TW202104403A - Thermally conductive resin composition and thermally conductive resin cured product - Google Patents

Abstract

The present invention contains 50-80 vol% of a thermosetting resin component, 5-20 vol% of boron nitride, and 10-45 vol% of a thermally conductive filler other than the boron nitride. The boron nitride is preferably a secondary particle in which scale-like boron nitride primary particles are radially aggregated. This thermally conductive resin composition has a thermally conductive filler having a preferable specific gravity of 2.0-6.0. The present invention is a cured product of said thermally conductive resin composition. Consequently, a highly thermally conductive resin composition and a highly thermally conductive resin cured product, which have high thermal conductivity and a low specific gravity and are effective as a heat dissipation material, are stably provided.

Description

Thermally conductive resin composition and thermally conductive resin cured product

The present invention relates to a thermally conductive resin composition and a cured thermally conductive resin.

Electronic components such as the central processing unit (CPU), driver IC (driver IC), and memory used in electronic devices such as personal computers and mobile phones are becoming smaller and more integrated, and their own heating density is increasing. Increase rapidly. If heat accumulates in electronic parts, the temperature of the electronic parts will rise, which may cause malfunctions and malfunctions. In order to efficiently dissipate heat generated by electronic components to cooling members such as heat sinks, a method has been proposed in which a heat dissipation member with high thermal conductivity is used.

In recent years, the demand for heat dissipation members of lithium-ion batteries for vehicles has been increasing. The specific use positions are the interface between the battery cell and the cell frame and the interface between the battery module and the battery frame. If an excessive load is applied to a battery cell, etc., it will cause poor operation. Therefore, flexibility is required for the heat dissipation member. In addition, for in-vehicle use, long-term reliability in a temperature range from around -40°C, which is the lowest temperature in a cold area, to a high temperature of 150°C or higher, which is the temperature of the heat dissipation member, is required. Furthermore, properties such as flame retardancy and electrical insulation are often required. A heat dissipation material that satisfies all of these characteristics is more suitable for silicon oxide. Therefore, a thermally conductive silicon oxide composition or a hardened product made of silicon oxide and a thermally conductive filler is often used as a heat sink member.

The fuel consumption regulations of automobiles around the world are becoming more and more stringent, and measures are being taken to improve the fuel consumption performance of engines such as miniaturization and high output, and reduction of air resistance. In addition, since fuel consumption deteriorates as the weight of a car increases, it is also expected to reduce the weight of the parts mounted. In particular, in hybrid vehicles and electric vehicles, the scale of the lithium-ion batteries used is large, and the vehicle body is seeking to further reduce the weight. In addition, the amount of heat dissipating members used for heat dissipation of lithium-ion batteries is also very large, and therefore, the weight of the heat dissipating members is also expected to be reduced.

However, in general, the heat dissipation member has a large specific gravity. In particular, the conventionally known composition having high thermal conductivity has a large blending amount of the thermally conductive filler, and therefore the specificity of the composition is large. Therefore, the weight of the heat dissipation member will increase, and the total weight of the vehicle body will also increase, resulting in an increase in fuel consumption. Therefore, technologies for reducing the specific gravity of heat dissipation members are being sought.

As one method, for example, the use of a filler having a small specific gravity and high thermal conductivity can be mentioned. As described in Patent Document 1 and Patent Document 2, a thermally conductive sheet is being developed in which agglomerated secondary particles of boron nitride are dispersed in a resin to improve thermal conductivity. However, the filling rate of boron nitride is high, so the specific composition of the composition is high. In addition, Patent Document 2 describes a method in which agglomerated particles of boron nitride and alumina are combined. However, the filling rate of each filler is not clearly specified, and the fluidity and processability of the composition are not described.

On the other hand, as described in Patent Document 3, a method is disclosed in which hollow particles with a small specific gravity are added to the resin to reduce the specific gravity of the resin. However, most of the hollow particles have low compressive strength. If a manufacturing method such as press-feeding the resin is used, the hollow particles will be broken, making it difficult to reduce the specific gravity of the resin.

As described above, a conventional composition having a high thermal conductivity has a large proportion of the composition due to the large amount of thermally conductive filler blended. In addition, if a material with low compressive strength such as hollow particles is used in order to reduce the specific gravity, a resin composition with the target specific gravity cannot be obtained. [Prior Technical Literature] (Patent Document)

Patent Document 1: Japanese Patent Application Publication No. 2010-157563 Patent Document 2: Japanese Patent Application Publication No. 2011-144234 Patent Document 3: JP 2012-119674 A

[The problem to be solved by the invention] The present invention was developed in view of the above reasons, and its purpose is to stably provide a highly thermally conductive resin composition and a highly thermally conductive resin cured product, which have high thermal conductivity and low specific gravity and are effective as a heat dissipation material. [Technical means to solve the problem]

In order to achieve the above-mentioned problem to be solved, the present invention provides a thermally conductive resin composition containing: 50 to 80% by volume of a thermosetting resin component, 5 to 20% by volume of boron nitride, and 10 to 45% by volume Thermally conductive fillers other than the aforementioned boron nitride.

If it is such a thermally conductive resin composition, it becomes a highly thermally conductive resin composition with high thermal conductivity and low specific gravity.

Preferably, the aforementioned boron nitride is a secondary particle, and the secondary particle is formed by aggregating primary particles of scaly boron nitride into a radial shape.

Since the scaly boron nitride has a layered crystal structure, the thermal conductivity of the crystal plane direction and the layered direction are significantly different, and therefore exhibits anisotropic thermal conductivity. On the other hand, since the primary particles of scaly boron nitride are aggregated into radial secondary particles, they have isotropic thermal conductivity, so when they are made into a thermally conductive resin composition, regardless of the molding method and use form, Both will show stable thermal conductivity.

Preferably, the specific gravity of the aforementioned thermally conductive filler is 2.0 to 6.0. If the specific gravity of the aforementioned thermally conductive filler is 2.0 to 6.0, the specific gravity of the thermally conductive resin composition will further decrease.

The present invention provides a cured thermally conductive resin, which is a cured product of the thermally conductive resin composition described above. The thermally conductive resin cured product is a highly thermally conductive resin cured product, which has high thermal conductivity and low specific gravity, and is effective as a heat dissipation material.

Preferably, the thermal conductivity of the cured thermally conductive resin is 1.0 W/(m·K) or more. With such a thermal conductivity, the heat emitted from the heating element can be sufficiently transferred to the cooling portion, which is preferable.

In addition, it is preferable that the specific gravity of the cured thermally conductive resin is 2.0 or less. If it is such a specific gravity, a sufficient effect of reducing the specific gravity can be obtained, which is preferable.

Preferably, the cured thermally conductive resin of the present invention has a hardness of 60 or less measured by an ASKER C-type hardness tester. With the hardness of such a hardened product, it can closely adhere to the minute irregularities existing in the heat generating part and the cooling part, and the thermal resistance is not too large, so that the heat can be efficiently discharged, which is preferable. [effect]

Since the thermally conductive resin composition and the thermally conductive resin cured product of the present invention can achieve both high thermal conductivity and low specific gravity, they become a highly thermally conductive resin composition and a highly thermally conductive resin cured product, which are effective as heat dissipation materials of.

In addition, the aforementioned thermally conductive resin composition and thermally conductive resin cured product have a thermosetting resin component of 50 to 80% by volume as the base material, which restricts the filling of thermally conductive fillers other than boron nitride and boron nitride. Therefore, the fluidity and processability of the resin composition will be good, and it will show stable thermal conductivity regardless of the molding method and use form.

As mentioned above, it has been sought to develop a highly thermally conductive resin composition and a highly thermally conductive resin cured product, which has high thermal conductivity and low specific gravity, and is effective as a heat dissipation material.

In order to achieve the above-mentioned object, the inventors have made great efforts to conduct research. As a result, they have discovered the following fact: a resin composition and its cured product become a high thermal conductivity resin composition with a small specific gravity and its cured product, which is more suitable as a heat dissipation member. The resin composition contains 50 to 80% by volume of a thermosetting resin component used as a base material, 5 to 20% by volume of boron nitride, and 10 to 45% by volume of thermally conductive fillers other than boron nitride. In addition, the following facts have been found to complete the preferred embodiment of the present invention, that is, by compounding in the following manner, the specific gravity of the highly thermally conductive resin composition and its cured product will be more reduced and the thermal conductivity will be more improved: For boron nitride, primary particles of scaly boron nitride are aggregated into radial secondary particles, and for the aforementioned thermally conductive filler, an inorganic filler having a specific gravity of 2.0 to 6.0 is selected.

In other words, the present invention is a thermally conductive resin composition containing: 50 to 80% by volume of a thermosetting resin component, 5 to 20% by volume of boron nitride, and 10 to 45% by volume of other than the aforementioned boron nitride Thermally conductive filler.

The present invention will be described in detail below, but the present invention is not limited by these. [Thermally conductive resin composition] [Boron Nitride] The boron nitride contained in the thermally conductive resin composition of the present invention is preferably a secondary particle formed by agglomerating primary particles of scaly boron nitride into a radial shape. Particles in such a form will have isotropic thermal conductivity. Therefore, when a thermally conductive resin composition is produced, it will exhibit stable thermal conductivity regardless of the molding method and use form.

The secondary particle size of boron nitride is not particularly limited, but it is preferably a particle size of 10 to 200 μm. In the case of boron nitride with such a secondary particle size, it is easy to disperse it in the resin and easily mix. In addition, when the thermally conductive sheet is manufactured, if the agglomerated secondary particles of boron nitride are too large, the adhesion of the surface will be impaired, and the adhesion to the substrate will be deteriorated, so that the heat cannot be efficiently discharged. Therefore, the secondary particle size of boron nitride is preferably 80% or less of the thickness of the thermally conductive resin layer.

In the present invention, in order to improve the thermal conductivity in the resin composition, it is necessary to contain 5-20% by volume of boron nitride, and preferably 5-15% by volume. If the boron nitride is less than 5% by volume, the thermal conductivity of the thermally conductive resin composition and the cured thermally conductive resin will be insufficient. In addition, if the boron nitride exceeds 20% by volume, the fluidity and moldability of the thermally conductive resin composition will decrease.

[Heat conductive fillers other than boron nitride] The thermally conductive filler other than boron nitride contained in the thermally conductive resin composition of the present invention is preferably inorganic particles having a specific gravity of 2.0 to 6.0. For example: metals such as aluminum and silicon; metal oxides such as aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, and zinc oxide; metal nitrides such as aluminum nitride and silicon nitride; metals such as aluminum hydroxide and magnesium hydroxide Hydroxide; graphite, synthetic diamond, silicon carbide, etc. In particular, aluminum hydroxide and aluminum oxide have a light specific gravity and are excellent in filling properties to resins, so they are more suitable as the aforementioned thermally conductive fillers. These thermally conductive fillers can be used alone or in combination of two or more kinds.

In the present invention, among these, particularly suitable is aluminum hydroxide or aluminum oxide, which has a light specific gravity and is excellent in filling properties to resin.

In the present invention, in order to improve the thermal conductivity in the resin composition, it is necessary to contain 10 to 45% by volume of the aforementioned thermally conductive filler, preferably 10 to 25% by volume. If the aforementioned thermally conductive filler is less than 10% by volume, the thermal conductivity of the thermally conductive resin composition and the cured thermally conductive resin will be insufficient. In addition, if the boron nitride exceeds 45% by volume, the specific gravity of the thermally conductive resin composition and the cured thermally conductive resin will increase. In addition, the fluidity and moldability of the thermally conductive resin composition may decrease.

[Thermosetting resin component] The thermosetting resin used as the base material of the thermally conductive resin composition of the present invention is not particularly limited. For example, silicone resins, phenol resins, urea resins, melamine resins, unsaturated polyester resins, epoxy resins, and polyurethanes can be used. Resin, polyimide resin, etc. In particular, silicone resin is more suitable due to its simple curing method. The thermosetting resin component of the present invention can contain general raw materials of thermosetting resins such as raw materials of these resins before curing, curing agents, and catalysts.

The thermally conductive resin composition of the present invention contains 50 to 80% by volume of a thermosetting resin component. If the thermosetting resin component is less than 50% by volume, the fluidity and moldability of the thermally conductive resin composition will decrease. In addition, if the thermosetting resin component exceeds 80% by volume, the thermal conductivity of the thermally conductive resin composition and the thermally conductive resin cured product will be insufficient. The thermosetting resin component (silicone resin component) will be described in detail below, but the present invention is not limited by these.

[Thermosetting resin component (organopolysiloxane component)] The thermosetting resin component (organopolysiloxane component) used as the base material is not particularly limited, and, for example, a component used as the base material of the silicone composition can be mentioned. For example, the organopolysiloxane used as the main polymer of the addition-curing silicone composition is particularly preferably (A-1) an organopolysiloxane having at least two alkenyl groups in one molecule. As the component (A-1), for example, an organopolysiloxane having a structure represented by the following general formula (1) and having at least two alkenyl groups in one molecule.

式(1)中，R¹ 獨立地表示經取代或未被取代的碳原子數1～18、較佳為1～8的1價烴基，a為1.90～2.05。

In formula (1), R ¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18, preferably 1 to 8 carbon atoms, and a is 1.90 to 2.05.

The component (A-1), particularly the organopolysiloxane having a structure represented by the above general formula (1), preferably has a degree of polymerization of 20 to 12,000, and more preferably has a degree of polymerization of 50 to 10,000.

Examples of R ¹ include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and octadecyl; cyclopentyl , And cycloalkyl such as cyclohexyl; aryl such as phenyl, tolyl, xylyl, and naphthyl; aralkyl such as benzyl, phenethyl, and 3-phenylpropyl; 3,3, Haloalkyl groups such as 3-trifluoropropyl and 3-chloropropyl; alkenyl groups such as vinyl, allyl, butenyl, pentenyl, and hexenyl.

When the aforementioned thermosetting resin component (organopolysiloxane component) used as the base material is (A-1) an organopolysiloxane having at least two alkenyl groups in one molecule, the thermally conductive resin composition of the present invention It can further comprise: the following (A-2) organohydrogen polysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule, (A-3) platinum-based curing catalyst, (A-4) Addition reaction control agent.

(A-2) The organohydrogen polysiloxane, which has at least two hydrogen atoms directly bonded to silicon atoms in one molecule of the component, will react with the component (A-1) to act as a cross-linking agent. The molecular structure is not particularly limited, and various molecular structures such as linear, cyclic, branched, three-dimensional network structure (resin-like), etc. can be used in the past, but it must have two or more in one molecule, preferably Three or more hydrogen atoms (hydrosilyl groups represented by Si-H) directly bonded to silicon atoms, usually 2 to 300, preferably 3 to 200, more preferably 4 to 100 or so Si-H base.

(A-2) The compounding amount of the component is preferably set to the following amount: the number of moles (mol) of the hydrogen atom directly bonded to the silicon atom becomes the number of moles of the alkenyl group derived from the component (A-1) 0.1 to 5.0 times of the amount.

作為上述R² ，除了烯基等脂肪族不飽和基，較佳為碳數1～10的與矽原子鍵結的未被取代的1價烴基，作為此R² 中的未被取代的1價烴基，可舉例如：甲基、乙基、丙基、異丙基、丁基、異丁基、三級丁基、戊基、新戊基、己基、環己基、辛基、壬基、癸基等烷基；苯基、甲苯基、二甲苯基、萘基等芳基；苯甲基、苯乙基、苯基丙基等芳烷基等。特別是，從難燃性的觀點來看，宜為甲基、苯基。此外，b為0.7～2.1，c為0.001～1.0，且為b＋c滿足0.8～3.0的正數，較佳是：b為1.0～2.0，c為0.01～1.0，b＋c為1.5～2.5。Such a component (A-2) is preferably represented by the following general formula (2).

As the above-mentioned R ² , in addition to aliphatic unsaturated groups such as alkenyl groups, an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms bonded to a silicon atom is preferred, as the unsubstituted monovalent hydrocarbon group in R ² Hydrocarbyl groups include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl Alkyl groups such as phenyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenethyl, and phenylpropyl. In particular, from the viewpoint of flame retardancy, a methyl group or a phenyl group is preferable. In addition, b is 0.7 to 2.1, c is 0.001 to 1.0, and b+c is a positive number satisfying 0.8 to 3.0. Preferably, b is 1.0 to 2.0, c is 0.01 to 1.0, and b+c is 1.5 to 2.5.

The platinum-based hardening catalyst of the component (A-3) is a catalyst that promotes the hydrosilylation of the alkenyl group in the component (A-1) and the Si-H group in the component (A-2) Into a reaction. As this addition reaction catalyst, for example, platinum black, platinum chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and an alkene, bis(acetylacetic acid) platinum Platinum-based catalysts, palladium-based catalysts, rhodium-based catalysts and other platinum group metal catalysts. Furthermore, the amount of the addition reaction catalyst can be set as the amount of the catalyst, and it is generally preferable to prepare 0.5 to 1,000 ppm, especially 1 to 500, in terms of platinum group metals, relative to the component (A-1). about ppm.

The addition reaction control agent of the component (A-4) is not particularly limited as long as it has a curing reaction inhibitory effect on the addition reaction catalyst of the component (A-3), and conventionally known compounds can be used. Specific examples thereof include phosphorus-containing compounds such as triphenylphosphine; compounds containing nitrogen atoms such as tributylamine, tetramethylethylenediamine, and benzotriazole; compounds containing sulfur atoms; acetylene-based compounds such as acetylene alcohol Compounds; compounds containing two or more alkenyl groups; hydroperoxy compounds; maleic acid derivatives, etc. Since the degree of the hardening reaction inhibitory effect of the addition reaction control agent varies depending on its chemical structure, the amount of the addition reaction control agent is preferably adjusted to the optimum amount for each addition reaction control agent used. By blending the optimal amount of reaction control agent, the thermally conductive resin composition has excellent long-term storage stability and curability at room temperature.

[D] The wetting agent uses silanol group-containing silane and/or siloxane oligomers such as diphenyl silane diol and silanol group-terminated organosiloxane oligomers at both ends of the molecular chain. As the silicone oligomer, polysiloxane having an average degree of polymerization of 10 to 100 is preferred. In addition, relative to 100 parts by mass of (A-1) organopolysiloxane, the blending amount of the wetting agent is preferably 0 to 150 parts by mass, more preferably 5 to 130 parts by mass, and still more preferably Let it be the compounding quantity of the range of 10-100 mass parts.

[The thermal conductivity of the thermally conductive resin composition] The thermal conductivity of the thermally conductive resin composition is preferably 1.0 W/(m·K) or more, more preferably 1.2 W/(m·K) or more, and still more preferably 1.4 W/m·K or more. If the aforementioned thermal conductivity is 1.0 W/(m·K) or more, the heat generated from the heating element can be sufficiently transferred to the cooling part, which is preferable. In the present invention, the thermal conductivity is a value measured in accordance with ISO22007-2, and the device used is, for example, TPS-2500S manufactured by Kyoto Electronics Co., Ltd.

[Specific gravity of thermally conductive resin composition] The specific gravity of the thermally conductive resin composition is preferably 2.0 or less, more preferably 1.7 or less, and still more preferably 1.5 or less. If the aforementioned specific gravity is 2.0 or less, the effect of lowering the specific gravity is sufficient, and the cured product of the thermally conductive resin composition, that is, the cured thermally conductive resin, can be sufficiently reduced in weight, which is preferable. The specific gravity is a value measured in accordance with JIS K 6249.

[Heat conductive resin cured product] The present invention provides a cured thermally conductive resin, which is a cured product of the thermally conductive resin composition described above. The curing conditions are not particularly limited, but it is preferable to heat the thermally conductive resin composition in a temperature range of 100 to 300°C for 10 seconds to 1 hour.

[The thermal conductivity of the thermally conductive resin cured product] The thermal conductivity of the thermally conductive resin cured product is preferably 1.0 W/(m·K) or more, more preferably 1.2 W/(m·K) or more, and still more preferably 1.4 W/m·K or more. If the aforementioned thermal conductivity is 1.0 W/(m·K) or more, the heat generated from the heating element can be sufficiently transferred to the cooling part, which is preferable. The upper limit of the aforementioned thermal conductivity is not particularly limited, and it can be set to, for example, 3.0 W/(m·K). In the present invention, the thermal conductivity is a value measured in accordance with ISO22007-2, and the device used is, for example, TPS-2500S manufactured by Kyoto Electronics Co., Ltd.

[Specific gravity of thermally conductive resin cured product] The specific gravity of the thermally conductive resin cured product is preferably 2.0 or less, more preferably 1.7 or less, and still more preferably 1.5 or less. If the specific gravity is 2.0 or less, the effect of reducing the specific gravity is sufficient, and the weight reduction of the thermally conductive resin cured product can also be sufficiently achieved, which is preferable. The lower limit of the aforementioned specific gravity is not particularly limited, and can be set to, for example, 1.2. The specific gravity is a value measured in accordance with JIS K 6249.

[Hardness of thermally conductive resin cured material] The hardness of the thermally conductive resin cured product measured by an ASKER C hardness meter is preferably 60 or less, more preferably 40 or less and 1 or more. If the Asker C hardness of the thermally conductive resin cured product is 60 or less, it can adhere to the minute irregularities existing in the heat generating parts and the cooling parts, and the thermal resistance will not be too large, so the heat can be efficiently discharged, which is preferable.

[Thickness of thermally conductive resin cured product] The thickness of the thermally conductive resin cured product of the present invention is preferably 0.35 mm or more, and more preferably 0.75 mm or more. If the aforementioned thickness is 0.35 mm or more, the thermally conductive resin cured product can absorb the tolerances of components such as heat-generating parts and cooling parts, and can maintain adhesion. [Example]

Examples and comparative examples are listed below to more specifically illustrate the present invention, but the present invention is not limited by the following examples. The components (A) to (C) used in the following examples and comparative examples are as follows.

The thermosetting resin component (silicone resin component (A)) is composed of (A-1) to (A-7). (A-1) Component: an organopolysiloxane component represented by the following formula as the main polymer (dimethylpolysiloxane in which both ends have been blocked with dimethylvinylsilyl group, n= 190) 100 parts by mass;

(A-2) Component: 17 parts by mass of organohydrogenpolysiloxane (o=27, p=2) represented by the following formula as a crosslinking agent;

(A-3) Ingredient: 0.4 parts by mass of a 5 mass% chloroplatinic acid 2-ethylhexanol solution as a platinum-based hardening catalyst; (A-4) Component: 0.1 parts by mass of ethynylmethylene methanol as an addition reaction control agent;

(A-5) Component: 8 parts by mass of dimethyldiphenylpolysiloxane (j=8, k=4) represented by the following formula as a release agent;

(A-6) Component: 19 parts by mass of dimethylpolysiloxane having both ends blocked by trimethylsilyl groups represented by the following formula as a wetting agent;

(A-7) Component: 24 parts by mass of dimethylpolysiloxane having one end capped with trimethoxysilyl group represented by the following formula as a wetting agent;

(B) Ingredient: Boron Nitride (B-1) Agglomerated boron nitride: particle size distribution of 30 to 80 μm, average particle size of 60 μm, shape: scaly aggregate (B-2) Agglomerated boron nitride: particle size distribution of 30-60 μm, average particle size of 40 μm, shape: scaly aggregate

(C)Component: Thermally conductive filler (C-1) Aluminum hydroxide composed of the following (C-1-1): (C-1-2): (C-1-3) = 1:2:2 (mass ratio) (C-1-1) Aluminum hydroxide: The average particle size is 50 μm, and the shape is amorphous (C-1-2) Aluminum hydroxide: The average particle size is 8 μm, and the shape is amorphous (C-1-3) Aluminum hydroxide: The average particle size is 2 μm, and the shape is amorphous (C-2) Alumina composed of the following (C-2-1): (C-2-2): (C-2-3) = 1:2:4 (mass ratio) (C-2-1) Alumina: The average particle size is 20 μm, and the shape is amorphous (C-2-2) Alumina: The average particle size is 5 μm, and the shape is amorphous (C-2-3) Alumina: The average particle size is 1 μm, and the shape is amorphous (C-3) Zinc oxide: The average particle size is 0.5 μm, and the shape is amorphous (C-4) Silver: The average particle size is 10 μm, and the shape is amorphous

Using a planetary mixer, the components (A) to (C) were kneaded at the contents shown in Tables 1 and 2 for 60 minutes to obtain a thermally conductive resin composition (silicone composition). Then, various physical properties were evaluated in accordance with the following evaluation methods.

(Evaluation method) [Fluidity/Formability] Use a rheometer (HAAKE RheoStress 6000) to measure the thermally conductive resin composition (silicon oxide composition) at 25°C to determine whether the shear viscosity is 10 s ^-1 Below, the fluidity is evaluated based on whether the viscosity is 75 Pa·s or less.

Flow the thermally conductive silicon-oxygen composition into a 6 mm thick mold and degas it for 1 hour, then heat and harden it at 110°C for 10 minutes to obtain a thermally conductive low-density sheet, and then determine whether the thermally conductive low-density sheet has developed The foam is used as a benchmark to evaluate the formability. When the fluidity and formability meet the criteria, it is evaluated as ○, and when any one or all of the fluidity and formability are not satisfied, it is evaluated as ×.

[proportion] After the thermally conductive silica composition was poured into a 2 mm thick mold, it was heat-cured at 110°C for 10 minutes to obtain a thermally conductive low specific gravity sheet, and then the specific gravity of the thermally conductive low specific gravity sheet was measured by the water displacement method.

[Thermal conductivity/ASKER C hardness] After sandwiching the obtained thermally conductive silicone composition in a Teflon (registered trademark) sheet, it was heated and cured at 110°C for 10 minutes. TPS-2500S was used to measure the thermal conductivity of the obtained thermally conductive silicone cured product, and the ASKER C hardness tester was used to measure the ASKER C hardness of the obtained thermally conductive silicone cured product.

(Examples 1 to 5, Comparative Examples 1 to 6) The results of Examples 1 to 5 and Comparative Examples 1 to 6 are shown in Tables 1 and 2. [Table 1]

[Table 2]

In Example 1, agglomerated boron nitride with an average particle diameter of 60 μm was used as the boron nitride, and in Examples 2 to 5, agglomerated boron nitride with an average particle diameter of 40 μm was used. In Examples 1 to 3, aluminum hydroxide was used as the thermally conductive filler, in Example 4, aluminum oxide was used as the thermally conductive filler, and in Example 5, zinc oxide was used as the thermally conductive filler. As in Examples 1 to 5, by blending boron nitride and thermally conductive fillers into the resin composition (silicone resin component), it is possible to stably obtain a low specific gravity and high thermal conductivity resin composition (silicone resin composition) And its hardened material.

In Comparative Example 1, it was blended so that the silicone resin component was 90% by volume and the boron nitride was 10% by volume. Although the specific gravity of the thermally conductive low specific gravity sheet is suppressed to 1.10 and is very low, the thermal conductivity of the thermally conductive silicone cured product is 0.58 W/(m·K), and its thermal conductivity is insufficient. In Comparative Example 2, it was blended so that the silicone resin component was 75% by volume and the boron nitride was 25% by volume. The blended silicone resin composition is not in a paste form, but becomes a solid state in which the silicone resin component and boron nitride have been separated, and a sheet with stable thermal conductivity cannot be produced. Furthermore, the one-time thermal conductivity shows 2.05 W/(m·K).

In Comparative Example 3, it was blended so that the silicone resin component was 54% by volume and the thermally conductive filler aluminum hydroxide was 46% by volume. Although the specific gravity of the thermally conductive low specific gravity sheet is suppressed to 1.61 and low, the thermal conductivity of the silicone cured product is 0.89 W/(m·K), and its thermal conductivity is insufficient.

In Comparative Example 4, it was blended so that the silicone resin component was 65% by volume, boron nitride was 25% by volume, and aluminum hydroxide as a thermally conductive filler was 10% by volume. As in Comparative Example 2, it became a solid composition in which the silicone resin component and boron nitride were separated, and a sheet with stable thermal conductivity could not be produced. Furthermore, the one-time thermal conductivity shows 3.92 W/(m·K). If there is too much boron nitride like this, although a resin composition with high thermal conductivity can be obtained, it is difficult to make the resin composition into a paste form, and the objective of obtaining a resin composition with stable physical properties and a cured product thereof cannot be achieved.

In Comparative Example 5, the silicone resin component was 40% by volume, boron nitride was 10% by volume, and aluminum hydroxide as the thermally conductive filler was 50% by volume. As in Comparative Example 2 and Comparative Example 4, it became a solid resin composition in which the silicone resin component and boron nitride were separated, and a sheet with stable thermal conductivity could not be produced. Furthermore, the one-time thermal conductivity shows 2.72 W/(m·K). Even if there are too many thermally conductive fillers in this way, it is difficult to make the resin composition into a paste form.

In Comparative Example 6, the composition was prepared so that the silicone resin component was 82% by volume, the boron nitride was 10% by volume, and the silver as the thermally conductive filler was 8% by volume. Although the specific gravity of the thermally conductive low specific gravity sheet is suppressed to 1.84, the thermal conductivity of the silicone cured product is 0.82 W/(m·K) and the thermal conductivity is insufficient. When the specific gravity of the thermally conductive resin composition is lowered in this way, it is necessary to reduce the blending amount of a thermally conductive filler with a heavier specific gravity such as silver. However, the filling rate of the thermally conductive filler with respect to the resin is lowered, and therefore the thermal conductivity is greatly reduced.

From the foregoing, it can be seen that a predetermined amount of boron nitride and a thermally conductive filler other than boron nitride is blended into the thermosetting resin component to obtain a low specific gravity thermally conductive resin composition. The low specific gravity thermally conductive resin composition has good moldability. It can also contribute to the weight reduction of heat dissipation components such as mobile devices and automobiles.

In addition, the present invention is not limited to the above-mentioned embodiment. The above-mentioned embodiments are only examples, and as long as they have substantially the same configuration and produce the same effects as the technical ideas described in the scope of the patent application of the present invention, whatever they are, they are included in the technical scope of the present invention.

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Claims (12)

A thermally conductive resin composition, characterized in that it contains: 50 to 80% by volume of thermosetting resin components, 5 to 20% by volume of boron nitride, and 10 to 45% by volume of thermally conductive fillers other than boron nitride. The thermally conductive resin composition according to claim 1, wherein the boron nitride is a secondary particle, and the secondary particle is formed by aggregating primary particles of scaly boron nitride into a radial shape. The thermally conductive resin composition according to claim 1, wherein the specific gravity of the thermally conductive filler is 2.0 to 6.0. The thermally conductive resin composition according to claim 2, wherein the thermally conductive filler has a specific gravity of 2.0 to 6.0. A cured thermally conductive resin characterized by being a cured thermally conductive resin composition according to any one of claims 1 to 4. The thermally conductive resin cured product described in claim 5 has a thermal conductivity of 1.0 W/(m·K) or more. The thermally conductive resin cured product according to claim 5 has a specific gravity of 2.0 or less. The thermally conductive resin cured product according to claim 6 has a specific gravity of 2.0 or less. The thermally conductive resin cured product according to claim 5 has a hardness measured by an ASKER C hardness tester of 60 or less. The thermally conductive resin cured product according to claim 6 has a hardness measured by an ASKER C hardness tester of 60 or less. The thermally conductive resin cured product according to claim 7 has a hardness measured by an ASKER C hardness tester of 60 or less. The thermally conductive resin cured product according to claim 8 has a hardness measured by an ASKER C hardness tester of 60 or less.