TW202218988A - Spherical alumina powder, resin composition and heat dissiparion material - Google Patents

Abstract

The present invention provides a spherical alumina powder which is configured such that: in the particle size distribution thereof as measured by a laser diffraction/scattering particle size distribution measuring device, the maximum particle diameter indicating the maximum peak is within the range of from 35 [mu]m to 70 [mu]m; the frequency of the maximum particle diameter is from 5% to 15%; and among the respective frequencies of 20 particle diameters obtained by dividing the particle diameter range of from 1 [mu]m to 20 [mu]m into 19 equal parts, the frequencies of at least 6 particle diameters are 0.1% or more, and the cumulative frequency of the particle diameter range of from 1 [mu]m to 20 [mu]m is from 3% by volume to 17% by volume.

Description

Spherical alumina powder, resin composition, heat dissipation material

The present invention relates to spherical alumina powder, resin composition, and heat dissipation material.

In recent years, the miniaturization, thinning and narrowing of the pitch of semiconductor packages have been rapidly accelerated in response to the requirements of small size, light weight and high performance of electronic equipment. In addition, the mounting method has also become mainstream, which is surface mounting suitable for high-density mounting on wiring boards and the like. As described above, in the progress of semiconductor packages and their mounting methods, functional improvements are also required for heat-dissipating materials, and polysiloxane resins are actively filled with ceramic powders, especially spherical alumina powders, to a high degree. Research. The problem of filling the ceramic powder to a high degree is that the viscosity of the material may be increased, and the defects in the molding process may be increased.

In order to solve this point, improvement from the aspect of resin and improvement from the aspect of ceramic powder have been made. In terms of improvement in ceramic powder, there are, for example, a method of increasing Waddell's sphericity to 0.7 to 1.0 (Patent Document 1), and a straight line represented by a rosin-rammler diagram. The gradient is 0.6 to 0.95, the method of expanding the particle size distribution (Patent Document 2), the method of making the particle size distribution with several peaks in the particle size distribution to become a multimodal particle size distribution, and the method of making the ceramic powder close to the most densely packed structure (Patent Document 2) 3), etc., but it is still unsatisfactory. If the filling rate is increased, the viscosity of the material will rise sharply. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 3-066151 [Patent Document 2] Japanese Patent Application Laid-Open No. 6-080863 [Patent Document 3] Japanese Patent Laid-Open No. 8-003365

[The problem to be solved by the invention]

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide a practical spherical alumina powder exhibiting good fluidity. [Means of Solving Problems]

The inventors of the present invention, as a result of intensive studies in order to solve the above-mentioned problems, found that the above-mentioned problems can be solved by the present invention described below, and completed the present invention. That is, the present invention is as follows.

[1] A spherical alumina powder, in the particle size distribution measured by a laser diffraction scattering particle size distribution measuring machine, the maximum particle size showing the largest peak part falls in the range of 35~70 μm, the maximum particle size The frequency is 5~15%. Among the frequencies of 20 particle sizes obtained by 19 equal parts in the range of particle size 1~20μm, the frequencies of at least 6 particle sizes are respectively 0.1% or more, and the particle size is 1~20μm. The cumulative value of this frequency in the range of 20 μm is 3 to 17% by volume. [2] The spherical alumina powder according to [1], wherein the cumulative value of the frequency in the range of the particle diameter of 20 to 100 μm in the range of the peak portion having the largest peak portion is 70% by volume or more. [3] A resin composition comprising a resin and the spherical alumina powder of [1] or [2]. [4] A heat-dissipating material comprising the resin composition of [3]. [Effect of invention]

According to the present invention, a practical spherical alumina powder exhibiting good fluidity can be provided.

In the particle size distribution of the spherical alumina powder of the present invention measured by a laser diffraction scattering particle size distribution measuring machine, the maximum particle size of the largest peak part is in the range of 35-70 μm, and the maximum particle size is in the range of 35-70 μm. The frequency is 6~12%, and among the frequencies of 20 particle sizes obtained by 19 equal parts in the range of particle size 1~20μm, the frequency of at least 6 particle sizes is more than 0.1%, and the particle size is 1~20μm. The cumulative value of the frequency in the range is 3~17% by volume.

As described above, the present invention shows that the spherical alumina powder having the largest peak portion is used as the main component, and the spherical alumina powder having a smaller diameter than the spherical alumina powder is uniform in the particle size range of 1 to 20 μm. exists, whereby the effect of improving the flowability is obtained more than ever.

The reason why the above-mentioned effect of improving the fluidity can be obtained is presumed to be as follows. Generally, when the powder is densely packed, liquid crosslinking occurs between particles due to the influence of moisture in the environment. When liquid crosslinking occurs, the viscosity increases, and the fluidity when used as a resin composition decreases. Based on such a phenomenon, in the present invention, it is presumed that by uniformly presenting the spherical alumina powder having the above-mentioned small diameter in the range of particle diameter of 1 to 20 μm, the particles of the spherical alumina powder having the largest peak portion can be suppressed from being separated from the particles of the spherical alumina powder having the largest peak. The liquid crosslinks generated between the powders show high fluidity even when the powder is in a dense state. Hereinafter, an embodiment (this embodiment) of the present invention will be described in detail. [Spherical alumina powder] In the particle size distribution of the spherical alumina powder of the present embodiment measured by a laser diffraction scattering particle size distribution analyzer, the maximum particle size of the largest peak portion is in the range of 35-70 μm, and the maximum particle size is in the range of 35-70 μm. The frequency is 5~15%. If the maximum particle size is outside the above range, the rolling resistance increases, and the viscosity of the resin composition containing the spherical alumina powder increases. The maximum particle size is preferably in the range of 40 to 65 μm.

In addition, if the frequency of the maximum particle size does not fall within the range of 5 to 15%, the rolling resistance will increase, and the viscosity of the resin composition containing spherical alumina powder will increase. The frequency of the maximum particle size should be in the range of 7~11%.

In addition, the spherical alumina powder of the present embodiment is 20 particle sizes obtained by 19 equal parts in the range of particle size 1 to 20 μm (particle size of 1 μm, 2 μm, 3 μm, . . . , 20 particle diameters of 20 μm) Among the frequencies, the frequencies of at least 6 particle sizes are respectively 0.1% or more, and the cumulative value of the frequencies in the range of particle size 1~20μm is 3~15% by volume. If this condition is not met, the liquid crosslinking inhibitory effect decreases, and the viscosity of the resin composition containing the spherical alumina powder increases. Preferably, among the 20 particle sizes, the frequencies of 9 particle sizes are respectively 0.1% or more. In addition, the frequency should preferably be 0.2% or more. The upper limit of this frequency is preferably about 2%. In addition, the cumulative value of the above-mentioned frequency in the range of the particle size of 1 to 20 μm is preferably 3 to 17% by volume.

The maximum peak portion is measured by a laser diffraction scattering particle size distribution analyzer as described above, and specifically, it can be measured and calculated by the method described in the Examples.

The cumulative value of the frequency in the range of particle size 20 to 100 μm in the particle size region in the peak range with the largest peak is preferably 70% by volume or more, more preferably 75 to 90% by volume. The increase in viscosity can be prevented by the cumulative value of this frequency being 70 vol% or more.

Here, the range of the peak part having the largest peak part is the range from the particle diameter of 20 μm through the largest peak part until the frequency becomes the lowest value, and is preferably the range of the particle diameter of 20 to 100 μm. In addition, the diameter at which the frequency becomes the maximum within the above-mentioned range is the maximum particle diameter.

The average particle size of the spherical alumina powder of the present embodiment is preferably 35 to 70 μm, more preferably 40 to 50 μm. The increase in viscosity can be prevented by the average particle size being 35~70μm. Here, the above-mentioned average particle diameter is the cumulative 50% diameter (D50) on a volume basis measured by a laser diffraction scattering particle size distribution analyzer, and can be measured and calculated by the method described in the Examples.

The average sphericity of the spherical alumina powder of the present embodiment is preferably 0.9 or more, more preferably 0.92-1. The increase in viscosity can be prevented by the average sphericity being 0.9 or more. Here, the above-mentioned average sphericity can be measured and calculated by the method described in the Examples.

In addition, the specific surface area is preferably 0.1 to 0.4 m ² /g, more preferably 0.2 to 0.3 m ² /g. By setting the specific surface area to 0.1 to 0.4 m ² /g, an increase in viscosity can be prevented. Here, the above-mentioned specific surface area is a value based on the BET method, and can be measured and calculated by the BET one-point method.

The spherical alumina powder of this embodiment can be produced as follows, for example. First, the alumina raw material powder as the raw material is preferably alumina powder or aluminum hydroxide powder. Then, the alumina raw material powder having an average particle size almost the same as the desired maximum particle size is put into a high-temperature flame formed by a fuel gas such as hydrogen, natural gas, acetylene gas, propane gas, butane, LPG, etc., By melting and spheroidizing, the first spherical alumina powder was produced. Similarly, the alumina raw material powder with an average particle diameter of 1-20 micrometers was melt-spheroidized, and the 2nd spherical alumina powder was produced. In addition, the average sphericity and specific surface area of the spherical alumina powder can be adjusted by controlling at least any one of the temperature in the furnace for forming the high-temperature flame, the particle size of the alumina raw material powder, and the input amount.

Then, the particle size distribution of the first spherical alumina powder is adjusted to a desired range using a sieve, a precision air classifier, or the like. Similarly, the particle size distribution of the second spherical alumina powder is adjusted to a desired range using a sieve, a precision air classifier, or the like. The desired range at this time means that among the frequencies of 20 particle diameters obtained by performing 19 equal parts in the range of particle diameters of 1 to 20 μm, the frequencies of at least 6 particle diameters are in the range of 0.1% or more, respectively, exhibiting the largest peak. The maximum particle size of the part is in the range of 35~70μm, and the frequency of the maximum particle size is in the range of 6~12%, etc. In addition, the shape of the peak portion of the particle size distribution can be sharpened or widened by adjusting the feed amount in the precise air classification, etc.

[Resin composition, heat dissipation material] The resin composition of the present invention contains the resin and the alumina powder of the present invention as described above. Furthermore, the heat-dissipating material of the present invention contains the resin composition of the present invention as described above.

As the resin, for example, silicone resin, epoxy resin, phenolic resin, melamine resin, urea-formaldehyde resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide can be used Polyamides such as imines, polyesters such as polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, wholly aromatic polyesters, polystilbene, liquid crystal polymers, polyethers Polycarbonate, polycarbonate, maleimide modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber-styrene) resin, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin, etc.

Among them, the resin used for the heat-dissipating material is preferably a polysiloxane resin, preferably at least one of an addition reaction type polysiloxane resin and a condensation reaction type polysiloxane resin. In addition, according to demand, a part of the polysiloxane resin can also be replaced with polysiloxane rubber. The polysiloxane rubber is preferably at least one of an addition reaction type polysiloxane rubber and a peroxide vulcanized type polysiloxane rubber. Any of these polysiloxane resins and polysiloxane rubbers is preferably an average composition formula of R ¹ _n SiO _(4-n)/2 (wherein R ¹ is the same or different unsubstituted Or a substituted monovalent hydrocarbon group, n is a positive number from 1.98 to 2.02.) The organopolysiloxane represented by the main component.

Specific examples of the polysiloxane resin include a one-liquid type polysiloxane having both a vinyl group and an H-Si group in one molecule, or an organopolysilicon having a vinyl group at the terminal or side chain. 2-liquid type polysiloxane of oxane, etc. Commercially available products include "XE14-8530", "TSE-3062", "YE5822", and the like, manufactured by Toshiba Silicones Ltd., for example.

The resin composition or heat-dissipating material of the present invention can be mixed with the following components according to requirements. That is, as the stress reducing agent, rubber-like substances such as polysiloxane rubber, polysulfide rubber, acrylic rubber, butadiene-based rubber, styrene-based block copolymer or saturated elastomer, various Thermoplastic resins, and resins obtained by modifying part or all of epoxy resins and phenolic resins with amino polysiloxane, epoxy polysiloxane, alkoxy polysiloxane, etc. Silane coupling agents include epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, aminopropyl Amino silanes such as triethoxysilane, ureidopropyltriethoxysilane, phenylaminosilane, N-phenylaminopropyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethyl Hydrophobic silane compounds such as oxysilane, octadecyltrimethoxysilane, or mercaptosilane, etc. As a surface treatment agent, a Zr chelate compound, a titanate coupling agent, an aluminum type coupling agent, etc. are mentioned. The flame retardants include halogenated epoxy resins, phosphorus compounds, and the like, and the colorants include carbon black, iron oxides, dyes, pigments, and the like. As the flame retardant auxiliary, Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ and the like can be mentioned. The release agent includes natural waxes, synthetic waxes, metal salts of straight-chain fatty acids, amides, esters, paraffin waxes, and the like.

The content of the spherical alumina powder of the present invention in the resin grease product or in the heat dissipation material is preferably 50 to 95% by mass. By being in the said range, desired heat resistance, moldability, etc. can be obtained.

A product obtained by mixing predetermined amounts of the above-mentioned materials with a stirrer, or a Henschel mixer, etc., and then kneading with a heated roll, a kneader, a one-shaft or two-shaft extruder, etc. After cooling, it is appropriately pulverized, whereby the resin composition or the heat dissipating material of the present embodiment can be produced.

In addition, when forming a resin composition or a heat-dissipating material, by subjecting the spherical alumina powder of the present invention to the surface treatment such as the silane coupling agent described above, the water absorption rate of the powder can be reduced, and the resin composition can be made high in strength It can further reduce the interface resistance between the resin and the powder and further improve the thermal conductivity.

In addition, the heat dissipating material of the present embodiment is preferably a thin molded body such as a sheet shape, and the processing method thereof may include conventionally known methods such as doctor blade method, coating or extrusion by a Comma coater. law, etc. The thickness of the sheet-shaped heat-dissipating material should preferably be 0.3mm or more. [Example]

Hereinafter, the present invention will be described in more detail using Examples and Comparative Examples, but the present invention is not limited to the following Examples without departing from the gist thereof.

[Example 1] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 46 μm.

(Production of the second spherical alumina powder) The alumina powder was put into the flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm. In addition, the measurement of the average particle diameter and the average sphericity was carried out as follows (the same applies to the following Examples and Comparative Examples).

(Measuring method of average particle size) The average particle diameter (volume basis) of the spherical alumina powder was measured by a laser diffraction scattering method (Microtrac (manufactured by Nikkiso, trade name "MT3300EX II")).

(Measuring method of average sphericity) The average sphericity of the spherical alumina powder was measured as follows using a flow particle image analyzer under the trade name "FPIA-3000" manufactured by Sysmex Corporation. The projected area (A) and perimeter (PM) of the particles were measured from the particle images. Taking the area of the true circle corresponding to the perimeter (PM) as (B), the sphericity of the particle can be expressed as A/B. Therefore, if a true circle with the same perimeter as the perimeter (PM) of the sample particle is assumed, then from PM=2πr, B=πr ² , B=π×(PM/2π) ² can be obtained, and the sphericity of each particle can be expressed as Circularity=A/B=A×4π/(PM) ² to calculate. 100 or more particles were randomly selected and measured, and the square of the average value was taken as the average sphericity. The measurement solution was prepared by adding 0.1 g of the sample to 20 ml of distilled water and 10 ml of propylene glycol, and performing ultrasonic dispersion treatment for 3 minutes.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 5:95 to prepare the spherical alumina powder of Example 1 (average particle size 45 μm, specific surface area 0.2 m ² / g). The particle size distribution (particle size and frequency) of the spherical alumina powder of Example 1 was measured by the laser diffraction scattering method. In the measurement, the already described Microtrac was used as a particle size distribution analyzer. The results are shown in Table 1 below.

The obtained spherical alumina powder was put into vinyl group-containing polymethylsiloxane (manufactured by Momentive Performance Materials Japan LLC, trade name YE5822A) so as to be 65% by volume (88.1% by mass) in the resin composition. After the liquid), stirring and defoaming treatment were performed to prepare a resin composition for viscosity measurement. The measurement was performed at a temperature of 30° C. using a Brookfield viscometer (trade name “TVB-10” manufactured by Toki Sangyo Co., Ltd.). The results are shown in Table 1. In addition, the viscosity should preferably be 100 Pa･s or less.

[Example 2] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 45 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 15:85 to prepare the spherical alumina powder of Example 2 (average particle size 40 μm, specific surface area 0.3 m ² / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Example 3] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 43 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 5:95 to prepare the spherical alumina powder of Example 3 (average particle size: 43 μm, specific surface area: 0.2 m ² / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Example 4] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 55 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 7 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 15:85 to prepare the spherical alumina powder of Example 4 (average particle size 52 μm, specific surface area 0.3 m ² / g). A graph showing the particle size distribution of the spherical alumina powder of Example 4 is shown in FIG. 1 .

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Example 5] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 38 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 15:85 to prepare the spherical alumina powder of Example 5 (average particle size: 36 μm, specific surface area: 0.2 m ^{2 )} . /g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Example 6] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 57 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 5:95 to obtain the spherical alumina powder of Example 6 (average particle size 55 μm, specific surface area 0.2 m ² /g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Example 7] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 50 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 10:90 to prepare the spherical alumina powder of Example 7 (average particle size 44 μm, specific surface area 0.2 m ² / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Example 8] (Production of the first spherical alumina powder) The alumina powder was put into the flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 57 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 20:80 to obtain the spherical alumina powder of Example 8 (average particle size 52 μm, specific surface area 0.2 m ^{2 )} /g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Comparative Example 1] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 55 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 20:80 to prepare a spherical alumina powder of Comparative Example 1 (average particle size 50 μm, specific surface area 0.2 m ³ / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Comparative Example 2] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 46 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 2:98 to obtain the spherical alumina powder of Comparative Example 2 (average particle size 46 μm, specific surface area 0.1 m ^{3 )} /g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Comparative Example 3] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 46 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 20:80 to obtain the spherical alumina powder of Comparative Example 3 (average particle size 42 μm, specific surface area 0.4 m ^{3 )} /g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Comparative Example 4] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 32 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 10:90 to prepare a spherical alumina powder of Comparative Example 4 (average particle size: 30 μm, specific surface area: 0.3 m ³ / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Comparative Example 5] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 61 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 5:95 to prepare a spherical alumina powder of Comparative Example 5 (average particle size 60 μm, specific surface area 0.2 m ³ / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the resin composition was obtained, and the viscosity was measured. The results are shown in Table 1 below.

[Comparative Example 6] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 45 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 15:85 to prepare spherical alumina powder of Comparative Example 6 (average particle size: 43 μm, specific surface area: 0.2 m ² / g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Comparative Example 7] (Production of the first spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 47 μm.

(Production of the second spherical alumina powder) The alumina powder was put into a flame formed by LPG and oxygen, and after spheroidizing, the cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 10 μm.

The first spherical alumina powder and the second spherical alumina powder were mixed in a volume ratio of 15:85 to obtain the spherical alumina powder of Comparative Example 7 (average particle size 45 μm, specific surface area 0.2 m ^{3 )} /g).

Using this spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the viscosity of the produced resin composition was measured. The results are shown in Table 1 below.

[Table 1] Example Comparative example 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 Maximum particle size (μm) 48 52 44 57 40 64 52 57 57 48 48 34 74 52 57 Frequency of maximum particle size (%) 11 10 11 7 7 10 6 11 8 11 7 7 10 4 16 Among the frequencies of 20 particle sizes obtained by performing 19 equal parts in the range of particle size 1~20 μm, the frequency is the number of particle sizes with a frequency of 0.1% or more 6 17 8 18 17 7 13 9 4 6 17 17 9 16 8 Among the frequencies of 20 particle sizes obtained by performing 19 equal parts in the range of particle size 1~20μm, the frequency is the number of particle sizes with a frequency of 0.2% or more 5 16 7 17 16 6 12 8 4 5 16 16 7 15 7 Cumulative value of frequency in the range of particle size 1~20μm (volume %) 6 12 3 14 10 6 11 5 3 1 18 8 5 14 4 Cumulative value (volume %) of the frequency of the particle size region corresponding to the largest peak 90 68 95 79 87 89 83 90 77 98 69 85 87 70 91 Viscosity (Pa･s) 86 89 90 88 91 80 90 86 101 103 102 108 101 106 102 [industrial applicability]

The spherical alumina powder of the present invention is suitably used as a filler for a thermally conductive resin composition. In addition, the resin composition of the present invention is used as a heat-dissipating member for heat countermeasures for computers, automobiles, mobile electronic equipment, household electrical appliances, and the like.

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[ FIG. 1 ] A graph showing the particle size distribution of the spherical alumina powder of Example 4. [ FIG.

Claims (4)

A spherical alumina powder, in the particle size distribution measured by a laser diffraction scattering particle size distribution measuring machine, the maximum particle size showing the largest peak part falls in the range of 35~70μm, and the frequency of the maximum particle size is 5~15%, Among the frequencies of 20 particle sizes obtained by performing 19 equal parts in the particle size range of 1~20μm, the frequencies of at least 6 particle sizes are respectively 0.1% or more, and the cumulative frequency of the particle size range of 1~20μm The value is 3 to 17% by volume. The spherical alumina powder according to claim 1, wherein the cumulative value of the frequency in the range of the particle diameter of 20 to 100 μm in the range of the peak portion having the largest peak portion is 70% by volume or more. A resin composition comprising a resin and the spherical alumina powder according to claim 1 or 2. A heat-dissipating material containing the resin composition of claim 3.

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