WO2021149431A1

WO2021149431A1 - Thermally conductive silicone adhesive composition

Info

Publication number: WO2021149431A1
Application number: PCT/JP2020/047621
Authority: WO
Inventors: 展明松本; 晶坂本; 太一北川
Original assignee: 信越化学工業株式会社
Priority date: 2020-01-21
Filing date: 2020-12-21
Publication date: 2021-07-29
Also published as: JP2021113289A; JP7290118B2

Abstract

This thermally conductive silicone adhesive composition comprises: (A) an organopolysiloxane which has an alkenyl group and does not have an organoxysilyl group; (B) an organopolysiloxane blocked with trialkoxysilyl groups at both terminals; (C) an organopolysiloxane blocked with an alkoxy group at one terminal; (D) a predetermined cyclic organohydrogensiloxane; (E) a predetermined linear organohydrogen polysiloxane; (F) a thermally conductive filling material; and (G) a platinum group metal-based catalyst, wherein [total number of Si-H groups]/[total number of alkenyl groups] is a predetermined ratio, and [number of Si-H groups in (D) component]/[number of Si-H groups in (E) component] is a predetermined ratio.

Description

Thermally conductive silicone adhesive composition

The present invention relates to a thermally conductive silicone adhesive composition.

In recent years, technological development related to electrification, automation, and energy saving has become very active in the field of car electronics. For example, parts such as a transformer and a choke coil are mounted in an in-vehicle charger required for electrification, and these transformers and choke coils are composed of a core and a coil. Since heat is generated from the core and coil, it is necessary to remove this heat, but the heat generating part has a complicated and complicated shape, and it is difficult to secure a heat dissipation path.

Therefore, the transformer parts composed of the core and coil are inserted into the heat dissipation case, and the highly fluid heat conductive silicone potting composition is poured into the heat dissipation case to make every corner of the gap between the heat generation parts and the heat dissipation case. A method of burying and connecting a heat generating component and a cooling component to secure a heat dissipation path is used (Patent Documents 1 to 3).
In addition, since a large amount of heat is also generated from the electronic component for control, it is necessary to remove the heat in order to prevent the electronic component from failing. The mounting location of electronic components varies depending on the purpose of function, and it can be a harsh environment.

Therefore, it is important to select a material that will not fall out from the gap between the heat generating parts and the heat dissipation case even in a harsh environment. For example, when it is not desired to give stress to electronic components on a printed circuit board, it is common to select a heat-dissipating gel or a low-hardness thermally conductive silicone adhesive (Patent Documents 4 to 6). Further, a condensation-type low-hardness thermally conductive silicone material having a low viscosity at the time of discharge, which facilitates application and thickens with moisture, has also been proposed (Patent Document 7). However, none of the above-mentioned materials had sufficient adhesive strength.

On the other hand, although high-hardness thermally conductive silicone adhesives (Patent Documents 8 and 9) have excellent adhesive strength, if they cannot follow the movement of heat-dissipating parts due to temperature changes, the adhesive cracks and a heat-dissipating path is secured. There was a problem that it could not be done. This is partly due to the lack of elongation of the high hardness thermally conductive silicone adhesive, but in general it is necessary to soften the material in order to obtain a material with high elongation, and as a result, the adhesive strength is increased. There was a technical problem that it was lowered and easily peeled off.

Japanese Patent No. 5304623 Japanese Patent No. 5853989 Japanese Patent No. 6217588 Japanese Patent No. 4130091 Japanese Patent No. 5783128 Japanese Patent No. 5843368 Japanese Patent No. 5733087 Japanese Patent No. 4557136 Japanese Patent No. 4588285

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermally conductive silicone adhesive composition having high adhesiveness, giving a cured product having high elongation and high hardness.

As a result of diligent studies to achieve the above object, the present inventors have found that the following thermally conductive silicone adhesive composition can achieve the above object, and have completed the present invention.

That is, the present invention
1. 1. (A) Organopolysiloxane having a viscosity at 25 ° C. of 0.3 to 50 Pa · s, having at least two alkenyl groups bonded to silicon atoms in one molecule, and having no organoxisilyl group: 100. Mass part,
(B) Organopolysiloxane having a viscosity at 25 ° C. of 0.3 to 50 Pa · s and both ends sealed with a trialkoxysilyl group: 1 to 100 parts by mass,
(C) Organopolysiloxane represented by the following general formula (1): 1 to 100 parts by mass,

(In the formula, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ² is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, respectively. n is an integer of 2 to 100, and a is an integer of 1 to 3.)
(D) One or both of the organohydrogensiloxanes represented by the following general formulas (2-1) and (2-2),

(In the formula, R ³ is an alkyl group having 1 to 6 ^{carbon atoms independently, and R 4} is an epoxy group independently bonded to a silicon atom via a carbon atom or a carbon atom and an oxygen atom. i is an integer of 2 or more, j is an integer of 1 or more, and i + j is an integer of 4 to 12. In the formula (2-1), the arrangement order of the siloxane units may be arbitrary. X is It is a divalent hydrocarbon group that may contain an ether bond, and k is an independently integer of 3 to 11).
(E) Organohydrogenpolysiloxane represented by the following general formula (3),

(In the formula, R ⁵ is an alkyl group having 1 to 6 carbon atoms independently, and q is an integer of 5 to 1,000 carbon atoms.)
(F) Thermally conductive filler: 500 to 3,000 parts by mass, and (G) platinum group metal-based catalyst.
[Total number of Si—H groups] / [Total number of alkenyl groups] is 0.6 to 2.0, and [Number of Si—H groups in (D) component] / [(E) component. The number of Si—H groups] is 0.1 to 4.0, a thermally conductive silicone adhesive composition,
2. The thermally conductive silicone adhesive 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. 3. A cured product of the thermally conductive silicone adhesive composition according to 1 or 2.
4. 3. The cured product according to 3, which has an elongation at the time of cutting of 30% or more and a shear tensile adhesive strength of 0.5 MPa or more.
5. The cured product according to 3 or 4 having a type A durometer hardness of 60 or more is provided.

The thermally conductive silicone adhesive composition of the present invention provides a cured product having excellent extensibility and adhesiveness. Therefore, the present invention can follow, for example, even if the gap between the heat generating component and the cooling member is large, does not break the material, and is difficult to peel off from the interface of the base material of the component or member, and is expensive. It is possible to provide a high-hardness thermally conductive silicone adhesive composition that provides a reliable cured product.

Hereinafter, the present invention will be described in more detail.
[Thermal conductive silicone adhesive composition]
The thermally conductive silicone adhesive composition of the present invention
(A) Organopolysiloxane having at least two alkenyl groups in one molecule,
(B) Organopolysiloxane with both ends sealed with a trialkoxysilyl group,
(C) Organopolysiloxane, one end of which is sealed with an alkoxysilyl group or the like.
(D) Cyclic organohydrogensiloxane,
(E) A linear organohydrogenpolysiloxane having Si—H groups at both ends,
(F) Thermally conductive filler,
(G) Contains a platinum group metal catalyst.

[(A) component]
The component (A) is an organopolysiloxane having at least two alkenyl groups bonded to a silicon atom in one molecule and no organoxisilyl group. The component (A) is distinguished from the component (B) and the component (C) in that it does not have an organoxisilyl group.

The viscosity of the component (A) at 25 ° C. is 0.3 to 50 Pa · s, preferably 0.4 to 10 Pa · s, and more preferably 0.6 to 5 Pa · s. If the viscosity at 25 ° C. is less than 0.3 Pa · s, the elongation of the composition becomes poor, and if it exceeds 50 Pa · s, the viscosity of the composition becomes high and the workability deteriorates. In the present invention, the viscosity is a value measured by a rotational viscometer (the same applies hereinafter).

The component (A) is not particularly limited as long as it satisfies the above viscosity and alkenyl group content, and a known organopolysiloxane can be used. Examples of the molecular structure include linear, branched chain, linear with partial branch, dendrimer (dendrimer) and the like, and preferably linear and linear with partial branch. .. The component (A) may be a single polymer having these molecular structures, a copolymer having these molecular structures, or a mixture containing two or more kinds of these polymers.

Specifically, a linear diorganopolysiloxane in which the main chain basically consists of repeating diorganosiloxane units and both ends of the molecular chain are sealed with a triorganosyloxy group or a silanol-containing group is preferable. When the molecular structure of the organopolysiloxane of the component (A) is linear or branched, the position of the silicon atom to which the alkenyl group is bonded in the molecule of the organopolysiloxane is at the end of the molecular chain and in the middle of the molecular chain. Either one of (bifunctional diorganosiloxane unit located at the non-terminal of the molecular chain or trifunctional monoorganosylsesquioxane unit) may be located at both of them when there are two or more of them. Particularly preferable in terms of flexibility, it is a linear diorganopolysiloxane containing an alkenyl group bonded to silicon atoms at both ends of the molecular chain.

The alkenyl group bonded to the silicon atom preferably has 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, 1-butenyl, and 1-hexenyl groups. Among these, a vinyl group is preferable from the viewpoint of ease of synthesis and cost. The number of alkenyl groups in one molecule of the component (A) is preferably 2 to 10.

Examples of the organic group bonded to the silicon atom other than the alkenyl group include a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, excluding the aliphatic unsaturated bond. Examples of such a monovalent hydrocarbon group include an alkyl group such as methyl, ethyl, n-propyl, n-butyl, n-hexyl and n-dodecyl group, an aryl group such as a phenyl group, and a 2-phenylethyl group. , 2-Phenylpropyl group and other aralkyl groups and the like. In addition, trifluoromethyl, 2-bromoethyl, chloromethyl, 3,3,3-trifluoropropyl group, etc. in which some or all of the hydrogen atoms of these hydrocarbon groups are replaced with halogen atoms such as chlorine, fluorine and bromine. Halogen-substituted monovalent hydrocarbon groups and the like. Among these, an alkyl group having 1 to 6 carbon atoms is preferable, and 90% or more of the total number of organic groups other than the alkenyl group bonded to the silicon atom in the component (A) is taken from the viewpoint of ease of synthesis and cost. Is preferably a methyl group.

The component (A) does not contain an organoxysilyl group, and examples of the organoxy group include an alkoxy group, an alkoxyalkoxy group, an alkenyloxy group, and an asyloxy group. Examples of the alkoxy group include those having 1 to 10 carbon atoms, particularly 1 to 6, particularly 1 to 3, and examples thereof include a methoxy group and an ethoxy group. Examples of the alkoxyalkoxy group include those having 1 to 6 carbon atoms, particularly 1 to 3 carbon atoms in each alkoxy group, and examples thereof include a methoxyethoxy group and a methoxypropoxy group. Examples of the alkenyloxy group include those having 2 to 6 carbon atoms, and examples thereof include a vinyloxy group and an aryloxy group. Examples of the asyloxy group include those having 1 to 10 carbon atoms, and examples thereof include an acetyloxy group and an octanoyloxy group.

Examples of the component (A) include dimethylpolysiloxane having both ends of the molecular chain and dimethylvinylsiloxy group-blocking, methylphenylvinylsiloxy group-blocking dimethylpolysiloxane at both ends of the molecular chain, and dimethylsiloxane and methylphenyl having both-terminal dimethylvinylsiloxy group blocking. Siloxane copolymer, dimethylvinyl siloxy group-sealed dimethylsiloxane / methylvinylsiloxane copolymer at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer containing silanol groups at both ends of the molecular chain, dimethylsiloxane containing silanol groups at both ends of the molecular chain -Methylvinylsiloxane-Methylphenylsiloxane copolymer, trimethylsiloxy group-blocking dimethylsiloxane at both ends of the molecular chain dimethylsiloxane-Methylvinylsiloxane copolymer, dimethylvinylsiloxy group-blocking methyl at both ends of the molecular chain (3,3,3-trifluoropropyl) ) Polysiloxane, formula: (CH ₃ ) ₃ siloxane unit represented by SiO _1/2 and formula: (CH ₃ ) ₂ (CH ₂ = CH) siloxane unit represented by _{SiO 1/2} _{and formula: CH 3} _Examples include an organopolysiloxane copolymer composed of a siloxane unit represented by SiO 3/2 and a formula: (CH ₃ ) ₂ a siloxane unit represented by SiO _2/2 , and dimethylvinylsiloxy groups at both ends of the molecular chain. Sealed dimethylpolysiloxane is particularly preferred.

[Component (B)]
The component (B) is an organopolysiloxane having both ends sealed with a trialkoxysilyl group, and has a role of lowering the viscosity of the composition and enabling high filling of the thermally conductive filler. The component (B) is distinguished from the component (A) in that it has an alkoxy group at both ends.

The viscosity of the component (B) at 25 ° C. is 0.3 to 50 Pa · s, preferably 0.4 to 10 Pa · s, and more preferably 0.5 to 5 Pa · s. When the viscosity at 25 ° C. is less than 0.3 Pa · s, it causes oil bleeding and the adhesiveness deteriorates, and when it exceeds 50 Pa · s, the composition becomes highly viscous and the workability deteriorates.

Each alkoxy group forming a trialkoxysilyl group at both ends is preferably independently having 1 to 6 carbon atoms, particularly 1 to 4, and examples of the trialkoxysilyl group include a trimethoxysilyl group and a triethoxysilyl group. Can be mentioned.

The component (B) is not particularly limited except for the structure at both ends, and the substituents bonded to the silicon atom other than both ends include methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl. An alkyl group such as a group, a cycloalkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group or an allyl group, a monovalent hydrocarbon group having 1 to 8 carbon atoms such as an aryl group such as a phenyl group or a trill group, or one of these. Examples thereof include a chloromethyl group in which a part or all of the hydrogen atoms of the valent hydrocarbon group are replaced with halogen atoms such as chlorine, fluorine and bromine, and a halogenated hydrocarbon group such as a trifluoromethyl group.

Specifically, the component (B) is preferably an organopolysiloxane represented by the following formula (4).

In the formula (4), R ⁶ is an alkyl group having 1 to 6 carbon atoms independently, and specific examples thereof include methyl, ethyl, n-propyl, and n-butyl groups. As R ⁶ , an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group and an ethyl group are more preferable. R ⁷ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, respectively, and specifically, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and so on. Alkyl groups such as n-heptyl groups, aryl groups such as phenyl groups and tolyl groups, and chloromethyl, 3-, in which some or all of the hydrogen atoms of these groups are replaced with halogen atoms such as chlorine, fluorine and bromine. Examples thereof include halogenated hydrocarbon groups such as chloropropyl and trifluoromethyl groups. As R ⁷ , an alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group and an ethyl group are particularly preferable. r is an integer such that the viscosity of the organopolysiloxane represented by the formula (4) at 25 ° C. is 0.3 to 50 Pa · s.

The blending amount of the component (B) is 1 to 100 parts by mass, preferably 1 to 50 parts by mass, more preferably 1 to 10 parts by mass, and particularly preferably 6 to 6 to 100 parts by mass with respect to 100 parts by mass of the component (A). It is 10 parts by mass. If it is less than 1 part by mass, the viscosity of the composition becomes high, and if it exceeds 100 parts by mass, the adhesiveness deteriorates. The component (B) may be used alone or in combination of two or more.

[Component (C)]
The component (C) is an organopolysiloxane represented by the following general formula (1).

In formula (1), R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10, preferably 1 to 6, and more preferably 1 to 3, respectively having 1 to 10 carbon atoms, and for example, alkyl, alkenyl, and so on. Aryl, aralkyl, alkyl halides, cyanoalkyl groups and the like can be mentioned. The alkyl group may be linear, branched or cyclic. Examples of the linear alkyl group include methyl, ethyl, n-propyl, n-hexyl, n-octyl group and the like. Examples of the branched chain alkyl group include isopropyl, isobutyl, tert-butyl, 2-ethylhexyl group and the like. Examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the alkenyl group include vinyl, allyl, 1-butenyl, 1-hexenyl group and the like. Examples of the aryl group include a phenyl group and a tolyl group. Examples of the aralkyl group include a 2-phenylethyl group and a 2-methyl-2-phenylethyl group. Examples of the alkyl halide group include 3,3,3-trifluoropropyl, 2- (nonafluorobutyl) ethyl, 2- (heptadecafluorooctyl) ethyl group and the like. Examples of the cyanoalkyl group include a cyanoethyl group and the like. Among these, ^{as R 1} , a methyl group, a phenyl group, and a vinyl group are preferable.

R ² is an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, respectively. As the alkyl group, for example, ^{like the one exemplified in R 1} , linear, branched or cyclic carbon atoms 1 to 10, preferably 1 to 6, more preferably 1 to 3 unsubstituted or substituted. Alkyl group of, and specific examples thereof include the same. Examples of the alkoxyalkyl group include those having an alkoxy group and an alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, and examples thereof include a methoxyethyl group and a methoxypropyl group. Examples of the alkenyl group include those having 2 to 6 carbon atoms, and examples thereof include a vinyl group and an allyl group. Examples of the acyl group include those having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and examples thereof 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.

n is an integer of 2 to 100, preferably an integer of 5 to 80. If n is less than 2, oil bleeding is likely to occur from the composition, and the adhesive strength decreases with time. If n exceeds 100, the viscosity of the composition becomes high and the workability becomes poor.
a is an integer of 1 to 3, preferably 3.

The viscosity of the component (C) at 25 ° C. is preferably 0.005 to 10 Pa · s, and particularly preferably 0.005 to 1 Pa · s. Within such a range, oil bleeding of the cured product can be suppressed, and the handleability of the adhesive composition is excellent.

As a suitable specific example of the component (C), an organopolysiloxane represented by the following average formula can be mentioned.

The blending amount of the component (C) is 1 to 100 parts by mass, preferably 5 to 50 parts by mass, and more preferably 12 to 50 parts by mass with respect to 100 parts by mass of the component (A). If it is less than 1 part by mass, a low-viscosity composition cannot be obtained, and if it exceeds 100 parts by mass, the adhesiveness of the composition deteriorates. The component (C) may be used alone or in combination of two or more.

[Component (D)]
The component (D) is either or both of the organohydrogensiloxanes represented by the following general formulas (2-1) and (2-2), and has a role of exhibiting high adhesiveness.

R ³ is an alkyl group having 1 to 6 carbon atoms independently, and examples thereof include methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl groups. Among these, those having 1 to 3 carbon atoms are preferable, and 90 mol% or more of the total number of ^{R 3 is more preferably a methyl group from the viewpoint of ease of synthesis and cost.}

R ⁴ is an epoxy group that is independently bonded to a silicon atom via a carbon atom or a carbon atom and an oxygen atom. Examples of such a group include an epoxy group-containing organic group such as 3-glycidoxypropyl, 3-glycidoxyethyl, and 3,4-epoxycyclohexylethyl group.

i is an integer of 2 or more, j is an integer of 1 or more, i + j is an integer of 4 to 12, preferably an integer of 4 to 8, more preferably an integer of 4 to 6, and further. It is preferably 4.

In the formula (2-2), X is a divalent hydrocarbon group which may contain an ether bond, and is preferably a group containing a bisphenol A residue represented by the following formula (5).

(The broken line represents the bond with the silicon atom.)

k is independently an integer of 3 to 11, preferably an integer of 3 to 7, more preferably an integer of 3 to 5, and even more preferably 3.
The sequence order of the siloxane units in the formula (2-1) may be arbitrary, and may be random, block, or alternate.

As a preferable specific example of the component (D), an organohydrogensiloxane represented by the following structural formula can be mentioned. The component (D) may be used alone or in combination of two or more.

[(E) component]
The component (E) is an organohydrogenpolysiloxane represented by the following general formula (3), and plays a role of improving the elongation of the composition after curing while having high adhesiveness.

R ⁵ is an alkyl group having 1 to 6 carbon atoms independently, and examples thereof include methyl, ethyl, n-propyl, n-butyl, and n-hexyl groups. Among these, those having 1 to 3 carbon atoms are preferable, and 90% or more of the total number of ^{R 5 is more preferably a methyl group from the viewpoint of ease of synthesis and cost.}
q is an integer of 5 to 1,000, preferably an integer of 10 to 100. When q is less than 5, it is difficult to use it for electronic parts because organohydrogenpolysiloxane tends to be a volatile component, and when q value exceeds 1,000, the viscosity of organohydrogenpolysiloxane is high. It becomes difficult to handle.

Specific examples of the component (E) include organohydrogenpolysiloxane represented by the following average formula. The component (E) may be used alone or in combination of two or more.

The blending amount of the components (D) and (E) is based on the total number of alkenyl groups in the components (A) and, in some cases, the components (B) and (C), and the amount of Si in the components (D) and (E). The ratio of the total number of H groups, that is, the [total number of Si—H groups] / [total number of alkenyl groups] is 0.6 to 2.0, preferably 0.7 to 1.5. Is the amount that becomes. If the above ratio is less than 0.6, the cured product cannot form a sufficient crosslinked structure, and mechanical properties and adhesiveness cannot be obtained. If it exceeds 2.0, the elongation decreases.

Further, as for the blending ratio of the component (D) and the component (E), [the number of Si—H groups in the component (D)] / [the number of Si—H groups in the component (E)] is 0.1. It is in the range of about 4.0, preferably 0.2 to 3.0. If the blending ratio is less than 0.1, the adhesiveness is low, and if it exceeds 4.0, the elongation of the cured product is lowered.

[(F) component]
The component (F) is a heat conductive filler and has a role of imparting heat conductivity to the composition (cured product). Examples of the heat conductive filler 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, and diamond powder. , Carbon powder, indium, gallium and the like.
The component (F) may be used alone or in combination of two or more.

The average particle size of the thermally conductive filler is preferably 0.1 to 100 μm, more preferably 0.5 to 90 μm from the viewpoint of filling property and uniformity. The shape of the thermally conductive filler may be irregular, spherical, or any shape. The average particle size can be determined as the volume average value D ₅₀ (that is, the particle size or the median diameter when the cumulative volume becomes 50%) in the particle size distribution measurement by the laser light diffraction method.

The thermally conductive filler preferably has a thermal conductivity (25 ° C.) of 10 W / m · K or more. With such a heat conductive filler, sufficient heat conductivity can be imparted to the cured product. The thermal conductivity is a value based on JIS R 1611: 2010.

The blending amount of the component (F) is 500 to 3,000 parts by mass, preferably 1,000 to 2,000 parts by mass with respect to 100 parts by mass of the component (A). If the blending amount of the component (F) is less than 500 parts by mass, the desired thermal conductivity cannot be imparted to the cured product, and if it exceeds 3,000 parts by mass, the composition does not become liquid and is handled. Inferior in sex.

[(G) component]
The component (G) is a platinum group metal-based catalyst. The platinum group metal-based catalyst causes an addition reaction between the alkenyl group in the component (A) and, in some cases, the components (B) and (C) and the Si—H group in the components (D) and (E). Any catalyst may be used as long as it promotes it, and among them, a catalyst selected from platinum and a platinum compound is preferable.

Examples of such a catalyst include platinum (including platinum black), rhodium, palladium and other platinum group metals alone, H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaHP _{PtCl 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 (However, in the formula N is an integer of 0 to 6, preferably 0 or 6), such as platinum chloride, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid, complex of chloroplatinic acid and olefin, platinum. Platinum group metals such as black and palladium supported on carriers such as alumina, silica and carbon, rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkinson catalyst), platinum chloride, platinum chloride acid or chloride. Examples thereof include a complex of chloroplatinate and a vinyl group-containing siloxane. These platinum group metal-based catalysts may be used alone or in combination of two or more.

The blending amount of the component (G) may be an effective amount as a catalyst, and may be appropriately adjusted according to a desired curing rate. From the viewpoint of curing speed and cost, the total mass of the components (A) to (F) is preferably 0.1 to 10,000 ppm, more preferably 10,000 to 10,000 ppm based on the mass converted to platinum group metal atoms. Is.

[(H) component]
A reaction control agent may be added as the component (H) to the thermally conductive silicone adhesive composition of the present invention in order to suppress the progress of the curing reaction at room temperature and prolong the shelf life and pot life. .. The reaction control agent may be any as long as it can suppress the catalytic activity of the component (G), for example, an acetylene compound such as 1-ethynyl-1-cyclohexanol and 3-butin-1-ol, and triallyl. Examples thereof include nitrogen-containing compounds such as isocyanurate and triallyl isocyanurate derivatives, organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds. Among these, acetylene alcohol, which is not corrosive to metals, is preferable. These may be diluted with an organic solvent such as toluene, xylene, or isopropyl alcohol in order to improve the dispersibility in the composition.
The component (H) may be used alone or in combination of two or more.

When the component (H) is used, the blending amount is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the component (A), more preferably, from the viewpoint of achieving both storage stability and curability of the composition. Is 0.05 to 1 part by mass.

[Other ingredients]
In addition to the above components (A) to (H), known additives may be added to the heat conductive silicone adhesive composition of the present invention as long as the object of the present invention is not impaired. Examples of such additives include hindered phenolic antioxidants, reinforcing and non-reinforcing fillers such as calcium carbonate, and polyethers as thixotropy improvers. Further, if necessary, a colorant such as a pigment or a dye may be added.

[Manufacturing method of thermally conductive silicone adhesive composition]
The thermally conductive silicone adhesive composition of the present invention is known to contain components (A) to (G), components (H) as required, and other components using a gate mixer, a kneader, a planetary mixer, or the like. It can be prepared by mixing by the method.
The thermally conductive silicone adhesive of the present invention comprises a first agent composed of (A), (B), (C), (F), (G) components, and if necessary, other components, and (A). , (B), (C), (D), (E), (F) components and, if necessary, other components are prepared separately, and the first agent and the second agent are prepared before use. May be used as a two-part composition in which the above is mixed. In addition, there may be a component commonly used in the first agent and the second agent. By using such a two-dosage form for the composition, storage stability can be further ensured.

The viscosity of the thermally conductive silicone adhesive composition of the present invention at 25 ° C. is preferably 50 to 400 Pa · s, more preferably 100 to 300 Pa · s, from the viewpoint of dispersibility and workability of the thermally conductive filler. s.

The curing conditions of the heat conductive silicone adhesive composition of the present invention are not particularly limited, and can be the same conditions as those of conventionally known silicone gels. Further, the thermally conductive silicone adhesive composition of the present invention can be cured by heat from a heat-generating component after coating, but it may be positively cured by heating. The heat curing conditions are preferably 60 to 150 ° C., more preferably 80 to 120 ° C., preferably 0.1 to 3 hours, more preferably 0.5 to 2 hours.

The mechanical properties of the cured product of the thermally conductive silicone adhesive composition of the present invention are that the elongation at cutting specified in JIS K 6251: 2017 is 30% or more, and the shear tensile adhesive strength specified in JIS K 6850: 1999. Is preferably 0.5 MPa or more. If it has such mechanical characteristics, it can follow the gap between the heat generating component and the cooling component without breaking even by temperature stress, and the reliability of the entire component can be dramatically improved.

Further, the cured product of the heat conductive silicone adhesive composition of the present invention preferably has a hardness of 60 or more as measured by a type A durometer specified in JIS K6253-3: 2012. If it exhibits such hardness, curing has proceeded sufficiently, and it is possible to exhibit high adhesiveness.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Each component used in Examples and Comparative Examples is shown below. The viscosity of each component is a value measured by a rotational viscometer.

First, the following components were prepared.
Component (A) A-1: Both ends are sealed with a dimethylvinylsilyl group, and dimethylpolysiloxane having a viscosity at 25 ° C. of 0.6 Pa · s. A-2: Both ends are sealed with a dimethylvinylsilyl group. Didimethylpolysiloxane with a viscosity of 1.0 Pa · s at 25 ° C. A-3: Didimethylpolysiloxane with both ends sealed with a dimethylvinylsilyl group and a viscosity at 25 ° C. of 5.0 Pa · s.

Component (B) -B-1: Dimethylpolysiloxane having both ends sealed with a trimethoxysilyl group and a viscosity of 1.0 Pa · s at 25 ° C.

Component (C) C-1: Organopolysiloxane represented by the following general formula (viscosity at 25 ° C.: 35 mPa · s)

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

-D-2: Organohydrogensiloxane represented by the following structural formula

-D-3: Organohydrogensiloxane represented by the following structural formula

-D-4 (comparative component): Organohydrogensiloxane represented by the following structural formula

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

-E-2 (Comparative component): Organohydrogenpolysiloxane represented by the following average structural formula

(F) Ingredients The thermally conductive fillers shown in (i) to (iv) below are mixed so as to have the composition shown in Table 1 below, and a 5L gate mixer (trade name: 5L planetary mixer, Inoue Seisakusho Co., Ltd.) F-1 and F-2 were obtained by mixing at room temperature for 30 minutes.
(I) Alumina powder with an average particle size of 80 μm: thermal conductivity 36 W / m · K
(Ii) Alumina powder with an average particle size of 40 μm: thermal conductivity 36 W / m · K
(Iii) Alumina powder with an average particle size of 10 μm: thermal conductivity 36 W / m · K
(Iv) Alumina powder with an average particle size of 1.0 μm: thermal conductivity 36 W / m · K

Component (G) G-1: Didimethylpolysiloxane solution of platinum-divinyltetramethyldisiloxane complex (dissolved in the same dimethylpolysiloxane as A-1 above. Platinum content: 1% by mass)

Ingredient (H) ・ H-1: 1-ethynyl-1-cyclohexanol ・ H-2: Triallyl isocyanurate

[Preparation of thermally conductive silicone adhesive composition]
Ingredients (A), (B), and (C) are added to a 5L gate mixer (trade name: 5L planetary mixer, manufactured by Inoue Seisakusho Co., Ltd.), and the component (F) is added in the blending amount shown in Table 2, and 150 Mix at ° C. for 2 hours. Next, the component (H) was added in the blending amounts shown in Table 2 and mixed at 25 ° C. for 30 minutes. Then, the component (G) was further added in the blending amount shown in Table 2, and mixed at 25 ° C. for 30 minutes. Finally, the components (D) and (E) were added in the blending amounts shown in Table 2 and mixed at 25 ° C. for 30 minutes. The physical characteristics of each of the obtained compositions were measured by the methods shown below. The results are also shown in Table 2.

〔viscosity〕
The viscosity of the thermally conductive silicone adhesive composition at 25 ° C. was measured at a rotation speed of 10 rpm using a PC-10AA viscometer (manufactured by Malcolm Co., Ltd.).

〔hardness〕
The thermally conductive silicone adhesive composition was press-cured at 110 ° C. for 10 minutes. Three obtained silicone sheets having a thickness of 2.0 mm were stacked, and the hardness was measured by a type A durometer specified in JIS K 6253-3: 2012.

[Tensile strength, elongation at cutting]
The thermally conductive silicone adhesive composition was press-cured at 110 ° C. for 10 minutes. The tensile strength and elongation at cutting of the obtained silicone sheet having a thickness of 2.0 mm were measured according to JIS K 6251: 2017.

[Shear tensile adhesive strength]
A heat conductive silicone adhesive composition is placed between a pair of 1.0 mm thick aluminum (JIS H 4000 A1050P) plates and a pair of 2.0 mm thick PBT (Duranex 3300, manufactured by Polyplastics Co., Ltd.) plates. The composition was heated at 110 ° C. for 10 minutes in a state of being sandwiched so as to have a thickness of 2.0 mm and an adhesive area of 25 mm × 10 mm, and the composition was cured to prepare an adhesive test piece. The shear tensile adhesive strength of the obtained test piece was measured according to JIS K 6850: 1999.

〔Thermal conductivity〕
The thermally conductive silicone adhesive composition was press-cured at 110 ° C. for 10 minutes. The thermal conductivity of the obtained cured product was measured at an ambient temperature of 25 ° C. using a hot disk method thermophysical characteristic measuring device TPA-501 (manufactured by Kyoto Electronics Industry Co., Ltd.) in accordance with ISO 22007-2.

Claims

(A) Organopolysiloxane having a viscosity at 25 ° C. of 0.3 to 50 Pa · s, having at least two alkenyl groups bonded to silicon atoms in one molecule, and having no organoxisilyl group: 100. Mass part,
(B) Organopolysiloxane having a viscosity at 25 ° C. of 0.3 to 50 Pa · s and both ends sealed with a trialkoxysilyl group: 1 to 100 parts by mass,
(C) Organopolysiloxane represented by the following general formula (1): 1 to 100 parts by mass,

(In the formula, R 1 is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R 2 is independently an alkyl group, an alkoxyalkyl group, an alkenyl group or an acyl group, respectively. n is an integer of 2 to 100, and a is an integer of 1 to 3.)
(D) One or both of the organohydrogensiloxanes represented by the following general formulas (2-1) and (2-2),

(In the formula, R 3 is an alkyl group having 1 to 6 carbon atoms independently, and R 4 is an epoxy group independently bonded to a silicon atom via a carbon atom or a carbon atom and an oxygen atom. i is an integer of 2 or more, j is an integer of 1 or more, and i + j is an integer of 4 to 12. In the formula (2-1), the arrangement order of the siloxane units may be arbitrary. X is It is a divalent hydrocarbon group that may contain an ether bond, and k is an independently integer of 3 to 11).
(E) Organohydrogenpolysiloxane represented by the following general formula (3),

(In the formula, R 5 is an alkyl group having 1 to 6 carbon atoms independently, and q is an integer of 5 to 1,000 carbon atoms.)
(F) Thermally conductive filler: 500 to 3,000 parts by mass, and (G) platinum group metal-based catalyst.
[Total number of Si—H groups] / [Total number of alkenyl groups] is 0.6 to 2.0, and [Number of Si—H groups in (D) component] / [(E) component. A thermally conductive silicone adhesive composition having a [number of Si—H groups] of 0.1 to 4.0.
The thermally conductive silicone adhesive composition according to claim 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).
A cured product of the thermally conductive silicone adhesive composition according to claim 1 or 2.
The cured product according to claim 3, which has an elongation at the time of cutting of 30% or more and a shear tensile adhesive strength of 0.5 MPa or more.
The cured product according to claim 3 or 4, which has a type A durometer hardness of 60 or more.