WO2018207696A1

WO2018207696A1 - Thermally conductive silicone composition

Info

Publication number: WO2018207696A1
Application number: PCT/JP2018/017490
Authority: WO
Inventors: 山田　邦弘
Original assignee: 信越化学工業株式会社
Priority date: 2017-05-09
Filing date: 2018-05-02
Publication date: 2018-11-15
Also published as: TW201903117A; JP6705426B2; JP2018188559A

Abstract

Provided is a thermally conductive silicone composition which contains: (A) a silicone gel crosslinked product; (B) a silicone oil which is a surface treatment agent of component (C) below and does not contain each of an aliphatic unsaturated bond and a SiH group; and (C) a thermally conductive filler, wherein the loss factor Tanδ at a frequency of 0.2 Hz at 25°C is 2.0 or less as measured by a viscoelasticity measuring device. This composition has fluidity and markedly improved shift resistance.

Description

Thermally conductive silicone composition

The present invention relates to a thermally conductive silicone composition having excellent misalignment resistance.

Generally, since heat is generated during use of electric / electronic parts, heat removal is necessary for proper operation of the electric parts, and various heat conductive materials for heat removal have been proposed. This heat conductive material is roughly classified into two types: 1) a sheet-like material that is easy to handle, and 2) a paste-like material.

The sheet-like material is easy to handle and has the advantage of being excellent in stability, but since the contact thermal resistance increases in nature, the heat dissipation performance is inferior to the paste-like material. In addition, a certain degree of strength / hardness is required to maintain the sheet shape, the tolerance generated between the electric / electronic component element and the heat radiating member cannot be absorbed, and the element may be destroyed by the stress.

On the other hand, the paste-like material can be applied to mass production by using a coating device or the like, and the heat dissipation performance is excellent because the contact thermal resistance is low. However, when mass-produced by screen printing or the like, the viscosity of the paste should be low, but in that case, the paste will shift due to the thermal shock of the element (pump-out phenomenon), and heat removal cannot be sufficiently performed. As a result, the device sometimes malfunctions. In addition, the following silicone compositions and the like have been proposed as past techniques, but there has been a demand for a thermally conductive silicone composition that provides more sufficient performance and is excellent in misalignment resistance.

Japanese Patent No. 3948642 Japanese Patent No. 3195277 JP 2000-169873 A JP 2006-143978 A JP 2004-210856 A JP 2005-162975 A Japanese Patent No. 5300408 Japanese Patent No. 4796704 Japanese Patent No. 3541390 Japanese Patent No. 4130091 Japanese Patent No. 5388329

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 composition having excellent misalignment resistance.

As a result of intensive investigations to achieve the above object, the present inventor has found that a silicone gel cross-linked product, a specific silicone oil, particularly a one-end hydrolyzable organopolysiloxane, and a thermally conductive filler are included, and at a specific frequency. The present inventors have found that a composition exhibiting a specific loss coefficient Tanδ value has drastic improvement in misalignment resistance while having fluidity, and has led to the present invention.

Accordingly, the present invention provides the following thermally conductive silicone composition.
[1]
(A) a silicone gel crosslinked product,
(B) Silicone oil that does not contain an aliphatic unsaturated bond and SiH group, and serves as a surface treatment agent for the following component (C):
(C) A thermally conductive silicone composition comprising a thermally conductive filler and having a loss coefficient Tanδ at a frequency of 0.2 hertz at 25 ° C. measured by a viscoelasticity measuring device is 2.0 or less.
[2]
(A) Silicone gel crosslinked product: 100 parts by mass,
(B) Silicone oil comprising a one-end hydrolyzable organopolysiloxane represented by the following general formula (1): 201 to 500 parts by mass,

Wherein R ¹ is independently an alkyl group having 1 to 6 carbon atoms, and R ² is each independently an unsubstituted or substituted monovalent group having no aliphatic unsaturated bond having 1 to 18 carbon atoms. One or more groups selected from the group of hydrocarbon groups, a is an integer of 5 to 120)
(C) Thermally conductive filler having an average particle size of 0.1 to 150 μm: The thermally conductive silicone composition according to [1], comprising 2,001 to 10,000 parts by mass.
[3]
The heat conductive silicone composition according to [1] or [2], wherein the component (A) is a crosslinked silicone gel of the following component (D) and component (E).
(D) The following average composition formula (2)
R ³ _b R ⁴ _c SiO _{(4-bc) / 2} (2)
(Wherein R ³ represents an alkenyl group, R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and b is a number of 0.0001 to 0.2. And c is a number from 1.7 to 2.2, where b + c is a number satisfying 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom represented by
(E) At least 4 hydrogen atoms bonded to a silicon atom at the non-terminal end of the molecular chain are contained in one molecule, and the following formula (3)
0.1 <α / β (3)
(In the formula, α represents the number of hydrogen atoms bonded to non-terminal silicon atoms of the molecular chain, and β represents the total number of silicon atoms in the component (E).)
Organohydrogenpolysiloxane satisfying the following: 0.3 to 2.0 hydrogen atoms bonded to silicon atoms in component (E) for one alkenyl group bonded to silicon atoms in component (D) Amount to be.
[4]
Furthermore, (G) a non-functional liquid silicone oil having a kinematic viscosity at 25 ° C. of 10 to 500,000 mm ² / s is contained in an amount of 10 to 500 parts by weight per 100 parts by weight of component (A) [1] to [3] The thermally conductive silicone composition according to any one of [3].
[5]
The heat conductive silicone composition according to any one of [1] to [4], wherein the viscosity at 25 ° C. is 100 to 1,500 Pa · s.

The heat conductive silicone composition of the present invention has a fluidity, but a significant improvement in misalignment resistance is recognized.

Hereinafter, the present invention will be described in detail.
In the thermally conductive silicone composition of the present invention, the deviation resistance correlates with the loss coefficient Tanδ value, and if the loss coefficient Tanδ at a frequency of 0.2 Hertz at 25 ° C. by a viscoelasticity measuring device is greater than 2.0, Sexuality gets worse. Accordingly, Tan δ is preferably 2.0 or less, preferably 1.8 or less, and more preferably 1.6 or less. In this case, the lower limit value of Tan δ is not particularly limited, but is usually 0.8 or more, particularly 1.0 or more. For convenience, Tanδ at 0.2 Hz is specified. However, since each Tanδ does not change significantly in the range of 0.1 to 0.5 Hz, the Tanδ value at any frequency is specified within that range. There is no problem.

Here, Tan δ is a value measured by a viscoelasticity measuring device, and in the case of the present invention, a viscoelasticity measuring device (model name: HAAKE MAS) manufactured by Thermo Fisher Scientific Co. is used, and a strain amount is 0.5%. Using a circular parallel plate with a diameter of 20 mm, the loss coefficient Tanδ at each frequency was measured at a temperature of 25 ° C. and a material thickness of 1 mm, and Tanδ at a frequency of 0.2 Hertz was used as a value.

In the present invention, the thermally conductive silicone composition for obtaining the loss factor Tanδ is as follows:
(A) a silicone gel crosslinked product,
(B) Silicone oil that does not contain an aliphatic unsaturated bond and SiH group, and serves as a surface treatment agent for the following component (C):
(C) A heat conductive filler is contained.

Hereinafter, these components will be described in detail.
[Component (A)]
The silicone gel crosslinked product is used as a matrix of the thermally conductive silicone composition of the present invention. Component (A) is obtained by subjecting the following components (D) and (E) to a hydrosilylation reaction (addition reaction) in the presence of component (F).
(D) The following average composition formula (2)
R ³ _b R ⁴ _c SiO _{(4-bc) / 2} (2)
(Wherein R ³ represents an alkenyl group, R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and b is a number of 0.0001 to 0.2. And c is a number from 1.7 to 2.2, where b + c is a number satisfying 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom represented by
(E) At least 4 hydrogen atoms bonded to a silicon atom at the non-terminal end of the molecular chain are contained in one molecule, and the following formula (3)
0.1 <α / β (3)
(In the formula, α represents the number of hydrogen atoms bonded to non-terminal silicon atoms of the molecular chain, and β represents the total number of silicon atoms in the component (E).)
Organohydrogenpolysiloxane satisfying the following: 0.3 to 2.0 hydrogen atoms bonded to silicon atoms in component (E) for one alkenyl group bonded to silicon atoms in component (D) The amount of
(F) Platinum-based catalyst: effective amount.

[(D) component]
(D) A component is a component used as the main ingredient of a component (A). The component (D) is an organopolysiloxane having at least one alkenyl group bonded to a silicon atom (hereinafter referred to as “silicon atom-bonded alkenyl group”) in one molecule represented by the above average composition formula (2). . The alkenyl group preferably has at least two, more preferably 2 to 50, and particularly preferably 2 to 20 in one molecule. These alkenyl groups may be bonded to the silicon atom at the end of the molecular chain, bonded to the silicon atom at the non-terminal end of the molecular chain (that is, other than both ends of the molecular chain), or a combination thereof. Good.

In the above formula (2), R ³ usually represents an alkenyl group having 2 to 6, preferably 2 to 4 carbon atoms. Specific examples thereof include lower alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group and isobutenyl group, with vinyl group being preferred. R ⁴ usually represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12, preferably 1 to 10, more preferably 1 to 6 carbon atoms and not having an aliphatic unsaturated bond. Specific examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclohexyl, octyl, decyl, dodecyl and the like. An aryl group such as a phenyl group or a tolyl group; an aralkyl group such as a benzyl group or a phenylethyl group; a chloromethyl group in which some or all of the hydrogen atoms of these groups are substituted with a halogen atom such as fluorine or chlorine; 3,3,3-trifluoropropyl group and the like can be mentioned, and from the viewpoint of ease of synthesis, a methyl group, a phenyl group, and a 3,3,3-trifluoropropyl group are preferable.

In the above formula (2), the values of b, c and b + c are as described above, but b is preferably a number from 0.0005 to 0.1, and c is a number from 1.9 to 2.0. And b + c is preferably a number satisfying 1.95 to 2.05.

The molecular structure of the organopolysiloxane of this component is not particularly limited, but is linear; R ³ SiO _3/2 units, R ⁴ SiO _3/2 units, SiO ₂ units (in the formula, R ^The groups represented by ³ and R ⁴ are as defined above.) Any of branched, cyclic, three-dimensional network (resinous) and the like, but the main chain is usually basically It is a linear diorganopolysiloxane composed of repeating diorganosiloxane units and having both ends of the molecular chain blocked with triorganosiloxy groups.

The kinematic viscosity of the organopolysiloxane of this component is preferably 50 to 100,000 mm ² / s at 25 ° C., more preferably 100 to 10,000 mm ² / s, still more preferably 100 to 1,000 mm ² / s. It is. When the kinematic viscosity is 50 to 100,000 mm ² / s, the obtained cured product is excellent in fluidity and workability. In addition, this kinematic viscosity is a value at 25 ° C. by an Ostwald viscometer (hereinafter the same).

Examples of the organopolysiloxane of this component that satisfies the above requirements include, for example, the following general formula (4):

(In the formula, each R ⁵ independently represents an unsubstituted or substituted monovalent hydrocarbon group, provided that at least one, preferably two or more of R ⁵ are alkenyl groups, and d is from 20 to 2, An integer of 000.)
The thing represented by is mentioned. In this formula (4), the unsubstituted or substituted monovalent hydrocarbon group represented by R ⁵ is the above R ³ (alkenyl group) and R ⁴ (unsubstituted or substituted 1 having no aliphatic unsaturated bond). The number of carbon atoms, specific examples, and the like are the same. Further, d is preferably an integer of 40 to 1,200, more preferably 50 to 600.

Specific examples of the organopolysiloxane represented by the above formula (4) include molecular chain both ends dimethylvinylsiloxy group-capped dimethylpolysiloxane, molecular chain one-end trimethylsiloxy group and one-end dimethylvinylsiloxy group-capped dimethylpolysiloxane, Molecular chain both ends trimethylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, molecular chain one-end trimethylsiloxy group / one-end dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, both ends dimethylvinylsiloxy Examples thereof include a group-capped dimethylsiloxane / methylvinylsiloxane copolymer, a molecular chain both-end dimethylvinylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer, and the like.
The organopolysiloxane of this component may be used alone or in combination of two or more.

[(E) component]
The component (E) reacts with the component (D) to act as a crosslinking agent. The component (E) has sufficient resistance to hydrogen atoms bonded to silicon atoms at the non-terminal end of the molecular chain (that is, SiH groups, hereinafter referred to as “silicon atom-bonded hydrogen atoms”) of 3 or less in one molecule. It is necessary to have at least four, because the misalignment cannot be exhibited. And the following formula (3)
0.1 <α / β (3)
(In the formula, α represents the number of hydrogen atoms bonded to non-terminal silicon atoms of the molecular chain, and β represents the total number of silicon atoms in the component (E).)
An organohydrogenpolysiloxane satisfying the above requirements. When the range of α / β is as small as 0.1 or less, the composition has poor misalignment resistance. Therefore, it is also necessary that 0.1 <α / β. In this case, α / β is preferably 0.11 or more, particularly 0.12 or more, and the upper limit is not particularly limited, but it is 0.95 or less, particularly 0.90 or less, especially 0.5 or less. preferable.

The molecular structure of this component is not particularly limited as long as it satisfies the above requirements, and may be any conventionally known, for example, linear, cyclic, branched, or three-dimensional network (resinous). . Among them, from the viewpoint of handling workability and resistance to misalignment of the cured product obtained by crosslinking the component (D), the number of silicon atoms (or polymerization degree) in one molecule is usually 3 to 1,000. The number is preferably 5 to 400, more preferably 10 to 300, still more preferably 10 to 100, and particularly preferably 10 to 60.

The kinematic viscosity of the organohydrogenpolysiloxane of this component is usually 1 to 10,000 mm ² / s, preferably 3 to 5,000 mm ² / s, more preferably 5 to 3,000 mm ² / s, still more preferably. It is preferably 10 to 1,000 mm ² / s and liquid at room temperature (25 ° C.).

As the organohydrogenpolysiloxane satisfying the above requirements, for example, those represented by the following average composition formula (5) are preferable.
R ⁶ _e H _f SiO _{(4-ef) / 2} (5)
Wherein R ⁶ represents an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, e is a number from 0.7 to 2.2, and f is from 0.001 to 0 .5, where e + f is a number satisfying 0.8 to 2.5.)

In the above formula (5), R ⁶ is usually an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and having no aliphatic unsaturated bond. Specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group. An alkyl group such as phenyl group, tolyl group, xylyl group, naphthyl group, etc .; aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group; some or all of hydrogen atoms of these groups are fluorine And a 3,3,3-trifluoropropyl group substituted with a halogen atom such as chlorine, preferably an alkyl group, an aryl group, or a 3,3,3-trifluoropropyl group, more preferably methyl Group, phenyl group and 3,3,3-trifluoropropyl group.

In the above formula (5), e, f and e + f are as described above, and e is preferably a number from 0.9 to 2.1, and f is a number from 0.002 to 0.2. The number is preferably 0.005 to 0.1, and e + f is preferably a number satisfying 1.0 to 2.3, particularly 1.5 to 2.2.

The molecular structure of the organohydrogenpolysiloxane represented by the above formula (5) is not particularly limited, and may be any of linear, cyclic, branched, three-dimensional network (resin), and the like. Among them, the number of silicon atoms in one molecule and the kinematic viscosity satisfy the above-mentioned ranges, and in particular, a linear one is preferable.

Specific examples of the organohydrogenpolysiloxane represented by the above formula (5) include molecular chain both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both ends dimethylhydrogensiloxy group. Blocked methylhydrogensiloxane / dimethylsiloxane / diphenylsiloxane copolymer, molecular chain single-ended dimethylhydrogensiloxy group / single terminal trimethylsiloxy group blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain single-ended dimethylhydrogensiloxy group, one terminal blocked with trimethylsiloxy groups methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymers, (CH ₃₎ ₂ HSiO _1/2 units and (CH ₃₎ ₃ and SiO _1/2 units ( H ₃₎ HSiO _2/2 consisting of units and SiO _4/2 units, and copolymers thereof, (CH ₃₎ ₂ HSiO _1/2 units and (CH ₃₎ ₃ SiO _1/2 units and (CH ₃₎ HSiO _{2 / A} copolymer comprising ₂ units, (CH ₃ ) ₂ SiO _2/2 units and SiO _4/2 units, (CH ₃ ) ₂ HSiO _1/2 units, (CH ₃ ) HSiO _2/2 units and (CH ₃ ) A copolymer comprising ₂ SiO _2/2 units and SiO _4/2 units, (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units, (CH ₃ ) HSiO _2/2 units and (CH ₃ ) A copolymer comprising ₂ SiO _2/2 units and (C ₆ H ₅ ) ₃ SiO _1/2 units, (CH ₃ ) ₂ HSiO _1/2 units and (CH ₃ ) ₃ SiO _1/2 units ( Examples thereof include copolymers composed of C ₆ H ₅ ) ₂ SiO _2/2 units, (CH ₃ ) HSiO _2/2 units, (CH ₃ ) ₂ SiO _2/2 units, and SiO _4/2 units.

The blending amount of the component (E) is such that the silicon-bonded hydrogen atom in the component (E) is 0.3 to 2.0 with respect to one silicon-bonded alkenyl group in the component (D). The amount is preferably 0.4 to 1.5, and more preferably 0.5 to 1.0. When the number of silicon atom-bonded hydrogen atoms is less than 0.3, the crosslinking density becomes too low, and the resulting heat conductive silicone composition has poor resistance to slippage. This is because the viscosity of the thermally conductive silicone composition becomes too high, and the handleability becomes poor.
The organohydrogenpolysiloxane of this component may be used alone or in combination of two or more.

[(F) Platinum-based catalyst]
The component (F) is a component for promoting the addition reaction between the silicon atom-bonded alkenyl group in the component (D) and the silicon atom-bonded hydrogen atom in the component (E). The component (F) is a platinum-based catalyst, specifically platinum and / or a platinum-based compound.
As the platinum and platinum-based compounds, conventionally known compounds can be used. Specifically, for example, platinum black; chloroplatinic acid; alcohol-modified chloroplatinic acid; chloroplatinic acid and olefin aldehyde, vinylsiloxane And complexes of acetylene alcohols and the like.

The blending amount of the component (F) may be an effective amount, and may be appropriately increased or decreased depending on the desired curing rate, but is usually 0.1 to 1 in terms of the mass of platinum atoms relative to the component (D). 1,000 ppm, preferably 1 to 300 ppm. If the amount is too small, the addition reaction may be remarkably slow or may not be crosslinked. When the amount is too large, not only the heat resistance of the cured product is lowered, but also platinum is expensive, which is disadvantageous in terms of cost.
The platinum catalyst of this component may be used individually by 1 type, or may use 2 or more types together.

[Other optional ingredients]
In the case of obtaining the component (A) of the present invention, a reaction control agent may be used in addition to the above components (D) to (F). As the reaction control agent, a conventionally known reaction control agent used in addition-curable silicone compositions can be used. For example, acetylene compounds such as acetylene alcohols (for example, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol), various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole And organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

The silicone gel crosslinked product of component (A) is crosslinked by heating (D) component and (E) component in the presence of platinum catalyst of component (F), that is, hydrosilylation reaction (addition reaction). It is obtained by progressing. The reaction temperature is usually about 50 to 180 ° C., but is not limited thereto. Although the reaction time is affected by the heating temperature, usually the reaction proceeds sufficiently in 0.5 to 12 hours. What has been subjected to such treatment is defined as "crosslinked product".

Although the details of the component (B) and the component (C) will be described later, after the component (D) and the component (E) are cross-linked to obtain the component (A), the component (B) and the component (C) are mixed. Alternatively, in order to obtain the component (A), the component (B) is added before heating, the components (D) and (E) are heated and mixed, and then the component (C) is mixed. In addition, in order to obtain the component (A), all of the component (B) and the component (C) may be added in advance before heating, and then the components (D) and (E) may be heated and mixed. In view of efficiency, this last method is most preferable.

[Component (B)]
Component (B) is a component that does not participate in crosslinking of the above components (D) and (E), and is therefore a silicone oil that does not contain an aliphatic unsaturated bond and SiH group, and is represented by the following general formula (1). It is preferable to be a one-terminal trifunctional hydrolyzable organopolysiloxane.

Wherein R ¹ is independently an alkyl group having 1 to 6 carbon atoms, and R ² is each independently an unsubstituted or substituted monovalent group having no aliphatic unsaturated bond having 1 to 18 carbon atoms. One or more groups selected from the group of hydrocarbon groups, a is an integer of 5 to 120)

The organopolysiloxane of the general formula (1) is used for treating the surface of the thermally conductive filler of the component (C), but not only helps to increase the powder filling but also covers the powder surface. This makes it difficult for the powders to agglomerate and the effect persists even at high temperatures, and therefore has the function of improving the heat resistance of the thermally conductive silicone composition of the present invention.

In the above formula (1), R ¹ includes, for example, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, and a propyl group, and a methyl group and an ethyl group are particularly preferable. R ² is independently of each other an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 14 carbon atoms, and having no aliphatic unsaturated bond. Specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group. An alkyl group such as phenyl group, tolyl group, xylyl group, naphthyl group, etc .; aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group; some or all of hydrogen atoms of these groups are fluorine And a 3,3,3-trifluoropropyl group substituted with a halogen atom such as chlorine, preferably an alkyl group, an aryl group, or a 3,3,3-trifluoropropyl group, more preferably methyl Group, phenyl group and 3,3,3-trifluoropropyl group.
a is an integer of 5 to 120, preferably an integer of 10 to 90.

The kinematic viscosity is preferably 5 ~ 500mm ² / s at 25 ° C. of component (B), more preferably 10 ~ 300mm ² / s, more preferably 10 ~ 100mm ² / s.

The blending amount when component (B) silicone oil is blended is preferably in the range of 201 to 500 parts by weight, more preferably 210 to 450 parts by weight, still more preferably 100 parts by weight of component (A). 220 to 400 parts by mass. When the amount is less than 201 parts by mass, the viscosity of the resulting composition is increased and the handleability is poor, and when the amount is more than 500 parts by mass, the misalignment resistance of the composition is deteriorated.
As the silicone oil not involved in the crosslinking, a component (G) having no reactive group may be added in addition to the above-mentioned trifunctional hydrolyzable organopolysiloxane.

[Component (G)]
Component nonfunctional liquid silicone oil (G) is 25 kinematic viscosity at ℃ is 10 ~ 500,000mm ² / s, preferably 30 ~ 10,000mm ² / s, more preferably 50 ~ 5,000mm ² / s Is an organopolysiloxane having When the kinematic viscosity of the organopolysiloxane is lower than the lower limit, oil bleeding of the obtained heat conductive silicone composition is facilitated. Moreover, when larger than the said upper limit, the viscosity of the composition obtained will become high too much and it will become a thing with bad handleability.

The silicone oil (G) is not particularly limited as long as it has the above kinematic viscosity, and conventionally known organopolysiloxanes can be used. The molecular structure of the organopolysiloxane (silicone oil) is not particularly limited, and may be any of linear, branched, and cyclic. In particular, the main chain is preferably composed of a repeating diorganosiloxane unit and has a linear structure in which both ends of the molecular chain are blocked with a triorganosiloxy group. These organopolysiloxanes may be used alone or in combination of two or more.

The organopolysiloxane as the non-functional liquid silicone oil can be represented by the following average composition formula (6).
R ⁷ _g SiO _{(4-g) / 2} (6)
In the above formula (6), R ⁷ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 14 carbon atoms, and having no aliphatic unsaturated bond. Specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group. An alkyl group such as phenyl group, tolyl group, xylyl group, naphthyl group, etc .; aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group; some or all of hydrogen atoms of these groups are fluorine And a 3,3,3-trifluoropropyl group substituted with a halogen atom such as chlorine, preferably an alkyl group, an aryl group, or a 3,3,3-trifluoropropyl group, more preferably methyl Group, phenyl group and 3,3,3-trifluoropropyl group.

In the above formula (6), g is a number in the range of 1.8 to 2.2, particularly in the range of 1.9 to 2.1. By making g into the said range, the heat conductive silicone composition obtained can have the favorable kinematic viscosity requested | required.

The organopolysiloxane represented by the average composition formula (6) is preferably a linear organopolysiloxane represented by the following formula (7).

In the above formula (7), R ^{8 s} are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 14 carbon atoms, and having no aliphatic unsaturated bond. Examples of the monovalent hydrocarbon group include the groups described above. Of these, all R ⁸ are preferably methyl groups. h is the organo kinematic viscosity at 25 ° C. polysiloxane 10 ~ 500,000mm ² / s, preferably 30 ~ 10,000mm ² / s, more preferably a number which is a 100 ~ 8,000mm ² / s.

When the component (G) is blended, the content thereof is preferably 10 to 500 parts by weight, more preferably 50 to 400 parts by weight, and still more preferably 100 to 300 parts by weight with respect to 100 parts by weight of the component (A). Part by mass.

[Component (C)]
The thermally conductive filler of component (C) is for imparting thermal conductivity to the thermally conductive silicone composition of the present invention. Examples of the thermally conductive filler include aluminum, silver, copper, nickel, zinc oxide, alumina, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, diamond, and graphite. These may be used alone or in combination of two or more. May be used in combination. These heat conductive fillers preferably have an average particle size of 0.1 to 150 μm, more preferably 1 to 120 μm. If the average particle size is too small, the viscosity of the composition becomes too high and the handleability is poor, and if it is too large, the resulting composition tends to be non-uniform. Moreover, the shape of these heat conductive fillers may be either spherical or indefinite.

In the present invention, “average particle diameter” means a particle diameter at an integrated value of 50% in a volume-based particle size distribution obtained by a laser diffraction / scattering method. Measurement by the laser diffraction / scattering method may be performed by, for example, a microtrack particle size analyzer MT3300EX (manufactured by Nikkiso Co., Ltd.).

If the blending amount of component (C) is less than 2,001 parts by mass with respect to 100 parts by mass of component (A), the resulting thermal conductivity will be low, and if it is greater than 10,000 parts by mass, the viscosity will be low. Since it becomes too high and the handleability deteriorates, the range of 2,001 to 10,000 parts by mass is preferable. The amount is more preferably 2,100 to 9,000 parts by mass, still more preferably 2,200 to 8,000 parts by mass, and particularly preferably 2,200 to 6,000 parts by mass.

The heat conductive silicone composition of the present invention preferably has a viscosity at 25 ° C. of 100 to 1,500 Pa · s. More preferably, it is 200 to 1,000 Pa · s, and still more preferably 200 to 900 Pa · s. If it is less than 100 Pa · s, misalignment resistance is deteriorated, and if it is greater than 1,500 Pa · s, handleability is deteriorated. In addition, this viscosity value is a value by a rotational viscometer (Malcom viscometer mentioned later).
The thermal conductivity of the thermally conductive silicone composition of the present invention is 1.0 W / mK or more, preferably 1.5 W / mK or more because there is no sufficient heat dissipation effect if it is less than 1.0 W / mK.

In order to produce the heat conductive silicone composition of the present invention, each of the above components is mixed with Trimix, Twin Mix, Planetary Mixer (all are registered trademarks of a mixer manufactured by Inoue Mfg. Co., Ltd.), Ultra Mixer (Mizuho Industry ( It can be obtained by stirring and mixing in the above-mentioned procedures and conditions in a mixer such as a registered trademark of a mixer manufactured by the same company), Hibis Disper Mix (registered trademark of a mixer manufactured by Special Machine Industries Co., Ltd.), etc. it can.
In this case, the above-described thermally conductive silicone composition having the Tan δ value of the present invention is obtained by selecting the above-described components (A) to (C) and appropriately selecting the blending amount within the above-mentioned range. Can do.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
The test relating to the present invention was performed as follows.

[Tanδ]
Using a viscoelasticity measuring device (model name: HAAKE MAS) manufactured by Thermo Fisher Scientific, using a circular parallel plate with a strain amount of 0.5% and a diameter of 20 mm, at a temperature of 25 ° C. and a material thickness of 1 mm, The loss coefficient Tanδ at a frequency was measured, and Tanδ at a frequency of 0.2 Hertz was taken as a value.

〔Thermal conductivity〕
The thermal conductivity was measured at 25 ° C. using TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd.

(Average particle size measurement)
The average particle diameter measurement is a volume-based cumulative average diameter measured by Microtrac MT3300EX, which is a particle size analyzer manufactured by Nikkiso Co., Ltd.

[Displacement]
A 2 mm spacer is provided, and a thermally conductive silicone composition is sandwiched between two slide glass plates so as to form a circle having a diameter of 1.5 cm. The test piece is tilted by 90 degrees with respect to the ground. It was placed in a thermal shock tester (model number: TSE-11-A) manufactured by ESPEC Co., Ltd., which was set so as to alternately repeat at 125 ° C. and 30 ° C. (30 minutes each), and a 500 cycle test was conducted. After 500 cycles, how much the thermally conductive silicone composition shifted from its original location was measured.
<Standard>
If it is 1 mm or less, it can be said that the displacement resistance is excellent.

[Appearance after displacement test]
The state of the thermally conductive silicone composition after 500 cycles was observed.
In the composition, a state having no voids or cracks was evaluated as ◯, and a state having voids or cracks was evaluated as ×.

[Viscosity of thermally conductive silicone composition]
The viscosity of the thermally conductive silicone composition was measured at 25 ° C. using a Malcolm viscometer (type PC-10AA).

[Examples 1 to 6, Comparative Examples 1 to 4]
As shown in Tables 1 and 2, each component was charged into a planetary mixer, and a heat conductive silicone composition was prepared by the following procedure.
That is, the component (B), the component (C), the component (D), and the component (G) as necessary were put into a planetary mixer and stirred at room temperature for 10 minutes. Thereafter, the components (E) and (F) are added, the temperature is raised to 170 ° C., and the mixture is heated and mixed as it is for 2 hours to cause the hydrosilylation reaction by the components (D) and (E) to be performed. A crosslinked silicone gel (A) was prepared to obtain a composition. The various tests mentioned above were done using the obtained composition. The results are shown in Tables 1 and 2.

[Component (B)]
(B-1)

Kinematic viscosity 35mm ² / s

[Component (C)]
(C-1) Alumina powder (average particle size: 140 μm)
(C-2) Alumina powder (average particle size: 110 μm)
(C-3) Alumina powder (average particle size: 45 μm)
(C-4) Alumina powder (average particle size: 10 μm)
(C-5) Alumina powder (average particle size: 1.5 μm)
(C-6) Zinc oxide powder (average particle size: 1.0 μm)

[(D) component]
(D-1)
A linear dimethylpolysiloxane having a kinematic viscosity of 600 mm ² / s having vinyl groups at both ends.
(D-2)
A linear dimethylpolysiloxane having a linear kinematic viscosity of 30,000 mm ² / s and having vinyl groups at both ends.

[(E) component]
(E-1)

α / β = 0.35, kinematic viscosity 113 mm ² / s
(E-2)

α / β = 0.13, kinematic viscosity 25 mm ² / s
(E-3) <For comparative example>

α / β = 0.09, kinematic viscosity 28 mm ² / s
(E-4) <For comparative example>

α / β = 0.06, kinematic viscosity 72 mm ² / s

[(F) component]
(F-1)
A solution in which a platinum-divinyltetramethyldisiloxane complex is dissolved in the same dimethylpolysiloxane as (D-1) (platinum atom content: 1% by mass).

[Component (G)]
(G-1)
A linear 1,000 mm ² / s dimethylpolysiloxane having trimethylsilyl groups at both ends.

* The number of silicon atom-bonded hydrogen atoms in component (E) with respect to one silicon-bonded alkenyl group in component (D) is denoted as H / Vi for convenience (the same applies hereinafter).

Claims

(A) a silicone gel crosslinked product,
(B) Silicone oil that does not contain an aliphatic unsaturated bond and SiH group, and serves as a surface treatment agent for the following component (C):
(C) A thermally conductive silicone composition comprising a thermally conductive filler and having a loss coefficient Tanδ at a frequency of 0.2 hertz at 25 ° C. measured by a viscoelasticity measuring device is 2.0 or less.
(A) Silicone gel crosslinked product: 100 parts by mass,
(B) Silicone oil comprising a one-end hydrolyzable organopolysiloxane represented by the following general formula (1): 201 to 500 parts by mass,

Wherein R 1 is independently an alkyl group having 1 to 6 carbon atoms, and R 2 is each independently an unsubstituted or substituted monovalent group having no aliphatic unsaturated bond having 1 to 18 carbon atoms. One or more groups selected from the group of hydrocarbon groups, a is an integer of 5 to 120)
2. The heat conductive silicone composition according to claim 1, comprising (C) a heat conductive filler having an average particle size of 0.1 to 150 μm: 2,001 to 10,000 parts by mass.
The thermally conductive silicone composition according to claim 1 or 2, wherein the component (A) is a silicone gel crosslinked product of the following components (D) and (E).
(D) The following average composition formula (2)
R 3 b R 4 c SiO (4-bc) / 2 (2)
(Wherein R 3 represents an alkenyl group, R 4 represents an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and b is a number of 0.0001 to 0.2. And c is a number from 1.7 to 2.2, where b + c is a number satisfying 1.9 to 2.4.)
An organopolysiloxane having at least one alkenyl group bonded to a silicon atom represented by
(E) At least 4 hydrogen atoms bonded to a silicon atom at the non-terminal end of the molecular chain are contained in one molecule, and the following formula (3)
0.1 <α / β (3)
(In the formula, α represents the number of hydrogen atoms bonded to non-terminal silicon atoms of the molecular chain, and β represents the total number of silicon atoms in the component (E).)
Organohydrogenpolysiloxane satisfying the following: 0.3 to 2.0 hydrogen atoms bonded to silicon atoms in component (E) for one alkenyl group bonded to silicon atoms in component (D) Amount to be.
Furthermore, (G) 10 to 500 parts by mass of non-functional liquid silicone oil having a kinematic viscosity at 25 ° C. of 10 to 500,000 mm 2 / s with respect to 100 parts by mass of component (A). 4. The thermally conductive silicone composition according to any one of 3 above.
The thermally conductive silicone composition according to any one of claims 1 to 4, which has a viscosity at 25 ° C of 100 to 1,500 Pa · s.