JP2007039360A - Skin cosmetic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a skin cosmetic which gives an excellent sense of use having both freshness and body, has an excellent effect for imparting flexibility to the skins, and has extremely excellent temporal stability. <P>SOLUTION: This skin cosmetic is characterized by containing (a) a thickener comprising a micro gel obtained by dissolving a water-soluble ethylenic unsaturated monomer in a disperse phase and then radically polymerizing the monomer in the disperse phase, in a composition comprising an organic solvent or an oil as a dispersing medium and water as the disperse phase, and (b) an ester of hydrogenated castor oil with a higher fatty acid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a skin cosmetic. More specifically, the present invention relates to a skin cosmetic that has an excellent feeling of use with both freshness and richness, is excellent in flexibility imparting effect to the skin, has a moisturizing effect, and is extremely excellent in stability over time.

  Water-soluble thickeners that can be used in skin cosmetics include various polysaccharides, natural polymers such as gelatin, synthetic polymers such as polyoxyethylene and crosslinked poly (meth) acrylic acid, and inorganic minerals such as montmorillonite and silica. Etc.

  Among these, cross-linked poly (meth) acrylic acid is particularly inexpensive and has a high thickening effect and gels in a small amount. Therefore, it is frequently used as a water-soluble thickener or stabilizer in the cosmetic industry, especially skin cosmetics. Has been.

  However, cross-linked poly (meth) acrylic acid, which is widely used as a thickener, is capable of suppressing the dissociation of carboxyl groups under acidic conditions of pH 5 or lower or in an aqueous solution containing salts, resulting in extremely low viscosity and no gelation. . For this reason, it cannot be used in a formulation that requires acidic conditions and a salt coexistence system.

  Specifically, the most widely used thickener for cosmetics at present is a polymer of acrylic acid generically called carboxyvinyl polymer, and trade names are Hibiswako (Wako Pure Chemical Industries, Ltd.) (3V SIGMA), Carbopol (Goodrich), etc. These thickeners are chemically cross-linked polymers (The B.F. Goodrich Company, Specialty Polymers and Chemical Div., Carbopol Data Sheets and Applications Literature).

Such an aqueous dispersion of a crosslinked polymer has a very high thickening effect and is widely used as a thickener for cosmetics (see, for example, Patent Document 1).
However, as a disadvantage of these carboxyvinyl polymers, there is a problem that the pH range in which the viscosity can be increased is limited. In the carboxyvinyl polymer, the polymer swells and thickens in water when the carboxyl group contained in the polymer is in a dissociated state. Therefore, the carboxyvinyl polymer does not function as a thickener in the pH range below weak acidity where the carboxyl group is not sufficiently dissociated, and the development of a thickener capable of thickening over a wide pH range is an alternative. Is strongly desired.

  In order to solve this problem, a copolymer of acrylamide alkyl sulfonic acid and (meth) acrylic acid (Patent Document 2), a copolymer of acrylamide alkyl sulfonic acid and an alkyl group-containing unsaturated monomer (Patent Document) 3) A homopolymer of 2-acrylamido-2-methylpropanesulfonic acid (Patent Document 4) or polyacrylic acid amide has been applied to cosmetics.

JP-A-8-99855 JP-A-9-157130 JP-A-10-279636 JP-A-10-67640

  However, although the polymer having an acrylamide alkyl sulfonic acid in the above skeleton has improved acid resistance and can be used in a formulation requiring acidic conditions, a sticky feeling at the time of drying, which is considered to be derived from acrylic acid, occurs, and the thickening makeup It cannot be said that it has reached usability that is sufficiently satisfactory as a charge. Moreover, a phenomenon such as thickening or thinning due to gelation or the like is observed under low temperature storage, high temperature storage, or temperature change cycle storage, and it cannot be said that the stability over time is excellent. The same applies to the temporal stability of polyacrylic acid amide.

  On the other hand, technologies for blending various solid oils, semi-solid oils, and water hydrated oils into skin cosmetics are used for the purpose of giving a rich feeling when applied to the skin and imparting flexibility to the skin. ing. However, when solid oil, semi-solid oil, and water-holding oil are blended, a moist and rich feeling at the time of application can be obtained, but it is extremely difficult to satisfy a fresh feeling at the same time. Further, the stability over time may be deteriorated due to aggregation or coalescence of emulsion droplets, crystal precipitation, or the like.

  As a result of intensive studies in view of the above circumstances, the present inventors have used a microgel composed of a synthetic polymer electrolyte produced by a specific reverse phase emulsion polymerization (reverse phase microemulsion polymerization) as a cosmetic thickener, By blending hardened castor oil and higher fatty acid esters, it has an excellent feeling of use that has both freshness and richness, has an excellent effect of imparting flexibility to the skin, and has excellent stability over time. Has been found, and the present invention has been completed.

That is, the present invention
(A) A composition comprising an organic solvent or oil as a dispersion medium and water as a dispersion phase, comprising a microgel obtained by dissolving a water-soluble ethylenically unsaturated monomer in the dispersion phase and radical polymerization in the dispersion phase. A thickener,
(B) To provide a skin cosmetic characterized by containing hydrogenated castor oil and an ester of a higher fatty acid.

（Ｒ₁はＨまたはメチル基、Ｒ₂及びＲ₃はそれぞれ独立にメチル基、エチル基、プロピル基、イソプロピル基を表わす。） Moreover, this invention provides said skin cosmetics whose said water-soluble ethylenically unsaturated monomer is the dialkyl acrylamide shown by General formula (1), and an ionic acrylamide derivative.
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

（Ｒ₁はＨまたはメチル基、Ｒ₂及びＲ₃はそれぞれ独立にメチル基、エチル基、プロピル基、イソプロピル基を表わす。）

一般式（２）

（Ｒ₄及びＲ₅はそれぞれ独立にＨ又はメチル基、Ｒ₆は炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｘは金属イオン若しくはＮＨ₃を表わす。） Furthermore, the present invention provides the above skin cosmetic, wherein the water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1) and an anionic acrylamide derivative represented by the general formula (2). To do.



General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (2)

(R ₄ and R ₅ each independently represent H or a methyl group, R ₆ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and X represents a metal ion or NH _3. )

（Ｒ₁はＨまたはメチル基、Ｒ₂及びＲ₃はそれぞれ独立にメチル基、エチル基、プロピル基、イソプロピル基を表わす。）

一般式（３）

（Ｒ₇はＨ又はメチル基、Ｒ₈はＨまたは炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｒ₉は炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｒ₁₀、Ｒ₁₁、Ｒ₁₂はメチル基またはエチル基、Ｙは金属イオンを表わす。） The present invention also provides the above skin cosmetic, wherein the water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1) and a cationic acrylamide derivative represented by the general formula (3). To do.
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (3)

(R ₇ is H or a methyl group, R ₈ is H or a linear or branched alkyl group having 1 to 6 carbon atoms, R ₉ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ₁₀ , R ₁₁ and R ₁₂ represent a methyl group or an ethyl group, and Y represents a metal ion.)

（Ｒ₁はＨまたはメチル基、Ｒ₂及びＲ₃はそれぞれ独立にメチル基、エチル基、プロピル基、イソプロピル基を表わす。）

一般式（２）

（Ｒ₄及びＲ₅はそれぞれ独立にＨ又はメチル基、Ｒ₆は炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｘは金属イオン若しくはＮＨ₃を表わす。）

一般式（４）

Further, in the present invention, the water-soluble ethylenically unsaturated monomer is represented by the dialkylacrylamide represented by the general formula (1), the anionic acrylamide derivative represented by the general formula (2), and the general formula (4). The above-mentioned skin cosmetic which is a crosslinkable monomer is provided.
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (2)

(R ₄ and R ₅ each independently represent H or a methyl group, R ₆ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and X represents a metal ion or NH _3. )

General formula (4)

（Ｒ₁はＨまたはメチル基、Ｒ₂及びＲ₃はそれぞれ独立にメチル基、エチル基、プロピル基、イソプロピル基を表わす。）

一般式（３）

（Ｒ₇はＨ又はメチル基、Ｒ₈はＨまたは炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｒ₉は炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｒ₁₀、Ｒ₁₁、Ｒ₁₂はメチル基またはエチル基、Ｙは金属イオンを表わす。）

一般式（４）

In the present invention, the water-soluble ethylenically unsaturated monomer includes a dialkylacrylamide represented by the general formula (1), a cationic acrylamide derivative represented by the general formula (3), and a crosslinking represented by the general formula (4). The above-mentioned skin cosmetic composition, which is a sex monomer, is provided.


General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (3)

(R ₇ is H or a methyl group, R ₈ is H or a linear or branched alkyl group having 1 to 6 carbon atoms, R ₉ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ₁₀ , R ₁₁ and R ₁₂ represent a methyl group or an ethyl group, and Y represents a metal ion.)

General formula (4)

  Further, the present invention provides the above skin cosmetic, wherein the ester of (b) hydrogenated castor oil and a higher fatty acid is a monoester of hydrogenated castor oil and a higher fatty acid having 14 to 22 carbon atoms. It is to provide.

  In the present invention, the blending amount of the thickener (a) is 0.01 to 2.5% by mass with respect to the total amount of the skin cosmetic, and the blending amount of the ester (b) is the skin cosmetic. The present invention provides the above-described skin cosmetic, which is 0.01 to 5.0% by mass with respect to the total amount.

  In addition, the present invention further provides (c) an HLB 3-18 nonionic surfactant, wherein the skin cosmetic is an oil-in-water emulsified composition. It is.

(1) It has an excellent feeling of use having both freshness and richness.
(2) Excellent skin softening and moisturizing effects.
(3) Extremely excellent stability over time.

  Hereinafter, the present invention will be described in detail.

  The essential component of the present invention, “(a) thickener composed of microgel” is a composition having an organic solvent or oil as a dispersion medium and water as a dispersed phase, and a water-soluble ethylenically unsaturated monomer as a dispersed phase. It is a thickener made of a microgel of a synthetic polymer obtained by radical polymerization in a dispersed phase. That is, a polymer microgel produced by a polymerization method generally referred to as a reverse emulsion polymerization method is used for the use of a thickener, and uniform polymerization as disclosed in JP-A-2001-114641. The polymerization method and mechanical properties are different from the thickener made of a synthetic polymer obtained by the system.

  A microgel is a fine particle of a synthetic polymer electrolyte produced by a reverse phase microemulsion polymerization method. The thickener made of microgel used in the present invention swells in water, ethanol or a water-ethanol mixed solution, and can provide a high viscosity solution which is visually uniform in appearance.

The microgel polymerization system used as the thickener used in the present invention is different from the homogeneous polymerization system for producing a synthetic polymer which is a conventional thickener. For example, the synthetic polymer based on the homogeneous polymerization system disclosed in Japanese Patent Application Laid-Open No. 2001-114641 is not a microgel used in the present invention, but after the synthetic polymer is polymerized, it is pulverized into a powder state for blending into cosmetics. There must be. In addition, a synthetic polymer gel is noticeable and may cause problems in appearance.
In contrast, the microgel used in the present invention is polymerized in a heterogeneous polymerization system. The resulting synthetic polymer becomes a fine polymer gel, that is, a microgel, and when blended into cosmetics, it does not need to be pulverized and powdered, exhibits an excellent thickening effect and excellent usability. Furthermore, the appearance of the cosmetic is also preferable.

  In addition, regarding the reverse phase emulsion polymerization method of a polymer, there is a description of a technology in which a water-swellable polymer using acrylic acid is produced by reverse phase polymerization in Patent No. 1911623 and applied as a thickener. This is different from the microgel used in the present invention in order to improve the drawbacks of carboxyvinyl polymers currently in wide use.

  Japanese Patent Application Laid-Open No. 9-12613 discloses that water-absorbent resin microgel particles are produced in a certain size or more so as to be suitable for a diaper or a sanitary product. It is not a technique that can be applied to the agent, and is completely different from the microgel used in the present invention.

The thickener used in the present invention is produced by a reverse phase emulsion polymerization method. That is, in a composition having an organic solvent or an oil as a dispersion medium and water as a dispersed phase, it is produced by dissolving a water-soluble ethylenically unsaturated monomer in the dispersed phase and radical polymerization in the dispersed phase. The polymerized microgel is washed and dried, but need not be crushed.
In particular, by using a surfactant adjusted to an appropriately selected hydrophilic / hydrophobic balance (HLB), the microgel under the condition that the polymerization system in the inverse emulsion polymerization forms a one-phase microemulsion or a fine W / O emulsion. It is preferred that a thickener consisting of

  A single-phase microemulsion is a state in which the oil phase and the water phase coexist thermodynamically and the interfacial tension between the oil and water is minimized. The fine W / O emulsion is thermodynamically unstable, but oil and water are present as fine W / O emulsions stably in kinetics. Generally, the particle diameter of the inner aqueous phase of the fine W / O emulsion is about several tens to 100 nm. These states are determined only by the composition and temperature of the system and do not depend on mechanical stirring conditions.

The composition constituting the polymerization system is composed of an organic solvent or oil that does not mix with water (dispersing medium constituting the outer phase) and a dispersed phase consisting of water (constituting the inner phase).
Preferable organic solvents include alkanes such as pentane, hexane, heptane, octane, nonane, decane, undecane; cycloalkanes such as cyclopentane, cyclohexane, cycloheptane, cyclooctane; benzene, toluene, xylene, decalin, naphthalene, etc. And aromatic and cyclic hydrocarbons.
Preferred oils include nonpolar oils such as paraffin oil.

  The water-soluble ethylenically unsaturated monomer is dissolved in water as a dispersed phase, then mixed with an organic solvent or oil as a dispersion medium, heated to a desired temperature, and then a polymerization initiator is added to the aqueous phase for polymerization. .

  In general, in the heterogeneous polymerization method, it is known that the properties of the polymer produced vary depending on the stirring conditions during the polymerization. The reason is that since the emulsification system is not thermodynamically stable, the shape and size of the emulsified particles change depending on the stirring conditions. In the present invention, it has been found that these problems can be avoided by performing polymerization in a thermodynamically stable one-phase microemulsion region or a fine W / O emulsion region that exists in the vicinity of a metastable one-phase region. It was. Specifically, the composition of the polymerization system (type of organic solvent, so that the above-mentioned one-phase microemulsion or fine W / O emulsion region appears in the vicinity of the optimum polymerization temperature of the polymerization initiator for normal thermal polymerization or redox polymerization. By adjusting the surfactant (HLB), it became possible to obtain a microgel with a high thickening effect by polymerizing the polymer in a fine aqueous phase (water droplets).

  In contrast, conventional polymer thickeners by suspension polymerization (for example, the method described in JP-A-2001-1146641) are difficult to control the particle size of water droplets during polymerization, and thus a good quality microgel can be obtained. It is difficult.

The water-soluble ethylenically unsaturated monomer is preferably a combination of a nonionic monomer and an ionic monomer (anionic monomer or cationic monomer).
The nonionic monomer is preferably a dialkylacrylamide represented by the general formula (1).
The ionic monomer is preferably an anionic acrylamide derivative represented by the general formula (2) or a cationic acrylamide derivative represented by the general formula (3).

（Ｒ₄及びＲ₅はそれぞれ独立にＨ又はメチル基、Ｒ₆は炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｘは金属イオン、ＮＨ_3、アミン化合物を表す。例えば、金属イオンはLi、Na、Kのアルカリ金属イオン、アミン化合物はトリエタノールアミン、トリイソプロパノールアミン等である。）

一般式（３）

（Ｒ₇はＨ又はメチル基、Ｒ₈はＨまたは炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｒ₉は炭素原子数１〜６の直鎖若しくは分岐のアルキル基、Ｒ₁₀、Ｒ₁₁、Ｒ₁₂はメチル基またはエチル基、Ｙは陰性カウンターイオンを表わし、例えば、Cl、Bｒ等のマイナスカウンターイオンである。） General formula (2)

(R ₄ and R ₅ are each independently H or a methyl group, R ₆ is a linear or branched alkyl group having 1 to 6 carbon atoms, X is a metal ion, NH _{3, or an} amine compound. For example, a metal ion Are Li, Na, K alkali metal ions, and amine compounds are triethanolamine, triisopropanolamine, etc.)

General formula (3)

(R ₇ is H or a methyl group, R ₈ is H or a linear or branched alkyl group having 1 to 6 carbon atoms, R ₉ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ₁₀ , R ₁₁ and R ₁₂ are a methyl group or an ethyl group, and Y represents a negative counter ion, for example, a negative counter ion such as Cl or Br.)

Particularly preferred dialkylacrylamides are dimethylacrylamide and diethylacrylamide.
Particularly preferred ionic acrylamide derivatives are 2-acrylamide 2-methylpropanesulfonic acid and its salts.
A particularly preferred cationic acrylamide derivative is N, N, -dimethylaminopropylacrylamide methyl chloride.

  The monomer composition ratio in the polymerization system of the nonionic monomer and the ionic monomer (the charge ratio of the polymerization system) is arbitrarily determined arbitrarily according to the monomer composition ratio of the target microgel. The monomer composition ratio of the microgel and the charging ratio to the polymerization system are almost the same. The charging ratio (molar ratio) of the polymerization system of the nonionic monomer and the ionic monomer is usually nonionic monomer: ionic monomer = 0.5: 9.5 to 9.5: 0.5, preferably 1. : 9 to 9: 1, more preferably 7: 3 to 9: 1. The optimum ratio is nonionic monomer: ionic monomer = 8: 2.

  The above-mentioned water-soluble ethylenically unsaturated monomer is arbitrarily selected to polymerize the thickener of the present invention. A particularly preferred thickener is a binary copolymer microgel copolymerized from dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid as water-soluble ethylenically unsaturated monomers. In this case, there is no need for a crosslinking monomer, and a thickener that exhibits an excellent thickening effect and a feeling of use due to self-crosslinking can be obtained.

A crosslinking monomer can also be used. In that case, the crosslinking monomer represented by the general formula (4) is preferable, and methylenebisacrylamide is particularly preferable.









General formula (4)

  In order to dissolve the water-soluble ethylenically unsaturated monomer in the dispersed phase and polymerize the preferred microgel for the present invention, it is necessary to select the optimum outer phase oil or organic solvent and surfactant. . The present inventor prepared a polymerization system to show a cloud point at a temperature suitable for thermal radical polymerization by creating a phase diagram of the hydrophilic-hydrophobic balance (HLB) of the nonionic surfactant in the composition of the polymerization system. Thus, it was found that a microgel having a rheological characteristic preferable as a thickener can be obtained by creating a state of forming a one-phase microemulsion or a fine W / O emulsion at a normal thermal radical polymerization temperature.

Preferred surfactants are polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene hexyl decyl ether, polyoxyethylene isostearyl ether , Polyoxyethylene octyldodecyl ether, polyoxyethylene behenyl ether, polyoxyethylene cholesteryl ether, polyoxyethylene hydrogenated castor oil, sorbitan fatty acid ester, mono fatty acid glycerin, tri fatty acid glycerin, polyglycerin fatty acid ester, isostearic acid polyoxyethylene glycerin, Polyoxyethylene glycerin triisostearate, polyoxymonostearate Ji Ren glycerin distearate, polyoxyethylene glyceryl, and the like tristearate polyoxyethylene glyceryl.
These surfactants can be appropriately combined to adjust to a desired HLB and added to the polymerization system.

  In addition, in the microgel copolymerized with dialkylacrylamide and acrylamide-based ionic monomer, spontaneous crosslinking reaction proceeds, and it is chemically self-crosslinking without the need to copolymerize polyfunctional crosslinking monomer as the third component. The resulting microgel is obtained and is a particularly preferred thickener for use in the present invention.

  Although the third component polyfunctional crosslinking monomer is not necessary, the microgel used in the present invention can be synthesized even if it is added and copolymerized. The multifunctional crosslinking monomer is preferably a monomer represented by the general formula (4), and can be crosslinked using one or more kinds of crosslinking monomers represented by the general formula (4). It is essential that these crosslinkable monomers can take a crosslinked structure efficiently in a polymerization system of dialkylacrylamide and an ionic acrylamide derivative.

  Preferred crosslinkable monomers include, for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyoxyethylene diacrylate, polyoxyethylene dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, N, N′-methylenebisacrylamide, N, N′-ethylenebisacrylamide, triallyl isocyanurate, pentaerythritol dimethacrylate, and the like can be used, and one or more selected from these can be used. In the present invention, N, N′-methylenebisacrylamide is particularly preferably used.

  The molar ratio of the content of 2-acrylamido-2-methylpropanesulfonic acid unit and dialkylacrylamide unit in the copolymer that is a thickener used in the present invention is usually 2-acrylamido-2-methylpropanesulfonic acid. Unit: dialkylacrylamide unit = 0.5: 9.5 to 9.5: 0.5, preferably 1: 9 to 9: 1, and more preferably = 3: 7 to 1: 9. The optimum ratio is 2-acrylamido-2-methylpropanesulfonic acid unit: dialkylacrylamide unit = 2: 8. The viscosity of the thickener of the present invention is due to molecular chain extension due to electrostatic repulsion based on a sulfonyl group, which is a strong dissociation group, and spontaneous crosslinking reaction of dialkylacrylamide or a crosslinked structure with a crosslinking monomer. -When the content of the acrylamide-2-methylpropanesulfonic acid unit or a salt thereof is less than 5 mol% with respect to the dialkylacrylamide unit, the molecular chain may not be sufficiently stretched, so that sufficient viscosity may not be obtained.

  The use amount of the crosslinkable monomer is preferably in the range of 0.0001 to 2.0 mol% with respect to the total number of moles of 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof and dialkylacrylamide. Thickeners prepared at less than 0.0001 mol% may not have a crosslinking effect. Moreover, when it exceeds 2 mol%, since a crosslinking density is too high and a microgel cannot fully swell, it may not exhibit sufficient thickening effect.

  The molecular weight of the microgel used in the present invention is about 100,000 to 5,000,000 (average in terms of PEG: measured by GPC), and is adjusted by the viscosity required as a thickener.

The microgel obtained by the above polymerization method has all the rheological properties of the following (1) to (3). The thickener composed of the microgel is obtained by the production method by the polymerization method described above, and is preferably used as a thickener.
(1) The apparent viscosity of an aqueous dispersion of 0.5% (mass percentage) of the microgel is 10,000 mPa · s or more at a shear rate of 1.0 s ⁻¹ .
(2) The apparent viscosity of the 0.5% (percentage by mass) ethanol dispersion of the microgel is 5000 mPa · s or more at a shear rate of 1.0 s ⁻¹ .
(3) The dynamic elastic modulus in a 0.5% (mass percentage) aqueous dispersion or ethanol dispersion of the microgel is G ′> G ″ within a strain of 1% or less and a frequency of 0.01 to 10 Hz.
The apparent viscosity of the water or ethanol dispersion of the microgel is a viscosity at a measurement temperature of 25 ° C. and a shear rate of 1 s ⁻¹ using a cone plate rheometer (MCR-300 manufactured by Paar Rhysica).
The dynamic elastic modulus is the value of the storage elastic modulus (G ') and loss elastic modulus (G ") measured at a measurement temperature of 25 ° C and a strain of 1% or less in the frequency range of 0.1 to 10 Hz using the same measuring device. Means.

The microgel used in the present invention can be separated in a powder state through a simple precipitation purification step after polymerization. The microgel separated into a powder form easily disperses in water or ethanol or a mixed solvent of water / ethanol, swells quickly, and functions as a thickener.
In addition, by selecting a strongly acidic monomer (for example, a monomer containing a sulfonic acid residue) as an ionic monomer to be copolymerized with the microgel, an acidic preparation that cannot be thickened with a conventional carboxyvinyl polymer can be obtained. Thickening is also possible.

  The skin cosmetic of the present invention is produced by blending the above-mentioned microgel into a skin cosmetic base as a thickener. The blending amount of the thickener is appropriately determined according to the intended cosmetic and is not limited. From the viewpoint of usability, a preferable blending amount is 0.01 to 2.5% by mass, and more preferably 0.05 to 1.5% by mass. If it exceeds 2.5% by mass, a problem may occur in terms of stickiness or freshness. On the other hand, if it is less than 0.01% by mass, a sufficient thickening effect may not be obtained.

Next, "(b) hardened castor oil and higher fatty acid ester" which is another essential component of the present invention will be described in detail.
(B) Hardened castor oil and higher fatty acid ester are compounds obtained by esterifying a part or all of hydroxyl groups of hardened castor oil obtained by hydrogenating castor oil with other higher fatty acids. Specifically, monostearic acid hydrogenated castor oil, monoisostearic acid hydrogenated castor oil, monohydroxystearic acid hydrogenated castor oil, triisostearic acid hydrogenated castor oil and the like are exemplified.

In the present invention, the component (b) can give a rich feeling when applied to the skin, impart flexibility to the skin, and enhance the moisturizing effect. The component (b) is not particularly limited as long as it is an ester of hydrogenated castor oil and higher fatty acid, which can be usually used in cosmetics, but is preferably a monoester of hydrogenated castor oil and a higher fatty acid having 14 to 22 carbon atoms. Monostearic acid hydrogenated castor oil, monoisostearic acid hydrogenated castor oil, monohydroxystearic acid hydrogenated castor oil and the like are preferable. Among these, monostearic acid hydrogenated castor oil represented by the following formula (5) is particularly preferable in the present invention.
Formula (5)

  Component (b) hydrogenated castor oil and higher fatty acid ester can be used singly or in combination of two or more, and the blending amount is preferably 0.01 to 5.0% by mass relative to the total amount of skin cosmetics. More preferably, it is 0.1-3.0 mass%. If it is less than 0.01% by mass, the effect of the blending is not exhibited, and if it exceeds 5.0% by mass, stickiness may occur.

In the skin cosmetic of the present invention, it is also preferable to emulsify the oil using an emulsifier and blend it in the composition to obtain an oil-in-water emulsion skin cosmetic. Examples of oils that can be used include hydrocarbon oils, silicone oils, waxes, fatty acid esters, higher alcohols, and UV absorbers.
Examples of the hydrocarbon oil include liquid paraffin, ozokerite, squalane, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, polyethylene wax, and Fischer-Tropsch wax.
Examples of the silicone oil include linear polysiloxanes (for example, dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, etc.); cyclic polysiloxanes (for example, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, etc.), 3 Silicone resin forming a three-dimensional network structure, silicone rubber having an average molecular weight of 200,000 or more, various modified polysiloxanes (amino-modified polysiloxane, polyether-modified polysiloxane, alkyl-modified polysiloxane, fluorine-modified polysiloxane, etc.) It is done.
Examples of the waxes include beeswax, candelilla wax, carnauba wax, lanolin, liquid lanolin, jojoballow and the like.
Examples of the fatty acid ester include myristyl myristate, cetyl palmitate, cholesteryl stearate, beeswax fatty acid 2-octyldodecyl and the like.
Examples of the higher alcohol include hexyl alcohol, octyl alcohol, cetyl alcohol, stearyl alcohol, ceryl alcohol, behenyl alcohol, triacontyl alcohol, seraalkyl alcohol, and batyl alcohol.
Examples of ultraviolet absorbers include paraaminobenzoic acid, octyl-p-methoxycinnamate (2-ethylhexyl-p-methoxycinnamate), glyceryl mono-2-ethylhexanoyl-diparamethoxycinnamate, trimethoxycinnamate Cinnamic acid UV absorbers such as methylbis (trimethylsiloxane) silylisopentyl acid, 2,2'-hydroxy-5-methylphenylbenzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzo Triazole, 2- (2′-hydroxy-5′-methylphenylbenzotriazole, 4-methoxy-4′-tert-butyldibenzoylmethane, 5- (3,3-dimethyl-2-norbornylidene) -3-pentane- 2-one, bis-ethylhexyloxyphenol-methoxyphenyl Triazine, 2,4,6-tris [4- (2-ethylhexyloxycarbonyl) anilino] 1,3,5-triazine, dimorpholino pyridazinone like.

Moreover, as an emulsifier used for this invention, what uses the nonionic surfactant of HLB3-18 is more preferable from a fresh use feeling and stability viewpoint.
Specific examples of HLB 3-18 nonionic surfactants are given below. One kind or two or more kinds can be blended. However, it is not limited to these.

  POE (2) stearyl ether (HLB4.0), self-emulsifying propylene glycol monostearate (HLB4.0), glyceryl myristate (HLB3.5), glyceryl monostearate (HLB4.0), self-emulsifying monostearin Glyceryl acid (HLB4.0), glyceryl monoisostearate (HLB4.0), decaglyceryl pentastearate (HLB3.5), decaglyceryl pentaisostearate (HLB3.5), decaglyceryl pentaoleate (HLB3.5) , Monostearate sorbitan (HLB4.7), sorbitan monoisostearate (HLB5.0), sorbitan sesquiisostearate (HLB4.5), sorbitan monooleate (HLB4.3), hexastearic acid POE (6) sol (HLB3.0), POE (3) castor oil (HLB3.0), PEG monostearate (2) (HLB4.0), ethylene glycol monostearate (HLB3.5), PEG stearate (2) (HLB4.5), hexaglyceryl monolaurate (HLB14.5), hexaglyceryl monomyristate (HLB11), hexaglyceryl monostearate (HLB9.0), hexaglyceryl monooleate (HLB9.0), decamonolaurate Glyceryl (HLB15.5), decaglyceryl monomyristate (HLB14.0), decaglyceryl monostearate (HLB12.0), decaglyceryl monoisostearate (HLB12.0), decaglyceryl monooleate (HLB12.0) , Distearic acid deca Riseriru (HLB9,5), polyglycerol fatty acid esters such as diisostearate decaglyceryl (HLB10.0).

Polyoxyethylene monostearate (hereinafter abbreviated as POE) (5) Glyceryl (HLB9.5), POE (15) monostearate (HLB13.5), POE monooleate (5) glyceryl (HLB9.5) Polyoxyethylene glycerin fatty acid esters such as monooleic acid POE (15) glyceryl (HLB14.5).
Mono palm oil fatty acid POE (20) sorbitan (HLB16.9), monopalmitic acid POE (20) sorbitan (HLB15.6), monostearic acid POE (20) sorbitan (HLB14.9), monostearic acid POE (6) sorbitan (HLB9.5), tristearic acid POE (20) sorbitan (HLB10.5), monoisostearic acid POE (20) sorbitan (HLB15.0), monooleic acid POE (20) sorbitan (HLB15.0), monoolein Polyoxyethylene sorbitan fatty acid esters such as acid POE (6) sorbitan (HLB 10.0) and trioleic acid POE (20) sorbitan (HLB 11.0).

  Monolauric acid POE (6) sorbitol (HLB15.5), tetrastearic acid POE (60) sorbitol (HLB13.0), tetraoleic acid POE (30) sorbitol (HLB11.5), tetraoleic acid POE (40) sorbitol ( Polyoxyethylene sorbite fatty acid esters such as HLB 12.5) and tetraoleic acid POE (60) sorbite (HLB14.0).

  POE (10) lanolin (HLB12.0), POE (20) lanolin (HLB13.0), POE (30) lanolin (HLB15.0), POE (5) lanolin alcohol (HLB12.5), POE (10) lanolin Polyoxyethylene lanolin and lanolin such as alcohol (HLB15.5), POE (20) lanolin alcohol (HLB16.0), POE (40) lanolin alcohol (HLB17.0), POE (20) sorbit beeswax (HLB9.5) Alcohol and beeswax derivatives.

  POE (20) castor oil (HLB10.5), POE (40) castor oil (HLB12.5), POE (50) castor oil (HLB14.0), POE (60) castor oil (HLB14.0), POE ( 20) hydrogenated castor oil (HLB10.5), POE (30) hydrogenated castor oil (HLB11.0), POE (40) hydrogenated castor oil (HLB13.5), POE (60) hydrogenated castor oil (HLB14.0), Polyoxyethylene castor oil and hydrogenated castor oil such as POE (80) hydrogenated castor oil (HLB16.5) and POE (40) hydrogenated castor oil (100) hydrogenated castor oil (HLB16.5).

  POE (5) phytosterol (HLB9.5), POE (10) phytosterol (HLB12.5), POE (20) phytosterol (HLB15.5), POE (30) phytosterol (HLB18.0), POE (25) phytostanol Polyoxyethylene sterols and hydrogenated sterols such as (HLB14.5) and POE (30) cholestanol (HLB17.0).

POE (2) lauryl ether (HLB9.5), POE (4.2) lauryl ether (HLB11.5), POE (9) lauryl ether (HLB14.5), POE (5.5) cetyl ether (HLB10.5) ), POE (7) cetyl ether (HLB11.5), POE (10) cetyl ether (HLB13.5), POE (15) cetyl ether (HLB15.5), POE (20) cetyl ether (HLB17.0), POE (23) cetyl ether (HLB18.0), POE (4) stearyl ether (HLB9.0), POE (20) stearyl ether (HLB18.0), POE (7) oleyl ether (HLB10.5), POE ( 10) oleyl ether (HLB14.5), POE (15) oleyl ether (H B16.0), POE (20) oleyl ether (HLB17.0), POE (50) oleyl ether (HLB18.0), POE (10) behenyl ether (HLB10.0), POE (20) behenyl ether (HLB16.B). 5), POE (30) behenyl ether (HLB18.0), POE (2) (C12-15) alkyl ether (HLB9.0), POE (4) (C12-15) alkyl ether (HLB10.5), POE (10) (C12-15) alkyl ether (HLB15.5), POE (5) secondary alkyl ether (HLB10.5), POE (7) secondary alkyl ether (HLB12.0), POE (9) alkyl ether (HLB13.5), POE (12) alkyl ether (HLB14.5), etc. Carboxymethyl ethylene alkyl ethers.

  Polyoxyethylene (hereinafter abbreviated as POE) (1) polyoxypropylene (hereinafter abbreviated as POP) (4) cetyl ether (HLB9.5), POE (10) POP (4) cetyl ether (HLB10.5), POE (20) POP (8) cetyl ether (HLB12.5), POE (20) POP (6) decyl tetradecyl ether (HLB 11.0), POE (30) POP (6) decyl tetradecyl ether (HLB 12.0) ) And other polyoxyethylene polyoxypropylene alkyl ethers.

  Polyethylene glycol monolaurate (hereinafter abbreviated as PEG) (10) (HLB12.5), PEG monostearate (10) (HLB11.0), PEG monostearate (25) (HLB15.0), PEG monostearate (40) (HLB17.5), PEG monostearate (45) (HLB18.0), PEG monostearate (55) (HLB18.0), PEG monooleate (10) (HLB11.0), distearic acid Polyethylene glycol fatty acid esters such as PEG (HLB16.5) and diisostearic acid PEG (HLB9.5).

  PEG (8) glyceryl isostearate (HLB10.0), PEG (10) glyceryl isostearate (HLB10.0), PEG (15) glyceryl isostearate (HLB12.0), PEG (20) glyceryl isostearate (HLB13.0) ), PEG (25) glyceryl isostearate (HLB14.0), PEG glyceryl isostearate (30) (HLB15.0), PEG (40) glyceryl isostearate (HLB15.0), PEG (50) glyceryl isostearate (HLB16) 0.0), polyoxyethylene glyceryl isostearates such as PEG (60) glyceryl isostearate (HLB 16.0).

  In the present invention, when the oil-in-water emulsion skin cosmetic is used, the nonionic surfactant of HLB 3-18 is preferably 5.0% by mass or less. This is because if it exceeds 5.0% by mass, a problem may occur in terms of usability such as freshness.

  In addition to the essential components described above, the skin cosmetic of the present invention can be produced by a conventional method by appropriately blending components that can be blended with a normal skin cosmetic within a range that does not impair the effects of the present invention. The component which can be mix | blended below is illustrated.

  Examples of the polyhydric alcohol include polyethylene glycol, glycerin, diglycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, maltitol, 1,2-pentanediol, hexylene glycol and the like.

  Examples of the water-soluble polymer include carrageenan, pectin, mannan, curdlan, chondroitin sulfate, starch, glycogen, gum arabic, sodium hyaluronate, tragacanth gum, xanthan gum, mucoitin sulfate, hydroxyethyl guar gum, carboxymethyl guar gum, guar gum, dextran. , Keratosulfuric acid, locust bean gum, succinoglucan, chitin, chitosan, carboxymethylchitin, agar and the like.

In addition, lower alcohols such as ethanol; antioxidants such as butylhydroxytoluene, δ-tocopherol and phytin; antiseptics such as benzoic acid, salicylic acid, sorbic acid, paraoxybenzoic acid alkyl esters, phenoxyethanol, hexachlorophene, and ε-polylysine; Organic or inorganic acids such as citric acid, lactic acid, hexametaphosphoric acid and their salts; vitamin A, vitamin A palmitate, vitamin A derivatives such as vitamin A acetate, vitamin B ₆ hydrochloride, vitamin B ₆ tripalmitate, vitamin B ₆ dioctanoate , vitamin B ₂ and derivatives thereof, vitamin B _12, vitamin B such as vitamin B ₁₅ and its derivatives, alpha-tocopherol, beta-tocopherol, vitamin E such as vitamin E acetate, vitamin D, vitamin H, Pantote Vitamins such as acid and pantethine; γ-oryzanol, allantoin, glycyrrhizic acid (salt), glycyrrhetinic acid, stearyl glycyrrhetinate, hinokitiol, bisabolol, eucarptone, thymol, inositol, saikosaponin, carrot saponin, hetimasaponin, muclodisaponin Saponins such as, pantothenyl ethyl ether, various drugs such as arbutin, cephalanthin, borage, clara, kohone, orange, sage, yarrow, mallow, thyme, thyme, spruce, birch, sugina, loofah, maronier, yukinoshita, Extracts of plants such as ougon, arnica, lily, mugwort, peonies, aloe, gardenia, cherry leaf, pigments such as β-carotene, and the like can also be blended.

  The dosage form of the skin cosmetic of the present invention is arbitrary, and any dosage form may be used. Further, the product form of the skin cosmetic of the present invention is also optional, such as facial skin cosmetics such as lotion, milky lotion, cream and pack; makeup cosmetics such as foundation, lipstick and eye shadow; body skin cosmetics; aromatic skin Can be used in cosmetics.

  The present invention will be described in further detail with reference to the following examples. The present invention is not limited in any way by the following examples. Unless otherwise specified, the amount is shown in mass%.

  First, a synthesis example of the microgel used in the present invention will be described. The microgel obtained in the synthesis example is a thickener used in the present invention.

Synthesis Example 1 Synthesis of Microgel “Poly (dimethylacrylamide-co-2-acrylamide-2-methylpropanesulfonic acid-co-methylenebisacrylamide)”
Dissolve 35 g of dimethylacrylamide (manufactured by Kojin), 17.5 g of 2-acrylamide-2-methylpropanesulfonic acid (manufactured by Sigma) and 7 mg of methylenebisacrylamide in 260 g of ion-exchanged water, and adjust the pH to 7.0 with sodium hydroxide. In a 1000 ml three-necked flask equipped with a reflux apparatus, 260 g of n-hexane, polyoxyethylene (3) oleyl ether (Emalex 503, manufactured by Nippon Emulsion) 8.7 g and epolyoxyethylene (6) oleyl ether (Emalex 506) , manufactured by Nippon emulsion) 17.6g were mixed and dissolved into the N ₂ to replace. An aqueous monomer solution is added to the three-necked flask and heated to 65 ° C. to 70 ° C. in an oil bath while stirring under an N ₂ atmosphere. After confirming that the system is in a translucent microemulsion state when the temperature of the system reaches 65 ° C. to 70 ° C., 2 g of ammonium persulfate is added to the polymerization system and polymerization is started. A microgel is formed by maintaining the polymerization system at 65-70 ° C. with stirring for 3 hours. After the polymerization is completed, acetone is added to the microgel suspension to precipitate the microgel, followed by washing with acetone three times to remove residual monomer and surfactant. The precipitate is filtered and dried under reduced pressure to obtain a dried white powdered microgel.

Synthesis Example 2 Synthesis of Microgel “Poly (dimethylacrylamide-co-N, N-dimethylaminopropylacrylamidemethyl chloride-co-methylenebisacrylamide)”
Dissolve 35 g of dimethylacrylamide (manufactured by Kojin), 17.5 g of N, N-dimethylaminopropylacrylamide methyl chloride (manufactured by Kojin) and 7 mg of methylenebisacrylamide in 260 g of ion-exchanged water. In a 1000 ml three-necked flask equipped with a reflux apparatus, 260 g of n-hexane, polyoxyethylene (3) oleyl ether (Emalex 503, manufactured by Nippon Emulsion) 8.7 g and polyoxyethylene (6) oleyl ether (Emalex 506, Japanese-made emulsion) 17.6g were mixed and dissolved into the N ₂ to replace. An aqueous monomer solution is added to the three-necked flask and heated to 65 ° C. to 70 ° C. in an oil bath while stirring under an N ₂ atmosphere. After confirming that the system is in a translucent microemulsion state when the temperature of the system reaches 65 ° C. to 70 ° C., 2 g of ammonium persulfate is added to the polymerization system and polymerization is started. A microgel is formed by maintaining the polymerization system at 65-70 ° C. with stirring for 3 hours. After the polymerization is completed, acetone is added to the microgel suspension to precipitate the microgel, followed by washing with acetone three times to remove residual monomer and surfactant. The precipitate is filtered and dried under reduced pressure to obtain a dried white powdered microgel.

  Skin care emulsions of Examples 1 to 10 and Comparative Examples 1 to 11 having the blended composition described in “Table 1” and “Table 2” were produced by a conventional method. The obtained emulsion (sample) was evaluated for stability and usability (longness, freshness, richness, stickiness, softening effect on skin) by the following test methods.

[Stability test]
The samples were stored for 1 month under low temperature 0 ° C. storage, high temperature 50 ° C. storage, and 5-45 ° C. cycle storage, and then the viscosity after 3 months storage was measured and judged according to the following evaluation criteria.
(Evaluation criteria)
○: No decrease or increase in viscosity was observed.
Δ: Slight decrease in viscosity or increase in 3 months
X: Viscosity decreased or increased in 1 month.
[Usability]
An actual use test was conducted by a panel dedicated to women (10 persons), and the skin extension was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: All 10 persons judged that the spread was light and smooth.
○: 7 to 9 persons judged that the spread was light and smooth.
Δ: 3 to 6 persons judged that the spread was light and smooth.
X: 0 to 2 persons were judged to be light and smooth.
[Usability (freshness)]
An actual use test was conducted by a panel dedicated to women (10 persons), and the freshness was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: All 10 people judged that there was freshness.
○: Seven to nine people determined that there was freshness.
(Triangle | delta): Three to six persons judged having freshness.
X: It was determined that 0 to 2 persons had freshness.
[Usability (Body feeling)]
An actual use test was conducted by a panel dedicated to women (10 persons), and the richness was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: All 10 persons judged to have a rich feeling.
○: Seven to nine people determined that there was a rich feeling.
(Triangle | delta): Three to six persons judged having a rich feeling.
X: It was determined that 0 to 2 persons had a rich feeling.
[Usability (stickiness)]
An actual use test was conducted by a panel dedicated to women (10 persons), and the stickiness was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: All 10 people judged that there was no stickiness and was moist.
○: Seven to nine people judged that there was no stickiness and was moist.
(Triangle | delta): Three to six persons judged that there was no stickiness and was moist.
X: It was determined that 0-2 persons had no stickiness and were moist.
[Usability (softening effect on skin: Does it feel soft after application)]
An actual use test was conducted by a panel dedicated to women (10 persons), and the flexible effects were evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: All 10 people judged that there was a flexible effect.
○: 7 to 9 persons judged to have a flexible effect.
(Triangle | delta): Three to six persons determined with the softening effect.
X: 0 to 2 persons determined to have a flexible effect.

＊１）商品名：ＳＩＭＵＬＧＥＬ ＥＧ（ＳＥＰＩＣ社製）
＊２）商品名：セピゲル５０１（ＳＥＰＩＣ社製）

* 1) Product name: SIMULGEL EG (SEPIC)
* 2) Product name: Sepigel 501 (SEPIC)

As is apparent from the results of “Table 1” and “Table 2”, it can be seen that the skin care emulsions of Examples 1 to 10 of the present invention have excellent stability and usability.
Other examples of the present invention will be shown below.

Example 11 Skin care cream (compounding ingredient)
(1) Ion exchange water Residual (2) Sodium hexametaphosphate 0.05
(3) Microgel of Synthesis Example 1 0.4
(4) (Acrylic acid / alkyl acrylate (C10-30)) copolymer 0.1
(5) Potassium hydroxide 0.15
(6) Polyethylene glycol 1500 4.0
(7) Glycerin 5.0
(8) 1,3-butylene glycol 10.0
(9) Phenoxyethanol 0.5
(10) Vaseline 4.0
(11) Squalane 2.0
(12) (hydroxystearic acid / stearic acid / rosin acid)
Dipentaerythrityl 0.1
(13) Pentaerythrityl tetraoctanoate 2.0
(14) Monostearic acid hydrogenated castor oil 0.8
(15) POE (20) sorbitan monostearate 1.0
<Production method>
(10) to (15) were uniformly mixed and dissolved at 70 ° C. (oil phase). On the other hand, (1) to (9) were uniformly mixed and dissolved at 70 ° C. (aqueous phase). The mixture was emulsified with a homomixer while gradually adding the oil phase to the aqueous phase maintained at 70 ° C. When the emulsification was completed, it was rapidly cooled to 40 ° C. or lower to obtain the intended skin care cream.
<Product properties>
The obtained skin care cream was evaluated in the same manner as in Examples 1 to 10. As a result, it was excellent in usability (usability evaluation, spread on the skin, stickiness, richness, freshness, and softening effect ◎) and stable. The property was also good (stability evaluation: ◯).

Example 12 Whitening Skin Care Emulsion (Compounding ingredients)
(1) Ion exchange water Residual (2) Sodium hydroxide 0.3
(3) Sodium citrate 0.1
(4) Microgel of Synthesis Example 2 0.3
(5) Methylparaben 0.2
(6) Dipropylene glycol 5.0
(7) Glycerin 3.0
(8) Ethanol 2.0
(9) Xanthan gum 0.1
(10) edetate trisodium 0.1
(11) Liquid paraffin 3.0
(12) Dimethylpolysiloxane 2.0
(13) Behenyl alcohol 0.5
(14) Isostearic acid 0.2
(15) Stearic acid 0.3
(16) Behenic acid 0.2
(17) Cetyl octanoate 5.0
(18) PEG-60 glyceryl isostearate 1.0
(19) PEG-5 glyceryl stearate 0.5
(20) Ascorbic acid glucoside 1.0
(21) Monoisostearic acid hydrogenated castor oil 2.0
(22) Perfume appropriate amount <Production method>
(11) to (22) were uniformly mixed and dissolved at 70 ° C. (oil phase). On the other hand, (1) to (10) were uniformly mixed and dissolved at 70 ° C. (aqueous phase). The mixture was emulsified with a homomixer while gradually adding the oil phase to the aqueous phase maintained at 70 ° C. When the emulsification was completed, the emulsion was rapidly cooled to 40 ° C. or lower to obtain a desired whitening skin care emulsion.
<Product properties>
About the obtained whitening skin care emulsion, when the same evaluation as in Examples 1 to 10 was performed, it was excellent in usability (usability evaluation, spreading on skin, stickiness, richness, freshness, and softening effect ◎), The stability was also good (stability evaluation: ◯).

  According to the present invention, as a thickener, in a composition having an organic solvent or oil as a dispersion medium and water as a dispersed phase, a water-soluble ethylenically unsaturated monomer is dissolved in the dispersed phase, and radical polymerization is performed in the dispersed phase. In order to impart a softening effect to the skin using the microgel obtained in this way, a composition with extremely excellent stability and usability can be obtained by blending hardened castor oil and an ester of higher fatty acid. Things are used as skin cosmetics.

  With regard to stability, it is possible to increase or decrease the viscosity due to separation such as oil floatation or gelation due to stability over time or centrifugation under low temperature 0 ° C storage, high temperature 50 ° C storage, and 5-45 ° C temperature cycle storage. It is not sticky and has excellent stability over time. In addition, as for usability, it is particularly non-sticky, lightly stretched, has both freshness and richness, and has excellent characteristics in terms of usability such as excellent softness to the skin.

The skin cosmetic of the present invention is also preferably used as an oil-in-water emulsified skin cosmetic such as an emulsion.

Claims (9)

(A) A composition comprising an organic solvent or oil as a dispersion medium and water as a dispersion phase, comprising a microgel obtained by dissolving a water-soluble ethylenically unsaturated monomer in the dispersion phase and radical polymerization in the dispersion phase. A thickener,
(B) A skin cosmetic comprising hydrogenated castor oil and an ester of a higher fatty acid. The skin cosmetic according to claim 1, wherein the water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1) and an ionic acrylamide derivative.
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.) The skin cosmetic according to claim 1 or 2, wherein the water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1) and an anionic acrylamide derivative represented by the general formula (2).
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (2)

(R ₄ and R ₅ each independently represent H or a methyl group, R ₆ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and X represents a metal ion or NH _3. ) The skin cosmetic according to claim 1 or 2, wherein the water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1) and a cationic acrylamide derivative represented by the general formula (3).
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (3)

(R ₇ is H or a methyl group, R ₈ is H or a linear or branched alkyl group having 1 to 6 carbon atoms, R ₉ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ₁₀ , R ₁₁ and R ₁₂ represent a methyl group or an ethyl group, and Y represents a metal ion.) The water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1), an anionic acrylamide derivative represented by the general formula (2), and a crosslinkable monomer represented by the general formula (4). The skin cosmetic according to claims 1 to 3.
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (2)

(R ₄ and R ₅ each independently represent H or a methyl group, R ₆ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and X represents a metal ion or NH _3. )

General formula (4)

The water-soluble ethylenically unsaturated monomer is a dialkylacrylamide represented by the general formula (1), a cationic acrylamide derivative represented by the general formula (3), and a crosslinkable monomer represented by the general formula (4). Item 1, 2, 4 skin cosmetics.
General formula (1)

(R ₁ represents H or a methyl group, and R ₂ and R ₃ each independently represents a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

General formula (3)

(R ₇ is H or a methyl group, R ₈ is H or a linear or branched alkyl group having 1 to 6 carbon atoms, R ₉ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ₁₀ , R ₁₁ and R ₁₂ represent a methyl group or an ethyl group, and Y represents a metal ion.)

General formula (4)

  7. The skin cosmetic according to claim 1, wherein the ester of (b) hydrogenated castor oil and a higher fatty acid is a monoester of hydrogenated castor oil and a higher fatty acid having 14 to 22 carbon atoms.   The blending amount of the thickener (a) is 0.01 to 2.5% by mass with respect to the total amount of the skin cosmetic, and the blending amount of the ester (b) is 0.00 with respect to the total amount of the skin cosmetic. The skin cosmetic according to claim 1, wherein the content is 01 to 5.0% by mass. The skin cosmetic according to claim 1, further comprising (c) an HLB 3-18 nonionic surfactant, wherein the skin cosmetic is an oil-in-water emulsion composition.