JP2015000937A - Heat-conductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-conductive resin composition using a specific combination of inexpensive and general-purpose heat-conductive filler, which has excellent moldability and provides a molded article having high heat conductivity.SOLUTION: The heat-conductive resin composition comprises (a) a base resin comprising a thermosetting resin or a thermoplastic resin, in which is loaded (b) scaly filler and (c) fibrous filler, both of which have heat conductivity. One or more scaly filler surfaces are arranged in the same plane to form a planar structure; the planar structures are arranged with the same plane direction to form one or more layer structures; in a resin layer which is in contact with the planar structure, the fibrous filler forms a dispersion layer; and the fibrous filler forms a heat-conduction path between the layers.

Description

  The present invention relates to a thermally conductive resin composition, and more particularly to an economical thermally conductive resin composition having high thermal conductivity.

  In recent years, with the miniaturization and high performance of electric / electronic components, heat generation in the components has become remarkable, and there has been a problem that the performance of the equipment is deteriorated due to heat accumulation. Therefore, a material excellent in thermal conductivity is required from the viewpoint of safety and reliability. Conventionally, metal materials have been used for materials that require high thermal conductivity. However, materials are required to be lightweight and easy to process to reduce the size and performance of parts. Substitution is progressing. However, the resin has low thermal conductivity from the beginning, and there is a limit to increasing the thermal conductivity of the resin itself.

  Conventionally, the main technique has been to improve the thermal conductivity by highly filling an inorganic filler having a high thermal conductivity. Although a technique using a nanofiller alone can be seen, high filling is required to improve thermal conductivity. A large amount of nanofillers is not practical because it is difficult to uniformly disperse and the fluidity also deteriorates, resulting in poor moldability, and the nanofillers themselves are expensive.

  Although there is a method to increase the thermal conductivity by combining carbon fiber (CF) and other thermally conductive nanofillers, the essence is to improve the thermal conductivity by highly filling the nanofillers. It is not practical because of its poor quality and the high price of CF and nanofillers. In the combination of CF and nanofiller, CF existing as a line is inferior to flat filler existing as a surface in the ability to form a heat conduction path with the nanofiller. In addition, there is a composition of a combination of a flat filler and a nanofiller, but the thermal conductivity is improved by the special structure of the nanofiller. Essentially, the nanofiller is highly filled to improve the thermal conductivity. It is a way of thinking.

  Compared with CF, a flat filler may have a slight cost reduction effect, but nanofiller mass filling is still impractical in view of poor dispersibility and cost. There is also a technique for improving thermal conductivity by mixing a flaky aluminum filler and carbon nanotubes (CNT) in a resin (Patent Document 1). Although this technique is effective as a technique for improving the thermal conductivity to a certain extent, since soft aluminum is used among metals, if the filler is filled in such an amount that the aluminum fillers are in contact with each other, the aluminum is deformed, and the heat It becomes impossible to form a layer structure important for improving the conductivity. This can be inferred from the fact that the thermal conductivity anisotropy is not so large in the example of Patent Document 1. Therefore, it is difficult for a heat conductive resin composition comprising a combination of flaky aluminum filler and CNT to achieve a metal-like high heat conductivity (10 W / m · K or more).

  Patent Document 2 discloses a zinc oxide whisker comprising a core part and a needle-like crystal part extending from the core part, and a plate-like inorganic filler made of hexagonal boron nitride or plate-like aluminum oxide. An electrically insulating thermally conductive resin composition blended in a thermoplastic resin so that the total blending amount of the conductive filler is 10 to 70% by volume is disclosed. By combining zinc oxide whiskers and flat inorganic fillers such as boron nitride, a heat conduction path is formed efficiently, so that a higher thermal conductivity can be obtained than when the same amount is filled individually, It is described that high thermal conductivity can be imparted by adding a small amount of heat conductive filler and injection moldability is also good.

JP 2012-072363 A JP 2011-132264 A

  However, in the method of highly filling an inorganic filler with high thermal conductivity, there are problems of wear of a processing machine screw, deterioration of workability due to lowering of fluidity of the material, and deterioration of mechanical properties of the material. Even if the distance between the fillers is shortened, a resin that hinders heat conduction exists between the fillers, and the filler cannot form a heat conduction path connecting the gaps. Even if the filler with high thermal conductivity is highly filled, The effect obtained was limited. Moreover, the method of highly filling the nanofiller has poor dispersibility, and there has been a problem of deterioration in processability and quality stability. Moreover, the cost increase by mass filling of nanofillers and adoption of carbon fibers has been a problem. When a soft metal is used as in Patent Document 1, it becomes a problem whether the layer structure can be maintained even when the filling rate is increased, that is, the thermal conductivity can be further improved.

  Therefore, in view of the above-mentioned situation, the present invention intends to solve the problem by using a specific combination of inexpensive and general-purpose heat conductive fillers to obtain a molded product having excellent moldability and high thermal conductivity. It exists in the point which provides the heat conductive resin composition which can be performed.

  In order to solve the above-mentioned problems, the present invention provides (a) a base resin made of a thermosetting resin or a thermoplastic resin, and (b) a scaly filler and (c) a fibrous filler both having thermal conductivity. Forming a planar structure in which the surfaces of one or more scale-like fillers are aligned in the same plane, forming one or more layered structures in which the planar structure faces the same planar direction, A dispersed layer of fibrous filler is formed in the resin layer to be contacted, and the fibrous filler is formed by forming a heat conduction path between the layers (claim 1).

  Here, when the total of (a) base resin, (b) flaky filler, and (c) fibrous filler is 100% by volume, the total volume of (b) flaky filler and (c) fibrous filler is 5 to 70% by volume is preferable (claim 2).

  (C) The fibrous filler has a diameter of 10 nm to 30 μm, a fiber length of 1 μm to 3 mm, and an aspect ratio of 100 or more.

  Further, (c) the fibrous filler is more preferably one or more conductive fibrous fillers selected from the group consisting of carbon nanofibers (CNF) and carbon nanotubes (CNT).

  And when the sum total of (a) base resin, (b) scale-like filler, and (c) fibrous filler is 100 volume%, the compounding quantity of (c) fibrous filler is 0.1-15 volume%. (Claim 5).

  Moreover, it is preferable that the diameter of the surface direction of (b) scale-like filler is 0.1 micrometer-200 micrometers, and an aspect-ratio is 10 or more (Claim 6).

  (B) It is more preferable that the scaly filler is one or more conductive scaly fillers selected from the group consisting of graphite and graphene.

  The thermally conductive resin composition of the present invention as described above comprises (a) a base resin composed of a thermosetting resin or a thermoplastic resin, both having thermal conductivity (b) a scale-like filler and (c) a fiber. Forming a planar structure in which the surfaces of one or more scaly fillers are aligned in the same plane, and forming one or more layered structures in which the planar structure faces the same planar direction, By forming a dispersion layer of fibrous filler in the resin layer in contact with the planar structure, and forming a heat conduction path between the fibrous filler, the heat conduction ability of the resin layer region that has hindered heat transfer is increased. Can be improved.

  Since the fibrous filler has a small size and a large aspect ratio, a heat conduction path can be efficiently formed between the layer structures formed by the scaly filler, so that a predetermined thermal conductivity can be achieved with a small amount of filler. Thereby, when compared with the conventional high filling amount technology in materials having the same thermal conductivity, problems such as screw wear, lower fluidity, and lower workability can be solved.

  The present invention does not improve the thermal conductivity of the nano fillers through the heat conduction path throughout the product as in the prior art, but has a structure in which a heat conduction path is formed in the resin layer between the scale-like filler layers. Therefore, a small amount of nanofiller is required, which is effective in reducing costs and improving the dispersibility of the filler.

  Further, since a scale-like filler, particularly graphite, is used as the first component of the filler, the ability to form a heat conduction path with the fibrous nanofiller is higher than that of carbon fiber, and the cost is generally low because the price is generally low. . Furthermore, by using highly rigid graphite, it is possible to fill the filler without deformation, and it is possible to form an efficient layer structure, and it is possible to realize a thermal conductivity that could not be achieved so far. It was.

It is a graph which shows the change of the thermal conductivity with respect to the graphite filling amount at the time of filling only graphite with epoxy resin, and the case where 2 volume% of carbon nanotubes are added to graphite. 1 schematically shows a cross-sectional structure of a molded article using the heat conductive resin composition of the present invention, in which (a) is a cross section of a plane parallel to the layer structure, and (b) is a plane orthogonal to the layer structure. A cross section is shown. It is a cross-sectional SEM image of the molded article using the heat conductive resin composition of this invention.

  First, the thermally conductive resin composition of the present invention is filled with (b) flaky filler and (c) fibrous filler, both having thermal conductivity in (a) base resin, and good thermal conductivity, It has heat dissipation and has excellent moldability.

  (A) Base resin will not be specifically limited if it is a thermosetting resin or a thermoplastic resin, Thermosetting resins, such as an epoxy resin, a phenol resin, a polyimide, a polyamideimide, a polypropylene, polyethylene, polyamide 6, polyamide 66, Polyamide 12, polyetheretherketone, polybutylene terephthalate, polyoxymethylene, liquid crystal polymer, polycarbonate, polylactic acid, and the like, preferably a thermoplastic resin having heat resistance higher than that of polypropylene. These can be used alone or in combination of two or more.

  (B) It is preferable that the scale-like filler has a surface direction diameter of 0.1 μm to 200 μm and an aspect ratio of 10 or more. Desirably, the diameter in the plane direction is 1 μm to 30 μm and the aspect ratio is 50 or more and 100 or less.

  The scaly filler is not limited as long as it is a flat plate or flake other than the scaly one, but graphite (graphite) is particularly preferable. As the type of graphite, either α graphite or β graphite may be used. Either natural graphite or artificial graphite may be used. In addition to graphite, graphene and the like can be mentioned. Further, graphite and graphene may be combined.

  (C) The fibrous filler preferably has a diameter of 10 nm to 30 μm, a fiber length of 1 μm to 3 mm, and an aspect ratio of 100 or more. In particular, the fibrous filler is more preferably at least one conductive fibrous filler selected from the group consisting of carbon nanofibers (CNF) and carbon nanotubes (CNT). The carbon nanotube (CNT) may be a single wall or a multiwall. Moreover, it is preferable that a carbon nanofiber (CNF) has a diameter of nanometer size and a fiber length of micrometer size.

  When the total of (a) base resin, (b) flaky filler, and (c) fibrous filler is 100% by volume, the total volume of (b) flaky filler and (c) fibrous filler is 5 to 5%. 70% by volume. Moreover, the compounding quantity of (b) scale-like filler is 1-70 volume%, Preferably it is 5-50 volume%. And the compounding quantity of (c) fibrous filler is 0.1-15 volume%, desirably 0.1-10 volume%. More desirably, it is 0.1 to 5% by volume. The upper limit of the blending amount of the fibrous filler is determined by fluidity and cost, but the effect of increasing the thermal conductivity is large even with a relatively small amount.

  Further, a dispersant may be added to increase the dispersibility of the filler. Further, as a third component, a flame retardant, a fluidity improver, a curing agent, a curing accelerator, a curing retarder, a lubricant, an antioxidant, a reinforcing filler, and the like may be added simultaneously.

  The thermally conductive resin composition of the present invention is filled with (b) scale-like filler and (c) fibrous filler, both of which have thermal conductivity in a base resin made of (a) thermosetting resin or thermoplastic resin. A plane structure in which the surfaces of one or more scale-like fillers are arranged in the same plane, and the plane structure forms one or more layer structures facing the same plane direction, and is in contact with the plane structure In the resin layer, a fibrous filler dispersion layer is formed, and the fibrous filler forms a heat conduction path between the layers. Here, when the projected area of the scale-like filler existing in the cross section cut out in parallel to the plane direction occupies 35% or more with respect to the surface area of the scale-like filler, it is defined as the same plane. Desirably, it occupies 40% or more.

  As the scale-like filler, graphite having an average particle diameter of 40 μm is used, and as the fibrous filler, carbon nanofibers (product name: VGCF-H (manufactured by Showa Denko KK)) having an average fiber diameter of 150 nm and an average fiber length of 10 μm are used. FIG. 1 shows the results of actual measurement of the thermal conductivity of the thermally conductive resin composition using an epoxy resin as a base resin. Graphite (shown as Gr in the figure) had a filling amount changed from 0 to 70% by volume, and carbon nanofibers (shown as VGCF in the figure) were fixed at 2% by volume. FIG. 2 schematically shows a cross-sectional structure of a resin molded product to which scale-like filler and fibrous filler are added. 2 (a) shows a cross section of a plane parallel to the layer structure, FIG. 2 (b) shows a cross section of a plane orthogonal to the layer structure, in which 1 is a base resin, 2 is a scaly filler, 3 is a fibrous shape The filler is shown. FIG. 3 is an image obtained by observing a cross section of a resin molded article using the heat conductive resin composition of the present invention with a scanning electron microscope (SEM).

  The solid line in FIG. 1 shows the change in thermal conductivity when only graphite is filled, and it can be seen that the thermal conductivity increases exponentially with the increase in the graphite filling amount. Sexually deteriorates. The broken line in FIG. 1 shows the change in thermal conductivity when graphite is added to a small amount of carbon nanofibers, and the thermal conductivity is significantly higher in the intermediate region (20 to 60% by volume) than in the case of graphite alone. It can be seen that it has increased. In the range with a small amount of graphite (1 to 10% by volume), the contact between the graphite is small, so that the layer structure is not sufficiently formed, and even if the layer structure is formed, the layer spacing is wide, so the heat generated by the carbon nanofibers. It is considered that the thermal conductivity is low because the conduction path is not effectively formed. On the other hand, in the range with a large amount of graphite (60 to 70% by volume), the contact between the graphites approaches the limit, and the graphite itself forms a heat conduction path, so the addition of carbon nanofibers increases the heat conductivity. It is thought that he did not contribute.

(Production method)
The heat conductive resin composition of the present invention is obtained by mixing a micron-sized scaly filler, a fibrous filler having a nano-sized diameter, and a resin. The method of kneading these is not particularly limited. For example, when mixing with a varnish-like thermosetting resin using a solvent, dispersion mixing by ultrasonic waves or planetary rotation is used. Or when mixing with a thermoplastic resin, it is preferable to knead | mix using a biaxial kneading extruder. The dispersion using ultrasonic waves here may be an ultrasonic homogenizer of about 2 kHz to 200 kHz, or an ultrasonic tank. In the above method, the order of adding the three components of the flaky filler, the fibrous filler, and the resin may be selected as appropriate, or the three components may be added simultaneously and stirred and mixed.

  The temperature during the biaxial kneading is performed at a temperature suitable for the resin used. For example, when a polypropylene resin is used, it is preferably 180 ° C. or higher and 230 ° C. or lower, more preferably 200 ° C. or higher and 220 ° C. or lower. When polyphenylene sulfide resin is used, it is preferably 280 ° C. or higher and 350 ° C. or lower. By kneading at such a temperature, the shearing force to the resin can be adjusted appropriately. In the kneading, the mixing order of the three components is not particularly limited, and may be added simultaneously or in order. In addition, fillers may be added to the molten resin, and kneading in this order can minimize mechanical loads such as shear stress applied to the scale-like filler and fibrous filler during kneading. And prevent them from being destroyed.

  As for the fibrous filler before kneading, nanofibers in a powder state (short fibers) may be used, those made into a paste state with an organic solvent, or a resin used for a heat conductive resin composition You may use the masterbatch which mixed the resin of the same kind with the nanofiber previously, and was made into the pellet.

(Heat dissipation material)
The heat dissipating material is produced by molding the heat conductive resin composition of the present invention by a molding method according to the purpose. Such a heat conductive resin composition is lightweight, has high heat conductivity, and further exhibits an excellent property of being easily dispersible because of a small amount of nanofiller. In addition to electronic devices such as semiconductor devices, casings for LED lighting, automobile headlamps and fog lamps, power modules and fuel cell modules, they can be suitably used for electronic components.

  Here, as a method for molding the heat radiation material of the present invention, for example, compression molding methods such as FRP molding and transfer molding; casting methods such as cast molding and encapsulated casting; roll processing methods such as calendar molding; RIM molding; Examples thereof include injection molding methods such as injection foam molding; foaming technology methods such as extrusion foam molding; extrusion molding methods such as inflation film molding and T-die film molding.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Examples 1-10 and Comparative Examples 1-11>
The heat conductive resin composition of each Example and each Comparative Example was obtained by the method described later with the following components having the mixing ratio shown in Table 1.
In addition, when mixing resin, a scale-like filler, and fibrous filler (nanofiber) as a structural component of a heat conductive resin composition, a fibrous filler is previously mixed with the solution which melt | dissolved resin in methyl ethyl ketone (MEK). After dispersing the fibrous filler with ultrasonic waves, the flaky filler was added and mixed with a planetary rotating stirrer. The polypropylene resin base of Example 10 was dry blended with resin, scaly filler, and fibrous filler (nanofiber), and then melt-kneaded with a biaxial kneading extruder to form a pellet.

(1) Resin (1-1) Examples 1 to 9, Comparative Examples 1 to 11;
Epoxy resin: Product name: Epicron 850 (manufactured by DIC Corporation).
Curing agent: acid anhydride EPICLON B-570H (manufactured by DIC Corporation).
Resin and curing agent were added in equivalent amounts.
(1-2) Example 10;
Polypropylene: Prime Polypro BJS-MU (manufactured by Prime Polymer Co., Ltd.).
(2) Scale-like filler Graphite: CB150, average particle diameter of 40 μm (manufactured by Nippon Graphite Co., Ltd.).
(3) Fibrous filler (3-1) Nanofiber CNF: Carbon nanofiber having an average fiber diameter of 150 nm and an average fiber length of 10 μm (product name: VGCF-H (manufactured by Showa Denko KK)).
(3-2) Carbon fiber Carbon fiber: Pitch-based carbon fiber having an average fiber diameter of 11 μm and an average fiber length of 6 mm (product name: DIALEAD K6371T (manufactured by Mitsubishi Plastics)).
(4) Spherical filler Spheroidized graphite: CGC-50 Average particle diameter of 50 μm (manufactured by Nippon Graphite Co., Ltd.).

  The heat conductive resin composition of each Example and each comparative example was produced by performing dispersion | distribution by these ultrasonic waves, and mixing with a planetary rotary stirrer or a biaxial kneading extruder. Next, this was press-molded at a face plate temperature of 180 ° C. at a predetermined pressure to obtain a sheet-like material. The projected area of the flaky filler present in the cross-section cut out in the plane direction of the obtained sheet-like material is 35% or more with respect to the surface area of the flaky filler in both Examples and Comparative Examples using graphite. Met.

(Characteristic evaluation)
In order to evaluate the thermal conductivity of the thermally conductive resin compositions of the Examples and Comparative Examples obtained above, the sheet-like material was cut and processed to be a 10.0 mm × 10.0 mm × 1 mm thick test piece. Prepared. The density, specific heat, thermal diffusivity and thermal conductivity of this test piece were measured by the following methods, respectively. The results are shown in Table 1 below.

(density)
The measurement was carried out at room temperature (25 ° C.) by the water displacement method.

(specific heat)
Measuring method: Differential scanning calorimetry (DSC).
Measuring device: Input-compensated differential scanning calorimeter (device name: DSC6220 (SII Nanotechnology)).
Temperature increase rate: 10 ° C./min.
Sample amount: 10 mg.

(Thermal diffusivity)
Measuring method: Laser flash method.
Measuring device: Thermophysical property measuring device (Product name: TC-7000 (ULVAC Riko)).
Measurement direction: Measures the thermal diffusivity in the in-plane direction.

(Thermal conductivity)
The thermal conductivity was calculated by substituting each value of the density, specific heat, and thermal diffusivity obtained above into the following equations. In addition, it is excellent in heat dissipation, so that the value of this heat conductivity is high.
Thermal conductivity (W / m · K) = density (kg / m ³ ) × specific heat (kJ / kg · K) × thermal diffusivity (m ² / s) × 1000 (kJ / J)

(Evaluation results and discussion)
In Table 1, for example, when comparing Examples 1 to 4 and Comparative Examples 1 to 4, even if the graphite filling amount is the same, by adding a small amount of carbon nanofibers (CNF) of at most 1% by volume, It can be seen that the thermal conductivity in the in-plane direction of the thermally conductive resin composition is greatly increased. For example, the thermal conductivity of Example 3 (35% by volume of graphite, 0.5% by volume of VGCF) is 31 W / m · K, whereas the thermal conductivity of Comparative Example 3 (35% by volume of graphite) is 18 W / m. m · K. That is, the effect of adding a small amount of fibrous filler to the scaly filler is obvious.

  The reason for this is that in Examples 1 to 4, by using a scaly filler and a fibrous filler in combination, a heat conduction path is efficiently formed with a fibrous filler between the layer structures formed by the scaly filler. Whereas the thermal conductivity could be increased, in Comparative Example 2, only the layer structure of scaly filler was formed, the base resin layer was present between the layers, and the heat transfer path was not sufficiently formed. It is considered that the conductivity could not be increased.

  In Comparative Examples 6 to 9, in contrast to Examples 1 to 3, Example 4 (graphite 50 volume%, VGCF 0.5 volume%) was obtained when a fibrous filler having a different shape was blended with the scale-like filler graphite. The thermal conductivity of 53 W / m · K is 25.4 W / m · K in Comparative Example 9 (CF 50 vol%, VGCF 0.5 vol%), and the amount of filling is as small as 30%. It was revealed that the thermal conductive resin composition of Example 3 (35% by volume of graphite and 0.5% by volume of VGCF) using a filler exhibits superior thermal conductivity.

  This is because the carbon fiber (CF) of Comparative Example 9 is in contact with the nanofibers with a line, whereas in Example 4, a scale-like filler is used to efficiently form a layer in the resin, and the nanofibers It is considered that the thermal conductivity can be increased by making it easier to form a heat conduction path by contacting the surface.

  Moreover, when Example 8 and Example 9 are compared, the filling amount of graphite is the same as 20% by volume, and the filling amount of carbon nanofiber (CNF) is 5% by volume in Example 8 and 15% by Example 9. It can be seen that the thermal conductivity does not increase so much at 25 W / m · K in Example 8 and 28 W / m · K in Example 9 despite the fact that it is increased by 3 times. Therefore, to increase the thermal conductivity, it is most effective to add a small amount of carbon nanofiber (CNF) after increasing the graphite filling amount rather than increasing the carbon nanofiber (CNF) filling amount. Is.

  In addition, comparing Example 3 and Example 10, whether the base resin is an epoxy resin or a polypropylene resin is substantially the same as long as the filling amount of graphite and carbon nanofiber (CNF) is the same. It shows that thermal conductivity can be obtained.

  Moreover, when Example 3 and Comparative Example 11 are compared, when the scaly graphite is spheroidized graphite, the effect of increasing the thermal conductivity by the carbon nanofibers cannot be obtained even if the filling amount is the same. Is shown.

  From the above results, the thermally conductive resin composition of the present invention is a case where only graphite or carbon fiber is used as a material exhibiting thermal conductivity by using a scaly filler and a fibrous filler (nanofiber) in combination. As compared with the case of using nanofiber with nanofiber, it has been clarified that the heat conductivity is very high.

Although the embodiments and examples of the present invention have been described above, the configurations of the above-described embodiments and examples can be appropriately combined.
The embodiments and examples disclosed herein are illustrative and non-restrictive in every respect, and the scope of the present invention is indicated by the scope of the claims, rather than the description above, and the scope of the claims It is intended that all changes within the meaning and scope equivalent to are included.

1 Base resin 2 Scale-like filler 3 Fibrous filler

And when filled with only graphite epoxy resin is a graph showing the change in thermal conductivity for graphite-filled volume, when filled by adding the carbon nanofibers 2% by volume of graphite. 1 schematically shows a cross-sectional structure of a molded article using the heat conductive resin composition of the present invention, in which (a) is a cross section of a plane parallel to the layer structure, and (b) is a plane orthogonal to the layer structure. A cross section is shown. It is a cross-sectional SEM image of the molded article using the heat conductive resin composition of this invention.

The thermally conductive resin composition of the present invention is filled with (b) scale-like filler and (c) fibrous filler, both of which have thermal conductivity in a base resin made of (a) thermosetting resin or thermoplastic resin. A plane structure in which the surfaces of one or more scale-like fillers are arranged in the same plane, and the plane structure forms one or more layer structures facing the same plane direction, and is in contact with the plane structure In the resin layer, a fibrous filler dispersion layer is formed, and the fibrous filler forms a heat conduction path between the layers. Here, when the projected area of the scale-like filler existing in the cross section cut out in parallel to the plane direction occupies 35% or more with respect to the surface area of the scale-like filler, it is defined as the same plane. Desirably, it occupies 40% or more .

The solid line in FIG. 1 shows the change in thermal conductivity when only graphite is filled, and it can be seen that the thermal conductivity increases exponentially with the increase in the graphite filling amount. Sexually deteriorates. The broken line in FIG. 1 shows the change in thermal conductivity when a small amount of carbon nanofibers is added to graphite, and the thermal conductivity is significantly higher in the intermediate region (20 to 60% by volume) than in the case of graphite alone. It can be seen that it has increased. In the range with a small amount of graphite (1 to 10% by volume), the contact between the graphite is small, so that the layer structure is not sufficiently formed, and even if the layer structure is formed, the layer spacing is wide, so the heat generated by the carbon nanofibers. It is considered that the thermal conductivity is low because the conduction path is not effectively formed. On the other hand, in the range with a large amount of graphite (60 to 70% by volume), the contact between the graphites approaches the limit, and the graphite itself forms a heat conduction path, so the addition of carbon nanofibers increases the heat conductivity. It is thought that he did not contribute.

Claims (7)

  (A) A base resin made of a thermosetting resin or a thermoplastic resin is filled with (b) scaly filler and (c) fibrous filler, both of which have thermal conductivity, and the surface of one or more scaly fillers Form a planar structure in which the planar structures are aligned in the same plane, the planar structure forms one or more layered structures facing the same planar direction, and a dispersed layer of fibrous filler is formed in the resin layer in contact with the planar structure. A thermally conductive resin composition, wherein the fibrous filler is formed by forming a thermal conduction path between layers.   When the total of (a) base resin, (b) flaky filler, and (c) fibrous filler is 100% by volume, the total volume of (b) flaky filler and (c) fibrous filler is 5 to 5%. The heat conductive resin composition which is a conductive fiber according to claim 1, which is 70% by volume.   (C) The thermally conductive resin composition according to claim 1 or 2, wherein the fibrous filler has a diameter of 10 nm to 30 µm, a fiber length of 1 µm to 3 mm, and an aspect ratio of 100 or more.   The heat according to any one of claims 1 to 3, wherein (c) the fibrous filler is at least one conductive fibrous filler selected from the group consisting of carbon nanofibers (CNF) and carbon nanotubes (CNT). Conductive resin composition.   When the total of (a) base resin, (b) scale-like filler, and (c) fibrous filler is 100% by volume, (c) the amount of fibrous filler is 0.1 to 15% by volume. Item 5. The thermal conductive resin composition according to any one of Items 1 to 4.   (B) The diameter of the scale-like filler in the surface direction is 0.1 μm to 200 μm and the aspect ratio is 10 or more. The heat conductive resin composition according to claim 1.   (B) The scaly filler is one or more conductive scaly fillers selected from the group consisting of graphite and graphene. The heat conductive resin composition according to any one of claims 1 to 6.