JP6084384B2 - Powder surface treatment method, surface treated powder and cosmetic - Google Patents

Description

  The present invention relates to a powder surface treatment method, a surface-treated powder treated by the method, and a cosmetic containing the surface-treated powder.

  Surface treatment of powders used in cosmetics, such as silicone treatment and fluorine treatment, is roughly performed for two reasons. One is to solve the problems of powder, such as improved dispersibility in water and oil, and suppression of surface activity, and the other is a new feeling of use and water repellency that the powder did not have. It is to give new functions such as.

  In general, powders used in cosmetics are mainly metal oxides and composite powders thereof, and the surface has surface functional groups such as hydroxyl groups, and the surface state depends on the type of powder and the amount of adsorbed water. Is different. For this reason, when surface treatment is performed by reacting with a surface treatment agent using bonding or adsorption to a surface functional group, the same surface treatment agent or the same surface treatment can be used if the type and surface state of the powder to be treated are different. Even if the method is used, it is not always possible to perform a surface treatment that can bring out a similar function.

  Also, depending on the particle surface shape and particle size, the desired effect is often not obtained unless the amount of the surface treatment agent and the surface treatment method are optimized.

  Therefore, in order to solve these problems in the surface treatment, in Patent Document 1, as a pretreatment, the surface of the inorganic powder base is activated by heating, plasma, hydrothermal reaction, etc., and the water and oil repellent is made reactive. The method of processing with an auxiliary agent is performed. However, these pretreatments for activation are severe in conditions such as processing temperature and pressure, and have low versatility. Furthermore, in plasma, an example using a plasma spray device is shown, but since the plasma spray device is mainly intended for plate-shaped devices and is a device that irradiates plasma in the gas phase, it is activated. The degree of was affected by the aggregation state and shape of the powder, and the water and oil repellency properties were also poor. Furthermore, the plasma apparatus itself was large and lacked versatility.

  Patent Documents 2 and 3 introduce a grinding method and an acid / alkali etching method as activation methods. However, as described in Patent Document 3, it is difficult to scale up by a method other than grinding, and since it is not a highly homogeneous method that produces a uniform active surface with respect to particles, the surface treatment is performed. It was difficult to bring out sufficient performance.

  On the other hand, some use metal salts in the surface treatment process. For example, in Patent Document 4, in order to completely align and adsorb hydrogenated lecithin, soluble metal salts such as Al, Mg, Ca, Zn, and Ti are used to completely powder hydrogenated lecithin as a surface treatment agent. It is deposited and adsorbed on the body surface. Patent Document 5 shows a method of pretreating a flaky substrate with a hydroxide or hydrate of aluminum or silicon when a hydrophobic coupling agent is used as a surface treatment agent. Further, Patent Document 6 discloses that a clay mineral is pretreated with a metal hydroxide or a hydrate of a metal salt and then fluorinated. However, when powders that have been pretreated with these metal salts and then surface treated with a surface treatment agent are added to cosmetics, deterioration of other components due to elution of metal salts in the cosmetics, precipitation of lysates, etc. , Stability over time may be deteriorated. For this reason, in cosmetics, it is preferable that there are few additives other than a surface treating agent.

  For uniform surface treatment, it is important to disperse the agglomerated powder uniformly in the gas phase or in the liquid phase before reacting with the surface treatment agent in advance. However, in recent years, many powders for cosmetics have been made fine particles, and it is becoming difficult to uniformly disintegrate and disperse them by mechanical force alone. In addition, when a dispersant such as a surfactant is added, an effect contrary to the desired surface treatment effect is often brought about.

JP-A-1-197420 JP 2-127477 JP-A-3-9964 JP-A-60-190705 JP 2002-194247 A JP 2003-81733 A

  In surface treatment of powders used in cosmetics and the like, it is possible to easily obtain surface treatment effects such as improved dispersibility and water and oil repellency while suppressing as few additives and dispersants as possible. Development of a new surface treatment method that can be performed has been desired.

  The problem to be solved by the present invention is a surface treatment method for extracting an excellent surface treatment effect by applying a surface treatment to the powder surface without using an additive or a dispersant or suppressing the amount of use, and It is to provide a powder surface-treated by the method and a cosmetic containing the surface-treated powder.

  As a result of intensive studies on the above problems, the present inventor has found that a surface treatment can be performed satisfactorily by irradiating the powder in water with plasma as a pretreatment for the surface treatment of the powder. Was completed. That is, in the present invention, the electrode configuration for generating plasma is such that one of the pair of electrodes is placed in water or in contact with the water surface, and the other electrode is disposed in the air above the water surface. Then, a high voltage is applied between both electrodes to generate plasma and perform pretreatment. In this plasma pretreatment, the powder is in water and the powder surface is covered with water.

In the present invention, after the plasma pretreatment, the obtained powder aqueous dispersion, or the powder taken out from the aqueous dispersion by any method, is subjected to metal soap, perfluoroalkylethyl phosphate ester. Diethanolamine salt, fluoroalkyl acrylate / polyalkylene glycol acrylate polymer, perfluoropolyether phosphate, anionic or cationic polymer having perfluoropolyether chain, hydrogenated lecithin, acylated amino acid, α-tocopherol phosphate ester salt , a surface treatment for coating the silicone oil, the surface treatment agent of the silane compound.

  In the present invention, “water” and “water” in the “water surface” all refer to an aqueous dispersion medium in which fine particles are dispersed and include an aqueous solution.

  As a method of generating plasma in the present invention, one of the pair of electrodes is placed in water or in contact with the water surface, and the other electrode is placed in the air above the water surface. In this method, an electrode is formed, and a high voltage is applied between both electrodes to generate plasma. That is, as shown in the dispersion apparatus of the present invention in FIG. 1, one electrode is in a state immersed in water or in contact with the water surface, and the other is disposed in the air above the water surface at an appropriate distance from the water surface. Are in a positional relationship. Thereby, plasma is generated between the electrode on the upper surface of the water surface and the water surface, and acts directly near the water surface.

  In the electrode on the upper surface of the water in the present invention, the shape may be a needle shape, a hollow needle shape, a linear shape, a flat plate shape, or the like, but is not particularly limited. Among them, a needle-shaped one that generates a non-uniform electric field and lowers a dielectric breakdown voltage and easily generates plasma even at a low voltage is preferable. Examples of the material of the electrode include copper, copper tungsten, graphite, tungsten, titanium, stainless steel, molybdenum, aluminum, iron, and the like, and are not particularly limited. In consideration of electrode consumption, tungsten or titanium is preferable.

  Further, the shape and material of the other electrode immersed in water or brought into contact with the water surface are not particularly limited as long as the other electrode does not act on the liquid or the like.

  As a power source used for generating plasma in the present invention, various systems such as a DC power source, a pulse power source, a low-frequency / high-frequency AC power source, and a microwave power source can be used. Among them, an AC power source of 50 Hz or 60 Hz that can easily obtain a high voltage at a low cost and does not require a matching circuit is preferable, and specifically, an inverter neon transformer or a wound neon transformer is preferable.

  The amount of plasma generated in the present invention is affected by the distance between the electrode disposed in the air above the water surface and the water surface and the applied voltage. The applied voltage is low when the distance between the electrode disposed in the air above the water surface and the water surface is short, and the applied voltage is high when the distance is long. In the present invention, the distance between the electrode disposed in the air above the water surface and the water surface and the applied voltage are not limited. The electrode may be in a state slightly separated from the water surface, and is preferably larger than 0 mm and not larger than 50 mm. As a range where stable application and good dispersion can be expected, 2 to 10 mm is more preferable. The applied voltage is preferably greater than 0 kV and not greater than 30 kV in consideration of safety and electrode wear. Furthermore, 1-10 kV is the most preferable from the ease of applying a voltage.

  The dispersion medium for dispersing the solution, that is, the powder used when generating plasma in the present invention is not limited as long as it is water or an aqueous solution. In order to obtain an aqueous dispersion from which extra substances such as impurities that may adhere to the powder are eliminated, purified water, ion-exchanged water, pure water, ultrapure water, or the like may be used. In addition, in order not to lose the effect of the surface treatment agent coated with the present invention, addition of a salt for adjusting the conductivity of the solution, acid / alkali as a surface reaction aid, for enhancing dispersion stability You may add dispersing agents, such as alcohol and surfactant, to a dispersion medium.

  The apparatus for generating plasma in the present invention may be in a state where the upper surface of the water surface is released as shown in FIG. 1 or in a state where the device is sealed so as to cover the electrode on the upper surface of the water surface. In a closed system, discharge can be performed while introducing an arbitrary gas. If the apparatus is in an air atmosphere, the effect of active species such as radicals generated by the action of plasma on nitrogen, oxygen and water molecules in the air can be expected. Examples of the gas to be introduced include gases such as hydrogen, nitrogen, oxygen, argon, and carbon dioxide, mixtures thereof, and gasified compounds. The gas may be introduced either on the water surface or in the dispersion medium.

  In the pretreatment with plasma in the present invention, in order to enhance the effect and uniformity of the plasma, it is preferable to use a mechanical dispersion force in combination with the aqueous dispersion in which the powder is dispersed. Here, the mechanical dispersion force is the ability to agitate the aqueous dispersion in which the powder is dispersed to make the dispersion state of the powder in water and the radicals generated by the plasma uniform in water, When the dispersed powder is agglomerated, it means the ability to disperse the agglomerated particles by applying physical force such as impact or shear to the agglomerated particles.

  For example, in an anchor-type stirring blade or disper, the aqueous dispersion is agitated in order to disperse the powder in water and to make the action of radicals and the like uniform on the powder. Furthermore, in addition to stirring to make the entire system uniform, as a device to break up powder agglomerates and create new powder surfaces so that radicals etc. can act, the generated coarse and dense state Ultrasonic baths and ultrasonic homogenizers that use the disappearance of cavities generated due to expansion and expansion, high-speed homomixers and colloid mills that use powerful shearing and impact forces generated in the minute gaps between the rotating blades and the stationary ring, Examples include, but are not limited to, a high-pressure homogenizer using high-pressure / high-speed collision of an aqueous dispersion and a bead mill using collision / shear / impact / friction with a medium.

  In addition, the powder concentration in the aqueous dispersion when the plasma is generated and pretreated in the present invention is such that the viscosity of the aqueous dispersion is not too high so that the effect of the plasma is spread throughout the dispersion medium. It is preferably 20% by weight or less which can be sufficiently stirred by force.

  In the present invention, since the plasma is generated by immersing the powder in water, it is spherical, spindle-shaped, unlike the processing that specializes in film and plate planes such as plasma spray devices and atmospheric pressure plasma devices in the gas phase. The radicals generated by the plasma can be applied to the powder without being affected by the shape of the plate, the concave, etc., or the fine structure of the powder surface such as the porous material. For example, as long as the water is touched, the plasma can be applied to the back surface of the powder even in the form of a plate, or even in the concave portion of the powder.

In the present invention, it is possible not only to disperse in water, but also to disperse while agglomerating fine particles that are easy to agglomerate. For this reason, the more easily agglomerated powder is compared with other plasma treatments, the subsequent metal soap, perfluoroalkylethyl phosphate diethanolamine salt, fluoroalkyl acrylate / polyalkylene glycol acrylate polymer, perfluoropolyether phosphate, perfluoropolyether. Efficient surface treatment to coat a surface treatment agent such as an anionic or cationic polymer having a fluoropolyether chain, hydrogenated lecithin, acylated amino acid, α-tocopherol phosphate ester salt, silicone oil, silane compound, etc. be able to. For powders of 10 μm or less used in cosmetics, the method of generating plasma of the present invention gives good results in the subsequent coating of the surface treatment agent, and among them, fine particles commonly used for UV protection A preferable coating effect is shown for fine particles of 100 nm or less such as titanium oxide.

As described above, the powder aqueous dispersion obtained by the plasma pretreatment method in the present invention, or the powder is taken out of the aqueous dispersion, and the metal soap, perfluoroalkylethyl phosphate diethanolamine salt, fluorine Alkyl acrylate / polyalkylene glycol acrylate polymer, perfluoropolyether phosphate, anionic or cationic polymer having perfluoropolyether chain, hydrogenated lecithin, acylated amino acid, α-tocopherol phosphate ester salt, silicone oil, Although coating with a surface treatment agent such as a silane compound is performed, it is easier to coat the surface treatment agent using the aqueous dispersion of powder as it is because of the small number of steps.

  When the aqueous dispersion of powder is used as it is in the surface treatment step, the powder is treated with a surface treatment agent by a normal liquid phase method (wet method). Specifically, the surface treatment agent is added to the aqueous dispersion of the powder obtained by the plasma pretreatment of the present invention by adding the surface treatment agent in advance with water or alcohol or without diluting the surface treatment agent. There is a method of adsorbing to the surface of the powder. In addition, a divalent metal salt, a trivalent metal salt, an acid, an alkali, etc. are optionally added within a range not losing the plasma pretreatment effect of the present invention, and the surface treatment agent is deposited on the surface of the powder. Methods and the like. Thereafter, moisture and solvent are removed by filtration, decompression operation, heating, freeze-drying method, spray-drying method, fluidized granulation method and the like to obtain a surface-treated powder.

  In the case where the surface treatment is performed after the powder is taken out from the aqueous dispersion of the powder pretreated by the plasma generation method used in the present invention, the above method for removing moisture and solvent such as filtration, heating, spray drying method, etc. The powder is taken out using, and surface treatment is performed by a reaction method (dry method) in a gas phase such as a gas phase method or a mechanochemical method of a normal powder surface treatment method. In addition, the powder taken out from the aqueous dispersion may be dried to such an extent that the powder does not aggregate in the stirring step in the gas phase method.

  In the dry method described above, the surface treatment agent is added to the powder stirred in the gas phase by diluting with water or alcohol in advance or without dilution, and if necessary, metal salt, acid, alkali And the like, and then heating and the like to react and dry the surface treatment agent to obtain a surface treated powder.

In the present invention, as the surface treatment agent to be coated on the surface of the powder pretreated with plasma, metal soap, perfluoroalkyl ethyl phosphate diethanolamine salt, fluoroalkyl acrylate / polyalkylene glycol acrylate polymer, perfluoropolyether Phosphoric acid, anionic or cationic polymer having a perfluoropolyether chain, hydrogenated lecithin, acylated amino acid, α-tocopherol phosphate ester salt, silicone oil, silane compound, or a mixture of two or more of these Use.

  Examples of the amphiphilic substance used in the present invention include metal soap, perfluoroalkyl ethyl phosphate diethanolamine salt, fluoroalkyl acrylate / polyalkylene glycol acrylate polymer, perfluoropolyether phosphate, and perfluoropolyether chain. Anionic or cationic polymer (polyurethane-27 or polyurethane-26), hydrogenated lecithin, acylated amino acid, α-tocopherol phosphate ester salt and the like can be mentioned. What is necessary is just to have a hydrophilic part and a hydrophobic part, and to show an adsorption | suction characteristic to powder, and either a monomer type or a polymer type may be sufficient.

  Examples of the silicone oil used in the present invention include methyl hydrogen polysiloxane, α-monoalkoxypolydimethylsiloxane, α-dialkoxypolydimethylsiloxane and α-trialkoxypolydimethylsiloxane, triethoxysilylethylpolydimethylsiloxyethyl dimethicone. , Triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone, amodimethicone and the like.

  Examples of the silane compound used in the present invention include triethoxycaprylylsilane, aminopropyltriethoxysilane, perfluorooctylethyltriethoxysilane, and perfluorooctyltriethoxysilane.

  As the powder to be surface-treated as a raw material for cosmetics in the present invention, for example, in the case of inorganic substances, titanium oxide, bengara, zinc oxide, black iron oxide, yellow iron oxide, chromium oxide, chromium hydroxide, Gunjo, conger, carbon black, Alumina, hydroxyapatite, calcium carbonate, barium sulfate, aluminum powder, titanium mica, kaolin, anhydrous silicic acid, magnesium aluminum silicate, synthetic phlogopite, sericite, talc, boron nitride, mica and the like. Examples of organic substances include hemp cellulose powder, wheat starch, silk powder, aluminum stearate, zinc stearate, polyethylene powder, nylon powder, polyalkyl acrylate, cross-linked polystyrene, methylsiloxane network polymer, polyurethane and the like. Note that the powder to be surface-treated in the present invention may be a mixture or a composite thereof.

  In the present invention, since the above-mentioned powder is immersed in water and pretreated with plasma, it is easy to aggregate, such as titanium oxide, bengara, zinc oxide, black iron oxide, yellow iron oxide, alumina, and anhydrous silicic acid. A plasma can be made to act even on an object or an anisotropy in shape.

  In the present invention, since a good surface-treated powder can be obtained by pretreatment using plasma and subsequent coating with a surface treatment agent, when this surface-treated powder is blended in cosmetics, surface treatment without pretreatment by plasma A cosmetic material superior in water repellency, stability, feeling of use and the like can be obtained than powder.

  Further, in the cosmetic of the present invention, in addition to the surface-treated powder, water, fats and oils, waxes, hydrocarbons, fatty acids, alcohols, alkyl glyceryl ethers, esters, which are components blended in ordinary cosmetics, Silicone oil, fluorine oil, polyhydric alcohol, saccharide, polymer, surfactant, moisturizer, UV absorber, chelating agent, pH adjuster, antioxidant, bactericidal / preservative, dye, fragrance, pigment, plasticizer Organic solvents, drugs, animal and plant extracts, amino acids and peptides, vitamins, powders for cosmetics that are untreated or surface-treated by other methods, and the like can be appropriately blended.

  As in the present invention, in the process in which one electrode is in the air and the plasma is irradiated to the powder in the water, unlike the process in which the powder is placed in the air or on the water surface and discharged in the air, Since the powder spreads wet on the powder surface, radicals and the like can be made to act uniformly on the powder surface while pulverizing the powder aggregated in water. By utilizing this characteristic, it is possible to efficiently and uniformly perform surface treatment of powders that could not be processed due to the presence of agglomerated contact surfaces and powders of various shapes. From such a point of view, it is useful for surface treatment of anisotropic particles used in optical devices and the like, surface treatment of a molded body having a specific shape, and fuel cell materials that require surface uniformity.

FIG. 1 is a schematic view of a plasma generator.

  Hereinafter, a method for generating a plasma for the powder of the present invention to pre-process and a subsequent method for coating with a surface treatment agent will be described, but the present invention is not limited to these.

<Pretreatment>
As a pretreatment with plasma, fine titanium oxide was introduced into water with the apparatus shown in FIG. 1, and plasma was generated under the following conditions to obtain an aqueous dispersion containing fine titanium oxide of about 9% by weight. .
Target powder: 10 g of fine particle titanium oxide (MT-500B manufactured by Teika Co., Ltd., approximately spherical, average primary particle size 35 nm (catalog value))
Treatment solvent: 100 mL of ion exchange water
Plasma generator: Power source Winding neon transformer (60Hz)
Water surface top electrode Tungsten (Needle, 1mm diameter)
Counter electrode immersed in water Aluminum tape (flat plate)
Distance between water surface upper electrode and water surface 5mm
Applied voltage 1 to 5 kV
Storage tank: 200 mL beaker (made of glass)
Stirring: Ultrasonic cleaner (40 KHz, 55 W), anchor type stirring blade (20 rpm)
Plasma treatment time: 2 hours

<Coating of surface treatment agent>
Subsequently, the plasma generator was taken out of the above devices, and the powder was coated with the surface treatment agent using only the anchor type stirring blade. First, 1 g of sodium N-stearoyl-L-glutamate was dissolved in 10 g of ion-exchanged water, and the resulting mixture was gradually added dropwise to an aqueous dispersion of the fine particle titanium oxide (total amount: about 110 g) and stirred for 15 minutes. Thereafter, fine titanium oxide coated with sodium N-stearoyl-L-glutamate was obtained through filtration, washing, drying and pulverization steps.

(Comparative Example 1)
As Comparative Example 1, fine titanium oxide coated with sodium N-stearoyl-L-glutamate was obtained by treatment under the same conditions as in Example 1 except that no plasma was irradiated.
(Comparative Example 2)
As Comparative Example 2, plasma irradiation was not performed, but the N-stearoyl-L-glutamate sodium solution was added dropwise under the same conditions as in Example 1, and the aqueous dispersion was adjusted to pH 5 with 0.1 N (N) hydrochloric acid. After the pH of the mixture was lowered and the mixture was stirred for 15 minutes, in the same manner as in Example 1, filtration, washing, drying, and pulverization steps were performed to obtain finely divided titanium oxide coated with sodium N-stearoyl-L-glutamate.

<Water repellent performance evaluation>
The prepared surface treated powders of Example 1, Comparative Example 1 and Comparative Example 2 were placed in 0.5 g portions in each test tube containing 10 mL of ion exchange water, and the water repellency performance was compared.

<Result>
The surface-treated powder of Example 1 exhibited excellent water repellency while floating on the water surface. In Comparative Example 1 without plasma treatment, sedimentation started immediately after placing on the water surface, and the water repellency was insufficient. It was. In Comparative Example 2, it was initially floating, but partly settled after 1 hour. Accordingly, the water repellency is excellent in Example 1 according to the treatment method of the present invention, and the surface treatment effect of N-stearoyl-L-glutamate sodium is improved even by simply incorporating the treatment with a plasma apparatus as in the present invention into the process. did. In addition, the surface treatment effect was brought out to some extent by using hydrochloric acid in Comparative Example 2 in the preparation. However, additives such as the necessity of a large amount of water in the washing step and the possibility of residual salts. The method of Comparative Example 2 is disadvantageous when it is desired to perform surface treatment with a small amount.

  Regarding the feeling of use of the surface-treated fine particle titanium oxide, the surface-treated powder of Example 1 was a powder with a feeling of use that was more crisp and moist than the original fine particle titanium oxide. Since the surface treatment was not sufficient in Comparative Example 1, a rough feeling and a squeaky feeling remained, and although Comparative Example 2 was improved over Comparative Example 1, the moist feeling was still insufficient.

<Application to powder foundation>
Surface treatment of each powder by the same process as in Example 1 0.5 g of N-stearoyl-L-glutamate sodium was added to Example 1 for 10 g of each powder of sericite, talc, pigment grade titanium oxide and zinc oxide. A surface treatment process was performed under the same conditions to obtain a treated product of each powder of sodium N-stearoyl-L-glutamate.

Next, the following powder foundation was prepared using the above treated N-stearoyl-L-glutamate.
(Prescription)
Ingredient Amount (wt%)
1. N-stearoyl-L-glutamate sodium treated fine particle titanium oxide
(Example 1) 7.00
2. N-stearoyl-L-glutamate-treated sericite 34.10
3. N-stearoyl-L-glutamate sodium-treated talc 15.00
4). N-stearoyl-L-sodium glutamate treated pigment grade titanium oxide
8.00
5. N-stearoyl-sodium L-glutamate treated zinc oxide 2.00
6). Zinc stearate 1.00
7). Methylparaben 0.50
8). Silicone-treated yellow iron oxide 1.60
9. Silicone treated bengara 0.50
10. Silicone-treated black iron oxide 0.30
11. Silicic anhydride 4.00
12 Barium sulfate 5.00
13. Boron nitride 3.00
14 (Dimethicone / vinyl dimethicone / methicone) cross polymer 1.00
15. Polymethyl methacrylate 6.00
16. Methylpolysiloxane 7.00
17. Di-2-ethylhexyl succinate 4.00
Total 100.00
<Preparation method>
Ingredients 1 to 15 were uniformly mixed with a Henschel mixer, and pulverized with an atomizer. Furthermore, the mixed pulverized product of components 1 to 15 and components 16 and 17 were uniformly mixed with a Henschel mixer and pulverized with an atomizer, passed through a sieve, and pressed into an inner dish to obtain a powder foundation.

<Evaluation of usability of powder foundation>
When the above-mentioned powder foundation was evaluated for use feeling, it was very smooth and moist. Moreover, even when it was applied in the morning and in the afternoon, it was good without being damaged by drying. From these evaluation results, it was determined that the surface treatment effect of sodium N-stearoyl-L-glutamate was sufficiently exhibited.

  The fine particle titanium oxide in Example 1 was replaced with Bengala-coated mica titanium, which is one of the pearling agents, and plasma pretreatment was performed under the same conditions as in Example 1. Subsequently, 3.0 g of a 10 wt% potassium stearate aqueous solution as a surface treatment agent was gradually added dropwise and stirred for 15 minutes. After that, Bengala-coated mica titanium coated with stearic acid was obtained through filtration, washing, drying, and pulverization steps.

(Comparative Example 3)
As Comparative Example 3, Bengala-coated mica titanium coated with stearic acid was obtained under the same conditions as in Example 2 except that no plasma was irradiated.

<Evaluation of water repellency>
The water repellency was evaluated by the same method as described above. The stearic acid-treated pearl agent of Example 2 showed good water repellency and its color tone was not significantly different from that of the untreated one. On the other hand, Comparative Example 3 settled in water and its water repellency was insufficient.

(Comparative Example 4)
As Comparative Example 4, a 10% by weight potassium stearate aqueous solution was added dropwise to 5.0 g under the same conditions as in Comparative Example 3, and further a 1% by weight magnesium chloride aqueous solution was aggregated and floated in water. It was dripped gradually until. Thereafter, Bengala-coated mica titanium coated with magnesium stearate was obtained through steps of filtration, washing, drying, and pulverization.

<Evaluation of water repellency and appearance>
The water repellency was evaluated by the same method as described above. Comparative Example 4 did not settle in water and had good hydrophobicity. However, the color tone and gloss of the original Bengala-coated mica titanium were impaired.

  In general, the pearl agent often used in makeup cosmetics has a plate shape having a major axis of about 10 to 100 μm, and sufficient surface treatment is rarely performed in the surface treatment. For this reason, when a commercially available surface-treated pearl agent is tested for water repellency as in Example 1, it often settles in water, and in an emulsified system, a surfactant or the like due to surface treatment defects. In many cases, the adsorption of the resin occurs gradually and the emulsion stability is impaired. In order to improve this, usually, the amount of the surface treatment agent is increased to cope with it. However, if the amount is excessively increased, the color tone and gloss of the untreated pearl agent are often greatly deviated. The result of Example 2 shows that if the present invention is used, the amount of the surface treatment agent is suppressed and a good surface treatment effect can be obtained without the addition of a metal salt.

<Application to liquid foundation>
Using the pearl agent which performed the surface treatment of Example 2, the W / O emulsion type liquid foundation was prepared by the following prescription.
(Prescription)
Ingredient Amount (wt%)
1. Stearic acid-treated bengara-coated mica titanium
(Example 2) 2.00
2. Silicone-treated titanium oxide 11.00
3. Silicone-treated yellow iron oxide 2.00
4). Silicone treated bengara 0.30
5. Silicone-treated black iron oxide 0.20
6). Silicone-treated talc 3.00
7). Silicone-treated zinc oxide 5.00
8). Dimethylsilylated silica 0.50
9. Alkyl polyether co-modified silicone 1.00
10. Polyglyceryl diisostearate 0.50
11. Polyether-modified silicone 1.50
12 Diphenylsiloxyphenyl trimethicone 4.00
13. Cyclopentasiloxane 16.00
14 Trimethylsiloxysilicic acid 2.00
15. Ethylhexyl methoxycinnamate 4.00
16. Purified water 36.85
17. Edetate disodium 0.05
18. Methylparaben 0.10
19. Ethanol 10.00
Total 100.00
<Preparation method>
Components 1 to 15 were uniformly mixed with a high-speed homomixer, and components 16 to 19 were uniformly dissolved, and the mixture was stirred to obtain a W / O emulsion type liquid foundation.

(Stability of liquid foundation)
The prepared liquid foundation was stored at 40 ° C. for 1 month and observed over time. As a result, the state of re-emulsification performed by shaking at the time of use was also good, and there was no difference from that stored at room temperature. On the other hand, what was prepared by changing the component 1 to the pearl agent of Comparative Example 3 was insufficient in re-emulsification and was liable to cause separation of the aqueous phase. Therefore, the pearl agent subjected to the surface treatment using the plasma treatment of the present invention has also contributed to the improvement of the emulsion stability.

  As Example 3, pre-treatment with plasma was performed under the same conditions as in Example 1 except that the fine particle titanium oxide of Example 1 was replaced with sericite. Subsequently, about 10 g of sericite taken out by filtration, washing, drying and pulverization was put in an electric coffee mill, 0.3 g of methyl hydrogen polysiloxane was added and stirred at a high speed. Thereafter, the powder was taken out and reacted at 150 ° C. for 3 hours to obtain silicone-treated sericite.

  When the water repellency was confirmed by the same method as in Example 1, there was no sediment and the water repellency was good. On the other hand, in the commercially available sericite treated with 3% silicone, a part of it settled.

  As Example 4, the pretreatment by plasma was similarly performed by changing the fine particle titanium oxide of Example 1 to 20 g, and 2 g of sodium N-stearoyl-L-glutamate was similarly surface-treated.

  When the water-repellent performance was confirmed with respect to the obtained treated powder of Example 4 in the same manner as in Example 1, it was good without sediment.

  As Example 5, the fine particle titanium oxide of Example 1 was changed to 1 g, and N-stearoyl-L-glutamate sodium was changed to 0.1 g, and plasma pretreatment and subsequent surface treatment in the present invention were carried out in Example 1. The same operation was performed.

  The treated powder of Example 5 was also good when the same water repellency performance evaluation as in Example 1 was performed.

  According to the present invention, it is possible to bring out an excellent surface treatment effect by applying a surface treatment to the powder surface without using an additive or a dispersant or suppressing the amount of the additive or the dispersant. In addition, even in the agglomerated state in water, this can be solved in the plasma pretreatment stage. Since the surface portion of the powder covered with water can act with active components such as radicals by plasma, the surface treatment agent is uniformly coated. The surface-treated powder of the present invention can be widely used for cosmetics, inks, drugs, ceramics, industrial fillers, fuel cell materials and the like.

DESCRIPTION OF SYMBOLS 1 Storage tank 2 Dispersion medium which disperse | distributes powder in water 3 Power supply 4 Electrode installed in the air above the surface of water 5 Counter electrode immersed in water or in contact with water 6 Ceramic tube 7 Plasma

Claims (2)

For the powder charged in water, one of the pair of electrodes is immersed in water or brought into contact with the water surface, the other is placed in the air above the water surface, and a voltage is applied between both electrodes to generate plasma. The powder is obtained by irradiating the plasma with a method of generating water, or the powder is taken out from the aqueous dispersion, metal soap, perfluoroalkyl ethyl phosphate diethanolamine salt, fluorine alkyl acrylate / polyalkylene Selected from glycol acrylate polymer, perfluoropolyether phosphate, anionic or cationic polymer having perfluoropolyether chain, hydrogenated lecithin, acylated amino acid, α-tocopherol phosphate ester salt, silicone oil and silane compound powder, characterized in that one or more surface treatment agent coating process Surface treatment method.   The surface treatment method according to claim 1, wherein the powder is a metal oxide.