TWI757112B - Thermally conductive composition and method for producing the same - Google Patents

Abstract

The present invention provides a thermally conductive composition and a method for producing the same, wherein the thermally conductive composition comprises a base polymer, an adhesive polymer and thermally conductive particles, and has a thermal conductivity of 0.3 W/m·K or more, and has thermal conductivity The particles include inorganic particles (a) having a specific surface area of 1 m ² /g or less, and the inorganic particles (a) are covered with the above-mentioned adhesive polymer. The production method includes: mixing an adhesive polymer with inorganic particles (a) having a specific surface area of 1 m ² /g or less, and coating the inorganic particles (a) with the adhesive polymer; a primary mixing step; adding base polymer and a secondary mixing step of mixing; and a step of hardening it. Thereby, the thermal conductivity is higher, the compression resilience is higher, and the interface peeling caused by the stress is reduced.

Description

Thermally conductive composition and method for producing the same

The present invention relates to a thermally conductive composition that reduces interfacial peeling caused by stress and a method for producing the same.

In recent years, the performance of semiconductors such as CPU has improved significantly, and the heat generation has also increased significantly. Therefore, a heat sink is installed in electronic components such as heat generation, and a thermally conductive sheet is used in order to improve the adhesion between the semiconductor and the heat sink. However, in recent years, along with the miniaturization and high performance of equipment, high thermal conductivity, low constant load value and soft properties are required for thermally conductive sheets. Patent Document 1 proposes to improve compressibility, insulating properties, thermal conductivity, and the like by setting the viscosity of the thermally conductive polysiloxane composition before curing to 800 Pa·s or less at 23°C. Furthermore, in recent years, thermally conductive compositions containing polysiloxane resins have been proposed as heat sink polysiloxanes for hybrid vehicles, electric vehicles, fuel cell vehicles, and the like (Patent Documents 2 to 3). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2013-147600 [Patent Document 2] Japanese Patent Laid-Open No. 2014-224189 [Patent Document 3] Japanese Patent Laid-Open No. 2019-009237

[The problem to be solved by the invention]

However, the conventional thermally conductive composition has a problem that if inorganic particles with a small specific surface area are added to improve thermal conductivity, interfacial peeling occurs between the inorganic particles and the polymer due to stress. In order to solve the above-mentioned conventional problems, the present invention provides a thermally conductive composition having high thermal conductivity, high compressive rebound force, and reducing interfacial peeling caused by stress, and a manufacturing method thereof. [Technical means to solve the problem]

The thermally conductive composition of the present invention comprises a base polymer, an adhesive polymer and thermally conductive particles, and is characterized in that the thermally conductive composition has a thermal conductivity of 0.3 W/m·K or more, and the thermally conductive particles contain a ratio of The inorganic particles (a) having a surface area of 1 m ² /g or less, and the inorganic particles (a) are covered with the adhesive polymer.

The method for producing a thermally conductive composition of the present invention is to produce the above-mentioned thermally conductive composition, and comprises: mixing an adhesive polymer and inorganic particles (a) having a specific surface area of 1 m ² /g or less, A primary mixing step of coating the inorganic particles (a) with a followable polymer; a secondary mixing step of adding a base polymer and mixing; and a step of hardening it. [Effect of invention]

The present invention can provide a thermally conductive composition and a method for producing the same, wherein the thermally conductive composition has a thermal conductivity of 0.3 W/m·K or more, and the thermally conductive particles include inorganic particles with a specific surface area of 1 m ² /g or less ( a), the inorganic particles (a) are covered with the adhesive polymer, whereby the thermal conductivity is high, the compression resilience is also high, and the interface peeling caused by the stress is reduced. Moreover, the production method of the present invention can efficiently and rationally produce the thermally conductive composition of the present invention by mixing the adhesive polymer with the inorganic particles (a) having a specific surface area of 1 m ² /g or less. , and the first mixing step of coating the inorganic particles (a) with the above-mentioned adhesive polymer; the second mixing step of adding and mixing the base polymer; and the step of hardening.

Generally speaking, it is known that inorganic particles with small specific surface area such as large particle size inorganic particles are not easy to obtain: the above-mentioned inorganic particles are caused by surface treatment process or integral blending with silane coupling agent, etc. The effect of improving the interface with the polymer. Therefore, the interface between the inorganic particles and the polymer is easily peeled off, and the occurrence of cracks becomes a problem, and the peeling of the cracks due to stress becomes a starting point. Therefore, the inventors of the present invention found that when an adhesive polymer is added, the inorganic particles (a) having a specific surface area of 1 m ² /g or less are first mixed with the adhesive polymer, and then the inorganic particles (a) exceeding 1 m ² /g are mixed with the adhesive polymer. Mixing the inorganic particles (b) and the base polymer is effective in suppressing cracks. The present invention has been completed based on such a concept. In this specification, inorganic particles of 1 m ² /g or less are referred to as inorganic particles (a), and inorganic particles of more than 1 m ² /g are referred to as inorganic particles (b).

The present invention is a thermally conductive composition comprising a base polymer, an adhesive polymer, and thermally conductive particles. The thermal conductivity of the above-mentioned thermally conductive composition is 0.3 W/m·K or more, preferably 0.5 W/m·K or more, more preferably 1 W/m·K or more, and preferably 15 W/m·K or more. the following. Moreover, it is electrical insulating property.

The thermally conductive particles of the present invention include inorganic particles (a) having a specific surface area of 1 m ² /g or less. The preferred specific surface area of the inorganic particles (a) is 0.1 to 1 m ² /g, more preferably 0.1 to 0.5 m ² /g. In addition, the inorganic particles (a) are covered with an adhesive polymer. When the inorganic particles (a) and the adhesive polymer are first mixed, the inorganic particles (a) are covered with the adhesive polymer.

The above-mentioned base polymer and adhesive polymer are preferably polysiloxane polymers. Polysiloxane polymers have higher heat resistance, and there is less concern about deterioration or decomposition due to heat test.

The above-mentioned adhesive polymer preferably has a tensile shear bond strength with an aluminum plate of 50 N/cm ² or more. More preferably, it is 80 N/cm ² or more, and still more preferably 100 N/cm ² or more. The upper limit is preferably 800 N/cm ² or less, more preferably 500 N/cm ² or less, and still more preferably 300 N/cm ² or less.

The above-mentioned adhesive polymer preferably includes methylhydrogenpolysiloxane, epoxy group-containing alkyltrialkoxysilane, and cyclic polysiloxane oligomer. Thereby, the adhesiveness with the inorganic particle (A) can be maintained high.

The above-mentioned base polymer is preferably an addition-hardening polysiloxane polymer. This is because the addition hardening type is easier to control than the peroxide hardening type and the condensation hardening type, and does not generate by-products. In addition, in the condensation hardening type, the internal hardening may become insufficient. Therefore, an addition hardening type is preferable.

It is preferable that the said thermally conductive composition further contains polysiloxane oil. By adding the adhesive polymer, the viscosity of the material before hardening increases, or the hardness of the hardened product becomes hard. Therefore, by adding polysiloxane oil, the viscosity of the material before hardening is reduced, and the workability is improved. Moreover, the hardened|cured material also becomes soft. From the aspect of hardenability and workability, the addition amount of the polysiloxane oil is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the base polymer component.

The thermally conductive particles are preferably at least one selected from the group consisting of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, and silica. The reason is that these particles have high thermal conductivity and excellent electrical insulating properties, and are easy to use as a raw material for thermally conductive composition sheets.

The above-mentioned thermally conductive composition is preferably formed into a sheet. It is easy to use if it is formed into a sheet. In addition to sheets, it can also be made into pouring material. Casting material is synonymous with cast molding material (cast material). In the case of making a pouring material, it is set in an unhardened state, and it is hardened after casting molding.

It is preferable to contain 100-3000 weight part of thermally conductive particles with respect to 100 weight part of matrix components. Thereby, the thermal conductivity of the thermally conductive composition sheet becomes 0.3 W/m·K or more. The amount of the thermally conductive particles is preferably 400 to 3000 parts by weight, more preferably 800 to 3000 parts by weight, relative to 100 parts by weight of the matrix component. Moreover, it is preferable to set it as 10-90 weight part of inorganic particles (a) whose specific surface area is 1 m ² /g or less when the total amount of thermally conductive particles is 100 parts by weight. In the above, the matrix component refers to the mixture of base polymer, adhesive polymer and polysiloxane oil.

The above-mentioned thermally conductive particles may be surface-treated with a silane compound, a titanate compound, an aluminate compound, or a partial hydrolyzate thereof. Thereby, the deactivation of the hardening catalyst or the crosslinking agent can be prevented, and the storage stability can be improved.

The thermally conductive composition of the present invention is preferably obtained by crosslinking a composite of the following composition. 1. The primary mixing step The primary mixture is prepared by mixing the adhesive polymer and the inorganic particles (a) having a specific surface area of 1 m ² /g or less to coat the inorganic particles (a) with the adhesive polymer. The addition amount of the adhesive polymer is preferably 5 to 35 parts by weight with respect to 100 parts by weight of the base polymer. The adhesive polymer preferably includes methylhydrogenpolysiloxane, epoxy-containing alkyltrialkoxysilane and cyclic polysiloxane oligomer. Examples of epoxy-containing alkyltrialkoxysilanes include γ-glycidoxypropyltrimethoxysilane represented by the following chemical formula (Chem. 1), and examples of cyclic polysiloxane oligomers include the following Octamethylcyclotetrasiloxane represented by chemical formula (Chem. 2). The thermally conductive particles are preferably added in an amount of 400 to 3000 parts by weight with respect to 100 parts by weight of the matrix component. The inorganic particle (a) having a specific surface area of 1 m ² /g or less is preferably 10 to 90 parts by weight when the total amount of the thermally conductive particles is 100 parts by weight.

[hua 1]

[hua 2]

2 Secondary mixing steps Next, the primary mixture, the base polymer, the catalyst, the inorganic particles (b), and other additives other than the catalyst are added and mixed, and the sheet is formed and cured. The base polymer contains the following base polymer component (component A), crosslinking component (component B), and catalyst component (component C).

Hereinafter, each component to be mixed in the secondary mixing step will be described. (1) Base polymer component (component A) The base polymer component is an organopolysiloxane containing two or more alkenyl groups bonded to silicon atoms in one molecule, and the organopolysiloxane containing two or more alkenyl groups is the polysiloxane rubber of the present invention The main ingredient (base polymer ingredient) in the composition. The organopolysiloxane has two or more alkenyl groups in one molecule, and the alkenyl group is an alkenyl group having 2 to 8 carbon atoms, especially 2 to 6 carbon atoms, such as vinyl group and allyl group, which is bonded to a silicon atom. . The viscosity is preferably 10 to 100,000 mPa·s at 25° C., particularly preferably 100 to 10,000 mPa·s, in terms of workability, hardenability, and the like.

Specifically, an organopolysiloxane containing an average of two or more alkenyl groups in one molecule represented by the following general formula (Chemical 3) and bonded to silicon atoms at both ends of the molecular chain is used. The side chain is a linear organopolysiloxane terminated by an alkyl group. In terms of workability and hardening properties, the viscosity at 25°C is preferably 10 to 100,000 mPa·s. Furthermore, the linear organopolysiloxane may contain a small amount of branched structures (trifunctional siloxane units) in the molecular chain.

[hua 3]

In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond of the same or different types, R ² is an alkenyl group, and k is 0 or a positive integer. Here, as the substituted or unsubstituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond as R ¹ , for example, those having 1 to 10 carbon atoms, especially 1 to 6 carbon atoms are preferable, and specific examples thereof include : methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl and other alkyl groups; Aryl groups such as phenyl, tolyl, xylyl, and naphthyl, aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; Such as halogen atoms, cyano groups, etc. substituted, such as chloromethyl, chloropropyl, bromoethyl, trifluoropropyl and other alkyl groups substituted by halogen, cyanoethyl and the like. As the alkenyl group of R ² , for example, those having 2 to 6 carbon atoms, especially those having 2 to 3 carbon atoms are preferable, and specific examples thereof include vinyl group, allyl group, propenyl group, isopropenyl group, and butyl group. Alkenyl, isobutenyl, hexenyl, cyclohexenyl and the like, preferably vinyl. In general formula (3), k is generally 0 or a positive integer satisfying 0≦k≦10000, preferably an integer satisfying 5≦k≦2000, and more preferably an integer satisfying 10≦k≦1200.

As the organopolysiloxane of the component A, the following organopolysiloxanes, such as vinyl and allyl, can be used in combination with 3 or more, usually 3 to 30, preferably about 3 to 20, in one molecule. Alkenyl groups having 2 to 8 carbon atoms, especially 2 to 6 carbon atoms, such as radicals, are bonded to silicon atoms. The molecular structure may be a linear, cyclic, branched, or three-dimensional network molecular structure. Preferably, the main chain is composed of repeating units of diorganosiloxane, and the two ends of the molecular chain are capped with triorganosiloxane groups, and the viscosity at 25°C is 10-100,000 mPa·s, especially 100-10,000 mPa·s The linear organopolysiloxane.

The alkenyl group may be bonded to any part of the molecule. For example, it may include those bonded to the silicon atom at the end of the molecular chain or at the non-terminal (middle of the molecular chain) of the molecular chain. Among them, it is preferable to have 1 to 3 alkenyl groups on the silicon atoms at both ends of the molecular chain represented by the following general formula (Chemical 4) in terms of workability, hardenability, etc. The alkene bonded to the silicon atom at the end of the chain has at least one alkenyl bonded to the silicon atom at the non-terminal (middle of the molecular chain) of the molecular chain when the total number of the two ends is less than 3 (for example, as diorganosiloxane) (substituents in the alkane unit) linear organopolysiloxane), and the viscosity at 25°C as described above is 10-100,000 mPa·s. Furthermore, the linear organopolysiloxane may contain a small amount of branched structure (trifunctional siloxane unit) in the molecular chain.

[hua 4]

In the formula, R ³ is a substituted or unsubstituted monovalent hydrocarbon group of the same or different kinds, and at least one of them is an alkenyl group. R ⁴ is a substituted or unsubstituted monovalent hydrocarbon group of the same or different kinds without an aliphatic unsaturated bond, R ⁵ is an alkenyl group, and l and m are 0 or a positive integer. Here, the monovalent hydrocarbon group of R ³ is preferably one having 1 to 10 carbon atoms, particularly 1 to 6, and specific examples thereof include methyl, ethyl, propyl, isopropyl, and butyl. , isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl and other alkyl groups; phenyl, tolyl, xylyl, naphthyl and other aryl groups; Aralkyl groups such as benzyl, phenylethyl, phenylpropyl; vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, octenyl and other alkenyl groups ; or a part or all of the hydrogen atoms of these groups are replaced by halogen atoms such as fluorine, bromine, chlorine, cyano, etc., such as chloromethyl, chloropropyl, bromoethyl, trifluoropropyl, etc. Substituted alkyl or cyanoethyl, etc.

In addition, the monovalent hydrocarbon group of R ⁴ is also preferably one having 1 to 10 carbon atoms, particularly preferably one having 1 to 6 carbon atoms, and the same as the specific examples of R ¹ described above can be exemplified, but does not include an alkenyl group . As the alkenyl group of R ⁵ , for example, those having 2 to 6 carbon atoms are preferable, and those having 2 to 3 carbon atoms are particularly preferable. Specifically, the same ones as those of R ² in the above formula (Chem. 3) can be exemplified, and preferably vinyl.

l and m are generally 0 or a positive integer satisfying 0<l+m≦10000, preferably 5≦l+m≦2000, more preferably 10≦l+m≦1200, and 0<l/(l+m)≦0.2 , preferably an integer satisfying 0.0011≦l/(l+m)≦0.1.

(2) Crosslinking component (component B) The organohydrogenpolysiloxane of the B component of the present invention functions as a crosslinking agent, and is formed by addition reaction (hydrosilylation) between the SiH group in the component and the alkenyl group in the A component (hydrosilylation). thing. The organohydrogenpolysiloxane may be any one as long as it has two or more hydrogen atoms (ie, SiH groups) bonded to silicon atoms in one molecule, and the molecular structure of the organohydrogenpolysiloxane may be Any of linear, cyclic, branched, and three-dimensional network structures can be used, and the number of silicon atoms in one molecule (ie, the degree of polymerization) is 2 to 1000, especially about 2 to 300.

The position of the silicon atom to which the hydrogen atom is bonded is not particularly limited, and may be the end of the molecular chain or the non-terminal (midway). Moreover, as an organic group other than a hydrogen atom which bonds with a silicon atom, the substituted or unsubstituted monovalent hydrocarbon group which does not have aliphatic unsaturated bond like R1 ^of the said general formula (Formula 3) is mentioned. As the organohydrogen polysiloxane of the B component, the following structures can be exemplified.

[hua 5]

In the above formula, R ⁶ is the same or different kinds of hydrogen, alkyl group, phenyl group, epoxy group, acrylyl group, methacrylyl group, and alkoxy group, and at least two of them are hydrogen. L is an integer of 0-1,000, especially an integer of 0-300, and M is an integer of 1-200.

(3) Catalyst component (component C) The catalyst component of component C is a component that promotes the hardening of the first stage of the composition. As the C component, a catalyst used in the hydrosilation reaction can be used. For example, platinum black, chloroplatinate, chloroplatinic acid, reactant of chloroplatinic acid and monohydric alcohol, complex of chloroplatinic acid and olefins or vinylsiloxane, diacetoxyacetic acid Platinum-based catalysts such as platinum, palladium-based catalysts, rhodium-based catalysts and other platinum-group metal catalysts. The blending amount of component C may be an amount required for curing, and it can be appropriately adjusted according to a desired curing speed and the like. It is preferable to add 0.01-1000 ppm by metal atomic weight with respect to A component.

(4) Thermally Conductive Particles When thermally conductive particles are added in the secondary mixing step, the inorganic particles (b) having a specific surface area exceeding 1 m ² /g are used. The inorganic particle (a) having a specific surface area of 1 m ² /g or less is preferably 10 to 90 parts by weight when the total amount of the thermally conductive particles is 100 parts by weight. The remainder is preferably used as inorganic particles (b). Thereby, the thermally conductive inorganic particles of small particle diameter are filled between the large particle diameters, and the filling can be made in a state close to the most densely packed state, and the thermal conductivity becomes high.

The thermally conductive particles to be mixed in the primary and secondary mixing steps are preferably at least one selected from the group consisting of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, and silicon dioxide. Various shapes, such as spherical shape, scale shape, and polyhedron shape, can be used. In the case of using alumina, α-alumina having a purity of 99.5 mass % or more is preferred. The specific surface area is the BET specific surface area, and the measurement method is based on JIS R1626. When the average particle diameter is used, the measurement of the particle diameter is performed by measuring D50 (median particle diameter) of the cumulative particle size distribution on a volume basis by a laser diffraction light scattering method. As this measuring device, there is, for example, a laser diffraction/scattering particle distribution measuring device LA-950S2 manufactured by Horiba Corporation.

The inorganic particles (b) mixed in the secondary mixing step are preferably made of R _a Si(OR') _3-a (R is a substituted or unsubstituted organic group having 1 to 20 carbon atoms, and R' is A silane compound represented by an alkyl group having 1 to 4 carbon atoms, a is 0 or 1) or a partial hydrolyzate thereof is surface-treated. About R _a Si(OR') _3-a (R is a substituted or unsubstituted organic group having 1 to 20 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) The alkoxysilane compound (hereinafter referred to as "silane"), for example, there are methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane Oxysilane, Hexyltrimethoxysilane, Hexyltriethoxysilane, Octyltrimethoxysilane, Octyltriethoxysilane, Decyltrimethoxysilane, Decyltriethoxysilane, Dodecane trimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethyl Silane compounds such as oxysilanes. The above-mentioned silane compounds may be used alone or in combination of two or more. Alkoxysilanes and mono-terminal silanolsiloxanes may also be used in combination as surface treatment agents. The so-called surface treatment here includes adsorption and the like in addition to covalent bonding.

(5) Polysiloxane oil The polysiloxane oil is preferably polydimethylsiloxane-based. The viscosity of the polysiloxane oil measured by a rotational viscometer is preferably 10-10000 mPa·s (25°C).

(6) Other additives Components other than the above may be blended into the composition of the present invention as necessary. For example, inorganic pigments such as titanate may be added, and alkyltrialkoxysilanes and the like may be added for surface treatment of inorganic particles. Alkoxy-containing polysiloxane may also be added as a material added for surface treatment of inorganic particles and the like. [Example]

Hereinafter, it demonstrates using an Example. The present invention is not limited to the Examples. <Thermal conductivity> The thermal conductivity of the thermally conductive composition was measured by Hot Disk (according to ISO 22007-2). In this thermal conductivity measuring apparatus 11, as shown in FIG. 1A, a sensor 12 made of a polyimide film is sandwiched between two thermally conductive composition samples 13a and 13b, and constant power is applied to the sensor 12 to make a constant generate heat, and analyze the thermal characteristics according to the temperature rise value of the sensor 12 . The tip 14 of the sensor 12 is 7 mm in diameter, and as shown in FIG. 1B , has a double helical structure of electrodes, and an electrode 15 for current application and an electrode for resistance value (electrode for temperature measurement) 16 are arranged at the lower part. The thermal conductivity was calculated by the following formula (Equation 1).

λ：熱傳導率（W /m ·K） P ₀：恆定功率（W） r：感測器之半徑（m） τ：

α：試樣之熱擴散率（m ²/s） t：測定時間（s） D（τ）:經無因次（dimensionless）化之τ之函數 ∆T（τ）：感測器之溫度上升（K） ＜黏度＞ 依據JIS K7117-1：1999 測定裝置：布氏黏度計C型（主軸號根據黏度而改變） 旋轉速度：10 RPM 測定溫度：25℃ ＜硬度＞ 對依據JIS K7312之Asker C硬度進行測定。 ＜拉伸剪切接著強度＞ 利用依據JIS K6850之下述方法進行測定。說明圖示於圖2。 測定器：東洋Baldwin公司製造之UTM-4-100 接著面積：L1＝3 cm、L2＝2.5 cm 試片：準備1對鋁合金板21、22藉由聚合物23接著所得者作為試片。以聚合物之厚度成為L3＝0.14 cm之方式進行固定，並使其硬化。 試驗方法：使用上述試片進行拉伸試驗，將斷裂時之力之最大值（N）設為接著斷裂荷重（斷裂點之荷重），將除以接著面積（3 cm×2.5 cm）所得之值設為拉伸剪切接著強度（N/cm ²）。 硬化條件：室溫24小時 拉伸速度：500 mm/min ＜拉伸強度＞ 利用依據JIS K 6521之下述方法進行測定。 測定器： A&D公司製造之RTG-1210（荷重元　1 kN） 試片：JIS K6251 2號型 啞鈴狀 試驗方法：使用上述試片進行拉伸試驗，對斷裂時之拉伸強度（MPa）進行測定。 拉伸速度：500 mm/min ＜壓縮反彈力＞ 測定器：Aikoh Engineering公司製造之MODEL1310NW（荷重元　1 kN） 試片：直徑16 mm 鋁板：22.8 mm×22.8 mm×4 mmt SUS板：直徑13.9 mm×4 mmt 壓縮速度：10 mm/min 試驗方法：以於鋁板上裝載試片，並於其上使SUS板重疊之狀態進行壓縮直至0.4 mm，將靜置10分鐘時之荷重值設為壓縮反彈力（N）。 [Number 1]

λ: Thermal conductivity (W / m · K) P ₀ : Constant power (W) r: Radius of the sensor (m) τ:

α: Thermal diffusivity of the sample (m ² /s) t: Measurement time (s) D(τ): Function of dimensionless τ ΔT(τ): Temperature rise of the sensor (K) <Viscosity> According to JIS K7117-1: 1999 Measuring device: Brookfield viscometer Type C (spindle number varies according to viscosity) Rotation speed: 10 RPM Measurement temperature: 25°C <Hardness> For Asker C according to JIS K7312 Hardness was measured. <Tensile Shear Bonding Strength> It was measured by the following method based on JIS K6850. An explanatory diagram is shown in FIG. 2 . Measuring device: UTM-4-100 manufactured by Toyo Baldwin Co., Ltd. Adhering area: L1=3 cm, L2=2.5 cm Test piece: A pair of aluminum alloy plates 21 and 22 were prepared by bonding with polymer 23 as a test piece. It fixed so that the thickness of a polymer might become L3=0.14 cm, and it hardened. Test method: Use the above-mentioned test piece for tensile test, set the maximum value (N) of the force at break as the subsequent breaking load (the load at the breaking point), and divide it by the value obtained by the bonding area (3 cm×2.5 cm). Let it be the tensile shear bond strength (N/cm ² ). Hardening conditions: Room temperature for 24 hours Tensile speed: 500 mm/min <Tensile strength> It was measured by the following method based on JIS K 6521. Measuring device: RTG-1210 (load element 1 kN) manufactured by A&D Company Test piece: JIS K6251 No. 2 dumbbell test method: Use the above test piece for tensile test, and measure the tensile strength (MPa) at break . Tensile speed: 500 mm/min <Compression rebound force> Measuring device: MODEL1310NW (load element 1 kN) manufactured by Aikoh Engineering Co., Ltd. Specimen: Diameter 16 mm Aluminum plate: 22.8 mm×22.8 mm×4 mmt SUS plate: Diameter 13.9 mm ×4 mmt Compression speed: 10 mm/min Test method: Load a test piece on an aluminum plate, and compress the SUS plate on top of it to 0.4 mm, and set the load value at rest for 10 minutes as the compression rebound Force (N).

(Example 1) (1) Adhesive polymer 20 to 30 mass % of methyl hydrogen polysiloxane, 1 to 10 mass % of γ-glycidoxypropyltrimethoxysilane represented by the above chemical formula (Chemical 1), and 1 to 10 mass % of the above chemical formula (Formula 2) are used. 0.1-1 mass % of octamethylcyclotetrasiloxane and 1-10 mass % of carbon black, and the remainder is a commercially available adhesive polymer of polysiloxane. The tensile shear bond strength of the adhesive polymer to the aluminum plate is shown in Table 1. (2) Base polymer A commercially available two-pack room temperature curing polysiloxane polymer was used as the base polymer. A base polymer component and a platinum-based metal catalyst are pre-added to the liquid A of the two-component room temperature-curing polysiloxane polymer, and a base polymer component and a cross-linking component are pre-added to the B liquid. The tensile shear bond strength of the base polymer to the aluminum plate is shown in Table 1.

[Table 1] Tensile shear bond strength (N/cm ² ) adhesive polymer 112 base polymer 27

(3) Polysiloxane oil Dimethyl polysiloxane-based polysiloxane oil with a viscosity of 97 mPa·s measured by a rotational viscometer was used. (4) Thermally conductive particles Alumina shown in Table 2 was used as the thermally conductive particles.

[Table 2] Thermally Conductive Particles Average particle size (μm) Specific surface area (m ² /g) shape Alumina powder A 35 0.2 true spherical Alumina powder B 2.1 1.8 smash Alumina powder C 0.3 7.4 indeterminate

(5) Production of the compound In one mixing step, the above-mentioned adhesive polymer and the alumina powder A were thoroughly mixed to prepare a mixture 1 . Next, in the secondary mixing step, the base polymer, the alumina powder B, the alumina powder C, the platinum-based catalyst, and the cross-linking component are added to the mixture 1 and mixed sufficiently to prepare the mixture 2 . (6) Forming of thermally conductive composition The above-mentioned mixture 2 was sandwiched between polyester (PET) films, rolled into a sheet with a thickness of 2 mm, and cured at 100° C. for 2 hours.

(Comparative Example 1) The same procedure as in Example 1 was carried out, except that all the materials were mixed at the same time in the preparation step of the above-mentioned composite. The conditions and physical properties of the thermally conductive composition obtained as described above are summarized in Table 3-4 and Fig. 3-4. Figures 3-4 are scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) surface photographs. Table 4 shows the results obtained by measuring the Si and Al mass concentrations (mass %) on the surface of the inorganic particles (a) having a specific surface area of 1 m ² /g or less using SEM/EDX.

[table 3] Example 1 (Adhesive polymer and alumina powder A are mixed in one mixing step) Comparative Example 1 (mix all materials at the same time) Base polymer (g) 65 65 Silicone oil (g) 15 15 Adhesive polymer (g) 20 20 Platinum series catalyst (g) 2 2 Alumina powder A (g) 770 770 Alumina powder B + Alumina powder C (g) 432 432 Asker C hardness 27 27 Tensile strength (kPa) 180 150 Compression rebound force (N) 341 133 Thermal conductivity (W/m・K) 3.4 3.4

[Table 4] Example 1 Comparative Example 1 Inorganic particle (a) surface mass concentration, Si (mass %): X 5.9 2.7 Inorganic particle (a) surface mass concentration, Al (mass %): Y 21.5 32.2 The ratio of Si to Al (%): (X/Y)×100 27 9 surface condition image 3 Figure 4

According to Table 3, the tensile strength and compressive rebound force of Example 1 are higher than those of Comparative Example 1. The reason for this is considered to be that the adhesive force between the surface of the inorganic particle (a) and the adhesive polymer is high. It can be seen from Table 4 that the ratio of Si to Al in Example 1 is higher than that in Comparative Example 1. It means that there are many polymer components on the surface of large particles. In addition, from the image data of scanning electron microscope/energy dispersive X-ray spectrometry (SEM/EDX), it can also be confirmed that the inorganic particles (a) of Comparative Example 1 ( FIG. 4 ) are exposed. In contrast to this, Example 1 ( The surface of the inorganic particle (a) in Fig. 3) is covered with a polymer component. [Industrial Availability]

The thermally conductive composition of the present invention is useful as a heat sink between a heat generating part and a heat sink part for electronic parts such as LEDs and home appliances, information communication modules including optical communication equipment, and vehicle applications. Furthermore, it is useful as a heat sink for electronic components including semiconductors.

11: Thermal conductivity measuring device 12: Polyimide film sensor 13a, 13b: Thermally conductive composition samples 14: Sensor head end 15: Electrodes for applying current 16: Electrode for resistance value (electrode for temperature measurement) 21,22: Aluminum alloy plate 23: Polymer

[Fig. 1] Figs. 1A-B are explanatory diagrams showing a method of measuring thermal conductivity used in an example of the present invention. [Fig. [ Fig. 2] Fig. 2 is an explanatory view showing a method of measuring tensile shear bond strength used in an example of the present invention. [Fig. 3] Fig. 3 is a scanning electron microscope/energy dispersive X-ray spectrometry (SEM/EDX) fracture surface image data of the thermally conductive composition sheet obtained in Example 1 of the present invention. [ Fig. 4] Fig. 4 is a scanning electron microscope/energy dispersive X-ray spectrometry (SEM/EDX) fracture surface image data of the thermally conductive composition sheet obtained in Comparative Example 1. [Fig.

Claims (11)

A thermally conductive composition comprising a base polymer, an adhesive polymer and thermally conductive particles, wherein the base polymer is an addition-hardening polysiloxane polymer, and the thermal conductivity of the thermally conductive composition is is 0.3 W/m·K or more, the thermally conductive particles include inorganic particles (a) having a specific surface area of 1 m ² /g or less, and the inorganic particles (a) are formed from the adhesive polymer before the thermally conductive composition is formed. Covered, the above-mentioned adhesive polymer includes methyl hydrogen polysiloxane, epoxy-containing alkyltrialkoxysilane and cyclic polysiloxane oligomer. The thermally conductive composition according to claim 1, wherein the tensile shear bond strength between the adhesive polymer and the aluminum plate is 50 N/cm ² or more. The thermally conductive composition according to claim 1 or 2, wherein the thermally conductive composition further comprises polysiloxane oil. The thermally conductive composition according to claim 3, wherein the amount of the polysiloxane oil is 5 to 30 parts by weight when the base polymer is used as 100 parts by weight. The thermally conductive composition according to claim 1 or 2, wherein the thermally conductive particles are at least one selected from the group consisting of metal oxides, metal hydroxides, metal nitrides and silicon dioxide. The thermally conductive composition according to claim 1 or 2, wherein the thermally conductive composition further comprises inorganic particles (b) having a specific surface area exceeding 1 m ² /g. The thermally conductive composition according to claim 6, wherein the inorganic particles (b) are surface-treated with a silane compound, a titanate compound, an aluminate compound, or a partial hydrolyzate thereof. The thermally conductive composition according to claim 1 or 2, wherein the thermally conductive composition is sheet-molded. The thermally conductive composition according to claim 1 or 2, wherein the adhesive polymer is 5 to 35 parts by weight relative to 100 parts by weight of the base polymer. A method for producing a thermally conductive composition, which is for producing the thermally conductive composition according to any one of claims 1 to 9, and comprising: combining an adhesive polymer with inorganic particles (a) having a specific surface area of 1 m ² /g or less ) mixing and coating the above-mentioned inorganic particles (a) with the above-mentioned adhesive polymer; a second mixing step of adding a base polymer and mixing; and a step of hardening it. The method for producing a thermally conductive composition according to claim 10, wherein inorganic particles (b) having a specific surface area exceeding 1 m ² /g are added in the secondary mixing step.

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