JP2019077845A - Thermally conductive silicone potting composition - Google Patents

Abstract

To provide a composition that includes a thermally conductive filler, has high fluidity and has a desired thermal conductivity after curing.SOLUTION: The composition includes: 100 pts.mass of (A) a polysiloxane having two or more alkenyl groups in one molecule and having a viscosity of 0.01 to 100 Pa s; 1 to 200 pts.mass of (B) a polysiloxane having both terminals each blocked with a trialkoxysilyl group and having a viscosity of 0.01 to 100 Pa s; 1 to 200 pts.mass of (C) an organopolysiloxane represented by formula (1); (D) an organohydrogensiloxane represented by formula (2); (E) an organohydrogensiloxane; (F) a thermally conductive filler; (G) a platinum group metal-based catalyst; (H) a reaction controlling agent; and (I) a hydrocarbon solvent and has a viscosity before curing of 100 Pa s or less and a fluidity of 100 mm or more.SELECTED DRAWING: None

Description

  The present invention relates to a thermally conductive silicone potting composition, and more specifically, by diluting with a highly volatile hydrocarbon-based solvent, the workability before curing is good, and after curing, it is desirable by evaporation of the diluting solvent. The present invention relates to a silicone potting composition that exhibits thermal conductivity.

With the rising awareness of global warming, the automotive industry has been developing environmentally friendly vehicles such as hybrid vehicles, plug-in hybrid vehicles, and electric vehicles for the purpose of reducing greenhouse gases, and aims to improve their fuel efficiency performance. Therefore, the inverter mounted on the vehicle has been enhanced and miniaturized.
Along with this, parts such as IC and reactor in the inverter are also miniaturized, and the amount of heat generation is also increasing. For such heat-generating parts, conventionally, a heat-conductive silicone composition such as a heat-conductive silicone grease, a heat-conductive silicone gel composition, a heat-conductive silicone potting composition and the like between the heat-generating part and the cooler By interposing objects, the cooling efficiency of the parts is improved to protect the parts.

For example, Patent Document 1 proposes a thermally conductive silicone composition comprising an organopolysiloxane, a hydrolyzable group-containing methylpolysiloxane, a thermally conductive filler, and a curing agent. Is difficult to adhere to parts having a microstructure.
Therefore, in Patent Document 2, a method in which the cooler and the heat generating component are assembled in advance, the highly conductive heat conductive silicone potting composition is poured therein, and the heat generating component and the cooler are thermally connected. It is disclosed.
However, as the miniaturization of parts has progressed with the recent miniaturization, the calorific value is increased, and a further improvement in thermal conductivity is also required for the thermally conductive silicone potting composition, however, Patent Document 2 When practical fluidity was maintained by the method of (1), the thermal conductivity of about 1.0 W / m · K was the limit.

  As a technique for solving this problem, Patent Document 3 proposes a silicone potting composition in which a large amount of a thermally conductive filler is contained to achieve a high thermal conductivity while achieving high flowability. However, even with this silicone composition, the thermal conductivity and fluidity are insufficient due to the further increase in power and miniaturization of the inverter, and thermal conductivity having both high thermal conductivity and high fluidity simultaneously Silicone potting compositions have been highly desirable.

Patent No. 3543663 gazette Patent No. 5304623 gazette JP, 2016-84378, A

  The present invention has been made in view of the above-mentioned circumstances, and although it contains a large amount of thermally conductive filler, it has high fluidity and can flow into a fine space, and after curing, it has a desired heat. It is an object of the present invention to provide a thermally conductive silicone potting composition having conductivity.

  The inventors of the present invention conducted intensive studies to achieve the above object, and as a result, a hydrocarbon compound having high volatility as a solvent of an addition reaction-curable thermally conductive silicone composition containing a large amount of thermally conductive filler By using a solvent, it was found that a thermally conductive silicone potting composition having high fluidity before curing and having a desired thermal conductivity after curing was obtained, and the present invention was completed.

（式（１）中、Ｒ¹は、互いに独立して非置換または置換の一価炭化水素基を表し、Ｒ²は、互いに独立して、アルキル基、アルコキシアルキル基、アルケニル基またはアシル基を表し、ｎは、２〜１００の整数であり、ａは、１〜３の整数である。）
（Ｄ）下記一般式（２）で示されるオルガノハイドロジェンポリシロキサン

（式（２）中、Ｒ³は、互いに独立して炭素数１〜６のアルキル基を表し、Ｒ⁴は、互いに独立して、水素原子、それぞれ炭素原子も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、メタクリロイル基もしくはトリアルコキシシリル基、エーテル含有一価有機基、またはフェニル基含有一価有機基を表すが、Ｒ⁴で示される基のうち３つ以上は水素原子である。ｐは、２〜１０の正の整数である。）
（Ｅ）下記一般式（３）で示されるオルガノハイドロジェンポリシロキサン：｛（Ｄ）成分と（Ｅ）成分の合計Ｓｉ−Ｈ基の個数｝／｛（Ａ）成分のアルケニル基の個数｝が０．６〜１．５の範囲、かつ｛（Ｄ）成分由来のＳｉ−Ｈの個数｝／｛（Ｅ）成分由来のＳｉ−Ｈの個数｝が１．０〜１０．０の範囲となる量

（式（３）中、Ｒ⁵は、互いに独立して炭素数１〜６のアルキル基を表し、ｑは、５〜１，０００の正の整数である。）
（Ｆ）熱伝導性充填材：４００〜３，０００質量部
（Ｇ）白金族金属系触媒
（Ｈ）アセチレンアルコール化合物、窒素化合物、有機りん化合物、オキシム化合物および有機クロロ化合物より選択される反応制御剤：０．０１〜５質量部
（Ｉ）（Ａ）〜（Ｈ）成分を分散または溶解可能で、沸点が１５０〜３５０℃の炭化水素系溶剤：０．１〜１００質量部
を含み、硬化前の２３℃の粘度が１００Ｐａ・ｓ以下であり、２３℃での流れ性が１００ｍｍ以上で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
を提供する。 That is, the present invention
1. (A) Organopolysiloxane having at least two alkenyl groups in one molecule and having a viscosity of 0.01 to 100 Pa · s at 25 ° C .: 100 parts by mass (B) a viscosity of 0.01 to 100 Pa · at 25 ° C. organopolysiloxane having both ends blocked with a trialkoxysilyl group: 1 to 200 parts by mass (C) organopolysiloxane represented by the following general formula (1): 1 to 200 parts by mass

(In formula (1), R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group, R ² independently of each other represents an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group N is an integer of 2 to 100, and a is an integer of 1 to 3.)
(D) an organohydrogenpolysiloxane represented by the following general formula (2)

(In the formula (2), R ³ independently represents an alkyl group having 1 to 6 carbon atoms, and R ⁴ independently of each other via a hydrogen atom, a carbon atom or a carbon atom and an oxygen atom, respectively An epoxy group bonded to a silicon atom, an acryloyl group, a methacryloyl group or a trialkoxysilyl group, an ether-containing monovalent organic group, or a phenyl group-containing monovalent organic group is represented, but three of the groups represented by R ⁴ The above is a hydrogen atom, and p is a positive integer of 2 to 10.)
(E) Organohydrogenpolysiloxane represented by the following general formula (3): {total number of Si-H groups of (D) component and (E) component} / {number of alkenyl groups of (A) component} The range of 0.6 to 1.5 and {number of Si-H derived from the component (D)} / {number of Si-H derived from the component (E)} is in the range of 1.0 to 10.0 amount

(In Formula (3), R ⁵ independently represents an alkyl group having 1 to 6 carbon atoms, and q is a positive integer of 5 to 1,000.)
(F) Thermally conductive filler: 400 to 3,000 parts by mass (G) Platinum group metal catalyst (H) Acetylene alcohol compound, nitrogen compound, organic phosphorus compound, oxime compound and organic chloro compound Agent: 0.01 to 5 parts by mass Hydrophilic solvent capable of dispersing or dissolving components (I) to (H) and having a boiling point of 150 to 350 ° C .: 0.1 to 100 parts by mass, and cured A thermally conductive silicone potting composition is provided, which has a viscosity of not more than 100 Pa · s and a flowability at 23 ° C. of not less than 100 mm.

The thermally conductive silicone potting composition of the present invention has high fluidity before curing, can flow into fine spaces, and exhibits desirable thermal conductivity by volatilization of the solvent after curing.
For this reason, the composition of the present invention is effective for potting, for example, when a component having a fine structure such as a transformer is fixed to a cooler, and such a member has high thermal conductivity after curing. It is possible to transfer the heat of the part to the cooler efficiently at a rate.

Hereinafter, the present invention will be described in more detail.
The thermally conductive silicone potting composition according to the present invention cures at room temperature or under heating and adheres to a metal, an organic resin or the like, and (A) an organohaving at least two alkenyl groups in one molecule. Polysiloxane, (B) Organopolysiloxane blocked at both ends with trialkoxysilyl group, (C) Organopolysiloxane blocked at one end with alkoxysilyl group, etc., (D) Cyclic organohydrogensiloxane, (E ) Linear organohydrogensiloxanes having Si-H groups at both ends, (F) heat conductive filler, (G) platinum group metal based catalyst, (H) reaction control agent, (I) high volatility It contains a hydrocarbon solvent.

(1) Component (A) Component (A) has a viscosity of 0.01 to 100 Pa · s, preferably 0.06 to 10 Pa · s at 25 ° C., and bonds to at least 2 silicon atoms in one molecule Organopolysiloxanes having alkenyl groups. If the viscosity at 25 ° C. is less than 0.01 Pa · s, the storage stability of the composition deteriorates, and if it exceeds 100 Pa · s, high flowability can not be ensured. In addition, the said viscosity is a measured value (it makes the same hereafter) by a rotational viscometer.
Such 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 is also linear or branched. Or mixtures of two or more organopolysiloxanes having different viscosities.

Although the alkenyl group couple | bonded with a silicon atom is not specifically limited, A C2-C10 alkenyl group is preferable and a C2-C8 alkenyl group is more preferable.
Specific examples thereof include vinyl, allyl, 1-butenyl, 1-hexenyl group and the like. Among these, vinyl groups are preferable in terms of easiness of synthesis and cost.
The alkenyl group may be present at either end or in the middle of the molecular chain of the organopolysiloxane, but from the viewpoint of flexibility, it is preferred to be present only at both ends.

The organic group other than the alkenyl group bonded to the silicon atom is not particularly limited, but is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, and more preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms .
Specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-hexyl and n-dodecyl; aryl groups such as phenyl; and 2-phenylethyl and 2-phenylpropyl Aralkyl groups and the like can be mentioned.
In addition, part or all of the hydrogen atoms of these hydrocarbon groups may be substituted with a halogen atom such as chlorine, fluorine or bromine, and as a specific example thereof, a fluoromethyl group, a bromoethyl group, a chloromethyl group And halogen-substituted monovalent hydrocarbon groups such as 3,3,3-trifluoropropyl and the like.
Among these, in view of easiness of synthesis and cost, it is preferable that 90 mol% or more is a methyl group.
Accordingly, the component (A) is particularly preferably dimethylpolysiloxane which is capped at both ends with a dimethylvinylsilyl group. The component (A) may be used alone or in combination of two or more.

(2) Component (B) 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. It is an organopolysiloxane end-capped with a trialkoxysilyl group, 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 the fluidity deteriorates. In addition, each alkoxy group forming both terminal trialkoxysilyl groups is preferably independently of one another one having 1 to 6 carbon atoms, more preferably one having 1 to 4 carbon atoms, and, for example, a trimethoxysilyl group or triethoxysilyl group Etc.

  There is no particular limitation except the structure of both ends in the organopolysiloxane of the component (B), and as a substituent bonded to a silicon atom other than both ends, methyl, ethyl, n-propyl, n-butyl, n-pentyl, Alkyl groups such as n-hexyl group; cycloalkyl groups such as cyclohexyl group; alkenyl groups such as vinyl and allyl group; monovalent hydrocarbon groups having 1 to 8 carbon atoms such as aryl groups such as phenyl and tolyl group; A halogenated hydrocarbon group such as a chloromethyl group or a trifluoromethyl group in which a part or all of hydrogen atoms of a monovalent hydrocarbon group is substituted with a halogen atom such as a chlorine atom, a fluorine atom or a bromine atom is exemplified.

  As a suitable (B) component, what is shown by following formula (4) is mentioned, for example.

In formula (4), R ⁶ independently represents an alkyl group having 1 to 4 carbon atoms, and specific examples thereof include methyl, ethyl, n-propyl and n-butyl groups. Among these, a methyl group and an ethyl group are preferable.
R ⁷ each independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and specific examples thereof include methyl, ethyl, n-propyl, n-butyl, n-pentyl and n Alkyl groups such as hexyl and n-heptyl groups; monovalent hydrocarbon groups such as aryl groups such as phenyl and tolyl groups; and part or all of hydrogen atoms of these monovalent hydrocarbon groups as chlorine atoms or fluorine atoms And a halogenated hydrocarbon group such as chloromethyl group, 3-chloropropyl group and trifluoromethyl group substituted by a halogen atom such as bromine atom. Among these, methyl and ethyl are particularly preferable.
Further, r is a number such that the viscosity at 25 ° C. of the organopolysiloxane represented by the formula (4) is 0.01 to 100 Pa · s, and is preferably an integer of 1 to 100.

Although the compounding quantity of (B) 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. If it is less than 1 part by mass, the composition can not be provided with fluidity, and if it exceeds 200 parts by mass, the composition has a high viscosity.
The component (B) may be used alone or in combination of two or more.

(3) Component (C) The component (C) is an organopolysiloxane represented by the following general formula (1), and has the role of imparting fluidity by reducing the viscosity of the composition.

（式（１）中、Ｒ¹は、互いに独立して非置換または置換の一価炭化水素基を表し、Ｒ²は、互いに独立して、アルキル基、アルコキシアルキル基、アルケニル基またはアシル基を表し、ｎは、２〜１００の整数であり、ａは、１〜３の整数である。）

(In formula (1), R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group, R ² independently of each other represents an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group N is an integer of 2 to 100, and a is an integer of 1 to 3.)

The monovalent hydrocarbon group for R ¹ is not particularly limited, but is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, and more preferably a monovalent hydrocarbon group having 1 to 6 carbon atoms, A C1-C3 monovalent hydrocarbon group is more preferable.
Specific examples of the monovalent hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkyl halide and the like.
The alkyl group may be linear, branched or cyclic, and specific examples thereof include linear alkyl groups such as methyl, ethyl, n-propyl, n-hexyl and n-octyl groups; isopropyl, Examples thereof include branched alkyl groups such as isobutyl, tert-butyl and 2-ethylhexyl groups; and cyclic alkyl groups such as cyclopentyl and cyclohexyl groups.
Specific examples of the alkenyl group include vinyl, allyl, 1-butenyl, 1-hexenyl group and the like.
Specific examples of the aryl group include phenyl group and tolyl group.
Specific examples of the aralkyl group include 2-phenylethyl group, 2-methyl-2-phenylethyl group and the like.
Specific examples of the halogenated alkyl group include 3,3,3-trifluoropropyl group, 2- (nonafluorobutyl) ethyl group, 2- (heptadecafluorooctyl) ethyl group and the like.
Among these, R ¹ is preferably a methyl group, a phenyl group or a vinyl group.
Examples of the alkyl group and alkenyl group for R ² include the same groups as those exemplified for R ¹ above, and examples of the alkoxyalkyl group include methoxyethyl and methoxypropyl groups, and the like. For example, acetyl, octanoyl and the like can be mentioned.
Among these, R ² is preferably an alkyl group, more preferably a methyl group or an ethyl group.
Although said n is an integer of 2-100, Preferably it is an integer of 5-80.
The above a is an integer of 1 to 3, but is preferably 3.

Although the viscosity at 25 degrees C of (C) component is 0.005-10 Pa.s normally, 0.005-1 Pa.s is preferable. If the viscosity at 25 ° C. is less than 0.005 Pa · s, oil bleeding from the composition is likely to occur, which may cause a decrease in adhesive strength over time, and when the viscosity exceeds 10 Pa · s, the viscosity is increased. There is a possibility that the liquidity may be reduced.
Although the following compounds can be mentioned as a specific example of organopolysiloxane represented by Formula (2), It is not limited to this.

Although the compounding quantity of (C) component is not specifically limited, It is 1-200 mass parts with respect to 100 mass parts of (A) component, Preferably it is 10-180 mass parts. If the amount is less than 1 part by mass, a low viscosity composition can not be obtained, and if it exceeds 200 parts by mass, physical properties after curing become poor.
The component (C) may be used alone or in combination of two or more.

(4) Component (D) The component (D) is a cyclic organohydrogenpolysiloxane represented by the following general formula (2), and also acts as a curing agent for the composition while having high adhesion.

（式（２）中、Ｒ³は、互いに独立して炭素数１〜６のアルキル基を表し、Ｒ⁴は、互いに独立して、水素原子、それぞれ炭素原子も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、メタクリロイル基もしくはトリアルコキシシリル基、エーテル含有一価有機基、またはフェニル基含有一価有機基を表すが、Ｒ⁴で示される基のうち３つ以上は水素原子である。ｐは、２〜１０の正の整数である。）

(In the formula (2), R ³ independently represents an alkyl group having 1 to 6 carbon atoms, and R ⁴ independently of each other via a hydrogen atom, a carbon atom or a carbon atom and an oxygen atom, respectively An epoxy group bonded to a silicon atom, an acryloyl group, a methacryloyl group or a trialkoxysilyl group, an ether-containing monovalent organic group, or a phenyl group-containing monovalent organic group is represented, but three of the groups represented by R ⁴ The above is a hydrogen atom, and p is a positive integer of 2 to 10.)

As a C1-C6 alkyl group of R < ³ >, a methyl, an ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl group etc. are mentioned. Among them, in view of easiness of synthesis and cost, it is preferable that 90 mol% or more is a methyl group.
As described above, three or more of the groups represented by R ⁴ are hydrogen atoms, but when three or more are not hydrogen atoms, react with an alkenyl group such as component (A) to form a crosslinked structure Can not
Moreover, as a specific example of groups other than a hydrogen atom in R ⁴ , epoxy group-containing compounds such as 3-glycidoxypropyl, 3-glycidoxypropylmethyl, 3-glycidoxyethyl, 3,4-epoxycyclohexylethyl and the like Organic groups; (meth) acryloyl group-containing organic groups such as methacryloxypropyl, methacryloxypropylmethyl, methacryloxyethyl, acryloxypropyl, acryloxypropyl methyl, acryloxyethyl groups; methoxysilylpropyl, methoxysilylpropylmethyl, methoxy Trialkoxysilyl group-containing organic groups such as silylethyl, triethoxysilylpropyl, triethoxysilylpropylmethyl and triethoxysilylethyl groups; oxyalkyl groups, alkyloxyalkyl groups, perfluorooxyalkyl groups, perfluoro groups Ether-containing organic group such as an alkyloxyalkyl; phenyl, diphenyl, phenyl-containing organic group such as bisphenol A residues.
Although said p is a positive integer of 2-10, Preferably it is a positive integer of 2-6, More preferably, it is a positive integer of 2-4, More preferably, it is 2.
Among the components (D) represented by the formula (2), organohydrogensiloxanes of the following formula (5) are particularly preferable.

（式（５）中、Ｒ⁴およびＲ⁵は上記と同じ意味を表す。）

(In formula (5), R ⁴ and R ⁵ have the same meaning as described above.)

Although the thing shown by a following formula is mentioned as a specific example of the organohydrogen siloxane shown by Formula (5), It is not limited to these.
The component (D) may be used alone or in combination of two or more.

(5) Component (E) The component (E) is an organohydrogenpolysiloxane represented by the following general formula (3) and has a role of making the composition after curing flexible.

（式（３）中、Ｒ⁵は、互いに独立して炭素数１〜６のアルキル基を表し、ｑは、５〜１，０００の正の整数である。）

(In Formula (3), R ⁵ independently represents an alkyl group having 1 to 6 carbon atoms, and q is a positive integer of 5 to 1,000.)

Specific examples of the alkyl group having 1 to 6 carbon atoms of R ⁵ include methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl groups. From the viewpoint of easiness of synthesis, it is preferable that 90 mol% or more is a methyl group.
Also, q is a positive integer of 5 to 1,000, preferably 10 to 100. If the value of q is less than 5, the organohydrogenpolysiloxane tends to be a volatile component and is unsuitable for electronic parts. On the other hand, when the value of q exceeds 1,000, the viscosity of the organohydrogenpolysiloxane becomes high, and the fluidity of the composition becomes poor.
Examples of the organohydrogenpolysiloxane represented by the formula (3) include the following organohydrogenpolysiloxanes.
The component (E) may be used alone or in combination of two or more.

  The compounding amounts of the (D) component and the (E) component are [total number of Si-H groups of (D) component and (E) component] / [alkenyl group of (A) component, (B) component, ( C) When the component contains an alkenyl group, the synthetic number of the alkenyl group including the alkenyl group] is a value in the range of 0.6 to 1.5, preferably a value in the range of 0.7 to 1.4 The amount is If the ratio of the total number of Si-H groups to the total number of alkenyl groups is less than 0.6, a sufficient network structure can not be obtained after curing, and the required hardness can not be obtained. On the other hand, if it exceeds 1.5, the hardness becomes too high, which may give an excessive stress to the electronic component.

  Furthermore, (D) and (E) components have a {number of Si-H groups derived from component (D)} / {number of Si-H groups derived from component (E)} of 1.0 to 10.0. It is preferable to mix | blend in the quantity which becomes a value which exists in the range of 1.2-10 preferably. If the ratio of the number of Si-H groups of component (D) to the number of Si-H groups of component (E) is less than 1.0, a sufficient stitch structure can not be obtained after curing, and curing is If the value is more than 10.0, the hardness may be too high after curing, and the electronic component may be excessively stressed.

(6) Component (F) The component (F) is a thermally conductive filler, has a role of imparting thermal conductivity to the composition, and a conventionally known thermally conductive filler can be used.
Specific examples thereof include 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, gallium, etc. may be mentioned, and these may be used alone or in combination of two or more.
The average particle size of the thermally conductive filler is not particularly limited, but is preferably 0.1 to 100 μm, and more preferably 0.5 to 90 μm. When the average particle size is less than 0.1 μm, the particles may be easily aggregated to cause poor fluidity, and when it exceeds 100 μm, the fluidity of the particles may be lowered. The shape of the filler is arbitrary and may be irregular or spherical. The average particle diameter shall be measured as the volume-based median diameter in the particle size distribution measurement by laser diffraction method (D _50).
The heat conductive filler used in the present invention is preferably one having a thermal conductivity of 10 W / m · K or more, in consideration of providing a sufficient thermal conductivity to the composition.

  Although the compounding quantity of (F) 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 compounding amount of the component (D) is less than 400 parts by mass, a desired thermal conductivity can not be imparted to the cured product, and when it exceeds 3,000 parts by mass, the composition does not become liquid. It becomes less liquid.

(7) (G) Component The (G) component is a platinum group metal catalyst.
The platinum group metal-based catalyst may be any known catalyst as long as it promotes the addition reaction between alkenyl groups such as component (A) and the Si-H groups of components (D) and (E). Among them, catalysts selected from platinum and platinum compounds are preferred, although they can be used.
Specific examples of the catalyst include platinum (including platinum black), platinum group metals such as rhodium and palladium, H ₂ PtCl ₄ .nH ₂ O, H ₂ PtCl ₆ .H 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 (wherein the formula is n is an integer of 0 to 6, preferably 0 or 6.) platinum chloride such as chloroplatinic acid, chloroplatinic acid salt, alcohol-modified chloroplatinic acid, chloroplatinic acid-olefin complex, platinum black , Platinum group metals such as palladium supported on a carrier such as alumina, silica, carbon, etc., rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkinson catalyst), platinum chloride, white chloride Examples thereof include complexes of auric acid or chloroplatinic acid salt and a vinyl group-containing siloxane, and these may be used alone or in combination of two or more.

The compounding amount of the component (G) is an effective amount as a catalyst, and may be an amount capable of advancing the reaction between the components (A) and (B) and the component (E), depending on the desired curing rate. It may be adjusted appropriately.
In particular, an amount of 0.1 to 7,000 ppm is preferable, and an amount of 1 to 6,000 ppm is more preferable, with respect to the mass of the component (A), on a mass basis converted to platinum group metal atoms. When the compounding amount of the component (F) is in the above range, more efficient catalytic action can be expected.

(8) (H) Component The (H) component is a reaction control agent. The reaction control agent is formulated to suppress the curing reaction at room temperature and to extend 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 conventionally known reaction control agents can be used.
Specific examples thereof include acetylene alcohol compounds such as 1-ethynyl-1-cyclohexanol and 3-butyn-1-ol, various nitrogen compounds, organic phosphorus compounds, oxime compounds, organic chloro compounds and the like. The species may be used alone, or two or more species may be used in combination. Among these, acetylene alcohol compounds having no corrosiveness to metals are preferable.

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

(9) Component (I) The component (I) is a volatile solvent having the ability to disperse or dissolve the components (A) to (H) and having a boiling point of 150 to 350 ° C. The solvent is not particularly limited as long as it is, but isoparaffinic solvents are preferable from the viewpoint of workability and health.
By blending the component (I), the solvent of the component (I) is volatilized to obtain a composition having a desired thermal conductivity in the process of heat curing of the composition by heat from a heating furnace or a heat-generating component. be able to. If the boiling point of the volatile solvent is less than 150 ° C., volatilization may be too fast and the composition may have poor flow during operation, while if the boiling point exceeds 350 ° C. the silicone potting composition The solvent tends to remain inside, and the thermal conductivity decreases.

  Specific examples of hydrocarbon solvents include IP Solvent 1620 (isoparaffin solvent) manufactured by Idemitsu Kosan Co., Ltd., IP Solvent 2028 (isoparaffin solvent), IP solvent 2835 (isoparaffin solvent), etc. It may be used alone or in combination of two or more.

  Although the compounding quantity of (I) component is 0.1-100 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-80 mass parts, More preferably, it is 5-50.

A known additive may be added to the thermally conductive silicone potting composition of the present invention as an optional component other than the components (A) to (I) within the range that does not impair the object of the present invention.
In addition, reinforcing agents such as hindered phenolic antioxidants, calcium carbonate and the like, non-reinforcing fillers such as calcium carbonate, and pigments such as pigments and dyes can also be added.

The method of producing the thermally conductive silicone potting composition of the present invention is not particularly limited, and may be in accordance with conventionally known methods, for example, components (A) to (F) and, if necessary, other components. The components may be mixed, and the form thereof may be one-pack type or two-pack type.
In addition, if it is 1 liquid type, it can be stored for a long period by refrigerated or frozen, and if it is 2 liquid type, it can be stored at normal temperature for a long time.

  For the composition of the one-pack type, for example, the components (A), (B), (C), and (F) are introduced into a gate mixer (product name: Planetary Mixer, manufactured by Inoue Seisakusho Co., Ltd.) The mixture is heated and mixed at 150 ° C. for 1 hour and then cooled. Thereafter, the (H) component is added and mixed for 30 minutes at room temperature. Further, the component (G) is added and mixed at room temperature for 30 minutes so as to be uniform. Then, it is obtained by adding (D) component, (E) component, and (I) component, and mixing for 30 minutes at room temperature.

  On the other hand, the two-pack composition can be composed of any combination, as long as the combination of the components (A), (D), (E) and (G) does not coexist. For example, components (A), (B), (C), and (F) are charged into a gate mixer, mixed by heating at 150 ° C. for 1 hour, and then cooled. Thereafter, the component (G) is added and mixed at room temperature for 30 minutes to obtain a composition obtained as material A. Next, components (A), (B), (C), and (F) are charged into a gate mixer, mixed by heating at 150 ° C. for 1 hour, and then cooled. Thereafter, the (H) component is added and mixed for 30 minutes at room temperature, and the (D) component, the (E) component, and the (I) component are further added and mixed for 30 minutes at room temperature. Thereby, the composition of 2 liquid type of A material and B material 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 be easily sedimented, and when it exceeds 100 Pa · s, the fluidity may be poor. The viscosity is measured with a B-type rotational viscometer.
In addition, the thermally conductive silicone potting composition preferably has a thixotropic index value of 1.3 or less after mixing and before curing. If the thixotropic index before curing after mixing is more than 1.3, the flowability may be poor and it will be difficult to flow into the heat-generating component having a microstructure. Here, the thixotropic index is a value obtained by dividing the viscosity value measured at 10 rpm using a B-type viscometer by the viscosity value measured at 20 rpm.

  The heat conductive silicone potting composition preferably has a flowability of 100 mm or more at 23 ° C. whose measurement method will be described in detail in the following examples. Where a component having a microstructure such as a transformer is attached to the cooler, it is preferably 120 mm or more when pouring the silicone potting composition. The upper limit of the flowability is preferably as high as possible, but since the measurement limit depends on the length of the aluminum plate, the upper limit of measurement here is 240 mm.

The curing conditions of the thermally conductive silicone potting composition of the present invention are not particularly limited, and may be the same as conventionally known silicone gels.
The heat conductive silicone potting composition may be cured by heat from the heat generating component after being poured in, or may be actively heat cured. The heat curing conditions are preferably 60 to 180 ° C., more preferably 80 to 150 ° C., preferably 0.1 to 3 hours, more preferably 0.5 to 2 hours.

  When the heat conductive silicone potting composition of the present invention is used as a filler in a case containing a minute heat generating component, it has high fluidity and flows into every minute structure of the fine structure, and after curing, the heat generating component etc. Since it can be adhered well to have high thermal conductivity, the heat of the heat-generating component can be efficiently transmitted to the case, and the reliability thereof can be dramatically improved.

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples, but the present invention is not limited to the following examples.
Each component used in the Example and the comparative example is shown below.

(A) Component A-1: Both ends capped with dimethylvinylsilyl group, dimethylpolysiloxane having a viscosity of 0.06 Pa · s at 25 ° C. A-2: Both ends capped with dimethylvinylsilyl group C., dimethylpolysiloxane having a viscosity of 0.4 Pa · s at 25 ° C .: A-3: dimethylpolysiloxane blocked at both ends with a dimethylvinylsilyl group and having a viscosity of 0.6 Pa · s at 25 ° C.

(B) Component B-1: dimethylpolysiloxane which is blocked at both ends with a trimethoxysilyl group and has a viscosity of 1 Pa · s at 25 ° C.

(C) Component C-1: an organopolysiloxane represented by the following formula

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

D-2: Organohydrogensiloxane represented by the following formula

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

(F) Component F-1: Alumina powder having an average particle diameter of 80 μm F-2: Alumina powder having an average particle diameter of 40 μm F-3: Alumina powder having an average particle diameter of 10 μm F-4: Average particle diameter 1. 0 μm alumina powder

(G) Component G-1: Dimethylpolysiloxane solution of platinum-divinyl tetramethyldisiloxane complex (dissolved in the same dimethylpolysiloxane as A-3 above, containing 1% as platinum source)

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

(I) Component I-1: IP solvent 1620 (iso-paraffin based solvent, manufactured by Idemitsu Kosan Co., Ltd.)
I-2: IP solvent 2028 (iso-paraffin based solvent, manufactured by Idemitsu Kosan Co., Ltd.)
I-3: IP solvent 2835 (iso-paraffin based solvent, manufactured by Idemitsu Kosan Co., Ltd.)

[Examples 1 to 5, Comparative Examples 1 and 2]
The components (A) to (I) were mixed as follows to obtain a silicone potting composition.
A component, components (B), (C), (C) and (F) are added at a blending amount shown in Table 1 to a 5 L gate mixer (Inoue Mfg. Co., Ltd., trade name; 5 L planetary mixer) and 150 ° C. Heat mixed for 2 hours. After cooling the mixture, the (G) component was added and mixed at room temperature for 30 minutes so as to be uniform. Next, the (H) component was added and mixed at room temperature for 30 minutes so as to be uniform. Finally, component (D), component (E) and component (I) were added and mixed at room temperature for 30 minutes.
The following physical properties of the obtained composition were measured. The results are shown in Table 2.

[1] Thermal Conductivity The thermal conductivity of the cured product of the thermally conductive silicone potting composition at 25 ° C. was measured using a hot disk method thermal physical property measuring apparatus TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.
[2] Viscosity The viscosity at 25 ° C. of the thermally conductive silicone potting composition was measured at 20 rpm using a B-type viscometer.
[3] Tikisolotopic Index It was calculated by dividing the viscosity value measured at 10 rpm using a B-type viscometer of the thermally conductive silicone potting composition by the viscosity value measured at 20 rpm.
[4] Hardness The thermally conductive silicone potting composition was press-cured at 120 ° C. for 10 minutes at a thickness of 2.0 mm and further heated in an oven at 120 ° C. for 50 minutes. Three sheets of the obtained silicone sheet were stacked, and the hardness was measured by a type A durometer specified in JIS K 6253.
[5] Tensile Strength, Elongation at Break The heat conductive silicone potting composition was press cured at a thickness of 2.0 mm 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 were measured according to JIS K 6251.
[6] Shear tensile adhesive strength A thermally conductive silicone potting composition is sandwiched between an aluminum (JIS H 4000 A1050P) plate having a thickness of 1.0 mm so as to have a thickness of 2.0 mm and an adhesive area of 25 mm × 10 mm. Then, the silicone potting composition was cured by heating at 120 ° C. for 1 hour to prepare an adhesive test piece. The shear tensile adhesive strength of the obtained test piece was measured according to JIS K 6850.
[7] Flowability 0.60 cc of the thermally conductive silicone potting composition was weighed and dropped onto an aluminum plate (JIS H 4000, thickness 0.5 × width 25 × length 400 mm). Immediately after dripping, the aluminum plate was inclined at 28 ° and left to stand under an atmosphere of 23 ° C. (± 2 ° C.) for 1 hour. The length of the heat conductive silicone potting composition after standing was measured from the end to the end which flowed.

  As shown in Table 2, it can be seen that the thermally conductive silicone potting composition of the present invention has good flowability before curing and good physical properties after curing.

Claims (1)

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

(In formula (1), R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group, R ² independently of each other represents an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group N is an integer of 2 to 100, and a is an integer of 1 to 3.)
(D) an organohydrogenpolysiloxane represented by the following general formula (2)

(In the formula (2), R ³ independently represents an alkyl group having 1 to 6 carbon atoms, and R ⁴ independently of each other via a hydrogen atom, a carbon atom or a carbon atom and an oxygen atom, respectively An epoxy group bonded to a silicon atom, an acryloyl group, a methacryloyl group or a trialkoxysilyl group, an ether-containing monovalent organic group, or a phenyl group-containing monovalent organic group is represented, but three of the groups represented by R ⁴ The above is a hydrogen atom, and p is a positive integer of 2 to 10.)
(E) Organohydrogenpolysiloxane represented by the following general formula (3): {total number of Si-H groups of (D) component and (E) component} / {number of alkenyl groups of (A) component} The range of 0.6 to 1.5 and {number of Si-H derived from the component (D)} / {number of Si-H derived from the component (E)} is in the range of 1.0 to 10.0 amount

(In Formula (3), R ⁵ independently represents an alkyl group having 1 to 6 carbon atoms, and q is a positive integer of 5 to 1,000.)
(F) Thermally conductive filler: 400 to 3,000 parts by mass (G) Platinum group metal catalyst (H) Acetylene alcohol compound, nitrogen compound, organic phosphorus compound, oxime compound and organic chloro compound Agent: 0.01 to 5 parts by mass Hydrophilic solvent capable of dispersing or dissolving components (I) to (H) and having a boiling point of 150 to 350 ° C .: 0.1 to 100 parts by mass, and cured A thermally conductive silicone potting composition characterized in that the viscosity at 23 ° C. before is 100 Pa · s or less, and the flowability at 23 ° C. is 100 mm or more.