WO2024029464A1 - Alumina powder, resin composition and method for producing alumina powder - Google Patents

Alumina powder, resin composition and method for producing alumina powder Download PDF

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WO2024029464A1
WO2024029464A1 PCT/JP2023/027779 JP2023027779W WO2024029464A1 WO 2024029464 A1 WO2024029464 A1 WO 2024029464A1 JP 2023027779 W JP2023027779 W JP 2023027779W WO 2024029464 A1 WO2024029464 A1 WO 2024029464A1
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alumina
particles
alumina powder
less
particle size
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PCT/JP2023/027779
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French (fr)
Japanese (ja)
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篤 中山
祥太 榊
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住友化学株式会社
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/021—After-treatment of oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds

Definitions

  • the present disclosure relates to alumina powder, a resin composition, and a method for producing alumina powder.
  • thermally conductive member for heat radiation As one of the above thermally conductive members, there is a thermally conductive resin composition containing a resin and inorganic particles, and alumina particles are used as the inorganic particles.
  • thermally conductive member for heat dissipation
  • a thermally conductive member with a thin film thickness for example, a thermally conductive member with a film thickness on the order of tens of microns, or even on the level of several microns.
  • thermally conductive members are also required to exhibit higher thermal conductivity.
  • Patent Document 1 when a large amount of alumina particles shown in Patent Document 1 are blended into a resin, the alumina particles tend to aggregate, and coarse particles tend to occur in the resin composition. As a result, it is difficult to achieve high thermal conductivity, and it is also difficult to make the thermally conductive member thin.
  • the present disclosure has been made in view of the above circumstances, and aims to provide an alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a thermally conductive material containing the alumina powder. It is an object of the present invention to provide a resin composition that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a method for producing the alumina powder.
  • Aspect 1 of the present invention is An alumina powder having alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m,
  • the cumulative particle size D10 of 10% from the fine particle side of the number-based cumulative particle size distribution is less than 0.15 ⁇ m,
  • the above D10, the cumulative particle size D100 of 100% from the fine particle side of the number-based cumulative particle size distribution, and the cumulative particle size D50 of 50% from the fine particle side of the number-based cumulative particle size distribution satisfy the following formula (1).
  • the particle ratio (Na/Nb) of the number of alumina particles Na with an equivalent circle diameter of less than 0.3 ⁇ m and the number Nb of alumina particles with an equivalent circle diameter of 0.3 ⁇ m or more was determined.
  • the alumina powder has a coefficient of variation (CV (Na/Nb)) of 0.3 or less. 4.0 ⁇ (D100-D10)/D50 ⁇ 20...(1)
  • Aspect 2 of the present invention is The alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m are the alumina powder according to aspect 1, wherein the average circularity is 0.82 or more.
  • Aspect 3 of the present invention is The alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m are the alumina powder according to aspect 1 or 2, wherein the alumina particles are ⁇ -alumina particles.
  • Aspect 4 of the present invention is A resin composition comprising the alumina powder according to any one of aspects 1 to 3 and a resin.
  • Aspect 5 of the present invention is The resin composition according to aspect 4, wherein the mass ratio of the alumina powder to the resin is in the range of 85:15 to 95:5.
  • Aspect 6 of the present invention is a raw material preparation step of preparing a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 ⁇ m and alumina raw material particles with an equivalent circle diameter of 0.3 ⁇ m or more;
  • the method for producing alumina powder includes a mixing step of mixing the blended raw materials using a high-speed mixer with a rotation speed of 10,000 rpm or more.
  • an alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a resin composition that includes the alumina powder and has high thermal conductivity and can realize a thin film-like thermally conductive member. and a method for producing the alumina powder.
  • FIG. 1 is a SEM photograph of alumina raw material particles 2 used in Examples.
  • FIG. 2 is a SEM photograph of the alumina raw material particles 5 used in the examples.
  • FIG. 3 is a diagram showing the volume-based particle size distribution of alumina raw material particles 2 and alumina raw material particles 5 used in Examples, as measured by a laser diffraction/scattering type particle size distribution measuring device.
  • FIG. 4 is a diagram showing an example of the binarization process performed in the example.
  • FIG. 5 is a SEM image of the cross-sectional sample of Example 1.
  • FIG. 6 is another SEM image of the cross-sectional sample of Example 1.
  • FIG. 7 is a SEM image of a cross-sectional sample of Comparative Example 1.
  • FIG. 8 is another SEM image of the cross-sectional sample of Comparative Example 1.
  • FIG. 9 is a SEM image of a cross-sectional sample of Comparative Example 3.
  • the present inventors have developed an alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a resin composition containing the alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member.
  • alumina powder has alumina particles with an equivalent circle diameter of less than 0.3 ⁇ m, and from the fine particle side of the cumulative particle size distribution based on number, the cumulative particle size of 10% is D10, and the cumulative particle size of 50% is D10.
  • D50 when the cumulative 100% particle size is D100, the range of D10 is defined, D10, D50 and D100 satisfy a predetermined formula, and when observed under predetermined conditions, the dispersion state of alumina particles CV (Na / It has been found that it is sufficient if Nb) is below a certain level.
  • the alumina powder, the resin composition containing the alumina powder, and the method for producing the alumina powder according to the present embodiment will be described in detail in order.
  • the alumina powder according to the present embodiment contains alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m (hereinafter sometimes referred to as “small alumina particles”).
  • the alumina powder according to this embodiment includes small alumina particles and has an equivalent circle diameter of 0.3 ⁇ m or more (hereinafter sometimes referred to as "large alumina particles") within a range that satisfies the specified particle size distribution described below. ) may also be included.
  • the lower limit of the equivalent circle diameter of the alumina small particles may be, for example, 0.01 ⁇ m.
  • the upper limit of the equivalent circle diameter of the large alumina particles may be 3 ⁇ m or less.
  • the alumina powder according to the present embodiment has a cumulative particle size D10 (hereinafter sometimes simply referred to as "D10") of 10% from the fine particle side of the number-based cumulative particle size distribution of less than 0.15 ⁇ m. Since the alumina powder contains fine alumina particles with a particle size of less than 0.15 ⁇ m, the alumina fine particles exist in the gaps formed between large alumina particles, making it easy to achieve high filling. It is possible to improve thermal conductivity. Moreover, the presence of the fine alumina particles on the surface of relatively large alumina particles also improves the fluidity of the alumina powder in the resin when producing a resin composition.
  • the above D10 is preferably 0.10 ⁇ m or less. In addition, from the viewpoint of fluidity during mixing of the resin composition, the lower limit of the above D10 may be about 0.01 ⁇ m.
  • the alumina powder according to the present embodiment has the above-mentioned D10, a cumulative particle size D100 of 100% from the fine grain side of the number-based cumulative particle size distribution, and a cumulative particle size D50 of 50% from the fine grain side of the number-based cumulative particle size distribution. satisfies the following formula (1).
  • (D100-D10)/D50 in the following formula (1) may be referred to as a "span value.” 4.0 ⁇ (D100-D10)/D50 ⁇ 20...(1)
  • the above span value is an index indicating the spread of the particle size distribution.
  • the span value is less than 4.0, the difference between the particle diameters of the small alumina particles and the large alumina particles becomes small.
  • the particle size of the small alumina particles is close to the particle size of the large alumina particles, it becomes difficult to fill the gaps formed between the relatively large alumina particles with the alumina fine particles.
  • the particle size of the large alumina particles is close to the particle size of the small alumina particles, most of the alumina powder is occupied by particles with relatively small particle sizes, resulting in excellent thermal conductivity and good properties. It becomes difficult to secure liquidity.
  • the span value is preferably 4.1 or more, more preferably 4.3 or more, even more preferably 5.3 or more.
  • the span value exceeds 20
  • the particle size (D50) of the relatively large alumina particles will be 5 ⁇ m or more.
  • the span value is preferably 15 or less, more preferably 12 or less, still more preferably 6.3 or less, and most preferably 6.0 or less.
  • the alumina powder according to the present embodiment is observed at least 5 fields of view at a magnification of 10,000 times, the number Na of alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m, and the number Na of alumina particles having an equivalent circle diameter of 0.3 ⁇ m or more.
  • CV (Na/Nb), which is the coefficient of variation of the particle ratio with Nb (Na/Nb) satisfies 0.3 or less.
  • the alumina powder according to the present embodiment provides a resin composition in which the alumina powder has high dispersibility and the generation of agglomerated particles is suppressed. As a result, the thermal conductivity becomes high, and a thin film-like thermally conductive member can be realized.
  • the equivalent circle diameter is less than 0.3 ⁇ m as an evaluation index of the dispersibility of alumina powder.
  • CV (Na/Nb) is used, which is the coefficient of variation of the particle ratio (Na/Nb) between the number Na of alumina particles having a circular equivalent diameter of 0.3 ⁇ m or more and the number Nb of alumina particles having an equivalent circle diameter of 0.3 ⁇ m or more.
  • the coefficient of variation CV (Na/Nb) is determined by observing at least 5 visual fields at a magnification of 10,000 times.
  • the coefficient of variation CV (Na/Nb) may be evaluated using a scanning electron microscope.
  • the rotation speed is 10,000 rpm or more. It is important to mix using a high speed mixer.
  • the coefficient of variation CV (Na/Nb) is preferably 0.25 or less, more preferably 0.20 or less.
  • the average circularity of the alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m is 0.82 or more.
  • the alumina small particles have a high degree of circularity, so that the fluidity can be further improved when mixed and kneaded with the resin.
  • the average circularity of the alumina small particles is more preferably 0.85 or more, and the higher the average circularity of the alumina small particles is, the more preferable it is, but if it is 0.95 or less, equivalent fluidity can be ensured.
  • the alumina particles having an equivalent circle diameter of less than 0.3 ⁇ m are preferably ⁇ -alumina particles.
  • FIB focused ion beam
  • the crystal structure of alumina particles having an equivalent circle diameter of 0.3 ⁇ m or more is not limited.
  • it may be one or more of ⁇ alumina, ⁇ alumina, ⁇ alumina, and ⁇ alumina.
  • the alumina particles having an equivalent circle diameter of 0.3 ⁇ m or more are also ⁇ -alumina particles.
  • the method for producing alumina powder according to this embodiment is as follows: a raw material preparation step of preparing a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 ⁇ m and alumina raw material particles with an equivalent circle diameter of 0.3 ⁇ m or more; and a mixing step of mixing the blended raw materials using a high-speed mixer with a rotation speed of 10,000 rpm or more.
  • a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 ⁇ m and alumina raw material particles with an equivalent circle diameter of 0.3 ⁇ m or more is prepared, but the method for producing these alumina raw material particles is not particularly limited. For example, commercially available products can be used. Alternatively, it can be manufactured by a conventionally known method.
  • the average circularity of the alumina raw material particles having an equivalent circle diameter of less than 0.3 ⁇ m is 0.82 or more.
  • the average circularity of the alumina raw material particles having an equivalent circular diameter of less than 0.3 ⁇ m is more preferably 0.85 or more, and is preferably as high as possible, but may be 0.95 or less.
  • the average circularity of the alumina raw material particles having an equivalent circle diameter of 0.3 ⁇ m or more is not particularly limited.
  • the alumina raw material particles having an equivalent circle diameter of less than 0.3 ⁇ m are preferably ⁇ -alumina raw material particles.
  • Examples of the alumina raw material particles having an equivalent circle diameter of 0.3 ⁇ m or more include alumina raw material particles composed of one or more of ⁇ alumina, ⁇ alumina, ⁇ alumina, and ⁇ alumina. From the viewpoint of obtaining alumina powder with high thermal conductivity, it is preferable that the alumina raw material particles having an equivalent circle diameter of 0.3 ⁇ m or more are also ⁇ alumina raw material particles.
  • alumina raw material particles with an equivalent circle diameter of less than 0.3 ⁇ m and alumina raw material particles with an equivalent circle diameter of 0.3 ⁇ m or more are mixed.
  • the ratio (mass ratio) is preferably 40:60 to 10:90, for example.
  • the blended raw materials may contain a silane coupling agent, a dispersant, etc. for the purpose of improving fluidity during mixing.
  • alumina powder in which (Na/Nb) satisfies the above range.
  • alumina powder in which (Na/Nb) satisfies the above range.
  • the high-speed mixer whose rotational speed is 10,000 rpm or more is a device that mixes powder at a high-speed rotation of 10,000 rpm or more, and includes, for example, a batch type mill and a rotor speed mill.
  • common mixing devices used for mixing powders such as air blenders, rocking blenders, Henschel mixers (all with rotation speeds of 470 to 5,400 rpm), and planetary stirring mixers (with rotation speeds of 2,000 rpm or less)
  • agglomerated particles of small alumina particles with an equivalent circle diameter of less than 0.3 ⁇ m can be broken up and dispersed on the surface of primary particles of alumina raw material particles with an equivalent circle diameter of 0.3 ⁇ m or more. Furthermore, reagglomeration of alumina raw material particles having an equivalent circle diameter of 0.3 ⁇ m or more is prevented, and as a result, an alumina powder having a coefficient of variation CV (Na/Nb) satisfying the above range is obtained.
  • the resin composition according to this embodiment includes the alumina powder according to this embodiment and a resin.
  • a resin composition (composite) with high thermal conductivity can be obtained.
  • the proportion (blending ratio) of the alumina powder according to the present embodiment contained in the resin composition is preferably 40 volume% or more, more preferably 50 volume% or more. It is. On the other hand, from the viewpoint of ensuring the flexibility peculiar to the resin, the proportion of the alumina powder is preferably 90% by volume or less, more preferably 85% by volume or less.
  • the resin composition according to the present embodiment is preferably highly filled with alumina powder and can exhibit higher thermal conductivity.
  • a preferred embodiment of the resin composition highly filled with alumina powder is that the mass ratio of the alumina powder to the resin is in the range of 85:15 to 95:5.
  • the resin used in the resin composition can be selected from thermoplastic resins, thermoplastic elastomers, and thermosetting resins.
  • one type of resin may be used alone, or two or more types may be used in combination.
  • Thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinyl Acetal, fluorine-based polymers such as polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer (ABS) ) resins, polyphenylene-ether copolymer (PPE) resins, modified PPE resins, aliphatic polyamides, aromatic polyamides, polyimides, polyamide-imides, polymeth
  • thermoplastic elastomers examples include styrene-butadiene block copolymers or hydrogenated products thereof, styrene-isoprene block copolymers or hydrogenated products thereof, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and vinyl chloride-based thermoplastic elastomers. , polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, and the like.
  • thermosetting resin examples include crosslinked rubber, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, and the like.
  • crosslinked rubber examples include natural rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene rubber, Examples include chlorosulfonated polyethylene rubber, butyl rubber, halogenated butyl rubber, fluororubber, urethane rubber, and silicone rubber.
  • polyolefin resins acrylic resins, polyimide resins, polyamide resins, polyamideimide resins, epoxy resins, phenol resins, and silicone resins are preferably used.
  • these resin compositions may contain plasticizers, curing accelerators, coupling agents, fillers, pigments, flame retardants, antioxidants, surfactants, Known additives such as a compatibilizer, a weathering agent, an anti-blocking agent, an antistatic agent, a leveling agent, and a mold release agent may be used alone or in combination of two or more.
  • a resin composition can be obtained by mixing the alumina powder and resin according to this embodiment.
  • the resin when the resin is liquid (e.g., liquid epoxy resin), the resin composition can be obtained by mixing the liquid resin, alumina powder, and a curing agent, and then curing with heat or ultraviolet rays.
  • the curing agent, mixing method, and curing method known ones and methods can be used.
  • the resin if the resin is solid (for example, polyolefin resin or acrylic resin), the desired resin composition can be obtained by mixing the alumina powder and resin and then kneading them using a known method such as melt kneading. I can do it.
  • aspects of the resin composition according to the present embodiment include a mixture of alumina powder and a resin-containing raw material, a mixture of alumina powder and a resin-containing raw material, a molded product formed from the mixture, a mixture, or a molded product. It includes a molded body (cured product) obtained by, for example, curing treatment.
  • One form of the resin composition according to the present embodiment is a thin film resin composition, and another example thereof is a thin film resin composition with a film thickness of, for example, 10 ⁇ m or less, and further 5 ⁇ m or less. .
  • Alumina raw material particles 1 to 5 described below were prepared as alumina raw material particles.
  • the crystal phase of each raw material particle was determined by analyzing the crystal structure using an X-ray diffraction method.
  • particle size is a volume-based median diameter measured with a laser diffraction/scattering particle size distribution measuring device (Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.), and is distinguished from the above-mentioned D50. .
  • Allumina raw material particles 1 Product name: AA-07 (manufactured by Sumitomo Chemical Co., Ltd.), particle size: 0.9 ⁇ m, crystal phase: ⁇ alumina (Alumina raw material particles 2) Development product 1 (manufactured by Sumitomo Chemical Co., Ltd.), grains Diameter: 0.15 ⁇ m, crystal phase: ⁇ alumina (alumina raw material particles 3) developed product 2 (manufactured by Sumitomo Chemical Co., Ltd.), particle size: 0.10 ⁇ m, crystal phase: ⁇ alumina (alumina raw material particles 4) product name: ASFP -20 (manufactured by Denka Co., Ltd.), particle size: 0.3 ⁇ m, crystal phase: ⁇ alumina and ⁇ alumina (alumina raw material particles 5) product name: AKP-53 (manufactured by Sumitomo Chemical Co., Ltd.), particle size: 0.17 ⁇ m , Crystal phase: ⁇ alumina (Alumina raw material
  • the alumina raw material particles 2 were manufactured as follows. First, a seed crystal ( ⁇ alumina) slurry was prepared. Specifically, alumina particles (raw material for seed crystals) were dispersed in water, and then wet-pulverized using a ball mill to obtain a wet-pulverized product. Thereafter, the wet pulverized product was centrifuged at a rotation speed of 4000 rpm for 30 minutes to remove precipitates to obtain a seed crystal slurry in which seed crystals were dispersed. Next, the seed crystal slurry and aluminum isopropoxide were mixed at high speed and hydrolyzed to obtain an aluminum hydroxide slurry.
  • a seed crystal ( ⁇ alumina) slurry was prepared. Specifically, alumina particles (raw material for seed crystals) were dispersed in water, and then wet-pulverized using a ball mill to obtain a wet-pulverized product. Thereafter, the wet pulverized product was centrifuged at a rotation speed of
  • the obtained aluminum hydroxide slurry was dried at 150°C to obtain aluminum hydroxide particles.
  • the aluminum hydroxide particles were fired in a gas furnace at 965° C. to obtain alumina raw material particles 2.
  • the alumina raw material particles 3 (developed product 2) were obtained by changing the blending ratio of the aluminum isopropoxide and the seed crystal slurry in the manufacturing method of the alumina raw material particles 2 (developed product 1).
  • FIGS. 1 and 2 SEM photographs of alumina raw material particles 2 and alumina raw material particles 5 used in this example are shown in FIGS. 1 and 2, respectively. Further, the volume-based particle size distribution of these raw material particles is shown in FIG. 3, as measured by a laser diffraction/scattering particle size distribution measuring device (Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.).
  • a laser diffraction/scattering particle size distribution measuring device Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.
  • alumina raw material particles 1 to 5 and a silane coupling agent (trade name: OFS-6040)
  • the amounts were blended in Examples 1 to 3 and Comparative Examples 1 to 3, as shown in Table 1.
  • a blended raw material was obtained.
  • the raw materials were mixed with a high speed mixer or mixed with planetary stirring to obtain alumina powder.
  • high-speed mixer mixing mixing was performed for 30 seconds using a batch type mill (A10 manufactured by IKA, rotation speed: 20,000 rpm) to obtain a mixed powder as alumina powder.
  • planetary stirring mixing mixing was performed for 30 seconds using an autorotation/revolution mixer (ARV-310, rotation speed 2000 rpm) to obtain a mixed powder as alumina powder.
  • ARV-310 autorotation/revolution mixer
  • the particle size distribution of the alumina powder was measured as described below.
  • the obtained molded body was polished using a cross section polisher (registered trademark, SM-09010 manufactured by JEOL Ltd.) using an ion beam at an acceleration voltage of 6.0 kV for 12 hours, and a cross-sectional sample was obtained. I got it.
  • a cross section polisher registered trademark, SM-09010 manufactured by JEOL Ltd.
  • the obtained cross-sectional sample was fixed on a carbon tape, and an SEM image was taken using a scanning electron microscope (SEM, manufactured by Hitachi High-Technologies Corporation, product number: S-4800) at a predetermined acceleration voltage of 20,000 Double SEM images were acquired.
  • SEM scanning electron microscope
  • the obtained SEM image was then automatically binarized using image analysis software (ImageJ) to obtain an image in which particles were extracted.
  • FIG. 4 shows that the binarized image shown in FIG. 4B is obtained by binarizing the SEM image in FIG. 4A. Note that particles that protrude from the analysis range were excluded from the analysis target.
  • the coefficient of variation CV (Na/Nb) of the particle ratio (Na/Nb) between the number of particles Na with an equivalent circle diameter of less than 0.3 ⁇ m and the number Nb of particles with an equivalent circle diameter of 0.3 ⁇ m or more is determined by the following method. Ta.
  • Na/Nb was measured in 5 visual fields, and the average value, standard deviation, and coefficient of variation CV of Na/Nb were determined. Na/Nb of each field of view was determined, and the average value and standard deviation of Na/Nb of multiple fields of view were determined. Then, the standard deviation of the particle ratio (Na/Nb) was divided by the average value of the particle ratio (Na/Nb) to obtain the coefficient of variation CV (Na/Nb) of the particle ratio (Na/Nb). The results are shown in Table 2.
  • the coefficient of variation CV (Na/Nb) was evaluated in a state where the obtained alumina powder was mixed with a small amount of resin, but the evaluation results were the same as in the state where no resin was present. This is considered to indicate the state of dispersion. In other words, the above measurement results can be said to indicate the dispersion state of the alumina powder.
  • FIGS. 5 and 6 SEM images of the cross-sectional sample of Example 1 are shown in FIGS. 5 and 6.
  • FIGS. 7 and 8 show SEM images of a cross-sectional sample of Comparative Example 1, in which the alumina raw material particles were the same as those in Example 1 but the mixing method was different.
  • a SEM image of a cross-sectional sample of Comparative Example 3 is shown in FIG. In these photographs, the black parts indicate resin.
  • the area surrounded by the white broken line in FIGS. 7 and 8 indicates the area where aggregated particles are generated.
  • FIG. 9 only alumina raw material particles 1 are used as the alumina powder, and gaps between large alumina particles are not filled.
  • the gap between the large alumina particles derived from alumina raw material particle 1 is different from that of alumina raw material particle 2. Filled with alumina small particles.
  • Example 1 the shape of the alumina powder is within the range specified in this embodiment, so the thermal conductivity is high and there are no coarse particles of 10 ⁇ m or more, realizing a thin film-like thermally conductive member. can.
  • Comparative Example 1 the coefficient of variation CV (Na/Nb) was high, coarse particles of 10 ⁇ m or more were present, the viscosity was so high that it could not be measured, and the thermal conductivity was also low. Furthermore, since coarse grains of 10 ⁇ m or more were present, a thin film-like thermally conductive member could not be realized.
  • Comparative Example 2 the coefficient of variation CV (Na/Nb) was high and coarse particles of 10 ⁇ m or more were present, making it impossible to realize a thin film-like thermally conductive member.
  • Comparative Example 3 the D10 and span values were out of the specified range, the viscosity was so high that it could not be measured, and the thermal conductivity was also low.

Abstract

The present invention provides an alumina powder which comprises alumina particles having a circle-equivalent diameter of less than 0.3 µm, wherein: the particle diameter D10 at a cumulative percentage of 10% from the finest particle side in the number-based cumulative particle size distribution is less than 15 µm; the particle diameter D10, the particle diameter D100 at a cumulative percentage of 100% from the finest particle side in the number-based cumulative particle size distribution, and the particle diameter D50 at a cumulative percentage of 50% from the finest particle side in the number-based cumulative particle size distribution satisfy formula (1) 4.0 ≤ (D100 - D10)/D50 ≤ 20; and if at least 5 fields of view are examined at a magnification of 10,000 times, the variation coefficient CV(Na/Nb) of the particle ratio (Na/Nb) of the number Na of alumina particles that have a circle-equivalent diameter of less than 0.3 µm to the number Nb of alumina particles that have a circle-equivalent diameter of not less than 0.3 µm is 0.3 or less.

Description

アルミナ粉末、樹脂組成物、およびアルミナ粉末の製造方法Alumina powder, resin composition, and method for producing alumina powder
　本開示は、アルミナ粉末、樹脂組成物、およびアルミナ粉末の製造方法に関する。 The present disclosure relates to alumina powder, a resin composition, and a method for producing alumina powder.
　電子部品に通電することにより発生する熱は、電子部品の性能に悪影響を及ぼしやすいことから速やかに放熱されることが望まれる。よって、放熱のための熱伝導性部材を構成する材料には、高い熱伝導性を示すことが望まれる。上記熱伝導性部材の一つとして、樹脂と無機粒子とを含む熱伝導性樹脂組成物があり、無機粒子としてアルミナ粒子が利用される。 The heat generated by energizing electronic components tends to have a negative effect on the performance of electronic components, so it is desirable that the heat be dissipated quickly. Therefore, the material constituting the thermally conductive member for heat radiation is desired to exhibit high thermal conductivity. As one of the above thermally conductive members, there is a thermally conductive resin composition containing a resin and inorganic particles, and alumina particles are used as the inorganic particles.
　上記アルミナ粒子として、例えば特許文献１に示された、バイヤー法による水酸化アルミニウムの焼成により得られるアルミナ粒子であって、ＢＥＴ比表面積が５～９ｍ２／ｇ、粒度分布におけるＤ１０＝０．１～０．２μｍ、Ｄ５０＝０．３～０．５μｍ、Ｄ９０＝０．７～２μｍで、かつ１μｍ以下が８０質量％以上であって、Ｍｇ含有量、Ｎａ含有量、Ｓｉ含有量、およびＣａ含有量を規定した易焼結性アルミナ粒子が挙げられる。 The above-mentioned alumina particles are, for example, alumina particles obtained by firing aluminum hydroxide according to the Bayer method, as shown in Patent Document 1, and have a BET specific surface area of 5 to 9 m 2 /g and D10 in particle size distribution of 0.1. ~0.2μm, D50=0.3~0.5μm, D90=0.7~2μm, and 80% by mass or more of 1μm or less, Mg content, Na content, Si content, and Ca Easily sinterable alumina particles with a specified content can be mentioned.
特開２００５－２０６４６０号公報Japanese Patent Application Publication No. 2005-206460
　近年、放熱のための熱伝導性部材として、膜厚の薄いシート状熱伝導性部材、例えば十数ミクロンレベル、更には数ミクロンレベルの膜厚の熱伝導性部材が求められている。更に熱伝導性部材には、より高い熱伝導性を示すことも求められている。また、高熱伝導性を実現するには、樹脂中にアルミナ粒子を高濃度かつ均一に分散させる必要がある。 In recent years, as a thermally conductive member for heat dissipation, there has been a demand for a sheet-like thermally conductive member with a thin film thickness, for example, a thermally conductive member with a film thickness on the order of tens of microns, or even on the level of several microns. Furthermore, thermally conductive members are also required to exhibit higher thermal conductivity. Furthermore, in order to achieve high thermal conductivity, it is necessary to uniformly disperse alumina particles in the resin at a high concentration.
　しかしながら、上記特許文献１に示されたアルミナ粒子を多量に樹脂に配合すると、アルミナ粒子が凝集しやすく、樹脂組成物中に粗粒が生じやすい。その結果、高熱伝導性を達成することが難しく、また熱伝導性部材の薄膜化も難しい。 However, when a large amount of alumina particles shown in Patent Document 1 are blended into a resin, the alumina particles tend to aggregate, and coarse particles tend to occur in the resin composition. As a result, it is difficult to achieve high thermal conductivity, and it is also difficult to make the thermally conductive member thin.
　本開示は、上記事情に鑑みてなされたものであって、その目的は、熱伝導性が高く、かつ薄膜状の熱伝導性部材を実現できるアルミナ粉末と、該アルミナ粉末を含み、熱伝導性が高く、かつ薄膜状の熱伝導性部材を実現できる樹脂組成物と、前記アルミナ粉末の製造方法を提供することにある。 The present disclosure has been made in view of the above circumstances, and aims to provide an alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a thermally conductive material containing the alumina powder. It is an object of the present invention to provide a resin composition that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a method for producing the alumina powder.
　本発明の態様１は、
　円相当径が０．３μｍ未満のアルミナ粒子を有するアルミナ粉末であって、
　個数基準の累積粒度分布の微粒側から累積１０％の粒径Ｄ１０が０．１５μｍ未満であり、
　前記Ｄ１０と、個数基準の累積粒度分布の微粒側から累積１００％の粒径Ｄ１００と、個数基準の累積粒度分布の微粒側から累積５０％の粒径Ｄ５０とが、下記式（１）を満たし、
　倍率１０，０００倍で少なくとも５視野観察したときに、円相当径が０．３μｍ未満のアルミナ粒子数Ｎａと円相当径が０．３μｍ以上のアルミナ粒子数Ｎｂの粒子比率（Ｎａ／Ｎｂ）の変動係数であるＣＶ（Ｎａ／Ｎｂ）が０．３以下である、アルミナ粉末である。
　４．０≦（Ｄ１００－Ｄ１０）／Ｄ５０≦２０　・・・（１） Aspect 1 of the present invention is
An alumina powder having alumina particles having an equivalent circle diameter of less than 0.3 μm,
The cumulative particle size D10 of 10% from the fine particle side of the number-based cumulative particle size distribution is less than 0.15 μm,
The above D10, the cumulative particle size D100 of 100% from the fine particle side of the number-based cumulative particle size distribution, and the cumulative particle size D50 of 50% from the fine particle side of the number-based cumulative particle size distribution satisfy the following formula (1). ,
When observing at least 5 fields of view at a magnification of 10,000 times, the particle ratio (Na/Nb) of the number of alumina particles Na with an equivalent circle diameter of less than 0.3 μm and the number Nb of alumina particles with an equivalent circle diameter of 0.3 μm or more was determined. The alumina powder has a coefficient of variation (CV (Na/Nb)) of 0.3 or less.
4.0≦(D100-D10)/D50≦20...(1)
　本発明の態様２は、
　前記円相当径が０．３μｍ未満のアルミナ粒子は、平均円形度が０．８２以上である、態様１に記載のアルミナ粉末である。 Aspect 2 of the present invention is
The alumina particles having an equivalent circle diameter of less than 0.3 μm are the alumina powder according to aspect 1, wherein the average circularity is 0.82 or more.
　本発明の態様３は、
　前記円相当径が０．３μｍ未満のアルミナ粒子は、αアルミナ粒子である、態様１または２に記載のアルミナ粉末である。 Aspect 3 of the present invention is
The alumina particles having an equivalent circle diameter of less than 0.3 μm are the alumina powder according to aspect 1 or 2, wherein the alumina particles are α-alumina particles.
　本発明の態様４は、
　態様１～３のいずれかに記載のアルミナ粉末と樹脂を含む、樹脂組成物である。 Aspect 4 of the present invention is
A resin composition comprising the alumina powder according to any one of aspects 1 to 3 and a resin.
　本発明の態様５は、
　前記アルミナ粉末と樹脂の質量割合が８５：１５～９５：５の範囲である態様４に記載の樹脂組成物である。 Aspect 5 of the present invention is
The resin composition according to aspect 4, wherein the mass ratio of the alumina powder to the resin is in the range of 85:15 to 95:5.
　本発明の態様６は、
　円相当径が０．３μｍ未満のアルミナ原料粒子と、円相当径が０．３μｍ以上のアルミナ原料粒子を含む配合原料を準備する原料準備工程と、
　前記配合原料を、回転速度が１００００ｒｐｍ以上である高速ミキサーを用いて混合する混合工程とを有する、アルミナ粉末の製造方法である。 Aspect 6 of the present invention is
a raw material preparation step of preparing a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 μm and alumina raw material particles with an equivalent circle diameter of 0.3 μm or more;
The method for producing alumina powder includes a mixing step of mixing the blended raw materials using a high-speed mixer with a rotation speed of 10,000 rpm or more.
　本開示によれば、熱伝導性が高く、薄膜状の熱伝導性部材を実現できるアルミナ粉末と、該アルミナ粉末を含み、熱伝導性が高く、薄膜状の熱伝導性部材を実現できる樹脂組成物と、前記アルミナ粉末の製造方法を提供できる。 According to the present disclosure, an alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a resin composition that includes the alumina powder and has high thermal conductivity and can realize a thin film-like thermally conductive member. and a method for producing the alumina powder.
図１は、実施例で使用したアルミナ原料粒子２のＳＥＭ写真である。FIG. 1 is a SEM photograph of alumina raw material particles 2 used in Examples. 図２は、実施例で使用したアルミナ原料粒子５のＳＥＭ写真である。FIG. 2 is a SEM photograph of the alumina raw material particles 5 used in the examples. 図３は、実施例で使用したアルミナ原料粒子２とアルミナ原料粒子５の、レーザー回折・散乱式粒子径分布測定装置で測定した体積基準の粒度分布を示す図である。FIG. 3 is a diagram showing the volume-based particle size distribution of alumina raw material particles 2 and alumina raw material particles 5 used in Examples, as measured by a laser diffraction/scattering type particle size distribution measuring device. 図４は、実施例で行った二値化処理の一例を示す図である。FIG. 4 is a diagram showing an example of the binarization process performed in the example. 図５は、実施例１の断面サンプルのＳＥＭ画像である。FIG. 5 is a SEM image of the cross-sectional sample of Example 1. 図６は、実施例１の断面サンプルの別のＳＥＭ画像である。FIG. 6 is another SEM image of the cross-sectional sample of Example 1. 図７は、比較例１の断面サンプルのＳＥＭ画像である。FIG. 7 is a SEM image of a cross-sectional sample of Comparative Example 1. 図８は、比較例１の断面サンプルの別のＳＥＭ画像である。FIG. 8 is another SEM image of the cross-sectional sample of Comparative Example 1. 図９は、比較例３の断面サンプルのＳＥＭ画像である。FIG. 9 is a SEM image of a cross-sectional sample of Comparative Example 3.
　本発明者らは、熱伝導性が高く、薄膜状の熱伝導性部材を実現できるアルミナ粉末と、該アルミナ粉末を含み、熱伝導性が高く、薄膜状の熱伝導性部材を実現できる樹脂組成物、更には上記アルミナ粉末の製造方法を実現すべく、鋭意研究を重ねた。その結果、上記アルミナ粉末として、円相当径が０．３μｍ未満のアルミナ粒子を有し、個数基準の累積粒度分布の微粒側から、累積１０％の粒径をＤ１０、累積５０％の粒径をＤ５０、累積１００％の粒径をＤ１００としたときに、Ｄ１０の範囲を規定するとともに、Ｄ１０、Ｄ５０およびＤ１００が所定の式を満たし、更に所定の条件で観察したときに、アルミナ粒子の分散状態を示すパラメータである、円相当径が０．３μｍ未満のアルミナ粒子数Ｎａと円相当径が０．３μｍ以上のアルミナ粒子数Ｎｂの粒子比率（Ｎａ／Ｎｂ）の変動係数であるＣＶ（Ｎａ／Ｎｂ）が、一定以下であればよいことを見出した。 The present inventors have developed an alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member, and a resin composition containing the alumina powder that has high thermal conductivity and can realize a thin film-like thermally conductive member. In order to realize the manufacturing method of the above-mentioned alumina powder, we conducted extensive research. As a result, the above alumina powder has alumina particles with an equivalent circle diameter of less than 0.3 μm, and from the fine particle side of the cumulative particle size distribution based on number, the cumulative particle size of 10% is D10, and the cumulative particle size of 50% is D10. D50, when the cumulative 100% particle size is D100, the range of D10 is defined, D10, D50 and D100 satisfy a predetermined formula, and when observed under predetermined conditions, the dispersion state of alumina particles CV (Na / It has been found that it is sufficient if Nb) is below a certain level.
　以下、本実施形態に係るアルミナ粉末、該アルミナ粉末を含む樹脂組成物、およびアルミナ粉末の製造方法について順に詳述する。 Hereinafter, the alumina powder, the resin composition containing the alumina powder, and the method for producing the alumina powder according to the present embodiment will be described in detail in order.
　〔アルミナ粉末〕
　（円相当径が０．３μｍ未満のアルミナ粒子を含有）
　本実施形態に係るアルミナ粉末は、円相当径が０．３μｍ未満のアルミナ粒子（以下「アルミナ小粒子」ということがある）を含有する。本実施形態に係るアルミナ粉末は、アルミナ小粒子を含み、かつ後述する規定の粒度分布を満たす範囲内で、円相当径が０．３μｍ以上のアルミナ粒子（以下「アルミナ大粒子」ということがある）も含みうる。アルミナ小粒子は、円相当径の下限が例えば０．０１μｍでありうる。またアルミナ大粒子は円相当径の上限が３μｍ以下でありうる。 [Alumina powder]
(Contains alumina particles with an equivalent circle diameter of less than 0.3 μm)
The alumina powder according to the present embodiment contains alumina particles having an equivalent circle diameter of less than 0.3 μm (hereinafter sometimes referred to as “small alumina particles”). The alumina powder according to this embodiment includes small alumina particles and has an equivalent circle diameter of 0.3 μm or more (hereinafter sometimes referred to as "large alumina particles") within a range that satisfies the specified particle size distribution described below. ) may also be included. The lower limit of the equivalent circle diameter of the alumina small particles may be, for example, 0.01 μm. Further, the upper limit of the equivalent circle diameter of the large alumina particles may be 3 μm or less.
　（個数基準の累積粒度分布の微粒側から累積１０％の粒径Ｄ１０）
　本実施形態に係るアルミナ粉末は、個数基準の累積粒度分布の微粒側から累積１０％の粒径Ｄ１０（以下単に「Ｄ１０」と記載することがある）が０．１５μｍ未満である。アルミナ粉末に、アルミナ小粒子として微粒である粒径が０．１５μｍ未満のアルミナ微粒子が含まれることによって、アルミナ大粒子間に形成される隙間に上記アルミナ微粒子が存在し、高充填を容易に実現でき、熱伝導性を高めることができる。また、比較的大きなアルミナ粒子の表面に、上記アルミナ微粒子が存在することによって、樹脂組成物を製造する際に、樹脂中でのアルミナ粉末の流動性も高められる。上記Ｄ１０は、好ましくは０．１０μｍ以下である。なお、樹脂組成物混合時の流動性の観点から、上記Ｄ１０の下限値は０．０１μｍ程度でありうる。 (Particle size D10 of cumulative 10% from the fine particle side of cumulative particle size distribution based on number)
The alumina powder according to the present embodiment has a cumulative particle size D10 (hereinafter sometimes simply referred to as "D10") of 10% from the fine particle side of the number-based cumulative particle size distribution of less than 0.15 μm. Since the alumina powder contains fine alumina particles with a particle size of less than 0.15 μm, the alumina fine particles exist in the gaps formed between large alumina particles, making it easy to achieve high filling. It is possible to improve thermal conductivity. Moreover, the presence of the fine alumina particles on the surface of relatively large alumina particles also improves the fluidity of the alumina powder in the resin when producing a resin composition. The above D10 is preferably 0.10 μm or less. In addition, from the viewpoint of fluidity during mixing of the resin composition, the lower limit of the above D10 may be about 0.01 μm.
　（スパン値：（Ｄ１００－Ｄ１０）／Ｄ５０）
　本実施形態に係るアルミナ粉末は、前記Ｄ１０と、個数基準の累積粒度分布の微粒側から累積１００％の粒径Ｄ１００と、個数基準の累積粒度分布の微粒側から累積５０％の粒径Ｄ５０とが、下記式（１）を満たす。以下では、下記式（１）における（Ｄ１００－Ｄ１０）／Ｄ５０を「スパン値」ということがある。
　４．０≦（Ｄ１００－Ｄ１０）／Ｄ５０≦２０　・・・（１） (Span value: (D100-D10)/D50)
The alumina powder according to the present embodiment has the above-mentioned D10, a cumulative particle size D100 of 100% from the fine grain side of the number-based cumulative particle size distribution, and a cumulative particle size D50 of 50% from the fine grain side of the number-based cumulative particle size distribution. satisfies the following formula (1). Hereinafter, (D100-D10)/D50 in the following formula (1) may be referred to as a "span value."
4.0≦(D100-D10)/D50≦20...(1)
　上記スパン値は、粒度分布の広がりを示す指標である。上記スパン値が４．０を下回ると、アルミナ小粒子の粒径とアルミナ大粒子の粒径との差が小さくなる。その結果、アルミナ小粒子の粒径が、アルミナ大粒子の粒径に近い場合には、上述した比較的大きなアルミナ粒子間に形成される隙間へのアルミナ微粒子の充填が難しくなる。一方、アルミナ大粒子の粒径が、アルミナ小粒子の粒径に近い場合には、アルミナ粉末の大部分が粒径の比較的小さい粒子で占められ、結果として、優れた熱伝導性と良好な流動性を確保することが困難となる。上記スパン値は、好ましくは４．１以上、より好ましくは４．３以上、更に好ましくは５．３以上である。 The above span value is an index indicating the spread of the particle size distribution. When the span value is less than 4.0, the difference between the particle diameters of the small alumina particles and the large alumina particles becomes small. As a result, if the particle size of the small alumina particles is close to the particle size of the large alumina particles, it becomes difficult to fill the gaps formed between the relatively large alumina particles with the alumina fine particles. On the other hand, when the particle size of the large alumina particles is close to the particle size of the small alumina particles, most of the alumina powder is occupied by particles with relatively small particle sizes, resulting in excellent thermal conductivity and good properties. It becomes difficult to secure liquidity. The span value is preferably 4.1 or more, more preferably 4.3 or more, even more preferably 5.3 or more.
　一方、上記スパン値が２０を超えると、比較的大きなアルミナ粒子の粒径（Ｄ５０）が５μｍ以上となることが想定される。この場合、アルミナ大粒子の粒度分布を考慮すると、膜厚の薄い薄膜状の熱伝導性部材の実現が難しくなり、例えば膜厚が１０μｍ以下の薄膜状の熱伝導性部材の実現できない。上記スパン値は、好ましくは１５以下、より好ましくは１２以下、更に好ましくは６．３以下、最も好ましくは６．０以下である。 On the other hand, when the span value exceeds 20, it is assumed that the particle size (D50) of the relatively large alumina particles will be 5 μm or more. In this case, considering the particle size distribution of large alumina particles, it becomes difficult to realize a thin film-like thermally conductive member with a thin film thickness, for example, a thin film-like thermally conductive member with a film thickness of 10 μm or less cannot be realized. The span value is preferably 15 or less, more preferably 12 or less, still more preferably 6.3 or less, and most preferably 6.0 or less.
　（円相当径が０．３μｍ未満のアルミナ粒子数Ｎａと、円相当径が０．３μｍ以上のアルミナ粒子数Ｎｂとの粒子比率（Ｎａ／Ｎｂ）の変動係数であるＣＶ（Ｎａ／Ｎｂ））
　本実施形態に係るアルミナ粉末は、倍率１０，０００倍で少なくとも５視野観察したときに、円相当径が０．３μｍ未満のアルミナ粒子数Ｎａと、円相当径が０．３μｍ以上のアルミナ粒子数Ｎｂとの粒子比率（Ｎａ／Ｎｂ）の変動係数であるＣＶ（Ｎａ／Ｎｂ）が０．３以下を満たす。 (CV (Na/Nb), which is the coefficient of variation of the particle ratio (Na/Nb) between the number of alumina particles Na with an equivalent circle diameter of less than 0.3 μm and the number Nb of alumina particles with an equivalent circle diameter of 0.3 μm or more)
When the alumina powder according to the present embodiment is observed at least 5 fields of view at a magnification of 10,000 times, the number Na of alumina particles having an equivalent circle diameter of less than 0.3 μm, and the number Na of alumina particles having an equivalent circle diameter of 0.3 μm or more. CV (Na/Nb), which is the coefficient of variation of the particle ratio with Nb (Na/Nb), satisfies 0.3 or less.
　本実施形態に係るアルミナ粉末は、多量のアルミナ粉末を樹脂と混合および混練した場合でも、アルミナ粉末の分散性が高く凝集粒の発生が抑制された樹脂組成物が得られる。その結果、熱伝導性が高くなり、薄膜状の熱伝導性部材を実現できる。本実施形態に係るアルミナ粉末が、従来品と異なり、樹脂組成物において良好に分散することを示すため、本実施形態では、アルミナ粉末の分散性の評価指標として、円相当径が０．３μｍ未満のアルミナ粒子数Ｎａと、円相当径が０．３μｍ以上のアルミナ粒子数Ｎｂとの粒子比率（Ｎａ／Ｎｂ）の変動係数であるＣＶ（Ｎａ／Ｎｂ）を用いる。 Even when a large amount of alumina powder is mixed and kneaded with a resin, the alumina powder according to the present embodiment provides a resin composition in which the alumina powder has high dispersibility and the generation of agglomerated particles is suppressed. As a result, the thermal conductivity becomes high, and a thin film-like thermally conductive member can be realized. In order to show that the alumina powder according to this embodiment is well dispersed in a resin composition, unlike conventional products, in this embodiment, the equivalent circle diameter is less than 0.3 μm as an evaluation index of the dispersibility of alumina powder. CV (Na/Nb) is used, which is the coefficient of variation of the particle ratio (Na/Nb) between the number Na of alumina particles having a circular equivalent diameter of 0.3 μm or more and the number Nb of alumina particles having an equivalent circle diameter of 0.3 μm or more.
　また、上記変動係数ＣＶ（Ｎａ／Ｎｂ）は、倍率１０，０００倍で少なくとも５視野観察して求められる。変動係数ＣＶ（Ｎａ／Ｎｂ）の評価は、走査型電子顕微鏡を用いて行えばよい。 Further, the coefficient of variation CV (Na/Nb) is determined by observing at least 5 visual fields at a magnification of 10,000 times. The coefficient of variation CV (Na/Nb) may be evaluated using a scanning electron microscope.
　上記変動係数ＣＶ（Ｎａ／Ｎｂ）を満たすアルミナ粉末を得るための方法として、従来の方法でアルミナ原料粒子を混合するのではなく、後述するアルミナ粉末の製造方法に示す通り、回転速度が１００００ｒｐｍ以上である高速ミキサーを用いて混合することが重要である。 As a method for obtaining alumina powder that satisfies the above coefficient of variation CV (Na/Nb), instead of mixing alumina raw material particles using the conventional method, as shown in the method for producing alumina powder described below, the rotation speed is 10,000 rpm or more. It is important to mix using a high speed mixer.
　前記変動係数ＣＶ（Ｎａ／Ｎｂ）は、好ましくは０．２５以下であり、より好ましくは０．２０以下である。前記変動係数ＣＶ（Ｎａ／Ｎｂ）は、小さければ小さいほど好ましい。 The coefficient of variation CV (Na/Nb) is preferably 0.25 or less, more preferably 0.20 or less. The smaller the coefficient of variation CV (Na/Nb) is, the more preferable it is.
　（円相当径が０．３μｍ未満のアルミナ粒子の平均円形度）
　本実施形態に係るアルミナ粉末は、円相当径が０．３μｍ未満のアルミナ粒子の平均円形度が０．８２以上であることが好ましい。好ましくはアルミナ小粒子の円形度が高いことによって、樹脂と混合および混練時に、流動性をより高めることができる。アルミナ小粒子の平均円形度は、より好ましくは０．８５以上であり、アルミナ小粒子の平均円形度は高いほど好ましいが、０．９５以下であれば同等の流動性を確保できる。 (Average circularity of alumina particles with equivalent circle diameter of less than 0.3 μm)
In the alumina powder according to the present embodiment, it is preferable that the average circularity of the alumina particles having an equivalent circle diameter of less than 0.3 μm is 0.82 or more. Preferably, the alumina small particles have a high degree of circularity, so that the fluidity can be further improved when mixed and kneaded with the resin. The average circularity of the alumina small particles is more preferably 0.85 or more, and the higher the average circularity of the alumina small particles is, the more preferable it is, but if it is 0.95 or less, equivalent fluidity can be ensured.
　（円相当径が０．３μｍ未満のアルミナ粒子の結晶構造）
　本実施形態に係るアルミナ粉末は、円相当径が０．３μｍ未満のアルミナ粒子がαアルミナ粒子であることが好ましい。なお、αアルミナ粒子であることは、例えば、アルミナ粉末を粉末Ｘ線回折法により測定し、得られた回折スペクトルから、２θ＝２５．６°の位置に現れるα相（０１２面）のピーク高さと、２θ＝４６°の位置に現れるγ相等の他の相のピーク高さを比較するか、または樹脂組成物を用いて評価する場合、収束イオンビーム（ＦＩＢ）を使用して厚さ０．１μｍ程度の薄片をＦＩＢ作成し、円相当径が０．３μｍ未満の粒子について、電子線回折により確認することができる。 (Crystal structure of alumina particles with equivalent circle diameter of less than 0.3 μm)
In the alumina powder according to the present embodiment, the alumina particles having an equivalent circle diameter of less than 0.3 μm are preferably α-alumina particles. Note that α-alumina particles are determined by, for example, the peak height of the α-phase (012 plane) appearing at the position of 2θ = 25.6° from the diffraction spectrum obtained by measuring alumina powder by powder X-ray diffraction method. Compare the peak heights of other phases such as the γ phase that appear at the position of 2θ = 46°, or when evaluating using a resin composition, use a focused ion beam (FIB) to compare the peak heights of other phases such as the γ phase that appear at the position of 2θ = 46°. A thin section of about 1 μm is prepared by FIB, and particles with an equivalent circle diameter of less than 0.3 μm can be confirmed by electron beam diffraction.
　一方、円相当径が０．３μｍ以上のアルミナ粒子の結晶構造は限定されない。例えば、αアルミナ、θアルミナ、γアルミナ、δアルミナのうちの１以上であることが挙げられる。熱伝導性を高める観点からは、円相当径が０．３μｍ以上のアルミナ粒子もαアルミナ粒子であることが好ましい。 On the other hand, the crystal structure of alumina particles having an equivalent circle diameter of 0.3 μm or more is not limited. For example, it may be one or more of α alumina, θ alumina, γ alumina, and δ alumina. From the viewpoint of increasing thermal conductivity, it is preferable that the alumina particles having an equivalent circle diameter of 0.3 μm or more are also α-alumina particles.
　〔アルミナ粉末の製造方法〕
　本実施形態に係るアルミナ粉末の製造方法は、
　円相当径が０．３μｍ未満のアルミナ原料粒子と、円相当径が０．３μｍ以上のアルミナ原料粒子を含む配合原料を準備する原料準備工程と、
　前記配合原料を、回転速度が１００００ｒｐｍ以上である高速ミキサーを用いて混合する混合工程とを有する。 [Method for producing alumina powder]
The method for producing alumina powder according to this embodiment is as follows:
a raw material preparation step of preparing a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 μm and alumina raw material particles with an equivalent circle diameter of 0.3 μm or more;
and a mixing step of mixing the blended raw materials using a high-speed mixer with a rotation speed of 10,000 rpm or more.
　（原料準備工程）
　円相当径が０．３μｍ未満のアルミナ原料粒子と、円相当径が０．３μｍ以上のアルミナ原料粒子を含む配合原料を準備するが、これらのアルミナ原料粒子の製造方法は特に限定されない。例えば、市販品を用いることができる。または、従来知られている方法で製造することができる。 (Raw material preparation process)
A blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 μm and alumina raw material particles with an equivalent circle diameter of 0.3 μm or more is prepared, but the method for producing these alumina raw material particles is not particularly limited. For example, commercially available products can be used. Alternatively, it can be manufactured by a conventionally known method.
　円相当径が０．３μｍ未満のアルミナ原料粒子の平均円形度は０．８２以上であることが好ましい。円相当径が０．３μｍ未満のアルミナ原料粒子の平均円形度は、より好ましくは０．８５以上であり、高いほど好ましいが、０．９５以下であっても良い。円相当径が０．３μｍ以上のアルミナ原料粒子の平均円形度は特に限定されない。 It is preferable that the average circularity of the alumina raw material particles having an equivalent circle diameter of less than 0.3 μm is 0.82 or more. The average circularity of the alumina raw material particles having an equivalent circular diameter of less than 0.3 μm is more preferably 0.85 or more, and is preferably as high as possible, but may be 0.95 or less. The average circularity of the alumina raw material particles having an equivalent circle diameter of 0.3 μm or more is not particularly limited.
　前記円相当径が０．３μｍ未満のアルミナ原料粒子は、αアルミナ原料粒子であることが好ましい。円相当径が０．３μｍ以上のアルミナ原料粒子は、例えば、αアルミナ、θアルミナ、γアルミナ、δアルミナのうちの１以上で構成されるアルミナ原料粒子が挙げられる。熱伝導性の高いアルミナ粉末を得る観点からは、円相当径が０．３μｍ以上のアルミナ原料粒子もαアルミナ原料粒子であることが好ましい。 The alumina raw material particles having an equivalent circle diameter of less than 0.3 μm are preferably α-alumina raw material particles. Examples of the alumina raw material particles having an equivalent circle diameter of 0.3 μm or more include alumina raw material particles composed of one or more of α alumina, θ alumina, γ alumina, and δ alumina. From the viewpoint of obtaining alumina powder with high thermal conductivity, it is preferable that the alumina raw material particles having an equivalent circle diameter of 0.3 μm or more are also α alumina raw material particles.
　Ｄ１０およびスパン値が上述した範囲内にある本実施形態のアルミナ粉末を得るには、円相当径が０．３μｍ未満のアルミナ原料粒子と、円相当径が０．３μｍ以上のアルミナ原料粒子の配合割合（質量割合）を、例えば４０：６０～１０：９０とすることが好ましい。 In order to obtain the alumina powder of this embodiment whose D10 and span values are within the ranges described above, alumina raw material particles with an equivalent circle diameter of less than 0.3 μm and alumina raw material particles with an equivalent circle diameter of 0.3 μm or more are mixed. The ratio (mass ratio) is preferably 40:60 to 10:90, for example.
　前記配合原料には、混合時の流動性等の向上を目的として、シランカップリング剤、分散剤等を含んでいてもよい。 The blended raw materials may contain a silane coupling agent, a dispersant, etc. for the purpose of improving fluidity during mixing.
　（混合工程）
　変動係数ＣＶ（Ｎａ／Ｎｂ）が上記範囲を満たすアルミナ粉末を得るには、円相当径が０．３μｍ未満のアルミナ原料粒子と、円相当径が０．３μｍ以上のアルミナ原料粒子を含む配合原料を準備するだけでなく、これらのアルミナ原料粒子の混合方法が重要である。本実施形態に係るアルミナ粉末の製造方法では、上記粒径の異なる粒子を混合する手段として、回転速度が１００００ｒｐｍ以上である高速ミキサーを用いることにより、凝集体の形成が十分抑制され、変動係数ＣＶ（Ｎａ／Ｎｂ）が上記範囲を満たすアルミナ粉末を得ることができる。その結果、該アルミナ粉末を樹脂と混合し混練することで、アルミナ粉末の凝集部分の形成が十分抑制され、高充填でありながら分散性良くアルミナ粉末を含む樹脂組成物を得ることができる。 (Mixing process)
In order to obtain an alumina powder whose variation coefficient CV (Na/Nb) satisfies the above range, a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 μm and alumina raw material particles with an equivalent circle diameter of 0.3 μm or more is required. In addition to the preparation, the method of mixing these alumina raw material particles is important. In the method for producing alumina powder according to the present embodiment, by using a high-speed mixer with a rotation speed of 10,000 rpm or more as a means for mixing the particles having different particle sizes, the formation of aggregates is sufficiently suppressed, and the coefficient of variation CV It is possible to obtain alumina powder in which (Na/Nb) satisfies the above range. As a result, by mixing and kneading the alumina powder with a resin, the formation of agglomerated portions of the alumina powder is sufficiently suppressed, and it is possible to obtain a highly filled resin composition containing alumina powder with good dispersibility.
　前記回転速度が１００００ｒｐｍ以上である高速ミキサーとは、１００００ｒｐｍ以上の高速回転で粉体を混合する装置であり、例えばバッチ式ミルやロータースピードミルが挙げられる。従来、粉末の混合に使用されてきた、一般的な混合装置、例えばエアーブレンダー、ロッキングブレンダー、ヘンシェルミキサー（いずれも回転速度は４７０～５４００ｒｐｍ）、遊星撹拌混合装置（回転速度は２０００ｒｐｍ以下）では、円相当径が０．３μｍ未満のアルミナ小粒子の凝集粒を解砕することが困難であり、樹脂組成物を作製した際に凝集粒が存在する。その結果、薄膜状の樹脂組成物、例えば膜厚が５μｍ以下のごく薄い樹脂組成物の作製は難しい。また、高速ミキサーを用いることで、円相当径が０．３μｍ未満のアルミナ小粒子の凝集粒を解砕し、円相当径が０．３μｍ以上のアルミナ原料粒子の一次粒子表面に分散できる。また、円相当径が０．３μｍ以上のアルミナ原料粒子の再凝集を防ぎ、その結果、変動係数ＣＶ（Ｎａ／Ｎｂ）が上記範囲を満たすアルミナ粉末が得られる。 The high-speed mixer whose rotational speed is 10,000 rpm or more is a device that mixes powder at a high-speed rotation of 10,000 rpm or more, and includes, for example, a batch type mill and a rotor speed mill. Conventionally, common mixing devices used for mixing powders, such as air blenders, rocking blenders, Henschel mixers (all with rotation speeds of 470 to 5,400 rpm), and planetary stirring mixers (with rotation speeds of 2,000 rpm or less), It is difficult to disintegrate agglomerated particles of small alumina particles having an equivalent circular diameter of less than 0.3 μm, and agglomerated particles are present when a resin composition is produced. As a result, it is difficult to produce a resin composition in the form of a thin film, for example, a very thin resin composition with a film thickness of 5 μm or less. Furthermore, by using a high-speed mixer, agglomerated particles of small alumina particles with an equivalent circle diameter of less than 0.3 μm can be broken up and dispersed on the surface of primary particles of alumina raw material particles with an equivalent circle diameter of 0.3 μm or more. Furthermore, reagglomeration of alumina raw material particles having an equivalent circle diameter of 0.3 μm or more is prevented, and as a result, an alumina powder having a coefficient of variation CV (Na/Nb) satisfying the above range is obtained.
　〔樹脂組成物〕
　本実施形態に係る樹脂組成物は、本実施形態に係るアルミナ粉末と、樹脂とを含む。本実施形態に係るアルミナ粉末を、例えば熱伝導性樹脂組成物用フィラーとして使用することにより、熱伝導性の高い樹脂組成物（コンポジット）を得ることができる。 [Resin composition]
The resin composition according to this embodiment includes the alumina powder according to this embodiment and a resin. By using the alumina powder according to this embodiment, for example, as a filler for a thermally conductive resin composition, a resin composition (composite) with high thermal conductivity can be obtained.
　樹脂組成物の熱伝導性を確保するため、樹脂組成物に含まれる本実施形態に係るアルミナ粉末の割合（配合比率）は、４０体積％以上であることが好ましく、より好ましくは５０体積％以上である。一方、樹脂特有のしなやかさを確保する観点からは、前記アルミナ粉末の割合は、９０体積％以下であることが好ましく、より好ましくは８５体積％以下である。本実施形態に係る樹脂組成物は、好ましくは、アルミナ粉末が高充填されて、より高い熱伝導性を発揮しうる。アルミナ粉末が高充填された樹脂組成物の好ましい態様として、前記アルミナ粉末と樹脂の質量割合が８５：１５～９５：５の範囲であることが挙げられる。 In order to ensure the thermal conductivity of the resin composition, the proportion (blending ratio) of the alumina powder according to the present embodiment contained in the resin composition is preferably 40 volume% or more, more preferably 50 volume% or more. It is. On the other hand, from the viewpoint of ensuring the flexibility peculiar to the resin, the proportion of the alumina powder is preferably 90% by volume or less, more preferably 85% by volume or less. The resin composition according to the present embodiment is preferably highly filled with alumina powder and can exhibit higher thermal conductivity. A preferred embodiment of the resin composition highly filled with alumina powder is that the mass ratio of the alumina powder to the resin is in the range of 85:15 to 95:5.
　樹脂組成物に使用する樹脂としては、熱可塑性樹脂、熱可塑性エラストマー、熱硬化性樹脂の中から選択することができる。なお、樹脂は、１種単独で用いてもよいし、２種以上を併用してもよい。 The resin used in the resin composition can be selected from thermoplastic resins, thermoplastic elastomers, and thermosetting resins. In addition, one type of resin may be used alone, or two or more types may be used in combination.
　熱可塑性樹脂としては、ポリエチレン、ポリプロピレン、エチレン－プロピレン共重合体等のポリオレフィン系樹脂、ポリメチルペンテン、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリ酢酸ビニル、エチレン－酢酸ビニル共重合体、ポリビニルアルコール、ポリビニルアセタール、ポリフッ化ビニリデン及びポリテトラフルオロエチレン等のフッ素系重合体、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート、ポリスチレン、ポリアクリロニトリル、スチレン－アクリロニトリル共重合体、アクリロニトリル－ブタジエン－スチレン共重合体（ＡＢＳ）樹脂、ポリフェニレン－エーテル共重合体（ＰＰＥ）樹脂、変性ＰＰＥ樹脂、脂肪族ポリアミド類、芳香族ポリアミド類、ポリイミド、ポリアミドイミド、ポリメタクリル酸、ポリメタクリル酸メチルエステル等のポリメタクリル酸エステル類、ポリアクリル酸類、ポリカーボネート、ポリフェニレンスルフィド、ポリサルホン、ポリエーテルサルホン、ポリエーテルニトリル、ポリエーテルケトン、ポリケトン、液晶ポリマー、シリコーン樹脂、アイオノマー等が挙げられる。 Thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinyl Acetal, fluorine-based polymers such as polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer (ABS) ) resins, polyphenylene-ether copolymer (PPE) resins, modified PPE resins, aliphatic polyamides, aromatic polyamides, polyimides, polyamide-imides, polymethacrylic acid, polymethacrylic acid esters such as polymethacrylic acid methyl ester, Examples include polyacrylic acids, polycarbonates, polyphenylene sulfides, polysulfones, polyethersulfones, polyethernitrile, polyetherketones, polyketones, liquid crystal polymers, silicone resins, ionomers, and the like.
　熱可塑性エラストマーとしては、スチレン－ブタジエンブロック共重合体又はその水添化物、スチレン－イソプレンブロック共重合体又はその水添化物、スチレン系熱可塑性エラストマー、オレフィン系熱可塑性エラストマー、塩化ビニル系熱可塑性エラストマー、ポリエステル系熱可塑性エラストマー、ポリウレタン系熱可塑性エラストマー、ポリアミド系熱可塑性エラストマー等が挙げられる。 Examples of thermoplastic elastomers include styrene-butadiene block copolymers or hydrogenated products thereof, styrene-isoprene block copolymers or hydrogenated products thereof, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and vinyl chloride-based thermoplastic elastomers. , polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, and the like.
　熱硬化性樹脂としては、架橋ゴム、エポキシ樹脂、フェノール樹脂、ポリイミド樹脂、不飽和ポリエステル樹脂、ジアリルフタレート樹脂等が挙げられる。架橋ゴムの具体例としては、天然ゴム、アクリルゴム、ブタジエンゴム、イソプレンゴム、スチレン－ブタジエン共重合ゴム、ニトリルゴム、水添ニトリルゴム、クロロプレンゴム、エチレン－プロピレン共重合ゴム、塩素化ポリエチレンゴム、クロロスルホン化ポリエチレンゴム、ブチルゴム、ハロゲン化ブチルゴム、フッ素ゴム、ウレタンゴム、及びシリコーンゴムが挙げられる。 Examples of the thermosetting resin include crosslinked rubber, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, and the like. Specific examples of crosslinked rubber include natural rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene rubber, Examples include chlorosulfonated polyethylene rubber, butyl rubber, halogenated butyl rubber, fluororubber, urethane rubber, and silicone rubber.
　加工性や特性の観点から、ポリオレフィン系樹脂、アクリル系樹脂、ポリイミド系樹脂、ポリアミド系樹脂、ポリアミドイミド系樹脂、エポキシ系樹脂、フェノール系樹脂、シリコーン樹脂が好ましく用いられる。 From the viewpoint of processability and properties, polyolefin resins, acrylic resins, polyimide resins, polyamide resins, polyamideimide resins, epoxy resins, phenol resins, and silicone resins are preferably used.
　さらに、これらの樹脂組成物には、必要に応じて、発明の効果を損なわない範囲で可塑剤、硬化促進剤、カップリング剤、充填剤、顔料、難燃剤、酸化防止剤、界面活性剤、相溶化剤、耐候剤、抗ブロッキング剤、帯電防止剤、レベリング剤、離型剤などの公知の添加剤を単独または二種以上を適宜配合しても良い。 Furthermore, these resin compositions may contain plasticizers, curing accelerators, coupling agents, fillers, pigments, flame retardants, antioxidants, surfactants, Known additives such as a compatibilizer, a weathering agent, an anti-blocking agent, an antistatic agent, a leveling agent, and a mold release agent may be used alone or in combination of two or more.
　樹脂組成物の製造方法について説明する。本実施形態に係るアルミナ粉末と樹脂を混合することにより樹脂組成物を得ることができる。例えば、樹脂が液状の場合（例えば液状エポキシ樹脂など）は、液状樹脂とアルミナ粉末と硬化剤とを混合した後、熱または紫外線などで硬化させることにより樹脂組成物を得ることができる。硬化剤や混合方法、硬化方法は公知のものおよび方法を用いることができる。一方、樹脂が固体状の場合（例えばポリオレフィン樹脂やアクリル樹脂など）は、アルミナ粉末と樹脂を混合した後に、溶融混練などの公知の方法により混練することで、目的とする樹脂組成物を得ることができる。 The method for producing the resin composition will be explained. A resin composition can be obtained by mixing the alumina powder and resin according to this embodiment. For example, when the resin is liquid (e.g., liquid epoxy resin), the resin composition can be obtained by mixing the liquid resin, alumina powder, and a curing agent, and then curing with heat or ultraviolet rays. As the curing agent, mixing method, and curing method, known ones and methods can be used. On the other hand, if the resin is solid (for example, polyolefin resin or acrylic resin), the desired resin composition can be obtained by mixing the alumina powder and resin and then kneading them using a known method such as melt kneading. I can do it.
　本実施形態に係る樹脂組成物の態様には、アルミナ粉末と樹脂を含む原料を配合した配合物、アルミナ粉末と樹脂を含む原料を混合した混合物、該混合物を成形した成形物、混合物または成形物を例えば硬化処理して得られる成型体（硬化物）が含まれる。 Aspects of the resin composition according to the present embodiment include a mixture of alumina powder and a resin-containing raw material, a mixture of alumina powder and a resin-containing raw material, a molded product formed from the mixture, a mixture, or a molded product. It includes a molded body (cured product) obtained by, for example, curing treatment.
　本実施形態に係る樹脂組成物の一形態として、薄膜状の樹脂組成物が挙げられ、更にその一例として、膜厚が例えば１０μｍ以下、更には５μｍ以下の、薄膜状の樹脂組成物が挙げられる。 One form of the resin composition according to the present embodiment is a thin film resin composition, and another example thereof is a thin film resin composition with a film thickness of, for example, 10 μm or less, and further 5 μm or less. .
　以下、実施例を挙げて本発明の実施形態をより具体的に説明する。本開示は以下の実施例によって制限を受けるものではなく、前述および後述する趣旨に合致し得る範囲で、適宜変更を加えて実施することも可能であり、それらはいずれも本開示の技術的範囲に包含される。 Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples. The present disclosure is not limited by the following examples, and can be implemented with appropriate changes within the scope that can meet the spirit described above and below, and all of these are within the technical scope of the present disclosure. included in.
　〔アルミナ原料粒子の準備〕
　アルミナ原料粒子として、下記に記載のアルミナ原料粒子１～５を準備した。なお、各原料粒子の結晶相は、Ｘ線回折法により結晶構造を解析して求めた。本明細書において「粒径」は、レーザー回折・散乱式粒子径分布測定装置（マイクロトラックMT３３００ＥＸＩＩ、マイクロトラックベル社製）で測定した体積基準のメジアン径であり、前述のＤ５０とは区別される。
　（アルミナ原料粒子１）商品名：ＡＡ－０７（住友化学株式会社製）、粒径：０．９μｍ、結晶相：αアルミナ
　（アルミナ原料粒子２）開発品１（住友化学株式会社製）、粒径：０．１５μｍ、結晶相：αアルミナ
　（アルミナ原料粒子３）開発品２（住友化学株式会社製）、粒径：０．１０μｍ、結晶相：αアルミナ
　（アルミナ原料粒子４）商品名：ＡＳＦＰ－２０（デンカ株式会社製）、粒径：０．３μｍ、結晶相：θアルミナとδアルミナ
　（アルミナ原料粒子５）商品名：ＡＫＰ－５３（住友化学株式会社製）、粒径：０．１７μｍ、結晶相：αアルミナ [Preparation of alumina raw material particles]
Alumina raw material particles 1 to 5 described below were prepared as alumina raw material particles. The crystal phase of each raw material particle was determined by analyzing the crystal structure using an X-ray diffraction method. In this specification, "particle size" is a volume-based median diameter measured with a laser diffraction/scattering particle size distribution measuring device (Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.), and is distinguished from the above-mentioned D50. .
(Alumina raw material particles 1) Product name: AA-07 (manufactured by Sumitomo Chemical Co., Ltd.), particle size: 0.9 μm, crystal phase: α alumina (Alumina raw material particles 2) Development product 1 (manufactured by Sumitomo Chemical Co., Ltd.), grains Diameter: 0.15 μm, crystal phase: α alumina (alumina raw material particles 3) developed product 2 (manufactured by Sumitomo Chemical Co., Ltd.), particle size: 0.10 μm, crystal phase: α alumina (alumina raw material particles 4) product name: ASFP -20 (manufactured by Denka Co., Ltd.), particle size: 0.3 μm, crystal phase: θ alumina and δ alumina (alumina raw material particles 5) product name: AKP-53 (manufactured by Sumitomo Chemical Co., Ltd.), particle size: 0.17 μm , Crystal phase: α alumina
　なお、前記アルミナ原料粒子２（開発品１）は次の様にして製造した。まず種晶（αアルミナ）スラリーの調製を行った。具体的に、アルミナ粒子（種晶の原料）を水に分散させた後、ボールミルで湿式粉砕を行って湿式粉砕物を得た。その後、該湿式粉砕物を、回転数４０００ｒｐｍ、３０分間の条件で遠心処理し、沈殿物を除去して種晶が分散した種晶スラリーを得た。次いで、前記種晶スラリーとアルミニウムイソプロポキシドを高速で混合して加水分解し、水酸化アルミニウムスラリーを得た。得られた水酸化アルミニウムスラリーを１５０℃で乾燥し、水酸化アルミニウム粒子を得た。次いで、水酸化アルミニウム粒子を９６５℃にてガス炉で焼成し、アルミナ原料粒子２を得た。また、前記アルミナ原料粒子３（開発品２）は、前記アルミナ原料粒子２（開発品１）の製造方法において、上記アルミニウムイソプロポキシドと種晶スラリーとの配合比を変更することで得た。 Note that the alumina raw material particles 2 (developed product 1) were manufactured as follows. First, a seed crystal (α alumina) slurry was prepared. Specifically, alumina particles (raw material for seed crystals) were dispersed in water, and then wet-pulverized using a ball mill to obtain a wet-pulverized product. Thereafter, the wet pulverized product was centrifuged at a rotation speed of 4000 rpm for 30 minutes to remove precipitates to obtain a seed crystal slurry in which seed crystals were dispersed. Next, the seed crystal slurry and aluminum isopropoxide were mixed at high speed and hydrolyzed to obtain an aluminum hydroxide slurry. The obtained aluminum hydroxide slurry was dried at 150°C to obtain aluminum hydroxide particles. Next, the aluminum hydroxide particles were fired in a gas furnace at 965° C. to obtain alumina raw material particles 2. Further, the alumina raw material particles 3 (developed product 2) were obtained by changing the blending ratio of the aluminum isopropoxide and the seed crystal slurry in the manufacturing method of the alumina raw material particles 2 (developed product 1).
　本実施例で使用したアルミナ原料粒子２とアルミナ原料粒子５のＳＥＭ写真を図１と図２にそれぞれ示す。また、レーザー回折・散乱式粒子径分布測定装置（マイクロトラックMT３３００ＥＸＩＩ、マイクロトラックベル社製）で測定した、これらの原料粒子の体積基準の粒度分布を図３に示す。 SEM photographs of alumina raw material particles 2 and alumina raw material particles 5 used in this example are shown in FIGS. 1 and 2, respectively. Further, the volume-based particle size distribution of these raw material particles is shown in FIG. 3, as measured by a laser diffraction/scattering particle size distribution measuring device (Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.).
　〔アルミナ粉末の準備〕
　アルミナ原料粒子１～５とシランカップリング剤（商品名：ＯＦＳ－６０４０）を用い、表１に示す通り、実施例１～３、比較例１～３でそれぞれの配合量となるように配合して配合原料を得た。そして、表１に示す通り、該配合原料を、高速ミキサー混合または遊星撹拌混合してアルミナ粉末を得た。高速ミキサー混合では、バッチ式ミル（ＩＫＡ社製Ａ１０、回転数２００００ｒｐｍ）を用いて３０秒間混合し、アルミナ粉末として混合粉末を得た。また、遊星撹拌混合では、自転・公転ミキサー（ＡＲＶ－３１０、回転数２０００ｒｐｍ）を用いて３０秒間混合し、アルミナ粉末として混合粉末を得た。 [Preparation of alumina powder]
Using alumina raw material particles 1 to 5 and a silane coupling agent (trade name: OFS-6040), the amounts were blended in Examples 1 to 3 and Comparative Examples 1 to 3, as shown in Table 1. A blended raw material was obtained. Then, as shown in Table 1, the raw materials were mixed with a high speed mixer or mixed with planetary stirring to obtain alumina powder. In high-speed mixer mixing, mixing was performed for 30 seconds using a batch type mill (A10 manufactured by IKA, rotation speed: 20,000 rpm) to obtain a mixed powder as alumina powder. In addition, in the planetary stirring mixing, mixing was performed for 30 seconds using an autorotation/revolution mixer (ARV-310, rotation speed 2000 rpm) to obtain a mixed powder as alumina powder.
　得られたアルミナ粉末を用い、下記の通り、アルミナ粉末の粒度分布測定等を行った。 Using the obtained alumina powder, the particle size distribution of the alumina powder was measured as described below.
　〔アルミナ粉末の粒度分布測定〕
　（粒度分布測定用樹脂組成物の作製）
　まず粒度分布測定用樹脂組成物として、表１に示すアルミナ粉末と、エポキシ樹脂とを混合・混錬して成型体を得た。エポキシ樹脂は、樹脂１（５３型エポキシ主剤（株式会社三啓製））と、樹脂２（５３型エポキシ硬化剤（株式会社三啓製））とを２：１の比率（質量比率）で混合したものを用いた。各アルミナ粉末とエポキシ樹脂を、粉末充填率が８５質量％になるように計量し、株式会社シンキー製の自転・公転ミキサー（ＡＲＶ－３１０）を用いて混合および混錬し、室温で２４時間硬化させて成型体（硬化物）を得た。 [Particle size distribution measurement of alumina powder]
(Preparation of resin composition for particle size distribution measurement)
First, as a resin composition for particle size distribution measurement, alumina powder shown in Table 1 and an epoxy resin were mixed and kneaded to obtain a molded body. The epoxy resin is a mixture of resin 1 (type 53 epoxy main agent (manufactured by Sankei Co., Ltd.)) and resin 2 (type 53 epoxy curing agent (manufactured by Sankei Co., Ltd.)) at a ratio of 2:1 (mass ratio). I used the one I made. Each alumina powder and epoxy resin were weighed so that the powder filling rate was 85% by mass, mixed and kneaded using a rotation/revolution mixer (ARV-310) manufactured by Shinky Co., Ltd., and cured at room temperature for 24 hours. A molded product (cured product) was obtained.
　（粒度分布測定）
　得られた成型体に対し、クロスセクションポリッシャ（登録商標、日本電子株式会社製ＳＭ－０９０１０）を用い、イオンビームによる断面の研磨加工として加速電圧６．０ｋＶで１２時間の加工を行い、断面サンプルを得た。 (Particle size distribution measurement)
The obtained molded body was polished using a cross section polisher (registered trademark, SM-09010 manufactured by JEOL Ltd.) using an ion beam at an acceleration voltage of 6.0 kV for 12 hours, and a cross-sectional sample was obtained. I got it.
　得られた断面サンプルを、カーボンテープ上に固定し、走査型電子顕微鏡（ＳＥＭ、株式会社日立ハイテクノロジーズ製、品番：Ｓ－４８００）を用いて、ＳＥＭ画像を、所定の加速電圧で２０，０００倍のＳＥＭ画像を取得した。そして取得したＳＥＭ画像を用い、画像解析ソフト（ＩｍａｇｅＪ）を用いて自動二値化処理し、粒子を抽出した画像を取得した。二値化処理の一例を図４に示す。図４では、図４ＡのＳＥＭ画像を二値化処理することで、図４Ｂに示す二値化処理した画像が得られることを示す。なお、解析範囲からはみ出す粒子は解析対象から除外した。抽出された粒子について、粒子分離処理（上記画像解析ソフト「ＩｍａｇｅＪ」の場合は「Ｗａｔｅｒｓｈｅｄ処理」）を実施し、各粒子の面積から円相当径を算出した。そして、個数基準の累積粒度分布の微粒側から累積１０％の粒径Ｄ１０と、個数基準の累積粒度分布の微粒側から累積１００％の粒径Ｄ１００と、個数基準の累積粒度分布の微粒側から累積５０％の粒径Ｄ５０とを算出した。更にこれらの算出値を用い、下記式（１ａ）から、各例のスパン値を算出した。その結果を表２に示す。
　スパン値＝（Ｄ１００－Ｄ１０）／Ｄ５０・・・（１ａ） The obtained cross-sectional sample was fixed on a carbon tape, and an SEM image was taken using a scanning electron microscope (SEM, manufactured by Hitachi High-Technologies Corporation, product number: S-4800) at a predetermined acceleration voltage of 20,000 Double SEM images were acquired. The obtained SEM image was then automatically binarized using image analysis software (ImageJ) to obtain an image in which particles were extracted. An example of the binarization process is shown in FIG. FIG. 4 shows that the binarized image shown in FIG. 4B is obtained by binarizing the SEM image in FIG. 4A. Note that particles that protrude from the analysis range were excluded from the analysis target. The extracted particles were subjected to particle separation processing ("Watershed processing" in the case of the above-mentioned image analysis software "ImageJ"), and the equivalent circle diameter was calculated from the area of each particle. Then, the cumulative particle size D10 of 10% from the fine particle side of the number-based cumulative particle size distribution, the particle size D100 of 100% cumulative particle size from the fine particle side of the number-based cumulative particle size distribution, and the particle size D100 of 100% cumulative particle size from the fine particle side of the number-based cumulative particle size distribution. The cumulative 50% particle size D50 was calculated. Furthermore, using these calculated values, the span value of each example was calculated from the following formula (1a). The results are shown in Table 2.
Span value = (D100-D10)/D50...(1a)
　〔円相当径が０．３μｍ未満の粒子の平均円形度の測定〕
　上記粒度分布測定において、円相当径が０．３μｍ未満の粒子の面積、周囲長をそれぞれ算出した。そして、下記式（２）により円相当径が０．３μｍ未満の各粒子の円形度を算出した。該算出結果から、円相当径が０．３μｍ未満の粒子の平均円形度を求めた。その結果を表２に示す。
　粒子１粒の円形度＝４×π×面積／（周囲長２）・・・（２） [Measurement of average circularity of particles with equivalent circle diameter of less than 0.3 μm]
In the above particle size distribution measurement, the area and circumference length of particles having an equivalent circular diameter of less than 0.3 μm were calculated. Then, the circularity of each particle having an equivalent circle diameter of less than 0.3 μm was calculated using the following formula (2). From the calculation results, the average circularity of particles having an equivalent circular diameter of less than 0.3 μm was determined. The results are shown in Table 2.
Circularity of one particle = 4 x π x area / (perimeter 2 )... (2)
　〔円相当径が０．３μｍ未満の粒子数と、円相当径が０．３μｍ以上の粒子数の粒子比率（Ｎａ／Ｎｂ）の変動係数ＣＶ（Ｎａ／Ｎｂ）の測定〕
　円相当径が０．３μｍ未満の粒子数Ｎａと、円相当径が０．３μｍ以上の粒子数Ｎｂの粒子比率（Ｎａ／Ｎｂ）の変動係数ＣＶ（Ｎａ／Ｎｂ）は、以下の方法で求めた。 [Measurement of the coefficient of variation CV (Na/Nb) of the particle ratio (Na/Nb) between the number of particles with an equivalent circle diameter of less than 0.3 μm and the number of particles with an equivalent circle diameter of 0.3 μm or more]
The coefficient of variation CV (Na/Nb) of the particle ratio (Na/Nb) between the number of particles Na with an equivalent circle diameter of less than 0.3 μm and the number Nb of particles with an equivalent circle diameter of 0.3 μm or more is determined by the following method. Ta.
　上記断面サンプルを用いて、ＳＥＭで１０，０００倍の画像を５視野において取得し（倍率１０，０００倍）、前記粒度分布測定の場合と同様に、画像解析ソフト（ＩｍａｇｅＪ）を用いて、自動二値化処理により粒子を抽出した画像を取得した。なお、解析範囲からはみ出すような粒子は除外した。抽出された粒子について、粒子分離処理（上記画像解析ソフト「ＩｍａｇｅＪ」の場合は「Ｗａｔｅｒｓｈｅｄ処理」）を実施し、各粒子の面積から円相当径を算出し、０．３μｍ未満の粒子数Ｎａと０．３μｍ以上の粒子数Ｎｂを測定した。５視野のＮａ／Ｎｂを測定し、Ｎａ／Ｎｂの平均値、標準偏差、変動係数ＣＶを求めた。各視野のＮａ／Ｎｂを求めて、複数視野のＮａ／Ｎｂの平均値と標準偏差を求めた。そして粒子比率（Ｎａ／Ｎｂ）の標準偏差を、粒子比率（Ｎａ／Ｎｂ）の平均値で除して、粒子比率（Ｎａ／Ｎｂ）の変動係数ＣＶ（Ｎａ／Ｎｂ）を求めた。その結果を表２に示す。 Using the above cross-sectional sample, images of 10,000 times magnification were acquired in 5 fields of view using SEM (magnification: 10,000 times), and as in the case of particle size distribution measurement, automatic analysis was performed using image analysis software (ImageJ). An image in which particles were extracted was obtained by binarization processing. Note that particles that were outside the analysis range were excluded. The extracted particles are subjected to particle separation processing ("Watershed processing" in the case of the above-mentioned image analysis software "ImageJ"), and the equivalent circle diameter is calculated from the area of each particle, and the number Na of particles less than 0.3 μm is calculated. The number Nb of particles of 0.3 μm or more was measured. Na/Nb was measured in 5 visual fields, and the average value, standard deviation, and coefficient of variation CV of Na/Nb were determined. Na/Nb of each field of view was determined, and the average value and standard deviation of Na/Nb of multiple fields of view were determined. Then, the standard deviation of the particle ratio (Na/Nb) was divided by the average value of the particle ratio (Na/Nb) to obtain the coefficient of variation CV (Na/Nb) of the particle ratio (Na/Nb). The results are shown in Table 2.
　なお本実施例では、便宜上、得られたアルミナ粉末を少量の樹脂と混合した状態で変動係数ＣＶ（Ｎａ／Ｎｂ）を評価しているが、その評価結果は、上記樹脂が存在しない状態と同様の分散状態を示すと考えられる。つまり、上記測定結果は、アルミナ粉末の分散状態を示しているといえる。 In this example, for convenience, the coefficient of variation CV (Na/Nb) was evaluated in a state where the obtained alumina powder was mixed with a small amount of resin, but the evaluation results were the same as in the state where no resin was present. This is considered to indicate the state of dispersion. In other words, the above measurement results can be said to indicate the dispersion state of the alumina powder.
　〔１０μｍ以上の粗粒の有無〕
　上記断面サンプルにおいて、ＳＥＭで１，０００倍の画像を５視野において取得し、該画像にて短径が１０μｍ以上の粗粒の有無を確認した。その結果を表２に示す。 [Presence or absence of coarse particles of 10 μm or more]
In the above cross-sectional sample, images of 1,000 times magnification were acquired in 5 fields of view using SEM, and the presence or absence of coarse particles with a short axis of 10 μm or more was confirmed in the images. The results are shown in Table 2.
　なお、断面サンプルのＳＥＭ画像の一例として、実施例１の断面サンプルのＳＥＭ画像を図５と図６に示す。また、アルミナ原料粒子は実施例１と同じであるが混合方法の異なる比較例１の断面サンプルのＳＥＭ画像を、図７と図８に示す。更に、比較例３の断面サンプルのＳＥＭ画像を図９に示す。これらの写真において、黒い部分は樹脂を示す。図７と図８の白破線で囲んだ部分は、凝集粒が生じている領域であることを示す。また図９では、アルミナ粉末として、アルミナ原料粒子１のみを使用しており、アルミナ大粒子の隙間が充填されていない。それに対して、本実施形態のアルミナ粉末に該当する実施例１のアルミナ粉末のＳＥＭ写真（図５、図６）では、アルミナ原料粒子１由来のアルミナ大粒子の隙間が、アルミナ原料粒子２由来のアルミナ小粒子で充填されている。この様な形態が実現することで、熱伝導パスが増えて熱伝導性が高まり、放熱性に優れたフィラーとして使用することができる。 As an example of the SEM image of the cross-sectional sample, SEM images of the cross-sectional sample of Example 1 are shown in FIGS. 5 and 6. Further, FIGS. 7 and 8 show SEM images of a cross-sectional sample of Comparative Example 1, in which the alumina raw material particles were the same as those in Example 1 but the mixing method was different. Further, a SEM image of a cross-sectional sample of Comparative Example 3 is shown in FIG. In these photographs, the black parts indicate resin. The area surrounded by the white broken line in FIGS. 7 and 8 indicates the area where aggregated particles are generated. Further, in FIG. 9, only alumina raw material particles 1 are used as the alumina powder, and gaps between large alumina particles are not filled. In contrast, in the SEM photographs (FIGS. 5 and 6) of the alumina powder of Example 1, which corresponds to the alumina powder of this embodiment, the gap between the large alumina particles derived from alumina raw material particle 1 is different from that of alumina raw material particle 2. Filled with alumina small particles. By realizing such a configuration, the number of heat conduction paths increases, the thermal conductivity increases, and the material can be used as a filler with excellent heat dissipation properties.
　〔樹脂組成物における粘度の測定〕
　（粘度測定用樹脂組成物の作製）
　各例のアルミナ粉末と樹脂１（５３型エポキシ主剤、株式会社三啓製）を用意した。そして、各例のアルミナ粉末を１０ｇと、樹脂１を２．５ｇとをそれぞれ計量し、株式会社シンキー製の自転・公転ミキサー（ＡＲＶ－３１０）を用いて混合および混錬し、粘度測定用樹脂組成物を作製した。 [Measurement of viscosity in resin composition]
(Preparation of resin composition for viscosity measurement)
Alumina powder and Resin 1 (type 53 epoxy base resin, manufactured by Sankei Co., Ltd.) of each example were prepared. Then, 10 g of the alumina powder of each example and 2.5 g of Resin 1 were weighed, mixed and kneaded using an autorotation/revolution mixer (ARV-310) manufactured by Shinky Co., Ltd., and the resin for viscosity measurement was A composition was prepared.
　（粘度測定用樹脂組成物の粘度の測定）
　得られた粘度測定用樹脂組成物を用い、動的粘弾性測定装置（ユービーエム社製「Ｒｈｅｏｓｏｌ－Ｇ３０００」）を使用して、粘度を測定した。直径４０ｍｍのパラレルプレートを使用し、ギャップ１ｍｍ、せん断速度５ｓ－１、２５℃の条件で測定した。 (Measurement of viscosity of resin composition for viscosity measurement)
Using the obtained resin composition for viscosity measurement, the viscosity was measured using a dynamic viscoelasticity measuring device ("Rheosol-G3000" manufactured by UBM). The measurement was performed using a parallel plate with a diameter of 40 mm, with a gap of 1 mm, a shear rate of 5 s -1 , and 25° C.
　〔樹脂組成物の熱伝導率の測定〕
　（熱伝導率測定用樹脂組成物の作製）
　各例のアルミナ粉末と、樹脂として、樹脂１（５３型エポキシ主剤、株式会社三啓製）と樹脂２（５３型エポキシ硬化剤、株式会社三啓製）を用意した。樹脂１と樹脂２を２：１の比率（質量比率）となるように混合し、エポキシ樹脂を得た。各アルミナ粉末９ｇと、エポキシ樹脂１ｇとをカップに計量し、株式会社シンキー製の自転・公転ミキサー（ＡＲＶ－３１０）を用いて混合および混錬し、熱伝導率測定用樹脂組成物を得た。 [Measurement of thermal conductivity of resin composition]
(Preparation of resin composition for thermal conductivity measurement)
Alumina powder of each example and resins Resin 1 (type 53 epoxy base agent, manufactured by Sankei Co., Ltd.) and Resin 2 (type 53 epoxy curing agent, manufactured by Sankei Co., Ltd.) were prepared. Resin 1 and resin 2 were mixed at a ratio (mass ratio) of 2:1 to obtain an epoxy resin. 9 g of each alumina powder and 1 g of epoxy resin were weighed into a cup, and mixed and kneaded using a rotation/revolution mixer (ARV-310) manufactured by Shinky Co., Ltd. to obtain a resin composition for measuring thermal conductivity. .
　（熱伝導率測定用樹脂組成物の熱伝導率の測定）
　得られた熱伝導率測定用樹脂組成物を、直径２０ｍｍの金型に２ｇ入れ、３０ＭＰａの圧力を加えて成型し、室温で２４時間置いて樹脂を硬化させた。次いで、硬化した成型体を１０ｍｍ角×厚さ２ｍｍのサイズに加工し、表面研磨して試験片を得た。この試験片の厚み方向の熱伝導率を、キセノンフラッシュアナライザー（ＮＥＴＺＳＣＨ社製、ＬＦＡ４６７）を用い、レーザーフラッシュ法で測定した。測定は、大気雰囲気下、２５℃の条件下で行った。そして、熱伝導率が２．０以上であるものを高熱伝導性であると評価し、熱伝導率が２．０未満であるものを低熱伝導性であると評価した。その結果を表３に示す。 (Measurement of thermal conductivity of resin composition for measuring thermal conductivity)
2 g of the obtained resin composition for measuring thermal conductivity was put into a mold with a diameter of 20 mm, molded under a pressure of 30 MPa, and left at room temperature for 24 hours to harden the resin. Next, the cured molded body was processed into a size of 10 mm square x 2 mm thick, and the surface was polished to obtain a test piece. The thermal conductivity in the thickness direction of this test piece was measured by a laser flash method using a xenon flash analyzer (manufactured by NETZSCH, LFA467). The measurements were carried out under atmospheric conditions at 25°C. Those with a thermal conductivity of 2.0 or more were evaluated as having high thermal conductivity, and those with a thermal conductivity of less than 2.0 were evaluated as having low thermal conductivity. The results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表１～３の結果から次のことがわかる。実施例１～３は、アルミナ粉末の形状が本実施形態で規定する範囲内にあるため、熱伝導性が高く、かつ１０μｍ以上の粗粒が存在せず、薄膜状の熱伝導性部材を実現できる。それに対して、比較例１は、変動係数ＣＶ（Ｎａ／Ｎｂ）が高く、１０μｍ以上の粗粒が存在しており、粘度が測定できないほど高く、熱伝導率も低かった。更に１０μｍ以上の粗粒が存在するため、薄膜状の熱伝導性部材を実現できないものとなった。比較例２は、変動係数ＣＶ（Ｎａ／Ｎｂ）が高く、１０μｍ以上の粗粒が存在しており、薄膜状の熱伝導性部材を実現できないものとなった。比較例３は、Ｄ１０とスパン値が規定の範囲を外れており、粘度が測定できないほど高く、熱伝導率も低かった。 The following can be seen from the results in Tables 1 to 3. In Examples 1 to 3, the shape of the alumina powder is within the range specified in this embodiment, so the thermal conductivity is high and there are no coarse particles of 10 μm or more, realizing a thin film-like thermally conductive member. can. On the other hand, in Comparative Example 1, the coefficient of variation CV (Na/Nb) was high, coarse particles of 10 μm or more were present, the viscosity was so high that it could not be measured, and the thermal conductivity was also low. Furthermore, since coarse grains of 10 μm or more were present, a thin film-like thermally conductive member could not be realized. In Comparative Example 2, the coefficient of variation CV (Na/Nb) was high and coarse particles of 10 μm or more were present, making it impossible to realize a thin film-like thermally conductive member. In Comparative Example 3, the D10 and span values were out of the specified range, the viscosity was so high that it could not be measured, and the thermal conductivity was also low.
　本出願は、日本国特許出願である特願２０２２－１２４９９９号を基礎出願とする優先権主張を伴う。特願２０２２－１２４９９９号は参照することにより本明細書に取り込まれる。 This application claims priority to Japanese Patent Application No. 2022-124999, which is a Japanese patent application, as the basic application. Japanese Patent Application No. 2022-124999 is incorporated herein by reference.

Claims (6)

  1. 　円相当径が０．３μｍ未満のアルミナ粒子を有するアルミナ粉末であって、
    　個数基準の累積粒度分布の微粒側から累積１０％の粒径Ｄ１０が０．１５μｍ未満であり、
    　前記Ｄ１０と、個数基準の累積粒度分布の微粒側から累積１００％の粒径Ｄ１００と、個数基準の累積粒度分布の微粒側から累積５０％の粒径Ｄ５０とが、下記式（１）を満たし、
    　倍率１０，０００倍で少なくとも５視野観察したときに、円相当径が０．３μｍ未満のアルミナ粒子数Ｎａと円相当径が０．３μｍ以上のアルミナ粒子数Ｎｂの粒子比率（Ｎａ／Ｎｂ）の変動係数であるＣＶ（Ｎａ／Ｎｂ）が０．３以下である、アルミナ粉末。
    　４．０≦（Ｄ１００－Ｄ１０）／Ｄ５０≦２０　・・・（１）     An alumina powder having alumina particles having an equivalent circle diameter of less than 0.3 μm,
    The cumulative particle size D10 of 10% from the fine particle side of the number-based cumulative particle size distribution is less than 0.15 μm,
    The above D10, the cumulative particle size D100 of 100% from the fine particle side of the number-based cumulative particle size distribution, and the cumulative particle size D50 of 50% from the fine particle side of the number-based cumulative particle size distribution satisfy the following formula (1). ,
    When observing at least 5 fields of view at a magnification of 10,000 times, the particle ratio (Na/Nb) of the number of alumina particles Na with an equivalent circle diameter of less than 0.3 μm and the number Nb of alumina particles with an equivalent circle diameter of 0.3 μm or more was determined. Alumina powder having a coefficient of variation (CV(Na/Nb)) of 0.3 or less.
    4.0≦(D100-D10)/D50≦20...(1)
  2. 　前記円相当径が０．３μｍ未満のアルミナ粒子は、平均円形度が０．８２以上である、請求項１に記載のアルミナ粉末。 The alumina powder according to claim 1, wherein the alumina particles having an equivalent circle diameter of less than 0.3 μm have an average circularity of 0.82 or more.
  3. 　前記円相当径が０．３μｍ未満のアルミナ粒子は、αアルミナ粒子である、請求項２に記載のアルミナ粉末。 The alumina powder according to claim 2, wherein the alumina particles having an equivalent circle diameter of less than 0.3 μm are α-alumina particles.
  4. 　請求項１～３のいずれかに記載のアルミナ粉末と樹脂を含む、樹脂組成物。 A resin composition comprising the alumina powder according to any one of claims 1 to 3 and a resin.
  5. 　前記アルミナ粉末と樹脂の質量割合が８５：１５～９５：５の範囲である請求項４に記載の樹脂組成物。 The resin composition according to claim 4, wherein the mass ratio of the alumina powder to the resin is in the range of 85:15 to 95:5.
  6. 　円相当径が０．３μｍ未満のアルミナ原料粒子と、円相当径が０．３μｍ以上のアルミナ原料粒子を含む配合原料を準備する原料準備工程と、
    　前記配合原料を、回転速度が１００００ｒｐｍ以上である高速ミキサーを用いて混合する混合工程とを有する、アルミナ粉末の製造方法。     a raw material preparation step of preparing a blended raw material containing alumina raw material particles with an equivalent circle diameter of less than 0.3 μm and alumina raw material particles with an equivalent circle diameter of 0.3 μm or more;
    A method for producing alumina powder, comprising a mixing step of mixing the blended raw materials using a high-speed mixer having a rotation speed of 10,000 rpm or more.
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JPH0789759A (en) * 1993-07-27 1995-04-04 Sumitomo Chem Co Ltd Alumina for tape cast, alumina composition, alumina green sheet, alumina sintered plate and its production
JP2008532898A (en) * 2005-03-09 2008-08-21 デグサ ノヴァラ テクノロジー ソチエタ ペル アツィオーニ Monolith production method by sol-gel method
CN102009993A (en) * 2010-12-15 2011-04-13 中国铝业股份有限公司 Method for preparing submicron aluminium oxide by two-stage roasting method
JP2012067205A (en) * 2010-09-24 2012-04-05 Hitachi Chemical Co Ltd High heat radiation insulating resin sheet and method of manufacturing the same
WO2018047871A1 (en) * 2016-09-09 2018-03-15 住友化学株式会社 Alumina powder, alumina slurry, alumina-containing coating layer, multilayer separation membrane and secondary battery
JP2020033335A (en) * 2018-08-23 2020-03-05 ポーラ化成工業株式会社 Vesicle-containing composition
JP2020169279A (en) * 2019-04-04 2020-10-15 関西ペイント株式会社 Conductive pigment paste

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0789759A (en) * 1993-07-27 1995-04-04 Sumitomo Chem Co Ltd Alumina for tape cast, alumina composition, alumina green sheet, alumina sintered plate and its production
JP2008532898A (en) * 2005-03-09 2008-08-21 デグサ ノヴァラ テクノロジー ソチエタ ペル アツィオーニ Monolith production method by sol-gel method
JP2012067205A (en) * 2010-09-24 2012-04-05 Hitachi Chemical Co Ltd High heat radiation insulating resin sheet and method of manufacturing the same
CN102009993A (en) * 2010-12-15 2011-04-13 中国铝业股份有限公司 Method for preparing submicron aluminium oxide by two-stage roasting method
WO2018047871A1 (en) * 2016-09-09 2018-03-15 住友化学株式会社 Alumina powder, alumina slurry, alumina-containing coating layer, multilayer separation membrane and secondary battery
JP2020033335A (en) * 2018-08-23 2020-03-05 ポーラ化成工業株式会社 Vesicle-containing composition
JP2020169279A (en) * 2019-04-04 2020-10-15 関西ペイント株式会社 Conductive pigment paste

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