JP4865388B2 - Surface-treated zinc oxide powder and cosmetics containing the same - Google Patents

Description

  The present invention relates to a surface-treated zinc oxide powder and a cosmetic containing the same, and more particularly to imparting hydrophobicity to a zinc oxide powder used in a cosmetic and improving the wash-out property.

  In cosmetics, in particular, makeup cosmetics, the aesthetic effect that makes a person look beautiful is natural, and the sustainability of the effect, that is, the longevity of makeup is also required as one of the extremely important performances. For this reason, in the development of cosmetic bases, improvement of makeup retention has become an important issue. In the field of makeup cosmetics, oily bases are often used so that makeup collapse does not occur due to moisture such as sweat, tears or saliva. When the powder is blended, separation from the base is likely to occur, and the hydrophilic powder flows out due to moisture, which is a major cause of makeup collapse. Because of these problems, conventionally, when powders are blended in cosmetics, it has been widely practiced to blend hydrophobic powders that have been previously hydrophobized.

  Many methods are known for hydrophobizing cosmetic powders, such as higher fatty acids, higher alcohols, hydrocarbons, triglycerides, esters, silicone oils, silicone resins such as silicone resins, or fluorine compounds. A method of applying hydrophobicity to the powder by coating the surface of the hydrophilic powder is used. Among them, since the hydrophobic treatment of powder using silicones as a surface treatment agent can impart particularly excellent hydrophobicity, many methods have been established so far (for example, Patent Document 1, Patent Document 1). 2). In recent years, a method of using a copolymer of acrylic acid or an acrylic ester as a powder surface treatment agent is also known (see, for example, Patent Document 3).

  On the other hand, in cosmetics, its washability is also required as one of the important performances. However, when the above-described conventional hydrophobized powder is blended, it can improve makeup durability, but it can be easily washed away with water even if soap is used because of its excellent hydrophobicity. Can not. For this reason, oil-based washing-off preparations are widely used, but this oil-based preparation needs to be washed away with soap or the like, which places a heavy burden on the user. Further, when a hydrophilic powder is blended for the purpose of facilitating washing off, as described above, makeup collapse is likely to occur, resulting in inferior makeup. For this reason, it is a very difficult task to satisfy both performances at the same time, being able to maintain its effect for a long time while applying makeup, while being able to wash off easily when removing makeup. Met.

JP-A-60-16397 JP-A-62-177070 JP-A-8-337514

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a surface-treated zinc oxide powder that is excellent in hydrophobicity and improved in washing out property, and a cosmetic containing the same. There is.

  As a result of the inventors' diligent research in view of the above-mentioned problems, a zinc oxide powder treated so that the zinc ion elution amount is 30 ppm or less is used as a base powder, and an acrylic system having a specific structure on the surface thereof. It was found that by coating a polymer containing a derivative as a constituent monomer, a surface-treated zinc oxide powder excellent in hydrophobicity-hydrophilicity change under an appropriate pH condition can be obtained. As a result, it was found that when the surface-treated zinc oxide powder is blended in cosmetics, it can be easily washed away with water using soap or the like, even though it has excellent makeup. The present invention has been completed.

（式中、Ｒ^１は水素又は炭素数１〜３のアルキル基、Ｒ^２は炭素数４〜２２のアルキレン基、Ｘ^１は−ＮＨ−基又は酸素原子、Ｍ^１は水素又は１価の無機又は有機カチオンを表す。） That is, the surface-treated zinc oxide powder according to the present invention is further formed on the surface of the zinc oxide powder-based powder treated so that the zinc ion elution amount measured by the following test method 1 is 30 ppm or less. A polymer containing the monomer (A) represented by the general formula (1) as a constituent monomer is coated.
[Test Method 1]
The zinc oxide powder is dispersed in water so as to be 0.01% by mass, and the pH of the dispersion is adjusted to maintain 7.5. The dispersion is centrifuged, and the zinc ion concentration (ppm) is measured for the supernatant after separation to obtain the zinc ion elution amount.

(In the formula, R ¹ is hydrogen or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 4 to 22 carbon atoms, X ¹ is an —NH— group or an oxygen atom, M ¹ is hydrogen or a monovalent inorganic group. Or represents an organic cation.)

  Moreover, in the surface-treated zinc oxide powder, it is preferable that the zinc oxide-based powder is a zinc oxide powder that has been treated so that the zinc ion elution amount is 22 ppm or less. In the surface-treated zinc oxide powder, it is preferable that the zinc oxide-based powder is a zinc oxide powder treated with carboxyl-modified silicone. In the surface-treated zinc oxide powder, it is preferable that the carboxyl-modified silicone is a carboxyl-modified silicone having a COOH equivalent of 500 to 5000 g / mol.

  In the surface-treated zinc oxide powder, the polymer is preferably a polymer containing monomer (A) in an amount of 70 mol% or more based on the total amount of constituent monomers. In the surface-treated zinc oxide powder, it is preferable that the polymer further contains a monomer (B) represented by the following general formula (2) as a constituent monomer.

（式中、Ｒ^３は水素又は炭素数１〜３のアルキル基、Ｒ^４は炭素数１〜４のアルキレン基、Ｘ^２は−ＮＨ−基又は酸素原子、Ｍ^２は水素又は１価の無機又は有機カチオンを表す。）

(Wherein R ³ is hydrogen or an alkyl group having 1 to 3 carbon atoms, R ⁴ is an alkylene group having 1 to ⁴ carbon atoms, X ² is an —NH— group or an oxygen atom, and M ² is hydrogen or a monovalent inorganic group. Or represents an organic cation.)

  In the surface-treated zinc oxide powder, it is preferable that the coating amount of the polymer with respect to the zinc oxide-based powder is polymer: powder = 3: 97 to 40:60 in mass ratio. The cosmetic according to the present invention is characterized by containing the surface-treated zinc oxide powder.

  The surface-treated zinc oxide powder according to the present invention is excellent in hydrophobicity, and its washability is remarkably improved. For this reason, when the surface-treated zinc oxide powder of the present invention is blended in a cosmetic, it can be easily washed away with water using soap or the like even though it has excellent makeup.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The surface-treated zinc oxide powder according to the present invention further has the above general formula on the surface of the zinc oxide-based powder treated so that the zinc ion elution amount measured by the following test method 1 is 30 ppm or less. A polymer containing the monomer (A) represented by (1) as a constituent monomer is coated.
[Test Method 1]
The zinc oxide powder is dispersed in water so as to be 0.01% by mass, and the pH of the dispersion is adjusted to maintain 7.5. The dispersion is centrifuged, and the zinc ion concentration (ppm) is measured for the supernatant after separation to obtain the zinc ion elution amount.

Zinc Oxide-Based Powder In the surface-treated zinc oxide powder according to the present invention, the zinc oxide powder used as the base powder is treated so that the zinc ion elution amount measured by the test method 1 is 30 ppm or less. Zinc oxide powder. The test method used in the present invention will be described in detail below.

First, the zinc oxide powder to be tested is dispersed in water so as to be 0.01% by mass. Then, the dispersion is adjusted with, for example, a Tris buffer or a NaCl aqueous solution so that the pH of the dispersion is maintained at 7.5.
Subsequently, the zinc oxide powder dispersion is centrifuged. In centrifugation, a normal commercially available centrifuge may be used. In addition, the centrifugation speed, time, etc. may be adjusted as appropriate, but in normal cases, it is performed at 5000 to 50000 rpm for about 10 to 120 minutes.

  Collect an appropriate amount of the supernatant after centrifugation and measure the zinc ion concentration (ppm) in the liquid. A method for measuring the zinc ion concentration is not particularly limited, and examples thereof include an ICP (inductively coupled plasma analysis) method, an atomic absorption photometric analysis method, and an ion chromatography method. Further, for example, it is also possible to measure the zinc ion concentration (ppm) in the liquid using a commercially available measuring device such as an atomic absorption spectrophotometer (manufactured by Varian) or an ion chromatogram (manufactured by Hitachi). .

  The zinc oxide powder used as the base powder in the present invention is a zinc oxide powder treated so that the zinc ion elution amount measured by the test method 1 is 30 ppm or less. If the zinc ion elution amount exceeds 30 ppm, the eluted zinc ions bind to carboxyl groups in the polymer and adversely affect the pH responsiveness, so that the resulting surface-treated zinc oxide powder has sufficient pH responsiveness. It may not be obtained. In addition, as zinc oxide group powder used for this invention, it is preferable that the zinc ion elution amount is 22 ppm or less further.

  The raw material for zinc oxide powder before treatment used in the present invention is not particularly limited, and in addition to untreated zinc oxide powder, zinc oxide powder previously coated with silica, alumina or the like may be used. I do not care. For example, untreated zinc oxide, hydrophobized zinc oxide prepared by the production method described in WO99 / 25654, and commercially available zinc oxide powder raw materials include, for example, FINEX-50,75 (untreated zinc oxide, Mozuchi Chemical Co., Ltd.), MZ-500 (untreated zinc oxide, manufactured by Teika Co., Ltd.), AZO-BS (alumina coated zinc oxide, manufactured by Shodo Chemical Co., Ltd.), Activox C-80 (silica coated zinc oxide, Harcross Duhram) And LU-173 (silica-coated zinc oxide, manufactured by Ishihara Sangyo Co., Ltd.). In the present invention, alumina-coated zinc oxide or silica-coated zinc oxide can be particularly preferably used from the viewpoint of suppressing elution of zinc ions. In addition, even if it is a commercially available zinc oxide raw material, as long as the zinc ion elution amount measured by the said test method 1 is 30 ppm or less, you may use as it is as the zinc oxide base powder of this invention.

  As the zinc oxide-based powder of the present invention, in general, the zinc oxide elution amount measured by the test method 1 is 30 ppm by previously treating the zinc oxide powder raw material with an optional treatment agent. It adjusts and uses so that it may become the following. The treating agent is not particularly limited, and examples thereof include silicone compounds such as carboxyl-modified silicone, fluorine compounds such as perfluoroalkyl phosphoric acid, silica, fatty acids, dextrin palmitate, and the like. Of these treatment agents, carboxyl-modified silicone can be most preferably used in the present invention. Examples of the carboxyl-modified silicone used in the present invention include BY16-750, BY16-880 (all manufactured by Toray Dow Corning), X22-3710, X22-162C, and X22-3701E (all manufactured by Shin-Etsu Silicone). Etc.

  In the carboxyl-modified silicone used as the zinc oxide treating agent of the present invention, for example, a functional group containing a carboxyl group (for example, —R—COOH; R is an alkyl group) is introduced into the side chain and / or terminal of the linear silicone. Any compound may be used without particular limitation. In addition, in the carboxyl-modified silicone used in the present invention, when too few carboxyl groups are introduced, the hydrophobicity of the silicone becomes relatively strong, and the resulting surface-treated zinc oxide powder has a basic condition. It may not be possible to disperse even underneath. For this reason, in this invention, it is more suitable to use the carboxyl modified silicone whose COOH equivalent is 500-5000 g / mol. The COOH equivalent (g / mol) of the carboxyl-modified silicone exemplified above is shown below.

Product name COOH equivalent (g / mol)
BY16-750 (manufactured by Toray Dow Corning) 750
BY16-880 (manufactured by Toray Dow Corning) 3500
X22-3710 (manufactured by Shin-Etsu Silicone) 1450
X22-162C (manufactured by Shin-Etsu Silicone) 2300
X22-3701E (manufactured by Shin-Etsu Silicone) 4000

The surface-treated zinc oxide powder according to the present invention further contains the monomer (A) represented by the general formula (1) as a constituent monomer on the surface of the zinc oxide-based powder obtained as described above. The polymer to be coated is coated.
Polymer In the present invention, the polymer used as the surface treatment agent is a polymer containing the monomer (A) represented by the general formula (1) as a constituent monomer.
The monomer (A) represented by the general formula (1) is a compound in which a fatty acid is added in acrylic acid or alkyl-substituted acrylic acid, or acrylamide or alkyl-substituted acrylamide. In the general formula (1), R ¹ is hydrogen or an alkyl group having 1 to 3 carbon atoms. When R ¹ is an alkyl group, it may be linear or branched. R ¹ is preferably hydrogen or a methyl group. In the general formula (1), ^{R 2} is an alkylene group having 4 to 22 carbon atoms. The alkylene group may be linear or branched. Examples of R ² include an octylene group having 8 carbon atoms, an 11 undecylene group, and a 12 dodecylene group. R ² may include an aromatic ring or a carbon-carbon double bond in the structure, and may be, for example, a vinylene group, a methylphenylene group, a vinylphenylene group, or the like. In the general formula (1), X ¹ is a —NH— group or an oxygen atom, and particularly preferably a —NH— group. In the general formula (1), M ¹ is hydrogen or a monovalent inorganic or organic cation. The monovalent inorganic or organic cation is not particularly limited as long as it can form a salt of a carboxylic acid, and examples of the monovalent inorganic cation include sodium ion, potassium ion, lithium ion, and the like. Examples of the organic cation include ammonium ion, monoethanolammonium ion, triethanolammonium ion, and the like. Regarding M ¹ , after polymer production, it is reversibly converted into a carboxylic acid (M ¹ = hydrogen) or sodium salt (M ¹ = sodium) form using an appropriate amount of dilute hydrochloric acid or dilute sodium hydroxide solution. It is also possible.

  Examples of the monomer (A) used in the present invention include 11-methacrylamidoundecanoic acid, 8-acrylamidooctanoic acid, 12-acrylamidododecanoic acid, 12-methacrylamideamidododecanoic acid, and 3- {4-[(methacryloxy) methyl. ] Phenyl} acrylic acid and the like. In the polymer of the present invention, one or more of the monomers (A) can be used as a constituent monomer.

  In the polymer used in the present invention, it is preferable that the monomer (A) is contained in an amount of 70 mol% or more in the total amount of the constituent monomers. When the monomer (A) is less than 70 mol%, the hydrophobic-hydrophilic adjustment effect is small, and the desired performance may not be imparted to the powder. Further, the monomer (A) is particularly preferably 90 mol% or more. In addition, in the polymer concerning this invention, the said monomer (A) may occupy the whole quantity of a structural monomer.

Moreover, as a polymer of this invention, the monomer (B) shown by the said General formula (2) can be used suitably as structural monomers other than the said monomer (A).
The monomer represented by the general formula (2) is a compound in which an alkylsulfonic acid is added in acrylic acid or alkyl-substituted acrylic acid, or acrylamide or alkyl-substituted acrylamide. In general formula (2), ^{R 3} is an alkyl group having 1 to 3 carbon hydrogen or carbon. When R ³ is an alkyl group, it may be linear or branched. R ³ is preferably hydrogen or a methyl group. In the general formula (2), ^{R 4} is an alkylene group having 1 to 4 carbon atoms. The alkylene group may be linear or branched. Examples of R ⁴ include a methylene group, an ethylene group, and a propylene group, and an ethylene group and a propylene group are particularly preferable. In the general formula (2), ^{X 2} is an -NH- group or an oxygen atom, and particularly preferably -NH- group. In the general formula (2), M ² is hydrogen or a monovalent inorganic or organic cation. Any monovalent inorganic or organic cation may be used as long as it can form a sulfonic acid salt. Examples of the monovalent inorganic cation include sodium ion, potassium ion, lithium ion, and the like. Examples of the organic cation include ammonium ion, monoethanolammonium ion, triethanolammonium ion, and the like. Regarding M ² , after the production of the polymer, it is reversibly converted into a sulfonic acid (M ² = hydrogen) or sodium salt (M ² = sodium) form using an appropriate amount of dilute hydrochloric acid or dilute sodium hydroxide solution. It is also possible.

  Examples of the monomer represented by the general formula (2) include 2-acrylamido-2-methylpropanesulfonic acid, potassium 3-methacryloxypropanesulfonate, and the like.

In the polymer of the present invention, one or more of the monomers (B) represented by the general formula (2) can be used as a constituent monomer.
Moreover, in the polymer concerning this invention, it is suitable that the said monomer (B) is contained 1-30 mol% in the structural monomer whole quantity. If the monomer (B) is less than 1 mol%, the effect of the blending cannot be obtained, and if it exceeds 30 mol%, the content of the monomer (A) is relatively reduced, and the desired performance with respect to the powder. May not be granted.

  Moreover, the polymer of this invention can also contain monomers other than the said monomer (A) and (B) as a structural monomer, if it is a range which does not impair the effect of this invention. Content should just be the range of 30 mol% or less of a constituent monomer whole quantity, for example, can contain about 1-20 mol%. Examples of such monomers include acrylamide, methacrylamide, methyl acrylamide, methyl methacrylamide, dimethyl methacrylamide, ethyl acrylamide, ethyl methacrylamide, diethyl methacrylamide, N-isopropyl acrylamide, N-vinyl pyrrolidone, ε-caprolactam, Examples include vinyl alcohol, maleic anhydride, N, N′-dimethylaminoethyl methacrylic acid, diallyldimethylammonium chloride, alkyl acrylate, alkyl methacrylate, N, N′-dimethylacrylamide, and styrene.

  The polymer of the present invention can be obtained by polymerizing various monomers containing the above monomers using a known polymerization method. For example, homogeneous solution polymerization method, heterogeneous solution polymerization method, emulsion polymerization method, reverse phase emulsion polymerization method, bulk polymerization method, suspension polymerization method, precipitation polymerization method and the like can be used. For example, in the case of the homogeneous solution polymerization method, the polymer of the present invention can be obtained by dissolving various monomers in a solvent, adding a radical polymerization initiator under a nitrogen atmosphere, and stirring with heating. The polymer of the present invention can also be obtained by post-modification in which a functional group is added to polyacrylic acid or polyacrylamide.

  As a solvent used in the polymerization, any solvent can be used as long as it can dissolve or suspend various monomers and does not contain water. For example, methanol, ethanol, propyl alcohol Alcohol solvents such as isopropyl alcohol and butyl alcohol, hydrocarbon solvents such as hexane, heptane, octane, isooctane, decane and liquid paraffin, ether solvents such as dimethyl ether, diethyl ether and tetrahydrofuran, and ketone solvents such as acetone and methyl ethyl ketone Solvents, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, chloride solvents such as methylene chloride, chloroform, carbon tetrachloride, dimethylformamide, diethylformamide, dimethylsulfoxide, dioxane, etc. And the like. Two or more of these solvents may be used in combination. Usually, it is suitable to select a solvent having a boiling point higher than the starting temperature of the polymerization initiator to be used.

  The polymerization initiator is not particularly limited as long as it has the ability to initiate radical polymerization. For example, peroxide such as benzoyl peroxide, azobisisobutyronitrile (AIBN), 2,2′-azobis (Isobutyric acid) In addition to azo compounds such as dimethyl, persulfuric acid polymerization initiators such as potassium persulfate and ammonium persulfate may be mentioned. In addition, it can superpose | polymerize by photochemical reaction, radiation irradiation, etc. irrespective of these polymerization initiators. The polymerization temperature is not less than the polymerization start temperature of each polymerization initiator. For example, in the case of a peroxide-based polymerization initiator, the temperature may usually be about 50 to 70 ° C.

  The polymerization time is not particularly limited, but is usually about 30 minutes to 24 hours. When it is desired to obtain a polymer having a relatively high molecular weight, it is desirable to react for about 24 hours. If the reaction time is too short, unreacted monomers may remain and the molecular weight may be relatively small. The average molecular weight of the polymer of the present invention is not particularly limited, and the target effect can be exhibited as long as it has a polymerization degree equal to or higher than that of the oligomer. In addition, a copolymer in which various monomers are randomly added is usually obtained by mixing two or more monomers and performing polymerization.

The polymer used in the present invention has a carboxyl group derived from the monomer (A) in the polymer side chain, and this carboxyl group is a hydrophobic carboxylic acid (—COOH) under acidic to neutral conditions. Under basic conditions, it changes to a hydrophilic carboxylate ion (—COO ⁻ M ⁺ ). For this reason, the treated powder obtained by treating the surface of the powder with this polymer exhibits a pH-responsive hydrophobic-hydrophilic change such as hydrophobicity in an acidic to neutral environment and hydrophilicity in a basic environment. It seems that it comes to show.
And, when the surface-treated zinc oxide powder obtained in this way is blended in cosmetics, the cosmetics are excellent in long-lasting cosmetics because they exhibit hydrophobicity in the acidic to neutral regions where they are usually used. Nevertheless, when a moderate basic environment is made using soap or the like, the surface of the treated powder changes to hydrophilic, so that it can be easily washed away with water.

Further, in addition to the monomer (A), the polymer having the monomer (B) as a constituent monomer further has a sulfonic acid group derived from the monomer (B) in the polymer side chain. Exists as a hydrophilic sulfonate ion (—SO ₃ ⁻ M ⁺ ) in a very broad pH range. Therefore, by appropriately adjusting the monomer ratio of the monomer (A) and the monomer (B) in the constituent monomers to produce a polymer, the hydrophobic-hydrophilic balance imparted to the powder can be suitably adjusted. It becomes possible. For example, when the hydrophilicity imparted to the powder is to be increased, the ratio of the monomer (B) may be increased, and conversely, when the hydrophobicity is increased, the ratio of the monomer (A) can be increased. That's fine. Further, by using an appropriate amount of the monomer (B), the adsorptivity of the polymer to the powder can be enhanced.

  The polymer used in the present invention is adjusted so that the ratio of the monomer (A) to the monomer (B) is (A) :( B) = 70: 30 to 99.9: 0.1 in molar ratio. Is preferred. When the ratio of the monomer (A) is less than 70:30, the treated powder is biased toward hydrophilicity, so that sufficient hydrophobicity may not be imparted, while the ratio of the monomer (A) is 99. .9: When the ratio is more than 0.1, it is difficult for the polymer to be adsorbed on the surface of the powder, which may adversely affect the stability of the powder.

  In the surface-treated zinc oxide powder according to the present invention, the coating amount of the polymer with respect to the powder is, by mass ratio, polymer: powder = 3: 97 to 40:60, more preferably 5:95 to 30:70. . When the amount of polymer coating is less than 3:97, desired performance may not be imparted to the powder. When the amount of coating is larger than 40:60, the feeling of use when used as a cosmetic, etc. May have an adverse effect.

  In the surface-treated zinc oxide powder of the present invention, the surface treatment of the zinc oxide-based powder may be used by a usual treatment method, and the method is not particularly limited. For example, when a zinc oxide group powder is treated with the above polymer, a method in which the polymer is dissolved in an appropriate solvent such as ethyl alcohol, the powder is mixed and stirred in this solution, and then the solvent is distilled off. Alternatively, a method in which a polymer dissolved in a non-volatile oil such as a higher alcohol is directly mixed and stirred. Further, when the surface-treated zinc oxide powder according to the present invention is blended in a cosmetic, the polymer may be directly mixed and stirred in the base containing the zinc oxide-based powder in the cosmetic production process. .

Cosmetics The cosmetics according to the present invention are characterized by containing the surface-treated zinc oxide powder obtained as described above. The compounding amount of the surface-treated zinc oxide powder is preferably 3% by mass or more, and particularly preferably 5 to 95% by mass, based on the total amount of the cosmetic. If the blending amount is less than 3% by mass, the effects of the present invention may not be obtained.

  In the cosmetic according to the present invention, in addition to the above-described surface-treated zinc oxide powder, water, oil, powder (untreated), surfactant, which are usually used in cosmetics, as long as the effects of the present invention are not impaired. Ingredients such as fluorine compounds, resins, adhesives, preservatives, fragrances, UV absorbers, moisturizers, physiologically active ingredients, salts, solvents, antioxidants, chelating agents, neutralizing agents, pH adjusters, etc. Can do.

  The form of the cosmetic according to the present invention is not particularly limited. For example, makeup cosmetics such as foundation, white powder, lipstick, eye shadow, teak, mascara, eyeliner, sunscreen agent, base cream , Hair cream and the like.

Examples of the present invention are given below, but the present invention is not limited thereto.
First, a method for synthesizing the polymer used in the present invention will be described.

Synthesis Example 1 12: Methacrylamide dodecanoic acid (MAD) homopolymer

  40.0 g (141.34 mmol) of 12-methacrylamide decanoic acid (MAD) and 0.58 g (3.53 mmol) of azobisisobutyronitrile (manufactured by Nacalai Tesque) were dissolved in 120.0 g of methanol. Azobisisobutyronitrile was recrystallized from methanol in accordance with a conventional method. Degassing was carried out by bubbling argon for 60 minutes, and the container was covered with a septum and polymerized by heating at 60 ° C. for 20 hours. After completion of the polymerization reaction, the reaction solution was dropped into a large excess of diethyl ether, and the precipitate was collected by suction filtration. After drying under reduced pressure, 124.15 g of MAD homopolymer was obtained (yield: 60.4%).

Synthesis Example 2 11-methacrylamidoundecanoic acid (MAU) / 2-acrylamido-2-methylpropanesulfonic acid (AMPS) copolymer (90/10)

  11-methacrylamidoundecanoic acid (MAU) 18.42 g (68.41 mmol), 2-acrylamido-2-methylpropanesulfonic acid (AMPS: Sigma-Aldrich Japan) 1.58 g (7.60 mmol), hydroxylated 0.31 g (7.60 mmol) of sodium and 0.31 g (1.89 mmol) of azobisisobutyronitrile (manufactured by Nacalai Tesque) were dissolved in 59.4 g of methanol. Nitrogen was bubbled for 60 minutes for deaeration, and the vessel was covered with a septum and heated at 60 ° C. for 20 hours for polymerization. After completion of the polymerization reaction, the reaction solution was dropped into a large excess of ethyl acetate, and the precipitate was collected by suction filtration. After drying under reduced pressure, 17.8 g of random MAU / AMPS copolymer (90/10) was obtained (yield: 87.9%). The weight average molecular weight was 92,000.

  In order to examine the characteristics of the surface-treated zinc oxide powder that has been surface-treated with a polymer, the inventors first performed a surface treatment with the polymer of Synthesis Example 1 on the untreated zinc oxide powder. The treated powder was evaluated for water solubility under acidic (pH 5) and basic (pH 10) conditions. The evaluation results are shown in Table 1 and FIG. The production conditions and evaluation method of the surface-treated zinc oxide powder are as follows.

MAD homopolymer / untreated zinc oxide powder 10 g of MAD homopolymer produced in Synthesis Example 1 above was dissolved in 1000 g of ethanol, and further, untreated zinc oxide powder (prepared by the method described in WO99 / 25654) ) 90 g was mixed and dispersed, and ethanol was volatilized. The obtained massive substance was pulverized to obtain 92.1 g of MAD homopolymer / zinc oxide powder.

0.1 g of water-soluble surface-treated zinc oxide powder of the treated powder is put in a vial together with 30 mL of various pH buffered aqueous solutions of pH 5 and pH 10, mixed and stirred for 1 minute by a magnetic stirrer, and then the state of the solution is determined. confirmed.
○: The powder was uniformly dissolved in water to form a cloudy solution.
X: The powder did not dissolve in water and separated on the water surface.

  In the water solubility test, for example, when the powder does not disperse in water under the condition of pH 5, and the powder disperses in water under the condition of pH 10, when the powder is blended in cosmetics, Despite being excellent in makeup, it can be easily washed away with water. However, as shown in Table 1 and FIG. 1, the zinc oxide powder surface-treated with MAD homopolymer is uniformly dispersed in water under both acidic conditions of pH 5 and basic conditions of pH 10. Thus, it was revealed that the intended pH responsiveness was not obtained even though the polymer was coated with a pH responsive polymer.

With respect to the above results, the present inventors paid attention to the zinc ion elution amount of the zinc oxide powder used as the base powder. That is, it was considered that elution of zinc ions in the zinc oxide-based powder adversely affects the pH responsiveness of the resulting surface-treated zinc oxide powder.
From this, an attempt was made to suppress zinc ion elution by carboxyl-modified silicone treatment. The elution amounts of various commercially available or prepared zinc oxide powders and carboxyl-modified silicone-treated zinc oxide powders were measured and compared. The measurement results are shown in Table 2. In addition, the manufacturing method of carboxyl modified silicone-processed zinc oxide and the measuring method of the zinc ion elution amount are as follows.

Carboxyl-modified silicone / zinc oxide powder Carboxyl-modified silicone (X22-3710: manufactured by Shin-Etsu Silicone) 10.0 g was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of untreated zinc oxide powder (prepared by the production method described in WO99 / 25654) was added, mixed, and dispersed. The dispersion was stirred and mixed, and then dried to obtain 93.7 g of the target carboxyl-modified silicone / zinc oxide powder.

Zinc ion elution amount Various zinc oxide powders were stirred and dispersed in water to 0.01% by mass. The dispersion was adjusted with 50 mM Tris buffer and 100 mM NaCl aqueous solution so that the pH of the dispersion was maintained at 7.5. This dispersion was centrifuged with a high-speed cooling centrifuge (manufactured by Hitachi). 20 mL of the supernatant after separation was collected, and the zinc ion concentration (ppm) was measured with an IPC inductively coupled plasma analyzer (manufactured by Rigaku).

  As shown in Table 2 above, in various commercially available zinc oxide powders or prepared zinc oxide powders, the zinc ion elution amount was about 40 to 50 ppm. On the other hand, the zinc ion elution amount of the zinc oxide powder treated with carboxyl-modified silicone was 21.7 ppm, and it was confirmed that zinc ion elution was remarkably suppressed.

  Subsequently, the present inventors used a zinc oxide powder treated with carboxyl-modified silicone as a base powder, and further performed a surface treatment with a MAD homopolymer, and for the obtained polymer / carboxyl-modified silicone / zinc oxide powder, The water solubility of the treated powder was evaluated under acidic (pH 5) and basic (pH 10) conditions. The evaluation results are shown in Table 3 and FIG. In addition, the water-soluble evaluation result at the time of using a prepared zinc oxide powder and a hydrophobized zinc oxide powder as a comparative example is shown collectively. Moreover, the manufacturing conditions and evaluation methods of the surface-treated zinc oxide powder are as follows.

Example 1-1: MAD homopolymer / carboxyl-modified silicone / zinc oxide powder 10.0 g of carboxyl-modified silicone (X22-3710: manufactured by Shin-Etsu Silicone) was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of zinc oxide powder (prepared by the production method described in WO99 / 25654) was added and dispersed. The dispersion was stirred and mixed, and dried to obtain 93.7 g of carboxyl-modified silicone / zinc oxide powder. Separately, 10.0 g of the MAD homopolymer produced in Synthesis Example 1 above was dissolved in 1000 g of ethanol, and 90.0 g of the carboxyl-modified silicone / zinc oxide powder obtained above was added and mixed, and dried. 90.3 g of MAD homopolymer / carboxyl-modified silicone / zinc oxide powder was obtained.

  As shown in Table 3 and FIG. 2, the surface-treated zinc oxide powder of Example 1-1, in which a zinc oxide-based powder was used, a carboxyl-modified silicone / zinc oxide powder was used, and the surface was treated with a MAD homopolymer. In acidic conditions of pH 5, the powder is not dissolved in water at all, and the powder exhibits excellent hydrophobicity. On the other hand, in the basic condition of pH 10, the powder is not dissolved in water. It was revealed that the powder was uniformly dissolved and the powder changed to hydrophilic. That is, when the surface-treated zinc oxide powder of Example 1-1 is blended in cosmetics, it exhibits excellent hydrophobicity in the acidic to neutral region where general cosmetics are used, and is therefore excellent in makeup retention. Nevertheless, when a moderate basic environment is made using soap or the like, the surface of the powder changes to hydrophilic, so that it can be easily washed away with water.

  On the other hand, in Comparative Example 1-1 using the untreated zinc oxide powder, the powder was dissolved in water at both pH 5 and pH 10. In Comparative Example 1-2 using the hydrophobized zinc oxide powder, the powder was not dissolved at both pH 5 and 10. For these reasons, zinc oxide powders that are not coated with a pH-responsive polymer can completely change hydrophilicity-hydrophobicity in response to changes in pH, regardless of the difference between hydrophilicity and hydrophobicity. I understand that there is no.

  Subsequently, the present inventors prepared cosmetics containing various surface-treated zinc oxide powders, and evaluated the cleanability, water resistance, and UV protection ability of each cosmetic. The composition of the cosmetic and the evaluation results are shown in Table 4 below. In addition, the manufacturing conditions of the various surface treatment zinc oxide powder used for cosmetics, and the evaluation method of cosmetics are as follows.

Example 2-1
Dissolve 10.0 g of the MAD homopolymer prepared in Synthesis Example 1 in 1000 g of ethanol, and prepare 90.0 g of perfluoroalkyl phosphate-treated zinc oxide (prepared by the method described in JP-A-2005-232279, elution of zinc ions) (Amount: 18.5 ppm) was added, mixed and dried to obtain 92.0 g of MAD homopolymer / perfluoroalkyl phosphoric acid, alkyl dimethicone acrylate / zinc oxide powder of Example 2-1.

Example 2-2
5.0 g of silicic anhydride was added and mixed in 1000 ml of ethanol. In this solution, 95.0 g of petal-like zinc oxide was added, mixed and dispersed. The dispersion was stirred and mixed, and then dried to obtain 89.9 g of silica / zinc oxide powder (zinc ion elution amount: 19.2 ppm). Separately, 10.0 g of the MAD homopolymer produced in Synthesis Example 1 above was dissolved in 1000 g of ethanol, 90.0 g of the silica / zinc oxide powder obtained above was added and mixed, and dried to obtain Example 2- 28.5 g of 2 MAD homopolymer / silica / zinc oxide powder was obtained.

Example 2-3
10.0 g of carboxyl-modified silicone (X-22-3710: manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of zinc oxide (prepared by the production method described in WO99 / 25654) was added, mixed, and dispersed. The dispersion was stirred and mixed, and then dried to obtain 90.7 g of carboxyl-modified silicone / zinc oxide powder (zinc ion elution amount: 21.7 ppm). Separately, 10.0 g of the MAD homopolymer prepared in Synthesis Example 1 above was dissolved in 1000 g of ethanol, and 90.0 g of the carboxyl-modified silicone / zinc oxide powder obtained above was added and mixed, and dried. A 2-3 MAD homopolymer / carboxyl-modified silicone / zinc oxide powder (87.7 g) was obtained.

Comparative Example 2-1
The perfluoroalkyl phosphoric acid and alkyl dimethicone acrylate / zinc oxide powder (no surface treatment with MAD homopolymer) used in Example 2-1 was used as Comparative Example 2-1.

Comparative Example 2-2
The silica / zinc oxide powder (no surface treatment with MAD homopolymer) used in Example 2-2 was used as Comparative Example 2-2.

Comparative Example 2-3
88.0 g of carboxyl-modified silicone / zinc oxide powder of Comparative Example 2-3 was obtained under the same conditions as in Example 2-3 except that the surface treatment with MAD homopolymer was not performed.

Comparative Example 2-4
10.0 g of stearic acid was added and mixed in 1000 ml of ethanol. In this solution, 95.0 g of zinc oxide (prepared by the production method described in WO99 / 25654) was added, mixed, and dispersed. The dispersion was stirred and mixed, and then dried to obtain 91.7 g of stearic acid / zinc oxide powder of Comparative Example 2-4.

Comparative Example 2-5
Comparative Example 2-5 was prepared by using 90.0 g of zinc oxide palmitate treated with dextrin (prepared by the production method described in WO99 / 25654).

A 0.1 mL detergency sample was applied to a 10 cm × 5 cm range on the inner side of the forearm (2 μL / cm 2), dried for 15 minutes, and a sample of the applied portion (diameter range 2 cm) was extracted using 5 mL of acetone ( Before washing). After that, 2 mL of a commercial body soap is sufficiently bubbled, and the sample application part is washed so that it is stroked 5 times, then rinsed with water and dried, and a sample of the application part (with a diameter of 2 cm different from the previous one) is used with 5 mL of acetone. And extracted (after washing). For the acetone solution before and after cleaning, the amount of inorganic powder was quantified using ICP (inductively coupled plasma mass spectrometer), and how much inorganic powder remained in the acetone solution after cleaning with respect to the acetone solution before cleaning. Tested. The evaluation criteria are as follows.
A: Remaining amount less than 20% B: Remaining amount 20% or more and less than 30% C: Remaining amount 30% or more and less than 40 D: Remaining amount 40% or more

A 0.1 mL water resistant sample was applied to a 10 cm × 5 cm range on the inner side of the forearm (2 μL / cm ² ) and dried for 15 minutes. A sample of the coated part (diameter range 2 cm) was extracted with 5 mL of acetone (before washing). After the inner part of the forearm was placed in running water for 15 minutes, a sample of the coated part (a range of 2 cm in diameter different from the previous part) was extracted with 5 mL of acetone (after washing). About the acetone solution before and behind washing | cleaning, the light absorbency of 310 nm was compared and it was tested how much sample remained in the acetone solution after washing | cleaning with respect to the acetone solution before washing | cleaning. The evaluation criteria are as follows.
A: 85% or more remaining B: 75% or more and less than 85% remaining C: 65% or more and less than 75% remaining D: less than 65% remaining

Samples were used on a sunny day by 20 professional UV protection effect panels, and the UV protection effect was evaluated (a 2 μL / cm ² sample was applied to the inner part of the forearm and allowed to dry for 15 minutes). The evaluation criteria are as follows.
A: More than 16 out of 20 responded that the UV protection effect was good B: 12-15 out of 20 responded that the UV protection effect was good C: 6-11 out of 20 had UV protection effect Answer D: Good 5 out of 20 respondents say that UV protection is good

  As shown in Table 4 above, in the cosmetics of Examples 2-4 to 2-5 in which the surface-treated zinc oxide powders of Examples 2-1 to 2-3 were blended, detergency, water resistance, and ultraviolet light It showed an excellent effect on any of the protective effects. On the other hand, in the cosmetics of Comparative Examples 2-6 to 2-10 in which the surface-treated zinc oxide powders of Comparative Examples 2-1 to 2-5 were blended, those showing excellent effects in all evaluation items In particular, it was not possible to obtain a cosmetic having both excellent cleaning properties and water resistance.

  Hereinafter, the present invention will be described in more detail by giving other examples of the present invention. However, the present invention is not limited to these examples.

Example 3-1
Dissolve 10.0 g of the MAD homopolymer prepared in Synthesis Example 1 in 1000 g of ethanol, add 90.0 g of dextrin palmitate-treated zinc oxide (prepared by the method described in WO99 / 25654), mix and dry. Thus, 92.0 g of the MAD homopolymer / dextrin palmitate / zinc oxide powder of Example 3-1 was obtained.

Example 3-2
10.0 g of octyltriethoxysilane (manufactured by Nihon Unicar) was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of zinc oxide (prepared by the production method described in WO99 / 25654) was added, mixed, and dispersed. The dispersion was stirred and mixed, and then dried to obtain 90.2 g of octyltriethoxysilane / zinc oxide powder (zinc ion elution amount: 19.7 ppm). Separately, 10.0 g of the MAD homopolymer produced in Synthesis Example 1 above was dissolved in 1000 g of ethanol, and 90.0 g of the octyltriethoxysilane / zinc oxide powder obtained above was added and mixed, dried and carried out. 89.7 g of the MAD homopolymer / octyltriethoxysilane / zinc oxide powder of Example 3-2 was obtained.

Example 3-3
10.0 g of carboxyl-modified silicone (X22-3710: manufactured by Shin-Etsu Silicone) was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of zinc oxide powder (untreated zinc oxide, MZ-500: manufactured by Teika) was added and dispersed. The dispersion was mixed with stirring and dried to obtain 90.7 g of carboxyl-modified silicone / zinc oxide powder. Separately, 10.0 g of the MAU / AMPS copolymer (MAU / AMPS = 90/10) produced in Synthesis Example 2 above was dissolved in 1000 g of ethanol, and 90.0 g of the carboxyl-modified silicone / zinc oxide powder obtained above. Were mixed and dried to obtain 88.7 g of MAU / AMPS copolymer (MAU / AMPS = 90/10) / carboxyl-modified silicone / zinc oxide powder of Example 3-1.

Example 3-4
10.0 g of carboxyl-modified silicone (X22-3710: manufactured by Shin-Etsu Silicone) was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of zinc oxide powder (untreated zinc oxide, MZ-500: manufactured by Teika) was added and dispersed. The dispersion was mixed by stirring and dried to obtain 88.8 g of carboxyl-modified silicone / zinc oxide powder. Separately, 10.0 g of the MAU / AMPS copolymer (MAU / AMPS = 90/10) produced in Synthesis Example 2 above was dissolved in 1000 g of ethanol, and 90.0 g of the carboxyl-modified silicone / zinc oxide powder obtained above. Were added and mixed, and dried to obtain 86.7 g of MAU / AMPS copolymer (MAU / AMPS = 95/5) / carboxyl-modified silicone / zinc oxide powder of Example 3-2.

12-methacrylamide decanoic acid (MAD) / N-hydroxyethylacrylamide (HEAA) copolymer (90/10)
12.14-methacrylamidododecanoic acid (MAD) 19.14 g (67.63 mmol), N-hydroxyethylacrylamide (HEAA: manufactured by Kojin Co., Ltd.) 0.86 g (7.51 mmol), azobisisobutyronitrile (Nacalai Tesque) 0.33 g (1.97 mmol) was dissolved in 60.0 g of methanol. Azobisisobutyronitrile was recrystallized from methanol in accordance with a conventional method. Degassing was carried out by bubbling argon for 60 minutes, and the container was covered with a septum and polymerized by heating at 60 ° C. for 20 hours. After completion of the polymerization reaction, the reaction solution was dropped into a large excess of diethyl ether, and the precipitate was collected by suction filtration. After drying under reduced pressure, 16.90 g of MAD / HEAA copolymer (90/10) was obtained.

Example 3-5
10.0 g of carboxyl-modified silicone (X22-3710: manufactured by Shin-Etsu Silicone) was added and mixed in 1000 ml of ethanol. In this solution, 90.0 g of zinc oxide powder (untreated zinc oxide, MZ-500: manufactured by Teika) was added and dispersed. The dispersion was mixed by stirring and dried to obtain 88.8 g of carboxyl-modified silicone / zinc oxide powder. Separately, 10.0 g of the above MAD / HEAA copolymer (MAD / HEAA = 90/10) was dissolved in 1000 g of ethanol, and 90.0 g of the carboxyl-modified silicone / zinc oxide powder obtained above was added and mixed, followed by drying. As a result, 86.7 g of the MAD / HEAA copolymer (MAD / HEAA = 90/10) / carboxyl modified silicone / zinc oxide powder of Example 3-3 was obtained.

Example 3-6
Powder type foundation content (mass%)
(1) Surface-treated zinc oxide powder of Example 3-3 10.0
(2) Talc 40.7
(3) Sericite 24.3
(4) Titanium oxide 4.8
(5) Nylon powder 2.8
(6) Black iron oxide 0.2
(7) Yellow iron oxide 2.8
(8) Bengala 1.0
(9) Liquid paraffin 4.0
(10) Octyldodecyl myristate 3.0
(11) Sorbitan isostearate 3.0
(12) Octyldodecanol 3.0
(13) Preservative 0.1
(14) Bactericide 0.1
(15) Antioxidant 0.1
(16) Fragrance 0.1
(Manufacturing method) In addition to (9)-(12) which heat-dissolved (1)-(8), (13)-(16), it mixed with the Henschel mixer, and obtained the powder type foundation.
The powder-type foundation obtained as described above was excellent in long-lasting makeup and could be easily washed away with water using soap.

Example 3-7
Two-layer type W / O sunscreen compounding amount (% by mass)
(1) Talc 10.0
(2) Surface-treated zinc oxide powder of Example 3-4 10.0
(3) Isocetyl octanoate 5.0
(4) Decamethylcyclopentasiloxane 26.8
(5) Dimethylpolysiloxane 10.0
(6) POE-modified dimethylpolysiloxane 2.0
(7) Ion exchange water 28.0
(8) 1,3-butylene glycol 8.0
(9) Preservative 0.1
(10) Fragrance 0.1
(Manufacturing method) (3)-(6) was heat-mixed at 70 degreeC, and it was set as the oil phase. Separately, (8) and (9) were dissolved in (7) to make an aqueous phase. The powders (1) and (2) were added to the oil phase and dispersed with a homomixer. The previous aqueous phase was added to this and emulsified with a homomixer. Further, (10) was mixed and filled into a container.
The two-layer type W / O sunscreen obtained as described above was excellent in makeup retention and could be easily washed away with water using soap.

Example 3-8
Two-layer type W / O sunscreen compounding amount (% by mass)
(1) Talc 10.0
(2) Surface-treated zinc oxide powder of Example 3-5 10.0
(3) Isocetyl octanoate 5.0
(4) Decamethylcyclopentasiloxane 26.8
(5) Dimethylpolysiloxane 10.0
(6) POE-modified dimethylpolysiloxane 2.0
(7) Ion exchange water 28.0
(8) 1,3-butylene glycol 8.0
(9) Preservative 0.1
(10) Fragrance 0.1
(Manufacturing method) (3)-(6) was heat-mixed at 70 degreeC, and it was set as the oil phase. Separately, (8) and (9) were dissolved in (7) to make an aqueous phase. The powders (1) and (2) were added to the oil phase and dispersed with a homomixer. The previous aqueous phase was added to this and emulsified with a homomixer. Further, (10) was mixed and filled into a container.
The two-layer type W / O sunscreen obtained as described above was excellent in makeup retention and could be easily washed away with water using soap.

It is a photograph figure of pH5 buffer solution of MAD homopolymer / unprocessed zinc oxide powder, and pH10 buffer solution. Example 1-1 (MAD homopolymer / carboxyl modified silicone / zinc oxide powder) according to the present invention, Comparative example 1-1 (untreated zinc oxide powder), and Comparative example 1-2 (hydrophobized zinc oxide) 2 is a photograph of pH 5 buffer solution and pH 10 buffer solution of various powders.

Claims (8)

On the surface of the zinc oxide based powder treated so that the zinc ion elution amount measured by the following test method 1 is 30 ppm or less, the monomer (A) represented by the following general formula (1) is further used as a constituent monomer. A surface-treated zinc oxide powder, which is coated with a polymer to be contained.
[Test Method 1]
The zinc oxide powder is dispersed in water so as to be 0.01% by mass, and the pH of the dispersion is adjusted to maintain 7.5. The dispersion is centrifuged, and the zinc ion concentration (ppm) is measured for the supernatant after separation to obtain the zinc ion elution amount.

(In the formula, R ¹ is hydrogen or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 4 to 22 carbon atoms, X ¹ is an —NH— group or an oxygen atom, M ¹ is hydrogen or a monovalent inorganic group. Or represents an organic cation.)   2. The surface-treated zinc oxide powder according to claim 1, wherein the zinc oxide-based powder is a zinc oxide powder treated so that the zinc ion elution amount is 22 ppm or less. 3. body.   The surface-treated zinc oxide powder according to claim 1 or 2, wherein the zinc oxide-based powder is a zinc oxide powder treated with carboxyl-modified silicone.   The surface-treated zinc oxide powder according to claim 3, wherein the carboxyl-modified silicone is a carboxyl-modified silicone having a COOH equivalent of 500 to 5000 g / mol.   5. The surface-treated zinc oxide powder according to claim 1, wherein the polymer is a polymer containing 70% by mole or more of the monomer (A) in the total amount of the constituent monomers. body. The surface-treated oxidation oxide according to any one of claims 1 to 5, wherein the polymer further contains a monomer (B) represented by the following general formula (2) as a constituent monomer. Zinc powder.

(Wherein R ³ is hydrogen or an alkyl group having 1 to 3 carbon atoms, R ⁴ is an alkylene group having 1 to ⁴ carbon atoms, X ² is an —NH— group or an oxygen atom, and M ² is hydrogen or a monovalent inorganic group. Or represents an organic cation.)   The surface-treated zinc oxide powder according to any one of claims 1 to 6, wherein a coating amount of the polymer with respect to the zinc oxide-based powder is a mass ratio of polymer: powder = 3: 97 to 40:60. A surface-treated zinc oxide powder characterized by that.   A cosmetic comprising the surface-treated zinc oxide powder according to any one of claims 1 to 7.

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