JP2020029384A - Highly thermal conductive inorganic filler composite particles and method for producing the same - Google Patents

Abstract

To provide highly thermal conductive inorganic filler composite particles excellent in thermal conductivity and insulation, and to provide a method for producing the same.SOLUTION: Highly thermal conductive inorganic filler composite particles have insulation properties obtained by a surface of graphite being covered with or bonded by an alumina hydrate gel and a surface of the alumina hydrate gel being covered with or bonded by a basic magnesium carbonate. The highly thermal conductive inorganic filler composite particles have insulation properties obtained by a surface of graphite being covered with or bonded by alumina and a surface of the alumina being covered with or bonded by a basic magnesium carbonate from which hydrated water is removed. A method for producing the highly thermal conductive inorganic filler composite particles comprises allowing a surface of graphite to be covered with or bonded by an alumina hydrate gel with the use of an aluminate or an aluminum alkoxide, and allowing a surface of the alumina hydrate gel to be covered with or bonded by a basic magnesium carbonate from a water-soluble magnesium salt and a water-soluble metal carbonate.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method of coating a surface of graphite with alumina hydrate gel or alumina or binding alumina, and coating or binding the surface of the alumina hydrate gel or alumina with basic magnesium carbonate. The present invention relates to a conductive inorganic filler composite particle and a method for producing the same.

In recent years, with the miniaturization and weight reduction of electric and electronic devices such as semiconductor devices and ICs, high-density mounting of electronic components has been progressing, and heat generation from the electronic components tends to increase. When the generated heat is accumulated in the electronic component, the durability is adversely affected. Therefore, the need for a highly thermally conductive filler capable of efficiently releasing the generated heat from the electronic component is increasing.
Conventionally, alumina, magnesia, silicon carbide, aluminum nitride, boron nitride, metal powder, graphite, and the like are generally known as high thermal conductive fillers. Various high thermal conductive fillers have advantages and disadvantages as shown in FIG. Alumina, magnesia, and silicon carbide all have high hardness, and thus have a problem that it is difficult to combine them with electronic components. Aluminum nitride and boron nitride have a problem of being expensive, and in addition, aluminum nitride has a problem of being chemically unstable. Metal powder has a problem that it is difficult to apply to a heat radiation material of an electronic component and a problem that it is chemically unstable, because it is conductive and has low insulation. Although graphite is particularly inexpensive and has excellent thermal conductivity, it has a problem that it is difficult to apply graphite alone to a heat dissipation material for electronic components that require insulation because of its low conductivity and conductivity.
On the other hand, there has been proposed an inorganic filler composite in which boehmite or zinc oxide is bonded or attached to the surface of graphite (graphite) as a thermally conductive filler to impart insulation to graphite (Patent Document 1). In addition, the applicant of the present application has proposed high heat conductive inorganic filler composite particles having insulating properties in which basic magnesium carbonate is coated or bonded to the surface of graphite (Patent Document 2).

WO2013 / 039103 Japanese Patent No. 6222840

  However, the inorganic filler composite described in Patent Literature 1 may not be sufficiently kneaded into the filling material depending on the shape of boehmite or zinc oxide that is combined with graphite, and may not easily function as a high thermal conductive inorganic filler. There is. Further, in order to combine boehmite or zinc oxide with graphite, it is necessary to synthesize in the presence of hot water of high temperature and high pressure, which causes a problem that the production cost is increased. The highly thermally conductive inorganic filler composite particles described in Patent Document 2 have excellent thermal conductivity and have insulating properties. However, the higher the thermally conductive filler used for electronic components, the better the insulating properties, and the better the insulating properties. Is desired.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide highly thermally conductive inorganic filler composite particles having excellent thermal conductivity and insulating properties, and a method for producing the same.

  In order to solve the above problems, the present inventors have conducted various studies and arrived at the present invention. That is, the first high thermal conductive inorganic filler composite particles have an insulating property in which the surface of graphite is coated or bonded with alumina hydrate gel, and the surface of the alumina hydrate gel is coated or bonded with basic magnesium carbonate. It is characterized by having. In addition, the second high thermal conductive inorganic filler composite particles are coated or bonded with alumina on the surface of graphite, and coated or bonded with basic magnesium carbonate from which water of hydration has been removed on the surface of the alumina to thereby provide insulation. It is characterized by having.

The third high thermal conductive inorganic filler composite particles were measured using a thermal conductivity meter of a resin sample prepared by blending the measurement target with the epoxy resin in the first or second high thermal conductive inorganic filler composite particles. The thermal conductivity is 0.80 W / m · K to 2.00 W / m · K, and the resistance of the molded object is measured by using a tester of the molded object produced by pressing the object to be measured. volume resistivity derived by dividing multiplying the area length ([rho _V) is characterized in that it is a 1000Ω · cm~100000Ω · cm. The fourth high thermal conductive inorganic filler composite particles have a thermal conductivity derived from the following formula (1) of 50 W / m · K to 150 W / m · in the first or second high thermal conductive inorganic filler composite particles. K.
λf = (λc−λm · Vm) / Vf * C (1)
(However, λf: thermal conductivity of high thermal conductive inorganic filler composite particles, λc: thermal conductivity of resin sample obtained by mixing 25 parts of high thermal conductive inorganic filler composite particles with 100 parts of resin, λm: thermal conductivity of resin Ratio, Vf: volume fraction of the high thermal conductive inorganic filler composite particles, Vm: volume fraction of the resin, C: correction coefficient (10))
The fifth highly thermally conductive inorganic filler composite particles are characterized by satisfying the following expression (2) in the first or second highly thermally conductive inorganic filler composite particles.
GV / T value = graphite content / 100 x volume resistivity (log ρv) / thermal conductivity
2.00 ≦ GV / T value ≦ 4.00 (2)
(However, the thermal conductivity is the thermal conductivity of a resin sample containing high thermal conductive inorganic filler composite particles.)
The sixth high heat conductive inorganic filler composite particles may have a graphite content of 45% by weight to 90% by weight in the first or second high heat conductive inorganic filler composite particles, and may be made of alumina hydrate gel or alumina. The content is 0.3% by weight to 10% by weight, and the content of basic magnesium carbonate is 5% by weight to 54.7% by weight.

The production method of the high thermal conductive inorganic filler composite particles is as follows: a suspension is prepared by adding graphite to an aqueous solution of aluminate, and carbon dioxide gas is blown into the suspension to coat or bond the alumina hydrate gel on the surface. Water-soluble metal carbonate to a suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to the graphite having the surface coated or bonded with the alumina hydrate gel. A step of obtaining a suspension by adding an aqueous solution of salt while stirring, a step of heating and stirring the suspension for aging, and a step of solid-liquid separation, washing with water and drying of the product obtained after aging. , Is characterized by including.
Further, the method for producing the high thermal conductive inorganic filler composite particles is the same as the method for producing the high thermal conductive inorganic filler composite particles described above, except that the suspension is prepared by adding graphite to an aqueous solution of aluminate. A process in which carbon dioxide gas is blown into the surface to obtain graphite having an alumina hydrate gel coated or bonded to the surface ”, and water is added to a suspension obtained by adding graphite to an alcohol solvent containing aluminum alkoxide, and alumina water is added. Obtaining a graphite coated or bonded to the surface of the hydrate gel ”.

The production method of the high thermal conductive inorganic filler composite particles is as follows: a suspension is prepared by adding graphite to an aqueous solution of aluminate, and carbon dioxide gas is blown into the suspension to coat or bond the alumina hydrate gel on the surface. Water-soluble metal carbonate to a suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to the graphite having the surface coated or bonded with the alumina hydrate gel. A step of obtaining a suspension by adding an aqueous solution of salt while stirring, a step of heating and stirring the suspension for aging, and a step of solid-liquid separation, washing with water and drying of the product obtained after aging. Removing the water of hydration of the basic magnesium carbonate coated or bound on the surface of the alumina hydrate gel by heat-treating the product obtained in the above step. And wherein the Rukoto.
Further, the method for producing the high thermal conductive inorganic filler composite particles is the same as the method for producing the high thermal conductive inorganic filler composite particles described above, except that the suspension is prepared by adding graphite to an aqueous solution of aluminate. A process in which carbon dioxide gas is blown into the surface to obtain graphite having an alumina hydrate gel coated or bonded to the surface ”, and water is added to a suspension obtained by adding graphite to an alcohol solvent containing aluminum alkoxide, and alumina water is added. Obtaining a graphite coated or bonded to the surface of the hydrate gel ”.

  In addition, the resin composition is characterized by being filled with the above-described high thermal conductive inorganic filler composite particles.

Conventional materials having both insulating properties and thermal conductivity are expensive, and many hard materials are difficult to process, so that it has been difficult to apply them to heat dissipation materials that require measures against heat and cost reduction.
On the other hand, the high thermal conductive inorganic filler composite particles of the present invention are a heat dissipating member for which heat measures and cost reduction are required because graphite, alumina hydrate gel and basic magnesium carbonate all form a cheap and soft composite. And very useful. In addition, since the highly heat-conductive inorganic filler composite particles of the present invention are composed of only a material having a small specific gravity, they are suitable for applications requiring weight reduction and are extremely useful. Specifically, in addition to the heat dissipation sheet, heat dissipation double-sided tape, heat dissipation grease, heat dissipation adhesive, heat dissipation resin substrate, heat dissipation flexible copper clad laminate, power device sealing material, white LED sealing material, LED die bonding material It can be used as an inorganic filler for heat dissipating members and heat dissipating materials such as heat dissipating underfill materials and casting materials, heat sinks, heat pipes, heat dissipating paints, heat dissipating engineering plastics, and heat dissipating elastomers, as well as LED lighting, LED TVs, and notebook PCs. It can be applied to applications requiring heat countermeasures, such as automobiles, solar power generation devices, mobile phones and smartphones. In addition, the high thermal conductive inorganic filler composite particles of the present invention are extremely useful in applications that require the above-described thermal measures, because they have greatly exceeded the thermal conductivity of alumina as a general-purpose high thermal conductive filler. . Further, according to the method for producing high thermal conductive inorganic filler composite particles of the present invention, the above-mentioned useful high thermal conductive inorganic filler composite particles can be produced simply and efficiently.

It is the table | surface which evaluated the characteristic of the high thermal conductive filler. The evaluation symbol indicates the result of relatively evaluating the characteristics of the high thermal conductive filler in the table. 3 is an SEM image showing a state in which the surface of graphite according to Example 1 is covered or bonded with an alumina hydrate gel. 3 is an SEM image of the high thermal conductive inorganic filler composite particles obtained in Example 1. 4 is an SEM image obtained by increasing the SEM image of FIG. 3 at a high magnification. It is a figure which shows the high heat conductive inorganic filler composite particle typically. 9 is an SEM image of the high thermal conductive inorganic filler composite particles obtained in Example 7. 14 is an SEM image of the high thermal conductive inorganic filler composite particles obtained in Example 13. 6 is an SEM image of a sample obtained in Comparative Example 1. 9 is an SEM image of a sample obtained in Comparative Example 3. 11 is a graph of thermogravimetric / differential heat (TG-DTA) of the highly thermally conductive inorganic filler composite particles obtained in Example 9. It is a figure which shows typically the measuring method of the volume resistivity ((rho) _V ) which concerns on the molded product of the high thermal conductive inorganic filler composite particle of an Example, and the sample of a comparative example.

  The high thermal conductive inorganic filler composite particles of the present invention are obtained by coating or bonding alumina hydrate gel on the surface of graphite, and coating or bonding basic magnesium carbonate on the surface of the alumina hydrate gel. Hereinafter, the high thermal conductive inorganic filler composite particles of the present invention may be simply referred to as “composite particles”.

The above composite particles can be produced by a production method including the following steps.
(A) adding graphite to an aqueous solution of aluminate to prepare a suspension, blowing carbon dioxide gas into the suspension to obtain graphite having a surface coated or bonded with alumina hydrate gel; An aqueous solution of a water-soluble metal carbonate is added with stirring to a suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to graphite having a hydrate gel coated or bound on the surface. It can be produced by including a step of obtaining a suspension, a step of aging the suspension by heating and stirring, and a step of solid-liquid separation, washing with water and drying of the product obtained after the aging.
The above-mentioned graphite coated or bound with the alumina hydrate gel is in a state where the graphite is contained in a suspension, or a suspension containing the graphite is solid-liquid separated, washed with water, dried and isolated. Either may be used. This is the same in all the following manufacturing methods. The solid-liquid separation may be performed by any means as long as the solid and liquid components can be separated, and examples include filtration, pressurization, and centrifugation. This is the same in all the following manufacturing methods.
(B) a step of adding water to a suspension obtained by adding graphite to an alcohol solvent containing aluminum alkoxide to obtain graphite having alumina hydrate gel coated or bonded on the surface; An aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt is added to graphite coated or bonded to the surface, and an aqueous solution of a water-soluble metal carbonate is added to the resulting suspension with stirring to obtain a suspension. It can be produced by including a step, a step of aging the suspension by heating and stirring, and a step of solid-liquid separation, washing and drying of the product obtained after the aging.

  In addition, the high thermal conductive inorganic filler composite particles of the present invention are obtained by coating or bonding alumina on the surface of graphite, and coating or bonding basic magnesium carbonate from which hydration water has been removed on the surface of the alumina.

The above composite particles can be produced by a production method including the following steps.
(C) adding graphite to an aqueous solution of aluminate to prepare a suspension, and blowing carbon dioxide gas into the suspension to obtain graphite having a surface coated or bonded with an alumina hydrate gel; An aqueous solution of a water-soluble metal carbonate is added with stirring to a suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to graphite having a hydrate gel coated or bound on the surface. A step of obtaining a suspension, a step of heating and stirring the suspension for aging, a step of solid-liquid separation, washing with water, and a drying of the product obtained after the aging, and a step of obtaining the product obtained in the step. To remove the water of hydration of the basic magnesium carbonate coated or bonded to the surface of the alumina hydrate gel by heat treatment.
(D) a step of adding water to a suspension obtained by adding graphite to an alcohol solvent containing an aluminum alkoxide to obtain graphite having alumina hydrate gel coated or bonded on the surface; An aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt is added to graphite coated or bonded to the surface, and an aqueous solution of a water-soluble metal carbonate is added to the resulting suspension with stirring to obtain a suspension. A step of heating and stirring the suspension to ripen it, a step of solid-liquid separation of the product obtained after aging, washing with water, and drying; and a step of heat-treating the product obtained in the step. Removing the water of hydration of the basic magnesium carbonate coated or bound on the surface of the alumina hydrate gel.

Basic magnesium carbonate to coat or bind the alumina hydrate gel or alumina, while the formula of the normal magnesium carbonate is represented by MgCO _3, represented by _{mMgCO 3 · Mg (OH) 2} · nH 2 O It is a hydrate, and its composition ratio varies depending on the production method. Usually, m is 3 to 5, and n is 3 to 8. The thermal decomposition behavior when basic magnesium carbonate is heated can be determined by the published technical literature, for example, (Hokkaido University Research Report, 69: 213-220, Journal of the Ceramic Society of Japan, 84 [6], 259-264, 1976) According to this, three stages of decomposition weight loss occur. Weight loss around 150 to 240 ° C is due to dehydration of crystallization water, weight loss around 350 to 420 ° C is due to dehydration of hydrate (hydroxyl group) and partial decarboxylation of carbonate, around 450 to 550 ° C Is reported to be the weight loss associated with decarboxylation of the remaining carbonates. The thermal decomposition behavior when heating the high thermal conductive inorganic filler composite particles of the present invention, as shown in FIG. 10, is presumed to cause a decrease in the amount of basic magnesium carbonate as in the above-mentioned report. By subjecting the high thermal conductive inorganic filler composite particles to heat treatment, water of hydration is removed, and composite particles in which anhydrous basic magnesium carbonate is coated or bonded to the surface of alumina can be obtained. The temperature of the heat treatment is preferably from 250C to 400C. If the temperature is lower than 250 ° C., water of hydration may not be removed. If the temperature is higher than 400 ° C., there is a possibility that weight loss due to partial decarboxylation of carbonate may occur. 250-400 hydrated water by heating at a temperature of ℃ is removed dehydration, possibly mMgCO ₃ · Mg (OH) ₂ or _{mMgCO 3 · xMg (OH) 2} · (1-x) a compound represented by MgO That is, it is considered that composite particles in which anhydrous basic magnesium carbonate was coated or bonded on the surface of alumina were obtained. The heating time is preferably 0.5 to 24 hours as long as the water of hydration of the basic magnesium carbonate is removed. If the time is shorter than 0.5 hour, the water of hydration of the basic magnesium carbonate cannot be sufficiently removed. Heating for more than 24 hours is wasteful and uneconomical. The alumina hydrate gel is dehydrated into alumina by the above heat treatment. The highly thermally conductive inorganic filler composite particles of the present invention in which anhydrous basic magnesium carbonate is coated or bonded to the surface of alumina not only has high insulation and high thermal conductivity, but also has a resin molding temperature of around 250 ° C. Since no weight loss (dehydration reaction) occurs, no foaming phenomenon occurs during molding, and it is particularly useful in molding a thermoplastic resin.

Examples of the aluminate as a raw material for producing an alumina hydrate gel that is coated or bonded to the surface of graphite in the above-mentioned production method include, but are not limited to, sodium aluminate and potassium aluminate. The alumina hydrate gel is a gel of a compound that can be represented by Al ₂ O ₃ .nH ₂ O (n: 1 to 4).

  Aluminum alkoxide, which is a raw material for producing an alumina hydrate gel coated or bonded to the surface of graphite in the above production method, includes aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, aluminum tert-butoxide, and the like. But not limited thereto.

  As a magnesium source which is a raw material for producing basic magnesium carbonate in the above-mentioned production method, water-soluble inorganic magnesium salts such as magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium phosphate and magnesium borate; and water-soluble inorganic salts such as magnesium acetate and magnesium formate. Examples of the organic magnesium salt include water-soluble inorganic magnesium salts, and among them, magnesium chloride or magnesium sulfate is more preferable. The compound serving as a magnesium source may be either an anhydride or a hydrate.

  Examples of the carbonic acid source as a raw material for producing basic magnesium carbonate in the above-mentioned production method include water-soluble metal carbonates, and among them, sodium carbonate and potassium carbonate are preferable. The compound serving as a carbonic acid source may be either an anhydride or a hydrate.

  Known graphite can be used as the graphite (hereinafter, also referred to as "graphite") in the above-described production method, and any of natural products and artificial products can be used. In addition, the shape is not limited, and any shape such as a granular shape, a square shape, a flat plate shape, and a scaly shape can be used.However, graphite exhibits excellent thermal conductivity in the planar direction as compared to the vertical direction. In particular, scaly graphite is particularly preferred. The particle diameter of graphite is preferably 0.1 to 500 μm in the case of granules or squares, and the average diameter in the plane direction is preferably 1 to 4000 μm in the case of plates or scales, and the aspect ratio which means the thickness in the plane direction. Is preferably from 2 to 2,000 in view of the thermal conductivity characteristics of graphite.

  The aging temperature at the time of heating in the aging step in the above-mentioned production method is preferably from 50 ° C to 100 ° C, more preferably from 60 ° C to 90 ° C. If the aging temperature is lower than 50 ° C., the formation rate of the basic magnesium carbonate is low, so that it takes a long time to combine with the alumina hydrate gel, which is not preferable. If the aging temperature exceeds 100 ° C., water evaporates, so that it is necessary to use equipment and equipment corresponding to the pressure so that water does not evaporate, which increases production costs in terms of equipment. The rate of raising the temperature to the aging temperature is not particularly limited as long as it is not too fast. The aging time is longer than 0 hours, and preferably 1 hour to 24 hours. Aging beyond 24 hours is wasteful and uneconomical. It is preferable to sufficiently stir the suspension in the aging step. If the stirring is not sufficient, the basic magnesium carbonate and the alumina hydrate gel may not be combined or the combination may not be sufficient, and the insulating properties may not be imparted to the composite particles.

The high thermal conductive inorganic filler composite particles of the present invention preferably have a graphite content of 45% by weight to 90% by weight. If the graphite content is less than 45% by weight, the thermal conductivity is reduced, and if it is more than 90% by weight, sufficient insulation cannot be provided.
The high thermal conductive inorganic filler composite particles of the present invention preferably have an alumina hydrate gel or alumina content of 0.3% by weight to 10% by weight. When the content of the alumina hydrate gel or alumina is less than 0.3% by weight, the coating amount of the alumina hydrate gel or alumina decreases, and the coating of the basic magnesium carbonate cannot be uniformly performed. If the content is more than 10% by weight, the hygroscopicity is increased, so that the heat resistance and the insulation are reduced. Further, the high thermal conductive inorganic filler composite particles of the present invention preferably have a basic magnesium carbonate content of 5% by weight to 54.7% by weight. If the content of the basic magnesium carbonate is less than 5% by weight, sufficient insulating properties will not be exhibited, and if it exceeds 54.7% by weight, high thermal conductivity, which is excellent in insulating properties but excellent in thermal conductivity. This is because the conductive inorganic filler composite particles cannot be obtained.

High thermal conductive inorganic filler composite particles of the present invention, the surface of graphite is coated or bonded with alumina hydrate gel or alumina, and the surface of the alumina hydrate gel or alumina is coated or bonded with basic magnesium carbonate. It has excellent thermal conductivity and insulation properties. It is preferable that the thermal conductivity of a resin sample prepared by blending an object to be measured with an epoxy resin using a thermal conductivity meter is 0.80 W / m · K to 2.00 W / m · K. If it is less than 0.80 W / m · K, high thermal conductivity cannot be expected. The reason that the thermal conductivity does not exceed 2.00 W / m · K is that graphite is made of alumina hydrate gel or alumina. And the basic magnesium carbonate coats or binds, which limits the thermal conductivity of graphite.
In addition, the thermal conductivity of the highly thermally conductive inorganic filler composite particles themselves can be derived using the following equation (1). The method of deriving the thermal conductivity of the highly heat-conductive inorganic filler composite particles themselves using Equation (1) is the same as the method described in Patent Document 2.
λf = (λc−λm · Vm) / Vf * C (1)
(However, λf: thermal conductivity of the high thermal conductive inorganic filler composite particles, λc: thermal conductivity of a resin sample in which 25 parts of the high thermal conductive inorganic filler composite particles are blended with 100 parts of the resin, λm: thermal conductivity of the resin Ratio, Vf: volume fraction of the high thermal conductive inorganic filler composite particles, Vm: volume fraction of the resin, C: correction coefficient (10))
The thermal conductivity of the high thermal conductive inorganic filler composite particles derived by this method is preferably from 50 W / m · K to 150 W / m · K. If the thermal conductivity is less than 50 W / m · K, a high thermal conductivity cannot be expected. The reason that the thermal conductivity does not exceed 150 W / m · K is that graphite is made of alumina hydrate gel or alumina and basic magnesium carbonate. Is coated or bonded, which limits the thermal conductivity of graphite.

Volume resistance derived by multiplying the resistance value (R) measured using a tester of a molded product made by pressing the measurement object of the high thermal conductive inorganic filler composite particles by the cross-sectional area of the molded product and dividing by the length The rate (ρ _V ) is preferably from 1000 Ω · cm to 100000 Ω · cm. When the volume resistivity ([rho _V) is below 1000 [Omega] · cm, is not preferable for use in electronic parts where high insulating properties are required, also if the volume resistivity ([rho _V) is exceeds the 100000Ω · cm This is because there is a concern about a decrease in thermal conductivity.

The thermal conductivity and the volume resistivity (ρ _V ) of the high thermal conductive inorganic filler composite particles are in a trade-off relationship with the graphite content. Therefore, it is possible to evaluate the high thermal conductive inorganic filler composite particles by setting a parameter represented by the following equation (2).
GV / T value = graphite content / 100 × volume resistivity (log .rho _V) / thermal conductivity
2.00 ≦ GV / T value ≦ 4.00 (2)
(However, the thermal conductivity is the thermal conductivity of the resin sample in which the high thermal conductive inorganic filler composite particles are blended.) If the GV / T value of the parameter set in this way is less than 2.00, the thermal conductivity is excellent and the insulating property is high. This is because it is not possible to obtain highly thermally conductive inorganic filler composite particles having excellent thermal conductivity, and if the GV / T value is more than 4.00, the highly thermally conductive inorganic filler composite particles having excellent insulation and excellent thermal conductivity. Is not obtained.

  The specific gravity of graphite, alumina hydrate gel and basic magnesium carbonate of the constituent materials related to the high thermal conductive inorganic filler composite particles of the present invention does not exceed 3, and the specific gravity exceeds 3 and is close to 4 for general-purpose high heat. It is lighter than alumina, which is a conductive filler, and can contribute to the weight reduction of the heat radiation material of the filling material. The layer of the alumina hydrate gel coated or bonded to the graphite of the highly thermally conductive inorganic filler composite particles of the present invention has a mesh structure as shown in FIGS. 2 and 5. For this reason, the thickness of the coating layer is increased, and the distance between the coating layer and the conductive graphite particles can be maintained. It is presumed that this also contributes to the improvement of the insulating property of the high thermal conductive inorganic filler composite particles of the present invention.

  The high thermal conductive inorganic filler composite particles of the present invention are not limited to the material to be filled as long as they can be filled, but are preferably filled into a resin composition, especially a substrate or semiconductor package that requires insulation and heat dissipation. be able to. Although the resin used for the resin composition is not particularly limited, epoxy resin, silicone resin, melamine resin, urea resin, phenol resin, unsaturated polyester, fluorine resin, polyimide, polyamide imide, polyether imide, polyamide such as nylon, poly Butylene terephthalate, polyester such as polyethylene terephthalate, polybenzimidazole, aramid resin, polyphenylene sulfide, wholly aromatic polyester, liquid crystal polymer, polysulfone, polyethersulfone, polycarbonate, maleimide modified resin, ABS resin, acrylonitrile-acrylic rubber / styrene resin, Acrylonitrile / ethylene / propylene / diene rubber-general-purpose resins such as styrene resin, polyethylene, polypropylene, polyvinyl chloride, and polystyrene The can be exemplified.

  Next, the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
The composite particles of Example 1 were produced by the following procedure.
(1) An aqueous sodium aluminate solution was prepared by dissolving 0.37 g of sodium aluminate (manufactured by Kanto Chemical Co., Ltd.) in 150 mL of ion-exchanged water.
(2) A suspension was obtained by adding 20 g of graphite (center particle diameter 65 μm, aspect ratio 30, the same applies to graphite below) to this aqueous solution.
(3) While stirring this suspension, carbon dioxide gas was blown in at a rate of 1 L / min until the pH reached 7, to obtain a suspension containing graphite having alumina hydrate gel coated or bonded on the surface. Obtained.
(4) An aqueous solution of magnesium chloride obtained by dissolving 13.2 g of magnesium chloride (anhydride) (manufactured by Yoneyama Pharmaceutical Co., Ltd.) in 100 mL of ion-exchanged water was added to this suspension at a rate of 17 mL / min using a liquid sending pump. Was added dropwise to obtain a suspension.
(5) While stirring this suspension, an aqueous solution of sodium carbonate obtained by dissolving 6.67 g of sodium carbonate (manufactured by Tokuyama Corporation) in 55 mL of ion-exchanged water was dropped at a rate of 17 mL / min using a liquid sending pump. To give a suspension.
(6) This suspension was aged at 60 ° C. for 1 hour with stirring.
(7) The product obtained by aging is filtered, washed with water, and dried, whereby the surface of graphite is coated or bound with alumina hydrate gel, and the surface of the alumina hydrate gel is coated with basic magnesium carbonate. Alternatively, bonded high thermal conductive inorganic filler composite particles were obtained.

[Example 2]
The composite particles of Example 2 were produced in the same manner as in Example 1 except that 13.2 g of magnesium chloride (anhydride) was changed to 28 g of magnesium chloride (hexahydrate) (manufactured by Kanto Chemical Co., Ltd.).

[Example 3]
The composite particles of Example 3 were produced in the same procedure as in Example 2, except that the aging temperature was changed to 80 ° C.

[Example 4]
The composite particles of Example 4 were produced in the same procedure as in Example 2, except that the magnesium chloride aqueous solution and the sodium carbonate aqueous solution were added all at once without using a liquid sending pump instead of using a liquid sending pump.

[Example 5]
In the composite particles of Example 5, the amounts of graphite, sodium aluminate, magnesium chloride (hexahydrate) and sodium carbonate were each doubled, while the amount of ion-exchanged water of Example 2 was unchanged. The procedure was the same as that of Example 2 except that the aqueous solution and the aqueous solution of sodium carbonate were added at once without using a liquid sending pump instead of dropping by a liquid sending pump.

[Example 6]
The composite particles of Example 6 were changed except that the aging time was changed to 5 hours, and the method of adding the aqueous solution of magnesium chloride and the aqueous solution of sodium carbonate was not dripping with a liquid feed pump, but was added all at once without using a liquid feed pump. It was produced in the same procedure as in Example 2.

[Example 7]
In the composite particles of Example 7, 28 g of magnesium chloride (hexahydrate) was changed to 16.6 g of magnesium sulfate (anhydride) (manufactured by Kanto Chemical Co., Ltd.), and an aqueous solution of magnesium sulfate and an aqueous solution of sodium carbonate were added. The procedure was performed in the same manner as in Example 2 except that the method was not dripping with a liquid feed pump, but was performed at once without using a liquid feed pump.

Example 8
The composite particles of Example 8 were prepared by changing 28 g of magnesium chloride (hexahydrate) to 42 g of magnesium chloride (hexahydrate) and 6.67 g of sodium carbonate to 10 g of sodium carbonate. The solution was prepared in the same manner as in Example 2 except that the aqueous solution was not added dropwise by a liquid sending pump but was added at once without using a liquid sending pump.

[Example 9]
The composite particles of Example 9 were changed from 20 g to 10 g of graphite, 0.37 g to 0.18 g of sodium aluminate, 28 g to 56 g of magnesium chloride (hexahydrate), and 6.67 g to 13.3 g of sodium carbonate. Further, the same procedure as in Example 2 was carried out except that a magnesium chloride aqueous solution and a sodium carbonate aqueous solution were added at once without using a liquid sending pump instead of using a liquid sending pump.

[Example 10]
The composite particles of Example 10 were produced by the following procedure.
(1) An aqueous solution of sodium aluminate was obtained by dissolving 0.37 g of sodium aluminate in 150 mL of ion-exchanged water.
(2) To this aqueous solution was added 20 g of graphite to obtain a suspension.
(3) While stirring this suspension, carbon dioxide gas was blown into the suspension at a rate of 1 L / min until the pH reached 7, to obtain a suspension containing graphite having a surface coated or bonded with alumina hydrate gel. Obtained.
(4) The suspension was filtered, washed with water and dried to obtain graphite having alumina hydrate gel coated or bonded on the surface.
(5) To a magnesium chloride aqueous solution in which 7.2 g of magnesium chloride (anhydride) was dissolved in 100 mL of ion-exchanged water, 11 g of graphite having a surface coated or bound with alumina hydrate gel was added to obtain a suspension.
(6) While stirring this suspension, an aqueous solution of sodium carbonate in which 3.7 g of sodium carbonate was dissolved in 55 mL of ion-exchanged water was added dropwise at a rate of 17 mL / min using a liquid sending pump.
(7) This suspension was aged at 60 ° C. for 1 hour with stirring.
(8) By filtering, washing and drying the product obtained by aging, the surface of graphite is coated or bound with an alumina hydrate gel, and the surface of the alumina hydrate gel is coated with basic magnesium carbonate. Alternatively, bonded high thermal conductive inorganic filler composite particles were obtained.

[Example 11]
The composite particles of Example 11 were produced in the same manner as in Example 10, except that 0.37 g of sodium aluminate was changed to 1.85 g of sodium aluminate.

[Example 12]
In the composite particles of Example 12, the quantity of graphite coated or bonded with alumina hydrate gel was changed to 20 g, 7.2 g of magnesium chloride (anhydride) was changed to 28 g of magnesium chloride (hexahydrate), and The same procedure as in Example 10 was carried out, except that 3.7 g of sodium carbonate was changed to 8.7 of potassium carbonate (manufactured by Kanto Chemical Co., Ltd.).

[Example 13]
The composite particles of Example 13 were produced by the following procedure.
(1) To 2100 g of industrial alcohol (manufactured by Imazu Pharmaceutical Co., Ltd., Clean Ace High), 12.24 g of aluminum isopropoxide (manufactured by Kanto Chemical Co., Ltd.) was added and dissolved by stirring.
(2) A suspension was obtained by adding 360 g of graphite to this solution.
(3) While stirring this suspension, 6.48 g of ion-exchanged water was added dropwise to obtain a suspension containing graphite having a surface coated or bonded with alumina hydrate gel.
(4) The suspension was filtered, washed with water and dried to obtain graphite having alumina hydrate gel coated or bonded on the surface.
(5) To a magnesium chloride aqueous solution in which 28 g of magnesium chloride (hexahydrate) is dissolved in 100 mL of ion-exchanged water, 20 g of graphite having the above-mentioned alumina hydrate gel coated or bonded on the surface is added to obtain a suspension. Was.
(6) While stirring this suspension, an aqueous sodium carbonate solution in which 6.67 g of sodium carbonate was dissolved in 55 mL of ion-exchanged water was added to obtain a suspension.
(7) This suspension was aged at 60 ° C. for 1 hour with stirring.
(8) By filtering, washing and drying the product obtained by aging, the surface of graphite is coated or bound with an alumina hydrate gel, and the surface of the alumina hydrate gel is coated with basic magnesium carbonate. Alternatively, bonded high thermal conductive inorganic filler composite particles were obtained.

[Example 14]
The composite particles of Example 14 were obtained by subjecting the composite particles obtained in Example 5 to heat treatment at 300 ° C. for 8 hours using an electric furnace (HRK-354035, manufactured by Kyoei Electric Furnace Mfg. Co., Ltd.) to obtain a graphite surface. High thermal conductive inorganic filler composite particles were obtained in which alumina was coated or bonded to the surface, and the surface of the alumina was coated or bonded to basic magnesium carbonate from which water of hydration was removed.

[Comparative Example 1]
The sample of Comparative Example 1 was produced according to the following procedure. Note that the sample of Comparative Example 1 is a highly heat-conductive inorganic filler composite particle in which the surface of graphite according to the invention of Patent Document 2 is coated or bound with basic magnesium carbonate.
(1) Magnesium chloride (anhydride) (13.2 g) was dissolved in ion-exchanged water (100 mL) to prepare a magnesium chloride aqueous solution.
(2) 6.67 g of sodium carbonate was dissolved in 55 mL of ion-exchanged water to prepare an aqueous sodium carbonate solution.
(3) The sodium carbonate aqueous solution was added dropwise to the magnesium chloride aqueous solution of (1) at a rate of 17 mL / min using a liquid sending pump to form a basic magnesium carbonate gel. (4) Graphite was added to the gel solution. Was added to prepare a suspension with graphite.
(5) This suspension was aged at 60 ° C. for 1 hour with stirring.
(6) The product obtained by aging was filtered, washed with water, and dried to obtain a sample in which the surface of graphite was coated or bound with basic magnesium carbonate.

[Comparative Example 2]
The sample of Comparative Example 2 is a mixed particle of basic magnesium carbonate and graphite obtained by dry-mixing graphite and basic magnesium carbonate at a weight ratio of 4: 1.
The basic magnesium carbonate used here was prepared by reacting an aqueous solution of magnesium chloride and an aqueous solution of sodium carbonate without adding graphite as in Comparative Example 1.

[Comparative Example 3]
The sample of Comparative Example 3 was produced in the same procedure as in Example 2 except that the aging temperature was changed to 40 ° C.

[Comparative Example 4]
In the sample of Comparative Example 4, 6.67 g of sodium carbonate was changed to 10.6 g of sodium hydrogen carbonate (manufactured by Yoneyama Pharmaceutical Co., Ltd.), and sodium hydrogen carbonate was dissolved in 110 ml of ion-exchanged water. The procedure was performed in the same manner as in Example 2 except that the aqueous solution of sodium hydrogen was added at a stroke without using a liquid sending pump instead of dropping by a liquid sending pump.

[Comparative Example 5]
The sample of Comparative Example 5 was prepared in the same procedure as in Example 4 except that the order of adding the aqueous solution of magnesium chloride and the aqueous solution of sodium carbonate was reversed, and the aqueous solution of magnesium carbonate was added after the aqueous solution of sodium carbonate was added.

[Comparative Example 6]
The sample of Comparative Example 6 is a raw material graphite.

Various physical properties were examined for the composite particles of the examples and the samples of the comparative examples. That is, the graphite content of the composite particles or the sample, the content of the alumina hydrate gel, the content of the basic magnesium carbonate, the SEM image, the volume resistivity (ρ _V ), and the composite particles or the sample were mixed with the epoxy resin. The thermal conductivity of the resin sample was measured. The methods for analyzing various physical properties are as follows.

[Graphite content, alumina hydrate gel content and basic magnesium carbonate content]
Using a thermal analyzer (TG-DTA2000SA, manufactured by Bruker AXS Co., Ltd.), [Graphite content] and [Alumina hydrate] were obtained from the following formula (3) based on the weight loss rate at 600 ° C. Gel content] and [basic magnesium carbonate content] were derived.
Z = (X × W + Y × W-34.6 × Y) / (58.5-W)
T = X + Y + Z
G = X / T × 100
M = Y / T × 100
N = Z / T × 100 (3)
X: Amount of graphite used [g]
Y: Weight of composite particles and alumina hydrate gel in sample [g]
Z: Weight of basic magnesium carbonate in composite particles and sample [g]
W: Weight loss rate of composite particles and sample at 600 ° C. [wt%]
T: Weight of composite particles and sample [g]
G: Content of graphite in composite particles and sample [wt%]
M: Content of alumina hydrate gel in composite particles and sample [wt%]
N: Content of basic magnesium carbonate in composite particles and sample [wt%]
78: Molecular weight of alumina hydrate gel assuming Al (OH) ₃
102: Molecular weight of alumina
34.6: This is the theoretical value of the weight loss rate when the alumina hydrate gel is converted to alumina by heat treatment, and is expressed as “1- (molecular weight of alumina / 2 / alumina hydrate gel.
(Molecular weight assuming Al (OH) ₃ )
58.5: Assuming that the basic formula of basic magnesium carbonate is 4MgCO ₃ · Mg (OH) ₂ · 5H ₂ O
The basic magnesium carbonate was transferred to magnesium oxide by heat treatment
Theoretical weight loss rate

"The weight (g) of the alumina hydrate gel in the composite particles and the sample" of Y above or the "weight (g) of the alumina hydrate gel in the composite particles when heated at 300 ° C." Was determined by the following equation.
(A) When sodium aluminate is used to coat or bind alumina hydrate gel to graphite
Y = A × (B / 100) × 78/102/2
A: Amount of sodium aluminate used [g]
B: Al ₂ O ₃ content of sodium aluminate [wt%] (Based on the standard value, it was assumed that the Al ₂ O ₃ content of sodium aluminate used in the present invention was 36.5 wt%)
(B) When aluminum isopropoxide is used to coat or bind alumina hydrate gel to graphite
Y = C x 78 / 204.25
C: Amount of aluminum isopropoxide used [g]
78: Molecular weight of alumina hydrate gel assuming Al (OH) ₃
204.25: Molecular weight of aluminum isopropoxide (c) In the case of heat treatment of Example 14
Y '= Y × 102/2/78
Z '= Z × (W' / (WY × 34.6 / 100))
T '= X + Y' + Z '
G = X / T '× 100
M = Y '/ T' × 100
N = Z '/ T' x 100 (4)
X: Amount of graphite used [g]
Y: Weight of alumina hydrate gel of composite particles before heat treatment [g]
Y ′: weight of alumina hydrate gel when heated at 300 ° C. in the composite particles [g]
Z: Weight of basic magnesium carbonate in composite particles [g]
Z ′: weight of basic magnesium carbonate in composite particles when heated at 300 ° C. [g]
T ′: Weight of composite particles after heat treatment [g]
W: Weight loss rate of the composite particles at 600 ° C [wt%]
W ': Weight loss rate at 600 ° C of the composite particles after heat treatment at 300 ° C [wt%]
78: Molecular weight of alumina hydrate gel assuming Al (OH) ₃
102: Molecular weight of alumina
34.6: Rate of weight loss when alumina hydrate gel is transformed to alumina by heat treatment
The theoretical value is as follows: `` 1- (molecular weight of alumina / 2 / alumina hydrate gel)
(Molecular weight assuming Al (OH) ₃ )

  X, the actually measured W, and the Y obtained above were substituted into the above equation (3) to determine the “weight of basic magnesium carbonate in the composite particles and the sample [g]” of Z. Then, the “weight of composite particles and sample [g]” of T was determined from X, Y and Z based on the above equation (3), and the G content of graphite in composite particles and sample [wt% ], M “content of alumina hydrate gel in composite particles and sample [wt%]” and N “content of basic magnesium carbonate in composite particles and sample [wt%]” . In the case of the heat treatment of Example 14, Y ′ was determined from Y based on the above equation (4). Then, based on the measured W ', W, Y and Z, the "weight [g] of the basic magnesium carbonate in the composite particles when heated at 300 [deg.] C." of Z' was determined based on the formula (4). Further, the “weight of composite particles after heat treatment [g]” of T ′ was determined from X, Y ′ and Z ′, and the “content of graphite in composite particles [wt%]” of G and “composite of M” The content of alumina hydrate gel in particles [wt%] and the content of basic magnesium carbonate in composite particles [wt%] of N were derived. The results are shown in Table 1. In addition, the content rate of Table 1 may be more than 100 wt% because the second decimal place is rounded off in the calculation. Table 1 also shows the manufacturing conditions for the composite particles and the samples.

[SEM image observation]
The composite particles or the sample were stuck on a carbon tape, and the morphology of the composite particles or the sample was observed using a scanning electron microscope.
In the composite particles or the sample, the case where the graphite surface is hardly observed even when carefully observed is indicated by ○, the case where a part of the graphite surface is easily observed without careful observation is indicated by Δ, and the graphite is observed even when carefully observed. The case where only the surface was almost observed was evaluated as x, and the coating state was evaluated. The results are shown in Table 2.
The SEM images of the composite particles of Examples 1, 7, and 13, the samples of Comparative Examples 1 and 3, and the SEM images of graphite coated or bonded with alumina hydrate gel are shown in FIGS. 6 to 9. FIG. 4 shows that the particles of the basic magnesium carbonate are covered with the composite particles in a plate shape.

[Volume resistivity]
Using a hand press, 1.0 g of the composite particles or the sample was uniaxially pressed to obtain a cylindrical molded product having a diameter of 1.1 cm and a length of 0.75 cm. This molded product is sandwiched between aluminum metal plates, and while applying a load of 1.5 kg, the resistance (R) is measured using a tester (CDM-03, manufactured by Custom Co., Ltd.), and the resistance is calculated using the following equation. The volume resistivity (ρ _V ) was derived (see FIG. 11).
The volume resistivity ([rho _V) [Omega · cm] = resistance (R) [Omega] × cross-sectional area (S) [cm _2] / Length (L)
〔cm〕
= Resistance value (R) [Ω] x π (0.55) ² [cm ₂ ] /0.75 [cm]
The results are shown in Table 2.

〔Thermal conductivity〕
After mixing 10 g of composite particles or a sample with 40 g of an epoxy resin (manufactured by Mitsui Chemicals, Inc., Epomic R140P) and mixing them sufficiently, 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) was added. 0.8 g was added, mixed well, and heated and cured at 120 ° C. for 2 hours to prepare a test sample for measuring thermal conductivity. The obtained test sample for thermal conductivity measurement was cut out as a test piece of 4 cm × 4 cm × 2 cm and kept in a thermostat at 25 ° C. for 2 hours or more. Thereafter, the thermal conductivity of the resin sample containing the composite particles or the sample was measured using a rapid thermal conductivity meter (QTM-500, manufactured by Kyoto Electronics Industry Co., Ltd.). The results are shown in Table 2.

The thermal conductivity of the composite particle itself and the thermal conductivity of the sample itself were derived using the following equation (1).
λf = (λc−λm · Vm) / Vf * C (1)
(However, λf: thermal conductivity of the composite particles or the sample, λc: thermal conductivity of a resin sample in which 25 parts of the composite particles or the sample are blended with 100 parts of the resin, λm: thermal conductivity of the resin, Vf: the composite particles Or volume fraction of sample, Vm: volume fraction of resin, C: correction coefficient (10))
The parameters for deriving λf are as follows.
λc: thermal conductivity obtained in the above paragraph [0057], λm: 0.24 W / m · K (measured value), Vf: A ÷ (A + B) (A; weight of composite particles or sample in resin sample) Divided by its specific gravity (density), B; a value obtained by dividing the weight of the epoxy resin in the resin sample by its specific gravity (density) (specific gravity of composite particles and specific gravity of samples of Comparative Examples 3 to 5; 2.2). (The specific gravity of graphite is 2.2 (known), the specific gravity of basic magnesium carbonate is 2.2 (known), and the specific gravity of alumina hydrate gel is 2.5 (known). The specific gravity of the hydrate gel was set to 2.2 because the content of the hydrate gel was 0.3 wt% to 10 wt%, and the specific gravity of the sample of Comparative Examples 1 and 2 was 2.2 (the specific gravity of graphite was 2.2 ( The specific gravity of basic magnesium carbonate is 2.2 (known)), the specific gravity of the sample of Comparative Example 6; 2.2 (the specific gravity of graphite is 2.2 (known)) , The specific gravity of the epoxy resin; 1.16 (known)), Vm: B ÷ (A + B)
The results are shown in Table 2. The “thermal conductivity (measured value)” column in Table 2 is the thermal conductivity of the resin sample in which the composite particles or the sample were blended, and the “thermal conductivity (derived value)” column was defined by the formula This is the thermal conductivity of the composite particle itself or the thermal conductivity of the sample itself derived using (1). Further, for alumina, which is a general-purpose high thermal conductive filler, a resin sample in which alumina is blended with an epoxy resin is prepared, and each parameter of the formula (1) is measured and calculated, and the thermal conductivity of the alumina itself is calculated by the formula (1). ).

As can be seen from Tables 1 and 2, the volume resistivity of Example 1 was substantially the same as that of Comparative Example 1 which is the high thermal conductive inorganic filler composite particles according to the invention of Patent Document 2, although the graphite content was almost the same. The value (ρ _V ) has a value of about 25 times. This is because, by providing an intermediate layer of alumina hydrate gel having a mesh structure on the graphite surface, the thickness of the layer coated or bonded with alumina hydrate gel and basic magnesium carbonate increases, and the conductive graphite It is presumed that the insulation between the particles was maintained because the distance between the particles was maintained.
In addition, Example 9 having the lowest thermal conductivity among the examples is 71% (measured value) or 65% (derived value) as compared with Comparative Example 1 which is a highly thermally conductive inorganic filler composite particle of Patent Document 2. While having thermal conductivity, the volume resistivity (ρ _V ) of the ninth embodiment is about 215 times that of the first comparative example, which is far superior to that of the first comparative example. Further, the thermal conductivity of alumina derived from the equation (1) was 30 W / m · K, which was a numerical value substantially matching the known thermal conductivity of alumina. The derived value (58 W / m · K) of the thermal conductivity of the ninth embodiment is about 1.9 times the thermal conductivity of alumina, which is sufficiently higher than that of an existing high thermal conductive filler that is widely used. Having. Examples 2, 5, 7, and 12 have a higher thermal conductivity than Comparative Example 1, and also have an extremely higher insulating property than Comparative Example 1. In addition, it can be seen that when the GV / T value is 2.00 or more, composite particles having both high thermal conductivity and high insulation can be obtained.

  The highly heat-conductive inorganic filler composite particles of the present invention are inexpensive, have excellent insulating properties and heat conductivity, and are particularly useful in the field of electronic components such as substrates and semiconductor packages.

Claims (13)

  High thermal conductive inorganic filler composite, characterized in that the surface of graphite is coated or bonded with an alumina hydrate gel, and the surface of the alumina hydrate gel is coated or bonded with basic magnesium carbonate. particle.   High thermal conductive inorganic filler composite particles characterized in that the surface of graphite is coated or bonded with alumina, and the surface of the alumina is coated or bonded with basic magnesium carbonate from which water of hydration is removed. . The thermal conductivity measured using a thermal conductivity meter of a resin sample prepared by blending the measurement target with the epoxy resin is 0.80 W / m · K to 2.00 W / m · K. The volume resistivity (ρ _V ) derived by multiplying the resistance value measured using a tester of a molded product produced by pressurization by the cross-sectional area of the molded product and dividing by the length is 1000Ω · cm to 100000Ω · cm. The highly thermally conductive inorganic filler composite particles according to claim 1 or 2, wherein The high thermal conductive inorganic filler composite particles according to claim 1 or 2, wherein the thermal conductivity derived from the following formula (1) is 50 W / m · K to 150 W / m · K.
λf = (λc−λm · Vm) / Vf * C (1)
(However, λf: thermal conductivity of high thermal conductive inorganic filler composite particles, λc: thermal conductivity of resin sample obtained by mixing 25 parts of high thermal conductive inorganic filler composite particles with 100 parts of resin, λm: thermal conductivity of resin Ratio, Vf: volume fraction of the high thermal conductive inorganic filler composite particles, Vm: volume fraction of the resin, C: correction coefficient (10)) The high thermal conductive inorganic filler composite particles according to claim 1 or 2, wherein the following formula (2) is satisfied.
GV / T value = graphite content / 100 × volume resistivity (log .rho _V) / thermal conductivity
2.00 ≦ GV / T value ≦ 4.00 (2)
(However, the thermal conductivity is the thermal conductivity of a resin sample containing high thermal conductive inorganic filler composite particles.) The graphite content is 45 wt% to 90 wt%, the alumina hydrate gel or alumina content is 0.3 wt% to 10 wt%, and the basic magnesium carbonate content is 5 wt% to The high thermal conductive inorganic filler composite particles according to claim 1 or 2, wherein the content is 54.7% by weight.   Adding graphite to an aqueous solution of an aluminate to prepare a suspension, blowing carbon dioxide gas through the suspension to obtain graphite having alumina hydrate gel coated or bonded to the surface; A suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to graphite having a gel coated or bonded to the surface, and adding an aqueous solution of a water-soluble metal carbonate with stirring to the suspension. The method according to claim 1, further comprising: a step of heating and stirring the suspension to ripen the suspension; and a step of solid-liquid separating, washing and drying the product obtained after the aging. A method for producing the high thermal conductive inorganic filler composite particles according to the above.   A step of adding water to a suspension obtained by adding graphite to an alcohol solvent containing aluminum alkoxide to obtain graphite having alumina hydrate gel coated or bonded on the surface, and the alumina hydrate gel coated on the surface Or obtaining a suspension by adding an aqueous solution of a water-soluble metal carbonate with stirring to a suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to the bound graphite, The high thermal conductivity according to claim 1, comprising: a step of heating and stirring the suspension to ripen it; and a step of solid-liquid separating, washing with water, and drying the product obtained after ripening. A method for producing inorganic filler composite particles.   Adding graphite to an aqueous solution of an aluminate to prepare a suspension, blowing carbon dioxide gas through the suspension to obtain graphite having alumina hydrate gel coated or bonded to the surface; A suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to graphite having a gel coated or bonded to the surface, and adding an aqueous solution of a water-soluble metal carbonate with stirring to the suspension. , A step of heating and stirring the suspension to ripen it, a step of solid-liquid separation, washing with water, and a drying of the product obtained after the aging, and a heat treatment of the product obtained in the step. Removing the hydrated water of the basic magnesium carbonate coated or bound on the surface of the alumina hydrate gel by performing Method of manufacturing over the composite particles.   A step of adding water to a suspension obtained by adding graphite to an alcohol solvent containing aluminum alkoxide to obtain graphite having alumina hydrate gel coated or bonded on the surface, and the alumina hydrate gel coated on the surface Or obtaining a suspension by adding an aqueous solution of a water-soluble metal carbonate with stirring to a suspension obtained by adding an aqueous solution of a water-soluble inorganic magnesium salt or an aqueous solution of a water-soluble organic magnesium salt to the bound graphite, Heating and stirring the suspension to ripen it, solid-liquid separation of the product obtained after aging, washing with water, and drying; and heating the product obtained in the above step to obtain alumina water. Removing the water of hydration of the basic magnesium carbonate coated or bound on the surface of the hydrate gel. Method for producing a filler composite particles.   The method for producing highly thermally conductive inorganic filler composite particles according to any one of claims 7 to 10, wherein the aging temperature in the aging step is 50 ° C to 100 ° C.   The method for producing highly thermally conductive inorganic filler composite particles according to claim 9, wherein the heat treatment is heating at 250 ° C. to 400 ° C. for 0.5 to 24 hours.   A resin composition, which is filled with the high thermal conductive inorganic filler composite particles according to any one of claims 1 to 6.

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