JP6898543B2 - A thermally conductive resin composition and a method for producing a molded product using the same. - Google Patents

Description

The present invention relates to a thermosetting resin composition and a method for producing a molded product using the same, and specifically uses a thermosetting resin composition containing a thermosetting resin, scaly graphite and carbon fibers, and a heat conductive resin composition using the same. It relates to the manufacturing method of the molded article.

Conventionally, a metal material has been used as a material that requires high thermal conductivity, but in recent years, a product has been manufactured using a thermally conductive resin composition containing a resin for the purpose of miniaturization, weight reduction, and the like. Is being done.
As such a thermally conductive resin composition, a thermally conductive resin composition containing a thermosetting resin, scaly graphite, and carbon fibers is known (Patent Document 1), and adjacent scaly graphite and scaly graphite are known. The carbon fibers in the resin form a heat conduction path with the resin to generate good heat conductivity.
Further, Patent Document 1 exemplifies a compression molding method such as transfer molding, a casting method such as cast molding, and an injection molding method such as RIM molding when manufacturing a molded product using the above-mentioned heat conductive resin composition. ing.

Japanese Unexamined Patent Publication No. 2015-937

However, in Patent Document 1, if the total volume of scaly graphite and carbon fibers exceeds 70% with respect to the total volume of the heat conductive resin composition, the moldability deteriorates. It is said that it cannot be contained to improve thermal conductivity.
In view of such problems, the present invention provides a thermally conductive resin composition capable of containing scaly graphite and carbon fibers in a higher proportion, and a method for producing a molded product using the same.

That is, the thermally conductive resin composition according to the invention of claim 1 is a thermally conductive resin composition containing a thermosetting resin, scaly graphite, and carbon fibers.
The aspect ratio of the scaly graphite is 10 or more,
The thermally conductive resin composition has a powdery state and is in the form of powder.
Each of the particles constituting the powder is coated with the thermosetting resin in which scaly graphite is dissolved in an organic solvent , and the plane direction of each scaly graphite is randomly oriented.
The ratio of the total volume of the scaly graphite and the carbon fiber to the total volume is more than 70% and 83% or less.

Further, the method for producing a molded product using the thermally conductive resin composition according to the invention of claim 2 is a molded article using a thermally conductive resin composition containing a thermosetting resin, scaly graphite and carbon fibers. In the manufacturing method of
The scaly graphite and carbon fibers are mixed with a solution of the thermosetting resin in an organic solvent, and dispersed until the organic solvent volatilizes and becomes a paste.
After the paste-like mixture was dried to prepare a solid tablet, the tablet was crushed so that the scaly graphite was coated with the thermosetting resin on each of the constituent particles, and the plane direction of each scaly graphite was changed. A powdery thermosetting resin composition suitable for random use.
The powdery heat conductive resin composition is compressed at room temperature to prepare a temporary molded product having substantially the same shape as the molded product, and then the temporary molded product is heat-press molded to obtain the scaly graphite. It is characterized in that the molded product having a surface direction oriented in a certain direction is obtained.

According to the invention of claim 1, the thermally conductive resin composition has a powdery state, and the powdery thermally conductive resin composition is compression-molded at room temperature to temporarily form a molded product having substantially the same shape. By producing the product, it becomes possible to obtain a molded product containing the above-mentioned scaly graphite and carbon fiber in a higher proportion.

According to the invention of claim 2, the thermosetting resin in which the scaly graphite and carbon fibers are mixed is made into a paste, and the paste-like mixture is dried and pulverized to form a powdery thermosetting resin composition. You can get things.
Then, by heat-press molding this powdery heat conductive resin composition, a molded product containing scaly graphite and carbon fibers in a higher proportion can be obtained.

The figure which showed the structure of the material of the heat conductive resin composition which concerns on this Example. The figure explaining the manufacturing method of a molded article. The figure which showed the structure of the material in a molded article.

Hereinafter, the present embodiment will be described. FIG. 1 is a schematic view showing the structure of the thermally conductive resin composition 1 according to the present invention, and the thermally conductive resin composition 1 of the present embodiment has thermal conductivity. It can be used as a material for manufacturing a molded product 2 such as an excellent heat radiating plate.
The heat conductive resin composition 1 has a powdery state when it is crushed, and the particles constituting the powder are a thermosetting resin 3 such as phenol and epoxy, and a powder having a substantially flat plate shape, respectively. It is composed of scaly graphite 4 and fibrous carbon fibers 5, of which the thermosetting resin is not thermoset.
The diameter of the particles constituting the powder is about 10 to 250 μm, and the scaly graphite 4 is randomly oriented in the plane direction of each of the particles, and is coated with the thermosetting resin 3 and adjacent to each other. The scaly graphite 4 is in a state of being adhered to each other. The carbon fiber 5 is in a state of being inserted between the scaly graphite 4 and the scaly graphite 4.
In the heat conductive resin composition 1 having the above structure, the ratio of the total volume of the scaly graphite 4 and the carbon fiber 5 to the total volume is more than 70% and 83% or less. ..

In this example, as the thermosetting resin 3, a phenol resin, an epoxy resin, a polyimide, a polyamide-imide, or the like can be used, and these can also be used in combination.
As the powdery scaly graphite 4, either α-graphite or β-graphite can be used, and graphene may be used. Further, those having a diameter in the plane direction of 10 to 250 μm and an aspect ratio of 10 or more can be used.
As the carbon fiber 5, carbon nanofibers and carbon nanotubes can be used, and those having a diameter of 10 to 30 μm and a fiber length of 100 to 200 μm can be used. Moreover, you may use these together.

The method for producing the thermally conductive resin composition 1 according to the present embodiment will be described with reference to FIG.
First, a paste-like mixture preparation step of preparing a paste-like mixture composed of the thermosetting resin 3, scaly graphite 4, and carbon fiber 5 is performed (FIG. 2A). A conventionally known stirrer can be used for mixing.
Specifically, first, the thermosetting resin 3 is dissolved with an organic solvent such as methyl ethyl ketone (MEK), and the scaly graphite 4 and the carbon fiber 5 are added to the obtained solution of the thermosetting resin 3. Further stirring is carried out to disperse the scaly graphite 4 and the carbon fibers 5 in the solution until the organic solvent volatilizes and the mixture becomes a paste.
By dispersing the scaly graphite 4 and the carbon fiber 5 in the solution of the thermosetting resin 3, the solution adheres to the surface of the scaly graphite 4, and the adjacent scaly graphite 4 and the scaly graphite 4 are combined. The carbon fiber 5 will be located between them.

Next, a drying step of drying the paste-like mixture to prepare a tablet 11 is performed (FIG. 2 (b)).
Specifically, the paste-like mixture obtained in the above-mentioned paste-like mixture preparation step may be thinly spread and placed in a room temperature environment to volatilize the above-mentioned organic solvent. At that time, air is blown by a blower. You may.
At this time, since the scaly graphite 4 in the tablet 11 is in a dispersed state in the paste-like mixture, the plane direction thereof is in a random direction as shown in FIG. There is.

Next, a crushing step of crushing the tablet 11 obtained in the drying step is performed (FIG. 2 (c)).
Specifically, the tablet 11 may be put into a crusher such as a mixer and pulverized into a powder, whereby the powdery thermally conductive resin composition 1 according to the present invention can be obtained.
Here, since the crushed powdery heat conductive resin composition 1 is only crushed from the tablet 11, the plane direction of the scaly graphite 4 in each particle constituting the powder is as shown in FIG. It is in a state of facing a random direction.

Subsequently, a method for producing the molded product 2 using the thermally conductive resin composition 1 produced by the above production method will be described.
First, a temporary molding step of pressing and compressing the powdery heat conductive resin composition 1 at room temperature to prepare a temporary molded product 2 is performed (FIG. 2 (d)).
Specifically, the powdery heat conductive resin composition 1 is put into a mold formed in the shape of a predetermined molded product 2, and this is pressure-compressed at room temperature to obtain a substantially molded product 2. A temporarily molded product 2'having a shape can be obtained.
At this time, in the temporarily molded product 2', since it is not overheated during molding, the thermosetting resin does not cause a cross-linking reaction, and the particles constituting each heat conductive resin composition 1 do not adhere to each other and are in a very brittle state. It has become. Further, the plane direction of the scaly graphite 4 is also in a state of facing a random direction as shown in FIG.

Next, a heat molding step of obtaining a molded product 2 as a finished product is performed by heat-pressing and compressing the temporarily molded product 2'obtained in the temporary molding step (FIG. 2 (e)).
Specifically, the temporary molded product 2'is put into a preheated mold, and the temporary molded product 2'is heat-pressed and compressed, whereby the thermosetting resin 3 in the heat conductive resin composition 1 is obtained. The molded product 2 can be obtained by curing by a cross-linking reaction.
At that time, the thermosetting resin 3 is softened once, but at the same time, since the temporary molded product 2'is compressed by the mold, the scaly graphite 4 in the softened resin moves and its surface direction is added. It is designed to face in a direction substantially orthogonal to the direction of pressure.

In the molded product 2 thus obtained, as shown in FIG. 3, the scaly graphite 4 is in a state of being laminated in a layered state in which the plane direction is oriented in a certain direction, and the carbon fiber 5 is located between them. It has become.
With such a configuration, heat can be efficiently conducted by the scaly graphite 4 laminated in layers, and these heats can be satisfactorily transferred by the carbon fibers 5 located between them.
Moreover, since the total volume of the scaly graphite 4 and the carbon fiber 5 is larger than the conventional volume with respect to the total volume, the amount of resin between the adjacent scaly graphite 4 is small. ..
That is, since the amount of the thermosetting resin having an insulating property between the scaly graphite 4 and the scaly graphite 4 can be reduced, heat conduction can be performed more efficiently.

Hereinafter, the product 2 as a molded product 2 manufactured by using the heat conductive resin composition 1 according to the present invention and the molded product 2 manufactured by using another heat conductive resin composition 1 used for comparison are used. Experiments were conducted on the thermal conductivity of each of the comparative products.
The product produced using the thermally conductive resin composition 1 according to this example uses a phenol resin as the thermosetting resin 3 and a scaly graphite 4 having a planar diameter of 10 to 30 μm. As the carbon fiber 5, those having a length of 100 to 200 μm were used.
Then, using the above manufacturing method, a test piece having a diameter of 10.0 mm and a thickness of 2 ± 1 mm was prepared. At that time, the ratio of the total volume of the scaly graphite 4 and the carbon fiber 5 to the total volume of the heat conductive resin composition 1 was set to 83%.

Then, the density, specific heat, and thermal diffusivity of this product were measured by conventionally known methods, and the thermal conductivity was calculated from these values.
As a method for measuring the density, an underwater substitution method at room temperature (25 ° C.) was used.
A laser flash method was used as a method for measuring the specific heat and thermal diffusivity, and TC-7000H (manufactured by ULVAC Riko Co., Ltd.) was used as the measuring device.
Then, the thermal conductivity was calculated by substituting the measured values of the density, the specific heat, and the thermal diffusivity into the following equations.
Thermal conductivity (W / m · K) = density (kg / m ³ ) x specific heat (kJ / kg · K) x thermal diffusivity (m ² / s) x 1000 (kJ / J)
As a result, the thermal conductivity of the product according to the present invention was 122 W / m · K, which was good as well as having good thermal conductivity and no chipping in moldability.

In the method for manufacturing a molded product in the above embodiment, if the shape of the molded product 2 is not complicated, the temporary molding step can be omitted.
Specifically, when the powdery heat conductive resin composition 1 can be distributed to the mold used in the molding step, the heat conductive resin composition 1 is directly charged and heated. By pressure compression, the molded product 2 can be obtained, and the molded product can contain scaly graphite 4 in a high proportion.

1 Thermally conductive resin composition 2 Molded product 2'Temporarily molded product 3 Thermosetting resin
4 scaly graphite 5 carbon fiber 11 tablet

Claims (2)

In a thermally conductive resin composition containing a thermosetting resin, scaly graphite, and carbon fibers,
The aspect ratio of the scaly graphite is 10 or more,
The thermally conductive resin composition has a powdery state and is in the form of powder.
Each of the particles constituting the powder is coated with the thermosetting resin in which scaly graphite is dissolved in an organic solvent , and the plane direction of each scaly graphite is randomly oriented.
A thermally conductive resin composition, wherein the ratio of the total volume of the scaly graphite and carbon fibers to the total volume is more than 70% and 83% or less. In a method for producing a molded product using a thermally conductive resin composition containing a thermosetting resin, scaly graphite, and carbon fibers.
The scaly graphite and carbon fibers are mixed with a solution of the thermosetting resin in an organic solvent, and dispersed until the organic solvent volatilizes and becomes a paste.
After the paste-like mixture was dried to prepare a solid tablet, the tablet was crushed so that the scaly graphite was coated with the thermosetting resin on each of the constituent particles, and the plane direction of each scaly graphite was changed. A powdery thermosetting resin composition suitable for random use.
The powdery thermally conductive resin composition is compressed at room temperature to prepare a temporary molded product having substantially the same shape as the molded product, and then the temporary molded product is heat-press molded to obtain the scaly graphite. A method for producing a molded product using a thermally conductive resin composition, which comprises obtaining the molded product having a surface direction oriented in a certain direction.

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