Thermally conductive silicone composition, cured product thereof, and production method therefor

Abstract

This thermally conductive silicone composition comprises: (A) an organopolysiloxane; (B) a spherical aluminum oxide powder in which the average sphericity is at least 0.8, the number of hydroxyl groups is at most 30 groups / nm2, the average particle diameter is at least 8 μm and less than 50 μm, and the proportion of coarse particles having a size of 96-150 μm is 0.1-30 mass% of the entire (B) component; (C) an irregularly shaped aluminum oxide powder having an average particle diameter of 0.1-5 μm; (D) an organopolysiloxane which is different from the (A) component, contains at least one silyl group per molecule, and has a viscosity of 0.01-30 Pa∙s at 25ºC; and (E) an ion trapping agent selected from among a cation exchange type and a dual-ion exchange type, and included in an amount of 0.01-10 parts by mass with respect to 100 parts by mass of the (A) component, wherein the blending volume ratio ((B):(C)) of the (B) component and the (C) component is 5:5 to 9.5:0.5, and said thermally conductive silicone composition has excellent preservability, insulation properties, and thermal conductivity.

Description

Thermally conductive silicone composition and its cured product, and method for producing it.

[0001] This invention relates to a thermally conductive silicone composition with excellent thermal conductivity, a cured product thereof, and a method for producing it. In particular, it relates to a highly thermally conductive silicone composition with excellent insulating properties and excellent thermal conductivity at high temperatures, which can be incorporated into electronic devices without damaging heat-generating electronic components such as power devices, transistors, thyristors, and CPUs (central processing units) when used as a heat dissipation material for electronic components.

[0002] For heat-generating electronic components such as power devices, transistors, thyristors, and CPUs, removing the heat generated during use is a critical issue. Conventionally, the common method of heat dissipation involves mounting the heat-generating electronic component to a heat sink fin or metal plate via an electrically insulating heat dissipation sheet, with the heat dissipation sheet typically being made of silicone resin with a thermally conductive filler dispersed within it.

[0003] In recent years, with the increasing integration of circuits within electronic components, the amount of heat generated has also increased. For example, thermal conductivity at high temperatures above 100°C, and especially at 150°C, is sometimes crucial, and there is a growing demand for materials with higher thermal conductivity than ever before. To improve the thermal conductivity of thermally conductive materials, the conventional method has been to incorporate fillers that exhibit high thermal conductivity, such as aluminum oxide powder and aluminum nitride powder, into the matrix resin.

[0004] Therefore, in order to improve thermal conductivity, Japanese Patent Publication No. 2013-056996 discloses a method for a highly thermally conductive resin composition in which spherical aluminum oxide powder has an average sphericity, hydroxyl group content, and average particle diameter specified to be 10 to 50 μm, and an average particle diameter specified to be 0.3 to 1 μm, with specified blending ratios and volume ratios of each type of aluminum oxide. However, with a maximum average particle diameter of 50 μm for the spherical aluminum oxide powder, there is no specification for thermal conductivity at high temperatures, resulting in insufficient thermal conductivity (Patent Document 1: Japanese Patent Publication No. 2013-056996).

[0005] Furthermore, although thermally conductive silicone compositions using alumina powder with an average particle size of 0.1 to 100 μm have been proposed, specific thermal conductivity and viscosity are not specified. In addition, although a thermally conductive silicone composition has been proposed that is defined by spherical alumina powder with an average particle size of 5 to 50 μm (excluding 5 μm) and spherical or irregularly shaped alumina powder with an average particle size of 0.1 to 5 μm, with the blending ratio and weight ratio of each aluminum oxide specified, there is no specification for the average sphericity of the spherical alumina with a larger average particle size or the amount of hydroxyl groups, which is insufficient for achieving high thermal conductivity at high temperatures (Patent Document 2: Japanese Patent No. 4646496).

[0006] Therefore, compositions using spherical aluminum oxide with specified average sphericity, hydroxyl group content, and average particle size have been proposed as the main filler. However, there remains a problem with storage stability, particularly in the cured form of the hydrosilylation reaction system (Patent Document 3: International Publication No. 2018 / 088416).

[0007] To improve the storage stability of the hydrosilylation reaction system, it was effective to specify a particular amount of Na ions generated from aluminum oxide, to perform surface treatment of the aluminum oxide with a specific organohydrogenpolysiloxane during the manufacturing process of the composition, and to use a cation exchange type and / or dual ion exchange type ion trapping agent. However, although there are examples of the average particle size of aluminum oxide, there is no description of the specifications for the average sphericity or the amount of hydroxyl groups, and it was difficult to achieve storage stability, especially in the cured form of the hydrosilylation reaction system, when aiming for even higher thermal conductivity (Patent Document 4: Japanese Patent Application Publication No. 2021-187874).

[0008] Japanese Patent Publication No. 2013-056996, Japanese Patent No. 4646496, International Publication No. 2018 / 088416, Japanese Patent Publication No. 2021-187874

[0009] The object of the present invention, made in view of the above circumstances, is to provide a thermally conductive silicone composition that is excellent in terms of storage properties, insulation properties, and thermal conductivity, without specifying a particular amount of Na ions generated from aluminum oxide, and without performing surface treatment of aluminum oxide with a specific organohydrogen polysiloxane in the composition manufacturing process. Another object is to provide a thermally conductive silicone composition suitable as a heat dissipation material for electronic components.

[0010] As a result of diligent research to achieve the above objective, the inventors of the present invention have found that the above problems can be solved by adopting the configuration described in item 1 below, and have thus come to the present invention.

[0011] Accordingly, the present invention provides the following: 1. (A) Organopolysiloxane (excluding component (D)), (B) Average sphericity of 0.8 or higher, with 30 hydroxyl groups / nm 2 The following are the characteristics of the spherical aluminum oxide powder, (B) having an average particle size of 8 μm or more and less than 50 μm, with the proportion of coarse particles of 96 to 150 μm in the laser diffraction particle size distribution being 0.1 to 30% by mass of the total component, (C) an amorphous aluminum oxide powder with an average particle size of 0.1 to 5 μm, and (D) the following general formula (1) -SiR 11 (3-α) (OR 12 ) α (1) (wherein, R 11 R is an unsubstituted or substituted monovalent hydrocarbon group, 12is independently a group selected from an alkyl group having 1 to 8 carbon atoms and an acyloxy group, and α is 1, 2 or 3. ), and contains at least 1 silyl group different from the component (A) in one molecule, and an organopolysiloxane having a viscosity at 25 ° C of 0.01 to 30 Pa·s, (E) a cation exchange type and a zwitterionic exchange type An ion trap agent selected from the above, and an ion trap agent supported with one or more elements selected from Zr, Bi, Sb, Mg and Al: 0.01 to 10 parts by mass with respect to 100 parts by mass of the component (A), A thermally conductive silicone composition comprising a volume ratio of the component (B) to the component (C) ((B):(C)) of 5:5 to 9.5:0.5. 2. The total amount of the component (B) and the component (C) is 65 to 80% by volume in the thermally conductive silicone composition, and the thermal conductivity of the thermally conductive silicone composition at 25 ° C is measured by the hot disk method according to ISO 22007-2. The thermally conductive silicone composition according to claim 1, which is 1.2 W / (m·K) or more and less than 5.5 W / (m·K), and has a viscosity at 25 ° C of 30 to 800 Pa·s when measured at a rotational speed of 10 rpm by a spiral viscometer. The highly thermally conductive silicone composition according to 3. 1 or 2, which is addition reaction curable, organic peroxide curable or condensation reaction curable. 4. The highly thermally conductive silicone composition according to 1 or 2 is addition reaction curable, and a cured product cured at 15 to 200 ° C by a hydrosilylation reaction. 5. A method for producing a thermally conductive silicone composition according to any one of 1 to 3, which comprises a step of mixing so that the volume ratio of the component (B) to the component (C) ((B):(C)) is 5:5 to 9.5:0.5.

[0012] According to the present invention, even without defining a specific amount of Na ions generated from aluminum oxide, and further without performing surface treatment of aluminum oxide with a specific organohydrogenpolysiloxane in the production process of the composition, it has excellent storage stability, insulation and thermal conductivity, and a thermally conductive silicone composition suitable as a heat dissipation member for electronic components can be provided.

[0013] Hereinafter, the thermally conductive silicone composition of the present invention will be described in detail, but the present invention is not limited thereto.

[0014] The present invention will be described in detail below. The present invention will be described in detail below. Note that "thermal conductive silicone composition" may be abbreviated as "composition". [Component (A)] Component (A), the organopolysiloxane, is the main component of the silicone composition of the present invention and can be used alone or in combination of two or more. The molecular structure of the organopolysiloxane is not limited, but linear or partially branched linear is preferred. Examples of such organopolysiloxanes include single polymers having these molecular structures, copolymers consisting of these molecular structures, or mixtures of these polymers. Groups bonded to the silicon atom in organopolysiloxane include, for example, linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups; isopropyl, tertiary-butyl, isobutyl, 2-methylundecyl, and 1 Examples include branched alkyl groups such as hexylheptyl groups; cyclic alkyl groups such as cyclopentyl groups, cyclohexyl groups, and cyclododecyl groups; alkenyl groups such as vinyl groups, allyl groups, butenyl groups, pentenyl groups, and hexenyl groups; aryl groups such as phenyl groups, tolyl groups, and xylyl groups; aralkyl groups such as benzyl groups, phenethyl groups, and 2-(2,4,6-trimethylphenyl)propyl groups; and halogenated alkyl groups such as 3,3,3-trifluoropropyl groups and 3-chloropropyl groups. Details of component (A) will be described later.

[0015] The viscosity of the component (A) at 25°C is not limited, but is preferably 20 to 100,000 mPa·s, more preferably 50 to 70,000 mPa·s, still more preferably 70 to 50,000 mPa·s, and particularly preferably 100 to 10,000 mPa·s. By setting the viscosity to be not less than the above lower limit, the physical properties of the resulting cured product are further improved. On the other hand, by setting it to be not more than the upper limit of the above range, the handling workability of the silicone composition is further improved. In the present invention, the viscosity of each component may be expressed in terms of rotational viscosity and kinematic viscosity. The rotational viscosity is a value measured by a BM-type viscometer, a BH-type viscometer or a BS-type viscometer (for example, manufactured by Tokyo Keiki Co., Ltd.) at 25°C. The rotor, rotation speed and rotation time are appropriately selected based on a conventional method according to the viscosity. The kinematic viscosity is a value measured using an Ostwald-type viscometer at 25°C. Note that the viscosity of the entire composition is defined separately.

[0016] The amount of the component (A) is preferably 1 to 15% by volume, more preferably 2 to 14% by volume in the composition.

[0017] [Component (B)] The component (B) is spherical aluminum oxide powder having an average sphericity of 0.8 or more, 30 or less hydroxyl groups per nm 2 or less, an average particle diameter of 8 μm or more and less than 50 μm, and the proportion of coarse particles of 96 to 150 μm in the laser diffraction particle size distribution is 0.1 to 30% by mass of the entire component (B). If the above range is satisfied, two or more types having different average particle diameters may be used in combination.

[0018] The crystal structure of the aluminum oxide powder may be either a single crystal or a polycrystal, but the crystal phase is preferably the α-phase from the viewpoint of high thermal conductivity, and the specific gravity is preferably 3.7 (g / cm 3 ) or more. By setting the specific gravity to be 3.7 or more, the proportion of voids and low crystal phases present inside the particles can be reduced, and the thermal conductivity can be further increased. The particle size adjustment of the aluminum oxide powder can be performed by a classification and mixing operation.

[0019] The average sphericity is 0.8 or higher, preferably 0.80 or higher, more preferably 0.85 or higher, even more preferably 0.9 or higher, and particularly preferably 0.90 or higher. If the average sphericity is less than 0.8, fluidity may decrease. If the average sphericity is less than 0.8, contact between particles becomes significant, the surface irregularities of the sheet become larger, the interfacial thermal resistance increases, and the thermal conductivity tends to worsen. There is no particular upper limit, but the closer it is to a sphere (average sphericity 1), the better.

[0020] In this invention, the average sphericity can be measured by importing particle images captured with a scanning electron microscope into an image analysis device, such as the JEOL Corporation product name "JSM-7500F," and measuring as follows: The projected area (X) and perimeter (Z) of the particle are measured from the photograph. If the area of ​​a perfect circle corresponding to the perimeter (Z) is (Y), then the sphericity of the particle can be expressed as X / Y. Assuming a perfect circle with the same perimeter (Z) as the sample particle, Z = 2πr and Y = πr 2 Therefore, Y = π × (Z / 2π) 2 Therefore, the sphericity of each particle is given by: Sphericity = X / Y = X × 4π / Z 2 It can be calculated as follows. The sphericity of 100 arbitrary particles obtained in this way is determined, and the average value is taken as the average sphericity.

[0021] Hydroxyl groups: 30 per nm 2 The following applies: 28 particles / nm 2 The following is preferable: 25 particles / nm 2 The following is more preferable: 30 hydroxyl groups / nm 2 If this value is exceeded, the fillability of the resin may deteriorate, potentially leading to poor thermal conductivity. There is no lower limit for the surface hydroxyl groups, but for example, 5 groups / nm 2 It can be done this way.

[0022] The number of hydroxyl groups in this invention, i.e., the surface hydroxyl group concentration, can be measured by Karl Fischer coulometric titration, for example, using the "Trace Moisture Analyzer CA-100" manufactured by Mitsubishi Chemical Corporation. Specifically, 0.3 to 1.0 g of the sample is placed in a moisture vaporizer, and the sample is heated using an electric heater while supplying dehydrated argon gas as a carrier gas. In the Karl Fischer coulometric titration method, the amount of moisture generated between 200°C and 900°C is defined as the amount of surface hydroxyl groups. The concentration of surface hydroxyl groups is calculated from the measured amount of moisture and specific surface area.

[0023] The average particle diameter is 8 μm or more and less than 50 μm, preferably 10 to 45 μm, and more preferably 13 to 42 μm. If the average particle diameter is less than 8 μm, there will be less contact between particles, which may lead to an increase in interparticle contact thermal resistance and a decrease in thermal conductivity. If the average particle diameter is 50 μm or more, the surface irregularities of the sheet will increase, which may increase the interfacial thermal resistance and a decrease in thermal conductivity.

[0024] Component (B) has a laser diffraction particle size distribution where the proportion of coarse particles measuring 96 to 150 μm is 0.1 to 30 mass%, more preferably 0.1 to 15 mass%. This range allows for both the desired thickness and high thermal conductivity. If the proportion of coarse particles measuring 96 to 150 μm is less than 0.1 mass%, the desired thickness of 100 to 150 μm cannot be achieved, and high thermal conductivity cannot be attained. If it is 30 mass% or more, the desired thickness of 100 to 150 μm can be achieved, but the packing performance of component (B) tends to deteriorate.

[0025] In this invention, the average particle size can be measured using a laser diffraction particle size distribution analyzer, for example, the Shimadzu Corporation's "Laser Diffraction Particle Size Distribution Analyzer SALD-2300". For the evaluation sample, 5 g of the thermal conductive powder to be measured is added to 50 cc of pure water in a glass beaker, stirred with a spatula, and then dispersed in an ultrasonic cleaner for 10 minutes. The dispersed thermal conductive powder solution is added drop by drop to the sampler section of the analyzer using a dropper, and the sample is allowed to stabilize until the absorbance can be measured. Measurement is then performed once the absorbance has stabilized. The laser diffraction particle size distribution analyzer calculates the particle size distribution from the data of the light intensity distribution of the diffracted / scattered light from the particles detected by the sensor. The average particle size is obtained by multiplying the measured particle size by the relative particle amount (difference %) and dividing by the total relative particle amount (100%). Note that the average particle size is the average diameter of the particles. Furthermore, the proportion of coarse particles 96 μm or larger can also be easily determined from the overall particle size distribution (by volume).

[0026] [Component (C)] Component (C) is an amorphous aluminum oxide powder with an average particle size of 0.1 to 5 μm, and may be used alone or in combination of two or more types with different average particle sizes. The average particle size is 0.1 to 5 μm, with 0.5 to 2 μm being preferred. If the average particle size is less than 0.1 μm, contact between particles decreases, and the thermal conductivity tends to worsen due to an increase in interparticle contact thermal resistance. If it is greater than 5 μm, the surface irregularities of the sheet become larger, increasing the interfacial thermal resistance and tending to worsen the thermal conductivity. Furthermore, there is a risk that the capture rate of Na+ ions generated by component (C) by component (E), which will be described later, will be poor.

[0027] Furthermore, "irregular shape" refers to any shape that has not undergone intentional spheroidization treatment such as melting or granulation. In addition, while component (C) also exists in rounded and spherical shapes, spherical refers to those that are commercially available in a spherical shape after being treated with melting or granulation, while rounded refers to particles with few corners and a smooth, rounded state, and does not include spherical particles. These can be distinguished from irregular shapes.

[0028] The volume ratio of the above-mentioned components (B):(C) is 5:5 to 9.5:0.5, preferably 5.0:5.0 to 9.5:0.5, and more preferably 6:4 to 9:1. If the proportion of component (B) is less than 5 by volume (the sum of components (B) and (C) is 10, and so on), the filler's packing ability will be poor. On the other hand, if it is greater than 9.5, it becomes difficult to pack the filler densely, and the thermal conductivity tends to decrease.

[0029] The total amount of component (B) and component (C) is preferably 65 to 80% by volume, and more preferably 70 to 80% by volume, in the thermally conductive silicone composition. By making the total amount of component (B) and component (C) 60% by volume or more, the thermal conductivity of the composition is further improved, while if it is 80% by volume or less, filling with a thermally conductive filler is easy.

[0030] [Component (D)] Component (D) of the present invention is the following general formula (1) -SiR 11 (3-α) (OR 12 ) α (1) (wherein, R 11 R is independently an unsubstituted or substituted monovalent hydrocarbon group. 12 (A) is a group selected from alkyl groups and acyloxy groups having 1 to 8 carbon atoms, and α is 1, 2, or 3. (A) is an organopolysiloxane that contains at least one silyl group different from component (A) in one molecule and has a viscosity of 0.01 to 30 Pa·s at 25°C, and can be used alone or in combination of two or more. Component (D) makes it possible to obtain a composition with good handling and workability even when components (B) and (C) are contained in large quantities.

[0031] An organopolysiloxane having at least one silyl group represented by the above general formula (1) in one molecule is the following general formula (2): (In the formula, R 11 R is independently an unsubstituted or substituted monovalent hydrocarbon group. 12 Examples of organopolysiloxanes are those represented by α, where α is independently selected from alkoxy groups and acyloxy groups having 1 to 8 carbon atoms, α is 1, 2, or 3, and β is an integer from 2 to 100.

[0032] In the above (1) and (2), R 11 Each is independently an unsubstituted or substituted monovalent hydrocarbon group, preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. Specifically, examples include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups. Examples of linear alkyl groups include methyl, ethyl, propyl, hexyl, octyl, and decyl groups. Examples of branched alkyl groups include isopropyl, isobutyl, tert-butyl, and 2-ethylhexyl groups. Examples of cyclic alkyl groups include cyclopentyl and cyclohexyl groups. Examples of alkenyl groups include vinyl and allyl groups. Examples of aryl groups include phenyl and tolyl groups. Examples of aralkyl groups include 2-phenylethyl and 2-methyl-2-phenylethyl groups. Examples of halogenated alkyl groups include 3,3,3-trifluoropropyl group, 2-(nonafluorobutyl)ethyl group, and 2-(heptadecafluorooctyl)ethyl group. 11 A methyl group or a phenyl group is preferred.

[0033] R 12 R is independently selected from alkyl groups and acyloxy groups having 1 to 8 carbon atoms. 12 Examples of the groups include methoxy, ethoxy, and isopropoxy groups, with methoxy and ethoxy groups being preferred, and methoxy groups being more preferred. α is 1, 2, or 3, with 3 being more preferred.

[0034] (D) Suitable specific examples of organopolysiloxanes of component D are listed below. (In the formula, Me represents a methyl group.)

[0035] Component (D) has a viscosity of 0.01 to 30 Pa·s at 25°C, preferably 0.1 to 10 Pa·s. A viscosity of 0.01 Pa·s or higher suppresses oil bleeding and dripping from the resulting silicone composition. A viscosity of 30 Pa·s or lower improves the fluidity of the resulting silicone composition, making application easier. The viscosity of component (D) is measured at 25°C using a BM-type viscometer, BH-type viscometer, or BS-type viscometer (for example, manufactured by Tokyo Keiki Co., Ltd.). The rotor, rotation speed, and rotation time should be appropriately selected according to the viscosity based on conventional methods.

[0036] (D) As a surface treatment method for spherical alumina powder, a spray method using a fluid nozzle, a stirring method with shear force, a dry method using a ball mill or mixer, or a wet method using an aqueous or organic solvent system can be employed. When using the stirring method, it is important to do so to the extent that the spherical aluminum oxide powder is not destroyed. In the dry method, the system temperature or the drying temperature after treatment is appropriately determined according to the type of surface treatment agent, within a range in which the surface treatment agent does not volatilize or decompose, but 80 to 180°C is preferred.

[0037] The amount of component (D) is preferably 10 to 900 parts by mass, and more preferably 20 to 700 parts by mass, per 100 parts by mass of component (A). By using 5 parts by mass or more of component (D), a softer composition can be obtained after heating. By using 900 parts by mass or less, the composition becomes easier to harden. Furthermore, the amount of component (D) is preferably 1 to 25 volume%, and more preferably 2 to 20 volume%, of the total composition.

[0038] [Component (E)] Component (E) is an ion trapping agent selected from cation exchange type and dual ion exchange type, and may be any of cation exchange type, dual ion exchange type, cation exchange type, or dual ion exchange type. It is an ion trapping agent on which one or more elements selected from Zr, Bi, Sb, Mg, and Al are supported, and can be used alone or in combination of two or more. Na contained in components (B) and (C) of the composition of the present invention +When the composition described later is cured by a hydrosilylation reaction due to ions, component (F) is a curing agent that has an average of two or more silicon-bonded hydrogen atoms per molecule, and is a component that can suppress the deterioration of the platinum-based catalyst over time. Therefore, anion exchange type trapping agents are not suitable in the present invention.

[0039] Component (E) is supported with at least one element selected from Zr, Bi, Sb, Mg, and Al, preferably selected from Zr, Bi, Mg, and Al, and more preferably selected from Zr, Mg, and Al.

[0040] Component (E) is not particularly limited in other respects, but its support is preferably one or more selected from, for example, hydrotalcites and inorganic ion exchangers such as polyvalent metal acid salts. Among these, it is more preferable that it is supported by hydrotalcites from the viewpoint of improving the storage properties of the composition of the present invention.

[0041] The amount of elemental support for component (E) is preferably 0.1 to 10 meq / g, and more preferably 1 to 8 meq / g, as the total exchange amount of each ion. Within this range, the storage properties of the composition of the present invention can be more effectively improved. The total exchange amount of ions refers to the amount of ion exchange in 0.1N hydrochloric acid or 0.1N aqueous sodium hydroxide solution.

[0042] (E) Component can be a commercially available product such as IXE-100, IXE-600, IXEPLAS-A1, or IXEPLAS-A2 (manufactured by Toagosei Co., Ltd.).

[0043] The amount of component (E) is 0.01 to 10 parts by mass per 100 parts by mass of component (A), preferably 0.1 to 9 parts by mass, more preferably 0.5 to 8 parts by mass, even more preferably 0.6 to 5 parts by mass, and particularly preferably 0.7 to 3 parts by mass. If the amount of component (E) is less than 0.01 parts by mass, the deterioration of component (G) over time, which will be described later, may not be suppressed, and if the amount of component (E) exceeds 10 parts by mass, there is a risk that appropriate curability cannot be obtained.

[0044] [Curable Composition] This composition can also be further modified by adding a curing agent to make it curable. In this case, the curing mechanism of this composition is not limited and includes, for example, an addition reaction (hydrosilylation reaction), a condensation reaction, and a radical reaction with an organic peroxide. An addition reaction (hydrosilylation reaction) is preferred because it cures quickly and does not generate by-products.

[0045] [Addition reaction curable silicone composition] In the case of an addition reaction curable silicone composition, component (A) is (A-I) the following formula (I-1) (In the formula, R 1 R is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, 2 (I-2) is an alkenyl group, and a1, a2, b1, b2, b3, c1, c2, and d are a1≧0, a2≧0, b1≧0, b2≧0, b3≧0, c1≧0, c2≧0, and d≧0, and a2+b2+b3+c2>0, respectively. ) This is an organopolysiloxane having an alkenyl group bonded to a silicon atom, represented by the following formula (I-2) (In the formula, R 3 (I-3) These are independently unsubstituted or substituted monovalent hydrocarbon groups that do not have aliphatic unsaturated bonds, and e1, e2, f1, f2, f3, g1, g2 and h are e1≧0, e2≧0, f1≧0, f2≧0, f3≧0, g1≧0, g2≧0 and h≧0, and e2+f2+f3+g2>0.) Examples include organohydrogenpolysiloxanes having hydrogen atoms bonded to silicon atoms, and (I-3) platinum group metal-based hardening catalysts.

[0046] [Organopolysiloxane having an alkenyl group bonded to a silicon atom (A-I)] The (A-I) component is represented by the following formula (I-1) (In the formula, R 1 R is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, 2) is an organopolysiloxane having alkenyl groups bonded to silicon atoms, represented by ( ), where a1, a2, b1, b2, b3, c1, c2, and d are a1≧0, a2≧0, b1≧0, b2≧0, b3≧0, c1≧0, c2≧0, and d≧0, and a2+b2+b3+c2>0, respectively. It can be used alone or in combination of two or more types. In particular, it is an organopolysiloxane having an average of 0.1 or more silicon-bonded alkenyl groups per molecule. More preferably, the average number of silicon-bonded alkenyl groups is 0.5 or more, and even more preferably 0.8 or more. This is because the resulting composition hardens more sufficiently when the average number of silicon-bonded alkenyl groups in one molecule is above the above range.

[0047] In the above formula (I-1), R 1 These are independently unsubstituted or substituted monovalent hydrocarbon groups that do not have aliphatic unsaturated bonds, and specifically include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, aryl groups, aralkyl groups, halogenated alkyl groups, etc. Among these, groups bonded to silicon atoms other than alkenyl groups in organopolysiloxanes include linear alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, isopropyl group, tert-butyl group, isobutyl group, 2-methylundecyl group, Examples include branched alkyl groups such as 1-hexylheptyl group, cyclic alkyl groups such as cyclopentyl group, cyclohexyl group, and cyclododecyl group, aryl groups such as phenyl group, tolyl group, and xylyl group, aralkyl groups such as benzyl group, phenethyl group, and 2-(2,4,6-trimethylphenyl)propyl group, and halogenated alkyl groups such as 3,3,3-trifluoropropyl group and 3-chloropropyl group. Alkyl and aryl groups are preferred, and methyl and phenyl groups are more preferred.

[0048] a1, a2, b1, b2, b3, c1, c2, and d are a1≧0, a2≧0, b1≧0, b2≧0, b3≧0, c1≧0, c2≧0, and d≧0, respectively, and preferably 0≦a1≦2, 1≦a2≦2, 50≦b1≦1,200, 0≦b2≦20, 0≦b3≦10, 0≦c1≦5, 0≦c2≦5, and 0≦d≦5, and more preferably 55≦b1≦1,000, 0≦b2≦10, and 0≦b3≦5. a2+b2+b3+c2>0 and preferably a2+b2+b3+c2>1.

[0049] The molecular structure of organopolysiloxanes is not limited and can include, for example, linear, branched, partially branched linear, cyclic, and dendritic (dendrimer) structures. Examples of such organopolysiloxanes include monopolymers having these molecular structures, copolymers consisting of these molecular structures, or mixtures thereof.

[0050] Examples of organopolysiloxanes include dimethylpolysiloxane with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane with methylphenylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylphenylsiloxane copolymer with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer with trimethylsiloxy groups sealed at both ends of the molecular chain, methyl(3,3,3-trifluoropropyl)polysiloxane with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer with silanol groups sealed at both ends of the molecular chain, and dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer with silanol groups sealed at both ends of the molecular chain, formula: (CH3)3SiO 1 / 2 Siloxane units and formula represented by: (CH3)2(CH2=CH)SiO 1 / 2 Siloxane units and formula represented by: CH3SiO 3 / 2 Siloxane units and formula represented by: (CH3)2SiO 2 / 2Examples include organosiloxane copolymers consisting of siloxane units represented by , dimethylpolysiloxane with silanol groups sealed at both ends of the molecular chain, dimethylsiloxane / methylphenylsiloxane copolymer with silanol groups sealed at both ends of the molecular chain, dimethylpolysiloxane with trimethoxysiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylphenylsiloxane copolymer with trimethoxysilyl groups sealed at both ends of the molecular chain, dimethylpolysiloxane with methyldimethoxysiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane with triethoxysiloxy groups sealed at both ends of the molecular chain, dimethylpolysiloxane with trimethoxysilylethyl groups sealed at both ends of the molecular chain, and mixtures of two or more of these.

[0051] [(I-2): Organohydrogenpolysiloxane having hydrogen atoms bonded to silicon atoms (hereinafter sometimes referred to as component (F))] Component (I-2) is given by the following formula (I-2) (In the formula, R 3 The organohydrogenpolysiloxane is an organohydrogenpolysiloxane having hydrogen atoms bonded to silicon atoms, which can be used alone or in combination of two or more types, and it is preferable that each molecule has an average of two or more hydrogen atoms bonded to silicon atoms. The viscosity of the organohydrogenpolysiloxane at 25°C is not limited, but is preferably 1 to 100,000 mPa·s, and more preferably 1 to 5,000 mPa·s. Note that viscosity may also be described separately as kinematic viscosity.

[0052] R 3 R is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, and R in formula (I-1) above 1Similar and preferred examples are given. The organohydrogenpolysiloxane may be linear or branched. For example, dimethylpolysiloxane with dimethylhydrogensiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylhydrogensiloxane copolymer with trimethylsiloxy groups sealed at both ends of the molecular chain, dimethylsiloxane / methylhydrogensiloxane copolymer with dimethylhydrogensiloxy groups sealed at both ends of the molecular chain, formula: (CH3)3SiO 1 / 2 Siloxane units and formula represented by: (CH3)2HSiO 1 / 2 Siloxane units and formula represented by: SiO 4 / 2 Examples include organosiloxane copolymers consisting of siloxane units represented by , and mixtures of two or more thereof.

[0053] e1, e2, f1, f2, f3, g1, g2, and h are such that e1≧0, e2≧0, f1≧0, f2≧0, f3≧0, g1≧0, g2≧0, and h≧0, respectively, and it is preferable that 0≦e1≦2, 1≦e2≦2, 0≦f1≦600, 1≦f2≦110, 0≦f3≦5, 0≦g1≦3, 0≦g2≦3, and 0≦h≦3. It is more preferable that 1≦f1≦500, 2≦f2≦100, and 0≦f3≦3. It is preferable that e2+f2+f3+g2>0 and e2+f2+f3+g2>2.

[0054] The amount of organohydrogenpolysiloxane used in this composition is the amount necessary for curing. Specifically, for every mole of silicon-bonded alkenyl groups in component (A-I), it is preferably 0.1 to 10 moles, more preferably 0.1 to 5 moles, and even more preferably 0.1 to 3.0 moles of silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane. Setting the amount above the lower limit provides sufficient curability, while setting it below the upper limit results in a very hard cured product, preventing the formation of numerous cracks on the surface.

[0055] [(I-3): Platinum group metal-based curing catalyst (hereinafter sometimes referred to as component (G))] Platinum group metal-based curing catalysts are catalysts for promoting the curing of compositions, and examples include chloroplatinic acid, alcoholic solutions of chloroplatinic acid, platinum olefin complexes, platinum alkenylsiloxane complexes, and platinum carbonyl complexes.

[0056] In this composition, the amount of platinum group metal curing catalyst to be blended is the amount necessary for curing the composition. Specifically, it is preferably 0.01 to 1,000 ppm (by mass) in terms of platinum metal relative to component (A), and more preferably 0.1 to 500 ppm. By setting the amount above the lower limit, sufficient curability can be obtained, and even if an amount exceeding the upper limit of the above range is blended, the curing speed of the resulting silicone composition does not significantly improve.

[0057] [Curing reaction inhibitor (hereinafter sometimes referred to as component (H))] When this composition hardens by an addition reaction (hydrosilylation reaction), it is preferable to include a curing reaction inhibitor to adjust the hardening rate of the composition and improve handling. Preferably, the curing reaction inhibitor contains acetylene compounds such as 2-methyl-3-butyne-2-ol, 2-phenyl-3-butyne-2-ol, and 1-ethynyl-1-cyclohexanol; en-yne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; and other curing reaction inhibitors such as hydrazine compounds, phosphine compounds, and mercaptan compounds.

[0058] The amount of curing reaction inhibitor to be included is not limited, but it is preferably 0.0001 to 1.0% by mass relative to the total composition. Setting the amount above the lower limit of the above range further improves the workability of the resulting composition. On the other hand, setting the amount below the upper limit of the above range prevents the curing rate of the resulting composition from becoming significantly slower.

[0059] [Organic Peroxide Curable Silicone Composition] In the case of an organic peroxide curable silicone composition, component (A) is (A-II) an organopolysiloxane having an alkenyl group bonded to a silicon atom, represented by the above formula (I-1), and further includes (II-2) an organic peroxide.

[0060] (A-II) The preferred range of the organopolysiloxane having an alkenyl group bonded to a silicon atom, represented by formula (I-1) above, is the same as described above.

[0061] (II-2) Organic Peroxides Examples of organic peroxides include benzoyl peroxide, dicumyl peroxide, 2,5-dimethylbis(2,5-t-butylperoxy)hexane, di-t-butyl peroxide, and t-butyl perbenzoate. The amount of organic peroxide to be added is the amount necessary for the curing of the composition, and specifically, 0.1 to 5 parts by mass per 100 parts by weight of the organopolysiloxane of component (A) above is preferred. This is because the composition obtained will cure more sufficiently if the amount of this component is above the lower limit of the above range. On the other hand, adding an amount exceeding the upper limit of the above range will not significantly improve the curing speed of the resulting silicone composition, and may even cause voids.

[0062] [Condensation reaction curable silicone composition] In the case of a condensation reaction curable silicone composition, component (A) is (A-III) the following general formula (III-1) (In the formula, R 4 R is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, and i is an integer of 1 or more. ) It is an organopolysiloxane represented by the following general formula (III-2) R 5 j -Six (4-j) (III-2) (wherein, R 5(III-3) A condensation reaction curing catalyst is included, which is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, X is a hydrolyzable group, and j is 0 or 1.

[0063] (A-III) is given by the following general formula (III-1) (In the formula, R 4 ) is an organopolysiloxane in which both ends are sealed with hydroxyl groups, and it can be used alone or in combination of two or more.

[0064] R 4 R is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, for example, the above R 1 Examples include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, and aralkyl groups. Among these, unsubstituted, halogen-substituted, or cyano-substituted alkyl groups with 1 to 5 carbon atoms or aryl groups with 6 to 8 carbon atoms are preferred.

[0065] The molecular structure of such organopolysiloxanes is not limited, and examples of structures similar to those described above are given, with linear and partially branched linear structures being preferred.

[0066] The component (III-2) is given by the following general formula (III-2) R 5 j -Six (4-j) (III-2) (wherein, R 5 X is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, X is a hydrolyzable group, and j is 0 or 1.) One or more selected from silane compounds represented by , their (partial) hydrolysates and (partial) hydrolyzate condensates, which can be used alone or in combination of two or more.

[0067] R 5 R is independently an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond, for example, the above R 1Similar groups can be cited. Examples include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, etc., as described above. Among these, unsubstituted, halogen-substituted, or cyano-substituted alkyl groups and phenyl groups having 1 to 3 carbon atoms are preferred. Examples of hydrolyzable groups of X include alkoxy groups such as methoxy, ethoxy, and propoxy groups; alkenoxy groups such as vinyloxy, propenoxy, isopropenoxy, and 1-ethyl-2-methylvinyloxy groups; alkoxyalkoxy groups such as methoxyethoxy, ethoxyethoxy, and methoxypropoxy groups; acyloxy groups such as acetoxy and octanoyloxy groups; ketoxime groups such as dimethylketoxime and methylethylketoxime groups; amino groups such as dimethylamino, diethylamino, and butylamino groups; aminooxy groups such as dimethylaminooxy and diethylaminooxy groups; and amide groups. (III-2) Examples of components include methyltriethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and ethyl orthosilicate.

[0068] (III-2) The amount of component (III-2) when incorporated is the amount necessary for the curing of the composition, and specifically, 0.01 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of component (A). By setting the amount of silane or its partial hydrolysate above the lower limit of the above range, the storage stability of the resulting composition becomes more stable and the adhesiveness is further improved. By setting it below the upper limit of the above range, it is possible to suppress the curing of the resulting composition from becoming significantly slower.

[0069] (III-3) Condensation reaction curing catalyst The condensation reaction curing catalyst is an optional component and is not essential when using a silane having hydrolyzable groups such as an aminooxy group, amino group, or ketoxime group as a curing agent. Examples of such condensation reaction catalysts include organotitanium esters such as tetrabutyl titanate and tetraisopropyl titanate; organotitanium chelate compounds such as diisopropoxybis(acetylacetate) titanium and diisopropoxybis(ethylacetate) titanium; organoaluminum compounds such as aluminum tris(acetylacetonate) and aluminum tris(ethylacetate); organoaluminum compounds such as zirconium tetra(acetylacetonate) and zirconium tetrabutyrate; dibutyltin dioctoate, dibutyl Examples include organotin compounds such as tin dilaurate and butyltin-2-ethylhexoate; metal salts of organic carboxylic acids such as tin naphthenate, tin oleate, tin butyrate, cobalt naphthenate, and zinc stearate; amine compounds such as hexylamine and dodecylamine phosphate, and their salts; quaternary ammonium salts such as benzyltriethylammonium acetate; lower fatty acid salts of alkali metals such as potassium acetate and lithium nitrate; dialkylhydroxylamines such as dimethylhydroxylamine and diethylhydroxylamine; and organosilicon compounds containing guanidyl groups.

[0070] In this composition, when component (III-3) is included, the amount is arbitrary and should be sufficient for the curing of the composition. Specifically, 0.01 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, are preferred per 100 parts by mass of component (A). This is because, if this catalyst is essential, setting the catalyst content above the lower limit of the above range allows the resulting composition to cure more thoroughly. On the other hand, setting it below the upper limit of the above range ensures greater storage stability of the resulting composition.

[0071] Furthermore, this composition may contain a silane coupling agent. Examples of silane coupling agents include vinyl-based silane coupling agents, epoxy-based silane coupling agents, acrylic-based silane coupling agents, and long-chain alkyl-based silane coupling agents, with decyltrimethoxysilane, which is a long-chain silane coupling agent, being preferred. The content of the silane coupling agent is preferably 0.1 to 5 parts by mass per 100 parts by mass of spherical aluminum oxide powder. If it is 0.1 parts by mass or more, it is a processing amount that can exhibit an effect as a surface treatment agent for (B) spherical aluminum oxide, and if it is 5 parts by mass or less, it is an economical processing amount for (B) spherical aluminum oxide.

[0072] Furthermore, the composition may also contain, as long as it does not impair the objectives of the present invention, other optional components such as fillers such as zinc oxide, fumed silica, precipitated silica, and fumed titanium oxide; fillers whose surface has been hydrophobized with an organosilicon compound; adhesion promoters such as 3-glycidoxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane; and other pigments, dyes, fluorescent dyes, heat-resistant additives, flame retardants such as triazole compounds, and plasticizers. The above components are preferably present in an amount of 0.1 to 10.0% by mass of the total composition, and more preferably in an amount of 0.5 to 5.0% by mass.

[0073] If the composition is curable, the method of curing it is not limited. For example, the composition may be left at room temperature (20-25°C) after molding, or heated to 40-200°C after molding. In particular, it is preferable that the composition is addition-curable and cured at 15-200°C by a hydrosilylation reaction. The curing time is not particularly limited and can be appropriately selected depending on the purpose, but 30 minutes to 24 hours is preferred. Furthermore, the properties of the silicone rubber obtained in this way are not limited, but examples include gel-like, low-hardness rubber-like, or high-hardness rubber-like.

[0074] [Manufacturing Method] The composition of the present invention can be prepared by mixing predetermined amounts of each of the above components. For example, the process may include a step of mixing so that the volume ratio of component (B):(C) is 5:5 to 9.5:0.5, and components (A) to (E) and other optional components may be mixed.

[0075] [Thermally Conductive Silicone Composition] The thermal conductivity of the thermally conductive silicone composition (cured product) is preferably 1.2 W / (m·K) or higher, more preferably 1.5 W / (m·K) or higher, and even more preferably 1.8 W / (m·K) or higher, according to the hot disk method in accordance with ISO 22007-2. The upper limit is not particularly limited and may be higher, but considering the handling of the composition, it is preferably less than 5.5 W / (m·K), preferably less than 5.2 W / (m·K), and more preferably less than 5.0 W / (m·K). The measurement temperature is 25°C. For measuring the thermal conductivity of the composition in this invention, for example, a device manufactured by Kyoto Electronics Corporation, product name "TPS 2500 S", can be used.

[0076] Furthermore, the viscosity of the thermally conductive silicone composition at 25°C is preferably 30 to 800 Pa·s, and more preferably 100 to 600 Pa·s, when measured with a spiral viscometer at a rotation speed of 10 rpm. The viscosity of the composition of the present invention can be measured using a spiral viscometer, for example, the Malcolm Type PC-10AA. The thermally conductive silicone composition of the present invention has excellent storage properties (viscosity stability) and thermal conductivity, and insulation properties can also be expected.

[0077] [Cured product] If the silicone composition is curable, a cured product can be obtained by curing it using the method described above, and a silicone elastomer molded product can be obtained. The properties of the silicone rubber obtained in this way are not limited, but examples include gel-like, low-hardness rubber-like, or high-hardness rubber-like. The cured thickness is preferably 150 μm or more. There is no particular upper limit, but considering the size of the heat-generating electronic component using this composition, 5 mm or less is preferred. The hardness of the cured product is preferably 15 to 85, and more preferably 20 to 80, using the method described in the examples.

[0078] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0079] The components used are listed below. Note that Me represents a methyl group and Vi represents a vinyl group, and the bond order of the siloxane units is not considered. The rotational viscosity at 25°C was measured using a BM-type viscometer or a BH-type viscometer (manufactured by Tokyo Keiki Co., Ltd.), and the kinematic viscosity at 25°C was measured using an Ostwald viscometer.

[0080] First, the following components were prepared. In the formula, Me represents a methyl group. (A) Component A-1: ​​kinematic viscosity (25°C) of 400 mm 2 Dimethylpolysiloxane A-2: KF-54, manufactured by Shin-Etsu Chemical Co., Ltd., has a specific gravity (25°C) of 0.98, is capped at both ends with dimethylvinylsilyl groups, and has a Vi group content of 0.018 mol / 100g, has a specific gravity (25°C) of 1.07, and a kinematic viscosity (25°C) of 400 mm². 2 / s molecular chain trimethylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane copolymer A-3: KF-50-1,000cs manufactured by Shin-Etsu Chemical Co., Ltd., specific gravity (25°C) is 1.00, and kinematic viscosity (25°C) is 1,000 mm 2 / s molecular chain trimethylsiloxy group sealed dimethylsiloxane / diphenylsiloxane copolymer

[0081] (B) Components: Spherical aluminum oxide having the properties shown in the table below (specific gravity 3.98)

[0082] The coarse particle content shown here refers to the proportion of coarse particles measuring 96 to 150 μm relative to the entire particle size distribution obtained by laser diffraction-type particle size distribution analysis.

[0083] (C) Component: Irregularly shaped aluminum oxide powder having the properties shown in the table below (specific gravity: 3.98)

[0084]

[0085] (D) Component D-1: Represented by the following formula, with a specific gravity (25°C) of 0.97 and a kinematic viscosity (25°C) of 0.03 mm². 2 / s organopolysiloxane

[0086]

[0087] (E) Components E-1: IXE-100, a cation exchange type ion trap agent with a bulk density of 0.52 (25°C) and supported with Zr element (manufactured by Toagosei Co., Ltd.) E-2: IXEPLAS-A1, a dual ion exchange type ion trap agent with a bulk density of 0.25 (25°C) and supported with Zr, Mg, and Al elements (manufactured by Toagosei Co., Ltd.) e-3 (comparative product): IXE-500, an anion exchange type ion trap agent with a bulk density of 0.73 (25°C) and supported with Bi element (manufactured by Toagosei Co., Ltd.)

[0088] (F) Component F-1: Represented by the following formula, with a specific gravity (at 25°C) of 0.97 and a kinematic viscosity (at 25°C) of 28 mm². 2 / s organohydrogenpolysiloxane, where the order of siloxane bonding is irrelevant.

[0089] F-2: Represented by the following formula, with a specific gravity (at 25°C) of 0.97 and a kinematic viscosity (at 25°C) of 17 mm². 2 / s organohydrogenpolysiloxane

[0090] (G) Component G-1: Chloroplatanic acid-1,3-divinyltetramethyldisiloxane complex with a specific gravity (25°C) of 1.00 and a platinum concentration of 1% by mass.

[0091] (H) Component H-1: Specific gravity (25°C) is 0.92, and it is a 50% toluene solution of 1-ethynyl-1-cyclohexanol.

[0092] [Examples and Comparative Examples] The above components (A) to (H) were mixed in the amounts shown in Table 1 as follows to obtain the compositions. Specifically, components (A), (B), (C), and (D) were placed in the amounts shown in Table 1 into a 5-liter gate mixer (manufactured by Inoue Seisakusho Co., Ltd., product name: 5-liter planetary mixer) and degassed and heated and mixed at 150°C for 2 hours. After that, it was cooled to room temperature (25°C), component (G) was added and mixed at room temperature (25°C) until homogeneous, and then component (H) was added and mixed at room temperature (25°C) until homogeneous. Furthermore, components (E) and (F) were added and degassed and mixed at room temperature until homogeneous. The viscosity, initial hardness, hardness after degradation, and thermal conductivity of the compositions obtained in this way were evaluated by the methods shown below. The results are shown in the table below.

[0093] [Viscosity Evaluation] The initial viscosity of the composition is shown as the value at 25°C, and was measured using a Malcolm viscometer (Type PC-10AA, rotation speed 10 rpm).

[0094] [Initial Hardness Evaluation] The composition was poured into a mold to achieve a cured thickness of 6 mm and cured at 100°C for 1 hour. Next, two 6 mm thick cured pieces were stacked and measured using an Asker C hardness tester.

[0095] [Hardness Evaluation After Accelerated (Degradation)] The composition was accelerated at 40°C for 7 days. Then, the composition was poured into a mold to achieve a cured thickness of 6 mm and cured at 100°C for 1 hour. Next, two 6 mm thick cured pieces were stacked and measured using an Asker C hardness tester. If the difference between the initial hardness and the hardness after degradation was 10 points or more, it was determined that curing delay had occurred and the shelf life of the composition could not be ensured.

[0096] [Thermal Conductivity Evaluation] The thermal conductivity of a 6mm cured sample of an addition-curing type thermal conductive silicone grease composition was measured at 25°C using a hot disk method thermophysical property measurement device TPA-501 manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0097]

[0098]

[0099]

[0100]

Claims

1. (A) Organopolysiloxane (excluding component (D)), (B) Average sphericity of 0.8 or higher, 30 hydroxyl groups / nm 2 The following are the characteristics of the spherical aluminum oxide powder, (B) having an average particle size of 8 μm or more and less than 50 μm, with the proportion of coarse particles of 96 to 150 μm in the laser diffraction particle size distribution being 0.1 to 30% by mass of the total component, (C) an amorphous aluminum oxide powder with an average particle size of 0.1 to 5 μm, and (D) the following general formula (1) -SiR 11 (3-α) (OR 12 ) α (1) (wherein, R 11 R is an unsubstituted or substituted monovalent hydrocarbon group, 12 A thermally conductive silicone composition comprising: (A) an organopolysiloxane having a viscosity of 0.01 to 30 Pa·s at 25°C, wherein (A) is independently selected from alkyl groups having 1 to 8 carbon atoms and acyloxy groups, and α is 1, 2, or 3; (E) an ion trapping agent selected from cation exchange type and dual ion exchange type, on which one or more elements selected from Zr, Bi, Sb, Mg, and Al are supported: 0.01 to 10 parts by mass per 100 parts by mass of component (A), wherein the volume ratio of the blending ratio of component (B):(C) is 5:5 to 9.5:0.

5.

2. The thermal conductive silicone composition according to claim 1, characterized in that the total amount of component (B) and component (C) is 65 to 80% by volume in the thermal conductive silicone composition, the thermal conductivity of the thermal conductive silicone composition at 25°C is 1.2 W / (m·K) or more and less than 5.5 W / (m·K) in the hot disk method in accordance with ISO 22007-2, and the viscosity at 25°C is 30 to 800 Pa·s when measured by a spiral viscometer at a rotation speed of 10 rpm.

3. The high thermal conductivity silicone composition according to claim 1, which is curable by addition reaction, organic peroxide, or condensation reaction.

4. A cured product obtained by curing the high thermal conductivity silicone composition according to claim 1 at 15 to 200°C via a hydrosilylation reaction.

5. A method for producing a thermally conductive silicone composition according to any one of claims 1 to 3, comprising the step of mixing the above-mentioned component (B) and component (C) such that the volume ratio of the blending ratio ((B):(C)) is 5:5 to 9.5:0.5.

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