JP6231983B2 - Method for producing coated inorganic particles - Google Patents

Description

  The present invention relates to a method for producing coated inorganic particles.

  When the surface of the inorganic particles is coated with an organic compound, the dispersibility, storage stability and suitability for use of the inorganic particles are improved, and the function of the powder, such as adhesion to the skin (adhesion), feel (use feeling), Gloss, hiding power, coloring power, transparency, ultraviolet and infrared shielding ability, conductivity, fluorescence, luminescence, catalytic activity, hydrophobicity, hydrophilicity, etc. can be dramatically improved. For this reason, inorganic particles coated with organic compounds are widely used in various fields such as cosmetics, plastic additives, inks, paints, toners (magnetic powders, external additives), chemical fibers, packaging materials, and electronic materials. ing.

As a method for producing such organic compound-coated inorganic particles, for example, in Patent Document 1, a mixture of dimethicone (dimethylpolysiloxane) and dimethicone / methicone copolymer (methylhydrogensiloxane-dimethylsiloxane copolymer) is used as a powder. It is described that the mixture is coated on the surface of a powder by mixing with a mixer. Further, Patent Document 2 discloses that inorganic particle powder and a surface modifier are mixed in advance and then processed with an apparatus having a high-speed shearing action. As the surface modifier, those capable of hydrophobizing the particle surface of inorganic particles, specifically, organosilicon compounds such as fluoroalkylsilanes, alkoxysilanes, silane coupling agents and organopolysiloxanes are preferably used, and As an apparatus having a high-speed shearing action, for example, the use of a high-speed shearing mill, a blade-type kneader, a planetary mill or the like is described.
On the other hand, Patent Document 3 discloses a modified surface modifier in which a hydrogen atom of a Si—H bond in a molecular chain of methyl hydrogen polysiloxane is substituted with an alkoxy group. After adding water to the powder to be surface-modified as required, this modified surface modifier is added and stirred, and then dried to obtain a surface-modified powder. In addition, this modified surface modifier is produced by adding methylhydrogenpolysiloxane to a sodium hydroxide solution dissolved in methanol and allowing it to react.

JP 2007-56082 A JP 2008-143725 A JP 2009-138084 A

  In the methods of Patent Documents 1 and 2, it is necessary to perform strong pulverization on the powder in advance. And even if it grind | pulverizes, it is a powder state which the inorganic particle aggregated. For this reason, even if the silicone compound is coated, the coating tends to be non-uniform. On the other hand, in the method of Patent Document 3, since a modified surface modifier in which the hydrogen atom of the Si—H bond in the molecular chain of methyl hydrogen polysiloxane is previously substituted with an alkoxy group is used, There is little remaining, and hydrogen gas generation is little with it. However, reduction of the manufacturing cost and processing cost of a modified surface treating agent is required.

  Therefore, the present inventors can easily produce a more uniform coating by using an alkali-modified silicone compound in the method of coating a silicone compound on the surface of inorganic particles, Even if a silicone compound having a Si-H group such as dimethicone / methicone copolymer is used, the coating has less Si-H groups remaining in the coating due to alkali modification, and the generation amount of hydrogen gas can be reduced. In addition to the above, the present inventors have found that it is possible to coat with an inorganic compound and a fatty acid compound, thereby completing the present invention.

  That is, the present invention includes (1) a liquid containing a silicone compound added with alkali and inorganic particles (powder or slurry), and the surface of the inorganic particles is derived from the silicone compound added with alkali. (2) A liquid containing an alkali-added silicone compound, an inorganic compound, and inorganic particles (powder or slurry) are mixed, and the surface of the inorganic particles is obtained. A method for producing coated inorganic particles, including a step of coating with a silicone compound derived from an alkali-added silicone compound and an inorganic compound, (3) a liquid containing a silicone compound added with an alkali, a fatty acid compound, and inorganic particles (powder) Or a slurry) and the surface of the inorganic particles is mixed with a silicone compound derived from a silicone compound to which an alkali is added. (4) A liquid containing a silicone compound to which an alkali is added, a fatty acid compound, an inorganic compound, and inorganic particles (powder or slurry) are mixed. A method for producing coated inorganic particles, comprising a step of coating the surface of inorganic particles with a silicone compound derived from a silicone compound to which an alkali has been added, a fatty acid compound, and an inorganic compound, (5) inorganic particles (powder or slurry) And the inorganic compound are mixed, the surface of the inorganic particles is coated with the inorganic compound, and then the inorganic particles (powder or slurry) and the liquid containing the silicone compound to which alkali is added are mixed to form the inorganic particles. The coated inorganic particles are coated with a silicone compound derived from a silicone compound added with an inorganic compound and an alkali. (6) Inorganic particles (powder or slurry) and an inorganic compound are mixed and the surface of the inorganic particles is coated with an inorganic compound, and then the inorganic particles (powder or slurry) and a silicone compound to which an alkali is added A method for producing coated inorganic particles, which comprises mixing a liquid containing a fatty acid and a fatty acid compound and coating the surface of the inorganic particles with a silicone compound and a fatty acid compound derived from a silicone compound to which an inorganic compound and an alkali are added.

According to the method for producing coated inorganic particles of the present invention, a liquid containing an alkali-added silicone compound and inorganic particles can be mixed, and the surface of the inorganic particles can be easily treated with a silicone compound. A coating can be easily produced. Moreover, even if silicone compounds having Si-H groups such as methyl hydrogen polysiloxane and dimethicone / methicone copolymer are used, the remaining Si-H groups are reduced in the coating due to alkali modification, thereby reducing the amount of hydrogen gas generated. it can.
In addition, in the method for producing coated inorganic particles of the present invention, in addition to coating with a silicone compound, coating with an inorganic compound or coating with a fatty acid compound can be performed.
Moreover, in the method using the inorganic particle slurry of the present invention, after the inorganic particles are wet manufactured, the silicone compound coating, the inorganic compound coating, or the fatty acid compound coating can be performed without drying. For this reason, the processing cost can be further reduced by reducing the drying energy after wet manufacturing.
The coated inorganic particles thus produced are excellent in hydrophobicity (lipophilicity) since the coating of the silicone compound modified with alkali is excellent in uniformity. In addition, when a silicone compound having a Si—H group is used, the Si—H group is reduced by alkali and the generation of hydrogen gas is reduced accordingly.

The present invention is a method for producing coated inorganic particles, in which a silicone compound is coated on at least a part of the surface of the inorganic particles.
Various materials can be used as the inorganic particles. For example, mica, sericite, talc, clay, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, magnesium silicate, aluminum silicate, calcium phosphate, anhydrous silicic acid, alumina, magnesium oxide, zirconium oxide, hydroxide Examples thereof include aluminum, barium sulfate, magnesium aluminate silicate, magnesium aluminate metasilicate, boron nitride, zeolite, hydroxyapatite, and ceramic powder. Examples of the white pigment include basic lead carbonate, basic lead sulfate, titanium oxide, zinc oxide, cerium oxide, zinc phosphate, and aluminum phosphate. Color pigments include bengara, yellow iron oxide, black iron oxide, cobalt oxide, chromium oxide, chromium hydroxide, bitumen, ultramarine, carbon black, low-order titanium oxide, mango violet, cuprous oxide, graphite, yellow lead, cadmium Examples include yellow, cadmium red, cobalt blue, and molybdate orange. Examples of fluorescent pigments include zinc sulfide, zinc silicate, zinc cadmium sulfate, calcium sulfide, strontium sulfide, and calcium tungstate. Examples of pearl pigments include bismuth oxychloride, titanium mica, and fish scale foil. Examples of the fine particle powder include fine particle titanium oxide, fine particle zinc oxide, fine particle iron oxide, and fine particle cerium oxide. Examples of the metallic luster pigment include aluminum powder, zinc powder, gold powder, silver powder, tin powder, stainless steel powder, diamond powder, copper powder, nickel powder, and bronze powder. Examples of fluorescent pigments include zinc sulfide and calcium tungstate. Examples of other powders include tin oxide, ATO (antimony-doped tin oxide), ITO (tin-doped indium oxide), and Al-doped zinc oxide.
Among these, fine particle titanium oxide, fine particle zinc oxide, titanium dioxide, zinc oxide and the like are optimal. Fine particle titanium oxide and fine particle zinc oxide are used as an ultraviolet shielding agent, and titanium dioxide and zinc oxide are white pigments and various fillers. Used for.
Further, if necessary, a composite of these inorganic particles or a coating with an inorganic compound can be used. For example, fine particle powders such as fine particle titanium oxide, fine particle zinc oxide, fine particle iron oxide, fine particle cerium oxide are made of at least aluminum, calcium, magnesium, cerium, silicon, zirconium, titanium, zinc, iron, cobalt, manganese, nickel and tin. Examples thereof include a powder coated with one oxide or a hydrous oxide, a powder coated with an inorganic coloring pigment such as Bengala with silicic anhydride, and a powder coated with an extender pigment with a fine white pigment.

Such inorganic particles can be used in a powder state (including a wet state containing a certain amount of water) or in a slurry (suspension) state, but preferably used in a slurry state. .
When used in a powder state, it is preferably pulverized with an ordinary pulverizer. For example, a dry pulverizer or a crusher can be used. Examples of the dry pulverizer include a ball mill, a bead mill, a colloid mill, a conical mill, a disk mill, an edge mill, a milling mill, a hammer mill, a mortar, a pellet mill, a vertical axis impactor (VSI) mill, a wheelie mill, a roller mill, a jet mill, Examples thereof include a cross jet mill, a selenium mirror, a high pressure pulverizing roll, a Henschel mixer, a planetary mixer, and a nauta mixer. Examples of the crusher include a jaw crusher, a bucket crusher, a gyratory crusher, a cone crusher, a single roll crusher, a double roll crusher, and an impact crusher.
The size of the inorganic particles is preferably adjusted in the range of 0.01 to 10 μm, more preferably in the range of 0.01 to 4.0 μm, represented by the particle size D50.
In the present specification, the particle diameter D50 is a cumulative 50% particle diameter (median diameter), and is measured using a laser diffraction / scattering particle size distribution analyzer (LA-950, manufactured by Horiba, Ltd.).

When used in a slurry state, the solvent preferably contains water as the main component, and more preferably contains about 80% by mass or more of water. As other components other than water, alcohols such as ethanol, methanol and isopropanol, sodium hydroxide, potassium hydroxide, calcium hydroxide, hydrochloric acid, sulfuric acid and mixtures thereof may be included.
The pH of the inorganic particle slurry can be appropriately set by adding an alkali or an acid.
A known method can be used to prepare the inorganic particle slurry. For example, kneader kneading, hensil kneading, roll kneading, extruder kneading kneading mixer, propeller mixer, high speed mixer, dissolver, homogenizer, artemizer, wet jet mill, colloid mill, mass collider, bead mill, sand mill, ball mill, Inorganic particles can be dispersed in a solvent by using a wet mixing and dispersing machine such as a sand grinder, an in-line mill, or a medialess type high-speed stirring and dispersing machine.
The size of the inorganic particles in the slurry is preferably adjusted in the range of 0.01 to 4.0 μm, more preferably in the range of 0.01 to 0.2 μm, expressed by the particle size D50.

  As the inorganic particle slurry, it is preferable to use a slurry in which inorganic particles are produced in a wet state, or a slurry that is redispersed without being dried after the slurry is separated and washed as necessary. Specifically, inorganic particles such as fine particle titanium oxide, fine particle zinc oxide, fine particle iron oxide and fine particle cerium oxide are added to a solution of sulfate, nitrate, carbonate, chloride such as titanium, zinc, iron and cerium. A slurry prepared by decomposing or neutralizing each metal oxide, hydroxide or hydrated oxide is preferable. After the slurry is separated and washed as necessary, it is re-dispersed in a solvent without drying. More preferred is a slurry obtained.

  Next, the silicone compound coating treatment of inorganic particles (powder or slurry) will be described in detail.

Preparation of liquid containing silicone compound to which alkali is added In the method of the present invention, a liquid in which an alkali is previously added to the silicone compound is prepared.
When an alkali is added, the silicone compound is modified and the surface of the inorganic particles is easily coated. For example, when the silicone compound has a Si—H group, it becomes an Si—OH group or an Si—OA group (where A represents an alkali metal or an alkaline earth metal) due to alkali, and OH on the surface of the inorganic particles. The silicone compound is coated by reacting with the group.
Any alkali can be used, for example, alkali metal compounds such as sodium hydroxide, sodium carbonate, potassium hydroxide and potassium carbonate, alkaline earth metal compounds such as calcium hydroxide, ammonium hydroxide and ammonium carbonate. An ammonium compound such as can be used. The amount of alkali added may be such that the silicone compound can be modified, specifically 0.5 to 20% by mass, more preferably 0.5 to 5% by mass, and more preferably 0.5 to 5% by mass with respect to the silicone compound. 2% by mass is more preferable. The silicone compound may be in a solid state such as a colloid, and may be dissolved in a solvent as necessary. As the solvent, alcohols such as ethanol, methanol and isopropanol, organic solvents such as ethers, water solvents or mixed solvents thereof can be used, and organic solvents such as alcohols capable of dissolving silicone compounds are more preferable. After diluting the silicone compound with a solvent as necessary, an alkali is added with stirring to prepare a liquid containing the silicone compound to which the alkali has been added. The liquid temperature at the time of preparation can be appropriately set, and for example, a range of about 0 to 100 ° C. is appropriate.

The silicone compound is also called polysiloxane, and is an oligomer or polymer obtained by hydrolyzing silanes such as dichlorodimethylsilane and dehydrating and condensing the generated silanol. Specifically, for example, organopolysiloxanes such as dimethylpolysiloxane, dimethoxypolysiloxane, modified organopolysiloxane, organohydrogenpolysiloxanes such as methylhydrogenpolysiloxane, siloxanes such as methylhydrogensiloxane-dimethylsiloxane copolymer, etc. Examples thereof include oligomers or polymers obtained by dehydrating condensation of silanols such as copolymers, silicone polymers, and triorganosiloxysilicic acid. At least one selected from such silicone compounds can be used, and it is preferable to use a silicone compound having a Si—H group in the method of the present invention, particularly the methods (1) to (6), and a dimethicone / methicone copolymer. Is more preferable. Further, a silicone compound having an Si—H group and a silicone compound not having an Si—H group may be used in combination, or a silicone compound having no Si—H group and a dimethicone / methicone copolymer may be used in combination. .
Specifically, examples of the organopolysiloxane include dimethylpolysiloxane (also called dimethicone), and the basic chemical structure is represented by the following general formula (I). In general formula (I), n is preferably n = 1 to 400, and the kinematic viscosity is preferably about 1 to 1000 centistokes at 25 ° C.

Examples of the organohydrogenpolysiloxane include methylhydrogenpolysiloxane, and the polymerization degree n is more preferably an integer of 3 to 7.
Examples of the siloxane copolymer include a methylhydrogensiloxane-dimethylsiloxane copolymer (also referred to as a dimethicone / methicone copolymer), and its basic chemical structure is represented by the following general formula (II). In the present invention, In the general formula (II), m and n are m = 7 to 14, n = 3 to 8, and m + n = 10 to 22 are preferable.

(1) A liquid containing an alkali-added silicone compound and inorganic particles (powder or slurry) are mixed to coat the surface of the inorganic particles with the silicone compound.
In the method (1), a liquid containing a silicone compound to which the alkali is added is mixed with inorganic particles (powder or slurry), and the surface of the inorganic particles is coated with the silicone compound.
Mixing may be carried out by any method, but it is preferable to use a stirrer, a mixer, a pulverizer or the like. When inorganic particle powder is used, it is preferably mixed with the silicone compound liquid in a dry pulverizer or dry mixer, for example, ball mill, bead mill, colloid mill, conical mill, disk mill, edge mill, milling mill, hammer mill, mortar , Pellet mill, vertical axis impactor (VSI) mill, wheelie mill, roller mill, jet mill, cross jet mill, selenium mirror, high pressure grinding roll, Henschel mixer, super mixer, planetary mixer, nauta mixer and the like. The operating conditions etc. of a dry pulverizer etc. can be set up suitably. In order to mix the silicone compound liquid, it is preferable to add a small amount by using a sprayer, a sprayer, an atomizer or the like. When using an inorganic particle slurry, it is preferable to mix with a silicone compound liquid in a wet mixer or wet pulverizer, for example, a propeller mixer, a high speed mixer, a dissolver, a homogenizer, an artemizer, a wet jet mill, a colloid mill, a massco. Examples thereof include a Royder, a bead mill, a sand mill, a ball mill, a sand grinder, an in-line mill, and a medialess type high-speed stirring and dispersing machine. The operating conditions and the like of the wet pulverizer can be set as appropriate. In order to mix the silicone compound liquid, it is preferably added little by little from the nozzle. The mixing conditions can be appropriately set. For example, the mixing temperature is preferably room temperature, the mixing atmosphere is an oxygen gas, an oxidizing atmosphere such as air, an inert gas atmosphere such as nitrogen gas or argon gas, and a reducing property such as hydrogen gas. Any of gas atmosphere may be sufficient. Inert gas atmosphere is preferable for inorganic particles that are particularly susceptible to oxidation, such as silver and copper, and inorganic particles that are difficult to oxidize, such as titanium oxide and zinc oxide. Is economically preferable. The mixing time can be appropriately set, and for example, a range of about 0.1 to 10 hours is appropriate. Moreover, the slurry temperature of mixing can also be set suitably, for example, the range of about 0-100 degreeC is suitable. Any order of mixing may be used, and it is preferable to add and mix a liquid containing a silicone compound in which alkali is added to inorganic particles (powder or slurry). After mixing each liquid, you may adjust slurry pH suitably with an alkali or an acid. The coating amount of the silicone compound can be appropriately set. For example, the amount is preferably 1 to 50% by mass, more preferably 5 to 20% by mass, and still more preferably 5 to 15% by mass with respect to the inorganic particles.

(2) A liquid containing an alkali-added silicone compound, an inorganic compound, and inorganic particles (powder or slurry) are mixed to coat the surface of the inorganic particles with the silicone compound and the inorganic compound.
In the method (2), the surface of the inorganic particles is coated with an inorganic compound in addition to the silicone compound.
Examples of inorganic compounds include metal compounds or non-metallic compounds such as aluminum, calcium, magnesium, cerium, silicon, zirconium, titanium, zinc, iron, cobalt, manganese, nickel, tin, and at least one of such inorganic compounds. Seeds can be used. The inorganic compound is dissolved in a solvent as necessary. As the solvent, an aqueous solvent, an organic solvent, or a mixed solvent thereof can be used, and an aqueous solvent capable of dissolving an inorganic compound is preferably used. The inorganic compound may be added to the silicone compound solution.
By mixing an inorganic compound, a liquid containing the above-mentioned alkali-added silicone compound and inorganic particles (powder or slurry), the surface of the inorganic particles can be coated with the silicone compound and the inorganic compound.
Any order of mixing may be used. An inorganic compound may be added to inorganic particles (powder or slurry), and then a liquid containing a silicone compound to which an alkali is added may be added and mixed. As another order, A liquid containing an alkali-added silicone compound may be added to inorganic particles (powder or slurry), and then the inorganic compound may be added and mixed. Furthermore, you may mix the liquid mixture of the silicone compound and inorganic compound which added the alkali to the inorganic particle (powder or slurry), and may mix. Conditions such as the mixing method, mixing time, and mixing temperature can be the same as in the above (1), and after mixing the liquids, the slurry pH may be appropriately adjusted with an alkali or an acid. The inorganic compound coating may be in the form of the inorganic compound used, or an oxide, hydroxide, hydrated oxide or salt of the inorganic compound. The coating amount of the inorganic compound can be appropriately set. For example, 1 to 50% by mass is preferable with respect to the inorganic particles, 5 to 20% by mass is more preferable, and 5 to 15% by mass is still more preferable.

(3) A liquid containing an alkali-added silicone compound, a fatty acid compound, and inorganic particles (powder or slurry) are mixed to coat the surface of the inorganic particles with the silicone compound and the fatty acid compound.
In the method (3), the surface of the inorganic particles is coated with a fatty acid compound in addition to the silicone compound.
Examples of the fatty acid compounds include caprylic acid, capric acid, lauric acid, myristic acid, isomustic acid, palmitic acid, isopalmitic acid, stearic acid, isostearic acid, arachidic acid, undecylenic acid, oleic acid, myristoleic acid, elaidic acid Linoleic acid, linolenic acid, arachidonic acid, coconut oil fatty acid, beef tallow fatty acid, resin acid (abietic acid), salts thereof, metal salts thereof, and the like, and at least one of these fatty acid compounds is used. be able to. For example, the fatty acid constituting the N-acyl body is preferably a long-chain fatty acid, such as caprylic acid, capric acid, lauric acid, myristic acid, isomyristic acid, palmitic acid, isopalmitic acid, stearic acid, isostearic acid, arachidic acid. And undecylenic acid, oleic acid, myristoleic acid, elaidic acid, linoleic acid, linolenic acid, arachidonic acid, coconut oil fatty acid, beef tallow fatty acid, and resin acid (abietic acid). As salt forms, metal salts such as Na, K, Ba, Zn, Ca, Mg, Fe, Zr, Co, Al, Zr, Ti, ammonium salts, monoethanolamine, diethanolamine, triethanolamine, 2-amino Examples thereof include various alkanolamine salts such as 2-methyl-propanol, 2-amino-2-methyl-1,3-propanediol, and triisopropanolamine. Moreover, as dextrin fatty acid ester, it can select from the ester comprised from dextrin and a fatty acid, or its derivative (s). Preferably, for one dextrin molecule, an ester having at least a partial structure in which one molecule of a fatty acid having 8 to 24 carbon atoms is esterified to one of its hydroxyl groups, or a derivative thereof, such as 8 to 8 carbon atoms for one molecule of dextrin Examples include ester bodies having a structure in which one or a plurality of 24 fatty acids and one or more of the hydroxyl groups are ester-bonded, and derivatives in which the hydroxyl groups are further esterified with another fatty acid. .
The fatty acid compound is dissolved or emulsified in a solvent as necessary. As the solvent, an aqueous solvent, an organic solvent, or a mixed solvent thereof can be used, and an aqueous solvent is preferably used. The fatty acid compound may be added to the silicone compound solution.
A liquid containing a fatty acid compound, the above-described alkali-added silicone compound, and inorganic particles (powder or slurry) can be mixed to coat the surface of the inorganic particles with the silicone compound and the fatty acid compound. The order of mixing may be any, the fatty acid compound may be added to the inorganic particles (powder or slurry), and then the liquid containing the silicone compound to which the alkali has been added may be added and mixed. A solution containing an alkali-added silicone compound may be added to inorganic particles (powder or slurry), and then a fatty acid compound may be added and mixed. Furthermore, you may add and mix the liquid mixture of the silicone compound and fatty acid compound which added the alkali to the inorganic particle (powder or slurry). Conditions such as the mixing method, mixing time, and mixing temperature can be the same as in the above (1), and after mixing each solution, the slurry pH may be appropriately adjusted with an alkali or an acid. The coating amount of the fatty acid compound can be appropriately set. For example, 1 to 20% by mass is preferable, 1 to 10% by mass is more preferable, and 1 to 5% by mass is further preferable with respect to the inorganic particles.

(4) A liquid containing a silicone compound to which an alkali is added, a fatty acid compound, an inorganic compound, and inorganic particles (powder or slurry) are mixed, and the surface of the inorganic particles is coated with the silicone compound, the fatty acid compound, and the inorganic compound.
In the method (4), the surface of the inorganic particles is coated with a fatty acid compound and an inorganic compound in addition to the silicone compound. This method and the like can be performed according to the above (1), (2), and (3).

(5) Inorganic particles (powder or slurry) are mixed with an inorganic compound, the inorganic particles are coated with the inorganic compound, and then the inorganic particles (powder or slurry) and the silicone compound added with alkali are added. The liquid containing is mixed to coat the surface of the inorganic particles with the inorganic compound and the silicone compound.
In the method (5), after coating the surface of the inorganic particles with the inorganic compound, the silicone compound is coated. This method and the like can be performed according to the above (1) and (2).
First, inorganic particles (powder or slurry) and an inorganic compound are mixed, and if necessary, hydrolyzed or neutralized, and the surface of the inorganic particles is coated (first stage). Thereafter, the inorganic particles (powder or slurry) coated with the inorganic compound are separated, washed and redispersed as necessary to make a slurry, and then mixed with a liquid containing a silicone compound to which an alkali is added. The compound is coated (second stage).
The inorganic particles used in the first stage and the second stage may be in the same state or different in the powder or slurry, such as using the inorganic particle slurry in the first stage and using the inorganic particle powder in the second stage. Good.
The entire surface of the inorganic particles may be coated with an inorganic compound, and may be coated with a silicone compound via an inorganic compound, or a part of the particle surface may be coated with an inorganic compound and not via an inorganic compound. May be included.

(6) Inorganic particles (powder or slurry) and an inorganic compound are mixed, and the inorganic particles are coated on the surface of the inorganic particles, and then the inorganic particles (powder or slurry) and a silicone compound to which alkali is added A liquid containing a fatty acid and a fatty acid compound are mixed to coat the surface of the inorganic particles with the inorganic compound, the silicone compound, and the fatty acid compound.
In the method (6), after coating the surface of the inorganic particles with the inorganic compound, the silicone compound and the fatty acid compound are coated. This method etc. can be performed according to said (1)-(4).
First, inorganic particles (powder or slurry) and an inorganic compound are mixed, and if necessary, hydrolyzed or neutralized, and the surface of the inorganic particles is coated (first stage). After that, inorganic particles (powder or slurry) coated with this inorganic compound are separated, washed, redispersed and made into a slurry as necessary, and then mixed with a liquid containing an alkali-added silicone compound and a fatty acid compound. Then, the silicone compound and the fatty acid compound are coated (second stage).
The inorganic particles used in the first stage and the second stage may be in the same state or different in the powder or slurry, such as using the inorganic particle slurry in the first stage and using the inorganic particle powder in the second stage. Good.
The entire surface of the inorganic particles may be coated with an inorganic compound, and may be coated with a silicone compound via an inorganic compound, or a part of the particle surface may be coated with an inorganic compound and not via an inorganic compound. May be included.

  In addition to the silicone compounds and fatty acid compounds described in the methods (1) to (6), organic silicon compounds such as alkoxysilanes, alkylsilanes, and trimethylsiloxysilicic acid, and organics such as polyolefins, hydrogenated lecithins, and N-acylamino acids. The compound may be coated. Examples of the alkoxysilane include methyltrimethoxysilane, ethyltriethoxysilane, octyltriethoxysilane, and the like. Examples of the alkyl silane include methyl silane, ethyl silane, octyl silane and the like. Further, trimethylsiloxysilicic acid is obtained by dissolving water glass sodium obtained by substituting sodium with a trimethylsilyl group in a solvent. In addition, polyethylene, polypropylene, and the like can be used as the polyolefin. For example, low molecular polyethylene having a molecular weight of 500 to 20000 and a melting point of 40 ° C. or more, polyethylene oxide obtained by oxidizing polypropylene, maleated polyethylene, polypropylene oxide, and the like. Commercial products can be used. The hydrogenated lecithin is a hydrogenated natural lecithin extracted from egg yolk, soybean, corn, rapeseed or the like, and hydrogenated lecithin having an iodine value of preferably 30 or less, more preferably 15 or less. It is a glyceride having a phosphate group. As the salt form, a water-insoluble hydrogenated lecithin metal salt such as Al, Mg, Ca, Zn, Zr and Ti is preferable. N-acylamino acids are those in which the amino group and / or imino group of the amino acid is acylated. Examples of amino acid types include glycine, alanine, β-alanine, valine, leucine, isoleucine, phenylalanine, proline, threonine, serine, arginine, histidine, lysine, aspartic acid, glutamic acid, tyrosine, methionine, cystine, cysteine, etc. Can do.

  The dry powder or wet powder obtained by the coating treatment in the above (1) to (6) may be pulverized using a dry pulverizer or a dry mixer as necessary to obtain a dry pulverized powder. As the dry pulverizer or the like, the above-mentioned pulverizer and mixer can be used, and an airflow pulverizer is preferable. An airflow pulverizer is a machine that jets argon gas, nitrogen gas, or the like from a nozzle at high speed, and accelerates powder particles by this gas flow and collides with each other to pulverize them, using a jet mill, a cross jet mill, a selenium mirror, etc. be able to. Moreover, it is preferable to grind | pulverize with mixers, such as a hensil mixer and a super mixer, mills, such as a ball mill and a sand grinder. The pulverization conditions can be set as appropriate. For example, the pulverization temperature is preferably room temperature, the mixed atmosphere is an oxygen gas, an oxidizing atmosphere such as air, an inert gas atmosphere such as nitrogen gas or argon gas, and a reducing property such as hydrogen gas. Any of gas atmosphere may be sufficient. Inert gas atmosphere is preferable for inorganic particles that are particularly susceptible to oxidation, such as silver and copper, and inorganic particles that are difficult to oxidize, such as titanium oxide and zinc oxide. Is economically preferable.

  The dried powder or wet powder or the dry pulverized powder after the coating treatment in the above (1) to (6) may be dried or fired as necessary. On the other hand, the inorganic particle slurry after the coating treatment in the above (1) to (6) may be separated or washed as necessary, and then dried or fired. The drying temperature is in the range of about 50 to 200 ° C., and the firing temperature is preferably in the range of about 200 to 500 ° C. The drying and firing atmosphere is an atmosphere containing oxygen, an oxygen-containing atmosphere such as oxygen gas, or an inert gas atmosphere such as nitrogen gas. Can be done. The dried or fired coated inorganic particles may be pulverized using a dry pulverizer, a dry mixer, or the like according to the intended use. As the dry pulverizer, the above-mentioned pulverizer and mixer can be used, and airflow pulverizers such as a jet mill, a cross jet mill, and a selenium mirror are preferable. Moreover, it is preferable to grind | pulverize with mixers, such as a hensil mixer and a super mixer, mills, such as a ball mill and a sand grinder. The pulverization conditions can be set as appropriate. For example, the pulverization temperature is preferably room temperature, the mixed atmosphere is an oxygen gas, an oxidizing atmosphere such as air, an inert gas atmosphere such as nitrogen gas or argon gas, and a reducing property such as hydrogen gas. Any of gas atmosphere may be sufficient. Inert gas atmosphere is preferable for inorganic particles that are particularly susceptible to oxidation, such as silver and copper, and inorganic particles that are difficult to oxidize, such as titanium oxide and zinc oxide. Is economically preferable.

Next, the coated inorganic particles of the present invention may be dispersed in a dispersion medium as necessary to form a dispersion. Although the density | concentration of a coating inorganic particle can be adjusted suitably, a higher density | concentration is preferable. Specifically, 10-75 mass% is preferable, 10-65 mass% is more preferable, and 30-60 mass% is still more preferable. The dispersion medium is not particularly limited, and various types can be used as appropriate, and a lipophilic dispersion medium can be suitably used.
Specifically, monohydric alcohol solvents such as ethanol, propyl alcohol, isopropyl alcohol, butanol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, phenol and benzyl alcohol, normal Petroleum hydrocarbons such as pentane, normal hexane, normal heptane, normal octane, isohexane, isooctane, gasoline, mineral spirits, aromatic hydrocarbon solvents such as benzene, toluene, xylene, cyclohexane, ethylbenzene, amylbenzene, dipentene , Plant hydrocarbon solvents such as turpentine oil, nitro hydrocarbon solvents such as nitroparaffin and nitrobenzene, acetone, methyl ethyl ketone, Ketone solvents such as til isobutyl ketone, ethyl butyl ketone, diisobutyl ketone, halogenated hydrocarbon solvents such as methylene chloride, chloroform, carbon tetrachloride, perchlorethylene, monochlorobenzene, ethyl ether, isopropyl ether, butyl ether, Ether solvents such as hexyl ether, propylene oxide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, methyl formate, ethyl formate, butyl formate, methyl acetate, ethyl acetate, butyl acetate, acetic acid Ester solvents such as amyl, ethyl propionate, butyl propionate, isobutyl propionate, ethyl butyrate, butyl butyrate, methyl lactate, ethyl lactate, butyl lactate, amyl lactate, safra -Oil, soybean oil, evening primrose oil, grape seed oil, rosehip oil, cucumber nut oil, almond oil, sesame oil, wheat germ oil, corn oil, cottonseed oil, avocado oil, olive oil, camellia oil, persic oil, castor oil, peanut oil Oils such as hazelnut oil, macadamia nut oil, medofoam oil, cocoa butter, shea butter, tree wax, coconut oil, palm oil, palm kernel oil, beef tallow, horse fat, mink oil, milk fat, egg yolk oil, turtle oil, Liquid paraffin, liquid isoparaffin, squalane, squalene, petrolatum, paraffin, ceresin, microcrystalline wax and other hydrocarbon oils, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, undecylenic acid, Fatty acids such as hydroxystearic acid and lanolin fatty acid, milli Still alcohol, cetyl alcohol, cetostearyl alcohol, stearyl alcohol, aralkyl alcohol, behenyl alcohol, oleyl alcohol, jojoba alcohol, batyl alcohol, higher alcohols such as cholesterol, phytosterol, lanolin alcohol, isostearyl alcohol, isopropyl isostearate, ethyl oleate , Isopropyl myristate, isoisopropyl palmitate, cetyl octanoate, diisostearyl malate, glyceryl tricaprylate, isooctyl isononanoate, isononyl isononanoate, isotridecyl isononanoate, octyldodecyl neopentanoate, isotridecyl neopentanoate, myristyl neopentanoate, diisononane Propylene glycol acid, tri-2- Ester oils such as glyceryl tilhexanoate, trimethylolpropane tri-2-ethylhexanoate, beeswax, candelilla wax, whale wax, cotton wax, carnauba wax, bayberry wax, nukarou, ibotarou, orange luffy oil, montan wax, sugarcane wax, shellac wax, lanolin , Jojoba oil, waxes, methylpolysiloxane, methylphenylpolysiloxane, decamethylcyclotetrasiloxane, alkyl-modified silicone, alcohol-modified silicone, amino-modified silicone, epoxy-modified silicone, olefin-modified silicone, carboxyl-modified silicone, carbinol Modified silicone, phenol modified silicone, methacryl modified silicone, mercapto modified silicone, phosphoric acid modified silicone, fluorine modified silicone Silicones such as corn, higher fatty acid-modified silicone, polyether-modified silicone, perfluoropolyether, hydrofluoroether, perfluoromethylcyclopentane, perfluorodimethylcyclohexane, perfluorodimethylcyclobutane, methoxynonafluorobutane, ethoxynonafluorobutane Fluorine oils such as dodecafluoropentane, tetradecafluorohexane, perfluorodecane, perfluorooctane, 4-trifluoromethylperfluoromorpholine, 4-pentafluoroethylperfluoromorpholine, paraaminobenzoic acid, paraamino as UV absorber Benzoic acid monoglycerin ester, N, N-dimethylparaaminobenzoic acid ethyl ester, N, N-diethoxyparaaminobenzoic acid ethyl Benzoic acids such as ethyl ester, N, N-dipropoxyparaaminobenzoic acid ethyl ester, anthranilic acids such as homomenthyl-N-acetylanthranilate, amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, etc. Salicylic acids, octylcinnamate, ethyl-4-isopropylcinnamate, methyl-2,5-diisopropylcinnamate, ethyl-2,4-diisopropylcinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinna Mate, isoamyl-p-methoxycinnamate, octyl-p-methoxycinnamate, 2-ethoxyethyl-p-methoxycinnamate, cyclohexyl-p-methoxycinnamate Cinnamic acids such as namate, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4 -Benzophenones such as phenylbenzophenone and 4-hydroxy-3-carboxybenzophenone, 3-benzylidene-d, l-camphor, urocanic acid, urocanic acid ethyl ester, 2-phenyl-5-methylbenzoxazole, dibenzalazine, dianisoyl Examples thereof include methane, 4-tert-butyl-4′-methoxydibenzoylmethane, a silicone-modified ultraviolet absorber, a fluorine-modified ultraviolet absorber. Of these, one or more can be used as the lipophilic solvent in the present invention.

In addition, pigment dispersions, oils, surfactants, ultraviolet absorbers, preservatives, antioxidants, film forming agents, humectants, thickeners, dyes, pigments, fragrances and the like are appropriately added to the dispersion of the present invention. Can be blended.
For example, alkyl ether sulfates such as POE lauryl sulfate triethanolamine, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, higher alkyl sulfates such as sodium lauryl sulfate and potassium lauryl sulfate, N-acyl sarcosine acid, N- Higher fatty acid amide sulfonates such as sodium myristoyl-N-methyltaurine, higher fatty acid ester sulfates such as hydrogenated coconut oil fatty acid sodium glycerol sulfate, higher fatty acid ester sulfonates, higher fatty acid alkylolamide sulfates, fatty acid soaps , Sulfosuccinate, secondary alcohol sulfate, POE alkyl ether carboxylic acid, POE alkyl allyl ether carboxylate, α-olefin sulfonate, lauroyl mono Anionic surfactants such as sodium tanolamide succinate, diethanolamine N-palmitoyl aspartate, sodium caseinate, alkyltrimethylammonium salts such as stearyltrimethylammonium chloride, alkyls such as distearyldimethylammonium chloride and dialkyldimethylammonium chloride Quaternary ammonium salts, alkyl pyridinium salts, alkyl amine salts, alkyl dimethyl benzyl ammonium salts, alkyl isoquinolinium salts, dialkyl morpholinium salts, POE alkyl amines, polyamine fatty acid derivatives, amyl alcohol fatty acid derivatives, benzalkonium chloride , Cationic surfactants such as benzethonium chloride, 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy Imidazoline-based amphoteric surfactants such as disodium salt, betaine-based amphoteric surfactants such as alkylbetaine, amidebetaine, and lauryldimethylaminoacetic acid betaine, glycerin fatty acid esters such as glyceryl sesquioleate and glyceryl monostearate, polyricinoleic acid Polyglycerin fatty acid esters such as hexaglyceryl, diglyceryl monostearate, decaglyceryl decaoleate, sorbitan fatty acid esters such as sorbitan monooleate and sorbitan sesquioleate, propylene glycol fatty acid esters such as propylene glycol monostearate, POE sorbitan monooleate POE sorbitan fatty acid ester such as POE glycerin fatty acid ester such as POE glycerin triisostearate, POE monooleate POE fatty acid esters such as POE distearate, POE alkyl ethers such as POE lauryl ether and POE stearyl ether, POE POP alkyl ethers such as POE / POP hydrogenated lanolin, hydrogenated castor oil derivatives, glycerin alkyl ethers, alkanolamides, sucrose fatty acid esters , Dextrin fatty acid esters, starch fatty acid esters, nonionic surfactants such as hydroxystearic acid, phospholipids such as lecithin, glycolipids such as trehalose lipid, perfluoroalkyl phosphate, perfluoroalkyl sulfonate, Fluorine surfactants such as perfluoroalkyl carboxylates, alkyl methacrylate methacrylate copolymers, natural or synthetic clay minerals such as bentonite, smectite, kaolin, etc. Organically-modified clay minerals such as amine cation-modified bentonite, can be exemplified aerosol or the like.

  The method for kneading or mixing and dispersing the coated inorganic particles in the dispersion medium is not particularly limited as long as a known method is adopted. For example, kneader kneading, kneading kneading, roll kneading, extruder kneading kneading mixer, propeller mixer, high speed mixer, dissolver, homogenizer, artemizer, wet jet mill, colloid mill, mass colloider, bead mill, sand mill, ball mill, A dispersion can be produced using a wet grinder / wet grinder such as a sand grinder, an in-line mill, or a medialess type high-speed agitator / disperser.

  Further, the coated inorganic particles of the present invention may be blended to make a cosmetic, or the dispersion may be used to make a liquid cosmetic. For example, powder foundation, liquid foundation, oil foundation, stick foundation, pressed powder, face powder, lipstick, lip gloss, blusher, eye shadow, eyebrow, eyeliner, mascara, aqueous nail enamel, oily nail enamel, emulsified nail enamel, Finishing cosmetics such as enamel top coat, enamel base coat, emollient cream, cold cream, whitening cream, milky lotion, lotion, essence, carmine lotion, liquid facial cleanser, facial cleansing foam, facial cleansing cream, facial cleansing powder, makeup cleansing, body gloss Cosmetics for skin such as hair gloss, hair cream, hair shampoo, hair rinse, hair color, hair brushing agent, etc. Only stop or sunburn cream or milk, can be given soap, bath agent, perfume and the like.

  The blending amount of the coated inorganic particles can be appropriately blended according to the form of the cosmetic. For example, the liquid cosmetic is preferably 1 to 20% by mass, more preferably 1 to 15% by mass, and more preferably 1 to 10%. More preferred is mass%. As cosmetics, those usually blended can be used, for example, pigment dispersants, oils, surfactants, ultraviolet absorbers, preservatives, antioxidants, film forming agents, moisturizers, thickeners, Dyes, pigments, fragrances and the like can be appropriately blended.

  The coated inorganic particles of the present invention can be suitably used for applications other than dispersions and cosmetics, such as plastic additives, inks, paints, toners (magnetic powders, external additives), chemical fibers, packaging materials, Widely used in various fields such as electronic materials.

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

Example 1
The aqueous titanium tetrachloride solution was hydrolyzed to obtain fine particle titanium oxide. This aqueous titanium oxide slurry was filtered, washed, and redispersed to prepare an aqueous titanium oxide slurry.
The slurry contained 90% by mass of water, and the size of the inorganic particles in the slurry was in the range of 0.3 to 1.5 μm in terms of the particle size D50.
A sodium aluminate aqueous solution was added to the titanium oxide aqueous slurry, the pH was adjusted to 6.5, and a coating treatment of 23% by mass of aluminum hydroxide was performed on the titanium oxide.
On the other hand, 0.05 ml / g of 20% aqueous sodium hydroxide solution was added to a solution obtained by diluting dimethicone / methicone copolymer in ethanol 4 times its mass in advance, and stirred for 15 minutes to partially hydrolyze the dimethicone / methicone copolymer. Disassembled. Sodium hydroxide added to the dimethicone / methicone copolymer was 1% by weight. This was used as an alkali-added silicone compound solution.
The alkali-added silicone compound liquid is added to the aluminum hydroxide-coated titanium oxide aqueous slurry (15% by mass with respect to titanium oxide in terms of TiO ₂ ), and the mixture is stirred with a homogenizer at 70 ° C. for 2 hours. Mixed. The obtained slurry was filtered and washed to obtain a fine titanium oxide cake coated with aluminum hydroxide and a silicone compound. Next, the cake was heated and dried at 150 ° C. for 4 hours with a dryer, and then subjected to finish pulverization with an airflow pulverizer (jet mill) to obtain coated inorganic particles (sample A) of the present invention.

Example 2
In Example 1, instead of adding 15% by mass of the alkali-added silicone compound liquid with respect to titanium oxide, 10% by mass of the alkali-added silicone compound liquid with respect to titanium oxide and 5% by mass of stearin with respect to titanium oxide. The coated inorganic particles (Sample B) of the present invention were obtained in the same manner as in Example 1 except that sodium oxide was added to obtain a fine titanium oxide cake coated with aluminum hydroxide, a silicone compound and stearic acid. It was.

Example 3
In Example 1, instead of adding 0.05 ml / g of a 20% aqueous sodium hydroxide solution to a solution obtained by diluting dimethicone / methicone copolymer in ethanol four times in advance, 1 ml / g was added to add an alkali-added silicone compound solution. Except that, the coated inorganic particles (Sample C) of the present invention were obtained in the same manner as in Example 1. Sodium hydroxide added to the dimethicone / methicone copolymer was 20% by weight.

Example 4
In Example 1, 0.05% / g of 20% aqueous sodium hydroxide solution was added to a solution obtained by diluting dimethicone / methicone copolymer in 4 volumes of ethanol in advance, and instead of stirring for 15 minutes, 2% aqueous sodium hydroxide solution was changed to 0%. The coated inorganic particles (Sample D) of the present invention were obtained in the same manner as in Example 1 except that 0.05 ml / g was added and stirred for 1 minute to obtain an alkali-added silicone compound solution. Sodium hydroxide added to the dimethicone / methicone copolymer was 0.1% by weight.

Example 5
The aluminum hydroxide-coated titanium oxide aqueous slurry of Example 1 was dried, and was pulverized in advance with an airflow pulverizer (jet mill). A predetermined amount was charged into a Henschel mixer, and the alkali-added silicone compound liquid of Example 1 was added to water. 6% by mass with respect to the mass of the aluminum oxide-coated titanium oxide was added by spraying, stirred and mixed, and then pulverized again with an airflow pulverizer (jet mill). The pulverized powder was heat-treated at 140 ° C. for 30 minutes with a dryer to obtain coated inorganic particles (Sample E).

Example 6
In Example 5, the treatment was carried out in the same manner as in Example 5 except that the aluminum hydroxide-coated titanium oxide aqueous slurry was dried and pulverized in advance with a hammer mill instead of pulverizing with an airflow pulverizer. Particles (Sample F) were obtained.

Example 7
In Example 5, treatment was performed in the same manner as in Example 5 except that droplets were added instead of spraying to obtain coated inorganic particles (sample G).

Example 8
In Example 5, treatment was performed in the same manner as in Example 5 except that pulverization after spraying was performed again with a hammer mill, to obtain coated inorganic particles (sample H).

Example 9
The alkali-added silicone compound liquid of Example 1 (6% by mass with respect to titanium oxide) was added to the aluminum hydroxide-coated titanium oxide aqueous slurry of Example 1, and the mixture was stirred at room temperature for 30 minutes. And wet pulverized until a predetermined particle size was obtained. The obtained slurry was washed by filtration to obtain a fine titanium oxide cake coated with aluminum hydroxide and a silicone compound. Next, this cake was heated and dried at 90 ° C. for 4 hours in a dryer, further subjected to heat treatment at 140 ° C. for 30 minutes, and finished and pulverized with an airflow pulverizer (jet mill), and coated inorganic particles (Sample I) Got.

Comparative Example 1
In Example 1, instead of adding an alkali-added silicone compound solution of 15% by mass with respect to titanium oxide, a silicone compound solution obtained by diluting a dimethicone / methicone copolymer in 4 times the amount of ethanol (without adding sodium hydroxide) was used. Except for the addition, coated inorganic particles (Sample J) were obtained in the same manner as in Example 1.

Comparative Example 2
The fine particle titanium oxide treated with aluminum hydroxide in Example 1 was filtered, washed and dried, and then pulverized using a hammer mill. 7.5% by weight of dimethicone / methicone copolymer was added to this powder, mixed with stirring using a Henschel mixer, heat-treated at 150 ° C. for 20 minutes, and then subjected to finish grinding with an airflow crusher (jet mill). Thus, coated inorganic particles (sample K) were obtained.

Evaluation method (Evaluation of hydrogen generation)
In a 50 ml Erlenmeyer flask, 4 g of each sample obtained in Examples 1 to 9 and Comparative Examples 1 and 2 and 40 ml of ethanol were added and stirred. In a closed system, 5 ml of 10% aqueous sodium hydroxide solution was added dropwise to generate hydrogen gas, and the amount of gas generated was measured by cylinder collection.

* Hydrogen generation amount (ml / g) = (total gas generation amount when adding 10% sodium hydroxide (ml) −gas generation amount when adding ethanol (ml)) / sample mass (g)

(Hydrophobic evaluation)
The following water / methanol method was used for evaluation.
(1) Each sample was floated on an aqueous solution variously changed in a mass ratio of methanol / water in the range of 0/100 to 100/0, shaken lightly, and then allowed to stand.
(2) The maximum blending amount of methanol with which the sample can maintain hydrophobicity with respect to the aqueous solution was defined as the degree of hydrophobicity.

  The evaluation results are shown in Table 1. In Examples 1 to 9, since a dimethicone / methicone copolymer with sodium hydroxide added was used, the amount of hydrogen gas generated could be suppressed as compared with Comparative Example 2. On the other hand, since the degree of hydrophobicity was higher than that of Comparative Example 1, it was found that the silicone compound was more uniformly coated.

  The present invention is a method for producing silicone compound-coated inorganic particles, and according to the present invention, coated inorganic particles having excellent long-term oil dispersion stability, hydrophobic stability, etc. can be produced at a low cost by a simple method. it can. Such coated inorganic particles are widely used in various fields such as cosmetics, plastic additives, inks, paints, toners (magnetic powder, external additives), chemical fibers, packaging materials, and electronic materials.

Claims (5)

Inorganic particle slurry and inorganic compound are mixed to hydrolyze or neutralize the inorganic compound, and the surface of the inorganic particle is coated with the inorganic compound, and then the inorganic particle coated with the inorganic compound is pulverized with a dry pulverizer After alkali modification of the silicone compound by adding an alkali to the silicone compound comprising dimethicone / methicone copolymer dissolved in an organic solvent at a ratio of 0.5 to 20% by mass with respect to the silicone compound Then, the liquid containing the alkali-modified silicone compound is mixed with a dry pulverizer or a dry mixer to coat the surface of the inorganic particles with the alkali-modified silicone compound via the inorganic compound, A method for producing coated inorganic particles, which is pulverized by a dry pulverizer . The inorganic particle slurry and the inorganic compound are mixed to hydrolyze or neutralize the inorganic compound, and the surface of the inorganic particles is coated with the inorganic compound, and then the inorganic particles coated with the inorganic compound are pulverized with a dry pulverizer. After alkali modification of the silicone compound by adding an alkali to the silicone compound comprising dimethicone / methicone copolymer dissolved in an organic solvent at a ratio of 0.5 to 20% by mass with respect to the silicone compound The alkali-modified silicone compound-containing liquid and the fatty acid compound are mixed with a dry pulverizer or a dry mixer, and the alkali-modified silicone compound and the fatty acid compound are covered with the inorganic compound, Next, a method for producing coated inorganic particles, which is pulverized by a dry pulverizer . The method for producing coated inorganic particles according to claim 1 or 2, wherein the particle size D50 of the inorganic particle powder is in the range of 0.01 to 10 µm. The method for producing coated inorganic particles according to any one of claims 1 to 3, wherein the surface of the inorganic particles is coated with the alkali-modified silicone compound and then pulverized with an airflow pulverizer . The method for producing coated inorganic particles according to claim 4, wherein the coated inorganic particles are dried after being pulverized by an airflow pulverizer .