Thermally-conductive addition hardening type silicone composition

Abstract

To provide a thermally conductive addition hardening type silicone composition giving a hardened product low in a storage elastic modulus G' and high in extension when thermally hardened.SOLUTION: A thermally conductive addition hardening type silicone composition includes: (A) an organopolysiloxane having at least one alkynyl group in a molecule, and a kinetic viscosity at 25°C of 60 to 100,000 nm2 / s; (B) at least one thermally-conductive filler selected from the group consisting of a metal, a metal oxide, a metal hydroxide, a metal nitride, a metal carbide, and a carbon allotrope; (C) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule; (D) a platinum group metal catalyst; and (E) one or more addition hardening reaction control agents selected from the group consisting of an acetylenic compound, a nitrogen compound, an organic phosphorous compound, an oxime compound, and an organic chloro compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermally conductive addition-curing silicone composition.

Background Art

[0002] As a common problem in electronic component packages and power modules, heat generation during operation and the resulting performance degradation are widely known, and various heat dissipation techniques are used as means to solve this problem. In particular, a technique of arranging a cooling member near the heat generating part and bringing the two into close contact, and then efficiently removing heat from the cooling member to dissipate heat is common.

[0003] At this time, if there is a gap between the heat generating part and the cooling member, the heat transfer coefficient will decrease due to the presence of air with poor thermal conductivity, and the temperature of the heat generating member will not drop sufficiently. In order to prevent the presence of such air and improve heat conduction, a heat dissipation material with good thermal conductivity and followability on the surface of the member, such as heat dissipation grease or a heat dissipation sheet, is used.

[0004] As a practical heat countermeasure for electronic component packages and power modules, heat dissipation grease that is thin, compressible, and has excellent invasiveness into the gap between the heat generating part and the cooling member is suitable from the viewpoint of heat dissipation performance. Furthermore, by heat-curing after compression to a desired thickness, it is difficult to generate the outflow (pumping out) of the heat dissipation grease due to the expansion and contraction caused by the heat history of repeated heat generation and cooling of the heat generating part, and an addition-curing type heat dissipation grease that can enhance the reliability of electronic component packages and power modules is particularly useful (for example, Patent Document 1).

[0005] In recent years, with the progress of the large-area development and the complexity of the structure of electronic component packages and power modules, very large warpage may occur in electronic component packages and power modules. In electronic component packages and power modules with large warpage, an addition-curing type heat-dissipating grease that cures softly and has a low storage elastic modulus G' of the cured product, that is, a cured product that follows the warpage, is often used. On the other hand, in order to follow the expansion and contraction due to the heat history of repeatedly heating and cooling the heat-generating part over a long period of time, an addition-curing type heat-dissipating grease that provides a highly extensible cured product is effective. Generally, an addition-curing type heat-dissipating grease with a low storage elastic modulus G' of the cured product becomes a cured product close to a paste shape, so it is difficult to become a highly extensible cured product. Also, an addition-curing type heat-dissipating grease that provides a highly extensible cured product becomes a cured product with high hardness and high strength.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a thermally conductive addition-curing type silicone composition that gives a cured product having a low storage elastic modulus G' and a high elongation when heat-cured.

Means for Solving the Problems

[0008] In order to solve the above problems, the present invention is a thermally conductive addition-curing type silicone composition, (A) An organopolysiloxane having at least one alkynyl group in one molecule and a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s, (B) At least one thermally conductive filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon: an amount that is 10 to 96% by mass based on the entire composition, (C) Organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule: an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of alkynyl groups in component (A). (D) Platinum group metal catalyst: an effective amount (E) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds: 0.05 to 5 parts by mass with respect to 100 parts by mass of component (A). Provided is a thermally conductive addition-curing silicone composition characterized by containing the above components.

[0009] The thermally conductive addition-curing silicone composition of the present invention gives a cured product having a low storage modulus G' and high elongation when heat-cured.

[0010] The thermally conductive addition-curing silicone composition of the present invention preferably contains, as component (F), an organopolysiloxane represented by the following general formula (1) in an amount of 0.5 to 10% by mass based on the whole silicone composition.

Chemical formula

[0011] In such a thermally conductive addition-curing silicone composition of the present invention, the above component (F) is used to treat the surface of the thermally conductive filler and plays a role in assisting the high loading of the filler.

[0012] Furthermore, the thermally conductive addition-curing silicone composition of the present invention preferably contains, as component (G), an organosilane represented by the following general formula (2) and / or its (partial) hydrolysis condensate in an amount of 0.1 to 10% by mass based on the total amount of the silicone composition. R 2 a Si(OR 3 ) 4-a (2) (R 2 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R 3 is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is an integer of 1 to 3.)

[0013] In such a thermally conductive addition-curing silicone composition of the present invention, the component (G) is used for treating the surface of the thermally conductive filler and plays a role in assisting the high loading of the filler.

[0014] The thermally conductive addition-curing silicone composition of the present invention preferably has, as component (A), an organopolysiloxane having at least two alkynyl groups in one molecule.

[0015] Furthermore, the thermally conductive addition-curing silicone composition of the present invention preferably has, as component (A), an organopolysiloxane having at least two ethynyl groups in one molecule.

[0016] Such a thermally conductive addition-curing silicone composition of the present invention gives a cured product having a low storage modulus G' and high elongation when heat-cured.

Advantages of the Invention

[0017] As described above, the thermally conductive addition-curing silicone composition of the present invention gives a cured product having a low storage modulus G' and high elongation when heat-cured. As a result, it can be suitably used for electronic component packages and power modules with large warpage, and can also follow the expansion and contraction due to the heat history of repeatedly generating heat and cooling the heat-generating part over a long period of time.

Mode for Carrying Out the Invention

[0018] As described above, there has been a demand for the development of a thermally conductive addition-curing silicone composition that gives a cured product having a low storage elastic modulus G' and high elongation.

[0019] As a result of intensive studies on the above problems, the present inventors have found that a thermally conductive addition-curing silicone composition containing the above components (A) to (E) can give a cured product having a low storage elastic modulus G' and high elongation, and have completed the present invention.

[0020] That is, the present invention is a thermally conductive addition-curing silicone composition comprising: (A) An organopolysiloxane having at least one alkynyl group in one molecule and having a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s; (B) At least one thermally conductive filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon: in an amount of 10 to 96% by mass based on the whole composition; (C) An organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule: in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of alkynyl groups in component (A); (D) A platinum group metal catalyst: in an effective amount; (E) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chlorine compounds: 0.05 to 5 parts by mass with respect to 100 parts by mass of component (A). The thermally conductive addition-curing silicone composition is characterized by containing the above components.

[0021] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0022] [Component (A)] (A) component has at least 1, preferably 1 to 100, more preferably 2 to 50 alkynyl groups in one molecule, and has a kinematic viscosity at 25 °C of 60 to 100,000 mm 2 / s and is an organopolysiloxane.

[0023] The alkynyl group is preferably a monovalent hydrocarbon group having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and having a carbon-carbon triple bond. For example, terminal alkynes such as ethynyl group and propargyl group, and internal alkynes having a group other than a hydrogen atom on the carbon atom forming the carbon-carbon triple bond can be mentioned. Terminal alkynes are preferred, and ethynyl group is more preferred.

[0024] The alkynyl group may be bonded to either the silicon atom at the end of the molecular chain or the silicon atom in the middle of the molecular chain, or may be bonded to both.

[0025] As the organic group other than the alkynyl group bonded to the silicon atom of the above organopolysiloxane, it is 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. 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, naphthyl group; aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, or those in which a part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, or cyano group, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, etc. Particularly, methyl group and phenyl group are preferred.

[0026] The above organopolysiloxane has a kinematic viscosity at 25 °C of 60 to 100,000 mm 2 / s, preferably 100 to 30,000 mm 2 / s is. The kinematic viscosity is 60 mm 2If it is less than / s, the physical properties of the thermally conductive addition-curing silicone composition of the present invention will deteriorate, and when it exceeds 100,000 mm 2 / s, the stretchability of the silicone composition will be poor.

[0027] In the present invention, the kinematic viscosity is the value at 25 °C measured by an Ubbelohde-type Ostwald viscometer (hereinafter the same).

[0028] The molecular structure of the above organopolysiloxane is not particularly limited as long as it has the above properties, and examples include a linear structure, a branched-chain structure, a partially branched structure, or a linear structure having a cyclic structure. In particular, those having a linear structure in which the main chain is composed of repeating units of diorganosiloxane and both ends of the molecular chain are blocked with triorganosiloxy groups are preferred. The organopolysiloxane having a linear structure may partially have a branched structure or a cyclic structure.

[0029] The blending amount of the component (A) is preferably 1.5 to 90% by mass, more preferably 1.7 to 20% by mass, and still more preferably 1.8 to 10% by mass with respect to the entire thermally conductive silicone composition of the present invention. If it is in the range of 1.5 to 90% by mass, the thermally conductive addition-curing silicone composition of the present invention will have sufficient thermal conductivity, appropriate viscosity increase, and excellent workability.

[0030] The above organopolysiloxane can be used alone or in combination of two or more.

[0031] [Component (B)] (Component (B) 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 can be mentioned. These can be used alone or in appropriate combination of two or more, and it is preferable that they are a combination of a large particle component and a small particle component (a combination of components having different average particle diameters).

[0032] The average particle diameter of the large particle component is preferably in the range of 0.1 to 300 μm, more preferably in the range of 5 to 200 μm, and 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. If it is in such a range, the thermally conductive addition-curing silicone composition of the present invention will have an appropriate viscosity, excellent stretchability, and the resulting silicone composition will be uniform.

[0033] The ratio of the large particle component to the small particle component is not particularly limited, and a range of 9:1 to 1:9 (mass ratio) is preferable. Also, the shapes of the large particle component and the small particle component are spherical, irregular, needle-like, etc., and are not particularly limited.

[0034] Note that the average particle diameter can be determined, for example, as the volume-based average value (median diameter) in the particle size distribution measurement by the laser light diffraction method.

[0035] (The blending amount of component (B) is 10 to 96% by mass based on the whole thermally conductive addition-curing silicone composition of the present invention, preferably 40 to 95.5% by mass, more preferably 70 to 95% by mass, and still more preferably 85 to 93% by mass. If it is more than 96% by mass, the silicone composition will have poor stretchability, and if it is less than 10% by mass, it will have poor thermal conductivity.

[0036] [Component (C)] Component (C) is an organohydrogenpolysiloxane having, in one molecule, two or more, preferably 2 to 100, more preferably 2 to 50 hydrogen atoms (Si-H groups) bonded to silicon atoms. The organohydrogenpolysiloxane may be any one as long as the Si-H groups in the molecule can undergo an addition reaction with the aliphatic unsaturated hydrocarbon groups of Component (A) described above in the presence of a platinum group metal catalyst to form a crosslinked structure.

[0037] The molecular structure of the above organohydrogenpolysiloxane is not particularly limited as long as it has the above properties, and examples include a linear structure, a branched-chain structure, a cyclic structure, and a linear structure having a partially branched or cyclic structure. Preferred are a linear structure and a cyclic structure.

[0038] The kinematic viscosity of the above organohydrogenpolysiloxane at 25°C is 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 thermally conductive addition-curable silicone composition of the present invention will be appropriate, and if it is 1,000 mm 2 / s or less, the silicone composition will have sufficient extensibility.

[0039] Examples of the organic group bonded to the silicon atom of the organohydrogenpolysiloxane include unsubstituted or substituted monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups. They are unsubstituted or substituted monovalent hydrocarbon groups 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, dodecyl group, aryl groups such as phenyl group, aralkyl groups such as 2-phenylethyl group, 2-phenylpropyl group, and those obtained by substituting part or all of the hydrogen atoms thereof with halogen atoms such as fluorine, bromine, chlorine, cyano group, epoxy ring-containing organic groups (glycidyl group or glycidyloxy group-substituted alkyl group), etc. Examples include chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, 2-glycidoxyethyl group, 3-glycidoxypropyl group, and 4-glycidoxybutyl group. Among these, a methyl group and a phenyl group are preferred.

[0040] The above organohydrogenpolysiloxane may be used alone or in combination of two or more.

[0041] The blending amount of the organohydrogenpolysiloxane as the component (C) is an effective amount sufficient for the thermally conductive silicone composition of the present invention to form a cured product, and the number of Si-H groups in the component (C) relative to the total number of alkynyl groups in the component (A) is 0.5 to 10, preferably 0.7 to 7.5, more preferably 0.9 to 5.0. When the amount of the component (C) is less than 0.5, the addition reaction does not proceed sufficiently and the crosslinking becomes insufficient. On the other hand, when the amount exceeds 10, the crosslinked structure becomes non-uniform and the storage stability of the composition may deteriorate significantly.

[0042] [Component (D)] (D) component is a platinum group metal catalyst. It functions to promote the addition reaction of the above-described components. As the platinum group metal catalyst, a conventionally known one used in the addition reaction can be used. For example, platinum-based, palladium-based, and rhodium-based catalysts can be mentioned, and among them, platinum or a platinum compound that is relatively easily available is preferable. Specifically, simple platinum, platinum black, chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, and platinum coordination compound, etc. can be mentioned. The platinum group metal catalyst may be used alone or in combination of two or more kinds.

[0043] (D) The blending amount of the component is an effective amount as a catalyst, that is, an effective amount necessary to promote the addition reaction and cure the thermally conductive addition-curable silicone composition of the present invention. Preferably, it is 0.01 to 10 ppm, more preferably 0.1 to 5 ppm, and still more preferably 0.2 to 3 ppm on a mass basis converted to platinum group metal atoms with respect to the whole thermally conductive silicone composition of the present invention. When the amount of the catalyst is in the range of 0.01 to 10 ppm, the effect as a catalyst can be sufficiently obtained and it is economical. Also, the storage stability at 25°C is sufficient.

[0044] Also, the catalyst of (D) component may be diluted with organo(poly)siloxane, toluene, etc. and used in order to improve the dispersibility in the thermally conductive addition-curable silicone composition.

[0045] [Component (E)] (E) component is at least one addition-curing reaction controller selected from the group consisting of an acetylene compound, a nitrogen compound, an organophosphorus compound, an oxime compound, and an organic chloro compound. (E) component is an addition-curing reaction controller that suppresses the progress of the hydrosilylation reaction at room temperature, and can be added to extend the shelf life and pot life. As the addition-curing reaction controller, a conventionally known reaction controller used in a thermally conductive addition-curing silicone composition can be used. Examples thereof include acetylene compounds such as acetylene alcohols (for example, ethynyl methyl decyl carbinol, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyne-3-ol), various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole, organophosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

[0046] (E) The compounding amount of the component may be an effective amount as an addition-curing reaction controller, that is, an effective amount necessary to obtain a desired shelf life and pot life. It is 0.05 to 5 parts by mass, preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the component (A). If the amount of the addition-curing reaction controller is less than 0.05 part by mass, there is a possibility that a sufficient desired shelf life and pot life cannot be obtained. If it is more than 5 parts by mass, the curability of the thermally conductive addition-curing silicone composition of the present invention may decrease.

[0047] Also, the addition-curing reaction controller may be diluted with an organo(poly)siloxane, toluene, etc. for better dispersibility in the thermally conductive addition-curing silicone composition of the present invention before use.

[0048] In addition to the above components (A) to (E), the thermally conductive addition-curing silicone composition of the present invention can further add the following optional components as necessary.

[0049] [(F) component] (F) component is an organopolysiloxane represented by the following general formula (1). It is used to treat the surface of the thermal conductivity filler and plays a role in assisting the high filling of the filler. [Chemical formula] (In the formula, R 1 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group without an aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.)

[0050] In the above formula (1), R 1 is a monovalent hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, preferably a monovalent saturated aliphatic hydrocarbon group which may have a substituent, a monovalent aromatic hydrocarbon group which may have a substituent, and more preferably a monovalent saturated aliphatic hydrocarbon group which may have a substituent.

[0051] Specific examples of the monovalent saturated aliphatic hydrocarbon group which may have a substituent include linear alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, etc., branched-chain alkyl groups such as isopropyl group, isobutyl group, tert-butyl group, isopentyl group, neopentyl group, etc., cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, etc., and halogen-substituted alkyl groups such as chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, bromopropyl group, etc. The number of carbon atoms is preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably 1 to 6 carbon atoms.

[0052] Examples of the monovalent aromatic hydrocarbon group which may have a substituent include monovalent aromatic hydrocarbon groups such as aryl groups like phenyl group and tolyl group, aralkyl groups like benzyl group and 2-phenylethyl group, and halogen-substituted aryl groups like α,α,α-trifluorotolyl group and chlorobenzyl group. The number of carbon atoms is preferably 6 to 10, more preferably 6 to 8, and still more preferably 6.

[0053] In the above formula (1), R 1 Among these, a methyl group, an ethyl group, a 3,3,3-trifluoropropyl group, and a phenyl group are preferable, a methyl group, an ethyl group, and a phenyl group are more preferable, and a methyl group is particularly preferable.

[0054] In the above formula (1), m is an integer of 5 to 100, preferably 5 to 80, and more preferably 10 to 60. When the value of m is 5 or more, oil bleeding derived from the silicone composition is suppressed and the pump-out resistance is improved. When the value of m is 100 or less, the wettability with the filler becomes sufficient, the viscosity of the thermally conductive silicone composition of the present invention becomes appropriate, and the coating workability becomes good.

[0055] The blending amount of the component (F) is preferably 0.5 to 10% by mass, more preferably 1.0 to 8.0% by mass, based on the whole thermally conductive silicone composition of the present invention. If it is in the range of 0.5 to 10% by mass, the silicone composition can be set to an appropriate viscosity range.

[0056] The component (F) may be used alone or in combination of two or more.

[0057] [Component (G)] The component (G) is an organosilane represented by the following general formula (2) and / or its (partial) hydrolysis condensate (partial hydrolysis condensate, hydrolysis condensate). R 2 a Si(OR 3 ) 4-a (2) (R2 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R 3 is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is an integer of 1 to 3.)

[0058] (Component (G) is used for treating the surface of the heat conductive filler and plays a role in assisting the high filling of the filler.)

[0059] In the above formula (2), R 2 Examples include an alkyl group, a cycloalkyl group, and an alkenyl group. Specific examples thereof include, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, an alkenyl group such as a vinyl group and an allyl group, an aryl group such as a phenyl group and a tolyl group, an aralkyl group such as a 2-phenylethyl group and a 2-methyl-2-phenylethyl group, and a halogenated hydrocarbon group such as a 3,3,3-trifluoropropyl group, a 2-(perfluorobutyl)ethyl group, a 2-(perfluorooctyl)ethyl group, and a p-chlorophenyl group.)

[0060] In the above formula (2), a is 1, 2 or 3, and particularly preferably 1.)

[0061] In the above formula (2), R 3 Examples include a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)

[0062] (The blending amount of component (G) is preferably 0.1 to 10% by mass, more preferably 0.5 to 5.0% by mass based on the whole heat conductive silicone composition of the present invention. If it is in the range of 0.1 to 10% by mass, the heat conductive silicone composition can be made into an appropriate viscosity range.)

[0063] (Component (G) may be used alone or in combination of two or more.)

[0064] [Other Components] The heat-conductive addition-curing silicone composition of the present invention may contain a non-reactive organo(poly)siloxane such as methylpolysiloxane in order to adjust the strength and viscosity of the silicone composition. Further, the heat-conductive addition-curing silicone composition of the present invention may be blended with a hydrolyzable organopolysiloxane, various modified silicones, or a hydrolyzable organosilane for the purpose of imparting adhesiveness to the silicone composition. Further, a solvent for adjusting the viscosity of the silicone composition may be blended. Further, in order to prevent deterioration of the silicone composition, a conventionally known antioxidant such as 2,6-di-tert-butyl-4-methylphenol may be contained as necessary. Further, dyes, pigments, flame retardants, anti-settling agents, or thixotropy improvers, etc. can be blended as necessary.

[0065] [Process for producing heat-conductive addition-curing silicone composition] The manufacturing method of the heat-conductive addition-curing silicone composition in the present invention will be described. The manufacturing method of the heat-conductive addition-curing silicone composition in the present invention is not particularly limited, but the above components (A) to (E), and, if necessary, in addition to this, component (F), component (G), and / or other components are mixed to produce a heat-conductive addition-curing silicone composition.

[0066] Specifically, the above-described components (A) to (E), and, if necessary, in addition to this, component (F), component (G), and / or other components are, for example, mixed using a mixer such as a trimix, twin mix, planetary mixer (all are registered trademarks of mixers manufactured by Inoue Manufacturing Co., Ltd.), an ultra mixer (a registered trademark of a mixer manufactured by Mizuhou Industry Co., Ltd.), a high bis mix (a registered trademark of a mixer manufactured by Primix Corporation), etc. at 25°C for usually 3 minutes to 24 hours, preferably 5 minutes to 12 hours, more preferably 10 minutes to 6 hours. Also, degassing may be performed during mixing, or mixing may be performed while heating in the range of 40 to 200°C.

[0067] In the present invention, it is preferable from the viewpoint of the thermally conductive addition-curing silicone composition exhibiting good thermal conductivity and appropriate viscosity that the components (A) and (B) are mixed in advance at 50 to 200 °C, and then the components (C), (D), and (E) are mixed at 25 °C.

[0068] The viscosity of the thermally conductive addition-curing silicone composition of the present invention, measured at 25 °C, is preferably 10 to 1,000 Pa·s, more preferably 20 to 700 Pa·s, and even more preferably 40 to 500 Pa·s. If the viscosity is in the range of 10 to 1,000 Pa·s, the thermally conductive addition-curing silicone composition of the present invention is easy to maintain its shape, the thermally conductive filler becomes uniform in the silicone composition, and it is also easy to discharge and apply, resulting in excellent workability. The viscosity can be obtained by adjusting the blending amounts of the above-described respective components.

[0069] In the present invention, the viscosity is a value measured at 25 °C using a Malcolm viscometer (type PC-1T) for the absolute viscosity of the thermally conductive addition-curing silicone composition (10 rpm with rotor A, shear rate 6 [1 / s]).

[0070] Moreover, the thermally conductive addition-curing silicone composition of the present invention usually has a thermal conductivity of 0.5 to 100 W / m·K, but preferably has a thermal conductivity of 2.5 W / m·K or more in order to exhibit excellent heat dissipation performance when mounted on an electronic component package or a power module.

[0071] In the present invention, the thermal conductivity is a value measured with a TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd. by wrapping each thermally conductive addition-curing silicone composition with kitchen wrap.

[0072] The curing conditions when the thermally conductive addition-curing silicone composition of the present invention is heat-cured are not particularly limited, but are usually 80 to 200 °C, preferably 100 to 180 °C, for 15 minutes to 4 hours, preferably 30 minutes to 2 hours.

Examples

[0073] EXAMPLES The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

[0074] First, the following components were prepared for use in preparing the thermally conductive addition-curable silicone composition of the present invention: The kinematic viscosity is the value measured at 25°C using an Ubbelohde-Ostwald viscometer.

[0075] [Component (A)] A-1: Both ends are blocked with dimethylethynyl groups, and the kinematic viscosity at 25°C is 850mm 2 / s dimethylpolysiloxane (Ethynyl group amount = 0.00013 mol / g) A-2: Both ends are blocked with dimethylethynyl groups, and the kinematic viscosity at 25°C is 4,000mm 2 / s dimethylpolysiloxane (Amount of ethynyl groups = 0.000067 mol / g) A-3: Both ends are blocked with dimethylethynyl groups, and the kinematic viscosity at 25°C is 16,000mm 2 / s dimethylpolysiloxane (Amount of ethynyl groups = 0.000045 mol / g) a-4: Both ends are blocked with dimethylvinylsilyl groups, and the kinematic viscosity at 25°C is 1,000mm 2 / s dimethylpolysiloxane (vinyl group amount = 0.00010 mol / g) a-5: Both ends are blocked with dimethylvinylsilyl groups, and the kinematic viscosity at 25°C is 5,000mm 2 / s dimethylpolysiloxane (Amount of vinyl group = 0.000064 mol / g)

[0076] [(B) Component] B-1: Spherical aluminum powder with an average particle size of 12 μm B-2: Spherical aluminum powder with an average particle size of 9 μm B-3: Irregularly shaped zinc oxide powder with an average particle size of 0.4 μm

[0077] [Component (C)] · C-1: Methylhydrogen dimethyl polysiloxane represented by the following formula (3) (Si-H content = 0.00127 mol / g) [Chemical formula] · C-2: Methylhydrogen dimethyl polysiloxane represented by the following formula (4) (Si-H content = 0.00126 mol / g) [Chemical formula] · C-3: Methylhydrogen dimethyl polysiloxane represented by the following formula (5) (Si-H content = 0.00190 mol / g) [Chemical formula]

[0078] [Component (D)] · D-1: Solution prepared by dissolving a platinum-divinyltetramethyldisiloxane complex in the same dimethyl polysiloxane as A-4 above (platinum atom content: 1% by mass)

[0079] [Component (E)] · E-1: 1-Ethynyl-1-cyclohexanol represented by the following formula (6) [Chemical formula]

[0080] [Component (F)] · F-1: One-terminal trimethoxysilyl group-blocked dimethyl polysiloxane represented by the following formula (7) [Chemical formula]

[0081] [Component (G)] · G-1: Organosilane represented by the following formula (8) [Chemical formula]

[0082] [Examples 1 - 5, Comparative Examples 1 - 7] [Preparation of Thermally Conductive Addition - Curing Silicone Composition] The components (A) - (G) were compounded in the compounding amounts shown in Tables 1 and 2 below by the method shown below to prepare a thermally conductive addition - curing silicone composition. In Tables 1 and 2, SiH / SiE is the ratio of the total number of SiH groups in component (C) to the total number of ethynyl groups in component (A), and SiH / SiVi is the ratio of the total number of SiH groups in component (C) to the total number of vinyl groups in component (A).

[0083] Component (A) and (B) were added to a 5 - liter planetary mixer (manufactured by Inoue Manufacturing Co., Ltd.), and then component (F) or (G) was added. When component (F) was added, it was mixed at 170°C for 1 hour, and when component (G) was added, it was mixed at 70°C for 1 hour. After mixing, it was cooled to 40°C or lower, and then components (C), (D), and (E) were added and mixed until homogeneous to prepare a thermally conductive addition - curing silicone composition.

[0084] For each of the thermally conductive addition - curing silicone compositions obtained by the above method, viscosity, thermal conductivity, storage modulus G', and elongation at break were measured according to the following methods. The results are shown in the evaluation results of Tables 1 and 2.

[0085] [Viscosity] The absolute viscosity of each thermally conductive addition - curing silicone composition was measured at 25°C using a Malcolm viscometer (type PC - 1T) (rotor A, 10 rpm, shear rate 6 [1 / s]). [Thermal Conductivity] Each thermally conductive addition - curing silicone composition was wrapped with kitchen wrap, and the thermal conductivity was measured using a TPS - 2500S manufactured by Kyoto Electronics Industry Co., Ltd. [Storage Modulus G'] Between two parallel plates with a diameter of 2.5 cm, each thermally conductive addition-curing silicone composition was applied with a thickness of 2 mm. After heating the applied plates from 25 °C to 150 °C at a rate of 5 °C / min, a program was created to maintain them at 150 °C for 7,200 seconds, and the storage modulus G' 5,100 seconds after the start of the test was read. For the measurement, a viscoelasticity measuring device (ARES-G2: manufactured by TA Instruments) was used. [Elongation at break] After each thermally conductive addition-curing silicone composition was heated and cured at 150 °C for 60 minutes to produce a 2-mm-thick sheet, a dumbbell No. 2 shape was produced in accordance with JIS K6251, and the elongation at break was measured.

[0086]

Table 1

[0087]

Table 2

[0088] From the evaluation results in Tables 1 and 2, it was found that the thermally conductive addition-curing silicone compositions of Examples 1 to 5 that satisfy the requirements of the present invention give a cured product with a low storage modulus G' and high elongation when heat-cured. On the other hand, in the thermally conductive addition-curing silicone compositions of Comparative Examples 1 to 7 prepared using the (a-4) or (a-5) component as the (A) component, although the storage modulus G' when heat-cured was low, the cured product became paste-like and the elongation at break could not be measured.

[0089] Therefore, the thermally conductive addition-curing silicone composition of the present invention gives a cured product with a low storage modulus G' and high elongation when heat-cured. As a result, it can be suitably used for electronic component packages and power modules with large warpage, and can also follow the expansion and contraction due to the heat history of repeated heat generation and cooling of the heat-generating part over a long period of time.

[0090] This specification includes the following aspects. [1]: A heat-conductive addition-curing silicone composition, comprising: (A) An organopolysiloxane having at least one alkynyl group in one molecule and having a kinematic viscosity at 25 °C of 60 to 100,000 mm 2 / s; (B) 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, in an amount of 10 to 96% by mass based on the total composition; (C) An organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule, in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of alkynyl groups in component (A); (D) A platinum group metal catalyst: in an effective amount (E) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds, in an amount of 0.05 to 5 parts by mass with respect to 100 parts by mass of component (A). The heat-conductive addition-curing silicone composition is characterized by containing the above components. [2]: Further, (F) an organopolysiloxane represented by the following general formula (1), in an amount of 0.5 to 10% by mass based on the total composition; [Chemical formula] (In the formula, R 1 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group having no aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.) The heat-conductive addition-curing silicone composition according to [1], characterized by containing the above component. [3]: Further, (G) an organosilane represented by the following general formula (2) and / or its (partial) hydrolysis condensate, in an amount of 0.1 to 10% by mass based on the total composition; R 2 a Si(OR 3 ) 4-a (2) (R 2 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R 3 is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is an integer of 1 to 3.) The thermally conductive addition-curing silicone composition according to [1] or [2], characterized by containing [4]: The thermally conductive addition-curing silicone composition according to [1], [2] or [3], characterized in that the component (A) is an organopolysiloxane having at least two alkynyl groups in one molecule. [5]: The thermally conductive addition-curing silicone composition according to any one of [1] to [4], characterized in that the component (A) is an organopolysiloxane having at least two ethynyl groups in one molecule.

[0091] Note that the present invention is not limited to the above embodiments. The above embodiments are illustrative, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Claims

1. A heat-conductive addition-curing silicone composition, comprising: (A) An organopolysiloxane having at least one alkynyl group in one molecule and having a kinematic viscosity at 25 °C of 60 to 100,000 mm 2 / s, (B)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: in an amount of 10 to 96% by mass based on the total composition; (C)An organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule: in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 relative to the total number of alkynyl groups in component (A); (D)A platinum group metal catalyst: in an effective amount (E)One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds: 0.05 to 5 parts by mass based on 100 parts by mass of component (A) A heat-conductive addition-curing silicone composition, characterized by containing the above components.

2. Furthermore, (F) an organopolysiloxane represented by the following general formula (1): in an amount of 0.5 to 10% by mass based on the total composition; 【Chemical 1】 (wherein R 1 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, which may have a substituent and does not have an aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.) A heat-conductive addition-curing silicone composition according to Claim 1, characterized by containing the above components.

3. Furthermore, (G) an organosilane represented by the following general formula (2) and / or its (partial) hydrolysis condensate: in an amount of 0.1 to 10% by mass based on the total composition; R ２ ａ Si(OR ３ ) ４－ａ (2) (R ２ is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ３ is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a is an integer of 1 to 3.) A heat-conductive addition-curing silicone composition according to Claim 1, characterized by containing the above components.

4. The heat-conductive addition-curing silicone composition according to Claim 1, wherein component (A) is an organopolysiloxane having at least two alkynyl groups in one molecule.

5. The heat-conductive addition-curing silicone composition according to Claim 1, wherein component (A) is an organopolysiloxane having at least two ethynyl groups in one molecule.