JP2020176201A - Heat-conductive resin composition and heat-conductive resin cured product - Google Patents

Abstract

To stably provide a high heat-conductive resin composition and a high heat-conductive resin cured product which have high heat conductivity, have small specific gravity and are effective as a heat dissipating material.SOLUTION: A heat-conductive resin composition contains 50-80 vol.% of a thermosetting resin component, 5-20 vol.% of boron nitride, and 10-45 vol.% of a heat-conductive filler other than the boron nitride. The preferable boron nitride is second particles in which primary particles of scaly boron nitrite are radially aggregated. The preferable specific gravity of the heat-conductive filler is 2.0-6.0. A heat-conductive resin cured product is a cured product of the heat-conductive resin composition.SELECTED DRAWING: None

Description

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

The heat generation density of CPUs, driver ICs, memory, and other electronic components used in electronic devices such as personal computers and mobile phones is rapidly increasing as they become smaller and more integrated. When heat is accumulated in an electronic component, the temperature of the electronic component rises, which may cause malfunction or failure. In order to efficiently dissipate heat generated from electronic components to a cooling member such as a heat sink, a method of using a heat radiating member having high thermal conductivity has been proposed.

In recent years, there has been an increasing demand for heat radiating members for in-vehicle lithium-ion batteries. Specific places of use are the interface between the battery cell and the cell housing and the interface between the battery module and the battery housing. If an excessive load is applied to the battery cell or the like, it may cause malfunction, so the heat radiating member is required to have flexibility. Further, in in-vehicle applications, long-term reliability is required up to a temperature of around −40 ° C., which is the minimum temperature in cold regions, and a high temperature of 150 ° C. or higher of the heat generating member. Further, characteristics such as flame retardancy and electrical insulation are often required. Silicone is suitable as a material that satisfies all of these characteristics, and a thermally conductive silicone composition containing silicone and a thermally conductive filler or a cured product thereof is often used as a heat radiating member.

As the fuel efficiency regulations of automobiles are tightened all over the world, efforts are being made to improve fuel efficiency by reducing the size and output of engines and reducing air resistance. Further, since the fuel consumption becomes worse as the weight of the automobile becomes heavier, it is also desired to reduce the weight of the mounted parts. In particular, in hybrid vehicles and electric vehicles, the scale of lithium-ion batteries used is large, and further weight reduction is required for the vehicle body. Further, since the amount of the heat radiating member used for heat dissipation of the lithium ion battery is very large, it is desired to reduce the weight of the heat radiating member.

However, in general, the heat radiating member has a large specific gravity. In particular, the conventional composition having a high thermal conductivity has a large amount of the heat conductive filler and a large specific gravity of the composition. Therefore, the weight of the heat radiating member becomes large, the total weight of the vehicle body also becomes large, and the fuel consumption increases. Therefore, there is a demand for a technique for reducing the specific gravity of the heat radiating member.

One method is to use a filler having a low specific gravity and high thermal conductivity. As described in Patent Document 1 and Patent Document 2, a thermally conductive sheet in which aggregated secondary particles of boron nitride are dispersed in a resin to improve thermal conductivity has been developed. However, the filling rate of boron nitride is high, and the specific gravity of the composition is large. Further, Patent Document 2 describes a method of combining agglomerated particles of boron nitride and aluminum oxide. 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 of reducing the specific gravity of the resin by adding hollow particles having a small specific gravity to the resin is shown. However, many of the hollow particles have low pressure resistance, and it is difficult to reduce the specific gravity of the resin because the hollow particles burst by a manufacturing method in which the resin is pumped.

As described above, the conventional composition having a high thermal conductivity has a large amount of the heat conductive filler, so that the specific gravity of the composition is large. Further, when a material having a low pressure resistance such as hollow particles was used in an attempt to reduce the specific gravity, a resin composition having a desired specific gravity could not be obtained.

JP-A-2010-157563 Japanese Unexamined Patent Publication No. 2011-144234 Japanese Unexamined Patent Publication No. 2012-119674

The present invention has been made in view of the above circumstances, and stably provides 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-dissipating material. The purpose is to do.

In order to achieve the above problems, in the present invention, heat 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 a thermally conductive filler other than the boron nitride. Provided is a conductive resin composition.

Such a thermally conductive resin composition is a highly thermally conductive resin composition having high thermal conductivity and low specific gravity.

The boron nitride is preferably secondary particles in which scaly boron nitride primary particles are radially aggregated.

Flaky boron nitride has a layered crystal structure and exhibits anisotropic thermal conductivity due to a significant difference in thermal conductivity between the plane direction and the stacking direction of the crystal. On the other hand, since the secondary particles in which the primary particles of scaly boron nitride are radially aggregated have isotropic thermal conductivity, stable heat is stable regardless of the molding method or usage form when the thermally conductive resin composition is used. Shows conductivity.

The specific gravity of the thermally conductive filler is preferably 2.0 to 6.0.
When the specific gravity of the heat conductive filler is 2.0 to 6.0, the specific gravity of the heat conductive resin composition becomes smaller.

The present invention provides a cured product of a thermosetting resin, which is a cured product of the above-mentioned thermosetting resin composition.
This thermosetting resin cured product is a highly thermally conductive resin cured product having high thermal conductivity and low specific gravity, which is effective as a heat radiating material.

The thermal conductivity of this cured thermosetting resin is preferably 1.0 W / (m · K) or more.
Such a thermal conductivity is preferable because the heat from the heating element can be sufficiently transferred to the cooling portion.

Further, the specific gravity of the cured thermosetting resin is preferably 2.0 or less.
Such a specific gravity is preferable because the effect of lowering the specific gravity is sufficiently obtained.

The hardness of the cured thermosetting resin of the present invention measured by an Asker C hardness tester is preferably 60 or less.
Such hardness of the cured product is preferable because it can adhere to micro-concavities and convexities existing in heat-generating parts and cooling parts, the thermal resistance does not become too large, and heat can be efficiently discharged. ..

Since both the heat conductive resin composition and the thermosetting resin cured product of the present invention achieve both high heat conductivity and low specific gravity, the high heat conductive resin composition and the high heat conductive resin effective as a heat radiating material. It becomes a cured product.

Further, the thermosetting resin composition and the cured thermosetting resin have a large amount of thermosetting resin component as a base material of 50 to 80% by volume, and the filling rate of the thermally conductive filler other than boron nitride and boron nitride is increased. By limiting the flow, the flowability and processability of the resin composition are improved, and a thermosetting resin composition and a thermosetting resin cured product showing stable thermal conductivity regardless of the molding method and usage mode are provided. To do.

As described above, there has been a demand for the development of a highly thermally conductive resin composition and a cured highly thermally conductive resin, which have high thermal conductivity and low specific gravity and are effective as heat-dissipating materials.

As a result of diligent studies to achieve the above object, the present inventors have made 50 to 80% by volume of a thermosetting resin component as a base material, 5 to 20% by volume of boron nitride, and thermal conductivity other than boron nitride. It has been found that a resin composition containing 10 to 45% by volume of a filler and a cured product thereof become a high thermosetting resin composition having a small specific gravity and a cured product thereof, and are suitable as a heat radiating member. Further, for the boron nitride, select secondary particles in which primary particles of scaly boron nitride are radially aggregated, and for the thermally conductive filler, select an inorganic filler having a specific gravity of 2.0 to 6.0. By blending, it was found that the specific gravity of the highly thermally conductive resin composition and the cured product thereof was smaller and the thermal conductivity was higher, and the preferred embodiment of the present invention was completed.

That is, the present invention is a heat 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 a heat conductive filler other than the boron nitride. is there.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.
Thermal Conductive Resin Composition [Boron Nitride]
The boron nitride contained in the thermally conductive resin composition of the present invention is preferably secondary particles in which primary particles of scaly boron nitride are radially aggregated. Since particles having such a form have isotropic thermal conductivity, stable thermal conductivity is exhibited regardless of the molding method or usage form when the thermally conductive resin composition is used.

The secondary particle size of boron nitride is not particularly limited, but is preferably 10 to 200 μm. Boron nitride having such a secondary particle size is easily dispersed in the resin and easily mixed. Further, in the case of producing a heat conductive sheet, if the aggregated secondary particles of boron nitride are too large, the tack on the surface is impaired, the adhesion to the base material is deteriorated, and heat cannot be efficiently discharged. Therefore, the aggregated secondary particles of boron nitride are preferably 80% or less of the thickness of the heat conductive resin layer.

In the present invention, in order to increase the thermal conductivity in the resin composition, it is necessary to contain 5 to 20% by volume of boron nitride, preferably 5 to 15% by volume. If the amount of boron nitride is less than 5% by volume, the thermal conductivity of the thermally conductive resin composition and the cured product of the thermally conductive resin becomes insufficient. On the other hand, when boron nitride exceeds 20% by volume, the flowability and moldability of the thermally conductive resin composition are lowered.

[Thermal conductive filler other than boron nitride]
As the heat conductive filler other than boron nitride contained in the heat conductive resin composition of the present invention, inorganic particles having a specific gravity of 2.0 to 6.0 are preferable. 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, artificial diamond, silicon carbide and the like can be used. In particular, aluminum hydroxide and aluminum oxide are suitable as the heat conductive filler because they have a light specific gravity and are excellent in filling property into a resin. These thermally conductive fillers may be used alone or in combination of two or more.

In the present invention, among these, aluminum hydroxide or aluminum oxide having a particularly light specific gravity and excellent filling property into a resin is preferable.

In the present invention, in order to increase the thermal conductivity in the resin composition, it is necessary to contain the thermally conductive filler in an amount of 10 to 45% by volume, preferably 10 to 25% by volume. If the amount of the heat conductive filler is less than 10% by volume, the heat conductivity of the heat conductive resin composition and the cured product of the heat conductive resin becomes insufficient. Further, when the heat conductive filler exceeds 45% by volume, the specific gravity of the heat conductive resin composition and the thermosetting resin cured product increases. In addition, the flowability and moldability of the thermally conductive resin composition are reduced.

[Thermosetting resin component]
The thermosetting resin used as the base material of the heat conductive resin composition of the present invention is not particularly limited, and for example, silicone resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, polyurethane. A resin, a polyimide resin, or the like can be used. Silicone resin is particularly suitable because it has a simple curing method. The thermosetting resin component of the present invention can contain general raw materials for thermosetting resins such as raw materials for these resins before curing, curing agents, and catalysts.

The thermosetting resin composition of the present invention contains 50 to 80% by volume of a thermosetting resin component. When the thermosetting resin component is less than 50% by volume, the flowability and moldability of the thermosetting resin composition are lowered. If the thermosetting resin component exceeds 80% by volume, the thermal conductivity of the thermosetting resin composition and the cured thermosetting resin becomes insufficient.
The silicone resin component will be described in detail below, but the present invention is not limited thereto.

[Organopolysiloxane component]
The organopolysiloxane component used as a base material is not particularly limited, and examples thereof include a component used as a base material of the silicone composition. For example, it is an organopolysiloxane used as a main polymer of an addition-curable silicone composition, and in particular, an organopolysiloxane having at least two alkenyl groups in one molecule (A-1) is preferable. Examples of the component (A-1) include organopolysiloxane having a structure represented by the following general formula (1) and having at least two alkenyl groups in one molecule.

R ¹ _a SiO _{(4-a) / 2} (1)
(In the formula, R ¹ represents a monovalent hydrocarbon group having 1 to 18 substituted or unsubstituted carbon atoms, preferably 1 to 8 independently, and a is 1.90 to 2.05.)

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

Examples of R ¹ include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and an octadecyl group; a cyclopentyl group and a cyclohexyl group. Cycloalkyl groups such as phenyl group, trill group, aryl group such as xylyl group and naphthyl group; aralkyl group such as benzyl group, phenethyl group and 3-phenylpropyl group; 3,3,3-trifluoropropyl group and 3 -Alkyl halide groups such as chloropropyl group; alkenyl groups such as vinyl group, allyl group, butenyl group, pentenyl group and hexenyl group can be mentioned.

When the organopolysiloxane component serving as the base material is an organopolysiloxane having at least two alkenyl groups in one molecule of (A-1), the thermally conductive silicone composition of the present invention further comprises the following (A-1). A-2) Organohydrogenpolysiloxane having at least two or more hydrogen atoms directly bonded to silicon atoms, (A-3) platinum-based curing catalyst, and (A-4) addition reaction control agent can be included.

Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to the silicon atom of the component (A-2) reacts with the component (A-1) and acts as a cross-linking agent, and its molecular structure There is no particular limitation on the above, and various conventionally manufactured ones such as linear, annular, branched, and three-dimensional network structures (resin-like) can be used, but two or more, preferably 3 in one molecule. It is necessary to have hydrogen atoms (hydrosilyl groups represented by Si—H) bonded to one or more silicon atoms, and usually 2 to 300, preferably 3 to 200, more preferably about 4 to 100. It is desirable to have a Si—H group.

The blending amount of the component (A-2) is such that the number of moles of the hydrogen atom directly bonded to the silicon atom is 0.1 to 5.0 times the number of moles of the alkenyl group derived from the component (A-1). It is preferable to do so.

As such a component (A-2), those represented by the following general formula (2) are preferable.
R ² _b H _c SiO _{(4-bc) / 2} (2)
The R ² is an unsubstituted monovalent hydrocarbon group bonded to a silicon atom having 1 to 10 carbon atoms, excluding an aliphatic unsaturated bond such as an alkenyl group, and is an unsubstituted monovalent group in this R ² . Examples of the hydrocarbon group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group and decyl. Examples thereof include an alkyl group such as an alkyl group, a phenyl group, a trill group, an aryl group such as a xsilyl group and a naphthyl group, and an aralkyl group such as a benzyl group, a phenylethyl group and a phenylpropyl group. The unsubstituted monovalent hydrocarbon group R ^2, preferably an alkyl group, an aryl group, especially a methyl group, it is desirable from the viewpoint of the flame retardancy phenyl. Further, 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 1.0. 2.0 and c are 0.01 to 1.0, and b + c is 1.5 to 2.5.

The platinum-based curing catalyst of the component (A-3) is a catalyst for promoting the hydrosilylation addition reaction between the alkenyl group in the component (A-1) and the Si—H group in the component (A-2). .. Examples of this addition reaction catalyst include platinum black, second platinum chloride, platinum chloride acid, a reaction product of platinum chloride acid and monovalent alcohol, a complex of platinum chloride acid and olefins, and a platinum-based catalyst such as platinum bisacetoacetate. , Platinum group metal catalysts such as palladium catalysts and rhodium catalysts. The blending amount of this addition reaction catalyst can be a catalytic amount, but usually, as a platinum group metal, 0.5 to 1,000 ppm, particularly about 1 to 500 ppm, is blended with respect to the component (A-1). Is preferable.

The addition reaction control agent for the component (A-4) is not particularly limited as long as it is a compound having a curing reaction inhibitory effect on the addition reaction catalyst for the component (A-3), and conventionally known ones should be used. Can be done. 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 compounds such as acetylene alcohols; alkenyl. Examples thereof include compounds containing two or more groups; hydroperoxy compounds; maleic acid derivatives and the like. The amount of the addition reaction control agent to be blended is preferably adjusted to the optimum amount for each addition reaction control agent to be used because the degree of the curing reaction suppressing action of the addition reaction control agent differs depending on its chemical structure. By blending the optimum amount of the reaction control agent, the thermally conductive resin composition becomes excellent in long-term storage stability and curability at room temperature.

[Wetter]
As the wetter, silanol group-containing silanes such as diphenylsilanediol and silanol group-blocking organosiloxane oligomers at both ends of the molecular chain and / or siloxane oligomers are used. As the siloxane oligomer, polysiloxane having an average degree of polymerization of 10 to 100 is preferable. The amount of the wetter to be blended is preferably 0 to 150 parts by mass, more preferably 5 to 130 parts by mass, and further preferably 10 to 100 parts by mass with respect to 100 parts by mass of (A-1) organopolysiloxane. The blending amount can be in the range of parts.

[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 further preferably 1.4 W / mK. That is all. When the thermal conductivity is 1.0 W / (m · K) or more, the heat from the heating element can be sufficiently transferred to the cooling portion, which is preferable. In the present invention, the thermal conductivity is a value measured in accordance with ISO22007-2, and the apparatus used is, for example, TPS-2500S manufactured by Kyoto Electronics.

[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 further preferably 1.5 or less. When the specific gravity is 2.0 or less, the effect of lowering the specific gravity is sufficient, and the weight reduction of the cured product of the thermosetting resin, which is the cured product of the thermosetting resin composition, is sufficiently achieved, which is preferable. The specific gravity is a value measured in accordance with JIS K 6249.

Thermosetting Resin Cured Product The present invention provides a thermosetting resin cured product which is a cured product of the above-mentioned thermosetting resin composition. The curing conditions are not particularly limited, but it is preferable that the heat conductive resin composition is heated in a temperature range of 100 to 300 ° C. for 10 seconds to 1 hour.

[Thermal conductivity of cured resin]
Thermal conductivity The thermal conductivity of the cured resin is preferably 1.0 W / (m · K) or more, more preferably 1.2 W / (m · K) or more, and even more preferably 1.4 W / mK. That is all. When the thermal conductivity is 1.0 W / (m · K) or more, the heat from the heating element can be sufficiently transferred to the cooling portion, which is preferable. In the present invention, the thermal conductivity is a value measured in accordance with ISO22007-2, and the apparatus used is, for example, TPS-2500S manufactured by Kyoto Electronics.

[Specific gravity of thermosetting resin cured product]
The specific gravity of the cured thermosetting resin is preferably 2.0 or less, more preferably 1.7 or less, and further preferably 1.5 or less. When the specific gravity is 2.0 or less, the effect of lowering the specific gravity is sufficient, and the weight reduction of the cured thermosetting resin is sufficiently achieved, which is preferable. The specific gravity is a value measured in accordance with JIS K 6249.

[Hardness of thermosetting resin cured product]
The hardness of the cured thermosetting resin as measured by the Asuka-C hardness tester is preferably 60 or less, more preferably 40 or less and 1 or more. If the hardness of the thermosetting resin cured product is Asuka-C60 or less, it can adhere to the micro unevenness existing in the heat generating part and the cooling part, the thermal resistance does not become too large, and the heat is efficiently discharged. It is preferable because it can be used.

[Thickness of thermosetting resin cured product]
The thickness of the cured product of the thermosetting resin of the present invention is preferably 0.35 mm or more, more preferably 0.75 mm or more. When the thickness is 0.35 mm or more, the thermosetting resin cured product can absorb the tolerance of members such as heat-generating parts and cooling parts, and the adhesion can be maintained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
The components (A) to (C) used in the following Examples and Comparative Examples are shown below.

The silicone resin component (A) is composed of (A-1) to (A-7).
Component (A-1): 100 parts by mass of an organopolysiloxane component (dimethylpolysiloxane with both ends sealed with a dimethylvinyl group, n = 190) represented by the following formula, which is the main polymer.

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

(A-3) Component: 0.4 parts by mass of a 5 mass% 2-ethylhexanol chloride solution as a platinum-based curing catalyst,
(A-4) Ingredients: 0.1 part by mass of ethynylmethyldencarbinol as an addition reaction regulator

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

Component (A-6): 19 parts by mass of dimethylpolysiloxane, which was sealed at both ends with a trimethyl group represented by the following formula as a wetter.

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

(B) Component: Boron Nitride (B-1) Aggregated Boron Nitride: Particle Size Distribution 30-80 μm, Average Particle Size 60 μm, Shape: Scale-like Aggregate (B-2) Aggregate Boron Nitride: Particle Size Distribution 30-60 μm, Average Particle size 40 μm, shape: scaly aggregate

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

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

(Evaluation methods)
[Flowability / Moldability]
The thermally conductive silicone composition was measured at 25 ° C. using a rheometer (HAAKE RheoStress 6000), and the flowability was evaluated based on whether the shear viscosity was 10 s ^-1 or less and the viscosity was 75 Pa · s or less.

The heat conductive silicone composition was poured into a 6 mm thick mold, defoamed for 1 hour, and then heat-cured at 110 ° C. for 10 minutes. The moldability was evaluated based on whether or not there was foaming in the heat conductive low specific gravity sheet. did.
The case where the flowability and moldability met the criteria was evaluated as ◯, and the case where either one or both of the flowability and moldability were not satisfied was evaluated as x.

[specific gravity]
The heat conductive silicone composition was poured into a mold having a thickness of 2 mm and heat-cured at 110 ° C. for 10 minutes, and the specific gravity of the obtained heat conductive low specific gravity sheet was measured by an underwater substitution method.

[Thermal conductivity / Asker C hardness]
The obtained thermally conductive silicone composition was sandwiched between Teflon (registered trademark) sheets and heat-cured at 110 ° C./10 minutes. The thermal conductivity of the obtained thermally conductive silicone cured product was measured with TPS-2500S, and the Asker C hardness was measured with an Asker C hardness tester.

(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.

As the boron nitride, agglutinated boron nitride having an average particle size of 60 μm was used in Example 1, and agglutinated boron nitride having an average particle size of 40 μm was used in Examples 2 to 5. As the heat conductive filler, aluminum hydroxide was used in Examples 1 to 3, aluminum oxide was used in Example 4, and zinc oxide was used in Example 5. By blending boron nitride and a heat conductive filler with the silicone resin component as in Examples 1 to 5, a silicone resin composition having a low specific gravity and high heat conductivity and a cured product thereof can be stably obtained.

In Comparative Example 1, the silicone resin component was blended in an amount of 90% by volume and boron nitride in a proportion of 10% by volume. The specific gravity of the heat conductive low specific gravity sheet is suppressed to very low at 1.10, but the thermal conductivity of the cured heat conductive silicone is 0.58 W / (m · K), which is insufficient. In Comparative Example 2, the silicone resin component was blended in an amount of 75% by volume and the boron nitride content was blended in an amount of 25% by volume. After blending, the silicone resin composition was not in the form of a paste, but in the form of a solid in which the silicone resin component and boron nitride were separated, and it was not possible to prepare a sheet having stable thermal conductivity. The one-time thermal conductivity was 2.05 W / (m · K).

In Comparative Example 3, the silicone resin component was blended in an amount of 54% by volume, and aluminum hydroxide as a heat conductive filler was blended in an amount of 46% by volume. Thermal conductivity The specific gravity of the low specific gravity sheet is suppressed to as low as 1.61, but the thermal conductivity of the cured silicone product is 0.89 W / (m · K), which is insufficient thermal conductivity.

In Comparative Example 4, the silicone resin component was blended in an amount of 65% by volume, boron nitride in an amount of 25% by volume, and aluminum hydroxide as a thermally conductive filler in an amount of 10% by volume. Similar to Comparative Example 2, the silicone resin component and boron nitride were separated into a solid composition, and a sheet having stable thermal conductivity could not be produced. The one-time thermal conductivity was 3.92 W / (m · K). If the amount of boron nitride is too large as described above, a resin composition having high thermal conductivity can be obtained, but it is difficult to make the resin composition into a paste, and a resin composition having stable physical properties and a cured product thereof can be obtained. The purpose cannot be achieved.

In Comparative Example 5, the silicone resin component was blended in an amount of 40% by volume, boron nitride in 10% by volume, and aluminum hydroxide as a heat conductive filler in an amount of 50% by volume. Similar to Comparative Example 2 and Comparative Example 4, the silicone resin component and boron nitride were separated into a solid resin composition, and a sheet having stable thermal conductivity could not be produced. The one-time thermal conductivity was 2.72 W / (m · K). Even if the amount of the thermally conductive filler is too large as described above, it becomes difficult to make the resin composition into a paste.

In Comparative Example 6, the silicone resin component was blended in an amount of 82% by volume, boron nitride in 10% by volume, and silver as a thermally conductive filler in an amount of 7% by volume. Thermal conductivity The specific gravity of the low specific gravity sheet is 1.84, but the thermal conductivity of the cured silicone product is 0.82 W / (m · K), which means that the thermal conductivity is insufficient. When trying to reduce the specific gravity of the heat conductive resin composition in this way, it is necessary to reduce the amount of the heat conductive filler having a heavy specific gravity such as silver, but the filling ratio of the heat conductive filler to the resin is high. It will be lowered and the thermal conductivity will be greatly reduced.

As described above, the low specific gravity heat conductive resin composition obtained by blending a predetermined amount of boron nitride and a heat conductive filler other than boron nitride with the thermosetting resin component has good moldability and is a mobile device. It was found that it can also contribute to the weight reduction of heat dissipation members such as automobiles and automobiles.

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. Is included in the technical scope of.

In Comparative Example 6, the silicone resin component was blended in an amount of 82% by volume, boron nitride in 10% by volume, and silver as a thermally conductive filler in an amount of 8 % by volume. Thermal conductivity The specific gravity of the low specific gravity sheet is 1.84, but the thermal conductivity of the cured silicone product is 0.82 W / (m · K), which means that the thermal conductivity is insufficient. When trying to reduce the specific gravity of the heat conductive resin composition in this way, it is necessary to reduce the amount of the heat conductive filler having a heavy specific gravity such as silver, but the filling ratio of the heat conductive filler to the resin is high. It will be lowered and the thermal conductivity will be greatly reduced.

Claims (7)

A thermosetting 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 a thermally conductive filler other than the boron nitride. Stuff. The thermally conductive resin composition according to claim 1, wherein the boron nitride is a secondary particle in which primary particles of scaly boron nitride are radially aggregated. The heat conductive resin composition according to claim 1 or 2, wherein the heat conductive filler has a specific gravity of 2.0 to 6.0. A cured product of a thermosetting resin, which is a cured product of the thermosetting resin composition according to any one of claims 1 to 3. The cured product of a thermosetting resin according to claim 4, wherein the thermal conductivity is 1.0 W / (m · K) or more. The thermosetting resin cured product according to claim 4 or 5, wherein the specific gravity is 2.0 or less. The thermosetting resin cured product according to any one of claims 4 to 6, wherein the hardness measured by an Asker C hardness tester is 60 or less.