JP2023026805A - Heat-conductive silicone composition and heat-conductive silicone cured material - Google Patents

Abstract

To provide a heat-conductive silicone composition capable of suppressing viscosity increase of a composition when exposed to a high temperature for a long time, or capable of suppressing its hardness increase when a cured material of the composition is exposed to a high temperature for a long time.SOLUTION: A heat-conductive silicone composition comprise (A) an organopolysiloxane represented by the following general formula (1), (B) an organopolysiloxane represented by the following average composition formula (2), and (C) at least one heat-conductive filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon, wherein a total amount of components (A) and (B) is 3 to 90 mass% of all composition, and an amount of component (C) is 10 to 97 mass% of the total composition. R3bSiO(4-b)/2 (2)SELECTED DRAWING: None

Description

The present invention relates to a thermally conductive silicone composition and a cured thermally conductive silicone.

Heat generation during operation and resulting deterioration in performance are widely known as problems common to electronic component packages and power modules, and various heat dissipation techniques are used as means for solving this problem. In particular, a technique of arranging a cooling member in the vicinity of the heat-generating part, bringing them into close contact with each other, and efficiently dissipating heat from the cooling member is common.

At that time, if there is a gap between the heat-generating part and the cooling member, heat transfer is lowered due to the interposition of air with poor thermal conductivity, and the temperature of the heat-generating member cannot be lowered sufficiently. In order to prevent such intervening air and improve heat conduction, a heat-dissipating material with good thermal conductivity and conformability to the surface of the member, such as heat-dissipating grease and heat-dissipating sheet, is used (for example, Patent Document 1 ~9).

As a heat countermeasure for actual electronic component packages and power modules, thermal grease that is thin and compressible and has excellent penetrability into the gap between the heat-generating part and the cooling member is suitable from the viewpoint of heat radiation performance. On the other hand, heat dissipation grease may cause pumping out due to expansion and contraction due to the heat history of repeated heat generation and cooling in the heat generating part. By heat-hardening after compressing to a thickness, it is possible to make pumping-out difficult to occur and improve the reliability of electronic component packages and power modules (for example, Patent Document 10).

In recent years, there has been a demand for even higher thermal conductivity for heat dissipation grease in order to respond to new applications such as high output and high performance electronic component packages and power modules, semiconductors for self-driving vehicles, and IoT. In order to achieve high thermal conductivity, it is necessary to add a large amount of thermally conductive filler. In the case of (2), the viscosity increases, and in the case of the curable type, the hardness increases, and there is a risk that the adhesive will peel off from the heat-generating portion and reduce the reliability of the electronic component package or power module.

Based on the above background, we have developed a heat conductive material that can suppress the increase in the viscosity of the composition or the hardness of the cured product when exposed to high temperatures for a long time while having high thermal conductivity by blending a large amount of thermally conductive filler. There is a need for flexible silicone compositions.

JP-A-2002-327116 JP-A-2004-130646 JP 2009-234112 A Japanese Patent Application Laid-Open No. 2009-209230 JP 2010-095730 A JP 2008-031336 A Japanese Patent Application Laid-Open No. 2007-177001 Japanese Patent Application Laid-Open No. 2008-260798 JP 2009-209165 A JP 2016-053140 A

Therefore, the present invention has been made in view of the above circumstances, and is capable of suppressing the viscosity increase of the composition when exposed to high temperatures for a long time, or the cured product of the composition is exposed to high temperatures for a long time. An object of the present invention is to provide a thermally conductive silicone composition capable of suppressing an increase in hardness when it is used.

（式中、Ｒ^１は、独立に非置換または置換の炭素原子数１～１８の１価炭化水素基であり、Ｒ^２は、オキシラン環を有する基であり、Ｘは、ヘテロ原子を含んでもよい炭素原子数１～２０のアルキレン基であり、ａは５～２００の整数である。）
（Ｂ）下記平均組成式（２）で表されるオルガノポリシロキサン、
Ｒ^３ _ｂＳｉＯ_{（４－ｂ）／２} （２）
（式中、Ｒ^３は、独立に非置換または置換の炭素原子数１～１８の１価炭化水素基であり、ｂは１．８～２．２の数である）、及び
（Ｃ）金属、金属酸化物、金属水酸化物、金属窒化物、金属炭化物、及び炭素の同素体からなる群より選ばれる少なくとも１種の熱伝導性充填剤、
を含有し、
（Ａ）成分及び（Ｂ）成分の合計の配合量が、組成物全体に対し３～９０質量％であり、
（Ｃ）成分の配合量が、組成物全体に対し１０～９７質量％のものであることを特徴とする熱伝導性シリコーン組成物を提供する。 In order to solve the above problems, in the present invention,
(A) an organopolysiloxane represented by the following general formula (1);

(In the formula, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, R ² is a group having an oxirane ring, and X may contain a heteroatom. an alkylene group having 1 to 20 carbon atoms, and a is an integer of 5 to 200.)
(B) an organopolysiloxane represented by the following average composition formula (2);
R ³ _b SiO _(4-b)/2 (2)
(wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms and b is a number from 1.8 to 2.2), and (C) a metal , at least one thermally conductive filler selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbides, and carbon allotropes;
contains
The total amount of component (A) and component (B) is 3 to 90% by mass with respect to the entire composition,
Provided is a thermally conductive silicone composition in which the amount of component (C) is 10 to 97% by mass based on the total composition.

With the thermally conductive silicone composition of the present invention, it is possible to suppress an increase in the viscosity of the composition or an increase in the hardness of the cured product when exposed to high temperatures for a long period of time. Therefore, the reliability of the mounted electronic component package or power module can be improved.

Further, in the present invention, the component (B) has at least two aliphatic unsaturated hydrocarbon groups having 2 to 18 carbon atoms in one molecule, and
(D) Organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule: Hydrogen atoms bonded to silicon atoms relative to the total number of unsaturated aliphatic hydrocarbon groups in component (B) and (E) a platinum group metal catalyst: an effective amount.

In this case, the thermally conductive silicone composition of the present invention becomes addition-curable, and the cured thermally conductive silicone product obtained by curing this addition-curable thermally conductive silicone composition does not react well when exposed to high temperatures for a long period of time. It is possible to suppress the increase in hardness of Therefore, the reliability of the mounted electronic component package or power module can be improved.

The addition curing thermally conductive silicone composition further contains (F) one or more addition curing reaction controllers selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds and organic chloro compounds. It is preferable to contain.

Storage stability and workability can be improved with such an addition-curable thermally conductive silicone composition.

The present invention also provides a cured thermally conductive silicone product, which is a cured product of the addition-curable thermally conductive silicone composition.

The thermally conductive silicone cured product of the present invention exhibits little increase in hardness when exposed to high temperatures for a long period of time, and is effective as a heat dissipation material.

As described above, the thermally conductive silicone composition of the present invention can suppress an increase in the viscosity of the composition when exposed to high temperatures for a long period of time in the case of the non-curable type, and In particular, the cured thermally conductive silicone material obtained from the thermally conductive silicone composition of the present invention exhibits a small increase in hardness when exposed to high temperatures for a long period of time. For this reason, both non-curable and curable thermally conductive silicone compositions are suitable as heat-dissipating materials for use in electronic component packages and power modules that require high reliability.

As a result of intensive studies to achieve the above object, the present inventors have found a thermally conductive polysiloxane containing an organopolysiloxane having an oxirane ring, an organopolysiloxane having a predetermined structure, and a thermally conductive filler in a predetermined ratio. The present inventors have found that a silicone composition can suppress an increase in the viscosity of the composition when exposed to high temperatures for a long period of time and provide a cured product with a small increase in hardness when exposed to high temperatures for a long period of time. came to form

（式中、Ｒ^１は、独立に非置換または置換の炭素原子数１～１８の１価炭化水素基であり、Ｒ^２は、オキシラン環を有する基であり、Ｘは、ヘテロ原子を含んでもよい炭素原子数１～２０のアルキレン基であり、ａは５～２００の整数である。）
（Ｂ）下記平均組成式（２）で表されるオルガノポリシロキサン、
Ｒ^３ _ｂＳｉＯ_{（４－ｂ）／２} （２）
（式中、Ｒ^３は、独立に非置換または置換の炭素原子数１～１８の１価炭化水素基であり、ｂは１．８～２．２の数である）、及び
（Ｃ）金属、金属酸化物、金属水酸化物、金属窒化物、金属炭化物、及び炭素の同素体からなる群より選ばれる少なくとも１種の熱伝導性充填剤、
を含有し、
（Ａ）成分及び（Ｂ）成分の合計の配合量が、組成物全体に対し３～９０質量％であり、
（Ｃ）成分の配合量が、組成物全体に対し１０～９７質量％のものであることを特徴とする熱伝導性シリコーン組成物を提供する。 That is, the present invention provides (A) an organopolysiloxane represented by the following general formula (1),

(In the formula, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, R ² is a group having an oxirane ring, and X may contain a heteroatom. an alkylene group having 1 to 20 carbon atoms, and a is an integer of 5 to 200.)
(B) an organopolysiloxane represented by the following average composition formula (2);
R ³ _b SiO _(4-b)/2 (2)
(wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms and b is a number from 1.8 to 2.2), and (C) a metal , at least one thermally conductive filler selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbides, and carbon allotropes;
contains
The total amount of component (A) and component (B) is 3 to 90% by mass with respect to the entire composition,
Provided is a thermally conductive silicone composition in which the amount of component (C) is 10 to 97% by mass based on the total composition.

Although the present invention will be described in detail below, the present invention is not limited thereto.

Thermally Conductive Silicone Composition The thermally conductive silicone composition of the present invention contains components (A), (B), and (C), which will be described later. The blending amount is 3 to 90% by mass of the entire composition, and the blending amount of component (C) is 10 to 97% by mass of the entire composition. By adjusting the composition and ratio of the above components (A) to (C) and other components added as necessary, this thermally conductive silicone composition can be a non-curable type or a curable type as described later. It can also be a mold.
For example, component (B) has at least two aliphatic unsaturated hydrocarbon groups having 2 to 18 carbon atoms in one molecule, and (D) has two or more silicon atoms in one molecule. Organohydrogenpolysiloxane having bonded hydrogen atoms: an amount such that the number of hydrogen atoms bonded to silicon atoms is 0.5 to 5 relative to the total number of aliphatic unsaturated hydrocarbon groups in component (B), and (E) a platinum group metal catalyst: when it contains an effective amount, it can be an addition-curable thermally conductive silicone composition.
Each component will be described below.

（式中、Ｒ^１は、独立に非置換または置換の炭素原子数１～１８の１価炭化水素基であり、Ｒ^２は、オキシラン環を有する基であり、Ｘは、ヘテロ原子を含んでもよい炭素原子数１～２０のアルキレン基であり、ａは５～２００の整数である。） [(A) component]
Component (A) is an organopolysiloxane having an oxirane ring-containing group (epoxy group) represented by the following general formula (1). It is a component that plays a role in assisting high filling of the thermally conductive filler.

(In the formula, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, R ² is a group having an oxirane ring, and X may contain a heteroatom. an alkylene group having 1 to 20 carbon atoms, and a is an integer of 5 to 200.)

R ¹ is preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms. For example, alkyl groups such as 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; Aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group; substituted with a halogen atom, a cyano group, etc., such as a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, a cyanoethyl group, and the like. A methyl group is particularly preferred.

The above R ¹ is an unsubstituted or substituted monovalent hydrocarbon group, and the silicon atom to which R ¹ is bonded is directly bonded to the carbon atom constituting R ¹ . That is, R ¹ does not become an alkoxy group or an aryloxy group, and is clearly distinguished from these groups.

The group having an oxirane ring for R ² is not particularly limited, but includes oxirane (ethylene oxide) and a group obtained by removing one hydrogen atom from a linear, branched or cyclic hydrocarbon having one or more oxirane rings. . The hydrocarbon may be further substituted with a substituent such as a halogen atom, a cyano group, an aromatic group such as a phenyl group, and the like.
Examples of hydrocarbon groups having such an oxirane ring include epoxyalkanes such as epoxypropane, 1,2-epoxybutane, 2,3-epoxybutane, 3-methyl-1,2-epoxybutane, epoxycyclo epoxycycloalkanes such as pentane, epoxycyclohexane, epoxycycloheptane, epoxycyclooctane, epoxycyclononane, epoxycyclodecane, epoxycycloundecane and epoxycyclododecane; epoxycycloalkenes such as epoxycyclopentene, epoxycyclohexene and epoxycycloheptene; Examples include groups obtained by removing one hydrogen atom from epoxides of aromatic-containing hydrocarbons such as epoxyethylbenzene and 1-phenyl-1,2-epoxypropane.
In addition, the group having an oxirane ring may have two or more oxirane rings in it, and further may be substituted with a heteroatom such as an oxygen atom or a nitrogen atom, or the heteroatom may be a carbon- It may intervene between carbon bonds or between carbon-hydrogen bonds. Examples of groups having such an oxirane ring include glycidyl ethers such as diepoxycyclohexane, epoxycyclohexanol, epoxycyclohexanone, methyl glycidyl ether, ethyl glycidyl ether, ethylene glycol monoglycidyl ether, propanediol monoglycidyl ether, and epoxy piperidine. A group obtained by removing one hydrogen atom from is exemplified.

Examples of the group having an oxirane ring for R ² include those represented by the following formulas (3) and (4).

X is an alkylene group having 1 to 20 carbon atoms which may contain a heteroatom, preferably 1 to 8 carbon atoms, and the structure of X is not particularly limited and may be linear, branched, or the like. is preferably linear. Heteroatoms include an oxygen atom, a nitrogen atom, a sulfur atom, and the like. Examples of X include an alkylene group which may have an ether bond, a thioether bond, an ester group, an amide group, etc. Specific examples thereof include those shown below.

-( _CH2 ) _x-
(x is an integer from 1 to 20.)
_{-CH2CH2CH2OCH2- _ _ _}

The R ² -X group as a whole includes, for example, a 3-glycidoxypropyl group, a 2-(3,4-epoxycyclohexyl)ethyl group, a 5,6-epoxyhexyl group, a 9,10-epoxydecyl group, and the like. .

a is an integer of 5-200, preferably 10-100. If the value of a is less than 5, the component (A) tends to bleed out of the composition, possibly reducing reliability. On the other hand, if it is more than 200, the wettability with the thermally conductive filler may be insufficient.

(A) component can be used individually by 1 type or in combination of 2 or more types as appropriate.

Component (A) is an organopolysiloxane having an oxirane ring represented by the above general formula (1), and the monovalent hydrocarbon group (R ¹ ) bonded to the silicon atom is neither an alkoxy group nor an aryloxy group, It is different from epoxy group-containing silane coupling agents. Epoxy group-containing silane coupling agents require a catalyst because hydrolysis does not proceed with water alone or with water and alcohol. It is possible to treat the surface of the thermally conductive filler without the coexistence of an epoxy ring-opening catalyst. For this reason, the component (A) can sufficiently play a role of assisting high filling of the thermally conductive filler in the composition.

[(B) component]
Component (B) is an organopolysiloxane represented by the following average compositional formula (2), which adjusts the viscosity of the thermally conductive silicone composition of the present invention and imparts tackiness. Moreover, when blending the component (D), which will be described later, it is a component that plays a role as a base oil that forms crosslinks.

R ³ _b SiO _(4-b)/2 (2)
(Wherein, R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, and b is a number of 1.8 to 2.2)

R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, unsubstituted or substituted is a monovalent hydrocarbon group. For example, alkyl groups such as 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; Aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group; substituted with a halogen atom, a cyano group, etc., such as a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, a cyanoethyl group, and the like.

R ³ may also be an aliphatic unsaturated hydrocarbon group having 2 to 18 carbon atoms. The aliphatic unsaturated hydrocarbon group includes alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group and octenyl group.

Among these groups, R ³ is preferably a methyl group or a vinyl group.

b is a number of 1.8 to 2.2, preferably a number of 1.9 to 2.1 from the viewpoint of workability.

The kinematic viscosity of component (B) at 25° C. is not particularly limited, but is preferably 60 to 1,000,000 mm ² /s, more preferably 100 to 100,000 mm ² /s. When the kinematic viscosity is 60 mm ² /s or more, the physical properties of the silicone composition are good, and when it is 1,000,000 mm ² /s or less, the spreadability of the silicone composition is good.
In the present invention, kinematic viscosity is a value at 25° C. measured with an Ostwald viscometer (same below).

The molecular structure of the component (B) is not particularly limited as long as it has the properties described above. . In particular, it preferably has a linear structure in which the main chain consists of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. The organopolysiloxane having a linear structure may partially have a branched structure or a cyclic structure. In addition, the (B) component does not have an oxirane ring (epoxy group). In this respect, the (A) component and the (B) component are clearly distinguished.

(B) component can be used individually by 1 type or in combination of 2 or more types as appropriate.

The total blending amount of components (A) and (B) is 3 to 90% by mass, preferably 7 to 20% by mass, based on the total composition. If it is 90% by mass or less, excellent thermal conductivity will be obtained, and if it is 3% by mass or more, workability will be good. On the other hand, if the content is outside the above range, the thermal conductivity may be insufficient, or the workability may be poor.

[(C) component]
Component (C) is one or more thermally conductive fillers selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon. For example, aluminum, silver, copper, metallic silicon, zinc oxide, magnesium oxide, aluminum oxide (alumina), silicon dioxide, cerium oxide, iron oxide, aluminum hydroxide, cerium hydroxide, aluminum nitride, boron nitride, silicon carbide, diamond , graphite, carbon nanotubes, graphene, and the like. These can be used singly or in combination of two or more, preferably a combination of a large particle component and a small particle component (combination of components having different average particle sizes).

The average particle size of the large particle component is preferably in the range of 0.1 to 300 μm, more preferably in the range of 10 to 200 μm, still more preferably in the range of 10 to 150 μm. The average particle diameter of the small particle component is preferably in the range of 0.01 μm to 10 μm, more preferably 0.1 to 5 μm. Within such a range, the viscosity of the composition does not become too high, the spreadability of the composition is excellent, and the resulting composition is uniform.

The ratio of the large particle component and the small particle component is not particularly limited, and is preferably in the range of 9:1 to 1:9 (mass ratio). Moreover, the shapes of the large particle component and the small particle component are not particularly limited, and may be spherical, irregular, acicular, or the like.

The average particle diameter can be obtained as a volume-based average value (median diameter) in particle size distribution measurement by a laser beam diffraction method, for example.

The amount of component (C) is 10 to 97% by mass, preferably 40 to 95% by mass, more preferably 70 to 90% by mass, based on the total composition. If it is more than 97% by mass, the composition will have poor extensibility, and if it is less than 10% by mass, it will have poor thermal conductivity.

In the thermally conductive silicone composition of the present invention, when the above component (B) has at least two aliphatic unsaturated hydrocarbon groups having 2 to 18 carbon atoms in one molecule, in addition to the above components, By adding the following components (D) and (E) as necessary, an addition-curable thermally conductive silicone composition can be obtained. Hereinafter, such a composition is also referred to as an addition curing thermally conductive silicone composition.

[(D) component]
Component (D) is an organohydrogenpolysiloxane having 2 or more silicon-bonded hydrogen atoms (SiH groups) per molecule, particularly preferably 2 to 100, more preferably 2 to 50. In the organohydrogenpolysiloxane, the SiH groups in the molecule are added in the presence of a platinum group metal catalyst (component (E) described later) when the component (B) has an aliphatic unsaturated hydrocarbon group. Any material can be used as long as it can react (hydrosilylate) to form a crosslinked structure.

The molecular structure of the organohydrogenpolysiloxane is not particularly limited as long as it has the properties described above. structure and the like. A linear structure and a cyclic structure are preferred.

The organohydrogenpolysiloxane has a kinematic viscosity at 25° C. of preferably 1 to 1,000 mm ² /s, more preferably 10 to 300 mm ² /s. If the kinematic viscosity is 1 mm ^{2 /} s or more, the physical properties of the silicone composition may not deteriorate. There is no

Examples of the organic groups bonded to the silicon atoms of the organohydrogenpolysiloxane include unsubstituted or substituted monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups. In particular, it is an unsubstituted or substituted monovalent hydrocarbon radical having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and dodecyl group, aryl groups such as phenyl group, aralkyl groups such as 2-phenylethyl group and 2-phenylpropyl group, these hydrogen Those in which some or all of the atoms are substituted with halogen atoms such as fluorine, bromine, and chlorine, cyano groups, epoxy ring-containing organic groups (glycidyl groups or glycidyloxy group-substituted alkyl groups), etc., such as chloromethyl group and chloropropyl bromoethyl, trifluoropropyl, cyanoethyl, 2-glycidoxyethyl, 3-glycidoxypropyl, and 4-glycidoxybutyl groups. Among these, a methyl group and a 3-glycidoxypropyl group are preferred.

Organohydrogenpolysiloxane having an epoxy ring-containing organic group has SiH groups, and is therefore clearly distinguished from the components (A) and (B), which do not have SiH groups.

The organohydrogenpolysiloxane may be used alone or in combination of two or more.

The amount of component (D) organohydrogenpolysiloxane to be blended is such that the number of SiH groups in component (D) relative to the total number of aliphatic unsaturated hydrocarbon groups in component (B) is 0.5 to 5. , preferably 0.7 to 4.5, more preferably 1 to 4. If the amount of component (D) is at least the above lower limit, the addition reaction will proceed sufficiently to achieve sufficient cross-linking. Moreover, when the content is equal to or less than the above upper limit, the crosslinked structure does not become non-uniform, and the storage stability of the composition is not significantly deteriorated.

[(E) Component]
Component (E) is a platinum group metal catalyst and functions to promote the addition reaction between component (B) having an aliphatic unsaturated hydrocarbon group and component (D). As the platinum group metal catalyst, conventionally known ones used for addition reactions can be used. For example, platinum-based, palladium-based, and rhodium-based catalysts can be used, but platinum or platinum compounds, which are relatively easily available, are preferred. Examples thereof include simple platinum, platinum black, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, and platinum coordination compounds. The platinum group metal catalysts may be used singly or in combination of two or more.

Component (E) may be added in an effective amount as a catalyst, that is, in an effective amount necessary to accelerate the addition reaction and cure the thermally conductive addition-curable silicone composition of the present invention. It is preferably 0.1 to 500 ppm, more preferably 1 to 200 ppm, and still more preferably 10 to 100 ppm based on the mass of platinum group metal atoms, relative to the entire composition. If the amount of the catalyst is at least the above lower limit, the effect as a catalyst can be sufficiently obtained. Moreover, if it is below the said upper limit, it will be economical.

[(F) component]
The addition curable thermally conductive silicone composition of the present invention contains (F) one or more addition curing reaction inhibitors selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds and organic chloro compounds. It is preferable to contain.

Component (F) is a reaction control agent that suppresses the progress of the hydrosilylation reaction at room temperature, and can be added to prolong shelf life and pot life. As the reaction control agent, conventionally known reaction control agents used for addition curing silicone compositions can be used. These include, for example, acetylene compounds such as acetylene alcohols (eg, ethynylmethyldecylcarbinol, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol), tributylamine, tetra Examples include various nitrogen compounds (excluding oxime compounds) such as methylethylenediamine and benzotriazole, organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

When the component (F) is blended, the blending amount is preferably 0.05 to 5 parts by mass, more preferably 0.05 to 5 parts by mass with respect to the total 100 parts by mass of the component (B) having an aliphatic unsaturated hydrocarbon group. It is 0.1 to 2 parts by mass. If the amount of the reaction control agent is 0.05 parts by mass or more, the desired sufficient shelf life and pot life can be obtained, and if it is 5 parts by mass or less, the curability of the silicone composition may decrease There is no

Also, the reaction control agent may be diluted with organo(poly)siloxane, toluene, or the like in order to improve its dispersibility in the silicone composition.

[Other ingredients]
The thermally conductive silicone composition of the present invention may further contain other components different from the components (A) to (F) above, if necessary. For example, hydrolyzable organopolysiloxanes, various modified silicones, and hydrolyzable organosilanes may be blended for the purpose of improving the filling properties of the thermally conductive filler or imparting adhesiveness to the composition. Furthermore, a solvent may be added to adjust the viscosity of the composition. Furthermore, in order to prevent deterioration of the silicone composition, conventionally known antioxidants such as 2,6-di-tert-butyl-4-methylphenol may be contained as necessary. Furthermore, dyes, pigments, flame retardants, anti-settling agents, thixotropic agents, etc. can be blended as needed. The above hydrolyzable organopolysiloxane, modified silicone and hydrolyzable organosilane are different from any of the above components (A), (B) and (D).

Step of Preparing the Silicone Composition The method of preparing the silicone composition of the present invention will now be described. Although the method for producing the silicone composition of the present invention is not particularly limited, the above-described components (A) to (C) and, if necessary, components (D) to (F) and other components may be used. , For example, Trimix, Twinmix, Planetary Mixer (both registered trademarks of mixers manufactured by Inoue Seisakusho Co., Ltd.), Ultra Mixer (registered trademarks of mixers manufactured by Mizuho Industry Co., Ltd.), Hibismix (Primex Co., Ltd. A method of mixing using a mixer or the like such as a registered trademark of a mixer manufactured by the company.

Moreover, the thermally conductive silicone composition of the present invention may be mixed while being heated. The heating conditions are not particularly limited, but the temperature is usually 25 to 220° C., preferably 40 to 200° C., particularly preferably 50 to 170° C., and the time is usually 3 minutes to 24 hours, preferably 5 minutes to 12 hours, particularly preferably 10 minutes to 6 hours. Further, degassing may be performed during heating.

When the components (D) to (F) are mixed, it is preferred that the components (A) to (C) are heated and mixed in advance at 25 to 220° C., and then the components (D) to (F) are mixed. Moreover, degassing may be performed at the time of mixing either or both.

The thermally conductive silicone composition of the present invention has an absolute viscosity measured at 25° C. of preferably 10 to 1,000 Pa·s, more preferably 20 to 700 Pa·s, still more preferably 30 to 500 Pa·s. be. When the absolute viscosity is 10 Pa·s or more, shape retention is facilitated, sedimentation of the thermally conductive filler can be suppressed, and workability is not deteriorated. Further, if the absolute viscosity is 1,000 Pa·s or less, there is no possibility that workability will be deteriorated, such as easy discharge and application. The absolute viscosity can be obtained by adjusting the blending amount of each component described above. The absolute viscosity can be measured at 25° C. using, for example, a Malcolm viscometer (type PC-1T).

Also, the thermally conductive silicone composition of the present invention can generally have a thermal conductivity of 0.5 to 20 W/m·K. Note that the thermal conductivity is a value at 25° C. measured by the hot disk method.

As described above, the thermally conductive silicone composition of the present invention can be made into a non-curable type or a curable type by adjusting the composition of each component and their ratio. A non-curable thermally conductive silicone composition can suppress an increase in viscosity of the composition when exposed to high temperatures for a long period of time. In addition, the curable thermally conductive silicone composition can reduce the increase in hardness when the cured product is exposed to high temperatures for a long period of time.

As described above, even if the thermally conductive silicone composition of the present invention contains a large amount of thermally conductive filler and is mounted on the heat generating part for a long period of time, the viscosity of the composition increases in the case of the non-curing type. In the case of a curable type, the hardness of the cured product does not increase, so the formed thermal conductor does not separate from the heat generating part, and the reliability of electronic component packages and power modules can be sufficiently maintained. .

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The kinematic viscosity is a value at 25° C. measured by an Ostwald viscometer. The average particle diameter is a volume-based average value (median diameter) in particle size distribution measurement by a laser beam diffraction method.

Components (A) to (F) used in the following examples and comparative examples are shown below.

(A) Component A-1: Organopolysiloxane represented by the following formula (5) (kinematic viscosity at 25° C.=35 mm ² /s)

A-2: Organopolysiloxane represented by the following formula (6) (kinematic viscosity at 25° C.=30 mm ² /s)

A-3: Organopolysiloxane represented by the following formula (7) (kinematic viscosity at 25° C.=70 mm ² /s)

A-4 (Comparative Example): Organopolysiloxane represented by the following formula (8) (kinematic viscosity at 25° C.=30 mm ² /s)

(B) Component B-1: Dimethylpolysiloxane having both ends capped with trimethylsilyl groups and a kinematic viscosity of 2,000 mm ² /s at 25°C B-2: Both ends capped with dimethylvinylsilyl groups, 25°C Dimethylpolysiloxane B-3 having a kinematic viscosity of 600 mm ² /s at 25° C.: A dimethylpolysiloxane having both ends blocked with trimethylsilyl groups and having two vinyl groups in the molecular chain and having a kinematic viscosity of 600 mm ² /s at 25° C.

B-4: Dimethylpolysiloxane having both ends blocked with dimethylvinylsilyl groups and a kinematic viscosity at 25°C of 400 mm ² /s B-5: Both ends blocked with dimethylvinylsilyl groups and a kinematic viscosity at 25°C of 30 mm ² /s dimethylpolysiloxane

(C) Component C-1: Aluminum powder with an average particle size of 20 µm: Aluminum powder with an average particle size of 2 µm = 60:40 (mass ratio) C-2: Zinc oxide powder with an average particle size of 0.3 µm C-3 : Aluminum oxide powder with an average particle size of 75 µm: Aluminum oxide powder with an average particle size of 45 µm: Aluminum oxide powder with an average particle size of 10 µm: Aluminum oxide powder with an average particle size of 1 µm = 22:22:22:34 (mass ratio) mixture C-4: A mixture of aluminum nitride powder with an average particle size of 60 µm, aluminum nitride powder with an average particle size of 20 µm, and aluminum nitride powder with an average particle size of 1 µm = 50:20:30 (mass ratio)

(D) Component D-1: Methylhydrogendimethylpolysiloxane represented by the following formula (9) (kinematic viscosity at 25°C = 30 mm ² /s)

D-2: Methylhydrogendimethylpolysiloxane represented by the following formula (10) (kinematic viscosity at 25°C = 40 mm ² /s)

D-3: Methylhydrogendimethylpolysiloxane represented by the following formula (11) (kinematic viscosity at 25°C = 130 mm ² /s)

D-4: Methylhydrogendimethylpolysiloxane represented by the following formula (12) (kinematic viscosity at 25°C = 25 mm ² /s)

(E) Component E-1: A solution of a platinum-divinyltetramethyldisiloxane complex dissolved in the same dimethylpolysiloxane as B-2 above (platinum atom content: 1% by mass)

(F) Component F-1: 1-ethynyl-1-cyclohexanol represented by the following formula (13)

F-2: ethynylmethyldecylcarbinol represented by the following formula (14)

Preparation of Thermally Conductive Silicone Composition Components (A) to (F) above are blended in the amounts shown in Table 1 below, using the method shown below, to form a thermally conductive silicone composition (non-curing type and addition-curing type). ) was prepared.

(Non-curing thermally conductive silicone composition)
[Examples 1 and 2, Comparative Example 1]
Components (A), (B) and (C) were added to a 5-liter planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.) and mixed at 170° C. for 1 hour while being degassed. After cooling to 40° C. or less, the mixture was mixed at 25° C. to prepare a non-curable thermally conductive silicone composition.

(Addition-curable thermally conductive silicone composition)
[Examples 3 to 7, Comparative Examples 2 to 4]
Components (A), (B) and (C) were added to a 5-liter planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.) and mixed at 170° C. for 1 hour while being degassed. After cooling to 40°C or less, components (F), (E) and (D) were added and mixed at 25°C to prepare an addition curing thermally conductive silicone composition. SiH/SiVi is the ratio of the total number of SiH groups in component (D) to the total number of alkenyl groups in component (B).

Table 1 shows the results of measuring the absolute viscosity, thermal conductivity and hardness of the cured product of the resulting composition according to the following methods.

[Absolute viscosity]
The absolute viscosity of each silicone composition was measured at 25° C. using a Malcolm viscometer (type PC-1T) (rotor A, 10 rpm, shear rate 6 [1/s]).
In addition, the non-curable thermally conductive silicone compositions of Examples 1 and 2 and Comparative Example 1 were filled in a 100 ml glass beaker and exposed to an environment of 150° C. for 250 hours before measuring the absolute viscosity. bottom.

[Thermal conductivity]
Each composition was wrapped in kitchen wrap, and thermal conductivity was measured by the hot disk method (ISO 22007-2) using TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd.

[hardness]
The addition-curable thermally conductive silicone compositions of Examples 3 to 7 and Comparative Examples 2 to 4 were cured by heating at 150°C for 1 hour. The hardness before and after exposure to the environment for 250 hours was measured using an Asker C hardness tester.

From the results in Table 1, the thermally conductive silicone compositions of Examples 1 to 7 (Examples 1 and 2 are non-curing types, Examples 3-7 are addition-curing types) satisfying the requirements of the present invention show that a large amount of heat It can be seen that the increase in viscosity or hardness after being held at 150° C. for 250 hours is small, even though the addition of the conductive filler results in high thermal conductivity. That is, high reliability can be obtained when electronic component packages or power modules are mounted.

On the other hand, in the thermally conductive silicone compositions of Comparative Examples 1 to 4, which did not contain components (A-1) to (A-3) (component (A) of the present invention), the viscosity after holding at 150°C for 250 hours was It can be seen that the increase in hardness is large. That is, there is a possibility that the reliability at the time of electronic component package or power module mounting is lowered.

Therefore, the thermally conductive silicone composition of the present invention, in the case of the non-curing type, can suppress the viscosity increase of the composition even when exposed to high temperatures for a long period of time, and in the case of the curable type, it is possible to suppress the increase in viscosity even when exposed to high temperatures. Even if it is exposed for a long time, it is possible to suppress the increase in hardness of the cured product. Due to such properties, it can be particularly suitably used as a heat dissipation grease for use in electronic component packages and power modules that require high reliability.

It should be noted that the present invention is not limited to the above embodiments. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

Claims (4)

(A) an organopolysiloxane represented by the following general formula (1);

(In the formula, R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, R ² is a group having an oxirane ring, and X may contain a heteroatom. an alkylene group having 1 to 20 carbon atoms, and a is an integer of 5 to 200.)
(B) an organopolysiloxane represented by the following average composition formula (2);
R ³ _b SiO _(4-b)/2 (2)
(wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms and b is a number from 1.8 to 2.2), and (C) a metal , at least one thermally conductive filler selected from the group consisting of metal oxides, metal hydroxides, metal nitrides, metal carbides, and carbon allotropes;
contains
The total amount of component (A) and component (B) is 3 to 90% by mass with respect to the entire composition,
A thermally conductive silicone composition, wherein component (C) is contained in an amount of 10 to 97% by mass based on the total composition. The component (B) has at least two aliphatic unsaturated hydrocarbon groups having 2 to 18 carbon atoms in one molecule, and
(D) Organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms in one molecule: Hydrogen atoms bonded to silicon atoms relative to the total number of unsaturated aliphatic hydrocarbon groups in component (B) 2. The thermally conductive silicone composition according to claim 1, comprising an amount such that the number of atoms is 0.5 to 5, and (E) a platinum group metal catalyst: an effective amount. 3. The composition according to claim 2, further comprising (F) one or more addition curing reaction inhibitors selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds and organic chloro compounds. A thermally conductive silicone composition. A cured thermally conductive silicone product, which is a cured product of the thermally conductive silicone composition according to claim 2 or 3.