contact the entire heat generating portion and the heat conductive silicone rubber, and heat cannot be efficiently released.

  Therefore, if a heat-generating silicone potting composition with high fluidity is poured into the case and a highly heat-conductive silicone potting composition is poured into the case, the heat-conductive silicone potting composition spreads to every corner of the heat-generating parts. Thus, since the heat generating component and the cooler (case) can be thermally connected, heat can be efficiently released. And the heat conductive silicone potting composition corresponding to such a use is proposed by patent 5304623 (patent document 2).

  However, in recent years, as performance of heat-generating parts, space saving, and weight reduction are required, not only the amount of heat generated from heat-generating parts is increased, but also the heat density is increased, and the heat conductive silicone potting composition There is a need for further improvements in thermal conductivity. In order to further improve the thermal conductivity of the thermally conductive silicone potting composition, it is necessary to add a large amount of thermally conductive filler, and as a result, the fluidity of the thermally conductive silicone potting composition is lost. The problem arises. For this reason, conventionally, in the case of a thermally conductive silicone potting composition, when practical fluidity is maintained, a thermal conductivity of about 1.0 W / m · K has been the limit.

  As one of means for realizing such high thermal conductivity, a thermally conductive silicone composition using an organopolysiloxane whose one end is blocked with an alkoxysilyl group is disclosed in Japanese Patent No. 4664696 (Patent Document 3). Proposed. However, even when this composition is used, when a thermally conductive filler is added until a high thermal conductivity of about 2.0 to 4.0 W / m · K, fluidity does not develop, and this composition is It was difficult to fill every corner of a case in which fine parts were incorporated. Also, as the heat conductive filler increases, the hardness after curing tends to increase. However, for fine parts, there is a risk of causing damage to other parts that come into contact with them. Is preferably low hardness. However, it has been difficult to achieve low hardness with this composition.

  Thus, there is a strong demand for a thermally conductive silicone potting composition that can achieve both high thermal conductivity and fluidity due to a large amount of thermally conductive filler, and further has low hardness after curing. Yes.

Japanese Patent No. 3543663 Japanese Patent No. 5304623 Japanese Patent No. 4664696

  The present invention has been made in view of the above circumstances, and has a high fluidity and can flow into a fine space in spite of containing a large amount of a heat conductive filler, and gives a low hardness cured product. An object is to provide a conductive silicone potting composition.

  As a result of intensive studies to achieve the above object, the present inventor, as a result of addition reaction curing type heat conductive silicone composition containing a large amount of heat conductive filler, in particular, both ends are blocked with alkoxysilyl groups. By combining the organopolysiloxane component and the organopolysiloxane component whose one end is blocked with an alkoxysilyl group, etc., both high thermal conductivity and high fluidity can be achieved. It has been found that by adding a linear organohydrogensiloxane component having a Si-H group at the terminal, a thermally conductive silicone potting composition that provides a cured product with low hardness while having high adhesion can be provided. The present invention has been made.

（式（１）中、Ｒ¹は独立に非置換又は置換の１価炭化水素基であり、Ｒ²は独立にアルキル基、アルコキシアルキル基、アルケニル基、又はアシル基である。ｎは２〜１００の整数であり、ａは１〜３の整数である。）
で示されるオルガノポリシロキサン： １〜２００質量部、
（Ｄ）下記一般式（２）

（式（２）中、Ｒ³は独立に炭素数１〜６のアルキル基であり、Ｒ⁴は独立に水素原子、それぞれ炭素原子若しくは炭素原子と酸素原子を介して珪素原子に結合しているエポキシ基、アクリロイル基、メタクリロイル基又はトリアルコキシシリル基、又はオキシアルキル基、アルキルオキシアルキル基、パーフルオロオキシアルキル基、パーフルオロアルキルオキシアルキル基若しくはフェニル含有１価有機基であるが、Ｒ⁴で示される基のうち３以上は水素原子である。ｐは２〜１０の正の整数である。）
で示されるオルガノハイドロジェンポリシロキサン、
（Ｅ）下記一般式（３）

（式（３）中、Ｒ⁵は独立に炭素数１〜６のアルキル基であり、ｑは５〜１，０００の正の整数である。）
で示されるオルガノハイドロジェンポリシロキサン、
（Ｆ）熱伝導性充填材： ４００〜３，０００質量部、及び
（Ｇ）白金族金属系触媒： 触媒量
を含有し、
上記（Ｄ）成分及び（Ｅ）成分の配合量が、
［（Ｄ）成分と（Ｅ）成分のＳｉ−Ｈ基の合計個数］／［（Ａ）成分のアルケニル基と、（Ｂ）成分、（Ｃ）成分がアルケニル基を含む場合はそれらのアルケニル基も含めたアルケニル基の合計個数］が０．６〜１．５の範囲にあり、［（Ｄ）成分のＳｉ−Ｈ基の個数］／［（Ｅ）成分のＳｉ−Ｈ基の個数］が１〜１０の範囲にあることを特徴とする熱伝導性シリコーンポッティング組成物。
〔２〕更に、（Ｈ）反応制御剤を、（Ａ）成分１００質量部に対して、０．０１〜５．０質量部含有する〔１〕に記載の熱伝導性シリコーンポッティング組成物。
〔３〕チキソトロピックインデックスが１．３以下である〔１〕又は〔２〕に記載の熱伝導性シリコーンポッティング組成物。
〔４〕ＪＩＳ Ｋ ６２５３に規定のタイプＡデュロメーターにて６０以下である硬化物を与える〔１〕〜〔３〕のいずれかに記載の熱伝導性シリコーンポッティング組成物。 Accordingly, the present invention provides the following thermally conductive silicone potting composition.
[1] (A) Organopolysiloxane having a viscosity of 0.01 to 100 Pa · s at 25 ° C. and having an alkenyl group bonded to at least two silicon atoms in one molecule: 100 parts by mass
(B) Organopolysiloxane having a viscosity of 0.01 to 100 Pa · s at 25 ° C. and having both ends blocked with trialkoxysilyl groups: 1 to 200 parts by mass,
(C) The following general formula (1)

(In formula (1), R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. (It is an integer of 100, and a is an integer of 1 to 3.)
An organopolysiloxane represented by: 1 to 200 parts by mass,
(D) The following general formula (2)

(In formula (2), R ³ is independently an alkyl group having 1 to 6 carbon atoms, and R ⁴ is independently bonded to a silicon atom via a hydrogen atom, or a carbon atom or a carbon atom and an oxygen atom, respectively. epoxy group, an acryloyl group, a methacryloyl group or trialkoxysilyl group, or an oxyalkyl group, alkyloxyalkyl group, perfluorooxyalkyl group, is a perfluoroalkyloxy group or a phenyl-containing monovalent organic group, with R ⁴ 3 or more of the groups shown are hydrogen atoms, and p is a positive integer of 2 to 10.)
An organohydrogenpolysiloxane represented by
(E) The following general formula (3)

(In formula (3), R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and q is a positive integer of 5 to 1,000.)
An organohydrogenpolysiloxane represented by
(F) Thermally conductive filler: 400 to 3,000 parts by mass, and (G) platinum group metal catalyst: containing a catalytic amount,
The blending amount of the component (D) and the component (E)
[Total number of Si-H groups in component (D) and component (E)] / [Alkenyl group in component (A) and (B) component and component (C) if they contain alkenyl groups, these alkenyl groups The total number of alkenyl groups, including the number of Si—H groups in component (D)] / [the number of Si—H groups in component (E)]. A heat conductive silicone potting composition characterized by being in the range of 1-10.
[2] The thermally conductive silicone potting composition according to [1], further comprising (H) a reaction control agent in an amount of 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the component (A).
[3] The thermally conductive silicone potting composition according to [1] or [2], wherein the thixotropic index is 1.3 or less.
[4] The thermally conductive silicone potting composition according to any one of [1] to [3], which gives a cured product having a value of 60 or less according to JIS K 6253 using a specified type A durometer.

  According to the thermally conductive silicone potting composition of the present invention, despite having a large amount of thermally conductive filler, it has high fluidity and can flow into a fine space, and has high thermal conductivity after curing. And low hardness. For this reason, for example, it is effective for potting a case that acts as a cooling member containing fine heat-generating components, and heat from these fine heat-generating components is efficiently transferred to the case, and stress is not easily applied to the fine heat-generating components. It can be provided as a thermally conductive silicone potting composition.

Hereinafter, the present invention will be described in more detail.
[Thermal conductive silicone potting composition]
The thermally conductive silicone potting composition of the present invention cures at room temperature or under heat and adheres to a metal, an organic resin or the like. (A) Organopoly having at least two alkenyl groups in one molecule (B) organopolysiloxane blocked at both ends with trialkoxysilyl groups, (C) organopolysiloxane blocked at one end with alkoxysilyl groups, (D) cyclic organohydrogenpolysiloxane, (E ) It contains a linear organohydrogensiloxane having Si-H groups at both ends, (F) a thermally conductive filler, (G) a platinum group metal catalyst, and (H) a reaction control agent if necessary. is there.

[Component (A)]
The component (A) has a viscosity at 25 ° C. of 0.01 to 100 Pa · s, preferably 0.03 to 10 Pa · s, and has an alkenyl group bonded to at least two silicon atoms in one molecule. Siloxane. When the viscosity at 25 ° C. is less than 0.01 Pa · s, the storage stability of the composition deteriorates, and when it exceeds 100 Pa · s, the fluidity of the composition deteriorates. The viscosity here is a value measured by a rotational viscometer (hereinafter the same).

  Such an organopolysiloxane is not particularly limited as long as it satisfies the above viscosity and alkenyl group content, and a known organopolysiloxane can be used, and the structure thereof may be linear or branched, and is different. It may be a mixture of two or more organopolysiloxanes having a viscosity.

  The alkenyl group bonded to the silicon atom has 2 to 10 carbon atoms, preferably 2 to 8 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 1-butenyl group, and a 1-hexenyl group. Among these, a vinyl group is preferable from the viewpoint of ease of synthesis and cost. The alkenyl group may be present at either the terminal or the middle of the molecular chain of the organopolysiloxane, but in terms of flexibility, it is preferably present only at both terminals.

  Examples of the organic group other than the alkenyl group bonded to the silicon atom include monovalent hydrocarbon groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. Examples of such a monovalent hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a dodecyl group, an aryl group such as a phenyl group, a 2-phenylethyl group, 2- Aralkyl groups such as phenylpropyl groups, and fluorocarbon groups, bromoethyl groups, chloromethyl groups, 3,3,3-, in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with halogen atoms such as chlorine, fluorine, bromine, etc. And halogen-substituted monovalent hydrocarbon groups such as a trifluoropropyl group. Especially, it is preferable that 90 mol% or more is a methyl group from the surface of the ease of synthesis | combination and cost.

  From the above, the component (A) is particularly preferably dimethylpolysiloxane in which both ends are blocked with dimethylvinylsilyl groups.

[(B) component]
The component (B) has a viscosity at 25 ° C. of 0.01 to 100 Pa · s, preferably 0.03 to 10 Pa · s, more preferably 0.05 to 5 Pa · s, and both ends are trialkoxysilyl groups. It is a sequestered organopolysiloxane and has the role of lowering the viscosity of the composition and imparting fluidity. When the viscosity at 25 ° C. is less than 0.01 Pa · s, it causes oil bleeding, and when it exceeds 100 Pa · s, the composition becomes highly viscous and fluidity deteriorates. In addition, each alkoxy group constituting the trialkoxysilyl group at both ends is preferably independently having 1 to 6 carbon atoms, particularly 1 to 4 carbon atoms, and examples thereof include a trimethoxysilyl group and a triethoxysilyl group.

  In such an organopolysiloxane, other than the structure at both ends is not particularly limited, and examples of the substituent bonded to silicon atoms other than both ends include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. A monovalent hydrocarbon group having 1 to 8 carbon atoms such as an alkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group or a tolyl group, or the like. Examples thereof include halogenated hydrocarbon groups such as chloromethyl groups and trifluoromethyl groups in which some or all of the hydrogen atoms of the hydrocarbon groups are substituted with halogen atoms such as chlorine atoms, fluorine atoms, bromine atoms and the like.

式（４）中、Ｒ⁶は互いに同一又は異種の炭素数１〜４のアルキル基であり、具体的には、メチル基、エチル基、プロピル基、ブチル基が挙げられ、特にメチル基、エチル基が好ましい。Ｒ⁷は互いに同一又は異種の炭素数１〜８の非置換又は置換の１価炭化水素基であり、具体的には、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基等のアルキル基、フェニル基、トリル基等のアリール基などの１価炭化水素基、これら１価炭化水素基の水素原子の一部又は全部を塩素原子、フッ素原子、臭素原子等のハロゲン原子で置換したクロロメチル基、３−クロロプロピル基、トリフルオロメチル基等のハロゲン化炭化水素基が挙げられ、特にメチル基、エチル基が好ましい。また、ｒは式（４）で示されるオルガノポリシロキサンの２５℃における粘度を０．０１〜１００Ｐａ・ｓとするような数である。 The component (B) can be preferably represented by the following formula (4).

In the formula (4), R ⁶ is the same or different alkyl group having 1 to 4 carbon atoms, and specific examples include a methyl group, an ethyl group, a propyl group, and a butyl group. Groups are preferred. R ⁷ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms that is the same or different from each other, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, Alkyl groups such as heptyl groups, monovalent hydrocarbon groups such as aryl groups such as phenyl and tolyl groups, and some or all of the hydrogen atoms of these monovalent hydrocarbon groups are halogens such as chlorine, fluorine and bromine atoms. Halogenated hydrocarbon groups such as a chloromethyl group, a 3-chloropropyl group, and a trifluoromethyl group substituted with an atom are exemplified, and a methyl group and an ethyl group are particularly preferable. Moreover, r is a number which makes the viscosity at 25 degreeC of the organopolysiloxane shown by Formula (4) 0.01-100 Pa.s.

  (B) The compounding quantity of a component is 1-200 mass parts with respect to 100 mass parts of (A) component, Preferably it is 5-180 mass parts, More preferably, it is 10-170 mass parts. When it is less than 1 part by mass, fluidity can be imparted, and when it exceeds 200 parts by mass, the composition has a high viscosity.

（式（１）中、Ｒ¹は独立に非置換又は置換の１価炭化水素基であり、Ｒ²は独立にアルキル基、アルコキシアルキル基、アルケニル基、又はアシル基である。ｎは２〜１００の整数であり、ａは１〜３の整数である。）
で示されるオルガノポリシロキサンであり、組成物の粘度を下げ、流動性を付与する役割を有する。 [Component (C)]
Component (C) is represented by the following general formula (1)

(In formula (1), R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. (It is an integer of 100, and a is an integer of 1 to 3.)
It has the role which lowers | hangs the viscosity of a composition and provides fluidity | liquidity.

In the formula (1), R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, such as a linear alkyl group. A branched alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group, an aralkyl group, a halogenated alkyl group, and a cyanoalkyl group. Examples of the linear alkyl group include a methyl group, an ethyl group, a propyl group, a hexyl group, and an octyl group. Examples of the branched alkyl group include isopropyl group, isobutyl group, tert-butyl group, and 2-ethylhexyl group. Examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkenyl group include a vinyl group and an allyl group. Examples of the aryl group include a phenyl group and a tolyl group. Examples of the aralkyl group include 2-phenylethyl group and 2-methyl-2-phenylethyl group. Examples of the halogenated alkyl group include 3,3,3-trifluoropropyl group, 2- (nonafluorobutyl) ethyl group, and 2- (heptadecafluorooctyl) ethyl group. Examples of the cyanoalkyl group include a cyanoethyl group. Among them, R ¹ is preferably a methyl group, a phenyl group, or a vinyl group.

In formula (1), R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. Examples of the alkyl group include a linear alkyl group, a branched alkyl group, and a cyclic alkyl group as in the case of R ¹ . Examples of the alkoxyalkyl group include a methoxyethyl group and a methoxypropyl group. Examples of the acyl group include an acetyl group and an octanoyl group. Among these, as R ² , an alkyl group is preferable, and a methyl group and an ethyl group are particularly preferable.

  In Formula (1), n is an integer of 2-100, Preferably it is 5-80. A is an integer of 1 to 3, preferably 3.

  The viscosity of component (C) at 25 ° C. is usually 0.005 to 10 Pa · s, particularly preferably 0.005 to 1 Pa · s. When the viscosity at 25 ° C. is less than 0.005 Pa · s, oil bleed is likely to occur from the composition, and the adhesive force may decrease with time. When the viscosity exceeds 10 Pa · s, There exists a possibility that the viscosity of a composition may become high and fluidity | liquidity may become scarce.

The following organopolysiloxane is mentioned as a suitable specific example of (C) component.

  Such (C) component may be used individually by 1 type, or may use 2 or more types together.

  (C) The compounding quantity of a component is 1-200 mass parts with respect to 100 mass parts of (A) component, Preferably it is 10-180 mass parts. When the amount is less than 1 part by mass, a low-viscosity composition cannot be obtained, and when it exceeds 200 parts by mass, the composition is difficult to cure.

（式（２）中、Ｒ³は独立に炭素数１〜６のアルキル基であり、Ｒ⁴は独立に水素原子、それぞれ炭素原子若しくは炭素原子と酸素原子を介して珪素原子に結合しているエポキシ基、アクリロイル基、メタクリロイル基又はトリアルコキシシリル基、又はエーテル含有１価有機基若しくはフェニル含有１価有機基であるが、Ｒ⁴で示される基のうち３以上は水素原子である。ｐは２〜１０の正の整数である。）
で示されるオルガノハイドロジェンポリシロキサンであり、高接着性を有しつつ、組成物の硬化後に低硬度を発現させる役割を有する。 [Component (D)]
Component (D) is represented by the following general formula (2)

(In formula (2), R ³ is independently an alkyl group having 1 to 6 carbon atoms, and R ⁴ is independently bonded to a silicon atom via a hydrogen atom, or a carbon atom or a carbon atom and an oxygen atom, respectively. An epoxy group, an acryloyl group, a methacryloyl group or a trialkoxysilyl group, or an ether-containing monovalent organic group or a phenyl-containing monovalent organic group, but three or more of the groups represented by R ⁴ are hydrogen atoms. (It is a positive integer from 2 to 10.)
The organohydrogenpolysiloxane represented by the formula (1) has a role of developing low hardness after curing of the composition while having high adhesiveness.

In formula (2), R ³ is independently an alkyl group having 1 to 6 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Of these, 90% or more is preferably a methyl group from the viewpoint of ease of synthesis and cost.

In the formula (2), when 3 or more of the groups represented by R ⁴ are not hydrogen atoms, the component (B) cannot react with an alkenyl group such as the component (A) to form a crosslinked structure.

Of the groups represented by R ⁴ in the formula (2), examples of the group other than a hydrogen atom include a 3-glycidoxypropyl group, a 3-glycidoxypropylmethyl group, a 3-glycidoxyethyl group, 3 Epoxy group-containing organic groups such as 1,4-epoxycyclohexylethyl, (meth) such as methacryloxypropyl group, methacryloxypropylmethyl group, methacryloxyethyl group, acryloxypropyl group, acryloxypropylmethyl group, acryloxyethyl group Trialkoxysilyl group-containing organic groups such as acryloyl group-containing organic groups, methoxysilylpropyl groups, methoxysilylpropylmethyl groups, methoxysilylethyl groups, triethoxysilylpropyl groups, triethoxysilylpropylmethyl groups, triethoxysilylethyl groups, And oxyalkyl groups, alkyloxyal Group, perfluorooxyalkyl group, perfluoroalkyloxy ether-containing organic group such as alkyl, phenyl, diphenyl group, and a phenyl-containing organic group such as bisphenol A residue.

  In formula (2), p is a positive integer of 2 to 10, preferably a positive integer of 2 to 6, more preferably a positive integer of 2 to 4, and further preferably 2.

（式（５）中、Ｒ³及びＲ⁴は上記の通りである。）
Among the components (D) represented by the formula (2), an organohydrogenpolysiloxane represented by the following formula (5) is particularly preferable.

(In formula (5), R ³ and R ⁴ are as described above.)

Examples of the organohydrogensiloxane derived from the formula (5) include the following organohydrogensiloxanes.

（式（３）中、Ｒ⁵は独立に炭素数１〜６のアルキル基であり、ｑは５〜１，０００の正の整数である。）
で示されるオルガノハイドロジェンポリシロキサンであり、高接着性を有しつつ、組成物の硬化後に低硬度を発現させる役割を有する。 [(E) component]
Component (E) is represented by the following general formula (3)

(In formula (3), R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and q is a positive integer of 5 to 1,000.)
The organohydrogenpolysiloxane represented by the formula (1) has a role of developing low hardness after curing of the composition while having high adhesiveness.

In formula (3), R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Of these, 90% or more is preferably a methyl group from the viewpoint of ease of synthesis and cost.

  In formula (3), q is a positive integer of 5 to 1,000, preferably a positive integer of 10 to 100. When the q value is less than 5, the organohydrogenpolysiloxane tends to be a volatile component, so it is not preferable to use it for electronic components. When the q value exceeds 1,000, the organohydrogenpolysiloxane has a high viscosity. It is not preferable because it becomes difficult to handle.

Examples of the organohydrogenpolysiloxane represented by the formula (3) include the following organohydrogenpolysiloxanes.

  The blending amount of the component (D) and the component (E) is the sum of the alkenyl group of the component (A) and the alkenyl group including the alkenyl group when the component (B) and component (C) include the alkenyl group. The ratio of the total number of Si-H groups in the (D) component and the (E) component to the number, that is, [total number of Si-H groups in the (D) component and (E) component] / [(A) component When the alkenyl group, the component (B), and the component (C) contain an alkenyl group, the total number of alkenyl groups including those alkenyl groups] is in the range of 0.6 to 1.5, preferably 0. This is an amount that is a value in the range of 7 to 1.4. When the ratio of the total number of Si-H groups to the total number of alkenyl groups is less than 0.6, the cured product cannot take a sufficient network structure and is not preferable because the necessary hardness cannot be obtained after curing. When it exceeds 1.5, the hardness becomes too high, which is not preferable.

  Further, the components (D) and (E) have a value in which [number of Si—H groups in the component (D)] / [number of Si—H groups in the component (E)] is in the range of 1 to 10, Is blended in an amount that gives a value in the range of 1.2-10. When the blending ratio of the number of Si-H groups of the component (D) to the number of Si-H groups of the component (E) is less than 1, it is not preferable because curing becomes insufficient after curing. This is not preferable because appropriate flexibility cannot be obtained after curing.

[(F) component]
The component (F) is a thermally conductive filler and has a role of imparting thermal conductivity to the composition (cured product). A conventionally well-known heat conductive filler can be used for a heat conductive filler. For example, aluminum powder, copper powder, silver powder, nickel powder, gold powder, alumina powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, boron nitride powder, silicon nitride powder, diamond powder, carbon powder, indium, and gallium Etc. Such heat conductive fillers may be used singly or in combination of two or more.

  The thermally conductive filler preferably has a thermal conductivity of 10 W / m · K or more. This is because if the thermal conductivity of the thermally conductive filler is less than 10 W / m · K, sufficient thermal conductivity cannot be imparted to the composition (cured product).

The average particle size of the thermally conductive filler is 0.1 to 100 μm, preferably 0.5 to 90 μm. When the average particle size is less than 0.1 μm, the particles are likely to aggregate together, resulting in poor fluidity. When the average particle size exceeds 100 μm, the fluidity of the particles themselves may be lowered. It is not preferable. The shape of the filler may be indefinite, spherical or any shape. The average particle diameter can be measured as a volume average value D ₅₀ (that is, a particle diameter or a median diameter when the cumulative volume is 50%) in particle size distribution measurement by a laser light diffraction method.

  (F) The compounding quantity of a component is 400-3,000 mass parts with respect to 100 mass parts of (A) component, Preferably it is 500-2,500 mass parts. When the blending amount of the component (F) is less than 400 parts by mass, the desired thermal conductivity cannot be imparted to the cured product, and when it exceeds 3,000 parts by mass, the composition does not become liquid and flows. It will be scarce.

[(G) component]
The component (G) is a platinum group metal catalyst. The platinum group metal catalyst is not particularly limited as long as it promotes the addition reaction between the alkenyl group such as the component (A) and the Si—H group of the component (D) and the component (E). Can be used. Among these, a catalyst selected from platinum and a platinum compound is preferable.

Examples of such catalysts include platinum group metals such as platinum (including platinum black), rhodium, palladium, H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaHPtCl ₆ · nH. ₂ O, KHPtCl ₆ · nH ₂ O, Na ₂ PtCl ₆ · nH ₂ O, K ₂ PtCl ₄ · nH ₂ O, PtCl ₄ · nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄ · nH ₂ O N in the formula is an integer of 0 to 6, preferably 0 or 6.) Platinum chloride, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and an olefin, A platinum group metal such as platinum black or palladium supported on a support such as alumina, silica or carbon, rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Luckinson's catalyst), platinum chloride, chloroplatinic acid, or a complex of chloroplatinate and a vinyl group-containing siloxane. These platinum group metal catalysts may be used alone or in combination of two or more.

  The blending amount of the component (G) is an effective amount as a catalyst, and may be an amount capable of proceeding the reaction between the component (A) and the like, the component (D) and the component (E), and depends on the desired curing rate. May be adjusted accordingly. In particular, the amount is from 0.1 to 7,000 ppm, preferably from 1 to 6,000 ppm, based on the mass of the component (A) converted to platinum group metal atoms. This is because when the blending amount of the component (G) is less than 0.1 ppm on a mass basis converted to a platinum group metal atom, there may be no effect as a catalyst, and even if it exceeds 7,000 ppm, the curing rate is particularly improved. This is because there are things that cannot be expected.

[(H) component]
The component (H) is a reaction control agent. The reaction control agent is blended in order to suppress the progress of the curing reaction at room temperature and extend the shelf life and pot life. Any reaction control agent may be used as long as it can suppress the catalytic activity of the component (G), and a known reaction control agent can be used. Examples thereof include acetylene compounds such as 1-ethynyl-1-cyclohexanol and 3-butyn-1-ol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds. Among these, acetylene alcohol that is not corrosive to metals is preferable.

  (H) The compounding quantity of a component is 0.01-5 mass parts with respect to 100 mass parts of (A) component, Preferably it is 0.05-1 mass part. When the blending amount of the reaction control agent is less than 0.01 parts by mass, sufficient shelf life and pot life may not be obtained. When the blending amount of the reaction control agent exceeds 5 parts by mass, the curability of the composition May decrease. The reaction control agent may be used after diluted with an organic solvent such as toluene, xylene, and isopropyl alcohol in order to improve dispersibility in the silicone resin.

[Other ingredients]
In addition to the above components (A) to (H), the heat conductive silicone potting composition of the present invention may contain known additives within a range that does not impair the object of the present invention. Examples of such additives include hindered phenolic antioxidants, reinforcing properties such as calcium carbonate, non-reinforcing fillers, polyethers as thixotropy improvers, and the like. Furthermore, you may add colorants, such as a pigment and dye, as needed.

[Method for producing thermally conductive silicone potting composition, etc.]
The manufacturing method of the heat conductive silicone potting composition of this invention is not restrict | limited in particular, What is necessary is just to follow a conventionally well-known method. That is, the thermally conductive silicone potting composition of the present invention can be obtained by mixing the components (A) to (H) and other components as necessary. If it is a 1 liquid type composition, it can be stored for a long time by refrigeration or freezing, and if it is a 2 liquid type composition part, it can be stored for a long time at normal temperature.

  The one-component type composition, for example, takes (A) component, (B) component, (C) component, and (F) component in a gate mixer (trade name: Planetary Mixer manufactured by Inoue Seisakusho Co., Ltd.). The mixture is heated and mixed at 150 ° C. for 1 hour. After cooling the mixture, component (H) is added and mixed at room temperature for 30 minutes. Thereafter, the component (G) is further added and mixed at room temperature for 30 minutes so as to be uniform. Then, (D) component and (E) component are added, and it is obtained by mixing for 30 minutes at room temperature.

  The two-component composition can be composed of any combination as long as only the combination of the component (A), the component (D), the component (E), and the component (G) does not coexist. For example, (A) component, (B) component, (C) component, and (F) component are taken into a gate mixer, heated and mixed at 150 ° C. for 1 hour, and after cooling, (G) component is added at room temperature. Mix for 30 minutes, and use the resulting composition as material A. In the gate mixer, take the components (A), (B), (C), and (F), mix by heating at 150 ° C. for 1 hour, After cooling, add component (H) and mix at room temperature for 30 minutes, then add component (D) and component (E), mix at room temperature for 30 minutes, and use the resulting composition as material B. , A material, B material 2 liquid type composition can be obtained.

  The heat conductive silicone potting composition preferably has a viscosity at 25 ° C. of 1 to 100 Pa · s, more preferably 5 to 50 Pa · s. When the viscosity at 25 ° C. is less than 1 Pa · s, the thermally conductive filler may easily settle, and when it exceeds 100 Pa · s, the fluidity may be poor. The viscosity is measured with a B-type rotational viscometer.

  Similarly, the thermally conductive silicone potting composition preferably has a thixotropic index value of not more than 1.3 after mixing and before curing. If the thixotropic index after mixing and before curing is more than 1.3, the fluidity may be poor, and it may be impossible to flow into every corner of the heat-generating component having a fine structure. Here, the thixotropic index is a value obtained by dividing the viscosity value measured at 10 rpm using a B-type rotational viscometer by the viscosity value measured at 20 rpm.

  The curing conditions for the thermally conductive silicone potting composition are not particularly limited, and may be the same conditions as those for conventionally known silicone gels. The thermally conductive silicone potting composition can also be cured by heat from the heat-generating component after being poured. Moreover, you may positively heat-harden. The heat curing conditions are 60 to 180 ° C., preferably 80 to 150 ° C., and 0.1 to 3 hours, preferably 0.5 to 2 hours.

  The cured product of the thermally conductive silicone potting composition obtained in this way usually exhibits a hardness of 60 or less as measured with a type A durometer as defined in JIS K 6253, thereby reducing the stress applied to the IC package as much as possible. It becomes suitable.

  That is, when such a heat conductive silicone potting composition is used as a filler in a case containing fine heat generating parts, it adheres well to the heat generating parts after curing and has a high thermal conductivity. Because it can maintain stable flexibility over time and does not peel off from heat-generating parts, it can efficiently transfer heat from the heat-generating parts to the case and reduce stress on the heat-generating parts. , Its reliability can be dramatically improved.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example.
Each component used in the Examples and Comparative Examples is shown below.

Component (A): A-1: Both ends are blocked with dimethylvinylsilyl groups, dimethylpolysiloxane having a viscosity at 25 ° C. of 0.06 Pa · s, A-2: Both ends are blocked with dimethylvinylsilyl groups, Dimethylpolysiloxane having a viscosity at 25 ° C. of 0.4 Pa · s

Component (B): B-1: Both ends blocked with trimethoxysilyl groups, dimethylpolysiloxane having a viscosity at 25 ° C. of 1 Pa · s B-2: Both ends blocked with trimethoxysilyl groups, 25 ° C. Dimethylpolysiloxane with a viscosity at 200 Pa · s

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

・Ｄ−２：下記式で示されるオルガノハイドロジェンシロキサン

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

D-2: Organohydrogensiloxane represented by the following formula

Component (E) E-1: Organohydrogenpolysiloxane represented by the following formula

(F) Component The heat conductive filler shown in the following (i) to (iv) is mixed so as to have the composition shown in Table 1 below, and a 5 L gate mixer (manufactured by Inoue Seisakusho Co., Ltd., trade name: 5 L planetary) F-1 to F-3 were obtained by mixing at room temperature for 30 minutes using a mixer.
(I) Alumina powder having an average particle size of 80 μm (ii) Alumina powder having an average particle size of 40 μm (iii) Alumina powder having an average particle size of 10 μm (iv) Alumina powder having an average particle size of 1.0 μm

Component (G): G-1: A dimethylpolysiloxane solution of a platinum-divinyltetramethyldisiloxane complex (dissolved in the same dimethylpolysiloxane as A-1 above, containing 1% as a platinum atom)

Component (H) H-1: 1-ethynyl-1-cyclohexanol H-2: triallyl isocyanurate

(Preparation of thermally conductive silicone potting composition)
(A) component, (B) component, (C) component is put into 5L gate mixer (Inoue Seisakusho Co., Ltd., trade name: 5L planetary mixer), and (F) component is shown in Table 2 or Table 3. The amount was added and mixed by heating at 140 ° C. for 2 hours. Next, the component (H) was added in the amount shown in Table 2 or Table 3, and mixed at room temperature for 30 minutes. Thereafter, the component (G) was further added at the blending amount shown in Table 2 or Table 3, and mixed at room temperature for 30 minutes so as to be uniform. Finally, the component (D) and the component (E) were added in the amounts shown in Table 2 or Table 3, and mixed at room temperature for 30 minutes so as to be uniform. Each physical property was measured by the method shown below about each obtained composition. The results are also shown in Table 2 and Table 3.

〔Thermal conductivity〕
The thermal conductivity at 25 ° C. of the thermally conductive silicone potting composition was measured using a hot disk method thermal property measuring device TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

〔viscosity〕
The viscosity at 25 ° C. of the thermally conductive silicone potting composition was measured at 20 rpm using a B-type viscometer.

〔hardness〕
The thermally conductive silicone potting composition was press cured at 120 ° C. for 10 minutes and further heated in an oven at 120 ° C. for 50 minutes. Three obtained silicone sheets having a thickness of 2.0 mm were stacked, and the hardness was measured with a type A durometer defined in JIS K 6253.

[Tensile strength, elongation at break]
The thermally conductive silicone potting composition was press cured at 120 ° C. for 10 minutes and further heated in an oven at 120 ° C. for 50 minutes. The tensile strength and elongation at break of the obtained silicone sheet having a thickness of 2.0 mm were measured according to JIS K 6251.

[Shear tensile adhesive strength]
Between a 1.0 mm thick aluminum (JIS H 4000 A1050P) plate and a 2.0 mm thick PPS (polyphenylene sulfide, Sustyl PPS GS-40, manufactured by Tosoh Corporation) plate, a thermally conductive silicone potting composition was In a state of being sandwiched so as to have a thickness of 2.0 mm and an adhesion area of 25 mm × 10 mm, the composition was cured by heating at 120 ° C. for 1 hour to prepare an adhesion test piece. The shear tensile adhesive strength of the obtained test piece was measured according to JIS K 6850.

[Flowability]
0.60 cm ^{3 of the} heat conductive silicone potting composition was taken and hung on an aluminum plate (JIS H 4000, 0.5 × 25 × 250 mm). Immediately after hanging, the aluminum plate is inclined at 28 degrees and allowed to stand in an atmosphere of 23 ° C. (± 2 ° C.). The sample was taken out after 23 ° C. (± 2 ° C.) × 1 hour, and the length of the thermally conductive silicone potting composition was measured from the flowing end to end.
The heat conductive silicone potting composition needs to have the above flowability of 100 mm or more when actually potting a part, preferably 120 mm or more, more preferably 150 mm or more. In addition, although the upper limit of fluidity | liquidity is so preferable that fluidity | liquidity is high, since a measurement limit is dependent on the length of an aluminum plate, a measurement upper limit becomes 240 mm here.

Claims (4)

(A) Organopolysiloxane having a viscosity at 25 ° C. of 0.01 to 100 Pa · s and having an alkenyl group bonded to at least two silicon atoms in one molecule: 100 parts by mass
(B) Organopolysiloxane having a viscosity of 0.01 to 100 Pa · s at 25 ° C. and having both ends blocked with trialkoxysilyl groups: 1 to 200 parts by mass,
(C) The following general formula (1)

(In formula (1), R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group, R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. (It is an integer of 100, and a is an integer of 1 to 3.)
An organopolysiloxane represented by: 1 to 200 parts by mass,
(D) The following general formula (2)

(In formula (2), R ³ is independently an alkyl group having 1 to 6 carbon atoms, and R ⁴ is independently bonded to a silicon atom via a hydrogen atom, or a carbon atom or a carbon atom and an oxygen atom, respectively. epoxy group, an acryloyl group, a methacryloyl group or trialkoxysilyl group, or an oxyalkyl group, alkyloxyalkyl group, perfluorooxyalkyl group, is a perfluoroalkyloxy group or a phenyl-containing monovalent organic group, with R ⁴ 3 or more of the groups shown are hydrogen atoms, and p is a positive integer of 2 to 10.)
An organohydrogenpolysiloxane represented by
(E) The following general formula (3)

(In formula (3), R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and q is a positive integer of 5 to 1,000.)
An organohydrogenpolysiloxane represented by
(F) Thermally conductive filler: 400 to 3,000 parts by mass, and (G) platinum group metal catalyst: containing a catalytic amount,
The blending amount of the component (D) and the component (E)
[Total number of Si-H groups in component (D) and component (E)] / [Alkenyl group in component (A) and (B) component and (C) if the component contains alkenyl groups, these alkenyl groups The total number of alkenyl groups, including the number of Si—H groups in component (D)] / [the number of Si—H groups in component (E)]. A heat conductive silicone potting composition characterized by being in the range of 1-10.   Furthermore, the heat conductive silicone potting composition of Claim 1 which contains 0.01-5.0 mass parts of (H) reaction control agent with respect to 100 mass parts of (A) component.   The heat conductive silicone potting composition according to claim 1 or 2, wherein the thixotropic index is 1.3 or less.   The thermally conductive silicone potting composition according to any one of claims 1 to 3, which gives a cured product having a value of 60 or less to JIS K 6253 with a specified type A durometer.