JP2023078170A - Heat-conductive resin composition, cured product, and method of heat release - Google Patents

Abstract

The present invention provides a thermally conductive resin composition which is excellent in low-temperature curability and handleability and capable of forming a cured product excellent in thermal conductivity. A thermally conductive resin composition containing the following components (A) to (C): (A) an epoxy resin, (B) an adduct-type latent curing agent that is solid at 25° C., (C) the following ( It is a mixture of components C1) to (C3), the mass ratio of component (C1) to component (C3) is 0.14 to 1.0, and the mass ratio of component (C2) to component (C3) is 0. (C1) Thermally conductive powder having an average particle size of 0.01 μm or more and less than 2 μm, (C2) Thermally conductive powder having an average particle size of 2 μm or more and less than 20 μm, (C3) Thermally conductive powder having an average particle size of 20 μm or more and less than 150 μm. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a thermally conductive resin composition, a cured product obtained by curing the composition, and a heat dissipation method for electric and electronic parts using the composition.

2. Description of the Related Art In recent years, a thermally conductive resin has been used between a heating element of an electrical/electronic component and a heat radiation member such as a radiation fin for the purpose of dissipating heat generated from the electrical/electronic component such as a semiconductor to the outside. As the thermally conductive resin, an epoxy resin-based thermally conductive resin is often used because it can achieve both adhesiveness and thermal conductivity. Since conventional epoxy resin-based thermally conductive resins use dicyandiamide, hydrazide, or the like as a curing agent, they need to be heated to over 150° C. for curing.

The use of plastic materials is increasing due to the demand for weight reduction of electric and electronic parts, but it is known that plastic materials are vulnerable to high temperatures. Therefore, epoxy resin-based thermally conductive resins are required to have low-temperature curability (specifically, curability at 150° C. or less).

Against this background, Japanese Patent Application Laid-Open No. 2009-292881 (corresponding to US Patent Application Publication No. 2009/298965) discloses a low-temperature curable resin containing an amine adduct-based latent curing agent and a high thermal conductivity filler. Disclosed is a highly thermally conductive epoxy resin-based composition having excellent thermal conductivity.

However, the thermal conductivity of the cured epoxy resin composition disclosed in the experimental example of Japanese Patent Application Laid-Open No. 2009-292881 (corresponding to US Patent Application Publication No. 2009/298965) is 2.3 W/m.・K, and its thermal conductivity was not satisfactory. In addition, the epoxy resin compositions disclosed in the experimental examples of the above publications contain a large amount of aluminum oxide for the purpose of imparting thermal conductivity, and therefore have a problem of high viscosity and poor handleability. .

Accordingly, an object of the present invention is to provide a thermally conductive resin composition which is excellent in low-temperature curability (curability at 150° C. or less) and handleability, and which can form a cured product having excellent thermal conductivity. .

The present invention includes the following embodiments.
[1] A thermally conductive resin composition containing the following components (A) to (C):
(A) Epoxy resin (B) Adduct-type latent curing agent that is solid at 25 ° C. (C) A mixture of (C1) to (C3) below, wherein the mass ratio of (C1) to (C3) ((C1) /(C3)) is from 0.14 to 1.0 and the mass ratio of (C2) to (C3) ((C2)/(C3)) is from 0.25 to 1.5;
(C1) Thermally conductive powder with an average particle size of 0.01 μm or more and less than 2 μm (C2) Thermally conductive powder with an average particle size of 2 μm or more and less than 20 μm (C3) Thermally conductive powder with an average particle size of 20 μm or more and less than 150 μm .
[2] The components (C1) to (C3) are each independently at least one thermally conductive powder selected from the group consisting of alumina, zinc oxide, aluminum nitride, boron nitride, carbon and diamond. The thermally conductive resin composition according to [1].
[3] The thermally conductive resin composition according to [1] or [2], wherein the components (C1) to (C3) are spherical or amorphous.
[4] The thermally conductive resin composition according to any one of [1] to [3], wherein the component (C) is a mixture containing spherical thermally conductive powder and amorphous thermally conductive powder. .
[5] In the total 100% by mass of (C1), (C2) and (C3), the component (C1) is 5 to 60% by mass, the component (C2) is 10 to 65% by mass, and the component (C3) is The thermally conductive resin composition according to any one of [1] to [4], containing 30 to 85% by mass.
[6] The thermally conductive resin composition according to any one of [1] to [5], wherein the content of component (C) in the thermally conductive resin composition is 55 to 99% by mass.
[7] The thermally conductive resin composition according to any one of [1] to [6], wherein the component (A) is liquid at 25°C.
[8] The thermally conductive resin composition according to any one of [1] to [7], containing 5 to 50 parts by mass of component (B) with respect to 100 parts by mass of component (A).
[9] The thermally conductive resin composition according to any one of [1] to [8], which is liquid at 25°C.
[10] The thermally conductive resin composition according to any one of [1] to [9], wherein the component (B) has an average particle size of 0.1 to 100 μm.
[11] The thermally conductive resin composition according to any one of [1] to [10], wherein the component (B) is a urea adduct type latent curing agent or an epoxy resin amine adduct type latent curing agent.
[12] A cured product obtained by curing the thermally conductive resin composition according to any one of [1] to [11].
[13] An electric/electronic component, comprising applying the thermally conductive composition according to any one of [1] to [11] to the electric/electronic component to dissipate heat generated from the electric/electronic component to the outside. heat dissipation method.

Embodiments of the present invention will be described below. In addition, the present invention is not limited only to the following embodiments. Unless otherwise specified, measurements of operations and physical properties are performed under the conditions of room temperature (range of 20° C. to 25° C.)/relative humidity of 40 to 50% RH. Further, in this specification, "X to Y" indicating a range means "X or more and Y or less".

One embodiment of the present invention is a thermally conductive resin composition (hereinafter also referred to as composition) containing the following components (A) to (C):
(A) Epoxy resin (B) Adduct-type latent curing agent that is solid at 25 ° C. (C) A mixture of (C1) to (C3) below, wherein the mass ratio of (C1) to (C3) ((C1) /(C3)) is from 0.14 to 1.0 and the mass ratio of (C2) to (C3) ((C2)/(C3)) is from 0.25 to 1.5;
(C1) Thermally conductive powder with an average particle size of 0.01 μm or more and less than 2 μm (C2) Thermally conductive powder with an average particle size of 2 μm or more and less than 20 μm (C3) Thermally conductive powder with an average particle size of 20 μm or more and less than 150 μm .

The thermally conductive resin composition is excellent in low-temperature curability and handleability, and can form a cured product excellent in thermal conductivity. In this specification, “low temperature” refers to, for example, 150° C. or lower, preferably 120° C. or lower, more preferably 100° C. or lower, and still more preferably 80° C. or lower. The term "excellent in low-temperature curability" means that a cured product having no tackiness (stickiness) on the surface can be obtained when the composition is heated at the above temperature. Moreover, "excellent in handleability" means that the viscosity of the thermally conductive resin composition is low and the application work is easy.

The details of the thermoplastic resin composition according to the present invention are described below.

[Thermal conductive resin composition]
<(A) Component>
As the epoxy resin which is the component (A) of the present invention, any compound having two or more glycidyl groups in one molecule and not corresponding to the component (B) can be used without particular limitation. Component (A) includes, for example, epoxy resins having two glycidyl groups in one molecule (hereinafter also referred to as "bifunctional epoxy resins") and epoxy resins having three or more glycidyl groups in one molecule (hereinafter , also referred to as “polyfunctional epoxy resin”), and the like.

In the present invention, the component (A) is a bifunctional epoxy resin and a polyfunctional epoxy resin from the viewpoint of reducing the viscosity of the composition to improve handling properties, and from the viewpoint of improving the thermal conductivity and/or heat resistance of the cured product. It is preferable to use together with. At this time, the polyfunctional epoxy resin is more preferably a trifunctional or tetrafunctional epoxy resin, and even more preferably a tetrafunctional epoxy resin.

When a bifunctional epoxy resin and a polyfunctional epoxy resin are used in combination, the mass ratio (difunctional epoxy resin: polyfunctional epoxy resin) is preferably in the range of 30:70 to 70:30, more preferably 40: It ranges from 60 to 60:40. Within the above range, both the handleability of the composition and the thermal conductivity of the cured product can be highly compatible.

Component (A) can be used either in a liquid state at 25°C or in a solid state, but from the viewpoint of improving the handleability of the composition, it is preferably liquid at 25°C. Here, the term "liquid" means having fluidity, and specifically, when the component is tilted at an angle of 45°, it cannot retain its shape for 10 minutes or more and changes its shape.

From the viewpoint of further improving the effects of the present invention, the component (A) preferably has a viscosity at 25°C of 1 to 50 Pa·s, more preferably 3 to 40 Pa·s, and more preferably 5 to 30 Pa. • s is even more preferred. Here, the viscosity is a value measured by the method described in Examples below.

From the viewpoint of further improving the effects of the present invention, the epoxy equivalent of component (A) is preferably 50 to 250 g/eq, more preferably 100 to 200 g/eq. Here, the epoxy equivalent is a value measured according to JIS K7236:2001.

Although the bifunctional epoxy resin is not particularly limited, for example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type, bisphenol AD type epoxy resin, hydrogenated bisphenol type epoxy resin, 1 , 2-butanediol diglycidyl ether, 1,3-butanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 2,3-butanediol diglycidyl ether , 1,5-pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,4-cyclohexanedimethanol diglycidyl ether. Among these, bisphenol A-type epoxy resins and bisphenol F-type epoxy resins are preferably used from the viewpoint of excellent adhesiveness to aromatic polyester resins and high fluidity of the composition (low viscosity). Also, these may be used alone or in combination.

Examples of polyfunctional epoxy resins include, but are not limited to, novolac epoxy resins such as phenol novolak epoxy resins and cresol novolak epoxy resins; , N-diglycidylaniline), tetraglycidyldiaminodiphenylmethane, tetraglycidyl-m-xylylenediamine, and other glycidylamine compounds; and naphthalene-type epoxy resins having four glycidyl groups. These compounds may be used alone, or two or more of them may be mixed and used.

Commercially available products of component (A) are not particularly limited. Epiclon (registered trademark) 830, 850, 830LVP, 850CRP, 835LV, HP4032D, 703, 720, 726, 820 (manufactured by DIC Corporation); EP4100, EP4000, EP4080, EP4085, EP4088, EPU6, EPU7N, EPR4023, EPR1309 , EP4920 (manufactured by ADEKA Corporation); TEPIC (manufactured by Nissan Chemical Industries, Ltd.); KF-101, KF-1001, KF-105, X-22-163B, X-22-9002 (manufactured by Shin-Etsu Chemical Co., Ltd.) Denacol (registered trademark) EX411, 314, 201, 212, 252 (manufactured by Nagase ChemteX Corporation); DER-331, 332, 334, 431, 542 (manufactured by Dow Chemical Co.); YH-434, YH-434L ( Nippon Steel Sumitomo Chemical Co., Ltd.) and the like, but are not limited to these.

<(B) Component>
Component (B) used in the present invention is an adduct-type latent curing agent that is solid at 25°C. Here, the term "solid" refers to a material that does not have fluidity, and specifically refers to the ability to retain its shape for 10 minutes or more when the component is tilted at an angle of 45°. The mixture of components (A) and (B) is stable without heating (for example, 25°C), but by heating to 70 to 170°C (preferably 70 to 150°C), component (B) acts as a curing agent to cure component (A). Here, the adduct type refers to, for example, a compound obtained by partially reacting an epoxy resin and an amine compound, or a compound obtained by partially reacting an amine compound and an isocyanate compound or a urea compound. In particular, in the present invention, among conventional curing agents for epoxy resins, the component (B) is selected and combined with the components (C1) to (C3) described below to improve the handleability of the composition and the heat resistance of the cured product. It can be compatible with conductivity. On the other hand, when the component (B) is not contained, the viscosity of the composition becomes high and the handleability is poor, and/and the thermal conductivity of the cured product becomes insufficient (see Comparative Examples 1 to 3).

From the viewpoint of further improving the effects of the present invention, the average particle size of component (B) is preferably in the range of 0.1 to 100 μm, more preferably in the range of 1 to 30 μm, and even more preferably in the range of 2 to 15 μm. , more preferably 3 to 10 μm, and particularly preferably more than 5 μm and less than 10 μm. Here, the average particle size of component (B) is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by the laser diffraction scattering method.

From the viewpoint of low-temperature curability, the upper limit of the softening temperature of component (B) is, for example, 170° C. or lower, preferably 160° C. or lower, more preferably 150° C. or lower, and particularly preferably 145° C. or lower. . From the viewpoint of handleability, the lower limit of the softening temperature of component (B) is, for example, 80° C. or higher, preferably 90° C. or higher, more preferably 100° C. or higher, and particularly preferably 110° C. or higher. be. The method for measuring the softening temperature is obtained by a test method conforming to JIS K7234:1986.

The component (B) is not particularly limited, but is a reaction product (urea adduct-type latent curing agent) obtained by reacting an amine compound with an isocyanate compound or a urea compound, or a reaction product (epoxy A resin amine adduct type latent curing agent) is preferred. These may be used in combination. Among them, the epoxy resin amine adduct type latent curing agent is preferable from the viewpoint of achieving both the handleability of the composition and the thermal conductivity of the cured product at a higher level.

When the component (B) is a urea adduct type latent curing agent, the softening temperature thereof is preferably 110°C or higher, more preferably 120°C, from the viewpoint of reducing the viscosity of the composition to improve handling properties. 130° C. or higher, particularly preferably 135° C. or higher. The method for measuring the softening temperature is the same as above.

Commercially available products of component (B) are not particularly limited, but examples of urea adduct type latent curing agents include Fujicure (registered trademark; 1050 (these are products of T&K TOKA Co., Ltd.). Examples of epoxy resin amine adduct type latent curing agents include Amicure (registered trademark, hereinafter the same) PN-23, Amicure PN-H, Amicure PN-31, Amicure PN-40, Amicure PN-50, and Amicure PN-F. , Amicure PN-23J, Amicure PN-31J, Amicure PN-40J, Amicure MY-24, Amicure MY-25, Amicure MY-R, and Amicure PN-R (products of Ajinomoto Fine-Techno Co., Inc.). Also, these may be used alone or in combination.

The amount of component (B) in the present invention is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, and still more preferably 100 parts by mass of component (A). 15 to 30 parts by mass. When the amount of the component (B) is 5 parts by mass or more, the component (A) can be sufficiently cured, and when the amount is 50 parts by mass or less, the heat resistance of the cured product of the thermal conductive resin composition is superior.

<(C) Component>
The component (C) of the present invention includes (C1) a thermally conductive powder having an average particle size of 0.01 μm or more and less than 2 μm, (C2) a thermally conductive powder having an average particle size of 2 μm or more and less than 20 μm, and (C3) an average particle size. It is a mixture of thermally conductive powders with a diameter of 20 μm or more and less than 150 μm. By using the components (C1) to (C3) in combination with the other components of the present invention, there is a remarkable effect that both the handleability of the composition and the thermal conductivity of the cured product can be achieved.

The average particle diameter of the component (C1) is 0.01 μm or more and 2 μm (2.0 μm ), more preferably 0.1 μm or more and 1.7 μm or less, even more preferably 0.2 μm or more and 1.5 μm or less, and particularly preferably 0.5 μm or more and 1.2 μm or less.

In addition, the average particle size of the component (C2) is 2 μm (2.0 μm) or more from the viewpoint of obtaining a cured product with high thermal conductivity while reducing the viscosity of the thermally conductive resin composition to improve handling properties. It is preferably less than 20 µm, more preferably 2.2 µm or more and 15 µm or less, even more preferably 2.5 µm or more and 8 µm or less, and particularly preferably 3.0 µm or more and 5.0 µm or less.

In addition, the average particle size of the component (C3) is preferably 20 μm or more and 150 μm or less from the viewpoint of obtaining a cured product with high thermal conductivity while reducing the viscosity of the thermally conductive resin composition to improve handling properties. 23 μm or more and 100 μm or less is more preferable, 25 μm or more and 70 μm or less is even more preferable, and 30 μm or more and less than 50 μm is particularly preferable.

Here, the average particle size of the components (C1) to (C3) is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by the laser diffraction scattering method.

In the composition of the present invention, the mass ratio of component (C1) to component (C3) ((C1)/(C3)) is 0.14 to 1.0. When (C1)/(C3) is less than 0.14, the composition has high viscosity and poor handleability, and the resulting cured product has insufficient thermal conductivity (see Comparative Example 4). On the other hand, when (C1)/(C3) exceeds 1.0, the composition has a very high viscosity and is difficult to handle, making it difficult to form a cured product (see Comparative Examples 6 and 7). From the viewpoint of further improving the effects of the present invention, (C1)/(C3) is preferably 0.16 to 0.90, more preferably 0.18 to 0.80, and even more preferably 0 0.20 to 0.70, particularly preferably 0.25 to 0.65.

In the composition of the present invention, the mass ratio of component (C2) to component (C3) ((C2)/(C3)) is from 0.25 to 1.5. When (C2)/(C3) is less than 0.25, the composition has high viscosity and poor handleability, and the resulting cured product has insufficient thermal conductivity (see Comparative Example 5). On the other hand, when (C2)/(C3) exceeds 1.5, the composition has a very high viscosity and is difficult to handle, making it difficult to form a cured product (see Comparative Examples 6 and 8). From the viewpoint of further improving the effects of the present invention, (C2)/(C3) is preferably 0.27 to 1.2, more preferably 0.30 to 1.0, and even more preferably 0 0.40 to 0.95.

Therefore, from the viewpoint of both handleability and thermal conductivity of the cured product, (C1) / (C3) is 0.14 to 1.0 and (C2) / (C3) is 0.25 to 1.5. , preferably (C1) / (C3) is 0.16 to 0.9 (0.90) and (C2) / (C3) is 0.27 to 1.2, more preferably (C1) / ( C3) is from 0.18 to 0.8 (0.80) and (C2)/(C3) is from 0.3 (0.30) to 1.0.

The mixing ratio of the components (C1) to (C3) is such that the total of (C1), (C2) and (C3) is 100% by mass, and the component (C1) is 5 to 60% by mass, and the component (C2) is 10 to 10% by mass. 65% by mass, and component (C3) is preferably 30 to 85% by mass, component (C1) is 5 to 30% by mass, component (C2) is 10 to 50% by mass, and component (C3) is 30% by mass. It is more preferably to 80% by mass, the (C1) component is 7 to 28% by mass, the (C2) component is 15 to 40% by mass, and the (C3) component is 40 to 70% by mass. preferable. When the mixing ratio of the components (C1) to (C3) is within the above range, both the handling property and the thermal conductivity of the cured product can be satisfactorily achieved.

From the viewpoint of further improving the effects of the present invention, the content of component (C1) is preferably 80 to 300 parts by mass, more preferably 120 to 250 parts by mass, per 100 parts by mass of component (A). be.

From the same viewpoint, the content of component (C2) is preferably 150 to 400 parts by mass, more preferably 180 to 350 parts by mass, per 100 parts by mass of component (A).

From the same point of view, the content of component (C3) is preferably 250 to 500 parts by mass, more preferably 300 to 450 parts by mass, per 100 parts by mass of component (A).

The content of the component (C) (that is, the total content of the components (C1) to (C3)) is not particularly limited, but is, for example, 55 to 99 mass with respect to the entire thermally conductive resin composition of the present invention. % is preferred, 60 to 95 mass % is more preferred, 70 to 93 mass % is even more preferred, 75 to 90 mass % is even more preferred, and 80 to 86 mass % is particularly preferred. If it is 55% by mass or more, the thermal conductivity performance is sufficient, and if it is 99% by mass or less, both workability (handlability of the composition) and thermal conductivity of the cured product can be achieved.

The components (C1) to (C3) are each independently at least one thermally conductive powder selected from the group consisting of alumina, zinc oxide, aluminum nitride, boron nitride, carbon and diamond. More preferably, it is at least one thermally conductive powder independently selected from the group consisting of alumina, aluminum nitride and boron nitride, since it has excellent thermal conductivity. From the viewpoint of further improving the effects of the present invention, at least one of the components (C1) to (C3) is preferably alumina, and it is particularly preferable that all of the components (C1) to (C3) are alumina. . Moreover, the (C) component may be surface-treated. Also, these may be used alone or in combination.

The shape of the components (C1) to (C3) is preferably spherical or amorphous.

As used herein, the term "spherical" includes not only perfect spheres but also shapes such as nearly spherical and elliptical. More specifically, "spherical" means that the average circularity is 0.4 or more.

As used herein, "amorphous" refers to a shape having corners other than a spherical shape (eg, needle-like, fibrous, scale-like, dendritic, tabular, crushed shape, etc.). More specifically, "irregular" means that the average circularity is less than 0.4. Furthermore, when the component (C) is a mixture containing spherical thermally conductive powder and amorphous thermally conductive powder, a cured product with further improved thermal conductivity can be obtained.

Here, the degree of circularity is obtained by obtaining a projected particle image using, for example, a flow-type particle image analyzer FPIA-3000 (manufactured by Malvern Co., Ltd.), and X is the perimeter of a circle having a projected area equal to that of the projected particle image. It is a value expressed by X/Y, where Y is the length of the contour line of the particle projection image. Furthermore, the average circularity is calculated by summing the circularity of each particle and dividing by the total number of particles.

Considering the handleability of the composition, the shape of component (C1) is preferably spherical. On the other hand, considering the thermal conductivity of the cured product, the shape of the component (C1) is preferably amorphous.
Considering handleability, the shape of the component (C2) is preferably spherical. In consideration of handleability, the shape of component (C3) is preferably spherical. Therefore, in one embodiment of the invention, the (C2) and (C3) components are spherical thermally conductive powders.

<Optional component>
The thermally conductive resin composition of the present invention may further contain optional additive components within a range that does not impair its properties. Examples of the components include plasticizers, solvents, diluents, adhesion improving components such as silane coupling agents, dispersants, leveling agents, wetting agents, surfactants such as antifoaming agents, antistatic agents, and surface lubricants. agents, rust inhibitors, antiseptics, viscoelasticity modifiers, rheology modifiers, colorants, antioxidants such as ultraviolet absorbers, and non-thermally conductive fillers. Furthermore, the thermally conductive resin composition of the present invention may contain polymeric materials such as polyester resins, polycarbonate resins, polyacrylic resins, polyurethane resins, and polyvinyl resins for the purpose of adjusting viscoelasticity.

The thermally conductive resin composition of the present invention can be produced by a conventionally known method. For example, the above components (A), (B), (C1), (C2) and (C3), and optionally optional components are blended in a predetermined ratio, and then a known mixing means such as a mixer is used. and mixed at a temperature of 10 to 70° C. for preferably 0.1 to 5 hours.

From the viewpoint of handleability, the thermally conductive resin composition of the present invention is preferably liquid at 25°C. For example, 0.5 Pa·s or more). Here, the viscosity is a value measured by the method described in Examples below.

<Application>
INDUSTRIAL APPLICABILITY The thermally conductive resin composition of the present invention is excellent in low-temperature curability and handleability, and can form a cured product with excellent thermal conductivity. Heat dissipation, heat dissipation of electronic substrates, heat dissipation of optical pickup modules, heat dissipation of camera modules, heat dissipation of power semiconductors, heat dissipation of inverters for HEV, FCV, EV, heat dissipation of converters for HEV, FCV, EV, ECU for EV It can be used for various purposes such as heat dissipation of parts.

<Heat dissipation method>
A cured product can be formed on the electrical/electronic component by applying the thermally conductive composition of the present invention to the electrical/electronic component and heat-treating the composition. Since the formed cured product has excellent thermal conductivity, the heat generated from the electric/electronic component can be radiated to the outside through the cured product. The electrical/electronic component is not particularly limited, and includes those described in the above <Application>.

The heat treatment conditions are not particularly limited, but in the case of plastic electric and electronic parts, for example, the heat treatment is performed at 150° C. or lower (eg, 40 to 120° C.) for 5 to 120 minutes.

Therefore, according to another aspect of the present invention, there is provided heat dissipation for an electric/electronic component, which comprises applying the above-mentioned thermally conductive composition to the electric/electronic component to radiate heat generated from the electric/electronic component to the outside. A method is provided. Moreover, according to another aspect of the present invention, there is provided a cured product obtained by curing the above thermally conductive resin composition.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by the following examples.

<Preparation of Thermally Conductive Resin Composition>
The following components (A), (B) (or comparative components of (B)), and (C) are collected in parts by weight shown in Table 1 and mixed at normal temperature (25°C) with a planetary mixer for 60 minutes. Then, a thermally conductive resin composition was prepared, and various physical properties were measured as follows.

<(A) Component>
a1: Bisphenol F-type bifunctional epoxy resin (jER (registered trademark) 806, manufactured by Mitsubishi Chemical Corporation, viscosity 15 to 25 Pa s (25°C), epoxy equivalent 160 to 170 g/eq) that is liquid at 25°C
a2: Glycidylamine-type tetrafunctional epoxy resin (tetraglycidyldiaminodiphenylmethane, YH-434L, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., viscosity 6-9 Pa s (25° C.), epoxy equivalent 115-119 g/eq, which is liquid at 25° C. )
<(B) Component>
b1: A urea adduct type latent curing agent that is solid at 25°C, has an average particle size of 7 µm and a softening temperature of 140°C (Fujicure FXR-1030 manufactured by T&K TOKA Co., Ltd.)
b2: A urea adduct-type latent curing agent that is solid at 25°C, has an average particle size of 7 µm, and a softening temperature of 120°C (Fujicure FXE-1000 manufactured by T&K TOKA Co., Ltd.)
b3: Epoxy resin amine adduct type latent curing agent that is solid at 25° C., has an average particle size of 9 μm and a softening temperature of 115° C. (Amicure MY-24 manufactured by Ajinomoto Fine-Techno Co., Inc.)
<Comparison component of (B)>
b'1: 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (2MA-OK manufactured by Shikoku Kasei Kogyo Co., Ltd., which is liquid at 25 ° C. )
b'2: 1,3-bis(hydrazinocarbonoethyl)-5-isopropylhydantoin (Amicure VDH manufactured by Ajinomoto Fine-Techno Co., Inc.)
b'3: 3-phenyl-1,1-dimethylurea (Omicure 94 manufactured by PI Japan Co., Ltd.)
b'4: Dicyandiamide with an average particle size of 4 μm (Omicure DDA-5 manufactured by PI Japan Co., Ltd.)
<(C) Component>
c1-1: Irregular alumina powder with an average particle size of 1.0 μm (manufactured by Showa Denko K.K., average circularity of less than 0.4)
c1-2: Spherical alumina powder with an average particle diameter of 1.0 μm (manufactured by Sumitomo Chemical Co., Ltd., average circularity of 0.4 or more)
c2: spherical alumina powder with an average particle diameter of 3.0 μm (manufactured by Nippon Steel & Sumikin Materials Co., Ltd., average circularity of 0.4 or more)
c3: Spherical alumina powder with an average particle size of 35.0 μm (manufactured by Nippon Steel & Sumikin Materials Co., Ltd., average circularity of 0.4 or more)
Test methods used in Examples and Comparative Examples are as follows.

<Viscosity measurement>
The viscosities of the thermally conductive resin compositions of Examples and Comparative Examples in Table 1 were evaluated. Viscosity was measured at 25° C. using an EHD viscometer (TV-33 manufactured by Toki Sangyo Co., Ltd.). The measurement conditions are as follows. The lower the viscosity, the better the coating workability and the better the handleability. Particularly in the present invention, the viscosity of the composition is preferably less than 250 Pa·s, more preferably less than 220 Pa·s, from the viewpoint of handling properties of the composition. In Table 1, "*" indicates that the viscosity was too high to be measured:
[Measurement condition]
Cone rotor: 3° x R14
Rotation speed: 0.5 rpm.

<Thermal conductivity measurement>
The thermally conductive resin compositions of Examples and Comparative Examples in Table 1 were applied to a fluororesin plate to a thickness of 0.5 mm, and heated at 80°C for 1 hour to cure the composition. , to prepare a test piece. The thermal conductivity is measured using a thermal conductivity meter (QTM-D3 manufactured by Kyoto Electronics Industry Co., Ltd.), and the thermal conductivity (W / (m K)) of the surface on which the cured product of the test piece is formed is 25. Measured in °C. It is preferable that the cured product has a higher thermal conductivity because heat is more easily transmitted. In particular, in the present invention, the thermal conductivity of the cured product is preferably 3.8 W/(m·K) or more from the viewpoint of the thermal conductivity of the cured product. It is suggested that there is a significant difference in the performance of dissipating the heat generated from the electric/electronic component to the outside between when the lower limit is satisfied and when it is not satisfied. The thermal conductivity of the cured product is preferably 4.0 W/(m·K) or more. All of the thermally conductive resin compositions according to the examples in Table 1 were heat-treated at 80° C. for 1 hour to obtain cured products with no tack (stickiness) on the surface, so they have low-temperature curability. was recognized. Moreover, in Table 1, "**" represents that the viscosity of the composition was too high and the cured product could not be formed.

From the results of Examples 1 to 11 in Table 1, it was confirmed that the thermally conductive resin composition of the present invention is excellent in low-temperature curability and handleability, and can form a cured product excellent in thermal conductivity.

On the other hand, in the compositions containing the curing agents b'1 to b'4 that are not the component (B) of the present invention, the compositions of Comparative Examples 1 and 3 are compared to the compositions of Examples (C) It was confirmed that the thermal conductivity of the cured product formed was poor despite the high content of the components. Moreover, it was confirmed that the composition of Comparative Example 2 had a high viscosity and was inferior in handleability.

In addition, although it contains the components (C1) to (C3) of the present invention, the composition (C1)/(C3) is less than 0.14 or (C2)/(C3) is less than 0.25 ( It was confirmed that Comparative Examples 4 and 5) were inferior in both handleability and thermal conductivity of the formed cured product.

In addition, although it contains the components (C1) to (C3) of the present invention, the composition (C1)/(C3) exceeds 1.0 or/and (C2)/(C3) exceeds 1.5 ( Comparative Examples 6 to 8) had very high viscosity and were difficult to handle, and could not form a cured product.

INDUSTRIAL APPLICABILITY The thermally conductive resin composition of the present invention is excellent in low-temperature curability and handleability, and can form a cured product with excellent thermal conductivity. etc., and can be applied to a wide range of fields.

This application is based on Japanese Patent Application No. 2017-202015 filed on October 18, 2017, the disclosure of which is incorporated herein by reference.

Claims (13)

A thermally conductive resin composition containing the following components (A) to (C):
(A) Epoxy resin (B) Adduct-type latent curing agent that is solid at 25°C (C) A mixture of components (C1) to (C3) below, wherein the mass ratio of component (C1) to component (C3) is 0.14 to 1.0, and the mass ratio of component (C2) to component (C3) is 0.25 to 1.5;
(C1) Thermally conductive powder with an average particle size of 0.01 μm or more and less than 2 μm (C2) Thermally conductive powder with an average particle size of 2 μm or more and less than 20 μm (C3) Thermally conductive powder with an average particle size of 20 μm or more and less than 150 μm . wherein said components (C1) to (C3) are each independently at least one thermally conductive powder selected from the group consisting of alumina, zinc oxide, aluminum nitride, boron nitride, carbon and diamond; Item 1. The thermally conductive resin composition according to Item 1. 3. The thermally conductive resin composition according to claim 1, wherein the components (C1) to (C3) are spherical or amorphous. The thermally conductive resin composition according to any one of claims 1 to 3, wherein the component (C) is a mixture containing spherical thermally conductive powder and amorphous thermally conductive powder. In the total 100% by mass of the components (C1), (C2) and (C3), the component (C1) is 5 to 60% by mass, the component (C2) is 10 to 65% by mass, and the component (C3) is 30 to 60% by mass. The thermally conductive resin composition according to any one of claims 1 to 4, containing 85% by mass. The thermally conductive resin composition according to any one of claims 1 to 5, wherein the content of component (C) in the thermally conductive resin composition is 55 to 99% by mass. The thermally conductive resin composition according to any one of claims 1 to 6, wherein the component (A) is liquid at 25°C. The thermally conductive resin composition according to any one of claims 1 to 7, comprising 5 to 50 parts by mass of component (B) with respect to 100 parts by mass of component (A). The thermally conductive resin composition according to any one of claims 1 to 8, which is liquid at 25°C. The thermally conductive resin composition according to any one of claims 1 to 9, wherein the component (B) has an average particle size in the range of 0.1 to 100 µm. The thermally conductive resin composition according to any one of claims 1 to 10, wherein the component (B) is a urea adduct type latent curing agent or an epoxy resin amine adduct type latent curing agent. A cured product obtained by curing the thermally conductive resin composition according to any one of claims 1 to 11. A heat dissipation method for an electric/electronic component, comprising applying the thermally conductive composition according to any one of claims 1 to 11 to the electric/electronic component to radiate heat generated from the electric/electronic component to the outside. .