JP2012072363A - Heat-conductive resin composition and heat-radiating material comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-conductive resin composition which is lightweight and also has high heat conductivity.SOLUTION: The heat-conductive resin composition includes: flaky metal powder; a fibrous carbon material; and a resin. Preferably, the heat-conductive resin composition includes: 10 to 60 mass% of flaky metal powder; 2 to 20 mass% of a fibrous carbon material; and 20 to 88 mass% of a resin. More preferably, the heat-conductive resin composition includes: 10 to 40 mass% of flaky metal powder; 2 to 20 mass% of a fibrous carbon material; and 40 to 88 mass% of a resin.

Description

  The present invention relates to a heat conductive resin composition and a heat dissipation material including the same, and more particularly to a heat conductive resin composition including a flaky metal powder, a fibrous carbon material, and a resin, and a heat dissipation material including the same.

  In recent years, energy-saving and environment-friendly products have been developed. For example, LED lighting is employed in lighting equipment mounted on automobiles, and solar cells are employed as energy sources to replace petroleum energy.

  However, LED lighting has a problem in that the life of the LED itself is extremely shortened due to heat generated from the LED package. Therefore, an LED package capable of efficiently dissipating heat is required. Similarly, in solar cells, heat generated from devices is a problem, and it is said that it is necessary to take measures for heat dissipation.

  In addition, in a semiconductor element such as a semiconductor device or an IC, internal circuits are highly integrated in order to reduce the size of the semiconductor element itself. Along with this, the amount of heat generation per unit volume is increasing, and how to efficiently dissipate this heat generation to the outside is a problem. Incidentally, the semiconductor element is protected from the outside by being wrapped in a package.

  Conventionally, ceramics having excellent heat dissipation have been used as a package material in order to enhance the heat dissipation of a semiconductor element. However, in recent years, in response to demands for reducing material costs, the packaging material has been replaced with ceramics, such as epoxy resins and silicone resins. However, if the package material is composed only of resin, there is a problem that the heat dissipation of the package itself is extremely low. Therefore, a material obtained by adding an inorganic substance having high thermal conductivity to the resin is actually used. Below, what added various components, such as an inorganic substance, to resin is described as "resin composition", and especially what shows thermal conductivity among them is described as "thermal conductive resin composition."

  As the inorganic material, silica, alumina, boron nitride (BN), metal powder, or the like can be used. By appropriately selecting the composition and the amount of addition from these inorganic materials, the thermal conductivity of the resin composition is adjusted to improve the heat dissipation. However, among the above inorganic materials, alumina has a drawback that the mold is worn during molding, and BN itself is expensive. For this reason, silica is generally preferably used as the inorganic material, and in particular, crystalline silica having a high thermal conductivity is often used.

  Japanese Patent Laid-Open No. 05-086246 (hereinafter also referred to as “Patent Document 1”) discloses a heat conductive resin composition containing a metal powder having high heat conductivity as an inorganic substance. Japanese Patent Laid-Open No. 2006-321968 (hereinafter also referred to as “Patent Document 2”) discloses a composite material composition containing carbon nanotubes having high thermal conductivity as an inorganic substance and further using ceramics. ing. Such carbon nanotubes have a high thermal conductivity of about 400 W / (m · K) or more and 1200 W / (m · K) or less, and therefore exhibit excellent performance as an inorganic substance for improving thermal conductivity.

JP 05-086246 A JP 2006-321968 A

  However, since the metal powder disclosed in Patent Document 1 has a spherical shape, the thermal conductivity cannot be sufficiently improved only by adding a small amount thereof to the resin. If a large amount of spherical metal powder is added to obtain thermal conductivity as in Patent Document 1, the weight of the resin composition itself becomes heavy, making it unsuitable for a semiconductor device package.

  Further, in Patent Document 1, graphite is added, but this is added for the purpose of improving the slidability of the heat conductive resin composition, so that Example 14 in Table 2 of Patent Document 1 is used. As is apparent from the thermal conductivity values of Comparative Example 6, no effect is exerted on the improvement of thermal conductivity.

  On the other hand, as in the composite material composition disclosed in Patent Document 2, the thermal conductivity can be increased by containing a large amount of carbon nanotubes. However, since carbon nanotubes are poor in handling properties, filling them in a large amount in the resin results in poor fluidity and poor processability, and even if processed, there is a disadvantage that the mechanical strength decreases. is expected. In addition, since the carbon nanotubes themselves are very expensive materials, there is a problem in terms of material cost to use a large amount of them.

  The present invention has been made in view of the current situation as described above, and an object of the present invention is to provide a thermally conductive resin composition that is lightweight and has high thermal conductivity.

  As a result of intensive studies to solve the above problems, the present inventors have found that metal powders, particularly flakes, contribute significantly to improving thermal conductivity. Based on these findings, further studies have been conducted, and by coexisting carbon nanotubes and flaky metal powder in the resin, the content of carbon nanotubes can be extremely reduced, and the heat conduction of the resin composition can be reduced. It has been found that the property can be remarkably improved. Furthermore, the present inventors have found that the same effect of improving thermal conductivity can be obtained with fibrous carbon materials other than carbon nanotubes, and the present invention has been completed.

  That is, the thermally conductive resin composition of the present invention is characterized by containing flaky metal powder, a fibrous carbon material, and a resin. Said heat conductive resin composition is 10 mass% or more and 60 mass% or less flaky metal powder, 2 mass% or more and 20 mass% or less fibrous carbon material, and 20 mass% or more and 88 mass% or less resin. 10 mass% or more and 40 mass% or less flaky metal powder, 2 mass% or more and 20 mass% or less fibrous carbon material, and 40 mass% or more and 88 mass% or less resin. It is more preferable.

  The fibrous carbon material is preferably a carbon nanotube. The fibrous carbon material preferably has an average fiber diameter of 3 nm to 500 nm and an average fiber length of 0.5 nm to 20 μm.

  The flaky metal powder has an average particle diameter of 1 μm to 100 μm, an average thickness of 0.01 μm to 5 μm, and an aspect ratio of 5 to 1000, preferably aluminum. It is more preferable. Moreover, this invention is also a heat radiating material containing said heat conductive resin composition.

  The heat conductive resin composition of the present invention has an excellent effect of having very high heat conductivity and being lightweight by having the above-described configuration. And since the fibrous carbon material is mixed with the flaky metal powder, the heat conductive resin composition of this invention can improve fluidity | liquidity.

It is an image when the cross section of the heat conductive resin composition of this invention is observed by 500 time magnification by SEM. It is an image when the cross section of the heat conductive resin composition of this invention is observed by 2000 times with SEM. It is a figure which shows typically the sheet-like material for evaluating the heat conductivity of a heat conductive resin composition.

Hereinafter, the thermally conductive resin composition of the present invention will be described.
<Thermal conductive resin composition>
The thermally conductive resin composition of the present invention is characterized by containing flaky metal powder, a fibrous carbon material, and a resin. As described above, the present invention is characterized in that the resin includes the flaky metal powder and the fibrous carbon material. As a result, a large amount of the fibrous carbon material that has been conventionally used can be greatly reduced and the thermal conductivity can be remarkably increased.

  That is, by mixing the flaky metal powder and the fibrous carbon material with the resin, the content of the fibrous carbon material is reduced as compared with the case where the fibrous carbon material is mixed with the resin alone, and thus the heat is increased. The fluidity of the conductive resin composition is improved.

  Further, the heat conductive resin composition of the present invention is very high compared to the case where only metal powder is used as a material exhibiting heat conductivity as in the prior art, or when a carbon material and ceramics are used in combination. It exhibits thermal conductivity and is lighter than when only metal powder is used as a material exhibiting thermal conductivity.

  Although the cause of the remarkable increase in thermal conductivity by coexisting the fibrous carbon material and the flaky metal powder in the resin is not clear, the dispersibility of the flaky metal powder in the resin is probably not clear. As a result, the flaky metal powder is arranged in parallel in a layered manner in the flow direction of the resin, and the fibrous carbon material is dispersed so as to connect the layers, so that the heat conductive resin composition is heated. This is presumably due to the formation of a conductive network.

  Such inference is derived on the basis of an image obtained by observing a cross section of the heat conductive resin composition of the present invention with a scanning electron microscope (SEM). That is, both FIG. 1 and FIG. 2 are images obtained by observing the cross section of the thermally conductive resin composition of the present invention with an SEM (FIG. 1 is a 500 times magnification and FIG. 2 is a 2000 times observation image). From the image, the flaky metal powder is uniformly dispersed in parallel in a layer form in the resin, and the distance between the layers of the flaky metal powder is relatively close to the average fiber length of the fibrous carbon material. I can confirm that. 1 and 2 are both cross-sectional views of the thermally conductive resin composition of Example 1 described later.

  The content ratio of the three components is 10 mass% or more and 60 mass% or less of flaky metal powder, 2 mass% or more and 20 mass% or less of fibrous carbon material, and 20 mass% or more and 88 mass% or less of resin. It is preferable to contain, More preferably, it is 10 mass% or more and 40 mass% or less flaky metal powder, 2 mass% or more and 20 mass% or less fibrous carbon material, and 40 mass% or more and 88 mass% or less resin. Is to include. By setting such a content ratio, even when the flaky metal powder is added at a high concentration, high thermal conductivity can be exhibited without deteriorating kneadability.

  In addition, in addition to the said 3 component, a heat conductive resin composition may add a small amount of hardening | curing materials, a hardening accelerator, a coloring material, etc. in some cases. Hereinafter, each component contained in the heat conductive resin composition of this invention is demonstrated.

<Fibrous carbon material>
The fibrous carbon material used for this invention will not be specifically limited if it is excellent in heat conductivity, A conventionally well-known thing can be used. Such a fibrous carbon material is preferably contained in the thermally conductive resin composition at a mass ratio of 2% by mass or more and 20% by mass or less, and is contained at a mass ratio of 8% by mass or more and 15% by mass or less. Is more preferable. By filling the fibrous carbon material at such a ratio, since the handling property is good, the kneading property is excellent, and a high thermal conductivity can be expressed. When the mass ratio of the fibrous carbon material exceeds 20% by mass, it is disadvantageous in terms of cost performance.

  Further, as the fibrous carbon material used in the present invention, at least one selected from the group consisting of vapor grown carbon fiber, carbon nanotube, pitch-based carbon fiber, and PAN (PolyAcryloNitrile) -based carbon fiber should be used. Is preferred. Among them, it is preferable to use a fibrous carbon material excellent in thermal conductivity, and it is more preferable to use a carbon nanotube having high thermal conductivity.

  The fibrous carbon material is preferably a fibrous material having an average fiber diameter of 3 nm to 500 nm and an average fiber length of 0.5 μm to 20 μm. More preferably, the fiber has an average fiber diameter of 10 nm to 100 nm and an average fiber length of 8 μm to 12 μm. By using a fibrous carbon material that satisfies the numerical ranges of the average fiber diameter and the average fiber length, it is considered that the above-described heat conduction network can be easily formed and the heat conductivity can be increased.

  Here, the average fiber diameter and the average fiber length of the above-described fibrous carbon material are the values of 100 fibers arbitrarily selected when the fibrous carbon material is observed using a scanning electron microscope (SEM). It is an average value of fiber diameter (diameter) and fiber length (major diameter).

  When using commercially available carbon nanotubes as the above-mentioned fibrous carbon material, for example, VGCF series from Showa Denko KK (VGCF: average fiber diameter 150 nm and average fiber length 8 μm, VGCF-H: average fiber diameter 150 nm and average fiber length 6 μm, In addition to VGCF-S: average fiber diameter of 80 nm and average fiber length of 10 μm, VGCF-X: average fiber diameter of 15 nm and average fiber length of 3 μm, MWNT (Multi Wall carbon Nano Tube, average fiber diameter manufactured by Hyperion Catalysis International) 10 nm and an average fiber length of around 1 μm), Nanocyl 7000 series (average fiber diameter of 9.5 nm and average fiber length of 1.5 μm) manufactured by Belgian Nanoseal Co., Ltd. can be used.

<Flake metal powder>
The flaky metal powder used in the present invention is preferably contained in a mass ratio of 10% by mass to 60% by mass, more preferably 15% by mass to 30% by mass. Such a flaky metal powder may be composed of only a metal or a metal-based alloy. The metal can be used without particular limitation as long as it is a metal having thermal conductivity, but one or more selected from the group consisting of aluminum, copper, silver, iron, nickel, silicon, zinc, and tin It is preferable to use a metal or an alloy of the metal. Among these, aluminum is preferably used from the viewpoint of thermal conductivity, electrical insulation, light weight, and cost balance. Any purity of these metals can be used without any particular limitation.

  The average particle size of the flaky metal powder used in the present invention is not particularly limited, but is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 30 μm or less. By using a material having an average particle diameter within the above range, there is an advantage that the moldability and appearance of the heat conductive resin composition are excellent. Here, as the average particle size of the flaky metal particles, a value obtained by calculating the volume average based on the particle size distribution measured by the laser diffraction method is adopted.

The average thickness of the flaky metal powder is not particularly limited, but is preferably 0.01 μm or more and 5 μm or less, more preferably 0.03 μm or more and 1 μm or less. The flaky metal powder having such an average thickness has an advantage of improving the moldability and appearance of the heat conductive resin composition. On the other hand, if it is less than 0.01 μm, the moldability of the thermally conductive resin composition may be lowered, and if it exceeds 5 μm, there is a problem that the flaky metal powder protrudes to deteriorate the appearance. Here, the average thickness (μm) of the flaky metal powder is calculated from the following formula by measuring the water surface diffusion area (WCA) per 1 g of the flaky metal powder.
Formula: Average thickness (μm) = 0.4 (m ² · μm · g ⁻¹ ) / WCA (m ² · g ⁻¹ )
In addition, the said water surface diffusion area (WCA) shall employ | adopt the value measured by the method described in JISK5906: 1998 Aluminum pigment for coating materials.

  The flaky metal powder used in the present invention preferably has a shape factor (hereinafter referred to as “aspect ratio”) obtained by dividing the average particle diameter by the average thickness of 5 to 1000, preferably 50 to 500. More preferably, it is 10 or more and 200 or less. By using the flaky metal powder having such an aspect ratio, the effect of improving the thermal conductivity becomes more remarkable.

  Note that the flaky metal powder may be produced by any manufacturing method, but from the viewpoint that the metal powder can be easily flaked, produced by a wet pulverization method using a ball mill or the like. It is preferable to use those prepared.

  When flaking using a wet pulverization method, the pulverization aid used for pulverization may adhere to the surface of the flaky metal powder. Here, the grinding aid is not particularly limited, and any conventionally known one can be used. For example, fatty acids such as oleic acid and stearic acid, aliphatic amines, aliphatic amides, aliphatic Alcohols, ester compounds and the like can be suitably used.

<Resin>
The heat conductive resin composition of the present invention is characterized by containing 20% by mass or more and 88% by mass or less of resin, and preferably contains 50% by mass or more and 88% by mass or less of resin. By including the resin at such a ratio, the molding fluidity of the heat conductive resin composition is hardly impaired, and thus the molding can be easily molded. Furthermore, the content of the resin is more preferably 50% by mass or more and 88% by mass or less. Thereby, there exists a merit that the practical mechanical physical property of a heat conductive resin composition is also hold | maintained.

  In the present invention, the resin may be appropriately selected according to various performances required by the heat conductive resin composition, and is particularly preferably selected according to the performance required by the heat dissipation material. Moreover, the heat conductive resin composition of this invention may be comprised only with single resin, and may use 2 or more types of resin together. As such a resin, a thermosetting resin may be used, a thermoplastic resin may be used, or these may be used in combination. Among them, the thermoplastic resin can be molded in various forms by hot melt molding by molding methods such as injection, hollow, extrusion, and vacuum, and can be easily recycled (recycled). This is preferable because there are merits such as possible.

  As said thermosetting resin, unsaturated polyester resin, an epoxy resin, a urethane resin etc. other than amino resins, such as a phenol resin, a urea resin, a melamine resin, can be used, for example. As the thermoplastic resin, for example, ABS resin, polycarbonate resin, polyester resin, vinyl chloride resin, acrylic resin polyamide resin, polyacetal resin, etc. can be used in addition to polyolefin resin such as polypropylene resin.

  Among the above thermoplastic resins, polypropylene resin is a resin that is used for general purposes and has an advantage of excellent heat resistance. ABS resin, polycarbonate resin, and the like are non-required in the field of precision molding technology. It is preferable because it has excellent dimensional stability peculiar to crystalline polymers and has a great track record in electronic parts.

<Other ingredients>
The heat conductive resin composition of the present invention may contain other components in addition to the above three components as long as the effects of the present invention are not affected. Examples of other components include thermally conductive materials such as aluminum nitride, silicon nitride, boron nitride, and aluminum oxide, and additives such as lubricants, antioxidants, and pigments.

<The manufacturing method of a heat conductive resin composition>
The heat conductive resin composition of the present invention is obtained by kneading a flaky metal powder, a fibrous carbon material, and a resin. The method for kneading these three components is not particularly limited. For example, it is preferable to knead using a single-screw or twin-screw kneading extruder or kneading using a kneader kneader.

  The kneading apparatus used for the kneading here may be an open type provided with a vent port, or may be a sealed type with a vacuum degassing device or the like. Further, the above three components may be kneaded and subsequently molded by an injection molding machine. In this case, the raw materials of the above three components are mixed and charged as they are into an injection molding machine and molded in a dry blend state.

  In addition, since the optimum temperature varies depending on the resin to be used, it is difficult to uniquely define a numerical range, but for example, when a polypropylene resin is used as the resin, the temperature during kneading is 180 ° C. or higher and 230 ° C. or lower. It is preferable that it is 200 degreeC or more and 220 degrees C or less more preferably. By kneading within such a temperature range, the flaky metal powder and the fibrous carbon material can be prevented from being cut or broken by a mechanical load such as a shearing action during kneading.

  The kneading time when kneading using a kneader-type kneader is not particularly limited, but is preferably 3 minutes or longer and 20 minutes or shorter, more preferably 5 minutes or longer and 15 minutes or shorter. By kneading within such a range, it is possible to suppress the flaky metal powder and the fibrous carbon material from being cut or destroyed by the mechanical load during kneading and to disperse uniformly. You can also.

  In the kneading, the mixing order of the above three components is not particularly limited and may be added at the same time or may be added in order, but after the resin is first added and completely melted. It is preferable to add and knead the flaky metal powder and the fibrous carbon material. By kneading in this order, mechanical loads such as shear stress applied to the flaky metal powder and fibrous carbon material during kneading can be minimized, and they are prevented from being cut or broken. can do.

  Moreover, as a flaky metal powder before kneading | mixing, the thing of a powder state may be used and what was made into the paste state with non-volatile solvents, such as a mineral spirit, may be used. Moreover, you may use the masterbatch which mixed the flake shaped metal powder with thermoplastic resins, such as a polyethylene resin, and various waxes, such as a polyethylene wax, and made into the pellet form. Among these, it is preferable to introduce the flaky metal powder by a masterbatch from the viewpoint of easy handling and easy mixing with a resin.

  The same applies to the fibrous carbon material before kneading, and a fibrous carbon material in a powder state may be used, a paste made with an organic solvent may be used, or a thermally conductive resin composition may be used. A master batch in which the same type of resin as the resin to be used is mixed with the fibrous carbon material in a pellet state may be used. Among these, it is preferable to introduce the fibrous carbon material by a masterbatch from the viewpoint of easy handling and easy mixing with a resin.

<Heat dissipation material>
The heat dissipation material of this invention is characterized by including said heat conductive resin composition. Such a heat dissipation material is produced by molding a heat conductive resin composition by a molding method according to the purpose. Such a heat conductive resin composition is lightweight and exhibits excellent properties such as high heat conductivity. Therefore, the heat dissipating material formed thereby can be used for semiconductor devices, LED lighting casings, solar cell modules, and the like. It can be suitably used for electronic components as well as electronic devices.

  Here, as a method of 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; firing technique 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 to 10 and Comparative Examples 1 to 7>
The heat conductive resin composition of each Example and each Comparative Example was obtained by the method described later with the components shown in the following (1) to (5) having the mixing ratio shown in Table 1 below. Is.

  In addition, in mixing a fibrous carbon material as a structural component of a heat conductive resin composition, after preparing the masterbatch containing a fibrous carbon material and resin previously, it mixed with the other component. Specifically, the same resin (PP) as the resin shown in the following (2) which is a component to be mixed with the heat conductive resin composition to be obtained so that the fibrous carbon material in the masterbatch is 20% by mass. This is a master batch obtained by mixing PP resin) and a fibrous carbon material.

Moreover, when mixing flaky aluminum powder as a structural component of a heat conductive resin composition, it mixed with the other component using what was made into the masterbatch by mixing the said flaky aluminum powder with resin etc. Specifically, a masterbatch obtained by mixing polyethylene resin (PP resin), polyethylene wax and flaky aluminum powder so that the flaky aluminum powder in the masterbatch becomes 70% by mass (product name: Metax Neo (Toyo Aluminum Co., Ltd.) was used.
(1) Fibrous carbon material CNT: Carbon nanotube with an average fiber diameter of 80 nm and an average fiber length of 10 μm (product name: VGCF-S (manufactured by Showa Denko KK))
Carbon fiber: Carbon fiber having an average fiber diameter of 8 μm and an average fiber length of 6 mm (product name: Tenax HTA-C6-US (manufactured by Toho Tenax Co., Ltd.))
(2) Resin PP resin: (Product name: Injection molding grade Sumitomo Noblen Z101A (manufactured by Sumitomo Chemical Co., Ltd.))
ABS resin: (Product name: Injection molding grade Ceviane-V660SF (manufactured by Daicel Polymer Co., Ltd.))
(3) Flaky metal powder Flaky aluminum powder having an average particle diameter of 18 μm and average thickness of 0.4 μm (4) Spherical metal powder Spherical aluminum powder obtained by an atomizing method having an average particle diameter of 20 μm (5) Ceramic powder Al ₂ O ₃ (Product name: AS10 (made by Showa Denko KK))
And each example and each comparison by kneading these on the conditions shown in the following Table 2 using a closed mixer (product name: Labo Plast Mill 100C 100 type (Toyo Seiki Seisakusho Co., Ltd.)). The example heat conductive resin composition was produced. Next, this was press-molded under the conditions shown in Table 3 to obtain a sheet.

<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 a test piece having a thickness of 5.0 mmΦ × 1.0 mmt was obtained. Prepared (see FIG. 3). The density, specific heat, thermal diffusivity, thermal conductivity, and flow value of this test piece were measured by the following methods. The results are shown in Table 4 below.

(density)
The measurement was performed at room temperature (20 ° C.) by an underwater substitution method.

(specific heat)
Measuring method: Differential scanning calorimetry (DSC)
Measuring device: Input compensation differential scanning calorimeter (device name: Pyris Diamond DSC (manufactured by PerkinElmer Japan))
Temperature increase rate: 20 ° C / min
Sample amount: 15mg
Atmosphere: Helium 20mL / min
(Thermal diffusivity)
Measuring method: Laser flash method Measuring device: Thermophysical property measuring device (Product name: LFA-502 (manufactured by Kyoto Electronics Industry Co., Ltd.))
Analysis method: curve fitting method Atmosphere: nitrogen 20 mL / min
Measurement direction: The thermal diffusivity in the thickness direction and in-plane direction was measured for the test piece having the shape shown in FIG. 3, and the measurement results are shown in Table 4.

(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 shows that it is excellent in thermal conductivity (namely, 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)
(Flow value)
Measurement method: Conforms to JIS K7210: 1999 Annex C Tester: Flow tester CFT-500 type (manufactured by Shimadzu Corporation)
Test temperature: 250 ° C
Preheating time: 5 minutes Sample: 1.5 g
Die: 1.0Φ × 1.0mm
Plunger area: 1 cm ²
Load: 0.88kN (90kgf) (flow value measurement)
The flow value obtained under such conditions indicates the fluidity of the thermally conductive resin composition, and the higher the flow value, the higher the fluidity.

<Evaluation results and discussion>
In Table 4, for example, when comparing Example 5 and Comparative Example 2, the thermal conductivity in the in-plane direction of the thermally conductive resin composition of Example 5 is 2.85 W / m · K, In Comparative Example 2, it was 2.5 W / m · K. From this, it was clarified that the heat conductive resin composition of Example 5 showed excellent heat conductivity as compared with that of Comparative Example 2.

  The reason for this is that in Example 5, the thermal conductivity was increased by using carbon nanotubes and flaky metal particles in combination, whereas in Comparative Example 2, a large amount of ceramic powder was added. This is thought to be due to the increased thermal conductivity.

The flow value of the heat conductive resin composition of Example 5 was 1.5 cm ³ / s, whereas that of Comparative Example 2 was 0.069 cm ³ / s. From this, it became clear that the heat conductive resin composition of Example 5 showed excellent fluidity compared with that of Comparative Example 2.

  The reason for this is that in Example 5, the fluidity was improved by reducing the amount of carbon nanotubes with the addition of the flaky metal powder, whereas in Comparative Example 2, the ceramic powder was improved. This is considered to be because the fluidity was remarkably lowered by adding a large amount of. Here, in Example 5, the reason why the fluidity of the thermally conductive resin composition was improved was that the flake-shaped metal powder was used in Example 5, so that it was dispersed so as to be oriented in the resin flow direction. This is also considered as a factor.

Furthermore, the density of the thermally conductive resin composition of Example 5 was 1.07 × 10 ³ kg / m ³ , whereas that of Comparative Example 2 was 2.19 × 10 ³ kg / m ³ . there were. From this, it became clear that the heat conductive resin composition of Example 5 was lighter than that of Comparative Example 2. The reason for this is considered to be that in Comparative Example 2, a large amount of ceramic powder was blended.

  The relationship between Example 5 and Comparative Example 2 as described above can be said to be the same in the comparison between Examples 1 and 2 and Comparative Example 3. That is, in Examples 1 and 2, the carbon nanotubes and the flaky metal particles are used in combination to increase the thermal conductivity and show good fluidity. In Comparative Example 3, the flaky aluminum powder is Since the thermal conductivity is increased by blending in a large amount, the density is high, sufficient thermal conductivity cannot be obtained, and the fluidity is deteriorated.

  As a result of the comparison between the examples and the comparative examples as described above, the thermal conductive resin compositions of the examples are lighter than the corresponding comparative examples, and have good fluidity and high thermal conductivity. It became clear that there was a tendency to show.

  From the above results, the thermally conductive resin composition of the present invention contains a fibrous carbon material and a flaky metal powder in combination as a material exhibiting thermal conductivity. As compared with the case where the carbonaceous material and the ceramic were used in combination, it was revealed that the heat conductivity was very high. Moreover, it was shown that it becomes a heat conductive resin composition which is lightweight and has high heat conductivity as compared with the case where only metal powder is used as a material exhibiting heat conductivity.

  Furthermore, by mixing the fibrous carbon material with the resin together with the flaky metal powder, the fluidity of the thermally conductive resin composition is better than when the fibrous carbon material is mixed with the resin alone. It was shown to be.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (8)

  A thermally conductive resin composition comprising a flaky metal powder, a fibrous carbon material, and a resin.   The flaky metal powder in an amount of 10% to 60% by mass, the fibrous carbon material in an amount of 2% to 20% by mass, and the resin in an amount of 20% to 88% by mass. The thermally conductive resin composition described in 1.   The flaky metal powder in an amount of 10 to 40% by mass, the fibrous carbon material in an amount of 2 to 20% by mass, and the resin in an amount of 40 to 88% by mass. Or the heat conductive resin composition of 2.   The thermally conductive resin composition according to claim 1, wherein the fibrous carbon material is a carbon nanotube.   The thermally conductive resin composition according to any one of claims 1 to 4, wherein the fibrous carbon material has an average fiber diameter of 3 nm to 500 nm and an average fiber length of 0.5 nm to 20 µm. .   The flaky metal powder has an average particle diameter of 1 μm or more and 100 μm or less, an average thickness of 0.01 μm or more and 5 μm or less, and an aspect ratio of 5 or more and 1000 or less. A thermally conductive resin composition according to claim 1.   The thermally conductive resin composition according to claim 1, wherein the flaky metal powder is aluminum.   A heat dissipating material comprising the thermally conductive resin composition according to claim 1.