Thermally conductive composition, thermally conductive member, and heat dissipation structure

Abstract

[Problem] To provide: a thermally conductive composition which has extremely high thermal conductivity, and excellent extrusion workability / filling properties for small packages and the like, and in which changes in hardness and a deterioration in heat dissipation performance are suppressed even after heat aging; a thermally conductive member comprising the same; and a heat dissipation structure using the same. [Solution] Provided is a thermally conductive composition characterized by containing (A) one or more kinds of matrix polymers having a viscosity of 10-1,000,000 mPa·s at 25 °C, (B) one or more kinds of thermally conductive fillers, and (C) an organopolysiloxane represented by general formula (1) (in the formula, R1 is a monovalent hydrocarbon group that does not have a carbon-carbon double bond, R2 is a hydrogen atom or the like, a is a number from 40 to 90, and b is a number from 1 to 3). Also provided is a use of the thermally conductive composition.

Description

Thermally conductive composition, thermally conductive member, and heat dissipation structure

[0001] The present invention relates to a thermally conductive composition that has extremely high thermal conductivity, and when cured, has sufficient flexibility and stress relaxation properties for practical use. Even when heat-aged at high temperatures, the cured product changes little in hardness and maintains its flexibility, allowing it to maintain good heat dissipation properties for heat dissipation sites over a long period of time. The thermally conductive composition also has good extrudability and dischargeability from cartridges and the like, allowing it to be easily filled into small-quantity packages and providing excellent work efficiency during application. The present invention also relates to a thermally conductive member made of the composition, and a heat dissipation structure using the composition.

[0002] In recent years, with the increasing density and integration of printed circuit boards and hybrid ICs equipped with electronic components such as transistors, ICs, and memory elements, and the increasing capacity of secondary batteries (cell-type), thermally conductive silicone compositions composed of organopolysiloxanes and thermally conductive fillers such as aluminum oxide powder, aluminum hydroxide powder, and zinc oxide powder have been widely used to efficiently dissipate heat generated by electronic components, batteries, and other electronic and electrical devices. Thermally conductive silicone compositions have excellent heat resistance, and even when blended with high concentrations and high volume percentages of thermally conductive fillers, the cured product is rubbery, exhibiting a certain degree of flexibility and stress relaxation properties. This allows the composition to maintain heat-dissipating performance by maintaining the ability to follow and adhere to the heat source in a heat dissipating structure. In recent years, thermally conductive silicone compositions filled with large amounts of thermally conductive fillers have been proposed to accommodate high heat dissipation rates. In particular, the use of boron nitride powder as a thermally conductive filler with excellent thermal conductivity has been proposed (e.g., Patent Document 1, etc.).

[0003] However, in thermally conductive silicone compositions that combine these thermally conductive fillers, when a high content of a thermally conductive filler such as aluminum nitride powder is used, the rubber properties inherent in the polymeric silicone cured product generally tend to be impaired. If the content of the thermally conductive filler is too high, the resulting cured product becomes too hard, causing a gap with the heat dissipation target, impairing conformability and stress relaxation, and in fact, it may be impossible to achieve sufficient heat dissipation. In other words, in curable thermally conductive silicone compositions, controlling the hardness of the thermoelectrically conductive cured product is an extremely important issue in achieving heat dissipation. In addition, when a thermally conductive filler such as aluminum nitride powder is highly loaded, the fluidity of the composition itself tends to be impaired. When attempting to fill cartridges, dispensers, etc. with the aim of small-volume or pinpoint application, it is not possible to ensure a sufficient extrusion rate, making filling difficult, particularly for small-volume packaging, and the workability and applicability after filling may be reduced, resulting in reduced work efficiency. In addition, it becomes impossible to uniformly disperse the thermally conductive filler within the silicone composition, which can have adverse effects on the expected thermal conductivity, curing properties, workability during commercial production, etc. For this reason, high thermally conductive silicone compositions that contain a high content of thermally conductive filler such as aluminum nitride powder and that have a thermal conductivity of 9.0 W / mK or greater, in particular, have left room for improvement in terms of performance and workability for industrial widespread use.

[0004] Meanwhile, the use of a trifunctional hydrolyzable-group-containing methylpolysiloxane (sometimes referred to as a "macromonomer-type treating agent") with one end in a thermally conductive silicone rubber composition has been proposed for the purpose of adjusting the viscosity and plasticity of the thermally conductive filler (Patent Documents 2 to 9). These documents propose suppressing increases in viscosity and plasticity of thermally conductive compositions containing large amounts of thermally conductive filler by heating and mixing a mixture (sometimes referred to as a "base composition") containing a matrix polymer as the main component, a thermally conductive filler, and the macromonomer-type treating agent at a high temperature and then cooling the mixture. They disclose a siloxane degree of polymerization ranging from about 5 to 100 or from about 100 to 200. However, the examples in these documents only use siloxanes with a degree of polymerization of about 30 or greater than 100, and they do not describe or suggest the significance of limiting the degree of polymerization to a specific range, or in particular, the effects on extrusion workability, heat aging properties of the cured product, or thermal conductivity.

[0005] Additionally, these documents do not state or suggest anything about further adjusting the hardness of the cured product of hydrosilylation-curable silicone compositions by blending fatty acids or the like, or about using them in combination with heat resistance-imparting agents such as phthalocyanine compounds.

[0006] Japanese Patent Application Laid-Open No. 07-330927 Japanese Patent Application Laid-Open No. 2000-256558 (Patent Registration No. 3543663) International Publication No. 2002 / 092693 Pamphlet (US Patent No. 7329706) International Publication No. 2022 / 249754 Pamphlet Japanese Patent Application Laid-Open No. 2017-75202 (Patent Registration No. 6524879) International Publication No. 2018 / 093030 Pamphlet International Publication No. 2015 / 040777 Pamphlet Japanese Patent Application Laid-Open No. 2021-113290 (Patent Registration No. 7306278) International Publication No. 2019 / 093052 Pamphlet

[0007] Furthermore, the present inventors have discovered a new problem with hydrosilylation-curable thermally conductive silicone compositions. As described above, when a thermally conductive silicone composition containing a large amount of thermally conductive filler is cured, the cured product tends to harden, and there is often a trade-off between high thermal conductivity and flexibility of the cured product. However, even when a thermally conductive silicone composition is designed by adjusting the hardness and thermal conductivity of the cured product, in the case of a highly heat-dissipating composition containing a very high volume percentage of the thermally conductive filler (e.g., 60 volume % or more relative to the total composition (solid content)), the cured product may rapidly harden after heat aging, losing flexibility and rubber elasticity, and impairing stress relaxation properties and the ability to conform to and adhere to a heat-dissipating structure. As a result, the intended heat-dissipating properties may not be fully achieved.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a thermally conductive composition which has high thermal conductivity due to the inclusion of a thermally conductive filler such as aluminum nitride powder at a very high volume percentage, and a thermally conductive member made from the cured product which has sufficient flexibility and stress relaxation properties for practical use, and which exhibits little change in hardness and maintains flexibility even when heat-aged at high temperatures, thereby maintaining good heat dissipation properties for heat dissipation sites over a long period of time, and which is easy to extrude from a cartridge, dispenser, etc., and is particularly excellent in terms of fillability, workability, and applicability for small-quantity packages, as well as a thermally conductive member made from the same, and a heat dissipation structure using the same.

[0009] As a result of extensive investigation, the present inventors have discovered a composition comprising: (A) one or more matrix polymers having a viscosity at 25°C in the range of 10 to 1,000,000 mPa·s; (B) one or more thermally conductive fillers; and (C) a composition comprising a polymer having a general formula (1): (In the formula, R 1 are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bonds, and R ２are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, a is a number from 40 to 90, and b is a number from 1 to 3.), and the content of component (B) is in the range of 60 to 95 volume % based on the total solid content of the composition, and the inventors have found that the above-mentioned problems can be solved by a thermally conductive composition, which contains an organopolysiloxane represented by the formula (I) In other words, this composition is a thermally conductive composition that contains a large amount of a thermally conductive filler such as aluminum nitride powder (specifically, in the range of 60 to 95 volume % of the total solids content of the composition) to impart high thermal conductivity. However, by selectively using an organopolysiloxane represented by general formula (1) and having a specific siloxane polymerization degree, it is possible to achieve both extremely high thermal conductivity and coatability and workability during extrusion of the composition itself, which have traditionally been trade-offs. Furthermore, when the composition is curable and reactive, in addition to its flexibility (i.e., rubber properties), the cured product exhibits little change in hardness and maintains flexibility even after heat aging at high temperatures, making it possible to maintain good heat dissipation properties for heat dissipation sites over long periods of time. Furthermore, this composition is particularly excellent for extrusion workability from small packages.

[0010] The composition may further contain a certain amount of a surface treatment agent which is another organosilicon compound; at least one fatty acid compound selected from fatty acids, fatty acid esters, and fatty acid metal salts; and a heat resistance imparting agent (preferably a phthalocyanine compound and / or carbon black). When preparing the composition, the matrix polymer (preferably an organopolysiloxane) which is the main component of the composition, the thermally conductive filler, and a component which functions as a specific surface treatment agent (the aforementioned component (C)) may be mixed together and heated (base heat), or the matrix polymer (preferably an organopolysiloxane), the thermally conductive filler, and component (C) may be mixed and added to the mixture after base heating together with other components.

[0011] The present invention provides a thermally conductive composition or its curing reaction product, which has a very high thermal conductivity of 9.0 W / mK or more while exhibiting practically sufficient coatability, flexibility, and stress relaxation properties, and can be formed into a thermally conductive member from the composition. The composition is also extremely easy to extrude from cartridges, dispensers, etc., and can be relatively easily filled into small-volume packages such as syringes, resulting in particularly excellent workability and applicability. Furthermore, when the composition is curable, in addition to its flexibility (i.e., rubber properties), the cured product exhibits minimal change in hardness even after heat aging at high temperatures, maintaining its flexibility and stress relaxation properties, thereby enabling it to maintain excellent heat dissipation properties for heat dissipation sites over a long period of time. The present invention also provides the thermally conductive composition or a thermally conductive member obtained by curing the composition, and a heat dissipation structure using the same (particularly, a heat dissipation structure for electrical and electronic devices, including a heat dissipation structure for electrical and electronic components and a heat dissipation structure for secondary batteries).

[0012] Furthermore, the cured product of the thermally conductive composition of the present invention may further improve hardness changes and cracking during heat aging by optionally adding the aforementioned fatty acid-based compound and heat resistance imparting agent. When applied to heat dissipation targets of various shapes, even after long-term use at high temperatures, it is resistant to peeling from the heat-generating component or the formation of voids (including the formation of voids due to partial or temporary peeling from the component; the same applies hereinafter), and maintains excellent adhesion and conformability, thereby maintaining initial heat dissipation efficiency without loss. Therefore, compared to conventional products, it has superior work efficiency during extrusion, heat dissipation component durability, and heat dissipation performance, and is applicable to heat dissipation targets of various shapes. It is resistant to peeling even when used in assembly at high temperatures, and has the advantages of being usable in heat dissipation processes at high temperatures for long periods of time.

[0013] [Thermal Conductive Composition] The composition of the present invention is a thermally conductive composition comprising a matrix polymer, preferably an organopolysiloxane, a thermally conductive filler, and a macromonomer-type treating agent having a specific siloxane polymerization degree represented by the general formula (1), wherein the amount of the thermally conductive filler is specified. In particular, by selectively using a macromonomer-type treating agent having a specific siloxane polymerization degree, the cured product exhibits extremely high thermal conductivity and rubber physical properties. Even when heat-aged at high temperatures, the cured product exhibits minimal change in hardness and maintains flexibility and stress relaxation properties, thereby maintaining excellent heat dissipation properties for heat dissipation sites over a long period of time. Furthermore, the thermally conductive composition of the present invention is extremely easy to extrude from cartridges or dispensers, has excellent filling properties even in small packages, and is also excellent in workability and application efficiency (particularly extrusion workability).

[0014] The composition of the present invention may be used in an uncured state as a grease or gap filler material, or may be a composition that has a defined SiH / alkenyl group reactivity and is curable by a hydrosilylation reaction. When the composition has curing reactivity, it may contain other surface treatment agents; at least one selected from fatty acids, fatty acid esters, and fatty acid metal salts (hereinafter sometimes referred to as "fatty acid compounds"); and a heat resistance imparting agent.

[0015] The composition may be used in an uncured state or may be curable. Specifically, component (A) preferably contains (A0) one or more organopolysiloxanes having a viscosity at 25°C in the range of 10 to 1,000,000 mPa·s. The organopolysiloxane may be one or more organopolysiloxanes selected from (A1) organopolysiloxanes having no curable groups with carbon-carbon double bonds in the molecule and (A2) organopolysiloxanes having curable groups with carbon-carbon double bonds in the molecule. A curable composition using component (A2) may further contain (D) an organohydrogenpolysiloxane and (E) a catalytic amount of a hydrosilylation catalyst, and may optionally contain (F) a heat resistance imparting agent and (G) a fatty acid-based compound. The composition may also contain a hydrosilylation reaction inhibitor, an adhesion promoter, an organic solvent, and other additives. The composition of the present invention may be a one-component composition or a multi-component composition such as a two-component composition. Each component and its amount to be added will be described below.

[0016] Hereinafter, the average particle diameter of each component (including spherical and irregular shapes) of the thermally conductive filler, which is component (B), is the cumulative average particle diameter D ５０ This is the median diameter, and can be measured using a laser diffraction particle size distribution analyzer commonly used in the field. Based on the same principle, the content (volume %) of coarse particles having a certain particle size or less can be determined using a laser diffraction particle size distribution analyzer. Furthermore, component (C), which will be described later, does not overlap with the organopolysiloxane, which is component (A), and is therefore excluded from its scope.

[0017] [(A) Matrix Polymer] Component (A) is a matrix polymer for supporting the thermally conductive filler. It can be any curable or non-curable liquid or flowable polymeric material with a viscosity at 25° C. ranging from 10 to 1,000,000 mPa·s, preferably from 10 to 10,000 mPa·s, without any particular limitation. For example, organopolysiloxane, liquid polyurethane resin, liquid polyester resin, liquid acrylic resin, liquid polyol resin, liquid butadiene rubber, liquid isoprene rubber, liquid styrene-butadiene rubber, etc. can be used without any limitation. However, since the thermally conductive composition according to the present invention is used in semiconductor devices that generate high temperatures, it is particularly preferable that it contains one or more organopolysiloxanes (A0) with excellent heat resistance and cold resistance and a viscosity at 25° C. ranging from 10 to 1,000,000 mPa·s.

[0018] The organopolysiloxane of component (A0) is the main component of the composition and is one or more organopolysiloxanes having a viscosity at 25°C ranging from 10 to 1,000,000 mPa·s. The viscosity of component (A) at 25°C is preferably in the range of 10 to 100,000 mPa·s, and more preferably in the range of 10 to 10,000 mPa·s. If the viscosity of component (A) is less than 10 mPa·s, the mechanical strength of the resulting organopolysiloxane composition or its cured product tends to decrease. On the other hand, if the viscosity exceeds 100,000 mPa·s, the resulting composition tends to be too viscous, resulting in poor handling and poor application to fine details. From the standpoint of preventing contact failure, it is preferable that component (A) contain reduced or eliminated low-molecular-weight siloxane oligomers (octamethyltetrasiloxane (D4), decamethylpentasiloxane (D5)).

[0019] Component (A) may be composed of one or more organopolysiloxanes. The molecular structure of such organopolysiloxanes is not particularly limited, and examples include linear, branched, cyclic, and three-dimensional network structures (including so-called resin-like three-dimensional structures), as well as combinations thereof.

[0020] Depending on the presence or absence of a curing reactive group in component (A), the composition can be designed as a curable or non-curable composition. The curing reactive group is a functional group that can cure the entire composition through a crosslinking reaction (including gelation, the same applies hereinafter). The type of curing reactive group is not particularly limited, but is preferably hydrosilylation reactive or radical polymerization reactive, and is particularly preferably a curing reactive group having a carbon-carbon double bond in the molecule. Furthermore, the curing reactive group having a carbon-carbon double bond in the molecule is preferably at least one organic group selected from an alkenyl group, a methacryloxy group-containing organic group, and an acryloxy group-containing organic group, and is particularly preferably an alkenyl group having 2 to 20 carbon atoms.

[0021] Preferably, component (A) is one or more organopolysiloxanes selected from (A1) organopolysiloxanes that do not have a curing reactive group that has a carbon-carbon double bond in the molecule and (A2) organopolysiloxanes that have a curing reactive group that has a carbon-carbon double bond in the molecule, and component (A1) alone, component (A2) alone, or both may be used in combination. Note that when component (A2) is used as at least a portion of component (A), the composition can be designed to be curable.

[0022] Component (A1) is an organopolysiloxane that does not contain a curing reactive group having a carbon-carbon double bond in the molecule, and does not contain a curing reactive group such as the alkenyl group, methacryloxy group-containing organic group, or acryloxy group-containing organic group in the molecule, making it suitable as a base agent for non-curing thermally conductive organopolysiloxane compositions, such as thermally conductive greases and non-curing thermally conductive gap filler materials. The functional group in component (A1) is a group other than the curing reactive functional group, and examples of such functional groups include alkyl groups such as methyl groups; aryl groups such as phenyl groups; and monovalent hydrocarbon groups other than alkenyl groups, such as halogenated alkyl groups such as 3,3,3-trifluoropropyl groups, with methyl or phenyl groups being industrially preferred.

[0023] Particularly preferred is a linear, non-curable organopolysiloxane as component (A1), such as a dimethylpolysiloxane terminally capped with trimethylsiloxy groups, a dimethylsiloxane-methylphenylsiloxane copolymer terminally capped with trimethylsiloxy groups, a dimethylsiloxane copolymer terminally capped with silanol groups, a polymer in which some of the methyl groups have been substituted with alkyl groups other than methyl, such as ethyl or propyl, or with halogenated alkyl groups such as 3,3,3-trifluoropropyl, or a mixture of two or more of these polymers. As mentioned above, the organopolysiloxane of component (C), described below, is excluded from the scope of component (A), and these components do not overlap.

[0024] Component (A2) is an organopolysiloxane having a curable reactive group having a carbon-carbon double bond in the molecule, and the curable reactive group having a carbon-carbon double bond in the molecule has at least one organic group selected from an alkenyl group, a methacryloxy group-containing organic group, and an acryloxy group-containing organic group in the molecule. Therefore, the component (A2) is suitable as a base agent for curable thermally conductive organopolysiloxane compositions, such as curable thermally conductive elastomers, thermally conductive gels, and curable thermally conductive gap filler materials.

[0025] Examples of alkenyl groups in the molecule of component (A2) include vinyl, allyl, butenyl, and hexenyl groups. Examples of organic groups other than alkenyl groups in component (A2) include monovalent hydrocarbon groups other than alkenyl groups, such as alkyl groups such as methyl, aryl groups such as phenyl, and halogenated alkyl groups such as 3,3,3-trifluoropropyl, with methyl and phenyl being industrially preferred.

[0026] Particularly preferred examples of component (A2) are linear alkenyl-containing organopolysiloxanes, such as dimethylpolysiloxanes terminally blocked with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminally blocked with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers terminally blocked with silanol groups, polymers in which some of the methyl groups in these polymers have been substituted with alkyl groups other than methyl, such as ethyl or propyl, or halogenated alkyl groups such as 3,3,3-trifluoropropyl, polymers in which the vinyl groups in these polymers have been substituted with alkenyl groups other than vinyl, such as allyl, butenyl, or hexenyl, and mixtures of two or more of these polymers.

[0027] When component (A) contains component (A2), the composition may and preferably contains, as a curing agent, (D) an organohydrogenpolysiloxane, and (E) a catalytic amount of a hydrosilylation reaction catalyst.

[0028] [(D) Organohydrogenpolysiloxane] Component (D) is the primary crosslinking agent of the composition of the present invention, and any organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms in the molecule can be used without particular limitation, but from the standpoint of flexibility of the resulting cured product and adhesion retention to substrates, it is preferable that the number (average) of silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane molecule does not exceed 8. In particular, it is preferable to include at least (D1) a linear organohydrogenpolysiloxane having a viscosity at 25°C of 1 to 1,000 mPa s and containing an average of 2 to 4 silicon-bonded hydrogen atoms in the molecule, with at least one of these, on average, located in a side chain on the molecular chain.

[0029] Examples of such component (D1) include a methylhydrogensiloxane-dimethylsiloxane copolymer terminated at both molecular chain terminals with trimethylsiloxy groups, and a methylhydrogensiloxane-dimethylsiloxane copolymer terminated at both molecular chain terminals with dimethylhydrogensiloxy groups. Note that these examples are not limiting, and some of the methyl groups may be substituted with phenyl groups, hydroxyl groups, alkoxy groups, etc.

[0030] The viscosity of component (D1) at 25°C is not particularly limited, but is preferably in the range of 1 to 500 mPa s, and particularly preferably in the range of 1 to 100 mPa s. Furthermore, from the standpoint of preventing contact failure, it is preferable that the content of low-molecular-weight siloxane oligomers (octamethyltetrasiloxane (D4), decamethylpentasiloxane (D5)) be reduced or eliminated.

[0031] [Amount of Organohydrogenpolysiloxane (Crosslinking Agent) in Composition] From the viewpoint of the rubber properties, mechanical strength, and adhesive properties of the resulting organopolysiloxane cured product, the composition of the present invention contains component (D) in an amount such that the number of silicon-bonded hydrogen atoms in component (A) is 0.2 to 5.0 moles, particularly preferably 0.3 to 3.0 moles, or 0.4 to 2.0 moles per mole of alkenyl groups in component (A).

[0032] [(E) Hydrosilylation Catalyst] The hydrosilylation catalyst is a component used to cure the present composition. Examples include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Platinum-based catalysts are preferred because they significantly accelerate the curing of the present composition. Examples of platinum-based catalysts include platinum fine powder, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-alkenylsiloxane complexes, platinum-olefin complexes, platinum-carbonyl complexes, and catalysts in which these platinum-based catalysts are dispersed or encapsulated in thermoplastic resins such as silicone resins, polycarbonate resins, and acrylic resins. Platinum-alkenylsiloxane complexes are particularly preferred. Platinum 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes are particularly preferred, and the complex is preferably added in the form of an alkenylsiloxane solution. In addition, from the viewpoint of improving handling and workability and the pot life of the composition, a platinum-containing hydrosilylation catalyst in the form of fine particles dispersed or encapsulated in a thermoplastic resin may be used. Note that non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt may also be used as catalysts for promoting the hydrosilylation reaction.

[0033] On the other hand, the hydrosilylation reaction catalyst may be a so-called high-energy ray-activated catalyst or photoactivated catalyst, such as a (methylcyclopentadienyl)trimethylplatinum(IV) complex or a bis(2,4-pentanedionato)platinum(II) complex. By using such a hydrosilylation reaction catalyst, the composition as a whole can be cured even at low temperatures using high-energy ray irradiation as a trigger, and the composition may have excellent storage stability and easy reaction control, resulting in excellent handling and workability. In this case, ultraviolet light is preferred as the high-energy ray from the viewpoint of catalyst activation efficiency, and ultraviolet light with a wavelength in the range of 280 to 380 nm is preferred from the viewpoint of industrial use. The irradiation dose varies depending on the type of high-energy ray-activated catalyst, but in the case of ultraviolet light, the cumulative irradiation dose at a wavelength of 365 nm is 100 mJ / cm. ２ ~100 J / cm ２ It is preferable that the range is within the range of

[0034] The amount of the hydrosilylation catalyst added may be any catalytic amount, and more specifically, it is an amount that results in a metal atom concentration in the range of 0.01 to 500 ppm by mass, 0.01 to 100 ppm by mass, or 0.01 to 50 ppm by mass, relative to the total composition.

[0035] [(B) Thermally Conductive Filler] Component (B) is one or more thermally conductive fillers that impart thermal conductivity to the composition and the thermally conductive member obtained by curing the composition. Component (B) is preferably at least one powder and / or fiber selected from the group consisting of pure metals, alloys, metal oxides, metal hydroxides, metal nitrides, metal carbides, metal silicides, carbon, soft magnetic alloys, and ferrites, and is preferably a metal-based powder, metal oxide-based powder, metal nitride-based powder, or carbon powder. The shape of component (B) is not particularly limited, but examples include spherical, acicular, discoid, rod-like, and irregular shapes. Preferably, it is spherical or irregular. The average particle size of component (B) is also not particularly limited, but is preferably in the range of 0.01 to 500 μm, more preferably 0.01 to 300 μm.

[0036] Suitable examples of component (B) include silver powder, aluminum powder, aluminum oxide powder, zinc oxide powder, aluminum nitride powder, boron nitride powder, and graphite. When electrical insulation is required for the composition, metal oxide powders or metal nitride powders are preferred, and aluminum oxide powder, zinc oxide powder, boron nitride powder, and aluminum nitride powder are particularly preferred.

[0037] The combination of component (B) is not particularly limited, but examples include (b1-1) plate-shaped boron nitride powder having an average particle size of 0.1 to 150 μm, (b1-2) granular or spherically molded boron nitride powder having an average particle size of 0.1 to 500 μm, (b1-3) spherical fused and / or crushed aluminum oxide powder having an average particle size of 0.01 to 150 μm, (b1-4) amorphous or spherical aluminum nitride powder having an average particle size of 0.1 to 150 μm, or (b1-5) spherical and / or crushed graphite having an average particle size of 0.01 to 50 μm, or a mixture of two or more of these. One example of a suitable component (B) is a mixture of two or more spherical and crushed aluminum oxide powders having an average particle size of 0.01 to 50 μm. In particular, as exemplified by the examples of the present application, by combining aluminum oxide powder with large particle size and aluminum oxide powder with small particle size in a ratio that follows the closest packing theoretical distribution curve, the packing efficiency is improved, and low viscosity and high thermal conductivity are possible.

[0038] Furthermore, from the viewpoint of improving the thermal conductivity of the cured product without impairing the rubber properties and workability during extrusion of the thermally conductive composition of the present invention, it is preferable that component (B) is substantially free of thermally conductive fillers having an average particle size of less than 2.0 μm, particularly aluminum nitride powder (hereinafter sometimes referred to as "coarse particles"). Here, "substantially free" means that the content of thermally conductive fillers having an average particle size of less than 2.0 μm, particularly aluminum nitride powder, in the entire thermally conductive filler is less than 0.5 vol%, more preferably less than 0.1 vol%, and particularly preferably below the detection limit (= 0.0 vol%). On the other hand, if the thermally conductive filler contains 0.5 mass% or more of aluminum nitride powder having an average particle size of less than 2.0 μm, the technical effects of the present invention may not be fully achieved.

[0039] Furthermore, from the viewpoint of the rubber properties and good workability during extrusion of the thermally conductive composition of the present invention, the following may and preferably be used in combination: (b2-1) at least one thermally conductive filler selected from zinc oxide powder and aluminum oxide powder, each having an average particle size in the range of 0.1 to 1.0 μm; (b2-2) at least one thermally conductive filler selected from aluminum nitride powder and aluminum oxide powder, each having an average particle size in the range of 2.0 to 29 μm, each having an irregular, rounded, and polyhedral shape; (b2-3) aluminum nitride powder, each having an average particle size of 30 μm or more, each having an irregular, rounded, and polyhedral shape; and (b2-4) aluminum nitride powder, each having an average particle size of more than 50 μm, each having a spherical shape. These suitable thermally conductive fillers in the present invention are described below. Selecting these thermally conductive fillers as component (B) and using them in combination with component (C) may particularly effectively solve the technical problems of the present invention.

[0040] Component (b2-1) is at least one thermally conductive filler selected from zinc oxide powder and aluminum oxide powder, having an average particle size in the range of 0.1 to 1.0 μm. Its shape is not particularly limited, but examples include spherical, acicular, discoid, rod, and irregular shapes, with spherical and irregular shapes being preferred. Incidentally, spherical shapes include polyhedral spherical shapes. The average particle size of component (A) is preferably in the range of 0.10 to 0.75 μm, and may be in the range of 0.10 to 0.60 μm.

[0041] Component (b2-1) has the smallest average particle size among the thermally conductive fillers of the present invention and is added for the purpose of dense packing. By using this component in combination with aluminum nitride powder, etc., described below, in a certain quantitative range, the thermal conductivity of the cured product can be improved without impairing the rubber properties or workability during extrusion.

[0042] Component (b2-2) is an aluminum nitride powder or aluminum oxide powder having an average particle diameter in the range of 2.0 to 29 μm and selected from amorphous, rounded, and polyhedral shapes. The shape of component (b2-2) is preferably amorphous, excluding spherical and polyhedral spherical shapes. In other words, spherical and polyhedral spherical components are explicitly excluded from the scope of component (b2-2). Furthermore, in the present invention, amorphous refers to particles that do not have a fixed shape but have multiple corners and protrusions, and are clearly distinguishable from symmetrical spherical and polyhedral spherical shapes. Furthermore, rounded refers to smooth particles with few corners and a rounded shape, but still have corners and protrusions, and are therefore clearly distinguishable from the symmetrical spherical and polyhedral spherical shapes. Furthermore, polyhedral refers to particles that do not have rounded spherical surfaces, and are therefore clearly distinguishable from symmetrical spherical and polyhedral spherical shapes. Spherical particles are not preferred because they have no corners, making contact difficult and resulting in poor thermal conductivity. In the present invention, the most suitable component (b2-2) is aluminum nitride powder or aluminum oxide powder that is irregular and has an average particle size in the range of 2.0 to 29 μm. The average particle size of component (b2-2) is preferably in the range of 2.1 to 25 μm, and may be in the range of 2.4 to 15.0 μm. If the type of component (b2-2) is different or the particle size is below the lower limit, workability may be impaired, particularly during extrusion, or a paste-like composition may not be obtained in the first place, making extrusion from a cartridge or dispenser difficult.

[0043] Component (b2-3) is an aluminum nitride powder having an average particle size of 30 μm or more and selected from amorphous, rounded, and polyhedral shapes, and is a component that, when used in combination with components (b2-1) and (b2-2) in a certain quantitative range, achieves the technical effects of the present invention and achieves extremely high thermal conductivity without causing any problems with anisotropy. Note that component (b2-2) is defined by the upper limit of its average particle size.

[0044] The shape of component (b2-3) is preferably irregular, and does not include spherical or polyhedral spherical shapes. The terms "irregular," "rounded," and "polyhedral" are the same as those described for component (B), and components (b2-3) having these shapes are clearly distinguishable in shape from symmetrical spherical or polyhedral spherical particles. In the present invention, the most suitable component (b2-3) is an aluminum nitride powder that is irregular and has an average particle size in the range of 30 μm or more. Furthermore, in the present invention, the component (b2-3) described below can be used in combination as a large-particle-size, spherical aluminum nitride powder, and this is preferred.

[0045] The average particle size of component (b2-3) is 30 μm or more, and may be 30 to 300 μm, or may be in the range of 30 to 180 μm. Furthermore, as described above, component (b2-3) preferably does not contain aluminum nitride powder with an average particle size of less than 2.0 μm, and component (b2-3) containing such particles at a concentration of 1 vol% or less, preferably 0 vol% or less to one significant digit, is most preferred. This is because if the content of low-particle-size aluminum nitride powder is high, even if a specific amount of component (b2-3) is used, the influence of the low-particle-size aluminum nitride powder may impair workability during extrusion, or a paste-like composition may not be obtained, making the extrusion itself difficult.

[0046] Component (b2-4) is a spherical aluminum nitride powder with an average particle size exceeding 50 μm, and although it is an optional component in the present invention, it is a component that further improves the technical effects of the present invention and achieves extremely high thermal conductivity without causing problems with anisotropy, particularly when used in combination with components (b2-1), (b2-2), and (b2-3) in a certain quantitative range. Note that it is distinguished from component (b2-2) by the upper limit of its average particle size, and from component (b2-3) by its shape.

[0047] The average particle size of component (b2-4) exceeds 50 μm, and may be in the range of 51 to 300 μm, or may be in the range of 51 to 180 μm. Furthermore, component (b2-4) preferably does not contain aluminum nitride powder with an average particle size of less than 2.0 μm, and component (b2-4) in which the amount of such particles mixed in is 1% by volume or less, preferably 0% by volume or less to one significant digit, is most preferred. The reasons for this are the same as those stated for component (b2-3).

[0048] [Amount of (B) Thermally Conductive Filler] The composition of the present invention has an extremely high thermal conductivity of 9.0 W / mK or more, and can form a cured product having sufficient flexibility and stress relaxation properties for practical use, as well as a thermally conductive component made from the cured product. Furthermore, when filled into a cartridge or the like, the composition is in a paste form, which allows for excellent work efficiency during extrusion. To achieve this, it is necessary to set the amount of the above-mentioned components within a specific range.

[0049] Specifically, in the present invention, to achieve high thermal conductivity, the content of the thermally conductive filler (component (B)) is in the range of 60 to 95% by volume, preferably 65 to 95% by volume, 70 to 93% by volume, or 75 to 92% by volume, based on the total solids content of the composition. If the content of the thermally conductive filler is below the lower limit, the thermal conductivity of the resulting composition is likely to decrease, and the high thermal conductivity desired in the present invention, particularly a high thermal conductivity of 9.0 W / mK or higher, may not be achieved. On the other hand, if the content exceeds the upper limit of the above range, even when component (C), described below, is blended or used for surface treatment of the filler, the viscosity of the resulting composition may be significantly increased, or the initial cured product may become significantly hard, resulting in reduced handling, stress relaxation properties, and adhesion to substrates.

[0050] The total amount of the thermally conductive filler used as component (B) is more preferably in the range of 600 to 6,000 parts by mass, and particularly preferably in the range of 800 to 4,000 parts by mass, per 100 parts by mass of component (A). When the amount of the thermally conductive filler used is in the above-mentioned volume percent range and the amount used relative to component (A) satisfies the above-mentioned range, the problem of the present invention can be particularly suitably solved.

[0051] Preferably, the content of the component (b2-3) is in the range of 1.0 to 20.0% by volume, more preferably 2.0 to 20.0% by volume, and even more preferably 3.0 to 19.0% by volume, based on the total solid content of the composition.

[0052] Since component (D) is an optional component of the present invention, its content is in the range of 0.0 to 30.0 vol%, preferably 3.0 to 30.0 vol%, or 5.0 to 30.0 vol%, based on the total solid content of the composition.

[0053] Furthermore, the content of the amorphous aluminum nitride powder selected from component (b2-2) and component (b2-3) is preferably 50 mass % or less relative to the total solid content in the composition.

[0054] Furthermore, it is particularly preferable that the total content of the thermally conductive filler, which is aluminum nitride powder, is 60 mass % or less relative to the total solid content in the composition. Aluminum nitride powder is prone to internal cracking due to ammonia gas generated by hydrolysis, and this tendency becomes more pronounced as the filling amount increases. Therefore, minimizing the amount used is effective in solving this problem.

[0055] In addition, in order to improve the filling efficiency of other thermally conductive fillers, for example, by combining powders with large particle sizes and powders with small particle sizes in a ratio that follows the closest packing theoretical distribution curve, the filling efficiency can be improved, and lower viscosity and higher thermal conductivity can be achieved.

[0056] [Other Inorganic Fillers] The composition of the present invention may optionally contain inorganic fillers (also referred to as "inorganic fillers") such as fumed silica, wet silica, crushed quartz, titanium oxide, magnesium carbonate, zinc oxide, iron oxide, diatomaceous earth, and carbon black, as well as inorganic fillers obtained by hydrophobizing the surface of such inorganic fillers with component (E) described below and / or other organosilicon compounds (silazanes, etc.). However, from the standpoint of achieving the technical effects of the present invention, particularly high thermal conductivity, flexibility and stress relaxation properties of the cured product, ease of extrusion from cartridges, and adhesion to substrates, the composition may be substantially free of fillers other than the thermally conductive filler (component (B)). On the other hand, for the purpose of achieving other functions such as improving (reinforcing) mechanical strength and adjusting viscosity, the above fillers may be used in combination to the extent that the technical effects of the present invention are not impaired, and this is included in one of the preferred embodiments of the present invention.

[0057] [(C) Macromonomer-type Treatment Agent with a Specific Degree of Polymerization] Component (C) is one of the components that characterize the composition of the present invention. The use of this component improves the extrusion and discharge properties of the thermally conductive composition from cartridges, etc., resulting in a composition that is easy to fill into small-volume packages and has excellent workability during application. Furthermore, even when the cured product is heat-aged at high temperatures, the hardness of the cured product changes little, and flexibility and stress relaxation properties are maintained, making it possible to maintain good heat dissipation properties for heat dissipation sites for a long period of time. In particular, component (C) is a component that is critical in terms of its siloxane polymerization degree a.

[0058] Specifically, component (C) is a compound represented by general formula (1): (In the formula, R 1 are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bonds, and R ２ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, a is a number from 40 to 90, and b is an integer from 1 to 3, and has a viscosity at 25°C of 10 to less than 10,000 mPa·s.

[0059] In general formula (1), R 1are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bond, examples of which include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups. 1 is preferably a methyl group or a phenyl group, and from the viewpoint of heat resistance, a methyl group is preferred.

[0060] R ２ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. ２ is preferably an alkyl group, and particularly preferably a methyl group or an ethyl group.

[0061] In general formula (1), when the degree of polymerization of siloxane, a, is within a specific range, the extrusion workability of the composition and the heat aging properties and thermal conductivity of the cured product can be further improved. However, when the value of a is not within the specific range (for example, when a is 30 or 100), even if an organopolysiloxane represented by general formula (1) is used, the extrusion workability of the composition according to the present invention and the heat aging properties of the cured product may not be sufficiently improved. Specifically, a in general formula (1) must be a number in the range of 40 to 90, and particularly preferably a number in the range of 40 to 90, 45 to 90, 50 to 90, or 50 to 80. Furthermore, OR ２ The number b of terminal hydrolyzable groups represented by the formula (I) is an integer of 1 to 3, preferably 2 or 3. Component (C) according to the present invention is preferably a copolymer in which b is 3, one molecular chain terminal has a trialkoxysiloxy group, and R 1 A suitable example is polydimethylsiloxane in which is a methyl group.

[0062] Component (C) is a component that functions as a surface treatment agent for thermally conductive fillers and other inorganic fillers, and may coexist with these components in the composition. Preferably, the inorganic filler, component (B), is surface-treated with component (C), which is particularly preferred for the purpose of further improving the uniform dispersion of these components and the handling and workability of the resulting composition, particularly the extrusion workability of the composition, and the heat aging properties and thermal conductivity of the cured product.

[0063] [(C'), (C'') Other Surface Treatment Agents] In the present invention, in addition to the component (C), (C') a surface treatment agent represented by the general formula (2): R alk R ３ ２ SiO(R ３ ２ SiO) ｃ R ３ ２ Si-R ４ -SiR ３ (3-ｄ) (OR ５ ) ｄ (In the formula, R alk is an alkenyl group, and R ３ are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bonds, and R ４ is an oxygen atom or a divalent hydrocarbon group, and R ５ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, c is an integer of 1 to 250, and d is an integer of 1 to 3.) and have a viscosity at 25°C in the range of 10 to 10,000 mPa·s and have an alkenyl group and a hydrolyzable silyl group at the molecular chain terminal; and (C") an alkoxysilane having an alkyl group having 6 or more carbon atoms in the molecule, or a hydrolyzed condensate thereof.

[0064] Regarding component (C'), R in general formula (2) alk is an alkenyl group, examples of which include alkenyl groups having 2 to 10 carbon atoms, such as vinyl, allyl, and hexenyl. Because component (C') has an alkenyl group at one end of the molecular chain, it is effective as a surface treatment agent for component (B), the thermally conductive filler, and may also improve the curing properties and adhesive properties when used in combination with other crosslinking agents.

[0065] In the formula, R ３R are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bond, and examples thereof include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups. From an industrial viewpoint, R is preferably a methyl group or a phenyl group, and from the viewpoint of heat resistance, R is preferably a methyl group. ４ is an oxygen atom or a divalent hydrocarbon group. ４ Examples of the divalent hydrocarbon group include alkylene groups such as a methylene group; and alkyleneoxyalkylene groups such as an ethyleneoxyethylene group and an ethyleneoxypropylene group. ４ may be, and preferably is, an oxygen atom.

[0066] In the formula, R ５ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, and are preferably alkyl groups. From the viewpoint of surface treatment, methyl groups and ethyl groups are particularly preferred. Component (C') is Si(OR ５ ) has a hydrolyzable silyl group in the molecule, and therefore has an excellent surface treatment effect when used in combination with component (C).

[0067] In the formula, c is the degree of polymerization of the diorganosiloxane unit in component (C') (excluding the terminals) and is an integer of 1 to 250, preferably an integer of 1 to 100, and particularly preferably an integer of 1 to 50. In the formula, d is an integer of 1 to 3, preferably 3. When d is 3, one terminal of component (C') is particularly preferably a trimethoxysilyl group (-Si(OMe) ３ )

[0068] The blending amounts of component (C) and component (C') (the total amount when both are used) are not particularly limited as long as they are an amount sufficient for surface treatment of the filler, but as an example, they are in the range of 0.005 to 100 parts by mass, preferably 0.05 to 100 parts by mass, and more preferably 0.5 to 50 parts by mass per 100 parts by mass of component (B) in the entire composition.

[0069] Component (C") is an alkoxysilane or a hydrolysis condensate thereof having an alkyl group having 6 or more carbon atoms in the molecule, and is particularly preferably used in combination with component (C) as a surface treatment agent for component (B).

[0070] Like component (C) or (C'), component (C") functions as a surface treatment agent for component (B), the thermally conductive filler, in the composition, improving the amount of component (B) incorporated, improving the viscosity and flowability of the entire composition, and improving the adhesive properties. Such alkoxysilanes preferably have an alkyl group of C6 or more.

[0071] Specific examples of alkyl groups having 6 or more carbon atoms include alkyl groups such as hexyl, octyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups, and aralkyl groups such as benzyl and phenylethyl groups, with alkyl groups having 6 to 20 carbon atoms being particularly preferred.

[0072] Preferably, component (C") has the following structural formula: ｎ Si(OR) ４－ｎ (wherein Y is an alkyl group having 6 to 18 carbon atoms, R is an alkyl group having 1 to 5 carbon atoms, and n is a number from 1 to 3), and examples of the OR group include methoxy, ethoxy, propoxy, and butoxy groups, with methoxy and ethoxy groups being particularly preferred. Note that n is 1, 2, or 3, with 1 being particularly preferred.

[0073] Such a component (C") is specifically CH 13 Si(OCH3)3, C8H 17 Si(OC2H5)3,C 10 H 21 Si(OCH3)3, C 11 H 23 Si(OCH3)3, C 12 H 25 Si(OCH3)3, C 14 H 29 Examples include Si(OC2H5)3, and the most preferred is decyltrimethoxysilane.

[0074] The amount of component (C") to be blended is not particularly limited as long as it is an amount sufficient for surface treatment of the filler, but as an example, it is in the range of 0.005 to 20 parts by mass, preferably 0.05 to 10 parts by mass, and more preferably 0.5 to 7.5 parts by mass, per 100 parts by mass of component (A) in the entire composition.

[0075] [Surface Treatment of (B) Thermally Conductive Filler and Other Inorganic Fillers] In the present invention, the thermally conductive filler (B) and any inorganic fillers used as needed (hereinafter, these components are collectively referred to as "fillers") are preferably surface-treated with at least a portion of the above-mentioned component (C), and it is particularly preferable to perform the surface treatment using one or more components selected from component (C') and component (C") in combination. Furthermore, these fillers may be treated with various surface treatment agents known as coupling agents in addition to these components. Surface treatment agents for treating the fillers of the present invention include, in addition to components (C), (C'), and (C"), surfactants, other silane coupling agents, aluminum-based coupling agents, and silicone-based surface treatment agents.

[0076] The method for surface treating the filler with these components is not particularly limited, but examples include direct treatment of the filler, integral blending, and dry concentrate. In the present invention, from the standpoint of improving the fillability of the composition as a whole and the thermal conductivity, rubber physical properties, and adhesive strength of the cured product, a thermal surface treatment method is most suitable, in which a surface treatment agent such as component (C) described below is premixed with part or all of component (A), and the filler is sequentially mixed into the mixture, homogenized, and then heated (base heat). In this surface treatment method, the mixture can be heated and stirred at 100 to 200°C under reduced pressure. The temperature conditions and stirring time can be designed depending on the amount of sample, but are preferably in the range of 120 to 180°C and 0.25 to 10 hours. The surface treatment step of the filler is optional, but from the viewpoint of improving the extrusion workability and thermal conductivity of the present composition, it may be a stepwise treatment step including a step in which at least a portion of the filler is surface treated with component (C) and optionally further with component (C'), and then the filler is surface treated with component (C"). The use of a surface treatment agent containing component (C) of the present invention can particularly improve the extrusion workability of the composition.

[0077] The apparatus used for the above mixing is not particularly limited, and examples thereof include a single-screw or twin-screw continuous mixer, a two-roll mill, a Ross mixer, a Hobart mixer, a dental mixer, a planetary mixer, a kneader mixer, and a Henschel mixer.

[0078] [(F) Heat Resistance Imparting Agent] In addition to the above-mentioned components, the composition of the present invention may optionally contain a heat resistance imparting agent. While the heat resistance imparting agent may be used alone, the technical effects of the composition of the present invention and its cured product may be further improved by using it in combination with a (G) fatty acid compound, as described below. The amount of the heat resistance imparting agent may be in the range of 0.01 to 5.0 mass %, 0.05 to 2.0 mass %, or 0.07 to 0.5 mass %, of the total composition (solid content).

[0079] Examples of heat resistance-imparting agents include metal oxides such as iron oxide, titanium oxide, cerium oxide, magnesium oxide, and zinc oxide; metal hydroxides such as cerium hydroxide; phthalocyanine compounds; cerium silanolates; cerium fatty acid salts; reaction products of organopolysiloxanes and cerium carboxylates; and carbon black. Particularly preferred are (F1) phthalocyanine compounds, such as those disclosed in JP-A-2014-503680. Additives selected from the group consisting of metal-free phthalocyanine compounds and metal-containing phthalocyanine compounds are preferably used. Of the metal-containing phthalocyanine compounds, copper phthalocyanine compounds are particularly preferred. One of the most preferred, non-limiting examples of the heat resistance-imparting agent is 29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32 copper. Such phthalocyanine compounds are commercially available, for example, Stan-tone™ 40SP03 from PolyOne Corporation (Avon Lake, Ohio, USA). Similarly, by blending (F2) carbon black as a heat resistance imparting agent in an amount of 0.1 to 5 mass %, preferably 0.2 to 2 mass %, based on the total mass of the composition, it is possible to satisfactorily improve the heat aging properties at 180°C or higher and the high-temperature heat resistance.

[0080] [(G) Fatty Acid Compound] When the composition of the present invention is curable, in addition to the above-mentioned components, it may optionally contain at least one fatty acid compound selected from fatty acid esters and fatty acid metal salts. This component suppresses the hardness change during heat aging of the composition and the cured product obtained by curing the composition, which is a silicone-based thermally conductive member. In particular, when the amount of the thermally conductive filler is within the above-mentioned range, the use of component (G) in addition to component (C) can further suppress the hardness change during heat aging of the cured product. This prevents the cured product from rapidly hardening during heat aging, thereby preventing its stress relaxation properties, flexibility, and substrate adhesion from being impaired. By using component (G) in combination with, preferably, the heat resistance imparting agent (component (F)) in the hydrosilylation curing reactive composition, the resulting cured product has high thermal conductivity, maintains its initial hardness and rubber physical properties, and achieves good stress relaxation properties, flexibility, and substrate adhesion.

[0081] Specifically, component (G) is at least one selected from fatty acids, fatty acid esters, and fatty acid metal salts, and examples thereof include fatty acids such as caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and oleic acid; fatty acid esters that are alkyl esters thereof; alkali metal salts of fatty acids such as sodium, lithium, and potassium; and alkaline earth metal salts of fatty acids such as calcium. Preferably, component (G) is at least one selected from saturated fatty acids and saturated fatty acid metal salts, and particularly preferably (G1) stearic acid, alkali metal salts of stearic acid, and alkaline earth metal salts of stearic acid.

[0082] The mechanism by which component (G), when used in combination with component (C), and optionally with component (F), inhibits changes in hardness of the cured product has not been clearly identified, but it is speculated that the presence of limited amounts of fatty acid-based compounds such as fatty acids, fatty acid salts (soaps), and fatty acid esters in the silicone cured product matrix, whose heat resistance has been improved in the presence of component (C) and optionally component (F), causes the formation of a water-resistant and lubricating thin film or local structure composed of these fatty acid-based compounds on or near the particle surfaces of the thermally conductive filler, chemically reducing or inactivating the particle surfaces at high temperatures and effectively preventing aggregation of the surfaces of the thermally conductive filler and the formation of coarse particles. However, since component (G) exerts its technical effect simply by being uniformly mixed with other components without being used as a surface treatment agent for the thermally conductive filler, the timing of adding component (G) to the composition in the present invention is not limited.

[0083] The amount of component (G) is preferably in the range of 0.05 to 2.0 parts by mass per 100 parts by mass of the thermally conductive filler (B) (total amount if multiple components are present). If the amount of component (G) is less than the lower limit, it may be insufficient to further improve the hardness change of the cured product when used in combination with component (C). On the other hand, if the amount of component (G) is more than the upper limit, it may similarly be insufficient to improve the effect of suppressing hardness change of the cured product.

[0084] [(H) Hydrosilylation Reaction Inhibitor, Adhesion Promoter, Organic Solvent, and Other Additives] The composition of the present invention essentially comprises components (A) to (C). When component (A) contains curable component (A2), it preferably further contains components (D) and (E). It is more preferable to optionally contain one or more components selected from components (C'), (C"), (F), and (G). It is particularly preferable to use components (C"), (F), and (G) in combination. However, the composition may further contain the following other components. In particular, when the composition is curable, it is particularly preferable to use a hydrosilylation reaction inhibitor.

[0085] [Hydrosilylation Reaction Inhibitor] When the composition of the present invention is curable, it is preferable from the viewpoint of handling and workability that it further contain a hydrosilylation reaction inhibitor. The hydrosilylation reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the thermally conductive organopolysiloxane composition of the present invention, and specific examples include acetylene-based inhibitors such as ethynylcyclohexanol, amine-based inhibitors, carboxylic acid ester-based inhibitors, and phosphite-based inhibitors. The amount of reaction inhibitor added is usually 0.001 to 5 mass% of the total thermally conductive organopolysiloxane composition. In particular, for the purpose of improving the handling properties of the present composition, acetylene compounds such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-phenyl-1-butyn-3-ol (=phenylbutynol); eneyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; cycloalkenylsiloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; methyltris-1,1-dimethyl-2-propynyloxysilane; and triazole compounds such as benzotriazole can be used without particular limitation.

[0086] [Adhesion Imparting Agent] The composition of the present invention may further contain an adhesion imparting agent for the purpose of improving the adhesive strength of the cured product and the permanent adhesion to substrates. The adhesion imparting agent usable in the present invention may be one or more selected from conventionally known adhesion imparting agents, such as reaction mixtures of amino group-containing organoalkoxysilanes and epoxy group-containing organoalkoxysilanes (including carbasilatrane derivatives and silatrane derivatives having specific structures), organic compounds having two or more alkoxysilyl groups in the molecule, such as disilaalkane compounds (e.g., 1,6-bis(trimethoxysilyl)hexane), and epoxy group-containing silanes or partial hydrolysis condensates thereof. Two or more adhesion imparting agents selected from these may also be used in combination, and this is preferred.

[0087] Preferably, the tackifier is represented by the general formula (L-1):ａ ｎ Si(OR ｂ ) ４－ｎ (In the formula, R ａ is a monovalent epoxy group-containing organic group, and R ｂ is an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. n is a number ranging from 1 to 3), and (L-2) an organic compound having at least two alkoxysilyl groups per molecule and containing a bond other than a silicon-oxygen bond between the silyl groups, in a mass ratio of 5:95 to 95:5, preferably 50:50 to 95:5, and more preferably 60:40 to 90:30. While each of these components alone improves the initial adhesion of the organopolysiloxane cured product, using them in combination in the above mass ratio can significantly improve the initial adhesion, adhesion durability, and adhesive strength (permanent adhesion) of the organopolysiloxane cured product.

[0088] Examples of the component (L-1) include 3-glycidoxyprolyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane.

[0089] Examples of the component (L-2) include disilaalkanes such as 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,4-bis(trimethoxysilyl)hexane, 1,5-bis(trimethoxysilyl)hexane, 2,5-bis(trimethoxysilyl)hexane, 1-methyldimethoxysilyl-6-trimethoxysilylhexane, 1-phenyldiethoxysilyl-6-triethoxysilylhexane, and 1,6-bis(methyldimethoxysilyl)hexane.

[0090] As an adhesion promoter other than the above components (L-1) and (L-2), a reaction mixture of an amino group-containing organoalkoxysilane and an epoxy group-containing organoalkoxysilane (including carbasilatrane derivatives and silatrane derivatives having specific structures), as disclosed in JP-B No. 52-8854 and JP-A No. 10-195085, may also be used in combination.

[0091] [Organic Solvents and Other Additives] In addition to the components described above, the thermally conductive composition of the present invention can contain optional components within the scope of the present invention. Examples of optional components include cold resistance imparting agents, flame retardant imparting agents, pigments, dyes, etc. Furthermore, the thermally conductive composition of the present invention can optionally contain one or more antistatic agents such as known surfactants; dielectric fillers; electrically conductive fillers; release components; thixotropic agents; antifungal agents, etc. Furthermore, an organic solvent may be added as desired.

[0092] [Production Method and Formulation of Composition] The thermally conductive composition of the present invention can be prepared by mixing the above-mentioned components. Examples of the mixing device include the same devices as those exemplified for the surface treatment of the filler. As mentioned above, component (G) may be added after the surface treatment / base heat of the filler, or together with the surface treatment agent for the filler. Regardless of the timing of addition, the technical effects of the present invention can be achieved. More specifically, the composition of the present invention is preferably produced by one of the following production methods (mixing processes): i) a production method comprising a step of mixing the above-mentioned component (A), a filler containing component (B), and a surface treatment agent containing component (C), followed by a step of heating and mixing the mixture, and then optionally mixing component (G) and other components; or ii) a production method comprising a step of mixing the above-mentioned component (A), a filler containing component (B), optionally component (G), and a filler containing component (B) containing component (C) and component (B), followed by a step of heating and mixing the mixture, and then mixing other components. The heating conditions are the same as the base heat conditions described above in the surface treatment of the filler, and it is preferable to mix the ingredients so that the whole is substantially uniform.

[0093] The thermally conductive composition of the present invention may be a one-component composition, optionally containing the hydrosilylation reaction inhibitor and other components, or a multi-component composition consisting of two or more components stored separately. Multi-component compositions must not simultaneously contain component (A), including component (A2), component (D), and component (E). This is because combining these components (base, crosslinker, and catalyst) simultaneously can spontaneously initiate a crosslinking reaction, resulting in a loss of storage stability within a short period of time, potentially preventing the long-term storage stability and ease of handling that are the objectives of multi-component compositions. When used, multi-component compositions are mechanically stirred in a common container using a mixer or other device, or mixed using a dispenser designed for mixing multiple components, and then applied or coated.

[0094] The thermally conductive composition of the present invention has extremely high thermal conductivity, and its cured product exhibits excellent flexibility and stress relaxation properties. It can be easily extruded from a cartridge or dispenser, and has excellent workability, filling properties, and applicability. Therefore, even when filled into a small-scale syringe, such as a syringe with a volume of approximately 10 to 300 ml, the composition has the advantage of being easily applied to a heat-dissipating area and extruding easily. Therefore, the composition is easily filled into a small-scale cartridge or syringe, and is easily applicable to small-scale package production. In particular, the thermally conductive composition of the present invention contains component (C), a macromonomer-type treatment agent having a specific degree of siloxane polymerization, which improves its extrusion workability, making it particularly suitable for small-scale package production.

[0095] [Use of Non-Cured / Uncured Composition] The thermally conductive composition of the present invention can be applied in an uncured or uncured state to a heat dissipation component or a circuit board on which the heat dissipation component is mounted, to obtain a heat dissipation structure comprising an uncured heat dissipation member (examples of which include thermal dissipation grease and uncured thermally conductive gap filler material).

[0096] [Curability] When at least a portion of component (A) contains a curing-reactive component (A2), the thermally conductive composition of the present invention cures via a hydrosilylation reaction to form a cured product with excellent thermal conductivity, suppressed hardness change even after heat aging, and excellent flexibility and stress relaxation properties. The temperature conditions for curing this hydrosilylation reaction-curable composition are not particularly limited, but are typically within the range of 20°C to 200°C, preferably 20°C to 150°C, and more preferably 20°C to 80°C. If desired, the composition may be cured at a high temperature for a short period of time, or at a low temperature such as room temperature for a long period of time (e.g., several hours to several days), and are not particularly limited. Furthermore, by selecting a high-energy ray-activated catalyst or a photoactivatable catalyst for at least a portion of component (E), curing may be triggered by irradiation with high-energy rays.

[0097] By using the thermally conductive composition of the present invention, the curable thermally conductive composition can be applied to a heat dissipation component or a circuit board on which the heat dissipation component is mounted, and a cured product can be formed at a temperature in the range of 20°C to 150°C, preferably less than 130°C, for example, 20 to 125°C, to obtain a heat dissipation structure provided with a heat dissipation member.

[0098] [Thermal Conductivity] The thermally conductive composition of the present invention can be stably and highly filled with a thermally conductive filler and has a thermal conductivity of preferably 9.0 W / mK or more, particularly preferably 9.1 W / mK or more. The thermally conductive composition of the present invention can be designed to have a thermal conductivity of 9.0 to 15.0 W / mK, and optionally a thermal conductivity of 9.1 to 14.0 W / mK, and also has excellent workability, such as extrudability and dispensability from a cartridge, etc. Furthermore, the present composition may be either non-curable or curable, and by including component (C), which is a macromonomer-type treatment agent having a specific degree of siloxane polymerization, not only is its extrusion workability and thermal conductivity improved, but when it is curable, its heat aging properties, particularly at high temperatures, are particularly excellent. Furthermore, by using components (F) / (G) (particularly the use of at least one of the phthalocyanine compound, component (F1), and carbon black, component (F2)), changes in hardness are further suppressed even after heat aging, making it possible to realize a thermally conductive cured product with excellent flexibility and stress relaxation properties.

[0099] [Uses and Heat Dissipation Structures] The thermally conductive composition of the present invention and its cured product are useful as heat transfer materials (thermally conductive members) to be interposed at the interface between the thermal boundary surface of a heat-generating component and a heat dissipation member such as a heat sink or circuit board for cooling the heat-generating component by heat conduction, and a heat dissipation structure including the composition can be formed. Here, the type, size, and detailed structure of the heat-generating component are not particularly limited. However, the thermally conductive composition of the present invention or a cured product obtained by curing the composition has high thermal conductivity and excellent initial adhesion and adhesive strength to the component. Furthermore, it suppresses hardness change over a long period of time, even after heat aging, and maintains flexibility and stress relaxation properties. Therefore, it is less likely to peel off from the heat-generating component or form voids due to vibration, etc., has high adhesion and conformability, and is highly industrially productive. Therefore, it is suitable for use in heat dissipation structures for automobile parts, electrical and electronic components, and electrical and electronic devices, including cell-type secondary batteries.

[0100] The structure of such a heat dissipation structure is not particularly limited, but an example is a heat dissipation structure in which a heat dissipation member is provided on a heat dissipation component or a circuit board on which the heat dissipation component is mounted, via the thermally conductive composition or a cured product thereof. An example of such a structure is a structure in which an electronic component, which is a heat dissipation component, is mounted on a circuit board, and heat generated from the electronic component is dissipated by the heat dissipation member via a thin film layer of the thermally conductive composition or a cured product thereof. These components exhibit small changes in hardness after heat aging, which is a feature of the present invention, maintain the flexibility and stress relaxation properties of the heat dissipation component, and have excellent adhesion and conformability, so they may be suitably arranged not only on horizontal surfaces but also on inclined or vertical surfaces.

[0101] In such a heat dissipation structure, the thickness of the thermally conductive composition or its cured product is not particularly limited, but may be in the range of 0.1 to 100 mm, and heat generated from an electronic component filled with the composition or its cured product without gaps can be efficiently conducted to the heat dissipation member.

[0102] Electrical and electronic devices equipped with members made from the thermally conductive composition are not particularly limited, and examples thereof include secondary batteries such as cell-type lithium-ion electrode secondary batteries and cell-stack type fuel cells; electronic circuit boards such as printed circuit boards; IC chips packaged with optical semiconductor elements such as diodes (LEDs), organic electroluminescent devices (organic EL), laser diodes, and LED arrays; CPUs used in electronic devices such as personal computers, digital video disks, mobile phones, and smartphones; and LSI chips such as driver ICs and memories. In particular, in high-performance digital switching circuits formed with high integration density, heat removal (heat dissipation) is a key factor in the performance and reliability of integrated circuits. Thermally conductive members made using the thermally conductive organopolysiloxane composition of the present invention have excellent heat dissipation properties and handling properties even when applied to power semiconductor applications such as engine control, powertrain systems, and air conditioning control in transportation vehicles. They maintain strong adhesion to components and achieve excellent heat resistance and thermal conductivity even when incorporated into on-board electronic components such as electronic control units (ECUs) and used in harsh environments.

[0103] The present invention will be described below with reference to examples, but the present invention is not limited to these. In the examples and comparative examples shown below, the following compounds or compositions were used as raw materials. The average particle size of the thermally conductive filler is the cumulative average particle size D50 (median size) in the volume-based particle size distribution measured by the laser diffraction scattering method, and the coarse particle content (volume %) measured by the same method is specified.

[0104] [Preparation of Composition and Production of Thermally Conductive Organopolysiloxane Cured Product (Evaluation Sample)] The components were mixed as described below to obtain thermally conductive compositions of Examples and Comparative Examples (hereinafter sometimes referred to as "thermally conductive organopolysiloxane compositions"). The thermally conductive organopolysiloxane compositions were filled into a mold measuring 6 mm in height, 50 mm in length, and 30 mm in width, and cured at 80°C for 30 minutes. The composition was then removed from the mold to obtain a thermally conductive organopolysiloxane cured product. The hardness of the obtained thermally conductive organopolysiloxane cured product was measured using the following method.

[0105] [Hardness (Type E Hardness)] Two sheets of the thermally conductive organopolysiloxane cured product obtained under the above conditions were stacked on top of each other, and the hardness was measured after 3 seconds using an ASKER TYPE E hardness tester manufactured by ASKER Corporation. [Thermal Conductivity] Two sheets of the thermally conductive organopolysiloxane cured product obtained under the above conditions were used to measure thermal conductivity using a TPS-500 (hot disc method) manufactured by Kyoto Electronics Manufacturing Co., Ltd. [Hardness / Thermal Conductivity Change] The hardness change was calculated from the initial hardness of the thermally conductive organopolysiloxane cured product obtained under the above conditions and the hardness of the same cured product after aging in a 150°C oven for 100 hours. The thermal conductivity change was calculated from the initial thermal conductivity of the thermally conductive organopolysiloxane cured product obtained under the above conditions and the thermal conductivity of the same cured product after aging in a 150°C oven for 100 hours. When voids are generated inside due to aging, the thermal conductivity decreases, and it can be determined that internal foaming or cracks have occurred. [Extrusion amount] The extrusion amount was measured by filling a 30 cc EFD syringe (manufactured by Nordson Corporation) with the thermally conductive composition and extruding it at an extrusion pressure of 80 psi, and measuring the extrusion weight per minute.

[0106] The composition of the present invention is formed from the following components: Component (C): C-1: a compound of the formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ４０ Si(OCH ３ ) ３ C-2: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ５０ Si(OCH ３ ) ３ C-3: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ６０ Si(OCH ３ ) ３ C-4: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ７０ Si(OCH ３ ) ３ C-5: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ８０ Si(OCH ３ ) ３ C-6: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ９０ Si(OCH ３ ) ３ Non-C-1: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ３０ Si(OCH ３ ) ３ Non-C-2: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO １００ Si(OCH ３ )３ Non-C-3: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO １１０ Si(OCH ３ ) ３ Organopolysiloxane (= macromonomer type treatment agent) represented by the formula:

[0107] Component (B): B-1: Irregular zinc oxide powder having an average particle size of 0.12 μm B-2: Polyhedral spherical α-type aluminum oxide powder having an average particle size of 2 μm B-3: Irregular aluminum nitride powder having an average particle size of 18.5 μm B-4: Irregular aluminum nitride powder having an average particle size of 100 μm B-5: Spherical magnesium oxide powder having an average particle size of 120 μm Component (A): A-1: ​​Dimethylpolysiloxane capped at both molecular chain ends with dimethylvinylsiloxy groups (molecular weight dispersity 1.14, number average molecular weight 3890, Vi content 2.13% by mass)

[0108] Component (D): D-1: Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, with an average of two groups per molecule and two groups on the side chains (viscosity 20 mPa·s, Si—H content 0.10% by mass). D-2: Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, with an average of three groups per molecule and three groups on the side chains (viscosity 12 mPa·s, Si—H content 0.21% by mass).

[0109] Component (E): E-1: A complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane having a platinum concentration of 5200 ppm

[0110] Component (H): H-1: methyltris-1,1-dimethyl-2-propynyloxysilane Component (F): F-1: 29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32 copper

[0111] Other ingredients: Component (C'-1): Decyltrimethoxysilane Component (G-1): Calcium stearate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0112] Example 1 1.00 parts by mass of component (C-1), 2.31 parts by mass of component (A-1), 0.78 parts by mass of component (D-1), 0.120 parts by mass of component (D-2), 0.20 parts by mass of component (C"-1), and 0.10 parts by mass of component G-1 were weighed, and 14.28 parts by mass of component (B-1), 28.0 parts by mass of component (B-2), 19.0 parts by mass of component (B-3), 18.5 parts by mass of component (B-4), and 15.5 parts by mass of component (B-5) were sequentially mixed thereto over a period of 60 minutes. After homogenization, the mixture was heated and mixed at 160°C under reduced pressure for 60 minutes, and then cooled to room temperature to obtain a mixture. 0.001 parts by mass of component (H-1) and 0.053 parts by mass of component (F-1) were homogenized into this mixture. Subsequently, 0.06 parts by mass of component (E-1) was added and mixed uniformly to obtain a thermally conductive silicone composition. Note that a T.K.HIVIS MIX (model number) mixer manufactured by TOKUSHU KIKA KOGYO CO., LTD. was used as the mixing device for each of the examples and comparative examples of the present invention.

[0113] Example 2: A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 parts by mass of component (C-1) in Example 1 was replaced with 1.00 parts by mass of component (C-2). Example 3: A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 parts by mass of component (C-1) in Example 1 was replaced with 1.00 parts by mass of component (C-3). Example 4: A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 parts by mass of component (C-1) in Example 1 was replaced with 1.00 parts by mass of component (C-4). Example 5: A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 parts by mass of component (C-1) in Example 1 was replaced with 1.00 parts by mass of component (C-5). Example 6: A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 parts by mass of component (C-1) in Example 1 was replaced with 1.00 parts by mass of component (C-6).

[0114] [Comparative Example 1] A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 part by mass of component (C-1) in Example 1 was replaced with 1.00 part by mass of component (non-C-1). [Comparative Example 2] A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 part by mass of component (C-1) in Example 1 was replaced with 1.00 part by mass of component (non-C-2). [Comparative Example 3] A thermally conductive silicone composition was obtained in the same manner as in Example 1, except that 1.00 part by mass of component (C-1) in Example 1 was replaced with 1.00 part by mass of component (non-C-3).

[0115] For the thermally conductive organopolysiloxane compositions of Examples 1 to 6, the composition, extrusion amount, hardness, thermal conductivity, and changes in hardness and thermal conductivity after heat aging of the resulting cured thermally conductive organopolysiloxane products are shown in Table 1. For the thermally conductive organopolysiloxane compositions of Comparative Examples 1 to 3, the composition, extrusion amount, hardness, thermal conductivity, and changes in hardness and thermal conductivity after heat aging of the resulting cured thermally conductive organopolysiloxane products are shown in Table 2.

[0116]

[0117]

[0118] As shown in Table 1, the thermally conductive silicone compositions of Examples 1 to 6, which used a macromonomer-type treating agent with a degree of polymerization within the specified range as component (C) according to the present invention, exhibited thermal conductivities exceeding 10 W / m K and extrusion rates exceeding 40 g / min, demonstrating good workability. Furthermore, the hardness change of the cured products after aging at 150°C for 100 hours was 20 points or less, the stress relaxation properties and flexibility of the cured products were not impaired, the thermal conductivity was positive, and there was no decrease in thermal conductivity (heat dissipation performance) even after heat aging.

[0119] On the other hand, as shown in Table 2, the thermally conductive silicone composition of Comparative Example 1, which used a macromonomer-type treatment agent with a degree of polymerization below the specified range instead of component (C) of the present invention, exhibited a thermal conductivity of over 10 W / m K and an extrusion rate of over 40 g / min, demonstrating good workability. However, the hardness of the cured product after aging at 150°C for 100 hours changed by more than 20 points, impairing the stress relaxation properties and flexibility of the cured product. Furthermore, the thermal conductivity was negative, indicating a decrease in thermal conductivity (i.e., heat dissipation performance) after heat aging.

[0120] Furthermore, the thermally conductive silicone compositions of Comparative Examples 2 and 3, which used a macromonomer-type treatment agent with a degree of polymerization above the specified range instead of component (C) according to the present invention, exhibited a thermal conductivity of over 10 W / m K, but the extrusion rate did not reach 40 g / min, resulting in clearly inferior extrusion workability compared to the Examples.

[0121] [Summary] The results of Examples 1 to 6 indicate that the thermally conductive organopolysiloxane composition using components (A) to (C) of the present invention can achieve a high thermal conductivity of 10 W / m K or more and good extrusion workability with an extrusion rate of more than 40 g / min, and the cured reaction product shows little change in hardness and thermal conductivity even when subjected to high-temperature thermal aging at 150°C for 100 hours. Therefore, it is expected that the composition will maintain good stress relaxation properties, flexibility, and thermal conductivity, and will be able to maintain stable thermal conduction performance / heat dissipation performance even when used at high temperatures for long periods of time.

[0122] On the other hand, the results of Comparative Examples 1 to 3 show that when a macromonomer-type treatment agent having a degree of polymerization outside the specified range is used instead of component (C) according to the present invention, sufficient extrusion workability cannot be achieved, the amount of change in hardness during high-temperature heat aging is large, and the thermal conductivity may decrease. There is a strong concern that use at high temperatures for a long period of time may cause deterioration or cracking, or that stable thermal conductivity / heat dissipation performance may not be maintained.

Claims

1. (A) one or more matrix polymers having a viscosity at 25°C in the range of 10 to 1,000,000 mPa·s; (B) one or more thermally conductive fillers; (C) a compound represented by the general formula (1): (In the formula, R 1 are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bonds, R ２ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, a is a number from 40 to 90, and b is a number from 1 to 3; and the content of component (B) is in the range of 60 to 95 volume % based on the total solid content of the composition.

2. The thermally conductive composition according to claim 1, wherein component (A) is (A0) one or more organopolysiloxanes having a viscosity at 25°C in the range of 10 to 1,000,000 mPa·s.

3. The thermally conductive composition according to claim 1, wherein component (A) is one or more organopolysiloxanes selected from (A1) organopolysiloxanes having no curing reactive groups having carbon-carbon double bonds in the molecule and (A2) organopolysiloxanes having curing reactive groups having carbon-carbon double bonds in the molecule.

4. The thermally conductive composition according to claim 1, wherein component (A) contains at least (A2) an organopolysiloxane having a curing reactive group having a carbon-carbon double bond in the molecule, and also contains (D) an organohydrogenpolysiloxane in an amount such that there are 0.2 to 5 moles of silicon-bonded hydrogen atoms in component (D) per mole of the curing reactive group having a carbon-carbon double bond contained in component (A), and (E) a catalytic amount of a hydrosilylation reaction catalyst.

5. Furthermore, (C') general formula (2): R alk R ３ ２ SiO(R ３ ２ SiO) ｃ R ３ ２ Si-R ４ -SiR ３ (3-ｄ) (OR ５ ) ｄ (In the formula, R alk is an alkenyl group, R ３ are independently unsubstituted or substituted monovalent hydrocarbon groups having no carbon-carbon double bonds, R ４ is an oxygen atom or a divalent hydrocarbon group, R ５ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, c is an integer from 1 to 250, and d is an integer from 1 to 3.) and has a viscosity at 25°C in the range of 10 to 10,000 mPa·s, and has an alkenyl group and a hydrolyzable silyl group at a molecular chain terminal; and (C") an alkoxysilane having an alkyl group having 6 or more carbon atoms in the molecule, or a hydrolyzed condensate thereof.

6. The thermally conductive composition according to claim 1, further comprising (F) a heat resistance imparting agent.

7. The thermally conductive composition according to claim 6, wherein said component (F) is a heat resistance imparting agent at least partially containing a component selected from (F1) a phthalocyanine compound and (F2) carbon black.

8. The thermally conductive composition according to claim 1, further comprising (G) at least one selected from the group consisting of fatty acids, fatty acid esters and fatty acid metal salts.

9. The thermally conductive composition according to claim 8, wherein the component (G) is (G1) one or more members selected from the group consisting of stearic acid, alkali metal salts of stearic acid, and alkaline earth metal salts of stearic acid.

10. The thermally conductive composition according to claim 1, wherein said component (B) is one or more thermally conductive fillers selected from the group consisting of zinc oxide powder, aluminum oxide powder and aluminum nitride powder.

11. A thermally conductive composition according to any one of claims 1 to 10, wherein the composition or a cured reaction product thereof has a thermal conductivity of 9.0 W / mK or more.

12. A thermally conductive member comprising the thermally conductive composition according to any one of claims 1 to 10 or a cured reaction product thereof.

13. A heat dissipation structure comprising the thermally conductive member according to claim 12.

14. A heat dissipation structure comprising a heat dissipation member provided on a heat dissipation component or a circuit board carrying said heat dissipation component via the thermally conductive composition according to any one of claims 1 to 10 or a cured product thereof.

15. The heat dissipation structure according to claim 13 or 14, which is an electric / electronic device.

16. The heat dissipation structure according to claim 13 or 14, which is an electric / electronic component or a secondary battery.

17. A method for producing a thermally conductive composition according to any one of claims 1 to 10, comprising a step of mixing components including at least the components (A) to (C), heating and mixing the mixture, and then a step of mixing other components.

18. A method for producing a heat dissipation structure, comprising the steps of applying the thermally conductive composition according to any one of claims 1 to 10 to a heat dissipation component or a circuit board carrying the heat dissipation component, and curing the composition at a temperature of less than 130°C.

19. A method for using a thermally conductive composition according to any one of claims 1 to 10, comprising filling the thermally conductive composition into a package selected from a syringe, a cartridge and a dispenser having a capacity of 10 to 300 ml, and extruding the composition from the package to apply it to a heat dissipation site.

Images