TW201903117A - Thermally conductive polyoxo composition - Google Patents

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 Tan[delta] at a frequency of 0.2 Hz at 25 DEG 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 polysiloxane composition

The present invention relates to a thermally conductive polysiloxane composition excellent in offset resistance.

In general, electrical and electronic parts generate heat during use. Therefore, in order to make electrical parts operate properly, it is necessary to remove heat. Various thermally conductive materials for removing heat are proposed. This thermally conductive material is roughly divided into two types: 1) a sheet-like one that is easy to handle and 2) a paste-like one.

The sheet-like system has the advantages of easy operation and excellent stability. However, since the contact thermal resistance is increased in nature, the heat dissipation performance is inferior to that of the paste-like system. In addition, in order to maintain the sheet shape, it is necessary to have a certain degree of strength/hardness, which cannot absorb the tolerances generated between the components of the electrical and electronic components and the heat dissipation member, and may damage the components due to such stress.

On the other hand, paste-like ones, such as the use of coating equipment, can be adapted to mass production, and because of low contact thermal resistance, excellent heat dissipation performance. However, in the case of mass production such as screen printing, the viscosity of the paste is lower is better, but in this case, the paste will shift due to the thermal shock of the device (pump out phenomenon), because Fully remove the heat, the result will be as if the component will malfunction. In addition, as the past technology, polysiloxane compositions such as the following have been proposed, but at present, it is required to give more sufficient performance and a thermally conductive polysiloxane composition excellent in offset resistance. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3948642 [Patent Document 2] Japanese Patent No. 3195277 [Patent Document 3] Japanese Patent Laid-Open No. 2000-169873 [Patent Document 4] Japanese Patent Laid-Open No. 2006-143978 [Patent Document 5] Japanese Patent Laid-Open No. 2004-210856 [Patent Document 6] Japanese Patent Laid-Open No. 2005-162975 [Patent Document 7] Japanese Patent No. 5300408 [Patent Document 8] Japanese Patent No. 4976704 [Patent Document 9 ] Japanese Patent No. 3541390 [Patent Document 10] Japanese Patent No. 4130091 [Patent Document 11] Japanese Patent No. 5388329

[Problems to be solved by the invention]

The present invention is made in view of the above-mentioned matters, and its object is to provide a thermally conductive polysiloxane composition excellent in offset resistance. [Means to solve the problem]

The inventors are devoted to the results of the research in order to achieve the above objectives, and found that it contains polysiloxane gel crosslinks, specific silicone oils, especially single-terminal hydrolyzable organic polysiloxanes, and thermally conductive fillers, and in At a specific frequency, a composition exhibiting a specific loss coefficient Tan δ value has fluidity, and at the same time, the offset resistance is dramatically improved, and the present invention has been completed.

Therefore, the present invention provides the following thermally conductive polysiloxane composition. [1] A thermally conductive polysiloxane composition comprising (A) a cross-linked polysiloxane gel, (B) each does not contain an aliphatic unsaturated bond and a SiH group, as the following components (C ) Is a silicone oil with a surface treatment agent and (C) a thermally conductive filler. The loss coefficient Tanδ at a frequency of 25 Hz at 0.2°C obtained by a viscoelasticity measuring device is 2.0 or less. [2] The thermally conductive polysiloxane composition as described in [1], which contains (A) a polysiloxane gel cross-linked product: 100 parts by mass, (B) a single terminal represented by the following general formula (1) Silicone oil composed of hydrolyzable organic polysiloxane: 201~500 parts by mass, (In the formula, R ¹ is independently an alkyl group having 1 to 6 carbon atoms, and R ² is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms which does not have an aliphatic unsaturated bond. Choose one or more than one base in the group, a is an integer from 5 to 120.) (C) Thermally conductive filler with an average particle size of 0.1 to 150 μm: 2,001 to 10,000 parts by mass. [3] The thermally conductive polysiloxane composition according to [1] or [2], wherein the component (A) is a cross-linked polysiloxane gel of the following components (D) and (E), (D ) An organic polysiloxane containing at least one alkenyl group bonded to a silicon atom in one molecule as shown in the following average composition formula (2), (In the formula, R ³ represents an alkenyl group, R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, b is 0.0001 to 0.2, c is 1.7 to 2.2, but b +c is a number that satisfies 1.9 to 2.4.) (E) An organic hydrogen polymer having at least 4 hydrogen atoms bonded to a silicon atom at the non-terminal of the molecular chain in one molecule and satisfying the following formula (3) Siloxane, (In the formula, α represents the number of hydrogen atoms bonded to the silicon atoms at the non-terminal of the molecular chain, and β represents the number of total silicon atoms in the (E) component.): Relative to the bonded in the (D) component There is one alkenyl group in the silicon atom, and the amount of hydrogen atoms bonded to the silicon atom in the (E) component is 0.3 to 2.0. [4] The thermally conductive polysiloxane composition according to any one of [1] to [3], which further contains 10 to 500 parts by mass of (G) relative to 100 parts by mass of component (A) at 25°C Non-functional liquid silicone oil with a dynamic viscosity of 10～500,000mm ² /s. [5] The thermally conductive polysiloxane composition according to any one of [1] to [4], which has a viscosity of 100 to 1,500 Pa·s at 25°C. [Effect of invention]

The thermally conductive polysiloxane composition of the present invention has fluidity, and at the same time, it can be seen that the offset resistance is greatly improved.

Hereinafter, the present invention will be described in detail. In the thermally conductive polysiloxane composition of the present invention, the offset resistance is related to the value of the loss coefficient Tan δ. If the loss coefficient Tan δ at a frequency of 25 Hz at 25°C obtained by a viscoelasticity measuring device is greater than 2.0, the resistance Offset becomes worse. Therefore, the Tanδ system 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 Tanδ is not particularly limited, but it is usually 0.8 or more, especially 1.0 or more. For convenience, the Tan δ at 0.2 Hz is specified, but since the Tan δ of each of the 0.1 to 0.5 Hz regions does not change significantly, there is no problem in specifying the Tan δ value at any frequency if it falls within this range.

Here, Tan δ is a measurement value obtained by a viscoelasticity measuring device. Especially in the case of the present invention, a viscoelasticity measuring device (module name: HAAKE MAS) manufactured by Thermo Fisher Scientific Co., Ltd. is used, and the strain variable 0.5%, For a circular parallel plate with a diameter of 20 mm, at a temperature of 25° C. and a material thickness of 1 mm, the loss coefficient Tan δ at each frequency is measured, and Tan δ at a frequency of 0.2 Hz is set as the value.

In the present invention, in order to obtain the above-mentioned loss coefficient Tanδ, the thermally conductive polysiloxane composition contains (A) a polysiloxane gel cross-linked product, 　　 (B) each does not contain an aliphatic unsaturated bond and a SiH group, as Silicone oil of the surface treatment agent of the following component (C), 　　 (C) thermally conductive filler.

Hereinafter, each component will be described in detail. [Component (A)] The crosslinked polysiloxane gel is used as the matrix of the thermally conductive polysiloxane composition of the present invention. The component (A) is obtained by subjecting the following (D) component and (E) component to the hydrosilylation reaction (addition reaction) in the presence of the (F) component. (D) An organic polysiloxane containing at least one alkenyl group bonded to a silicon atom in one molecule as shown in the following average composition formula (2), (In the formula, R ³ represents an alkenyl group, R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, b is 0.0001 to 0.2, c is 1.7 to 2.2, but b +c is a number that satisfies 1.9 to 2.4.) (E) An organic hydrogen polymer having at least 4 hydrogen atoms bonded to a silicon atom at the non-terminal of the molecular chain in one molecule and satisfying the following formula (3) Siloxane, (In the formula, α represents the number of hydrogen atoms bonded to the silicon atoms at the non-terminal of the molecular chain, and β represents the number of total silicon atoms in the (E) component.): Relative to the bonded in the (D) component One alkenyl group in silicon atom, the hydrogen atom bonded to the silicon atom in the (E) component becomes an amount of 0.3 to 2.0, (F) platinum-based catalyst: effective amount.

[Component (D)] The component (D) is a component that becomes the main component of the component (A). (D) The component is an organic having at least one alkenyl group bonded to a silicon atom in one molecule (hereinafter, referred to as "alkenyl group bonded to silicon atom") represented by the above average composition formula (2) Polysiloxane. The aforementioned alkenyl group is preferably at least 2 in one molecule, more preferably 2 to 50, and particularly preferably 2 to 20. These alkenyl groups may be bonded to the silicon atom at the end of the molecular chain, may also be bonded to the silicon atom at the non-terminal of the molecular chain (that is, at both ends of the molecular chain), or may be a combination of these.

In the above formula (2), R ³ usually represents an alkenyl group having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms. Examples of this specific example include lower alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, and isobutenyl, and vinyl is preferred. R ⁴ usually represents a carbon number of 1 to 12, ideally 1 to 10, and more preferably 1 to 6, an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond. Examples of the specific examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, hexyl, cyclohexyl, octyl, decyl, and dodecane. Alkyl groups such as phenyl; aryl groups such as phenyl and tolyl; aralkyl groups such as benzyl and phenylethyl; some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine and chlorine Chloromethyl, 3,3,3-trifluoropropyl, etc., but from the viewpoint of ease of synthesis, methyl, phenyl, 3,3,3-trifluoropropyl are ideal.

In the above formula (2), the values of b, c, and b+c are as described above, but b is ideally a number of 0.0005 to 0.1, c is ideally a number of 1.9 to 2.0, and b+c satisfies 1.95 to 2.05 The number is ideal.

The molecular structure of the organic polysiloxane of this component is not particularly limited, and may be linear; a part of the molecular chain contains R ³ SiO _3/2 units, R ⁴ SiO _3/2 units, SiO ₂ units (where , The groups represented by R ³ and R ⁴ are in accordance with those defined above.), branched; ring-shaped; three-dimensional network (resin-like), etc., but usually the main chain is basically composed of repeated It is composed of two organosiloxane units, and the two ends of the molecular chain are straight-chain two organopolysiloxanes closed with triorganosiloxane groups.

The dynamic viscosity of the organic polysiloxane of this component is preferably 50 to 100,000 mm ² /s at 25°C, more preferably 100 to 10,000 mm ² /s, and more preferably 100 to 1,000 mm ² /s. In the case where the dynamic viscosity is 50 to 100,000 mm ² /s, the fluidity and workability of the obtained hardened system become more excellent. Still, this kinematic viscosity is the value at 25°C (hereinafter the same) that can be obtained with an Oswald viscometer.

Examples of the organic polysiloxane based on this component satisfying the above requirements include those represented by the following general formula (4). (In the formula, R ⁵ independently represents an unsubstituted or substituted monovalent hydrocarbon group, but at least one of R ⁵ is preferably at least two of which are alkenyl groups, and d is an integer of 20 to 2,000.) In this formula ( 4), the unsubstituted or substituted monovalent hydrocarbon group represented by R ^{5 is} defined by the aforementioned R ³ (alkenyl group) and R ⁴ (unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond) The same, the carbon number and specific examples are also the same. In addition, d is ideally 40 to 1,200, more preferably 50 to 600 integer.

The specific examples of the organic polysiloxane represented by the above formula (4) include dimethylvinyl siloxane-blocked dimethyl polysiloxane at both ends of the molecular chain, and trimethyl silane at the single end of the molecular chain. Oxygen‧Single-terminal dimethylvinylsiloxyoxy blocked dimethylpolysiloxane, Molecular chain both ends trimethylalkoxy-blocked dimethylsiloxane‧Methylvinylsiloxane copolymer, Trimethylsilyloxy at one end of molecular chain‧Dimethylvinylsiloxyl at one end Blocked dimethylsiloxane‧Copolymer of methylvinylsiloxane and dimethylvinylsiloxy at both ends of molecular chain Base-blocked dimethylsiloxane‧methylvinylsiloxane copolymer, molecular chain ends dimethylvinylsiloxane-blocked dimethylsiloxane‧diphenylsiloxane copolymer, etc.　　The organic polysiloxane of this component can be used alone or in combination of two or more.

[(E) component] The (E) component reacts with the aforementioned (D) component and acts as a crosslinking agent. (E) The component is a hydrogen atom that has been bonded to a silicon atom at the non-terminal of the molecular chain (that is, it is a SiH group, hereinafter referred to as "a hydrogen atom bonded to a silicon atom"). If there are 3 in 1 molecule In the following, sufficient offset resistance cannot be exerted, so at least four are required. And, it is an organic hydrogen polysiloxane satisfying the following formula (3). (In the formula, α represents the number of hydrogen atoms bonded to silicon atoms at the non-terminal of the molecular chain, and β represents the number of total silicon atoms in the (E) component.) The range of the above α/β is as small as 0.1 In the following cases, since the offset resistance of the present composition is deteriorated, 0.1<α/β is also required. In this case, the α/β system is preferably 0.11 or more, particularly 0.12 or more, and the upper limit system is not particularly limited, but 0.95 or less, especially 0.90 or less, and particularly 0.5 or less.

The molecular structure of this component is not particularly limited as long as it satisfies the above requirements. For example, it may be any of a straight chain shape, a ring shape, a branch shape, a three-dimensional network (resin shape), etc., which are generally known in the past. Among them, especially from the viewpoint of the workability and the offset resistance of the hardened product obtained by crosslinking (D) component, the number of silicon atoms (or degree of polymerization) in 1 molecule is usually 3 to 1,000 The number is ideally 5 to 400, more ideally 10 to 300, more ideally 10 to 100, and particularly ideal 10 to 60.

The dynamic viscosity of the organic hydrogen polysiloxane of this component is usually 1 to 10,000 mm ² /s, ideally 3 to 5,000 mm ² /s, more preferably 5 to 3,000 mm ² /s, more preferably 10 to 1,000 mm ² /s, it is best to be liquid at room temperature (25℃).

As the organic hydrogen polysiloxane system satisfying the above requirements, for example, those represented by the following average composition formula (5) are preferable. (In the formula, R ⁶ represents an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, e is a number of 0.7 to 2.2, f is a number of 0.001 to 0.5, but e+f is 0.8 to 2.5 Number.)

In the above formula (5), R ⁶ generally represents a carbon number of 1 to 10, preferably 1 to 6, an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond. The specific examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, Alkyl groups such as decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and hydrogen atoms of these groups 3,3,3-trifluoropropyl, etc. partially or entirely substituted with halogen atoms such as fluorine, chlorine, etc., preferably alkyl, aryl, 3,3,3-trifluoropropyl, more preferably methyl, Phenyl, 3,3,3-trifluoropropyl.

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

The molecular structure of the organic hydrogen polysiloxane represented by the above formula (5) is not particularly limited, and may be any of linear, cyclic, bifurcated, three-dimensional network (resin) and the like. Among them, the number of silicon atoms in one molecule and the kinematic viscosity are ideal to satisfy the above-mentioned range, especially the linear ones.

As a specific example of the organic hydrogen polysiloxane represented by the above formula (5), a dimethylhydrosiloxy-blocked dimethylsiloxane‧methylhydrosiloxane copolymer at both ends of the molecular chain can be given. 、Both ends of the molecular chain dimethylhydrosiloxyl group block methylhydrosiloxane‧Dimethylsiloxane‧Diphenylsiloxane copolymer、One end of the molecular chain dimethylhydrosilyloxy‧Single end Trimethylsilyloxy-blocked dimethylsiloxane‧Methylhydrosiloxane copolymer, molecular chain single-ended dimethylhydrosilyloxy‧Single-ended trimethylsilyloxy blocked methylhydrosiloxane ‧Dimethylsiloxane‧Diphenylsiloxane copolymer, consisting of (CH ₃ ) ₂ HSiO _1/2 unit and (CH ₃ ) ₃ SiO _1/2 unit and (CH ₃ )HSiO _2/2 unit and Copolymer composed of SiO _4/2 units, consisting of (CH ₃ ) ₂ HSiO _1/2 units and (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) HSiO _2/2 units and (CH ₃ ) ₂ SiO Copolymer composed of _2/2 units and SiO _4/2 units, consisting of (CH ₃ ) ₂ HSiO _1/2 units and (CH ₃ ) HSiO _2/2 units and (CH ₃ ) ₂ SiO _2/2 units and SiO A copolymer composed of _4/2 units, consisting of (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units and (CH ₃ ) HSiO _2/2 units and (CH ₃ ) ₂ SiO _2/2 units and ( C ₆ H ₅ ) ₃ SiO _1/2 unit copolymer, consisting of (CH ₃ ) ₂ HSiO _1/2 unit and (CH ₃ ) ₃ SiO _1/2 unit and (C ₆ H ₅ ) ₂ SiO _2/ A copolymer composed of ₂ units and (CH ₃ )HSiO _2/2 units and (CH ₃ ) ₂ SiO _2/2 units and SiO _4/2 units.

(E) The blending amount of the component is relative to one alkenyl group of the bonded silicon atom in the (D) component, and the amount of hydrogen atoms of the bonded silicon atom in the (E) component becomes 0.3 to 2.0, ideally The amount of 0.4 to 1.5 is more preferably 0.5 to 1.0. In the case where there are less than 0.3 hydrogen atoms bonded to silicon atoms, the crosslink density becomes too low, and the resulting thermally conductive polysiloxane composition has poor offset resistance, and if there are more than 2.0 The viscosity of the resulting thermally conductive polysiloxane composition becomes too high, so the operability becomes poor.　　The organic hydrogen polysiloxane of this component can be used alone or in combination of two or more.

[(F) Platinum catalyst] 　　 (F) component is to promote the addition reaction of the alkenyl group of the bonded silicon atom in the aforementioned (D) component and the hydrogen atom of the bonded silicon atom in the aforementioned (E) component Ingredients. (F) The component is a platinum-based catalyst, specifically, platinum and/or a platinum-based compound. As the platinum and platinum-based compound systems, conventionally well-known ones can be used, and specific examples thereof include platinum black; chloroplatinic acid; alcohol-modified chloroplatinic acid; chloroplatinic acid, olefin aldehyde, and vinyl siloxane , Complex compounds such as acetylenic alcohols, etc.

(F) The compounding amount of the component may be an effective amount, and it may be appropriately increased or decreased according to the desired hardening rate. However, for the component (D), the mass conversion of platinum atoms is usually 0.1 to 1,000 ppm. The ideal is 1~300 ppm. If the blending amount is too small, the addition reaction may be significantly slowed, or may become non-crosslinked. If this amount is too large, not only will the heat resistance of the cured product decrease, but also because platinum is expensive, it will also be disadvantageous in terms of cost.　　The platinum-based catalyst system of this component may be used alone or in combination of two or more.

[Other arbitrary components] In the case of obtaining the component (A) of the present invention, in addition to the above components (D) to (F), a reaction control agent may be used. As the reaction control agent, a conventionally well-known reaction control agent used for an addition-hardening polysiloxane composition can be used. For example, acetylene compounds such as acetylene alcohols (for example, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol), tributylamine, Various nitrogen compounds such as tetramethylethylenediamine and benzotriazole, organic phosphorus compounds such as triphenylphosphine, oxime compounds, organic chlorine compounds, etc.

The cross-linked polysiloxane gel of component (A) can be cross-linked by heating and mixing the components (D) and (E) in the presence of the platinum catalyst of component (F), that is, hydrosilylation Available (addition reaction). The reaction temperature is usually about 50 to 180°C, but it is not limited to this. The reaction time is also affected by the temperature of heating, but usually the reaction is sufficiently conducted for 0.5 to 12 hours. A person who is processed in this way is defined as a "cross-linked product".

The details of the component (B) and the component (C) are described later, but after the component (D) and the component (E) are cross-linked to obtain the component (A), the component (B) and the component (C) may be mixed, and In order to obtain the component (A), before the component (B) is added before heating, the components (D) and (E) are heated and mixed, and then the component (C) may be mixed. Furthermore, in order to obtain the component (A), before heating After all the components (B) and (C) are added in advance, the components (D) and (E) may be heated and mixed. However, considering efficiency, this last method is the most ideal.

[Component (B)] The component (B) is a component that does not participate in the crosslinking of the above components (D) and (E), and therefore is a silicone oil that does not contain aliphatic unsaturated bonds and SiH groups, and is particularly based on the following general formula ( 1) The single-terminal 3-functional hydrolyzable organic polysiloxane shown is ideal. (In the formula, R ¹ is independently an alkyl group having 1 to 6 carbon atoms, and R ² is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms which does not have an aliphatic unsaturated bond. Select one or more than two bases in the group, a is an integer from 5 to 120.)

The organic polysiloxane of the general formula (1) is used to treat the surface of the thermally conductive filler of the component (C), but it not only assists in the high filling of the powder, but also it is difficult to produce powders by covering the powder surface Because the effect continues even at high temperatures, it has the effect of improving the heat resistance of the thermally conductive polysiloxane composition of the present invention.

In the above formula (1), R ^{1 is} , for example, a C 1-6 alkyl group such as a methyl group, an ethyl group, a propyl group, etc., but particularly preferably a methyl group and an ethyl group. R ² is an independently substituted, monovalent hydrocarbon group having a carbon number of 1 to 18, and ideally 1 to 14 unsubstituted or substituted without an aliphatic unsaturated bond. The specific examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, Alkyl groups such as decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and hydrogen atoms of these groups 3,3,3-trifluoropropyl, etc. partially or entirely substituted with halogen atoms such as fluorine, chlorine, etc., preferably alkyl, aryl, 3,3,3-trifluoropropyl, more preferably methyl, Phenyl, 3,3,3-trifluoropropyl. a is an integer of 5~120, ideally an integer of 10~90.

The component (B) has a kinematic viscosity at 25°C of 5 to 500 mm ² /s, preferably 10 to 300 mm ² /s, and 10 to 100 mm ² /s.

In the case of blending the silicone oil of component (B), the blending amount is relative to 100 parts by mass of component (A), and the range of 201 to 500 parts by mass is ideal, more preferably 210 to 450 parts by mass, and more ideally 220 to 400 parts by mass. . If it is less than 201 parts by mass, the viscosity of the resulting composition becomes high and becomes poor in operability, and if it exceeds 500 parts by mass, the offset resistance of the composition becomes poor.　　 As a silicone oil system that does not participate in the cross-linking, in addition to the aforementioned single-terminal trifunctional hydrolyzable organic polysiloxane, a component (G) having no reactive group may be added.

[Component (G)] The non-functional liquid silicone oil of component (G) has a dynamic viscosity at 25° C. of 10 to 500,000 mm ² /s, ideally 30 to 10,000 mm ² /s, more preferably 50 to 5,000 mm ² /s organic polysiloxane. If the dynamic viscosity of the organic polysiloxane is lower than the above lower limit, the resulting thermally conductive polysiloxane composition becomes liable to penetrate oil. Moreover, if it exceeds the said upper limit, the viscosity of the obtained composition will become too high and it will become inferior in handleability.

The above-mentioned silicone oil (G) may be one having the above-mentioned kinematic viscosity, and an organic polysiloxane generally known in the past may be used. The molecular structure of the organic polysiloxane (silicone oil) is not particularly limited, and it may be any of linear, branched, and cyclic. In particular, the main chain is composed of a repeat of diorganosilane units, and it is preferable to have a linear structure in which both ends of the molecular chain are closed with triorganosiloxy groups. The organic polysiloxane series may be used alone or in combination of two or more.

The organic polysiloxane as the non-functional liquid silicone oil can be represented by the following average composition formula (6). In the above formula (6), R ⁷ is a carbon number of 1 to 18, preferably 1 to 14, an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond. The specific examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, Alkyl groups such as decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and hydrogen atoms of these groups 3,3,3-trifluoropropyl, etc. partially or entirely substituted with halogen atoms such as fluorine, chlorine, etc., preferably alkyl, aryl, 3,3,3-trifluoropropyl, more preferably methyl, Phenyl, 3,3,3-trifluoropropyl.

In the above formula (6), g is a number in the range of 1.8 to 2.2, especially in the range of 1.9 to 2.1. When g is within the above range, the resulting thermally conductive polysiloxane composition can have the required good dynamic viscosity.

As the organic polysiloxane based on the above average composition formula (6), a linear organic polysiloxane represented by the following formula (7) is preferable. In the above formula (7), R ⁸ is independent of each other and has 1 to 18 carbon atoms, and it is ideally an unsubstituted or substituted monovalent hydrocarbon group having 1 to 14 aliphatic unsaturated bonds. Examples of the monovalent hydrocarbon group include the above-mentioned groups. Among them, it is particularly preferable that all R ⁸ series are methyl groups. h is the number of kinematic viscosity of the organic polysiloxane at 25° C. being 10 to 500,000 mm ² /s, ideally 30 to 10,000 mm ² /s, and more preferably 100 to 8,000 mm ² /s.

In the case of formulating component (G), the content is preferably 10 to 500 parts by mass relative to 100 parts by mass of component (A), more preferably 50 to 400 parts by mass, and more preferably 100 to 300 parts by mass.

[Component (C)] The thermally conductive filler of component (C) is to impart thermal conductivity to the thermally conductive polysiloxane composition of the present invention. Examples of the thermally conductive filler system include aluminum, silver, copper, nickel, zinc oxide, aluminum oxide, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, diamond, and graphite. One type of these systems can be used. Or it can be used in combination of 2 or more types. The average particle size of these thermally conductive fillers is preferably 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 becomes poor in handleability, and if it is too large, the resulting composition tends to become uneven. In addition, the shape of these thermally conductive fillers may be either spherical or irregular.

In the present invention, the "average particle diameter" means a particle diameter of 50% of the cumulative value of the volume-based particle size distribution obtained by the laser diffraction and scattering method. The measurement by the laser diffraction and scattering method may be performed by, for example, the Microtrac particle size analyzer MT3300EX (manufactured by Nikkiso Co., Ltd.).

The blending amount of component (C) is less than 2,001 parts by mass relative to 100 parts by mass of component (A), the resulting thermal conductivity becomes lower, and if it exceeds 10,000 parts by mass, the viscosity becomes too high, so operate The property becomes worse, so the range of 2,001 to 10,000 parts by mass is ideal. It is preferably 2,100 to 9,000 parts by mass, more preferably 2,200 to 8,000 parts by mass, and particularly preferably 2,200 to 6,000 parts by mass.

The viscosity of the thermally conductive polysiloxane composition of the present invention at 25°C is ideally 100 to 1,500 Pa‧s. The ideal value is 200~1,000Pa‧s, and the ideal value is 200~900Pa‧s. This is because if it is less than 100 Pa‧s, the offset resistance is deteriorated, and if it is greater than 1,500 Pa‧s, the operability becomes poor. Still, this viscosity value is a value obtained by a rotary viscometer (Malcom viscometer described later).　　 Furthermore, the thermal conductivity of the thermally conductive polysilicon composition of the present invention is less than 1.0 W/mK, so there is no sufficient heat dissipation effect, so it is 1.0 W/mK or more, preferably 1.5 W/mK or more.

In the manufacture of the thermally conductive polysiloxane composition of the present invention, the above-mentioned components are classified into TRI-MIX, TWIN MIX, PLANETARY MIXER (planetary mixer) (all are registered trademarks of Inoue Manufacturing Co., Ltd. mixer), ULTRA MIXER ( Mixers such as MIZUHO Industrial Co., Ltd. mixers, HIVIS DISPER MIX (Special Machine Chemical Co., Ltd. mixers registered trademarks), etc. can be obtained by mixing in the order and conditions as described above. In this case, the above-mentioned thermally conductive polysiloxane composition having the Tan δ value of the present invention selects the above-mentioned components (A) to (C), and can be obtained by appropriately selecting the blending amount within the above-mentioned range . [Example]

Examples and test examples are shown below, and the present invention will be specifically described, but the present invention is not limited to the following examples.　　 The test of the present invention was carried out as follows.

[Tanδ] 　　 Using a viscoelasticity measuring device (module name: HAAKE MAS) made by Thermo Fisher Scientific, using a circular parallel plate with a strain of 0.5% and a diameter of 20 mm, at a temperature of 25°C and a material thickness of 1 mm, measured at each frequency The loss coefficient Tanδ is set to a value of Tanδ at a frequency of 0.2 Hz.

[Thermal conductivity] 　　The thermal conductivity is measured by TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd., and all are measured at 25°C.

[Measurement of average particle diameter] The measurement of average particle diameter is the cumulative average of the volume basis measured by Microtrac MT3300EX of a particle size analyzer manufactured by Nikkiso Co., Ltd.

[Offset] 　　Set a 2mm spacer, hold the thermally conductive polysiloxane composition between the two glass slides in a round shape with a diameter of 1.5cm, and tilt the test piece to the ground by 90 degrees The method was placed in a thermal shock tester (model: TSE-11-A) manufactured by espec, which had been set to alternately repeat -40°C and 125°C (30 minutes each), and a 500-cycle test was performed. After 500 cycles, determine how far the thermally conductive polysiloxane composition deviated from the original location. <Standard> 　　 1mm or less can be said to be excellent in offset resistance.

[Appearance after offset test] 　　 Observe the state of the thermally conductive polysiloxane composition after the above 500 cycles. In the 　　 composition, the state without pores and cracks was evaluated as ○, and the state with pores or cracks was evaluated as ×.

[Viscosity of thermally conductive polysiloxane composition] 　　 The viscosity of thermally conductive polysiloxane composition is measured at 25°C using a Malcom viscometer (type PC-10AA) from MALCOM.

[Examples 1 to 6, Comparative Examples 1 to 4] As shown in Tables 1 and 2, each component was placed in PLANETARY MIXER, and the thermally conductive polysiloxane composition was prepared in the following order.　　 That is, the component (B), component (C), (D) component, and the necessary component (G) are put into PLANETARY MIXER, and they are first stirred at room temperature for 10 minutes. After adding the (E) component and (F) component, the temperature was raised to 170°C, and the mixture was heated and mixed as it is for 2 hours, and the component was prepared by the hydrosilylation reaction caused by the (D) and (E) components. (A) The polysiloxane gel cross-linked product to obtain a composition. The above-mentioned various tests were conducted using the obtained composition. Record the results in Tables 1 and 2.

[Component (B)] (B-1) Dynamic viscosity 35mm ² /s

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

[(D)component] (D-1) Straight-chain dimethyl polysiloxane with a vinyl dynamic viscosity of 600 mm ² /s at both ends. (D-2) Straight-chain dimethyl polysiloxane with a vinyl dynamic viscosity of 30,000 mm ² /s at both ends.

[(E)component] (E-1) α/β＝0.35, dynamic viscosity 113 mm ² /s (E-2) α/β = 0.13, dynamic viscosity 25 mm ² /s (E-3) ＜For comparison example＞ α/β＝0.09, dynamic viscosity 28 mm ² /s (E-4) ＜For comparison example＞ α/β＝0.06, dynamic viscosity 72 mm ² /s

[Component (F)] (F-1) 　　 A solution of platinum-divinyltetramethyldisilazane complex as described in (D-1) above, dissolved in dimethylpolysiloxane (platinum atom) Content: 1% by mass).

[Component (G)] (G-1) A linear dimethyl polysiloxane with a trimethylsilyl group at both ends of 1,000 mm ² /s.

Claims (5)

A thermally conductive polysiloxane composition, characterized in that it contains (A) polysiloxane gel cross-linked product, 　　 (B) does not contain aliphatic unsaturated bonds and SiH groups, as the surface of the following component (C) The silicone oil of the treatment agent is made of 　　(C) thermally conductive filler, and the loss coefficient Tanδ at a frequency of 0.2 Hz at 25°C obtained by a viscoelasticity measuring device is 2.0 or less. The thermally conductive polysiloxane composition according to claim 1, which contains (A) a cross-linked polysiloxane gel: 100 parts by mass, (B) a single-terminal hydrolyzable organic compound represented by the following general formula (1) Silicone oil composed of polysiloxane: 201~500 parts by mass, (In the formula, R ¹ is independently an alkyl group having 1 to 6 carbon atoms, and R ² is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms which does not have an aliphatic unsaturated bond. Select one or more bases in the group, a is an integer from 5 to 120) (C) Thermally conductive filler with an average particle size of 0.1 to 150 μm: 2,001 to 10,000 parts by mass. The thermally conductive polysiloxane composition according to claim 1 or 2, wherein component (A) is a polysiloxane gel cross-linked product of the following components (D) and (E), (D) with the following average composition The organic polysiloxane containing at least one alkenyl group bonded to a silicon atom in one molecule as shown in formula (2), (In the formula, R ³ represents an alkenyl group, R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, b is 0.0001 to 0.2, c is 1.7 to 2.2, but b +c is a number satisfying 1.9 to 2.4) (E) Organic hydrogen polysilicon having at least 4 hydrogen atoms bonded to silicon atoms at the non-terminal of the molecular chain in one molecule and satisfying the following formula (3) Oxane, (In the formula, α represents the number of hydrogen atoms bonded to silicon atoms at the non-terminal of the molecular chain, and β represents the number of total silicon atoms in the (E) component): relative to the (D) component that has been bonded to There is one alkenyl group of silicon atom, and the amount of hydrogen atoms bonded to the silicon atom in the (E) component is 0.3 to 2.0. The thermally conductive polysiloxane composition according to claim 1 or 2, wherein the dynamic viscosity at 25° C. is 10 to 500,000 mm ² with respect to 100 parts by mass of component (A) and further contains 10 to 500 parts by mass of (G). /s non-functional liquid silicone oil. If the thermally conductive polysiloxane composition of claim 1 or 2, its viscosity at 25°C is 100 to 1,500 Pa·s.