JP6393956B2 - Zinc oxide, its production method and its use - Google Patents

Description

  The present invention relates to zinc oxide, a method for producing the same, and uses thereof.

  Zinc oxide is a white pigment, UV shielding material, thermally conductive filler, filler, adsorbent, photocatalyst, catalyst, ceramic material, conductive material, piezoelectric material, gas sensor, electrophotographic photosensitive material, varistor, phosphor, emitter, It is used for various applications such as electronic devices, and is used in cosmetics, external preparations, paints, resin compositions, heat-dissipating compositions and the like.

  In order to produce zinc oxide, for example, a method of producing zinc oxide directly in a liquid by neutralizing a solution containing a zinc salt with an alkali neutralizer is known (see Patent Document 1). Further, in Patent Document 2, an aqueous solution containing a zinc salt and a precipitating agent are mixed in 1 second to 15 minutes while stirring with a Reynolds number of 30 or more when directly producing the zinc oxide, and the pH is 11 or more. To produce a flaky zinc oxide powder having an average particle size of 0.1 to 0.88 μm, an average particle thickness of 0.01 to 0.2 μm, and an average plate ratio of 3 or more It is also disclosed that water-soluble organic substances such as citric acid and ethanolamine are allowed to coexist in the precipitation. In Example 14 of Patent Document 2, 1 g of citric acid (corresponding to 0.024 in terms of the molar ratio of the carboxyl group (—COOH) to the zinc atom of the zinc compound), and in Example 13, 10 g of salicylic acid (zinc of the zinc compound) A flaky zinc oxide powder is produced by adding a carboxyl group (-COOH) molar ratio with respect to atoms and corresponding to 0.12.

  Patent Document 3 discloses a carboxylic acid of 0.2 or more in terms of a molar ratio of the total amount of a zinc compound and a carboxyl group (—COOH) and a salt thereof (—COOM) to a zinc atom of the zinc compound. Or a salt thereof and an alkali metal compound are mixed to precipitate zinc oxide, and the amount of the alkali metal compound is carboxylic acid and / or a salt thereof when the valence of the alkali metal compound is n. And (2X + 0.001) / n to (4X + 0.2) / n (mol / liter) with respect to the zinc concentration X (mol / liter) of the zinc compound and neutralizing the carboxyl group (—COOH) present in It is disclosed that a zinc oxide particle having a shape similar to a sphere, preferably a shape similar to a sphere, can be obtained by accumulating plate-like zinc oxide particles by using the total amount in the range of .

JP-A-53-116296 Japanese Patent No. 2683389 JP 2008-254989 A

  In the prior art, zinc oxide having a flake-like or needle-like particle shape is obtained by neutralizing a solution containing a zinc salt with an alkali neutralizing agent such as sodium hydroxide or ammonia and directly depositing zinc oxide. It can be produced, or an aggregated body having a spherical shape in which zinc oxide particles having a plate-like shape are accumulated is obtained. However, the zinc oxide of Patent Document 1 has problems such as large variation in particle diameter and shape and low crystallinity. The flaky zinc oxide of Patent Document 2 has problems such as high bulk density and low filling properties. In addition, the zinc oxide aggregate of Patent Document 3 has a problem that it tends to be aggregated particles and has a high bulk density and a low filling property.

  Zinc oxide is required to be controlled in shape, size, crystallinity, etc., depending on its application. For example, when it is used as a thermally conductive filler, filler, ceramic raw material, etc., since the bulk density of flaky or needle-like particles is high, zinc oxide having a low bulk density and good fillability is required. In addition, when used as a heat conductive filler, a photocatalyst, a catalyst, a ceramic raw material, a conductive material, a piezoelectric material, etc., zinc oxide having good crystallinity in addition to filling properties is required. In addition, zinc oxide with good dispersibility is required when used in cosmetics, external preparations, paints, resin compositions, heat dissipating compositions and the like.

  As a result of searching for a method for controlling the particle shape, particle diameter, and the shape and size of the aggregate of zinc oxide, the present inventors have found that a zinc compound, a carboxylic acid and / or a salt thereof, and an alkali metal compound In which zinc oxide is precipitated, wherein the amount of the carboxylic acid and / or its salt is the total amount of the carboxyl group (—COOH) and its salt (—COOM) relative to the zinc atom of the zinc compound. When the molar ratio L is 0.2 or more and the amount L (mol / liter) of the alkali metal compound is n and the valence of the zinc atom of the zinc compound is m, zinc When an amount that is in the range of mX / n or less with respect to the concentration X (mol / liter) is used, a shape similar to a sphere formed by a plane of a plurality of zinc oxide particles having a columnar or plate-like particle shape is formed. Obtaining zinc oxide It is, found such that the zinc oxide of similar shape to the soccer ball is obtained, and have completed the present invention.

That is, the present invention
(1) Zinc oxide formed with a plane of a plurality of zinc oxide particles having a columnar or plate-like particle shape,
(2) A method of depositing zinc oxide by mixing a zinc compound, a carboxylic acid and / or salt thereof, and an alkali metal compound,
The amount of the carboxylic acid and / or salt thereof is 0.2 or more in terms of the molar ratio of the total amount of the carboxyl group (—COOH) and the salt thereof (—COOM) to the zinc atom of the zinc compound,
The amount L (mol / liter) of the alkali metal compound is such that the valence of the alkali metal compound is n and the valence of the zinc atom of the zinc compound is m. a method for producing zinc oxide, characterized in that the amount is in the range of n or less,
(3) a thermally conductive filler containing the zinc oxide, a heat dissipating composition containing the thermally conductive filler,
(4) An ultraviolet shielding material containing the zinc oxide, a cosmetic containing the ultraviolet shielding agent, and the like.

The zinc oxide of the present invention is zinc oxide formed by a plane of a plurality of zinc oxide particles having a columnar or plate-like particle shape, the shape and size are uniform, the crystallinity and dispersibility are good, and the bulk density is high. Since it is low and has good filling properties, it can be used for thermally conductive fillers, fillers, white pigments, ceramic raw materials, etc., and can be blended in cosmetics, external preparations, paints, resin compositions, heat dissipation compositions, etc. it can. When it is blended in cosmetics, it has a specific size, so that the dispersibility is good and the slipperiness to the skin is improved.
In addition, the method for producing zinc oxide of the present invention can precipitate zinc oxide by mixing a zinc compound, a specific amount of carboxylic acid and / or a salt thereof, and a specific amount of an alkali metal compound, It can be manufactured with high productivity.

2 is an electron micrograph of zinc oxide (sample A) produced in Example 1. 2 is an electron micrograph of zinc oxide (sample B) obtained in Comparative Example 1.

  The zinc oxide of the present invention contains at least 50% by weight of ZnO exhibiting an X-ray diffraction pattern of any one of hexagonal, cubic and cubic face-centered structures. Zinc hydroxide and zinc sulfate used in production Zinc compounds such as zinc nitrate, zinc chloride, and zinc acetate may be contained. It may also contain sulfate radicals, nitrate radicals, chlorine, acetic acid, etc. that comprised the zinc compounds used in the production, and also includes materials such as carboxylic acids, their salts, and alkali metal compounds. May be. Furthermore, the surface of the zinc oxide particles may be coated with a surface treatment agent of an inorganic compound such as silica or alumina or an organic compound such as siloxane.

  The zinc oxide of the present invention is a collection of a plurality of zinc oxide particles having a columnar or plate-like particle shape, and is composed of columnar and plate-like flat surfaces (bottom surface or top surface) of zinc oxide particles. If the zinc oxide particles are hexagonal columnar bodies, they are composed of a plurality of hexagonal surfaces. For this reason, the zinc oxide aggregate can form a shape similar to a sphere composed of a polyhedron or a shape close to a sphere. Such a shape may be, for example, a shape similar to a soccer ball. A soccer ball is usually composed of a plurality of regular pentagons and regular hexagons. However, the soccer ball includes not only such a structure but also a plurality of hexagons. Or a polyhedral spherical similar shape composed of a plurality of circles, ellipses, or the like. The number of polyhedrons forming the zinc oxide aggregate can be appropriately set, preferably 10 or more, more preferably about 10 to 30, more preferably 12 to 25, and still more preferably 14 to 20. . There may be a gap between the planes, or there may be no gap. The average particle diameter of such an aggregate can be set as appropriate, preferably 0.5 to 20 μm, and more preferably 1 to 20 μm. The shape and size (crossover diameter) of the columnar or plate-like zinc oxide particles can be observed with an electron microscope, and the side that can be observed toward the surface is the size (crossover diameter) of 0.01 to 2.0 μm. The range is more preferable, the range of 0.05 to 1.0 μm is more preferable, and the range of 0.2 to 0.8 μm is still more preferable. These shapes and sizes are observed with an electron microscope, and the average particle size and size (crossover diameter) are calculated by measuring about 100 pieces.

  The method for producing zinc oxide according to the present invention is a method in which a zinc compound, a carboxylic acid and / or salt thereof, and an alkali metal compound are mixed to precipitate zinc oxide, wherein the carboxylic acid and / or salt thereof is precipitated. The amount is 0.2 or more in terms of the molar ratio of the total amount of the carboxyl group (—COOH) and its salt (—COOM) to the zinc atom of the zinc compound, and the amount L (mol / liter) of the alkali metal compound is In addition, when the valence of the alkali metal compound is n and the valence of the zinc atom of the zinc compound is m, the amount is in the range of mX / n or less with respect to the zinc concentration X (mol / liter). And Any zinc compound can be used as long as it is water-soluble. For example, zinc sulfate, zinc nitrate, zinc chloride, zinc acetate, and the like can be used. Zinc sulfate is preferable because zinc oxide particles having various shapes and aggregates having various shapes in which the zinc oxide particles are easily collected can be obtained. Moreover, even if it does not melt | dissolve in neutral water, such as metallic zinc, a zinc oxide, and zinc hydroxide, if it is a compound which melt | dissolves in an acid and an alkali metal compound, it can use similarly to said zinc compound.

The carboxylic acid is a compound having a carboxyl group, and can be used without limitation. For example, the following can be used, and in particular, citric acid and / or a salt thereof is used to form a polyhedron. This is preferable because a zinc oxide aggregate having a shape similar to a sphere can be produced.
(1) Polycarboxylic acids, particularly dicarboxylic acids and tricarboxylic acids such as oxalic acid and fumaric acid.
(2) Hydroxypolycarboxylic acids, especially hydroxydi- or hydroxytri-carboxylic acids such as malic acid, citric acid or tartronic acid.
(3) (Polyhydroxy) monocarboxylic acid, such as glucoheptonic acid or gluconic acid.
(4) Poly (hydroxycarboxylic acid) such as tartaric acid.
(5) Dicarboxyl amino acids and their corresponding amides, such as aspartic acid, asparagine or glutamic acid.
(6) A hydroxylated or non-hydroxylated monocarboxyl amino acid such as lysine, serine or threonine.
As the carboxylate, any salt can be used without limitation. For example, alkali metal salts such as sodium and potassium, ammonium salts and the like can be used. The amount of the carboxylic acid and / or salt thereof is the total molar amount of the carboxyl group (—COOH) and the salt thereof (—COOM, where M represents an alkali metal, ammonium, etc.) relative to the zinc atom of the zinc compound. This is because the total amount of the carboxyl group (—COOH) and its salt (—COOM) affects the particle shape of zinc oxide and the like. For example, citric acid has three carboxylic groups in one molecule, and therefore has an influence of three. In terms of the molar ratio, the carboxyl group and / or salt thereof should be 0.2 or more with respect to the zinc atom of the zinc compound, and the amount in the range of 0.2 to 10 is preferable, and 1.0 to 5. A range of 0 is more preferred. If the molar ratio of the carboxyl group is less than 0.2, the effect of addition is difficult to obtain, which is not preferable.

  The alkali metal compound may be appropriately used as long as it is water-soluble and exhibits alkalinity. Examples thereof include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, sodium carbonate and potassium carbonate. An alkali metal carbonate, an acetate such as sodium acetate, and the like are preferably used. The amount L (mol / liter) of the alkali metal compound is such that the valence of the alkali metal compound is n and the valence of the zinc atom of the zinc compound is m. An amount in the range of n or less is preferable because a desired zinc oxide can be produced, and is preferably in a range of 0.5 · mX / n to 0.9 · mX / n (50 to 90% of mX / n). ) Is more preferable, and a range of 0.7 · mX / n to 0.9 · mX / n (70 to 90% of mX / n) is more preferable.

An aqueous solution of the zinc compound, a carboxylic acid and / or a salt thereof, and an alkali metal compound are mixed. Specifically, an alkali metal compound or an aqueous solution thereof may be added to and mixed with a mixed solution of an aqueous zinc compound solution and a carboxylic acid and / or a salt thereof, or zinc may be added to the alkali metal compound or an aqueous solution thereof with stirring. Each solution or mixed solution of the compound aqueous solution and the carboxylic acid and / or salt thereof may be added and mixed, but either the aqueous solution of the zinc compound and the carboxylic acid and / or salt thereof and the alkali metal compound or the aqueous solution thereof may be used. Also, it is preferable to mix while maintaining at 40 ° C. or lower. When the temperature is higher than 40 ° C, it is not preferable because zinc oxide is likely to be partially deposited and mixed in an uneven state by mixing with the alkali metal compound, and the preferable temperature is 10 to 40 ° C, and the more preferable temperature is 10 to 10 ° C. 30 ° C. A normal reaction tank, a pressure-resistant reaction tank, etc. can be used for heating. Stirring during heating can be carried out using a normal mixing and stirring means, for example, with a stirrer equipped with stirring blades. The operating conditions of the stirrer can be set as appropriate. For example, the rotational speed can be about 20 to 2000 rpm, and is preferably about 10 or more, more preferably about 10 to 50000, expressed by the following Reynolds coefficient.
Reynolds coefficient = (blade diameter) ² × stirring speed × solution density / solution viscosity The addition time can be appropriately set, but is preferably about 1 second to 1 hour, and more preferably about 1 second to 30 minutes. The pH is preferably adjusted to 7 or more by mixing with an alkali metal compound, but if it is lower than 7, it is difficult to obtain the desired zinc oxide. The preferred pH is about 8 to 13, more preferably about 11 to 13. After the alkali metal compound is mixed and adjusted to a predetermined pH to precipitate a precipitate, the pH may be maintained for about 10 minutes to 5 hours as necessary. In order to enhance crystallinity, the aqueous solution may be heated to 40 ° C. or higher, more preferably about 60 to 250 ° C., and still more preferably about 80 to 110 ° C. with stirring. After heating to a predetermined temperature, the temperature may be maintained for about 10 minutes to 10 hours as necessary.

  A mixed aqueous solution of a zinc compound and a carboxylic acid and / or a salt thereof and an alkali metal compound is further mixed with a salt such as sodium chloride, sodium sulfate, sodium nitrate, potassium chloride, potassium sulfate, potassium nitrate, ammonium chloride, ammonium sulfate, or ammonium nitrate. It is also possible to add salts to the aqueous zinc compound solution before mixing with the alkali metal compound. The amount of the salt added is preferably in the range of 0.0001 or more, and more preferably about 0.001 to 10 in terms of the molar ratio of the zinc compound to the zinc atom.

  The zinc oxide obtained in this manner is filtered and washed as necessary to separate into solid and liquid, and dried and dry pulverized to obtain zinc oxide powder. For solid-liquid separation, a filter that is usually used industrially, such as a filter press or a roll press, can be used. Band-type heaters, batch-type heaters, spray dryers, etc. are used for drying, impact-type crushers such as hammer mills and pin mills are used for dry-type crushing, grinding crushers such as roller mills, pulverizers, crushers, roll crushers, and jaw crushers. For example, a compression pulverizer such as a jet mill or an airflow pulverizer such as a jet mill can be used. Although a drying temperature can be set suitably, about 80-200 degreeC is suitable. Moreover, the said zinc oxide powder may be baked at the temperature of about 200-800 degreeC as needed, and since crystallinity can be improved further, it is preferable. Firing can usually be performed in an atmosphere of air, oxygen, nitrogen, etc., and the firing time is suitably about 10 minutes to 10 hours.

  The zinc oxide of the present invention can be provided with a coating layer of an oxide such as silicon, titanium, aluminum, zirconium and tin or an inorganic compound such as a phosphate thereof on the particle surface as necessary. Further, for the purpose of imparting dispersibility to solvents, paints, plastics, and the like, an organic compound may be coated, or both the inorganic compound and the organic compound may be coated. Examples of organic compounds include (1) organosilicon compounds ((a) organopolysiloxanes (dimethylpolysiloxane, methylhydrogen polysiloxane, methylmethoxypolysiloxane, methylphenylpolysiloxane, dimethylpolysiloxanediol, dimethylpolysiloxanedi). Hydrogen or the like or copolymers thereof), (b) organosilanes (aminosilane, epoxysilane, methacrylsilane, vinylsilane, mercaptosilane, chloroalkylsilane, alkylsilane, fluoroalkylsilane, etc. or their hydrolysis products) (C) organosilazanes (hexamethylsilazane, hexamethylcyclotrisilazane, etc.), (2) organometallic compounds ((a) organotitanium compounds (aminoalkoxytitanium, phosphoric acid ester titanium) , Carboxylic acid ester titanium, sulfonic acid ester titanium, titanium chelate, phosphite titanium complex, etc.), (b) organoaluminum compound (aluminum chelate, etc.), (c) organozirconium compound (carboxylate ester zirconium, zirconium chelate) Etc.), (3) polyols (trimethylolpropane, trimethylolethane, pentaerythritol, etc.), (4) alkanolamines (monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, triol) Propanolamine etc.) or derivatives thereof (acetate, oxalate, tartrate, formate, benzoate, etc. organic acid salts), (5) higher fatty acids (stearic acid, lauric acid, oleic acid) ) Or a metal salt thereof (aluminum salt, zinc salt, magnesium salt, calcium salt, barium salt, etc.), (6) higher hydrocarbons (paraffin wax, polyethylene wax, etc.) or derivatives thereof (perfluorinated products, etc.). These organic compounds may be used singly or in combination of two or more, and when used in cosmetics, it is preferable to use organopolysiloxanes and higher fatty acids. The coating amount of the organic compound is preferably in the range of 0.1 to 50% by weight, more preferably in the range of 0.1 to 30% by weight with respect to zinc oxide. In order to coat the compound, it can be coated in an aqueous slurry of zinc oxide by adding an inorganic compound or an organic compound and neutralizing the organic compound. As another method for coating the compound, an organic compound can be added and mixed in the dry pulverization described above.

  Since the zinc oxide of the present invention has an ultraviolet shielding ability, it is used as an ultraviolet shielding material. In addition, zinc oxide is used as an ultraviolet shielding material, a white pigment, a filler, and the like in an appropriate amount in cosmetics such as sunscreen cosmetics and basic cosmetics. For example, in addition to the above-mentioned zinc oxide, known components commonly used in cosmetics, for example, (1) solvents (water, lower alcohols, etc.), (2) oil agents (higher fatty acids, higher alcohols, organopolysiloxanes) (Silicone oil), hydrocarbons, fats and oils), (3) surfactants (anionic, cationic, amphoteric, nonionic, etc.), (4) moisturizers (glycerins, polyols such as glycols) (5) Organic UV absorbers (benzophenone derivatives, paraaminobenzoic acid derivatives, salicylic acid derivatives, etc.), (6) antioxidants (phenolic, organic acids or salts thereof, acid amides) System, phosphate system, etc.), (7) thickener, (8) fragrance, (9) colorant (pigment, pigment, dye, etc.), (10) physiologically active ingredients (vitamins, hormones, Mino acids), (11) an antibacterial agent or the like may be blended. The form of the cosmetic is not particularly limited, such as solid, liquid, or gel. In the case of liquid or gel, the dispersion may be any of a water-in-oil emulsion, an oil-in-water emulsion, and an oil type. The blending amount of zinc oxide in the cosmetic is preferably in the range of 0.1 to 50% by weight.

  The heat dissipating composition of the present invention contains the above zinc oxide as a heat conductive filler, and examples thereof include a resin composition, a grease composition, and a coating composition. Moreover, the sheet | seat, gel, elastomer, plastics, etc. which are formed using them may be sufficient. The compounding quantity of the said zinc oxide in the heat dissipation composition of this invention can be arbitrarily determined according to the performance of resin composition, such as the target heat conductivity and the hardness of a resin composition. In order to sufficiently exhibit the thermal conductivity of the zinc oxide, it is preferably 1% by volume or more, more preferably 5% by volume or more, still more preferably 10% by volume or more based on the total solid content in the resin composition. 30% by volume or more is most preferable. In this way, the thermal conductivity can be preferably 0.5 W / m · K or more, more preferably 1.0 W / m · K or more, and still more preferably 2.0 W / m · K or more. be able to. The heat dissipating composition of the present invention can be used as a material that efficiently attaches heat to an electronic device. The heat-radiating composition of the present invention can be used in combination with other components in addition to zinc oxide. For example, metal oxides such as magnesium oxide, titanium oxide, and aluminum oxide, aluminum nitride, and nitride Examples thereof include heat dissipating fillers other than zinc oxide such as boron, silicon carbide, silicon nitride, titanium nitride, metal silicon, and diamond, resins, and surfactants.

  The heat-dissipating resin composition can be used by mixing the above zinc oxide with a resin. The resin to be used may be a thermoplastic resin or a thermosetting resin, and an epoxy resin, a phenol resin, a polyphenylene sulfide (PPS) resin, a polyester resin, polyamide, polyimide, polystyrene, polyethylene, polypropylene, poly Vinyl chloride, polyvinylidene chloride, fluororesin, polymethyl methacrylate, ethylene / ethyl acrylate copolymer (EEA) resin, polycarbonate, polyurethane, polyacetal, polyphenylene ether, polyether imide, acrylonitrile-butadiene-styrene copolymer ( (ABS) resin, epoxy, phenol, liquid crystal resin (LCP), silicon resin, acrylic resin, and the like. In the case of a heat dissipating grease composition, it is mixed with a base oil containing mineral oil or synthetic oil. As the synthetic oil, α-olefin, diester, polyol ester, trimellitic acid ester, polyphenyl ether, alkylphenyl ether, silicone oil and the like can be used. Moreover, when setting it as a heat-radiating coating composition, resin may have sclerosis | hardenability or may not have curability. The paint may be a solvent-based one containing an organic solvent or a water-based one in which a resin is dissolved or dispersed in water.

  The heat dissipating composition of the present invention comprises (1) a thermoplastic resin and the zinc oxide kneaded in a molten state to obtain a resin composition for thermoforming. (2) a thermosetting resin and the zinc oxide. After kneading, it is heated and cured to obtain a resin composition. (3) The zinc oxide can be dispersed in a resin solution or dispersion to obtain a coating composition or a grease composition.

  Examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1
Zinc sulfate 0.3 mol and citric acid 0.3 mol were dissolved in 150 cc of pure water. Next, 500 cc of pure water is put into a 2 L four-necked flask, and the above-described aqueous zinc sulfate solution is added to the flask. 350 cc of an aqueous solution containing 0.5 mol of sodium hydroxide was added, the pH of the aqueous solution was adjusted to 12.5, and maintained for 30 minutes to precipitate a precipitate. Then, after heating up to 100 degreeC and ageing | curing | ripening for 1 hour, it cooled, filtered, washed with water, and dried, and obtained the zinc oxide powder (sample A) of this invention.
As a result of X-ray diffraction, this sample A was confirmed to be zinc oxide with good crystallinity. Also, from an electron micrograph (FIG. 1), a zinc oxide aggregate (size average of 1. mm) similar to a polyhedral sphere composed of hexagonal planes of zinc oxide particles having a hexagonal plate shape with a diameter of 0.25 μm. 5 μm).

Comparative Example 1
Zinc sulfate 0.3 mol and citric acid 0.3 mol were dissolved in 150 cc of pure water. Next, 500 cc of pure water is put into a 2 L four-necked flask, and the aqueous zinc sulfate solution is added to the flask, and the mixture is stirred at a rotation speed of 200 rpm using a two-blade stirrer having a blade diameter of 12 cm. A 350 cc aqueous solution containing 6 mol of sodium hydroxide was added, the pH of the aqueous solution was adjusted to 12.5, and maintained for 30 minutes to precipitate a precipitate. Then, after heating up to 100 degreeC and ageing | curing | ripening for 1 hour, it cooled, filtered, washed with water, and dried and obtained the zinc oxide powder (sample B).
As a result of X-ray diffraction, this sample B was confirmed to be zinc oxide with good crystallinity. Further, from the electron micrograph (FIG. 2), it was a zinc oxide aggregate (size: 3 μm) in which zinc oxide particles having a plate-like shape with a crossing diameter of 0.07 μm and a thickness of 0.3 μm were accumulated in the shape of a ball.

This sample A, an epoxy resin (bisphenol A type epoxy resin), and an amine curing agent were kneaded to produce a thermosetting thermally conductive resin composition (sample a).
The thermal conductivity of the sample a was calculated using a laser flash method. Using a thermal constant measuring device (model number TC7000) manufactured by ULVAC-RIKO, the thermal diffusivity was measured by a laser flash method according to JIS R1611, and using a heat flux differential scanning heat flow meter (model number DSC-50) manufactured by Shimadzu Corporation, JIS. The specific heat was measured according to K7123, the density was measured according to the JIS K7112A method by the underwater substitution method, and they were multiplied to calculate the thermal conductivity. As a result, the thermal conductivity of sample a is 0.9 W / m · K at a filling rate of 20 vol%, and 1.9 W / m · K at 40 vol%, which can be used as a heat-dissipating composition and a thermal conductive filler. I understood it.

  When the feeling when the sample A was directly rubbed on the skin was evaluated, it was found that the spread was good, and when blended in cosmetics, the dispersibility was good and the feeling of sliding on the skin was improved.

  The present invention is a zinc oxide aggregate formed of a plurality of zinc oxide particles having a columnar or plate-like particle shape, and can be used for various applications.

Claims (3)

A method of depositing zinc oxide by mixing a zinc compound, a carboxylic acid and / or salt thereof, and an alkali metal compound,
The amount of the carboxylic acid and / or salt thereof is 0.2 or more in terms of the molar ratio of the total amount of the carboxyl group (—COOH) and the salt thereof (—COOM) to the zinc atom of the zinc compound,
The amount L (mol / liter) of the alkali metal compound is such that the valence of the alkali metal compound is n and the valence of the zinc atom of the zinc compound is m. method for producing an acid zinc stack you characterized in that n is an amount corresponding to the following ranges. 2. The method for producing a zinc oxide aggregate according to claim 1 , wherein the amount L (mol / liter) of the alkali metal compound is in a range of 0.5 · mX / n to 0.9 · mX / n. To claim 1 or 2, characterized in that expressed in total molar ratio of the carboxyl group to zinc atoms of zinc compound (-COOH) and a salt thereof (-COOM) in the range of 1.0 to 5.0 The manufacturing method of the zinc oxide aggregate of description.

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