JP5229462B2 - Insulating high thermal conductivity resin composite material - Google Patents

Description

  The present invention relates to an insulating high thermal conductivity resin composite material.

  In the electric and electronic fields, not only high performance of personal computers but also household appliances such as refrigerators and washing machines and automobile fields are being electronically controlled by computers for the purpose of energy saving. Electronic devices such as LSI and CPU that perform electronic control have problems such as damage to electronic devices due to increased power consumption due to increased computer integration and faster operation, and increased heat generation. .

  Therefore, heat dissipation measures are necessary for computers, and conventionally heat sinks made of aluminum or die-casting have been used to dissipate heat in electronic component packages that are heat sources, but the heat dissipation characteristics with respect to the amount of heat generated are limited. It is reaching an area beyond. Furthermore, when the parts are made smaller, lighter, or complicated in shape in the future, there is a problem that metal such as die-casting has poor productivity and the shape is limited.

  In view of this, a proposal has been made to improve molding processability and balance the heat radiation characteristics by resinization by highly filling a conductive material with carbon fiber or metal as a filler in a resin material (for example, Patent Document 1).

  In addition, the heat radiating member is often in direct contact with heat-generating electronic components such as LSI, and both high heat radiating characteristics and insulating properties are required. Regarding this point, a method of highly filling aluminum nitride, which is an insulating material and has high thermal conductivity, as a filler has been proposed (for example, Patent Document 2).

In either case, the essential cause of the deterioration of the molding processability of the resin composite material, which is highly filled with an inorganic filler in order to increase thermal conductivity, has not been solved. Furthermore, the conventional technology goes against the demand for weight reduction of electronic devices in which the heat dissipating member becomes heavy in order to highly fill the inorganic filler having a high specific gravity. In particular, the tendency is remarkable in the insulating high thermal conductive resin composite material.
JP 2005-146214 A JP 2006-282678 A

  The present invention solves the above problems and realizes a high thermal conductivity resin composite material by suppressing the filler addition rate so as to maintain the processability and moldability that are the original features of the resin material and ensuring insulation. It provides a means.

In view of this situation, the present inventors have intensively studied to arrive at the present invention. That is, the present invention relates to a resin composite material including the following (A) and (B), having a thermal conductivity of 0.8 W / mK or more, a specific gravity of 2 or less, and a volume resistivity of 10 ¹⁰ Ωcm or more.
(A) resin,
(B) An insulating metal oxide on the surface of a conductive ultrafine powder made of a spherical carbon material having a particle diameter of 1 nm to 500 nm, a fibrous material having a cross-sectional diameter of 1 nm to 500 nm, or a plate-like carbon material having a thickness of 1 nm to 3000 nm. Alternatively, when a film made of the hydrate is applied, the thickness of the film is 0.3 nm or more, and the conductive ultrafine powder is spherical, the particle diameter or less, and in the case of a fibrous form An insulated ultrafine powder having a cross-sectional diameter equal to or smaller than a thickness in the case of a plate shape.

  According to the present invention, a resin composite material to which a small amount of an insulated ultrafine powder obtained by insulatingly coating a conductive ultrafine powder, particularly an insulated ultrafine powder insulated by an insulating metal oxide or a hydrate thereof, It exhibits high thermal conductivity while maintaining the excellent moldability, insulation, and lightness inherent in resin materials.

  Examples of the resin component of the present invention include PVC resins, phenoxy resins, fluorocarbon resins, PPS resins, PPE resins, polystyrene resins, polyolefin resins, polyimide resins, polyamide resins and other thermoplastic resins, or mixed resins thereof. be able to. Particularly desirable is a polyimide resin having excellent insulating properties and excellent adhesion to a metal layer such as copper.

  In addition, the resin component when blended with the insulating ultrafine powder is not only in the form of a polymer but also in the form of a polymerizable compound, that is, a phenoxy resin, an epoxy resin, a cyanate ester resin, a vinyl ester resin, a phenol resin, It may be blended as a polymerizable compound such as a monomer or oligomer of a thermosetting resin such as xylene resin, melamine resin or polyurethane resin, and polymerized later. Particularly desirable is a resin composition containing an epoxy resin. This is because when used for a wiring board or the like, the adhesion strength with a metal layer such as copper is large.

  The conductive ultrafine powder of the present invention, when added alone to a resin material, has an effect of reducing the volume resistance of the resin composite material, that is, imparting conductivity. As a material constituting such a conductive ultrafine powder, conductive carbon materials such as natural graphite, artificial graphite, furnace carbon black, graphitized carbon black, carbon nanotube, and carbon nanofiber are used. With respect to conductive carbon materials, with the exception of some precious metals, the metal that is a typical conductor is not only easily oxidized, but also has a potential for dust explosion, as well as its conductivity. . In addition, metal atoms diffuse from the ultrafine powder into the insulator medium, thereby lowering the insulating properties of the composite material. Conductive carbon materials do not have these problems, and the carbon material has a specific gravity of 2.2, which is unique to other conductive materials and conventional high thermal conductivity fillers, and reduces the weight of high thermal conductivity composite materials. There is also an effect.

  Examples of the conductive ultrafine powder used in the present invention include spherical carbon materials having a particle diameter of 1 nm to 500 nm, preferably 5 nm to 300 nm, more preferably 10 nm to 100 nm. Such a spherical carbon material, for example, carbon black is obtained by thermally decomposing a hydrocarbon raw material in a gas phase. Graphitized carbon black vaporizes a carbon material by arc discharge and cools and solidifies the vaporized carbon vapor in a decompression vessel maintained at an internal pressure of 2 to 19 Torr by an atmosphere system of He, CO, or a mixed gas thereof. Can be obtained.

  Specifically, Seest S manufactured by Tokai Carbon Co., Ltd., conductive carbon black # 5500, # 4500, # 4400, # 4300, graphitized carbon black # 3855, # 3845, # 3800, or Mitsubishi Chemical Corporation ) # 3050B, # 3030B, # 3230B, # 3350B, MA7, MA8, MA11, or Ketjen Black EC, Ketjen Black EC600JD manufactured by Lion Corporation. Here, the spherical shape does not necessarily need to be a strict spherical shape, and may be an isotropic shape. For example, it may be a polyhedron with corners.

  The conductive ultrafine powder used in the present invention includes a fibrous carbon material having a cross-sectional diameter of 1 nm to 500 nm, preferably 5 nm to 300 nm, more preferably 10 nm to 200 nm. The length is preferably 3 to 300 times the cross-sectional diameter. Such fibrous carbon materials such as carbon nanofibers and carbon nanotubes can be obtained by mixing cobalt and iron organometallic compounds as a catalyst and a hydrocarbon raw material in a gas phase and heating. Some carbon nanofibers are obtained by melt spinning a phenolic resin and heating in a non-active atmosphere. Specific examples include VGCF and VGNF manufactured by Showa Denko KK, Carbale manufactured by GSI Creos Co., Ltd., and carbon nanofiber manufactured by Gunei Chemical Industry Co., Ltd. Here, the fiber shape means a shape extending in one direction, and may be, for example, a square shape, a round bar shape, or an oblong shape.

  Furthermore, the conductive ultrafine powder used in the present invention includes a plate-like carbon material having a thickness of 1 nm to 500 nm, desirably 5 nm to 300 nm, more desirably 10 nm to 200 nm. The length and width are preferably not less than 3 times and not more than 300 times the thickness. Such a plate-like carbon material can be obtained, for example, by refining, pulverizing, and classifying natural graphite or artificial graphite. Examples thereof include SNE series and SNO series manufactured by ESC Corporation, graphite made in Japan, scale-like graphite powder, exfoliated graphite powder, and the like. These may be further pulverized and precision classified. In addition, plate shape means the shape which one direction shrunk here, for example, a flat spherical shape and a scale shape may be sufficient.

  When the particle diameter, the cross-sectional diameter or the thickness is smaller than the above range, the conductivity decreases due to the quantum size effect. In addition, it is difficult to manufacture and cannot be used industrially, and handling is also difficult due to aggregation. On the other hand, when the particle diameter, the cross-sectional diameter or the thickness is larger than the above range, the continuous layer is not formed in the range of 50 vol% or less, that is, in the addition ratio which does not deteriorate the resin characteristics. In addition, when the shape of the conductive ultrafine powder is fiber or plate, the aspect ratio is preferably 3 to 300. Among the conductive ultrafine powders used in the present invention, the fibrous shape is more preferable than the spherical shape or the plate shape. This is because the amount of addition required for forming a continuous layer as a resin composite material having a thermal conductivity of 20 or more is less, for example, 30 vol% or less in the fibrous form.

  It is desirable to subject the surface of the conductive ultrafine powder made of a carbon material to an oxidation treatment in advance in order to apply an insulating metal oxide film as described below, if necessary. As oxidation treatment, oxidation treatment in an oxygen-containing atmosphere, oxidation treatment with an aqueous solution of nitric acid, potassium permanganate, hydrogen peroxide, etc., oxidation treatment using an oxidation catalyst composed of ruthenium trichloride and sodium hypochlorite, etc. Is mentioned.

  The insulating film of the present invention is one of the purposes for ensuring the overall insulation of the resin composite material. Further, by coating the surface of the conductive ultrafine powder, the thermal conductivity of the insulated ultrafine powder itself is doubled from the thermal conductivity of the insulating film constituent material. For this reason, the thickness of the insulating coating is less than the particle diameter when the conductive ultrafine powder to be coated is spherical, less than its cross-sectional diameter when it is fibrous, and less than its thickness when it is plate-like. is there. More preferably, the thickness of the insulating film is 0.3 nm or more, and the ratio of the particle diameter, the cross-sectional diameter, or the thickness of the conductive ultrafine powder to be coated is 0.01 or more and 0.9 or less. Most desirably, the thickness of the insulating film is 0.3 nm or more, and the ratio of the particle diameter, the cross-sectional diameter, or the thickness of the conductive ultrafine powder to be coated is 0.01 or more and 0.5 or less. If it is thinner than the above range, the insulation effect may be reduced and conduction may not be prevented. On the other hand, if it is thicker than this, the thermal conductivity doubling effect of the conductive ultrafine powder as the core may be reduced, and the thermal conductivity of the resin composite material may be reduced.

  The material of the insulating film is an insulating metal oxide or a hydrate thereof. Examples include insulating oxides such as silicon dioxide, dialuminum trioxide, and zirconium dioxide. Alternatively, examples of these hydrates include silicon tetrahydroxide, aluminum trihydroxide, and zirconium tetrahydroxide. In the case of a hydrate, a structure in which a part thereof is dehydrated and condensed is also included.

  In the present invention, it is preferable to subject the insulated ultrafine powder to a surface treatment to make it hydrophobic. An organosilicon compound can be used for the surface treatment. Illustrative examples include one or more compounds selected from the group consisting of alkoxysilanes, organosilane compounds produced from alkoxysilanes, polysiloxanes, modified polysiloxanes, terminal-modified polysiloxanes, and fluoroalkylsilanes. Of these, alkoxysilane, fluoroalkylsilane, and polysiloxane are preferable.

  Specific examples of the alkoxysilane include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane. Methoxysilane, decyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltri Examples include methoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane.

  Considering the adhesion strength to the insulating metal oxide or metal hydroxide film particles formed on the conductive ultrafine powder, methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, isobutyltrimethoxysilane, phenyltrimethoxysilane An alkoxysilane such as ethoxysilane or an organosilane compound produced from the alkoxysilane is more preferable.

  Examples of the polysiloxane include a polysiloxane having a methylhydrogensiloxane unit, a polyether-modified polysiloxane, and a terminal carboxylic acid-modified polysiloxane having a terminal modified with a carboxylic acid.

  Specific examples of the fluoroalkylsilane include trifluoropropyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecylmethyldimethoxysilane, trifluoropropylethoxysilane, Examples include decafluorooctyltriethoxysilane and heptadecafluorodecyltriethoxysilane.

  A coupling agent can be used for the surface treatment. As an example, one or more coupling agents selected from the group consisting of silane, titanate, aluminate and zirconate coupling agents can be used.

  Among the coupling agents described above, the silane coupling agent includes a part of the organosilicon compounds mentioned above, that is, alkoxysilane, but the silane coupling agent other than alkoxysilane includes methyltrichlorosilane, Phenyltrichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, isobutyltrichlorosilane, decyltrichlorosilane, vinyltrichlorosilane, vinyltrichlorosilane, γ-aminopropyltrichlorosilane, γ-glycidoxy Propyltrichlorosilane, γ-mercaptopropyltrichlorosilane, γ-methacryloxypropyltrichlorosilane, N-β (aminoethyl) -γ-aminopropyltrichlorosilane, etc. It is.

  Examples of titanate coupling agents include isopropyl tristearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, tetraoctyl bis (ditridecyl phosphate) titanate, tetra (2- Examples include 2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphate titanate, bis (dioctylpyrophosphate) oxyacetate titanate, and bis (dioctylpyrophosphate) ethylene titanate.

  Examples of the aluminate coupling agent include acetoalkoxy aluminum diisopropylate, aluminum diisopropoxy monoethyl acetoacetate, aluminum trisethyl acetoacetate, aluminum trisacetylacetonate and the like.

  Examples of the zirconate coupling agent include zirconium tetrakisacetylacetonate, zirconium dibutoxybisacetylacetonate, zirconium tetrakisethylacetoacetate, zirconium tributoxymonoethylacetoacetate, zirconium tributoxyacetylacetonate and the like.

  The amount of the surface treatment agent used varies depending on the degree of dehydration, but is preferably 0.01 to 30 parts by weight with respect to 100 parts by weight of the insulated ultrafine powder. Within this range, 0. The insulated ultrafine powder can be sufficiently dispersed in the resin, and the adhesion between the insulated ultrafine powder and the resin can be ensured. More preferably, it is 0.1-25 weight part, Most preferably, it is 1-15 weight part.

  You may perform a baking process, after filtering and drying through surface treatment. Usually, the calcination treatment is carried out by holding in a temperature range of 200 ° C. to 1500 ° C. for 30 minutes to 24 hours. However, when the conductive ultrafine powder is a carbon material, the firing atmosphere needs to be non-oxidizing. That is, it is necessary to block oxygen by performing nitrogen substitution or argon substitution.

  The insulated ultrafine powder of the present invention provides a high thermal conductivity resin composite material having a thermal conductivity of 0.8 W / mK or more by blending the resin with an amount of 50 vol% or less, preferably 5 to 50 vol%. It is done. That is, the compounding ratio with the resin is in the range of 95/5 to 50/50 by volume ratio (resin / ultra fine powder). In order to realize a high thermal conductivity resin composite material having a thermal conductivity of 0.8 W / mK or more, when a conventional high thermal conductivity filler is used, it is necessary to blend the filler in an amount of about 50 vol% or more. When insulated ultrafine powder is used, the insulated ultrafine powder may be blended in an amount of 50 vol% or less. The resin composite material of the present invention exhibits high thermal conductivity without impairing molding processability and light weight, which are the original characteristics of the resin material.

  The high thermal conductivity resin composite material of the present invention can be used by further adding a filler as required for purposes other than high thermal conductivity. Fillers include glass fiber for improving elastic modulus, calcium carbonate for reducing molding shrinkage, talc used for improving surface smoothness and wear resistance, and mica used for improving dimensional stability. Is mentioned. Examples of the filler that imparts flame retardancy, that is, a flame retardant, include halogen-based or phosphorus-based flame retardants, aluminum hydroxide, and magnesium hydroxide.

  In the present invention, the amount of the insulated ultrafine powder added to the resin composition is 5 to 50 vol%, preferably 5 to 30 vol%. If it is less than this, a continuous layer is not formed in the resin composition, and sufficient thermal conductivity cannot be obtained. On the other hand, when the amount is larger than this, the original processability of the resin composition is impaired.

Since the high thermal conductivity resin composite material of the present invention uses a carbon material as a raw material for the insulated ultrafine powder, its specific gravity can be reduced to 2 or less. In addition, the volume resistivity of the high thermal conductivity resin composite material of the present invention is 10 ¹⁰ Ωcm or more.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

Example 1
Add 2kg of carbon black (spherical particle diameter 50-100nm, average particle size 70nm, Seest S manufactured by Tokai Carbon Co., Ltd.) and 2.1kg of tetrapropyloxytitanate (TPT manufactured by Mitsubishi Gas Chemical Co., Ltd.) to 40L of isopropanol. The mixture was stirred and mixed at room temperature for 1 hour. To this dispersion solution, 2 kg of distilled water was added dropwise over 2 hours, and the mixture was further stirred for 2 hours. While distilling water-containing isopropanol at a vacuum of 17 kPa, 45 L of N, N-dimethylacetamide was added dropwise to replace the solvent. Further, 0.31 kg of phenyltrimethoxylane was added, and the mixture was hydrophobized by heating at 100 ° C. for 4 hours, filtered, naturally dried for 12 hours, and calcined at 350 ° C. for 30 minutes in a nitrogen atmosphere. As a result, 2.8 kg of surface-treated insulated ultrafine powder was obtained.

The obtained insulated ultrafine powder (1.5 kg) and polyphenylene sulfide (3.5 kg) were melt-kneaded at 300 ° C. by a twin screw extruder and pelletized to obtain 5 kg of a resin composite material. This means that 20 vol% of the insulated ultrafine powder that has been made hydrophobic is added. The resin composite material pellets were hot pressed and the thermal conductivity was measured to be 2.5 (W / m · K). The specific gravity of the resin composite material was 1.4, and the volume resistivity was 2 × 10 ¹³ Ωcm.

Example 2
The same procedure as in Example 1 was performed except that isopropyltristearoyl titanate was used instead of phenyltrimethoxylane in Example 1. The resin composite material had a thermal conductivity of 2.1 (W / m · K) and a specific gravity of 1.4.

Example 3
The same procedure as in Example 1 was conducted except that zirconium dibutoxybisacetylacetonate was used instead of phenyltrimethoxylane in Example 1. The resin composite material had a thermal conductivity of 1.9 (W / m · K), a specific gravity of 1.4, and a volume resistivity of 3 × 10 ¹⁴ Ωcm. Met.

Comparative Example 1
The same procedure as in Example 1 was performed except that surface treatment with phenyltrimethoxysilane was not performed. The obtained resin composite material became conductive, and the volume resistivity could not be measured.

Example 4
To 30 L of isopropanol, 300 g of carbon nanofibers (fibrous shape having a cross-sectional diameter of 150 nm and a length of 5 to 6 μm) obtained by the vapor phase growth method and 640 g of tetrapropyloxytitanate were added and stirred and mixed at room temperature for 1 hour. To this dispersion solution, 660 g of distilled water was added dropwise over 1 hour. After completion of the dropwise addition, stirring was further continued for 2 hours. Then, 35 L of dimethylacetamide was added to replace the solvent while distilling hydrous propanol in the same manner as in Example 1. Further, 460 g of phenyltrimethoxylane was added and heating was continued to make the surface of the insulated ultrafine powder hydrophobic. Then, after filtering and air-drying for 12 hours, it vacuum-dried at 100 degreeC. When the surface of the powder obtained with a scanning electron microscope was confirmed, a film of titanium dioxide having a thickness of 30 to 70 nm and an average thickness of 50 nm was formed.

  480 g of the obtained insulated ultrafine powder and 1.9 kg of polyphenylene sulfide were melt-kneaded at 300 ° C. using a single screw extruder. This means that 10 vol% of insulating ultrafine powder (filler) was added. Using the obtained resin composite material, the thermal conductivity was measured in the same manner as in Example 1. As a result, it was 1.8 (W / m · K). The specific gravity of the resin composite material was 1.4.

Example 5
In synthesizing the insulated ultrafine powder, the same procedure as in Example 4 was performed except that 300 g of carbon nanofibers were heated at 100 ° C. in a 60 wt% nitric acid aqueous solution and subjected to an oxidation treatment. When the thermal conductivity was measured in the same manner as in Example 1, it was 1.6 (W / m · K). The specific gravity of the resin composite material was 1.4, and the volume resistivity was 4 × 10 ¹³ Ωcm.

Example 6
Instead of the carbon black of Example 1, natural graphite (plate shape having a thickness of 100 to 200 nm, an average thickness of 150 nm, 1 to 3 μm square, and an average of 2 μm square) was used in the same manner as in Example 1. When the surface of the powder obtained with a scanning electron microscope was confirmed, a film of titanium dioxide having a thickness of 30 to 70 nm and an average thickness of 50 nm was formed. In the same manner as in Example 1, a resin composite material pellet was obtained by melt-kneading with polyphenylene sulfide, and the thermal conductivity of the plate formed by hot pressing was measured to be 2.1 (W / m · K). It was. The specific gravity was 1.4, and the volume resistivity was 6 × 10 ¹² Ωcm. Met.

Example 7
Using a spherical carbon black having a particle diameter of 10 to 30 nm and an average diameter of 25 nm in place of the carbon black used in Example 1, a film was formed by the sol-gel method in the same manner as in Example 1, followed by liquid phase dehydration. Surface treatment was performed using trimethoxysilane to make it hydrophobic. When a plate of a resin composite material with polyphenylene sulfide was molded and the thermal conductivity was measured in the same manner as in Example 1, it was 3.2 (W / m · K). The specific gravity was 1.4, and the volume resistivity was 8 × 10 ¹² Ωcm.

Example 8
In synthesizing the insulated ultrafine powder, the same procedure as in Example 1 was performed except that tetrabutyloxyzirconate was used instead of tetrapropyloxytitanate. When the surface of the powder obtained by a scanning electron microscope was confirmed, a film of zirconium dioxide hydrate having a thickness of 30 to 70 nm and an average thickness of 50 nm was formed. When the thermal conductivity of the polyphenylene sulfide composite material was measured in the same manner as in Example 1, it was 2.4 (W / m · K). The specific gravity of the cured product was 1.4, and the volume resistivity was 2 × 10 ¹³ Ωcm. Met.

Example 9
A hydrophobized insulated ultrafine powder was synthesized in the same manner as in Example 6 except that tetraethoxysilicate was used instead of tetrapropoxytitanate. When the surface of the powder obtained by a scanning electron microscope was confirmed, a film of silicon dioxide hydrate having a thickness of 30 to 50 nm and an average thickness of 40 nm was formed. The result of melt kneading with polyphenylene sulfide in the same manner as in Example 6 and measuring the thermal conductivity of the resin composite material was 2.8 (W / m · K). The specific gravity was 1.4, and the volume resistivity was 9 × 10 ¹² Ωcm. Met.

Example 10
The procedure was the same as Example 4 except that the amount of tetrapropoxy titanate added was 128 g. When the surface of the powder obtained with a scanning electron microscope was confirmed, a film of titanium dioxide hydrate having a thickness of 2 to 4 nm and an average thickness of 3 nm was formed. When the thermal conductivity of the resin composite material with polyphenylene sulfide was measured in the same manner as in Example 4, it was 6.1 (W / m · K) and the volume resistivity was 5 × 10 ¹¹ Ωcm. Met.

Example 11
1 g of the insulated ultrafine powder obtained in Example 1, 9 g of bisphenol A type epoxy monomer, 0.16 g of imidazole-based curing catalyst, and 10 g of methyl ethyl ketone as a solvent were pulverized and mixed with a homogenizer for 1 minute, and placed in a Teflon petri dish. After putting and drying, a cured sheet was obtained by curing at 120 ° C. for 1 hour. This means that 5 vol% of the insulated ultrafine powder was added. The thermal conductivity was 2.8 (W / m · K). The specific gravity of the cured product is 1.3.

Example 12
Except for using carbon nanofibers (cross-sectional diameter: 300-500 nm, average cross-sectional diameter: 400 nm, length: 50 μm, fibrous) synthesized by melt spinning, and using tetrabutyloxyzirconate instead of tetrapropoxytitanate In the same manner as in Example 4. When the surface of the powder obtained by a scanning electron microscope was confirmed, a film of zirconium dioxide hydrate having a thickness of 90 to 130 nm and an average of 110 nm was formed. A cured epoxy composite plate was prepared in the same manner as in Example 11, and the thermal conductivity was measured in the same manner as in Example 1. The result was 2.2 (W / m · K). The specific gravity was 1.5, and the volume resistivity was 4 × 10 ¹⁴ Ωcm.

Example 13
All were the same except that the amount of tetrapropyloxyzirconate added in Example 6 was 64 g. When the surface of the obtained insulated ultrafine powder was confirmed with a scanning electron microscope, a film of zirconium dioxide hydrate having a thickness of 2 to 7 nm and an average thickness of 5 nm was formed. A cured product obtained by mixing this hydrophobized insulated ultrafine powder with an epoxy resin in the same manner as in Example 11 had a thermal conductivity of 9.4 (W / m · K), a specific gravity of 1.3, and a volume. The resistivity was 3 × 10 ¹¹ Ωcm.

Example 14
The procedure of Example 2 was repeated except that the amount of tetrapropyloxytitanate added in Example 2 was 1.2 kg. When the surface of the obtained insulated ultrafine powder was confirmed with a scanning electron microscope, a film of titanium dioxide hydrate having a thickness of 70 to 130 nm and an average thickness of 100 nm was formed. The obtained resin composite material had a thermal conductivity of 2.3 (W / m · K), a specific gravity of 1.3, and a volume resistivity of 4 × 10 ¹⁴ Ωcm.

Comparative Example 2
The procedure was the same as Example 10 except that 7 g of the insulated ultrafine powder in Example 11 and 3 g of bisphenol A type epoxy monomer were mixed. This means that 60 vol% was added. In this case, only a very brittle cured product was obtained. The thermal conductivity could not be measured.

Comparative Example 3
The procedure of Example 11 was repeated except that the amount of tetrapropyloxytitanate added was 66 g in Example 1. When the surface of the obtained insulated ultrafine powder was confirmed with a scanning electron microscope, a titanium dioxide film having a thickness of 200 to 400 nm and an average thickness of 300 nm was formed. The obtained cured product had a thermal conductivity of 0.6 and a specific gravity of 1.3.

Comparative Example 4
The same procedure as in Example 11 was performed except that tetrapropyloxytitanate was not added in Example 1. The volume resistivity of the obtained cured product was 10 ¹⁰ Ωcm or less that could not be measured with an insulating high resistance meter.

Claims (8)

A resin composite material comprising (A) and (B), having a thermal conductivity of 0.8 W / mK or more, a specific gravity of 2 or less, and a volume resistivity of 10 ¹⁰ Ωcm or more.
(A) resin,
(B) Insulating metal oxide on the surface of a conductive ultrafine powder made of a spherical carbon material having a particle diameter of 1 nm to 500 nm, a fibrous material having a cross-sectional diameter of 1 nm to 500 nm, or a plate-like carbon material having a thickness of 1 nm to 500 nm. Alternatively, when a film made of the hydrate is formed, the thickness of the film is 0.3 nm or more, and the conductive ultrafine powder is spherical, the particle diameter or less, and in the case of a fibrous form Insulated ultrafine powder characterized by having a cross-sectional diameter or less, or a plate-like thickness or less. 2. The resin composite material according to claim 1, wherein a mixing ratio of the resin and the insulated ultrafine powder is in a range of 95/5 to 50/50 by volume ratio (resin / insulated ultrafine powder). The resin composite material according to claim 1 or 2, wherein the insulating metal oxide is titanium dioxide, zirconium dioxide, tantalum pentoxide, silicon dioxide, dialuminum trioxide, or a solid solution thereof. The carbon material is at least one selected from the group consisting of carbon nanofibers, natural graphite, furnace carbon black, graphitized carbon black, carbon nanotubes, and artificial graphite. Resin composite material. The resin composite material according to any one of claims 1 to 4, wherein the carbon material is obtained by subjecting a surface to an oxidation treatment in advance. The resin composite material according to any one of claims 1 to 5, wherein the insulating ultrafine powder is further subjected to a surface treatment. The surface treatment is performed using one or more organosilicon compounds selected from the group consisting of alkoxysilanes, organosilane compounds generated from alkoxysilanes, polysiloxanes, modified polysiloxanes, terminal-modified polysiloxanes, and fluoroalkylsilanes. The resin composite material according to claim 6, which is a material. The resin composite material according to claim 6, wherein the surface treatment is performed using one or more coupling agents selected from the group consisting of silane-based, titanate-based, aluminate-based, and zirconate-based coupling agents.