WO2006132465A1

WO2006132465A1 - Method for preparing the surface-modified powder with water-repellent thin layer

Info

Publication number: WO2006132465A1
Application number: PCT/KR2006/000592
Authority: WO
Inventors: Sang Hoon Jeon; Sun Sang Kwon; Duck Hee Kim; Ih Seop Chang
Original assignee: Amorepacific Corporation
Priority date: 2005-06-10
Filing date: 2006-02-22
Publication date: 2006-12-14
Also published as: CN101193618B; KR100930874B1; KR20060128353A; CN101193618A

Abstract

Disclosed herein is a method for preparing a powder having a surface modified with a water-repellent ultra-thin layer. The disclosed preparation method comprises modifying the powder with the water-repellent ultra-thin layer by a vapor phase reaction using a high-boiling-point acryl silicone OEt-based compound and branched alkyl-silicone OEt-based compound and an alkylsilane having relatively low boiling point. When the powder is used in cosmetics, it shows excellent usability due to improved water repellency.

Description

[DESCRIPTION] [Invention Title]

METHOD FOR PREPARING THE SURFACE-MODIFIED POWDER WITH WATER-REPELLENT THIN LAYER

[Technical Field]

The present invention relates to a method for preparing a powder modified with an ultra-thin layer by a vapor phase reaction using a high- boiling point acryl silicone OEt-based compound and branched alkyl-silicone OEt-based compound and an alkylsilane having a relatively low boiling point.

[Background Art]

Prior powders, which are frequently used in cosmetics, have inherent characteristics. To improve the shortcomings of such powders, techniques of modifying the surface in accordance with characteristics required in cosmetics are frequently used. Among these techniques, a coating technique is frequently used to convert the surface nature of powder from a hydrophilic nature into a hydrophobic nature or from a hydrophobic nature to a hydrophilic nature. Powders which are used in cosmetics can be classified as follows.

Inorganic pigments in cosmetics can be broadly divided, according to the function, into coloring pigments, white pigments, extender pigments and functional pigment.

The coloring pigments serve to adjust the color tone of products, and examples thereof include Bengala, iron oxide yellow, iron oxide black, chromium oxide, and carbon black. The white pigments can adjust coverage in addition to color tone, and examples thereof include titanium dioxide and zinc oxide. The extender pigments are diluents which are used to adjust color tone and, at the same time, to adjust the touch (extensibility or adhesion) or gloss of products and to maintain the formulation of products. Specific examples thereof include talc, kaolin and mica.

Talc is magnesium silicate hydrate (Mg₃Si₄θio(OH)₂) and is generally composed of a compact of fine crystals or an aggregate of foliar crude crystals. Also, it feels very soft, and talc particles are plate-like in shape and are frequently used in cosmetics to improve extensibility or smoothness.

Kaolin is so called "china clay" and derived from the name of the Chinese town Kao-Ling, where high-purity white clay used as the raw material of porcelain was produced. Kaolin has a composition of aluminum silicate hydroxide (Al₂Si₂Os(OH)₄) and shows a regular hexagonal plate-like shape at high crystallinity, but has a fine irregular plate-like shape at low crystallinity. Furthermore, it has excellent adhesion to the skin, because the thickness of the plate-like particles is small. Also, it is frequently used in cosmetics, because it has oil absorption and water absorption properties.

Mica is typically exemplified by muscovite belonging to potassium mica and is represented by a chemical formula of KAl₂(AlSi₃)Oio(OH)₂. The mica consists of lemon yellow or green hexagonal plate-like crystals belonging to the monoclinic system. It is also known as silk mica (sericite)", which is the same as muscovite, consists of aggregates of fine crystals and shows silk gloss on the surface. The functional pigments have various effects of blocking UV light and enhancing the usability or effect of products. Examples thereof include photochromic pigments, synthetic fluorine mica, iron-containing synthetic fluorine phlogopite and particulate composite powders.

The facial skin well painted indoors shows a phenomenon that the entire face looks white and swollen outdoors with strong light. If the color of makeup is adjusted according to the intensity of light, an ideal makeup that maintains natural finishing without giving the white and swollen look will be achieved. In other words, if a pigment having a brightness which changes according to the intensity of light is developed, a makeup which does not give the white and swollen look is possible. Pigments developed for this purpose are titanium dioxide-based pigments, which are prepared by adding a small amount of metal oxide to titanium oxide and show a reversible change in color when irradiated with light and also a change in brightness according to the intensity of light.

In addition, various organic powders have been developed and used in cosmetics. Typical examples thereof may include polyethylene powder, polymethylmethacrylate powder, polyethyleneterphtalate polymethylmethacrylate laminate powder, nylon powder, and cellulose derivatives.

Such cosmetic powders get loose at a long time after application to the skin and are easily washed away with sweat or water due to low water repellency. Also, because these powders are likely to aggregate with each other due to low oil resistance, these are agglomerated together by sweat or the like, so as to clog the skin pores, thus making skin respiration difficult.

To improve skin adhesion, long-lasting effect, water resistance and oil resistance, which are the shortcomings of the inorganic powders among such cosmetic powders, the surface of the powders is treated using suitable methods. In other words, the surface of the powders is coated with oily components, and alternatively, these powders are surface-treated with fatty acid, metal soaps of fatty acids, silicone compounds, fluorine derivative compounds or the like. Such methods for modifying the surface of the powders are mostly carried out by a wet process. These wet surface treatment methods have the following problems depending on various powders. In the method of coating the powder surface with oily components and fatty acids, the water resistance of the powder surface is improved to increase water repellency, however, if a hydrophobic component is present, an powder agglomeration phenomenon will occur, in which powders are agglomerated with each other due to the attractive force between a modified component on the surface of the powder and the surrounding hydrophobic component. Thus, if a cosmetic product containing these powders is applied to the skin, this phenomenon will be more accelerated due to sweat or the like. To overcome this problem, a technology of modifying the powder surface with a silicone/silane polymer to simultaneously impart water resistance and oil resistance was developed. For example, Korean Patent Publication No. 2004-64112 discloses a technology of modifying the powder surface by a vapor phase reaction process using low-boiling-point alkylsilane or the like. However, this technology has a problem in that the gaseous byproduct Si-H or Si-OH of silicone is dangerous at high temperatures.

Recently, fluorine-containing polymers have been used for the modification of the surface of powders. Although powders modified with a variety of such developed coating materials overcome many shortcomings, it is still difficult to uniformly form a coating film on the surface of particles to be modified. In other words, the method for modifying the powder surface using wet coating has a limitation. Meanwhile, silicone has excellent water resistance and oil resistance, but it is not coated in a uniform thickness and does not achieve uniform surface modification, so that it has a reduced affinity for biological components constituting the skin, thus causing heterogeneity. Also, this is likewise in the case of the fluorine-containing polymer. Therefore, the wet coating process makes it difficult to perform molding and processing in the production of cosmetics.

Meanwhile, in addition to the surface modification methods using the wet coating process, technologies of using a sol-gel process among processes for preparing organic/inorganic composites have been studied. These technologies can be broadly divided into four categories. The first is to use a sol-gel monomer containing carbon-silicon bonds. However, the organic reactive group will be present on the surface, because it does not participate in hydrolysis and condensation for forming a matrix. The second is to collect an organic substance mixed with a sol blend. The third is to impregnate an organic substance into gel using adsorption or the like. The fourth is to polymerize aniline or pyrrole in a vanadium oxide layer by intercalation.

Such organic/inorganic composites will find use particularly in electrochemical applications. Among such technologies using sol-gel, a water-repellent technology using silicone was developed and is suitably applied in cosmetics. Silicone, which is used as a water-repellent agent, is a methyl hydrogen oil emulsion having Si-H bonds, which forms a coating film at low temperatures. When the Si-H bonds of the silicone oil emulsion are allowed to react with the surface of a matrix by thermal treatment, new siloxane bonds are formed and, at the same time, a hydrogen bond between a hydrogen atom on the surface of the matrix surface and the oxygen atom of the silicone oil is formed. Also, the silicone oil emulsion becomes a three- dimensional structure having hydrophobic methyl groups oriented outward, and covers the surface of the matrix to fomi a durable coating film. The silicone coating film formed on the matrix as described above has the effect of imparting water repellency. In the case where the methyl hydrogen silicone oil is used as the raw material of a water repellent agent, the more the Si-H bonds, the lower the thermal treatment temperature for finishing, but the touch of the product is hard. To finish making the touch soft, a methyl hydrogen silicone oil containing dimethyl siloxane is sometimes used. Also, to facilitate the reaction of the Si-H bonds at low temperatures, metal organic acid or like is used as a catalyst.

However, the above technology also has the problem in that it is difficult to prepare powders imparted with excellent water repellency. In the case of using various alkylslianes, because it is difficult to control the reaction temperature and other parameters in the preparation process, it is not easy to form a uniform coating film, so that the mass production of powders has many limitations.

[Disclosure]

[Technical Problem)

Accordingly, in order to overcome the problems occurring in the surface modification using the prior coating method and to develop a new cosmetic, the present inventors have made efforts to develop a technology of forming an ultra-thin coating layer on the surface of powder by a physical and chemical vapor reaction process using a high-boiling-point water-repellent agent.

Therefore, it is an object of the present invention to provide a method for preparing a powder modified with a water-repellent ultra-thin layer by a vapor phase reaction using a high-boiling-point water-repellent agent.

[Technical Solution]

To achieve the above object, the present invention provide a method for preparing a powder having a surface modified with a water-repellent ultra- thin layer, the method comprising the steps of: (1) a milling step of milling a powder to be surface-modified, to a uniform particle size; (2) a first surface modification step of adsorbing a vaporized coating substance onto the surface of the milled powder using a water-repellent agent having a high boiling point of 100-250⁰C; and (3) a second surface modification step of further modifying the surface of the powder using a compound containing double bonds.

[Description of Drawings]

FIG. 1 shows a principle for measuring contact angle.

[Best Mode]

Hereinafter, the present invention will be described in further detail. The present invention relates to a method for forming a uniform, water-repellent, ultra-thin coating layer on a powder such as titanium dioxide, silica, mica or talc, which are frequently used in cosmetics. The vapor phase reaction process in the present invention is a known technology used for coating a semiconductor, in which a coating substance is deposited on a substrate such as a silicon wafer in a plasma state under high temperature and high pressure to modify the surface of the substrate.

The inventive method for preparing the powder having the surface modified with the water-repellent ultra-thin layer comprises the steps of: (1) a milling step of milling a powder to be surface-modified, to a uniform particle size; (2) a first surface modification step of adsorbing a vaporized coating substance onto the surface of the milled powder using a water-repellent agent having a high boiling point of 100-250⁰C; and (3) a second surface modification step of further modifying the surface of the powder using a compound containing double bonds.

Hereinafter, each step of the inventive preparation method will be described in further detail.

(1) Step of milling the powder to be surface-modified, to a uniform particle size

In the step (1), the powder to be surface-modified is milled to a uniform particle size of 2-15 μm by a suitable means such as a jet mill or a dry ball mill.

(2) First surface modification step of adsorbing the vaporized coating substance onto the surface of the milled powder using the water-repellent agent

The step (2) is the first surface modification step, in which the vaporized coating substance is first adsorbed onto the surface of the powder having a uniform particle size in a fluidized reactor. In the present invention, as a water-repellent agent for imparting water repellency to the desired powder, an acryl silicone OEt-based compound, a branched alkyl-silicone OEt-based compound or the like, which have a high boiling point of 100- 25O⁰C, is used alone or in a mixture with alkylsilane having a relatively low boiling point.

Examples of the acryl silicone OEt-based compound include an acrylate/tridecyl acrylate/triethoxysilypropyl methacrylate/dimethicone methacrylate copolymer, an acrylate/dimethicone aopolymer, an acrylate/dimethicone acrylate/ethylhexyl acrylate copolymer, an acrylate/stearyl acrylate/dimethicone acrylate copolymer, an acrylate/behenyl acrylate/dimethicone acrylate copolymer, an acrylate/ethylhexyl acrylate/dimethicone methacrylate copolymer and the like.

Also, examples of the branched alkyl-silicone OEt-based compound include triethoxysilyethyl polydimethylsiloxyethylhexyl dimethicone, triethoxysilyethyl polydimethylsiloxyethyl dimethicone and the like.

In addition, examples of alkylsilane coating agents, which can be used in the present invention, include trimethyl siloxy silicate, methyl hydrogen polysiloxane, hexamethyl cyclotrisiloxane, octamethyl polysiloxane, methyl cyclopolysiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, tetradecamethyl cycloheptasiloxane, triethoxycaprylyl silane and the like, but are not limited thereto. Meanwhile, to impart water repellency to powder, the high-boiling- point acryl silicone OEt-based compound or branched alkyl-silicone OEt- based compound is preferably used in a mixture with the alkylsilane coating agent.

(3) The second surface modification step of further modifying the surface using the compound containing double bonds

The step (3) is the second surface modification step which uses alkene and vinyl-terminated polysiloxane, which contains double bonds. The double bonds present in the compound used for the secondary surface modification react with Si-H formed on the surface of the powder in the first surface modification step, and the reaction rate in the second surface modification step is controlled using a platinum catalyst. Examples of the second surface modification compound include 1 -tetradecene, 1-dodecene, vinyl-terminated poly(dimethylsiloxane) and the like.

The characteristic of the second modification step is that the generation of hydrogen gas, which can occur in a final product when the Si-H group formed on the surface of the milled powder remains, can be inhibited, and that the water repellency of the powder can be increased.

The first and second surface modification steps of the present invention will now be described in further detail.

The concrete construction of the first and second surface modification steps, which are carried out using a reactor, which can perform mixing and milling using high-pressure gas stream, is as follows.

(1) First, a suitable amount of fine powder to be coated is introduced into a fluidized reactor, in which it is mixed and milled while it is warmed to the same temperature as that of the substance used for surface modification. (2) The substance to be used for the first surface modification is introduced through a nozzle having attached thereto a device capable of heating the substance above the boiling point thereof and capable of controlling the pressure of the substance through the control of air flow rate.

The nozzle is connected with a pipe capable of carrying the vaporized surface modification substance, and is connected with an injection nozzle, which is disposed in the fluidized-bed reactor and can control pressure and temperature. In the fluidized reactor, a nozzle opening which can perform mixing and milling using air pressure is located, and in the outside of the nozzle opening, the injection nozzle is located. The bottom of the reactor has a plurality of air passage holes perforated therethrough, which are used to fluidize the inside of the reactor. Herein, the flow rate of the vapor phase effluent from the high-pressure nozzle is most preferably about 0.5-2 kg/αif, and may also exceed the above-specified range. The temperature of the powder in the reactor and the temperature of a cylinder for the introduction of the powder were maintained at a temperature higher than the boiling point of the surface modification compound. For the physical and chemical adsorption of the vaporized surface modification compound, the temperature in the reactor is maintained 0.1-10⁰C lower than the boiling temperature of the surface modification compound, and the residence time of the compound in the reactor is controlled to 2-3 hours. In the upper portion of the reactor, a filter having a fine membrane is disposed, and the powder sample is prevented from flowing out of the reactor. Also, the pressure of the filter is measurable to examine the state of the filter, and a damper is provided to enable the inside of the reactor to be smoothly fluidized.

(3) After completion of the first surface modification as described above, the second surface modification is carried out. For the second surface modification, two methods are possible. In other words, if the above apparatus is used, the vaporization of the second surface modification compound is possible, and if the vaporization is impossible, a wet coating system can be used. Through the second surface modification, a relatively long hydrocarbon chain is produced on the surface of the powder, so that the powder can exhibit uniform and improved water repel lency. The present invention has advantages in that, because it dose not require other steps except for a process control factor for the fhiidization of pigment particles in the prior coating process, it can simplify process steps, and also the uniform ultra-thin layer formed on the powder can eliminate the agglomeration of the particles. Furthermore, because a precise coating amount of the coating substance is used in the reaction through the optimization of the process, unnecessary coating can be eliminated.

[Mode for Invention] Hereinafter, the present invention will be described in further detail with reference to Examples and Comparative Examples. It is to be understood, however, that these examples are not to be construed to limit the scope of the present invention.

Example 1 : First surface modification using acrylate/tridecyl acrylate/triethoxysilypropyl methacrylate/dimethicone methacrylate copolymer Thereinafter, referred to as "coating mixture 1 "

600-900 g of each of finely powdered titanium dioxide, talc, mica and sericite was introduced in a fluidized reactor, and then the coating mixture 1 represented by Formula 1 below was introduced into a feed cylinder. Then, the coating mixture 1 was vaporized by heating it to about 200⁰C, which is higher than the boiling point of the coating mixture 1. The coating mixture was passed through the heating device of a nozzle unit using air as a carrier gas, and then vaporized and introduced into the fluidized reactor. Herein, the coating mixture was introduced into the fluidized reactor at a rate of about 0.5-2.0 kg/cm² through the nozzle. The residence time of the coating mixture in the fluidized reactor was 2-3 hours, and the vaporized coating mixture formed an ultra-thin layer on the surface of the powder through the reaction between the Si-OEt of the coating mixture and the powder in the main reactor. [Formula 1]

Example 2: First surface modification using triethoxysily ethyl polydimethylsiloxyethylhexyl dimethicone (hereinafter, referred to as "coating solution 2"

As described in Example 1 above, 600-900 g of each of finely powdered titanium dioxide, talc, mica and sericite was introduced into a main reactor, and then the coating mixture 2 represented by Formula 2 below was introduced into a feed cylinder. Then, the coating mixture 2 was vaporized by heating it to about 160⁰C, which is higher than the boiling point of the coating mixture 2. The coating mixture 2 was passed through the heating device of a nozzle unit using air as a carrier gas, and then vaporized and introduced into the fluidized reactor. Subsequent steps were carried out in the same manner as in Example 1. [Formula 2]

*

Example 3: First surface modification using mixture of triethoxy carpryryl silane and acrylate/tridecyl acrylate/triethoxysilypropyl methacrylate/dimethicone methacrylate copolymer (hereinafter, referred to as "coating mixture 3"

600-900 g of each of finely powdered titanium dioxide, talc, mica and sericite was introduced into a fluidized reactor, and then the coating mixture 3 was introduced into a feed cylinder. Then, the coating mixture 3 was vaporized by heating it to about 120-200⁰C depending on the mixing ratio between the components of the coating mixture 3. Said temperature is a temperature higher than the boiling temperature of the coating mixture 3.

The coating mixture 3 was passed through the heating device of a nozzle unit using air as a carrier gas, and then vaporized and introduced into the fluidized reactor. Subsequent steps were carried out in the same manner as in

Example 1.

Example 4: First surface modification using mixture of triethoxy carpryryl silane and triethoxysilyethyl polydimethyl siloxyethylhexyl dimethicone (hereinafter, referred to as "coating solution 4"

600-900 g of each of finely powdered titanium dioxide, talc, mica and sericite was introduced into a fluidized reactor, and then the coating mixture 4 was introduced into a feed cylinder. Then, the coating mixture 4 was vaporized by heating it to about 120-200⁰C depending on the mixing ratio between the components of the coating mixture 4. Said temperature is a temperature higher than the boiling temperature of the coating mixture 4. The coating mixture 4 was passed through the heating device of a nozzle unit using air as a carrier gas, and then vaporized and introduced into the fluidized reactor. Subsequent steps were carried out in the same manner as in Example 1. Example 5: Second surface modification (vapor phase coating) of powder subjected to first surface modification using coating mixture 3

About 12O g of each of the first-surface-modified powders prepared in

Example 3 above was introduced into a main reactor and then subjected to vapor phase reaction with 1-tetradecene introduced into a feed cylinder. Herein, organic metal catalyst H₂PtCl₆ was used and the reaction temperature was maintained at about 6O⁰C.

Example 6: Second surface modification (vapor phase coating) of powder subjected to first surface modification using coating mixture 4

About 12O g of each of the first- surface-modified powders prepared in Example 4 above was introduced into a main reactor and then subjected to vapor phase reaction with 1-tetradecene introduced into a feed cylinder.

Herein, organic metal catalyst H₂PtCl₆ was used and the reaction temperature was maintained at about 6O⁰C.

Example 7: Second surface modification (wet coating) of powder subjected to first surface modification using coating mixture 3

15 g of the first-surface-modified powder prepared in Example 3 was introduced into a three-neck round bottom, to which about 45 ml of ethanol was then added. The solution was uniformly stirred. Then, 0.002 ml of organic metal catalyst H₂PtCl₆ was added thereto. Then, 0.1-0.4 mol of 1- dodecene or vinyl-terminated polydimethylsiloxane as a second coating compound was added thereto, and then the second surface modification of the powder was performed by stirring the mixture for about 2-3 hours while maintaining the reaction temperature at 70⁰C.

Example 8: Second surface modification (wet coating) of powder subjected to first surface modification using coating mixture 3 15 g of the first-surface-modified powder prepared in Example 4 was introduced into a three-neck round bottom, to which about 45 ml of ethanol was then added. The solution was uniformly stirred. Then, 0.002 ml of organic metal catalyst H₂PtCl₆ was added thereto. Then, 0.1-0.4 mol of 1- dodecene or vinyl-terminated polydimethylsiloxane as a second coating compound was added thereto, and then the second surface modification of the powder was performed by stirring the mixture for about 2-3 hours while maintaining the reaction temperature at 7O⁰C.

Comparative Example 1 : Surface modification using triethoxy carpryryl silane (TCS) 350 g of each of titanium dioxide, talc and mica was introduced into a main reactor, and then triethoxy carpryryl silane (TCS) was introduced into a feed cylinder and vaporized by heating it to a temperature of about 86-9O⁰C, which is higher than the boiling point of TCS. The vaporized TCS was introduced into the main reactor using inert nitrogen gas as carrier gas. Herein, the vaporized TCS was introduced into the main reactor at a rate of about 100-150 m/sec through a nozzle. The residence time of the vaporized TCS in the main reactor was 2-3 hours, and it was allowed to react with the pigment particles in the main reactor to form an S-H group on the surface of the particles.

Comparative Example 2: Second surface modification (vapor phase coating) of powder subjected to first surface modification

About 120 g of each of the first-surface-modified powders prepared in

Comparative Example 1 above was introduced into a main reactor and then subjected to vapor phase reaction with 1-tetradecene introduced into a feed cylinder. Herein, organic metal catalyst H₂PtCl₆ was used and the reaction temperature was maintained at about 6O⁰C.

Comparative Example 3: Second surface modification (wet coating) of powder subjected to first surface modification

15 g of the powder, which has been surface-modified with TCS in

Comparative Example 1 , was introduced into a three-neck round bottom, to which about 45 ml of ethanol was then added. The solution was uniformly stirred. Then, 0.002 ml of organic metal catalyst H₂PtCl₆ was added thereto.

Then, 0.1-0.4 mol of 1-dodecene or vinyl-terminated polydimethylsiloxane as a second coating compound was added thereto, and then the second surface modification of the powder was performed by stirring the mixture for about 2- 3 hours while maintaining the reaction temperature at 7O⁰C.

Experimental Example 1 : Comparison of water repellency

Powders, which have been typically used in cosmetics, were compared with each other with respect to water repellency after performing the first surface modification thereof in Examples above. In other words, titanium dioxide, talc and mica, which are typical powders, were compared with each other with respect to water repellency after performing the first surface modification thereof using vapor phase reaction.

The measurement of water repellency was performed by measuring contact angle in the following manner.

Measurement of contact angle Contact angle is a measure of the wettability of a solid surface and is generally measured by a drop of water. Low contact angle shows high wettability (hydrophilic) and high surface energy, and high contact angle shows low wettability and (hydrophobic) and low surface energy. The contact angle of liquid to a flat solid surface is measured at the contact point between the end point of a water drop curve and the solid surface at a liquid- solid-gas interface.

A principle for the measurement of contact angle is shown in FIG. 1.

To measure contact angle, a solid surface must be flat. Then, a drop of water falls on the solid surface. The diameter of the water drop must generally be in the range of several mm. A double-sided adhesive film having excellent shear adhesion is fixed to a slide glass, and each of the first- surface-modified samples was formed into a flat plate and measured for contact angle.

The measurement results are shown in Table 1 below. Also, the powders subjected to second surface modification in Examples 5 to 8 were measured for contact angle, and the measurement results are shown in Table 2 below.

Table 1 : Comparison of measurement results for contact angle

As can be seen in Table 1 above, the powders subjected to the first surface modification all showed a significant increase in water repellency compared to the untreated powder. Also, the branched alkyl-silicone OEt- based compound was slightly higher in water repellency than acryl silicone OEt-based compound, and the mixtures with alkylsilane were lower in water repellency than the undiluted solution.

Table 2: Comparison of measurement results for contact angle

As can be seen in Table 2 above, the powders subjected to the second surface modification showed an increase in water repellency compared to that of the powders subjected to the first surface modification, and the vapor coating process provided an increase in water repellency compared to the wet coating process. This suggests that the reaction on the powder surface more uniformly occurred in the vapor coating process than the wet coating process.

Test Example 2: Comparison of usability

The comparison of usability between the powders was performed with respect to adhesion and spreadability. The two factors were measured using a rheometer, in which the spreadabilty was expressed as the friction g force (gl) between an initial rubber and an application surface, and the adhesion was expressed as (gl-g2)/gl x 100 using g force (g2) obtained in the second measurement after the first measurement. The measurement value (gl) of the spreadability and the measurement value ((gl-g2)/gl x 100) of the adhesion must preferably be low. The measurement results are shown in Tables 3 and 4 below.

Table 3: Comparison of measurement results for usability (after first coating)

As can be seen in Table 3 above, the powder whose surface was treated with the "coating mixture 1 " showed the best improvement in adhesion among all the powders, and the powder whose surface was treated with the "coating mixture 2" showed the best improvement in spreadability.

Table 4: Comparison of measurement results for usability (after first coating)

As can be seen in Table 4, although there was no great change after the second coating following the first coating, 1 -tetradecene among the second coating compounds showed better adhesion compared to 1 -dodecene.

Meanwhile, the cosmetic composition according to the present invention has no particular limitation in the formulation thereof. For example, the inventive cosmetic composition can be formulated into skin lotion, astringent lotion, milk lotion, nourishing cream, essence, eye cream, body lotion, body cream, body gel, foundation, makeup base, base powder, lipstick, lip gloss, lip liner, mascara eyebrow, eye shadow, nail enamel, hair foam, hair cream or hair mascara.

Formulation Example 1 : Preparation of nail enamel

Formulation Example 2: Preparation of lipstick

Formulation Example 3: Preparation of oil-in-water emulsion-type pearl foundation

Formulation Example 4: Preparation of face powder (powder pack (powder pack)

[Industrial Applicability]

As described above, the present invention provides the method for preparing the powder modified with the ultra-thin layer by vapor reaction using a high-boiling-point acryl silicone OEt-based compound and branched alkyl-silicone OEt-based compound and an alkylsilane having a relatively low boiling point. According to the present invention, high temperature is stably maintained, and thus various bases having high boiling point can be used for surface treatment. The range of the bases can be enlarged from low- molecular-weight bases having limited properties to high-molecular- weight bases. Also, substances having the desired properties, which are used as the bases, can be screened from a wide range of substances.

In other words, in the prior art, the bases to be used in surface treatment have been limited. However, according to the present invention, the desired substances can be designed with respect to usability sections such as adhesion or spreadability in addition to water repellency and can be selectively used for surface treatment. Also, the correlation between a wider range of surface treatment bases can be ensured by analyzing and examining the bases with respect to water repellency, adhesion and spreadability.

Claims

[CLAIMS]

[Claim 1 ]

A method for preparing a powder having a surface modified with a water-repellent ultra-thin layer, comprising the steps of: (1) a milling step of milling a powder to be surface-modified, to a uniform particle size;

(2) a first surface modification step of adsorbing a vaporized coating substance onto the surface of the milled powder using a water-repellent agent; and (3) a second surface modification step of further modifying the surface of the powder using a compound containing double bonds, in which the water-repellent agent is selected from the group consisting of an acryl silicone OEt-based compound and a branched alkyl-silicone OEt- based compound, which have high boiling point.

[Claim 2]

The method of Claim 1, wherein the acryl silicone OEt-based compound is at least one selected from the group consisting of an acrylate/tridecyl acrylate/triethoxysilypropyl methacrylate/dimethicone methacrylate copolymer, an acrylate/dimethicone copolymer, an acrylate/dimethicone acrylate/ethylhexyl acrylate copolymer, an acrylate/stearyl acrylate/dimethicone acrylate copolymer, an crylate/behenyl acrylate/dimethicone acrylate copolymer and an acrylates/ethylhexy acrylate/dimethicone methacrylate copolymer.

[Claim 3]

The method of Claim 1 , wherein the branched alkyl-silicone OEt-based compound is at least one selected from the group consisting of triethoxysilyethyl polydimethylsiloxyethylhexyl dimethicone and triethoxysilyethyl polydimethylsiloxyethyl dimethicone.

[Claim 4]

The method of Claim 1, wherein the water-repellent agent used in said step (2) is used in a mixture with alkylsilane.

[Claim 5]

The method of Claim 4, wherein the alkylsilane is at least one selected from the group consisting of trimethyl siloxy silicate, methyl hydrogen polysiloxane, hexamethyl cyclotrisiloxane, octamethyl polysiloxane, methyl cyclopolysiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, tetradecamethyl cycloheptasiloxane, triethoxycaprylyl silane.

[Claim 6] The method of Claim 1, wherein the temperature in a reactor used in the step (2) is maintained 0.1-10⁰C lower than the boiling point of the vaporized coating substance in order to physically and chemically adsorb the coating substance onto the powder, while the residence time of the coating substance in the reactor is controlled to 2-3 hours.

[Claim 7]

The method of Claim 1, wherein the vaporized coating substance is introduced into a reactor through a nozzle having a controlled air influx, and the flow rate of the vaporized coating substance sprayed from the nozzle is 0.5-2 kg/ciif.

[Claim 8]

The method of Claim 1, wherein the compound having double bonds is an alkene compound or a vinyl-terminated siloxane compound.

[Claim 9]

The method of Claim 8, wherein the compound having double bonds is selected from the group consisting of 1 -tetradecene, 1- 1-dodecene and vinyl-terminated poly(dimethylsiloxane).

[Claim 10]

A cosmetic composition containing a powder prepared according to any one of Claims 1 to 9.