Thermally conductive composition, thermally conductive member, and heat-dissipating structure

Abstract

[Problem] To provide: a thermally conductive composition which has extremely high thermal conductivity and exhibits excellent extrusion workability, fillability in small packages, and so forth; a thermally conductive member comprising same; and a heat-dissipating structure obtained using same. [Solution] Provided is a thermally conductive composition which is characterized by containing (A) a zinc oxide powder / aluminum oxide powder having a particle size of 0.1-1.0 µm, (B) an amorphous aluminum nitride powder / aluminum oxide powder having a particle size of 2.0-29 µm, (C) an amorphous aluminum nitride powder having a particle size of 30 µm or more, (D) a spherical aluminum nitride powder having a particle size of more than 50 µm, (E) a specific Si-based surface treatment agent, and (F) a matrix polymer. The thermally conductive composition is also characterized in that the content of components (A) to (D) falls within the range 60-90 vol%, with the content of component (C) falling within the range 1.0-20.0 vol% and with the content of component (D) falling within the range 0.0-30.0 vol%, each relative to the total amount of solid content in the composition. Also provided is a use of said 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, and has good extrudability and dischargeability from cartridges, etc., and is easy to fill into small-quantity packages and has excellent work efficiency during application; 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, their cured products are rubbery, thereby maintaining a certain degree of flexibility and stress relaxation properties. This allows them to maintain the heat-dissipating properties of heat-dissipating structures, maintaining their ability to follow and adhere to the heat source. In recent years, thermally conductive silicone compositions filled with large amounts of thermally conductive fillers have been proposed to accommodate high heat dissipation rates. However, thermally conductive fillers such as aluminum oxide and aluminum hydroxide powder have limited thermal conductivity, and even when blended in large amounts, the thermal conductivity of the composition and its cured product cannot be further improved. On the other hand, boron nitride powder is known as a thermally conductive filler with excellent thermal conductivity (see, for example, Patent Document 1, etc.). However, boron nitride powder has a flat shape, and the thermal conductivity of the cured product may become anisotropic.

[0003] In contrast, aluminum nitride powder is known as a thermally conductive filler that also exhibits excellent thermal conductivity. Aluminum nitride powder is known to be spherical or irregular in shape, and, unlike boron nitride powder, is less likely to produce anisotropy in the thermal conductivity of the cured product. Therefore, thermally conductive silicone compositions have been proposed that combine various aluminum nitride powders and other thermally conductive fillers (Patent Documents 2 to 19).

[0004] 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.

[0005] None of the above documents describes or suggests further adjusting the hardness of a cured product in a hydrosilylation reaction-curable silicone composition by blending a fatty acid or the like, or using a phthalocyanine compound or other heat resistance-imparting agent in combination. Patent Document 20 also proposes using a methylpolysiloxane containing a trifunctional hydrolyzable group at one end in a thermally conductive silicone rubber composition for the purpose of adjusting the viscosity and plasticity of the composition, but only those with a degree of polymerization of about 30 are used, and there is no description or suggestion of limiting the degree of polymerization to a specific range, or in particular of the effects on extrusion workability or the heat aging properties and thermal conductivity of the cured product.

[0006] Japanese Patent Application Laid-Open No. 07-330927 International Publication No. 2018 / 016566 Pamphlet (Patent Registration 6246986) Japanese Patent Application Laid-Open No. 2001-002830 (Patent Registration 3746915) Japanese Patent Application Laid-Open No. 2002-299533 (Patent Registration 4574885) Japanese Patent Application Laid-Open No. 2001-230353 (Patent Registration 4357064) Japanese Patent Application Laid-Open No. 2000-063872 (Patent Registration 2930298) International Publication No. 2016 / 190189 Pamphlet International Publication No. 2020 / 262449 Pamphlet International Publication No. 2018 / 074247 Pamphlet International Publication No. 2017 / 2 No. 03924 Pamphlet International Publication No. 2020 / 137086 Pamphlet Japanese Patent Application Laid-Open No. 2020-169231 (Patent Registration 7027368) International Publication No. 2021 / 131212 Pamphlet International Publication No. 2020 / 137970 Pamphlet Japanese Patent Application Laid-Open No. 2020-090584 Pamphlet International Publication No. 2021 / 225059 Pamphlet International Publication No. 2021 / 099507 Pamphlet International Publication No. 2021 / 256391 Pamphlet International Publication No. 2021 / 261958 Pamphlet Japanese Patent Application Laid-Open No. 2000-256558 (Patent Registration 3543663)

[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 contains a thermally conductive filler such as aluminum nitride powder at a very high volume percentage and therefore has high thermal conductivity, and a thermally conductive member made from the cured product has sufficient flexibility and stress relaxation properties for practical use, and is easy to extrude from a cartridge, dispenser, etc., and is particularly excellent in terms of fillability, workability, and applicability into 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 intensive research, the present inventors have discovered: (A) 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; (B) at least one thermally conductive filler selected from aluminum nitride powder and aluminum oxide powder, having an average particle size in the range of 2.0 to 29 μm, and having an irregular, rounded, and polyhedral shape; (C) aluminum nitride powder, having an average particle size of 30 μm or more, and having an irregular, rounded, and polyhedral shape; (D) aluminum nitride powder, having an average particle size of more than 50 μm, and having a spherical shape; (E) one or more components selected from the following components (E1) to (E3): (E1) 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 an integer of 5 to 250, and b is an integer of 1 to 3.) and have a viscosity at 25°C of 10 to less than 10,000 mPa·s; (E2) an organopolysiloxane represented by 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 ３are 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. (E2) a siloxane compound having an alkenyl group and a hydrolyzable silyl group at the molecular chain terminal, the siloxane compound having a viscosity of 10 to 10,000 mPa·s at 25°C; and (E3) an alkoxysilane having an alkyl group having 6 or more carbon atoms in the molecule, or a hydrolysis condensate thereof; and (F) one or more matrix polymers having a viscosity of 10 to 100,000 mPa·s at 25°C, wherein the content of the thermally conductive filler containing components (A) to (D) is in the range of 60 to 90% by volume, based on the total solid content of the composition; the content of component (C) is in the range of 1.0 to 20.0% by volume, based on the total solid content of the composition; and the content of component (D) is in the range of 0.0 to 30.0% by volume, based on the total solid content of the composition. That is, the composition is a thermally conductive composition containing a large amount of a thermally conductive filler such as aluminum nitride powder (specifically, in the range of 60 to 90 volume % of the total solid content of the composition) to impart high thermal conductivity. However, by combining and blending thermally conductive fillers of specific shapes and particle sizes in a specific quantitative range and including a specific component (E) that functions as a surface treatment agent, it is possible to achieve both extremely high thermal conductivity and coatability and workability during extrusion of the composition itself, which have traditionally been in a trade-off relationship, and if the composition is curable, its flexibility (= rubber physical properties) can also be achieved. Note that the thermally conductive filler containing the above components (A) to (D) is substantially free of aluminum nitride powder having an average particle size of less than 2.0 μm (more specifically, the content of aluminum nitride powder having an average particle size of less than 2.0 μm in the entire thermally conductive filler is less than 0.5 mass %, more preferably less than 0.1 mass %, and particularly preferably below the detection limit (= 0.0 mass %)).

[0010] The composition may further contain a certain amount of at least one fatty acid compound selected from fatty acids, fatty acid esters, and fatty acid metal salts, and a heat resistance imparting agent. When preparing the composition, the matrix polymer (preferably an organopolysiloxane) that is the main component of the composition, the thermally conductive filler, and a component that functions as a specific surface treatment agent (the aforementioned component (E)) may be mixed together and heated (base heat), or the matrix polymer (preferably an organopolysiloxane), the thermally conductive filler, and component (E) 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 an extremely high thermal conductivity of 9.0 W / mK or more and yet has practically sufficient coatability, flexibility, and stress relaxation properties, and a thermally conductive member made from the composition, and which can be easily extruded from a cartridge, dispenser, etc., and can be relatively easily filled into small-volume packages such as syringes, resulting in excellent workability and coatability. 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 electric and electronic devices, including a heat dissipation structure for electric and electronic components and a heat dissipation structure for secondary batteries).

[0012] The cured product of the thermally conductive composition of the present invention, optionally containing the fatty acid-based compound and heat resistance additive, not only exhibits extremely high thermal conductivity but also exhibits reduced hardness change even when used at high temperatures. This prevents deterioration of the cured rubber's physical properties and maintains excellent flexibility and stress relaxation properties even after heat aging. When applied to heat dissipation targets of various shapes, it is resistant to peeling or voids (including voids caused by partial or temporary peeling from the target) due to vibration, etc., even when used for long periods at high temperatures. It maintains excellent adhesion and conformability, maintaining initial heat dissipation efficiency without loss. Therefore, compared to conventional products, it offers superior extrusion efficiency, heat dissipation component durability, and heat dissipation performance. It can be applied to heat dissipation targets of various shapes, is resistant to peeling even when used in high-temperature assembly, and is suitable for long-term heat dissipation processes at high temperatures.

[0013] [Thermal Conductive Composition] The composition of the present invention is a thermally conductive composition containing a matrix polymer, preferably an organopolysiloxane, and includes a specific thermally conductive filler in combination with a specific component functioning as a surface treatment agent. By specifying the quantitative range of the thermally conductive fillers, the composition exhibits extremely high thermal conductivity and rubber physical properties in the cured product. It also exhibits excellent workability and application efficiency, and is easily extruded from cartridges or dispensers, allowing for small-volume packaging with excellent fillability. Furthermore, the composition of the present invention may be used in its uncured state as a grease or gap filler material. It may also be a hydrosilylation-curable composition with a defined SiH / alkenyl group reactivity. When the composition is curable, it may contain 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. The inclusion of these components provides the advantage that the rubber physical properties of the cured product are not impaired even after heat aging. Furthermore, in order to further improve the extrusion workability of the composition and the heat aging properties and thermal conductivity of the cured product, a component having a specific degree of siloxane polymerization may be selectively used as component (E1) described below.

[0014] More specifically, the composition according to the present invention comprises: (A) 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; (B) at least one thermally conductive filler selected from aluminum nitride powder and aluminum oxide powder, having an average particle size in the range of 2.0 to 29 μm, and having an irregular, rounded, and polyhedral shape; (C) aluminum nitride powder, having an average particle size of 30.0 μm or more, and having an irregular, rounded, and polyhedral shape; (D) aluminum nitride powder, having an average particle size of more than 50 μm, and having a spherical shape; (E) one or more components selected from the following components (E1) to (E3): (E1) 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 ２are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, or an acyl group, a is an integer of 5 to 250, and b is an integer of 1 to 3.) and have a viscosity at 25°C of 10 to less than 10,000 mPa·s; (E2) an organopolysiloxane represented by 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 ５are 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. (E1) a siloxane compound having an alkenyl group and a hydrolyzable silyl group at the molecular chain terminal, the viscosity of which is in the range of 10 to 10,000 mPa·s at 25°C; and (E2) an alkoxysilane having an alkyl group with 6 or more carbon atoms in the molecule, or a hydrolysis condensate thereof. (F) one or more matrix polymers having a viscosity of 10 to 1,000,000 mPa·s at 25°C. The thermally conductive filler containing components (A) to (D) is contained in an amount ranging from 60 to 90% by volume based on the total solid content of the composition. The content of component (C) is in an amount ranging from 1.0 to 20.0% by volume based on the total solid content of the composition. The content of component (D) is in an amount ranging from 0.0 to 30.0% by volume based on the total solid content of the composition. The composition may be used in an uncured state or may be curable. Specifically, component (F) preferably contains (F0) one or more organopolysiloxanes having a viscosity at 25°C in the range of 10 to 1,000,000 mPa·s. These organopolysiloxanes may be one or more organopolysiloxanes selected from (F1) organopolysiloxanes without a curing reactive group having a carbon-carbon double bond in the molecule and (F2) organopolysiloxanes with a curing reactive group having a carbon-carbon double bond in the molecule. A curing reactive composition using component (F2) may further contain (G) an organohydrogenpolysiloxane and (H) a catalytic amount of a hydrosilylation reaction catalyst, and may optionally contain (K) a heat resistance imparting agent and (J) a fatty acid compound. Furthermore, the composition may 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 explained below.

[0015] Hereinafter, the average particle diameter of each component (including spherical and irregular shapes) of the thermally conductive filler is the cumulative average particle diameter D in the volume-based particle size distribution measured by the laser diffraction scattering method. ５０This is the median diameter, and can be measured using a laser diffraction particle size distribution analyzer that is widely used in the field. Based on this principle, the content (volume %) of coarse particles with a certain particle size or less can be determined using a laser diffraction particle size distribution analyzer.

[0016] [Thermal Conductive Fillers (A) to (D)] Components (A) to (D) are thermally conductive fillers that impart thermal conductivity to the composition and the thermally conductive member obtained by curing the composition. In the present invention, these thermally conductive fillers (including individual components) preferably do not substantially contain aluminum nitride powder having an average particle size of less than 2.0 μm (hereinafter sometimes referred to as "coarse particles") in order to achieve the technical effects of the present invention. Here, "substantially free" means that the content of aluminum nitride powder having an average particle size of less than 2.0 μm in the entire thermally conductive filler is less than 0.5% by volume, more preferably less than 0.1% by volume, and particularly preferably below the detection limit (=0.0% by volume). On the other hand, if any of components (A) to (D) or other thermally conductive fillers contains 0.5% by 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 achieved.

[0017] Component (A) 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.

[0018] Component (A) 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 and workability during extrusion.

[0019] Component (B) is an aluminum nitride powder or aluminum oxide powder having an average particle size in the range of 2.0 to 29 μm and selected from amorphous, rounded, and polyhedral shapes. The shape of component (B) 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 (B). 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 appearance, 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 (B) 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 (B) 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 (B) is different or the particle size is below the lower limit, workability, particularly during extrusion, may be impaired, or a paste-like composition may not be obtained in the first place, making extrusion from a cartridge or dispenser difficult.

[0020] Component (C) is an aluminum nitride powder having an average particle size of 30 μm or more and selected from amorphous, rounded, and polyhedral shapes, and when used in combination with components (A) and (B) in a certain quantitative range, it achieves the technical effects of the present invention and achieves very high thermal conductivity without causing any anisotropy problems. Note that it is separated from component (B) by the upper limit of its average particle size.

[0021] The shape of component (C) 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 component (C) having these shapes can be clearly distinguished from symmetrical spherical or polyhedral spherical particles. In the present invention, the most suitable component (C) 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, component (D), which will be described later, can be used in combination as a large-particle-size, spherical aluminum nitride powder, and this is preferred.

[0022] The average particle size of component (C) 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 (C) preferably does not contain aluminum nitride powder with an average particle size of less than 2.0 μm, and component (C) containing such particles in an amount 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 (C) 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.

[0023] Component (D) 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, when used in combination with components (A), (B), and (C) in a certain quantitative range, it further improves the technical effects of the present invention and achieves extremely high thermal conductivity without causing any anisotropy problems. Note that it is distinguished from component (B) by the upper limit of its average particle size, and from component (C) by its shape.

[0024] The average particle size of component (D) 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 (D) preferably does not contain aluminum nitride powder having an average particle size of less than 2.0 μm, and component (D) containing such particles in an amount of 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 described for component (C).

[0025] [Other Thermally Conductive Fillers] The composition of the present invention may contain thermally conductive fillers other than the above components (A) to (D). For example, the fillers may be 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, which do not fall under components (A) to (D). Metal-based powders, metal oxide-based powders, metal nitride-based powders, and carbon powders are preferred. The shape of the fillers is not particularly limited, but examples include spherical, acicular, disc-like, rod-like, and irregular shapes. Spherical and irregular shapes are preferred. As long as the above requirements for components (A) to (D) and their quantitative ranges are met, the average particle size of the other thermally conductive fillers is not particularly limited, but is preferably in the range of 0.01 to 500 μm, more preferably 0.01 to 300 μm.

[0026] The other thermally conductive filler is preferably silver powder, aluminum powder, aluminum oxide powder, zinc oxide powder, magnesium oxide powder, aluminum nitride powder, or graphite. Furthermore, when electrical insulation is required for the composition, a metal oxide powder or metal nitride powder is preferred, and aluminum oxide powder, zinc oxide powder, magnesium oxide powder, or aluminum nitride powder is particularly preferred, except for those corresponding to components (A) to (D).

[0027] [Amounts of Components (A) to (D) and Other Thermally Conductive Fillers] The composition of the present invention has an extremely high thermal conductivity of 9.0 W / mK or more, and can be used to 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 amounts of the above components within specific ranges.

[0028] Specifically, in the present invention, to achieve high thermal conductivity, the content of the thermally conductive filler, including components (A) to (D), is in the range of 60 to 90% by volume, preferably 65 to 90% by volume, 70 to 90% by volume, or 75 to 90% 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 (E), 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.

[0029] The sum of the amounts of the thermally conductive fillers including components (A) to (D) used 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 (F) described below. When the amount of the thermally conductive filler used is in the above-mentioned volume percent range and the amount used relative to component (F) satisfies the above-mentioned range, the problem of the present invention can be particularly suitably solved.

[0030] The content of component (C) is in the range of 1.0 to 20.0% by volume, more preferably 2.0 to 20.0% by volume, and more preferably 3.0 to 19.0% by volume, based on the total solid content of the composition.

[0031] 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.

[0032] Furthermore, it is preferable that the content of the amorphous aluminum nitride powder selected from component (B) and component (C) is 50 mass % or less based on the total solid content in the composition.

[0033] 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.

[0034] 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.

[0035] [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 fillers containing components (A) to (D). On the other hand, for the purpose of achieving other functions such as improving (reinforcing) mechanical strength or 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.

[0036] [Component (E)] Component (E) functions as a surface treatment agent for the aforementioned components (A) to (D), other thermally conductive fillers, and other inorganic fillers. It may coexist with these components in the composition. Preferably, components (A) to (D) are surface-treated with at least a portion of component (E), which is particularly preferable from the standpoints of uniform dispersion of these components and the handling and workability of the resulting composition. Component (E) is one or more components selected from siloxane compounds having an alkoxy group at one end (components (E1) and (E2)) and / or alkoxysilanes having a long-chain alkyl group (component (E3)). More specifically, it is one or more components selected from the following components (E1) to (E3). Component (E1) may be used to further improve the extrusion workability of the composition and the heat aging properties and thermal conductivity of the cured product. In particular, component (E1) having a specific degree of siloxane polymerization may be used.

[0037] (E1) 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 an integer of 5 to 250, and b is an integer of 1 to 3, and has a viscosity at 25°C of 10 to less than 10,000 mPa·s.

[0038] In general formula (1), R 1 are 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.

[0039] R ２ are independently a hydrogen atom, an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. ２is preferably an alkyl group, and particularly preferably a methyl group or an ethyl group.

[0040] In general formula (1), a is an integer ranging from 5 to 250, preferably from 10 to 200. Furthermore, b is an integer ranging from 1 to 3, preferably 2 or 3. Component (E1) 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.

[0041] When the siloxane polymerization degree (a) of component (E1) is in the range of 40 to 90, the extrusion workability of the composition and the heat aging properties and thermal conductivity of the cured product can be further improved. Therefore, as an optional configuration of the present invention, at least a portion of component (E) contains component (E1), and component (E1) is preferably an organopolysiloxane represented by general formula (1) in which a is a number in the range of 40 to 90, 45 to 90, 50 to 90, or 50 to 80, and b is 3. Even in the case of an organopolysiloxane represented by general formula (1), if the value of a is not within the above range (for example, if a is 30 or 100), 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 compared to when an organopolysiloxane in which a is within the above range is used as component (E1).

[0042] (E2) 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 ５are 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. A siloxane compound having an alkenyl group and a hydrolyzable silyl group at the molecular chain terminal, and having a viscosity at 25°C in the range of 10 to 10,000 mPa·s.

[0043] In general formula (2), R alk is an alkenyl group, and examples thereof include alkenyl groups having 2 to 10 carbon atoms, such as vinyl, allyl, and hexenyl. Because component (E2) has an alkenyl group at one end of the molecular chain, it may be possible to improve the curability and adhesive properties when used in combination with other crosslinking agents, etc.

[0044] In the formula, R ３ R 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.

[0045] 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 (G2) 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).

[0046] In the formula, c is the degree of polymerization of the diorganosiloxane units of component (E2) (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 (E2) is particularly preferably a trimethoxysilyl group (-Si(OMe) ３ )

[0047] The blending amounts of component (E1) and component (E2) (the total amount when both are used in combination) are not particularly limited as long as they are 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 (F) in the entire composition.

[0048] (E3) An alkoxysilane having an alkyl group having 6 or more carbon atoms in the molecule, or a hydrolysis condensate thereof.

[0049] Like component (E1) or (E2), component (E3) functions as a surface treatment agent for the thermally conductive filler containing components (A) to (D) in the composition, improving the blending amount, improving the viscosity and flowability of the entire composition, and improving the adhesive properties. Such alkoxysilanes must have an alkyl group of 6 or more carbon atoms. When alkylalkoxysilanes containing only alkyl groups of less than 6 carbon atoms, such as methyl groups, or their hydrolysis condensates are used, sufficient adhesive properties may not be achieved, even when an adhesion promoter, as described below, is used in combination.

[0050] 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.

[0051] Preferably, component (E3) 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.

[0052] Specifically, such component (E3) is 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.

[0053] The amount of component (E3) to be blended is not particularly limited as long as it is an amount sufficient for surface treatment of the filler. 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 (F) in the entire composition.

[0054] [Surface Treatment of Thermally Conductive Fillers Containing Components (A) to (D) and Other Inorganic Fillers] In the present invention, components (A) to (D) and other thermally conductive fillers, as well as 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 aforementioned component (E). Furthermore, these fillers may be treated with various surface treatment agents known as coupling agents in addition to these components. Examples of surface treatment agents for treating the fillers of the present invention include, in addition to component (E), surfactants, other silane coupling agents, aluminum-based coupling agents, and silicone-based surface treatment agents.

[0055] The method for surface treating the filler with these components is not particularly limited, and examples thereof 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 part or all of component (F) described below and component (E) are premixed, the filler is sequentially mixed into the mixture, and the mixture is heated (base heat) after homogenization. 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 standpoint of improving the extrusion workability and thermal conductivity of the composition, it may be a stepwise treatment process including a step in which at least a portion of the filler is surface-treated with one or more of component (E) selected from component (E1) and component (E2), and then the filler is surface-treated with component (E3). Note that by using an organopolysiloxane in which component (E) contains component (E1) and in which, in the general formula (1), a is a number in the range of 40 to 90 and b is 3, the extrusion workability of the composition can be particularly suitably improved in some cases.

[0056] 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.

[0057] [(F) Matrix Polymer] Component (F) 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 restrictions. For example, organopolysiloxanes, liquid polyurethane resins, liquid polyester resins, liquid acrylic resins, liquid polyol resins, liquid butadiene rubber, liquid isoprene rubber, and liquid styrene-butadiene rubber can be used without any restrictions. However, since the thermally conductive composition of the present invention is used in semiconductor devices that generate high temperatures, it is particularly preferable to include one or more organopolysiloxanes (F0) with excellent heat and cold resistance and a viscosity at 25°C ranging from 10 to 1,000,000 mPa·s. Note that any component corresponding to the aforementioned component (E) is explicitly excluded from the scope of component (F).

[0058] The organopolysiloxane, component (F0), is the main component of this 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 (F) 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 (F) 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 (F) contain reduced or eliminated low-molecular-weight siloxane oligomers (octamethyltetrasiloxane (D4), decamethylpentasiloxane (D5)).

[0059] Component (F) 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.

[0060] Depending on the presence or absence of a curing reactive group in component (F), 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.

[0061] Preferably, component (F) is one or more organopolysiloxanes selected from (F1) organopolysiloxanes that do not have a curing reactive group that has a carbon-carbon double bond in the molecule and (F2) organopolysiloxanes that have a curing reactive group that has a carbon-carbon double bond in the molecule, and component (F1) alone, component (F2) alone, or both may be used in combination. Note that when component (F2) is used as at least a portion of component (F), the composition can be designed to be curable.

[0062] Component (F1) 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 (F1) 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.

[0063] Particularly preferred examples of component (F1) are linear, non-curable organopolysiloxanes, such as dimethylpolysiloxanes terminally blocked with trimethylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminally blocked with trimethylsiloxy groups, dimethylsiloxane 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 with halogenated alkyl groups such as 3,3,3-trifluoropropyl, and mixtures of two or more of these polymers.

[0064] Component (F2) 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 (F2) 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.

[0065] Examples of alkenyl groups in the molecule of component (F2) include vinyl, allyl, butenyl, and hexenyl groups. Examples of organic groups other than alkenyl groups in component (F2) 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.

[0066] Particularly preferred examples of component (F2) 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 with 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.

[0067] When component (F) includes component (F2), the composition may and preferably includes (G) an organohydrogenpolysiloxane as a curing agent, and (H) a catalytic amount of a hydrosilylation reaction catalyst.

[0068] [(G) Organohydrogenpolysiloxane] Component (G) is the primary crosslinking agent of the composition of the present invention, and any organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per 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 per molecule of the organohydrogenpolysiloxane does not exceed 8. In particular, it is preferable to include at least (G1) 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 per molecule, with at least one of these atoms on average located in a side chain on the molecular chain.

[0069] Examples of such component (G1) 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.

[0070] The viscosity of component (G1) 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.

[0071] [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 (G) in an amount such that the number of silicon-bonded hydrogen atoms in component (G) 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 contained in component (F).

[0072] [(H) 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.

[0073] 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

[0074] 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.

[0075] [(J) 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 changes in hardness 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 range, if component (J) is not used, the cured product may rapidly harden during heat aging, resulting in a loss of its stress relaxation properties, flexibility, and substrate adhesion. However, by using component (J) in combination with a heat resistance-imparting agent, preferably component (K), described below, in the hydrosilylation-curable 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.

[0076] Specifically, component (J) 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 (J) is at least one selected from (J1) saturated fatty acids and saturated fatty acid metal salts, and particularly preferably one or more selected from (J1-1) stearic acid, alkali metal salts of stearic acid, and alkaline earth metal salts of stearic acid.

[0077] Although the mechanism by which component (J) inhibits changes in hardness of the cured product, particularly when used in combination with component (K), has not been clearly identified, 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 (K), 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 (J) 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 (J) to the composition in the present invention is not limited.

[0078] The amount of component (J) is preferably in the range of 0.05 to 2.0 parts by mass per 100 parts by mass of the thermally conductive filler containing the components (A) to (D) (total amount if multiple components are included). In particular, the amount of component (D) must be within the above range to achieve the above technical effect, and this range is critical. That is, if the amount of component (J) is below the above lower limit, even when used in combination with component (K), it may not be possible to suppress changes in hardness of the cured product. On the other hand, if the amount of component (J) exceeds the above upper limit, it may not be possible to suppress changes in hardness of the cured product.

[0079] [(K) 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 blended alone, the composition of the present invention and its cured product can achieve its technical effects by containing a certain amount of the above-mentioned (J) fatty acid compound and using the (K) heat resistance imparting agent in combination. The blending 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).

[0080] 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 (K1) 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 particularly preferred, non-limiting example of a 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 (K2) 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 temperatures of 180°C or higher and the high-temperature heat resistance.

[0081] [(L) Hydrosilylation Reaction Inhibitor, Adhesion Promoter, Organic Solvent, and Other Additives] The composition of the present invention essentially comprises components (A) to (F). When component (F) contains curable component (F2), it preferably further contains components (G) and (H), and more preferably contains one or more selected from component (J) and component (K). It is particularly preferred to use components (J) and (K) in combination. However, the composition may further contain the other components described below. In particular, when the composition is curable, it is particularly preferred to use a hydrosilylation reaction inhibitor.

[0082] [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.

[0083] [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.

[0084] 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.

[0085] Examples of the component (L-1) include 3-glycidoxyprolyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane.

[0086] 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.

[0087] 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.

[0088] [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.

[0089] [Composition Manufacturing Method and Formulation] 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 in the surface treatment of the filler. As mentioned above, component (J) may be added after the surface treatment / base heat of the filler, or together with the surface treatment agent for the filler. The technical effects of the present invention can be achieved regardless of the timing of addition. More specifically, the composition of the present invention is preferably produced by one of the following manufacturing methods (mixing processes): i) a manufacturing method comprising a step of mixing component (F), filler, and component (E), followed by a step of heat-mixing the mixture, and then optionally mixing component (J) and other components; or ii) a manufacturing method comprising a step of mixing component (F), filler, and optionally component (J), and component (E), followed by a step of heat-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 entire mixture so that it is substantially uniform.

[0090] 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 (F), including component (F2), component (G), and component (H). This is because combining these components (main component, 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.

[0091] 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, exhibiting excellent workability, fillability, 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 advantages of excellent application and extrusion operability to a heat-dissipating site. Therefore, the composition is easily filled into a small-scale cartridge or syringe, making it suitable for small-scale package production. In particular, when the thermally conductive composition of the present invention contains component (E1) as component (E) and uses an organopolysiloxane having the general formula (1) in which a is a number in the range of 40 to 90 and b is 3, the extrusion operability can be further improved, making the composition particularly suitable for small-scale package production.

[0092] [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).

[0093] [Curability] When at least a portion of component (F) contains a curing-reactive component (F2), 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-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 (H), curing may be triggered by irradiation with high-energy rays.

[0094] 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.

[0095] [Thermal Conductivity] The thermally conductive composition of the present invention can be stably and highly loaded with a thermally conductive filler and preferably has a thermal conductivity of 9.0 W / mK or higher, particularly preferably 9.1 W / mK or higher. The thermally conductive composition of the present invention can be designed to have a thermal conductivity of 9.0 to 15.0 W / mK, or optionally, a thermal conductivity of 9.1 to 14.0 W / mK, and also has excellent workability, such as extrudability from cartridges and dispensability. Furthermore, the composition may be either non-curable or curable. In the case of a curable composition, the use of component (J) / (K) (particularly the use of at least one of the phthalocyanine compound (component (K1)) and carbon black (component (K2)) suppresses hardness change even after heat aging, enabling the realization of a thermally conductive cured product with excellent flexibility and stress relaxation properties. Similarly, by using an organopolysiloxane that contains component (E1) as component (E) and in which, in the general formula (1), a is a number in the range of 40 to 90 and b is 3, it may be possible to improve not only extrusion workability and thermal conductivity, but also heat aging properties, particularly at high temperatures, to be favorably improved.

[0096] [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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] [Preparation of Composition and Creation of Cured Thermally Conductive Silicone Product (Evaluation Sample)] The components were mixed using the method described below to obtain the thermally conductive compositions of Examples 1 to 12 and Comparative Examples 1 to 6 (hereinafter sometimes referred to as "thermally conductive silicone compositions"). Furthermore, when the composition was curable, the thermally conductive silicone composition was filled into a mold measuring 6 mm in height, 50 mm in length, and 30 mm in width, cured at 80°C for 30 minutes, and then removed from the mold to obtain a cured thermally conductive silicone product. The hardness of the resulting cured thermally conductive silicone product was measured using the following method. [Hardness (Type E Hardness)] To measure hardness, two sheets of the cured thermally conductive silicone product obtained under the above conditions were stacked on top of each other, and the value after 3 seconds was measured using an ASKER TYPE E hardness tester manufactured by ASKER Corporation.

[0102] [Thermal conductivity] A Dyn TIM tester (manufactured by Siemens) was used to measure thermal conductivity. Thermal resistance was measured when the thermally conductive composition had a thickness of 800 μm, 600 μm, 400 μm, and 200 μm, and the thermal conductivity was calculated from the slope. [Extrusion amount] The thermally conductive composition was filled into a 30 cc EFD syringe (manufactured by Nordson) and extruded at an extrusion pressure of 80 psi, and the extrusion amount was measured as the extrusion weight per minute.

[0103] The composition of the present invention is formed from the following components. Note that the thermally conductive fillers used in the examples all contain 0% by volume of irregular aluminum nitride powder particles having an average particle size of less than 2.0 μm. Component (A): A-1: ​​irregular zinc oxide powder with an average particle size of 0.12 μm A-2: polyhedral α-type aluminum oxide powder with an average particle size of 0.5 μm A-3: polyhedral α-type aluminum oxide powder with an average particle size of 0.24 μm

[0104] Component (B): B-1: Polyhedral α-type aluminum oxide powder with an average particle size of 2 μm B-2: Irregular aluminum nitride powder with an average particle size of 19 μm and 0 volume % of particles of 2.5 μm or less B-3: Irregular aluminum nitride powder with an average particle size of 28 μm and 0 volume % of particles of 6 μm or less Non-B-1: Irregular aluminum nitride powder with an average particle size of 2 μm (45.3 volume % of particles less than 2 μm) Non-B-2: Irregular aluminum nitride powder with an average particle size of 1.2 μm

[0105] Component (C): C-1: Irregular aluminum nitride powder with an average particle size of 30 μm and 0 volume % of particles of 3 μm or less C-2: Irregular aluminum nitride powder with an average particle size of 100 μm and 0 volume % of particles of 26 μm or less C-3: Irregular aluminum nitride powder with an average particle size of 157 μm and 0 volume % of particles of 52 μm or less

[0106] Component (D): D-1: Spherical aluminum nitride powder with an average particle size of 80 μm

[0107] Component (X): X-1: Spherical magnesium oxide powder with an average particle size of 120 μm X-2: Spherical fused and solidified aluminum oxide powder with an average particle size of 90 μm

[0108] Component (E): E-1: Formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ３０ Si(OCH ３ ) ３ Organopolysiloxane E-2: represented by the formula: (C ２ H ５ )(CH ３ ) ２ SiO[(CH ３ ) ２ SiO ２７ Si(OCH ３ ) ３ E-3: Decyltrimethoxysilane E-4: Organopolysiloxane represented by the formula: (CH ３ ) ３ SiO[(CH ３ ) ２ SiO ６０ Si(OCH ３ )３ Organopolysiloxane represented by

[0109] Component (F): F-1: Dimethylpolysiloxane endblocked at both molecular chain terminals with trimethylsiloxy groups (viscosity 20 mPa·s) F-2: Dimethylpolysiloxane endblocked at both molecular chain terminals with dimethylvinylsiloxy groups (viscosity 60 mPa·s, Vi content 1.53% by mass) F-3: Dimethylpolysiloxane endblocked at both molecular chain terminals with dimethylvinylsiloxy groups (viscosity 28 mPa·s, Vi content 2.3% by mass)

[0110] Component (G): G-1: Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both molecular chain terminals with trimethylsiloxy groups, with an average of two per molecule and two on the side chains (viscosity 20 mPa·s, Si—H content 0.10% by mass); G-2: Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both molecular chain terminals with trimethylsiloxy groups, with an average of five per molecule and five on the side chains (viscosity 5 mPa·s, Si—H content 0.77% by mass); G-3: Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both molecular chain terminals with trimethylsiloxy groups, with an average of three per molecule and three on the side chains (viscosity 12 mPa·s, Si—H content 0.21% by mass); G-4: 1,1,1,3,5,5,5-heptamethyltrisiloxane (Si—H Content 0.45% by mass)

[0111] Component (H): H-1: A complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, with a platinum concentration of 0.6% by weight. Component (Y): Y-1: Phenylbutynol. Y-2: Methyltris-1,1-dimethyl-2-propynyloxysilane. Component (K): K-1: 29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32 copper.

[0112] Other ingredients: Component (J-1): calcium stearate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (K-2-1) carbon black-1: manufactured by Cancarb Co., Ltd., product number THERMAX FLOFORM N-990 (particle size 280 nm, specific surface area 9 m ２ / g) (K-2-2) Carbon Black-2: Denka Black (product number: Denka Co., Ltd., particle size 36 nm, specific surface area 58 m ２ / g) (K-2-3) Carbon black-3: Asahi Carbon Co., Ltd., product number SUNBLACK 235 (particle size 78 nm, specific surface area 21 m ２ / g)

[0113] Example 1 16.5 parts by mass of component (A-1), 29.5 parts by mass of component (B-1), 18.0 parts by mass of component (C-1), 1.50 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), and 2.73 parts by mass of component (F-1) were weighed into a 300 ml plastic container and mixed for 1 minute at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 10.8 parts by mass of component (D-1) and 20.77 parts by mass of component (X-1) were added and mixed for 1 minute at 2000 rpm. After scraping off the components from the wall of the plastic container with a spatula, the mixture was mixed for 1 minute at 2000 rpm. After cooling to room temperature, the mixture was vacuum degassed for 3 minutes to prepare a thermally conductive silicone composition.

[0114] Example 2 24.0 parts by mass of component (A-1), 28.6 parts by mass of component (B-1), 18.0 parts by mass of component (C-1), 1.50 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), and 2.60 parts by mass of component (F-1) were weighed into a 300 ml plastic container and mixed for 1 minute at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 10.0 parts by mass of component (D-1) and 15.1 parts by mass of component (X-1) were added and mixed for 1 minute at 2000 rpm. A thermally conductive silicone composition was then prepared in the same manner as in Example 1.

[0115] Example 3 16.8 parts by mass of component (A-1), 18.0 parts by mass of component (B-1), 18.0 parts by mass of component (C-1), 1.50 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), and 2.81 parts by mass of component (F-1) were weighed into a 300 ml plastic container and mixed for 1 minute at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 11.4 parts by mass of component (D-1) and 31.29 parts by mass of component (X-1) were added and mixed for 1 minute at 2000 rpm. A thermally conductive silicone composition was then prepared in the same manner as in Example 1.

[0116] Example 4 24.18 parts by mass of component (A-1), 23.0 parts by mass of component (B-1), 18.0 parts by mass of component (C-1), 1.50 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), and 2.62 parts by mass of component (F-1) were weighed into a 300 ml plastic container, and these were mixed for 1 minute at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 4.50 parts by mass of component (D-1) and 26.0 parts by mass of component (X-1) were added, and the mixture was mixed for 1 minute at 2000 rpm. A thermally conductive silicone composition was then prepared in the same manner as in Example 1.

[0117] Comparative Example 1: 17.45 parts by mass of component (A-1), 25.5 parts by mass of component (Non-B-1), 18.0 parts by mass of component (C-1), 1.59 parts by mass of component (E-1), 0.21 parts by mass of component (E-3), and 2.90 parts by mass of component (F-1) were weighed into a 300 ml plastic container, and mixed for 1 minute at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 12.6 parts by mass of component (D-1) and 21.8 parts by mass of component (X-1) were added, and mixed for 1 minute at 2000 rpm. A thermally conductive silicone composition was then prepared in the same manner as in Example 1.

[0118] Comparative Example 2 A thermally conductive silicone composition was prepared in the same manner as in Comparative Example 1, except that 25.5 parts by mass of component (Non-B-1) in Comparative Example 1 was replaced with 25.5 parts by mass of component (Non-B-2).

[0119] Table 1 shows the composition, thermal conductivity, and extrusion amount of the thermally conductive silicone compositions obtained for Examples 1 to 4 and Comparative Examples 1 and 2.

[0120]

[0121] Example 5: 14.5 parts by mass of component (A-2), 20.0 parts by mass of component (B-1), 18.0 parts by mass of component (C-1), 1.50 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), and 4.0 parts by mass of component (F-2) were weighed into a 300 ml plastic container and mixed for 1 minute at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 7.0 parts by mass of component (D-1) and 34.8 parts by mass of component (X-1) were added and mixed for 1 minute at 2000 rpm. After scraping the components off the wall of the plastic container with a spatula, the mixture was mixed for 1 minute at 2000 rpm. After cooling to room temperature, the mixture was vacuum degassed for 3 minutes to prepare a thermally conductive silicone composition.

[0122] Example 6 A thermally conductive silicone composition was prepared in the same manner as in Example 5, except that the 18.0 parts by mass of component (C-1) was replaced by 5.0 parts by mass, the 7.0 parts by mass of component (D-1) was replaced by 30.0 parts by mass, and the 34.8 parts by mass of component (X-1) was replaced by 24.8 parts by mass.

[0123] Comparative Example 3 A thermally conductive silicone composition was prepared in the same manner as in Example 5, except that the 18.0 parts by mass of component (C-1) was replaced by 3.0 parts by mass, the 7.0 parts by mass of component (D-1) was replaced by 32.0 parts by mass, and the 34.8 parts by mass of component (X-1) was replaced by 24.8 parts by mass.

[0124] Comparative Example 4 A thermally conductive silicone composition was prepared in the same manner as in Example 5, except that the 18.0 parts by mass of component (C-1) and 7.0 parts by mass of component (D-1) in Example 5 were replaced with 25.0 parts by mass of component (D-1).

[0125] Comparative Example 5 A thermally conductive silicone composition was prepared in the same manner as in Example 5, except that 18.0 parts by mass of component (C-1) was replaced with 18.0 parts by mass of component (B-3).

[0126] Table 2 shows the composition, thermal conductivity, and extrusion amount of the thermally conductive silicone compositions obtained for Examples 5 and 6 and Comparative Examples 3 and 5.

[0127]

[0128] Example 7: 14.3 parts by mass of component (A-2), 20.0 parts by mass of component (B-1), 1.20 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), 3.10 parts by mass of component (F-2), 0.850 parts by mass of component (G-1), and 0.15 parts by mass of component (K-1) were weighed into a 1000 ml plastic container, and mixed for 2 minutes at a rotation speed of 1500 rpm using a KURABO MAZERUSTAR. Next, 7.0 parts by mass of component (B-2), 18.0 parts by mass of component (C-1), 35.0 parts by mass of component (X-2), and 0.10 parts by mass of calcium stearate (J-1) were added and mixed for 2 minutes at a rotation speed of 1500 rpm. TOKUSHU KIKA KOGYO CO. The mixture was transferred to a T.K. HIVIS MIX (model number) manufactured by KOIKO ELECTRONICS CO., LTD., and heated and mixed at 160°C under reduced pressure for 60 minutes, after which it was cooled to room temperature to obtain a mixture. 0.020 parts by mass of component (G-2) and 0.0015 parts by mass of component (Y-1) were uniformly mixed with this mixture. 0.075 parts by mass of component (H-1) was then uniformly mixed to prepare a thermally conductive silicone composition.

[0129] Comparative Example 6 A thermally conductive silicone composition was prepared in the same manner as in Example 7, except that the 20.0 parts by mass of component (B-1) and 18.0 parts by mass of component (C-1) in Example 7 were replaced with 25.0 parts by mass of component (C-1).

[0130] Table 3 shows the composition, hardness, thermal conductivity, and extrusion amount of the thermally conductive silicone compositions obtained for Example 7 and Comparative Example 6.

[0131]

[0132] [Example 8] 16.5 parts by mass of component (A-1), 29.5 parts by mass of component (B-1), 1.50 parts by mass of component (E-1), 0.20 parts by mass of component (E-3), 1.68 parts by mass of component (F-3), 0.60 parts by mass of component (G-1), and 0.13 parts by mass of component (K-1) were weighed into a 1000 ml plastic container, and mixed for 2 minutes at a rotation speed of 1500 rpm using a KURABO MAZERUSTAR. Next, 18.0 parts by mass of component (B-3), 10.8 parts by mass of component (C-2), 20.7 parts by mass of component (X-1), and 0.10 parts by mass of calcium stearate (J-1) were added and mixed for 2 minutes at a rotation speed of 1500 rpm. TOKUSHU KIKA KOGYO CO. The mixture was transferred to a T.K. HIVIS MIX (model number) manufactured by KOIKO ELECTRONICS CO., LTD., and heated and mixed at 160°C under reduced pressure for 60 minutes, after which it was cooled to room temperature to obtain a mixture. 0.10 parts by mass of component (G-3), 0.149 parts by mass of component (G-4), and 0.0015 parts by mass of component (Y-1) were uniformly mixed with this mixture. 0.050 parts by mass of component (H-1) was then uniformly mixed to prepare a thermally conductive silicone composition.

[0133] Example 9 A thermally conductive silicone composition was prepared in the same manner as in Example 8, except that the 18.0 parts by mass of component (B-3) in Example 8 was replaced with 18.0 parts by mass of component (C-1) and the 10.8 parts by mass of component (C-2) was replaced with 10.8 parts by mass of component (D-1).

[0134] Example 10 16.5 parts by mass of component (A-1), 24.0 parts by mass of component (B-1), 5.5 parts by mass of component (B-2), 1.45 parts by mass of component (E-1), 0.050 parts by mass of component (E-2), 0.20 parts by mass of component (E-3), 1.78 parts by mass of component (F-3), 0.66 parts by mass of component (G-1), and 0.14 parts by mass of component (K-1) were weighed into a 1000 ml plastic container, and these were mixed for 2 minutes at 1500 rpm using a KURABO MAZERUSTAR. Next, 18.0 parts by mass of component (C-1), 20.8 parts by mass of component (D-1), 10.8 parts by mass of component (X-1), and 0.10 parts by mass of calcium stearate (J-1) were added and mixed for 2 minutes at 1500 rpm. The mixture was transferred to a T.K. HIVIS MIX (model number) manufactured by TOKUSHU KIKA KOGYO CO., LTD., and then heated and mixed at 160°C under reduced pressure for 60 minutes, followed by cooling to room temperature to obtain a mixture. 0.025 parts by mass of component (G-2) and 0.0015 parts by mass of component (Y-1) were uniformly mixed with this mixture. Then, 0.050 parts by mass of component (H-1) was uniformly mixed to prepare a thermally conductive silicone composition.

[0135] Example 11 16.5 parts by mass of component (A-1), 29.5 parts by mass of component (B-1), 1.45 parts by mass of component (E-1), 0.050 parts by mass of component (E-2), 0.20 parts by mass of component (E-3), 1.76 parts by mass of component (F-3), 0.65 parts by mass of component (G-1), and 0.14 parts by mass of component (K-1) were weighed into a 1000 ml plastic container and mixed for 2 minutes at 1500 rpm using a KURABO MAZERUSTAR. Next, 18.0 parts by mass of component (C-1), 10.8 parts by mass of component (D-1), 20.8 parts by mass of component (X-1), and 0.10 parts by mass of calcium stearate (J-1) were added and mixed for 2 minutes at 1500 rpm. The mixture was transferred to a T.K. HIVIS MIX (model number) manufactured by TOKUSHU KIKA KOGYO CO., LTD., and heated and mixed at 160°C under reduced pressure for 60 minutes, after which it was cooled to room temperature to obtain a mixture. 0.025 parts by mass of component (G-2) and 0.0015 parts by mass of component (J-1) were uniformly mixed with this mixture. Then, 0.060 parts by mass of component (H-1) was uniformly mixed to prepare a thermally conductive silicone composition.

[0136] Comparative Example 7 A thermally conductive silicone composition was prepared in the same manner as in Example 8, except that in Example 11, the 18.0 parts by mass of component (C-1) was replaced with 21.0 parts by mass.

[0137] Table 4 shows the composition, hardness, thermal conductivity, and extrusion amount of the thermally conductive silicone compositions obtained for Examples 8 to 11 and Comparative Example 7.

[0138]

[0139] Example 12 Into a 300 ml plastic container were weighed 12.5 parts by mass of component (A-3), 25.2 parts by mass of component (B-1), 22.8 parts by mass of component (B-2), 20.25 parts by mass of component (C-3), 15.4 parts by mass of component (D-1), 0.20 parts by mass of component (E-3), 1.00 parts by mass of component (E-4), 1.81 parts by mass of component (F-3), 0.55 parts by mass of component (G-1), 0.125 parts by mass of component (G-3), and 0.05 parts by mass of component (J-1): calcium stearate, and these were mixed for 2 minutes at 2000 rpm using a THINKY Planetary Vacuum Mixer. Next, 0.064 parts by mass of component (K-1) and 0.001 parts by mass of component (Y-2) were added and mixed for 1 minute at 2000 rpm. After the components were scraped off the wall of the plastic container with a spatula, the mixture was mixed for 1 minute at 2000 rpm and then cooled to room temperature to obtain a mixture. 0.05 parts by mass of component (H-1) was mixed uniformly with this mixture to prepare a thermally conductive silicone composition.

[0140] Example 13 14.28 parts by mass of component (A-1), 28.0 parts by mass of component (B-1), 0.20 parts by mass of component (E-3), 1.00 parts by mass of component (E-4), 2.30 parts by mass of component (F-3), 0.795 parts by mass of component (G-1), 0.125 parts by mass of component (G-3), and 0.10 parts by mass of component (J-1): calcium stearate were weighed into a T.K. HIVIS MIX (model number) manufactured by TOKUSHU KIKA KOGYO CO., LTD. and mixed for 10 minutes at a rotation speed of 12 rpm. Next, 19.0 parts by mass of component (B-2), 18.5 parts by mass of component (C-2), and 15.5 parts by mass of component (X-1) were weighed and mixed for 10 minutes at a rotation speed of 12 rpm. The mixture was then heated and mixed under reduced pressure at 160°C for 60 minutes, and then cooled to room temperature to obtain a mixture. 0.149 parts by mass of component (K-1) and 0.001 parts by mass of component (Y-2) were uniformly mixed with this mixture to prepare a thermally conductive silicone composition. 0.050 parts by mass of component (H-1) was then uniformly mixed to prepare a thermally conductive silicone composition.

[0141] Examples 13C1, C2, C3 Examples 13C1, 13C2, and 13C3 were prepared by blending the amounts shown in Table 5 of Carbon Black-1, Carbon Black-2, and Carbon Black-3 (K-2-1 to K-2-3) into the thermally conductive silicone composition of Example 13.

[0142] The compositions, hardness, thermal conductivity, extrusion amount, and heat resistance at 180°C of the thermally conductive silicone compositions of Examples 12 and 13, and 13C1 to 13C3 are shown in Table 5. In the table, values ​​common to Examples 13 and 13C1 to 13C3 are indicated by "←".

[0143] [Evaluation of heat resistance at 180°C] In order to confirm the hardening due to the addition of carbon black-1 to -3 as heat resistance imparting agents, the hardness and thermal conductivity of Examples 13C1 to 13C3 were evaluated as particularly good (⊚) when the change in hardness and thermal conductivity after heat aging at 180°C was further suppressed, with the no addition (Example 13) being used as the standard (good: ◯). The results are shown in Table 5.

[0144] [Summary] As shown in Table 1, Examples 1 to 4, which contained the components of the present invention within the specified ranges, exhibited thermal conductivities exceeding 11 W / m K and extrusion rates exceeding 50 g / min, demonstrating good workability. On the other hand, Comparative Example 1, which did not contain component (B), exhibited a thermal conductivity exceeding 9 W / m K, but the extrusion rate was 26 g / min, failing to exceed 30 g / min, which indicates sufficient extrusion workability. Furthermore, the composition of Comparative Example 2, which did not contain component (B), did not become pasty, and thermal conductivity measurement was also impossible.

[0145] As shown in Table 2, Examples 5 and 6, which contained the components of the present invention within the specified ranges, exhibited thermal conductivities exceeding 9 W / m K, and extrusion rates exceeded 60 g / min, demonstrating good workability. Comparative Example 3, which contained 30 volume percent or more of component (D), outside the specified range, had a thermal conductivity of 8.9 W / m K, not exceeding 9 W / m K. Similarly, Comparative Examples 4 and 5, which did not contain component (C), outside the specified range, had thermal conductivities of 7.6 W / m K and 8.7 W / m K, respectively.

[0146] As shown in Table 3, Example 7, which contained each component of the present invention within the specified range, had a thermal conductivity of 9.1 W / m K and an extrusion rate of 40 g / min, demonstrating good workability. Comparative Example 6, which contained 20% by volume or more of component (C), outside the specified range, had a thermal conductivity of 8.2 W / m K, not exceeding 9 W / m K.

[0147] As shown in Table 4, Examples 8 to 11, which contained the components of the present invention in amounts within the specified ranges, exhibited thermal conductivities exceeding 11 W / m K and extrusion rates exceeding 30 g / min, demonstrating good workability. All had Type E hardnesses of 60 or less after curing. Comparative Example 7, which contained 20% or more by volume of component (C), outside the specified range, had a Type E hardness of 62 after curing, exceeding 60, and therefore impaired stress relaxation properties and flexibility.

[0148] As shown in Table 5, Examples 12 and 13, which contained the components of the present invention within the specified ranges, exhibited thermal conductivities exceeding 11 W / m K. In particular, by using Component (E4) having a specific degree of siloxane polymerization in combination, the extrusion rate exceeded 30 g / min, demonstrating good workability. Furthermore, the Type E hardness after curing was also 60 or less. Furthermore, it was confirmed that the addition of carbon black to Example 13 (Examples 13C1 to 13C3) further improved the heat resistance at 180°C after curing compared to Example 13.

[0149] [Summary] The results of Examples 1 to 13 show that thermally conductive silicone compositions containing the components of the present invention within the specified ranges have a high thermal conductivity of 9 W / m·K or more, and an extrusion rate of over 30 g / min. Therefore, it is expected that they will have good workability and provide sufficient heat dissipation properties. Furthermore, when these compositions are designed to be cured reactively, the cured product has a Type E hardness of 60 or less, meaning that stress relaxation properties and flexibility are not impaired.

[0150] On the other hand, Comparative Examples 1 to 7 show that when the blending amounts of component (C) and component (D) are outside the scope of the claims of the present invention, the compositions according to these Comparative Examples have low thermal conductivities of 9 W / m K or less and extrusion rates of less than 30 g / min, which raises concerns that they may be difficult to work with or may not achieve sufficient heat dissipation properties. Furthermore, when the curable reactive compositions of the Comparative Examples were cured, the Type E hardness of the resulting cured product was 60 or more, which indicated that stress relaxation properties and flexibility were impaired.

Claims

1. (A) 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; (B) at least one thermally conductive filler selected from aluminum nitride powder and aluminum oxide powder, having an average particle size in the range of 2.0 to 29 μm, and having an irregular, rounded, and polyhedral shape; (C) aluminum nitride powder, having an average particle size of 30 μm or more, and having an irregular, rounded, and polyhedral shape; (D) aluminum nitride powder, having an average particle size of more than 50 μm, and being spherical; (E) one or more components selected from the following components (E1) to (E3); (E1) 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 an integer of 5 to 250, and b is an integer of 1 to 3.) and has a viscosity at 25°C of 10 to less than 10,000 mPa·s; (E2) an organopolysiloxane represented by 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 of 1 to 250; and d is an integer of 1 to 3. (E2) a siloxane compound having an alkenyl group and a hydrolyzable silyl group at a molecular chain terminal, the siloxane compound having a viscosity of 10 to 10,000 mPa·s at 25°C; and (E3) an alkoxysilane having an alkyl group having 6 or more carbon atoms in the molecule, or a hydrolysis condensate thereof. (F) one or more matrix polymers having a viscosity of 10 to 1,000,000 mPa·s at 25°C., wherein the content of the thermally conductive filler containing components (A) to (D) is in the range of 60 to 90 volume % based on the total solid content of the composition, the content of component (C) is in the range of 1.0 to 20.0 volume % based on the total solid content of the composition, and the content of component (D) is in the range of 0.0 to 30.0 volume % based on the total solid content of the composition.

2. The thermally conductive composition according to claim 1, wherein the thermally conductive filler containing components (A) to (D) is surface-treated with at least a portion of component (E).

3. The thermally conductive composition according to claim 1, wherein the thermally conductive filler containing components (A) to (D) is substantially free of aluminum nitride powder having an average particle size of less than 2.0 μm.

4. A thermally conductive composition according to claim 1, wherein the content of the aluminum nitride powder selected from component (B) and component (C) having an irregular shape, a rounded shape, and a polyhedral shape is 50 volume % or less based on the total solid content in the composition.

5. The thermally conductive composition according to claim 1, wherein the total content of the thermally conductive filler which is aluminum nitride powder is 60 volume % or less based on the total solid content in the composition.

6. The thermally conductive composition according to claim 1, wherein component (F) is (F0) one or more organopolysiloxanes having a viscosity at 25° C. in the range of 10 to 1,000,000 mPa·s.

7. The thermally conductive composition according to claim 1, wherein component (F) is one or more organopolysiloxanes selected from (F1) organopolysiloxanes having no curing reactive groups having carbon-carbon double bonds in the molecule and (F2) organopolysiloxanes having curing reactive groups having carbon-carbon double bonds in the molecule.

8. The thermally conductive composition according to claim 1, wherein component (F) at least contains (F2) an organopolysiloxane having a curing reactive group having a carbon-carbon double bond in the molecule, and also contains (G) an organohydrogenpolysiloxane in an amount such that there are 0.2 to 5 moles of silicon-bonded hydrogen atoms in component (G) per mole of the curing reactive group having a carbon-carbon double bond contained in component (F), and (H) a catalytic amount of a hydrosilylation reaction catalyst.

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

10. The thermally conductive composition according to claim 9, wherein said component (K) is a heat resistance imparting agent containing at least in part a component selected from (K1) a phthalocyanine compound and (K2) carbon black.

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

12. The thermally conductive composition according to claim 11, wherein said component (J) is (J1) 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.

13. The thermally conductive composition according to claim 1, wherein component (E) includes component (E1), and in general formula (1), a is a number in the range of 40 to 90, and b is 3.

14. A thermally conductive composition according to any one of claims 1 to 13, wherein the thermal conductivity of the composition or its cured reaction product is 9.0 W / mK or more.

15. A thermally conductive member comprising the thermally conductive composition according to any one of claims 1 to 13 or a cured reaction product thereof.

16. A heat dissipation structure comprising the thermally conductive member according to claim 15.

17. A heat dissipation structure comprising a heat dissipation component or a circuit board carrying said heat dissipation component, and a heat dissipation member provided via the thermally conductive composition or a cured product thereof according to any one of claims 1 to 13.

18. The heat dissipation structure according to claim 16 or 17, which is an electric / electronic device.

19. The heat dissipation structure according to claim 16 or 17, which is an electric / electronic component or a secondary battery.

20. A method for producing a thermally conductive composition according to any one of claims 1 to 13, comprising a step of mixing components (A) to (D), component (E) and component (F), heating and mixing the mixture, and then a step of mixing other components.

21. 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 13 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.

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