JP5073210B2 - Oil-in-water emulsion composition - Google Patents

Description

  The present invention relates to an oil-in-water emulsion composition useful for cosmetics and the like, a method for producing the same, and a cosmetic containing the same.

  The stratum corneum lipid is a substance that is found between the cells of the stratum corneum and forms a layered structure and contributes to the adhesion of the stratum corneum and the hydration of the stratum corneum. Ceramide, which occupies about 50%, is attracting attention as an active ingredient for skin with reduced moisture, such as rough skin, dry skin, and aging skin. However, natural ceramides and other ceramides have a very high melting point and high crystallinity, so they are stable in cosmetics and the like unless they are complex emulsion systems that use a large amount of oils and regular surfactants. Could not be blended.

  On the other hand, in recent years, higher safety is expected for cosmetics. From this viewpoint, it has been studied to produce an emulsified composition without using a commonly used low molecular surfactant. For example, PEMULEN TR-1 and TR-2 (Noveon), which are cross-linked acrylic acid / alkyl methacrylate copolymers, and ACULYN22 (Rohm & Haas) hydration gel known as a thickener, There is known a method of dispersing (Patent Documents 1 and 2, Non-Patent Document 1).

However, emulsified compositions obtained by emulsifying ceramides using only these cross-linked hydrophobically modified poly (meth) acrylates and thickeners have poor stability, and the appearance is transparent due to crystallization occurring over time. There was a need for improved usability.
JP 2000-264825 A JP-A-8-217624 FRAGRANCE JOURNAL, 1998-8, p.79

  An object of the present invention is to provide an oil-in-water emulsion composition that stably contains ceramides and has a high appearance transparency, a method for producing the same, and a cosmetic containing the same.

This invention contains the following (a) component and (b) component, and the viscosity in 25 degreeC exceeds 200 mPa * s, The manufacturing method and its oil-in-water emulsion composition are contained. To provide cosmetics.
(A) At least one selected from a structural unit represented by general formula (1) (hereinafter referred to as structural unit (1)) and a structural unit represented by general formula (2) (hereinafter referred to as structural unit (2)). Anionic amphiphilic composition comprising 50 to 90% by weight of all structural units and 10 to 50% by weight of the structural unit represented by the general formula (3) (hereinafter referred to as structural unit (3)). High molecular

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different and each represents a hydrogen atom or a methyl group, and R ⁷ is a linear or branched chain having 4 to 30 carbon atoms. An alkyl group or an alkenyl group, M ¹ , M ² and M ³ are the same or different and represent a hydrogen atom or a cationic group, and X ¹ represents an oxygen atom or NH.
(B) Ceramides The present invention also provides an oil-in-water emulsion composition further containing a thickener (component (c)), a method for producing the same, and a cosmetic containing the oil-in-water emulsion composition. .

  According to the present invention, it is possible to obtain an emulsified composition having a high appearance transparency in which ceramides are finely emulsified and crystallization is suppressed. The emulsified composition of the present invention can be suitably used as a cosmetic such as lotion, milky lotion or cream.

[(A) anionic amphiphilic polymer]
The anionic amphiphilic polymer as the component (a) of the present invention includes at least one structural unit (hereinafter referred to as an anionic structural unit) selected from the structural unit (1) and the structural unit (2) in the molecule. And a structural unit composed of the structural unit (3) (hereinafter referred to as a hydrophobic structural unit).

In the structural unit (1), R ¹ , R ² and R ³ represent a hydrogen atom or a methyl group, and those in which R ¹ and R ² are a hydrogen atom are preferred. In the structural units (1) and (2), M ¹ , M ^2, and M ³ represent a hydrogen atom or a cationic group, and examples of the cationic group include alkali metal ions such as Na and K, ammonium ions, and the like. Na and K are particularly preferable. Moreover, it is preferable that 5-100 mol% of a carboxyl group is a salt.

In the structural unit (3), R ⁴ , R ⁵ and R ^{6 each} represent a hydrogen atom or a methyl group, and those in which R ⁴ and R ⁵ are a hydrogen atom are preferred. R ⁷ represents a linear or branched alkyl group or alkenyl group having 4 to 30 carbon atoms. From the viewpoint of emulsion stability, R ⁷ is preferably one having 8 to 30 carbon atoms, particularly 12 to 22 carbon atoms. Specific examples include an octyl group, 2-ethylhexyl group, decyl group, lauryl group, myristyl group, cetyl group, stearyl group, oleyl group, and behenyl group. X ¹ represents an oxygen atom or NH, preferably an oxygen atom.

  The proportion of the anionic structural unit in all the structural units of the anionic amphiphilic polymer is 50 to 90% by weight, preferably 50 to 85% by weight, from the viewpoint of obtaining high emulsion stability of ceramides. 50 to 80% by weight is particularly preferred. Moreover, the ratio of the hydrophobic structural unit in all the structural units of the anionic amphiphilic polymer is 10 to 50% by weight from the viewpoint of obtaining high emulsification stability of ceramides, and 20 to 50% by weight. Preferably, 30 to 50% by weight is particularly preferable. The content of each structural unit in the anionic amphiphilic polymer can be measured by dissolving the polymer in deuterium-substituted dimethyl sulfoxide and using a proton nuclear magnetic resonance spectrum.

  The anionic amphiphilic polymer has both the anionic structural unit and the hydrophobic structural unit, but the arrangement of each structural unit may be random or block. Moreover, although it may contain 1 or more types of structural units other than the above, the bifunctional monomer component which gives the crosslinked anionic amphiphilic polymer from a viewpoint of obtaining an emulsion composition with high appearance transparency It is preferable not to use.

  The weight average molecular weight of the anionic amphiphilic polymer is preferably 200,000 or less, more preferably 1,000 to 200,000, and still more preferably 10,000 to 100,000. In addition, a weight average molecular weight is the value measured by GPC (gel permeation chromatography), and the detail of measurement conditions is as showing in an Example.

  The anionic amphiphilic polymer is preferably one that forms micelles in water. The formation of micelles in water means that the hydrophobic structural unit of the amphiphilic polymer undergoes self-organization by hydrophobic interaction between molecules or within the molecule.

  The formation of micelles can be confirmed by static light scattering, fluorescent probe, NMR, ESR using spin probe, small angle neutron scattering method, etc. (Yotaro Morishima, Surface, Vol.34, No.11, 1996, p672; Yotaro Morishima , Polymer, 46, March, 1997, p128; Yotaro Morishima, Journal of Japan Oil Chemists' Society, Vol. 45, 10, 1996, p951; Kazunari Akiyoshi, Surface, Vol.37, No.1, 1999 , p29).

  The anionic amphiphilic polymer can be obtained by a known synthesis method. For example, a monomer constituting at least one anionic constituent unit selected from the constituent unit (1) and the constituent unit (2) and a monomer constituting the hydrophobic constituent unit of the constituent unit (3) are polymerized by a solution polymerization method. It is obtained by doing. Here, each monomer is represented by general formula (4), (5), (6), respectively.

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , M ¹ , M ² , M ³ and X ¹ have the same meaning as described above.)
Examples of the monomer represented by the general formula (4) include acrylic acid, methacrylic acid, and salts thereof. Examples of the monomer represented by the general formula (5) include maleic acid or a salt thereof. Examples of the salt include alkali metal salts such as Na salt and K salt, ammonium salt, and amine salt, and Na salt and K salt are particularly preferable.

  As a monomer represented by the general formula (6), butyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, butyl (meth) acrylamide, octyl Examples include (meth) acrylamide, lauryl (meth) acrylamide, stearyl (meth) acrylamide, and behenyl (meth) acrylamide. Of these, lauryl (meth) acrylate and stearyl (meth) acrylate are preferred.

  Examples of the solvent used for the solution polymerization of the above monomers include organic compounds such as aromatic compounds (toluene, xylene, etc.), lower alcohols (ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone), tetrahydrofuran, diethylene glycol dimethyl ether, etc. can do. The amount of solvent (by weight) is preferably equivalent to 20 times, particularly preferably 10 to 10 times the total amount of monomers.

  As the polymerization initiator, known radical initiators can be used, and examples thereof include azo polymerization initiators, hydroperoxides, dialkyl peroxides, diacyl peroxides, and ketone peroxides. If necessary, basic catalysts (metals such as lithium, sodium, potassium, cesium, alkoxides, hydroxides, etc.) or acidic catalysts (sulfuric acid, hydrochloric acid, etc.) may be used. The amount of the polymerization initiator is preferably in the range of 0.01 to 5 mol%, particularly 0.01 to 3 mol%, more preferably 0.01 to 1 mol%, based on the total monomers.

  The polymerization reaction is preferably performed in a temperature range of 60 to 180 ° C. under a nitrogen stream, and the reaction time is preferably 0.5 to 20 hours.

  In the emulsion composition of the present invention, one or more anionic amphiphilic polymers as the component (a) can be used, and the content of the component (a) in the emulsion composition is 0.01 to 10 weight%, especially 0.1-10 weight% is preferable from a viewpoint of obtaining a favorable usability.

[(B) Ceramides]
The ceramides as the component (b) of the present invention are generic names of natural ceramides and structurally similar substances, and include those represented by the general formula (7) or (8).

(In the formula, R ¹¹ represents a hydrocarbon group having 4 to 30 carbon atoms which may be substituted by a hydroxyl group, a carbonyl group or an amino group. Z represents a methylene group, a methine group or an oxygen atom; X ¹¹ , X ¹² and X ¹³ each independently represent a hydrogen atom, a hydroxyl group or an acetoxy group, and when Z is a methine group, X ¹¹ and X ¹² Either one is a hydrogen atom and the other does not exist, X ¹⁴ represents a hydrogen atom, an acetyl group or a glyceryl group, or X ¹³ —C—O—X ¹⁴ represents C═O, in which case X ¹³ and X ¹⁴ does not exist, R ¹² and R ¹³ each independently represent a hydrogen atom, a hydroxyl group, a hydroxymethyl group or an acetoxymethyl group, and R ¹⁴ may be substituted with a hydroxyl group, a carbonyl group or an amino group. , Ether bond to the main chain Or .R ¹⁵ showing the hydrocarbon group of the ester or amide bond carbon atoms 5 to 60 which may have a represents a hydrogen atom, a hydroxyl group, hydroxyalkoxy group, substituent selected from alkoxy and acetoxy groups And represents a hydrocarbon group having 1 to 8 carbon atoms in total, and R ¹⁶ represents a hydrocarbon group having 10 to 30 carbon atoms.)

In the general formulas (7) and (8), R ¹¹ is preferably a hydrocarbon group having 7 to 22 carbon atoms which may be substituted with a hydroxyl group. Z, X ¹¹ , X ¹² and X ¹³ have the above meanings, and it is particularly preferable that 0 to 1 of X ¹¹ , X ¹² and X ¹³ are hydroxyl groups and the remainder is a hydrogen atom. When Z is a methine group, only one of X ¹¹ and X ¹² is a hydrogen atom, and the other does not exist. X ¹⁴ is preferably a hydrogen atom or a glyceryl group.

R ¹² and R ¹³ have the above-mentioned meanings. Preferred R ¹² is a hydrogen atom or a hydroxymethyl group, and preferred R ¹³ is a hydrogen atom.

R ¹⁴ is preferably a hydrocarbon group having 5 to 35 carbon atoms which may be substituted with a hydroxyl group or an amino group, or 8 carbon atoms which a hydroxyl group may be substituted at the ω-position of the hydrocarbon group. ˜22 fatty acids are ester-bonded or amide-bonded. As the fatty acid to be bonded, isostearic acid, 12-hydroxystearic acid or linoleic acid is preferable.

R ¹⁵ is preferably a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms in which 1 to 3 groups selected from a hydroxyl group, a hydroxyalkoxy group and an alkoxy group may be substituted. Here, as a hydroxy alkoxy group and an alkoxy group, a C1-C7 thing is preferable.

  The ceramides represented by the general formula (7) are particularly represented by natural or natural ceramides represented by the following general formula (9) and derivatives thereof (hereinafter referred to as natural ceramide) or the general formula (10). Ceramides (hereinafter referred to as pseudo-ceramide) are preferred.

(In the formula, R ²¹ represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 7 to 19 carbon atoms which may be substituted by a hydroxyl group. Z ¹ represents a methylene group or a methine group. The broken line portion indicates that it may be an unsaturated bond, X ¹⁵ , X ¹⁶ and X ¹⁷ each independently represent a hydrogen atom, a hydroxyl group or an acetoxy group, and when Z ¹ is a methine group, ^{One of 15} and X ¹⁶ is a hydrogen atom and the other does not exist, X ¹⁸ represents a hydrogen atom, or X ¹⁷ —C—O—X ¹⁸ represents C═O, in which case X ¹⁷ and X ¹⁸ does not exist, R ²² represents a hydroxymethyl group or an acetoxymethyl group, R ²³ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ²⁴ may be substituted with a hydroxyl group. C5-C30 straight chain, branched chain or cyclic saturated or unsaturated hydrocarbon Or it is, or the ω-terminal of the hydrocarbon group, those hydroxyl groups are saturated or unsaturated fatty acid, linear or branched chain having 8 to 22 carbon atoms which may be substituted with an ester bond.)

(In the formula, R ²⁵ represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 10 to 22 carbon atoms which may be substituted with a hydroxyl group; X ¹⁹ represents a hydrogen atom or an acetyl group; Or a glyceryl group; R ²⁶ is a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 5 to 22 carbon atoms which may be substituted by a hydroxyl group or an amino group; Indicate an ester bond of a linear or branched saturated or unsaturated fatty acid having 8 to 22 carbon atoms which may be substituted with a hydroxyl group at the ω-terminal of the hydrogen group; does R ²⁷ represent a hydrogen atom? , A hydroxyalkoxy group, an alkoxy group, or an acetoxy group represents an alkyl group having 1 to 8 carbon atoms that may be substituted.)

In natural ceramide represented by the general formula (9), preferably, R ²¹ is 7 to 19 carbon atoms, more preferably a linear alkyl group having 13 to 15 carbon atoms; even be substituted with R ²⁴ is a hydroxyl group Examples thereof include a compound having a good linear alkyl group having 9 to 27 carbon atoms or a linear alkyl group having 9 to 27 carbon atoms in which linoleic acid is ester-bonded. X ¹⁸ preferably represents a hydrogen atom or forms an oxo group together with an oxygen atom. In particular, R ²⁴ is preferably tricosyl, 1-hydroxypentadecyl, 1-hydroxytricosyl, heptadecyl, 1-hydroxyundecyl, or a nonacosyl group in which linoleic acid is ester-bonded to the ω position.

  Specific examples of natural ceramides include ceramide types 1 to 7 in which sphingosine, dihydrosphingosine, phytosphingosine or sphingadienin is amidated (for example, J. Lipid Res., 24: 759 (1983), FIG. And porcine and human ceramides described in FIG. 4 of J. Lipid. Res., 35: 2069 (1994)).

  Specific examples include those represented by the following formula.

  Furthermore, these N-alkyl bodies (for example, N-methyl body) are also included. These may be any of natural extracts and synthetic products, and commercially available products can be used.

  These ceramides may be either natural (D (−)) optically active or non-natural (L (+)) optically active, or a mixture of natural and nonnatural. May be used. The relative configuration of the above compound may be a natural configuration, a non-natural configuration other than that, or a mixture thereof. In particular, compounds of CERAMIDE1, CERAMIDE2, CERAMIDE3, CERAMIDE5, CERAMIDE6II (above, INCI, 8th Edition) and those represented by the following formula are preferable.

  In addition, commercially available natural ceramides include Ceramide I, Ceramide III, Ceramide IIIA, Ceramide IIIB, Ceramide IIIC, Ceramide VI (above, manufactured by Cosmo Farm), Ceramide TIC-001 (manufactured by Takasago Inc.), CERAMIDE II (made by Quest International), DS-Ceramide VI, DS-CLA-Phytoceramide, C6-Phytoceramide, DS-ceramide Y3S (made by DOOSAN), CERAMIDE2 (made by Sederma).

In the pseudoceramide represented by the general formula (10), as R ²⁶ , nonyl, tridecyl, pentadecyl, an undecyl group in which linoleic acid is ester-bonded to the ω position, a pentadecyl group in which linoleic acid is ester-bonded to the ω position, ω A pentadecyl group in which 12-hydroxystearic acid is ester-bonded at the position and an undecyl group in which methyl-branched isostearic acid is amide-bonded at the ω position are preferable. The hydroxyalkoxy or alkoxy group R ²⁷ preferably has 1 to 8 carbon atoms.

As the pseudo-ceramide represented by the general formula (10), R ²⁵ is a hexadecyl group, X ¹⁹ is a hydrogen atom, R ²⁶ is a pentadecyl group, and R ²⁷ is a hydroxyethyl group (N- (3-hexadecyloxy- 2-hydroxypropyl) -N-2-hydroxyethyl-hexadecanol cyanamide: see JP-A-62-228048); R ²⁵ is hexadecyl, X ¹⁹ is a hydrogen atom, R ²⁶ is a nonyl group, R ²⁷ is hydroxy Pseudo-ceramides having an ethyl group; or R ²⁵ is a hexadecyl group, X ¹⁹ is a glyceryl group, R ²⁶ is a tridecyl group, and R ²⁷ is a 3-methoxypropyl group, and R ^{25 in the} general formula (10) is hexadecyl. Particularly preferred are those wherein X ¹⁹ is a hydrogen atom, R ²⁶ is a pentadecyl group and R ²⁷ is a hydroxyethyl group.

  In the emulsified composition of the present invention, one or more ceramides as the component (b) can be used, and the content of the component (b) in the emulsified composition is 0.01 to 15% by weight, particularly 0. 0.1 to 5% by weight is preferable from the viewpoint of obtaining a good feeling of use and a high moisturizing effect.

[(C) Thickener]
The thickener which is the component (c) of the present invention can be dissolved in an aqueous component to impart viscosity, and any may be used as long as it can be used in cosmetics. For example, poly (meth) acrylic acid, methacrylic acid / acrylic acid copolymer, (meth) acrylic acid / (meth) alkyl acrylate copolymer (content of alkyl (meth) acrylate is 10% by weight in all structural units) (Meth) acrylic acid polymers such as guar gum, hydroxypropyl guar gum, xanthan gum, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxyethyl (hydroxypropyl polyethylene glycol dodecyl ether) cellulose), pullulan, dextran, carrageenan , Polysaccharides such as pectin and starch or derivatives thereof; other water-soluble polymers such as polyvinyl alcohol. As the (meth) acrylic acid polymer, those having a weight average molecular weight of 300,000 or more and cross-linked are preferable. These thickeners may be used alone or in combination of two or more.

  The blending amount of the thickener in the emulsified composition of the present invention is preferably 0.01 to 10% by weight, particularly 0.01 to 3% by weight from the viewpoint of obtaining a good feeling of use.

[Other ingredients]
The emulsion composition of the present invention can further contain an oily component. Such an oil component may be volatile or non-volatile, and may be solid, pasty, or liquid as a form at normal temperature. For example, hydrocarbons such as solid or liquid paraffin, petrolatum, ceresin, ozokerite, montan wax, squalane, squalene; eucalyptus oil, mint oil, camellia oil, macadamia nut oil, avocado oil, beef fat, pork fat, horse oil, egg yolk oil Oils such as olive oil, carnauba wax, lanolin, jojoba oil; glycerol monostearate, glycerol distearate, glycerol monooleate, isopropyl palmitate, isopropyl stearate, butyl stearate, isopropyl myristate, neocapric acid neo Pentyl glycol, diethyl phthalate, myristyl lactate, diisopropyl adipate, cetyl myristate, cetyl lactate, 1-isostearoyl-3-myristoyl glycerol, 2-ethylhexa Cetyl acid, 2-ethylhexyl palmitate, 2-octyldodecyl myristate, neopentyl glycol di-2-ethylhexanoate, 2-octyldecyl oleate, glycerol triisostearate, diparamethoxycinnamate mono-2-ethylhexanoate glyceryl, etc. Ester oil; higher fatty acids such as stearic acid, palmitic acid and oleic acid; higher alcohols such as stearyl alcohol and cetyl alcohol; natural essential oils such as rosemary, rooibos, royal jelly, and hamelis; lignan, vitamin E, oil-soluble vitamin C, vitamin In addition to functional oily substances such as A derivatives, oil-soluble ultraviolet absorbers, and fragrances, silicones, fluorine-based oils and the like can be mentioned.

  Examples of silicones are those usually used in toiletry products. For example, octamethylpolysiloxane, tetradecamethylpolysiloxane, methylpolysiloxane, highly polymerized methylpolysiloxane, methylphenylpolysiloxane; octamethylcyclotetrasiloxane, decamethylcyclo Methylcyclopolysiloxane such as pentasiloxane; trimethylsiloxysilicic acid; alkyl-modified silicone, polyether-modified silicone, amino acid-modified silicone, amino-modified silicone, fluorine-modified silicone, alkylglyceryl ether-modified silicone, alkyl, alkenyl or fluoroalkyl-modified silicone, etc. Of the modified silicone.

  As the fluorinated oil agent, perfluoropolyether which is a perfluoro organic compound which is liquid at normal temperature is preferable. For example, perfluorodecalin, perfluoroadamantane, perfluorobutyltetrahydrofuran, perfluorooctane, perfluorononane, perfluoropentane. Perfluorodecane, perfluorododecane, perfluoropolyether and the like.

  In the emulsion composition of the present invention, one or more of these oily components can be used, and the content of these oily components in the emulsion composition is 0.01 to 30% by weight, particularly 0.1 to 10% by weight. % Is preferable from the viewpoint of obtaining a good feeling of use.

  In the emulsified composition of the present invention, water can be optionally blended, but the water content in the emulsified composition is preferably 50 to 95% by weight, particularly 60 to 95% by weight from the viewpoint of obtaining a good feeling of use. .

  The emulsion composition of the present invention can further contain a water-soluble organic solvent. Examples of the water-soluble organic solvent include lower alcohols such as ethanol and isopropanol; glycols such as ethylene glycol, propylene glycol, dipropylene glycol, isoprene glycol, 1,3-butylene glycol, and polyethylene glycol (average molecular weight 200 to 1540); Examples thereof include polyhydric alcohols such as polyoxyethylene methyl glucoside, glycerin, and diglycerin; tris (2- (2-ethoxyethoxy) ethyl) phosphate, and the like, and one or more can be used.

  The content of the water-soluble organic solvent in the emulsified composition of the present invention is preferably 0.1 to 30% by weight, particularly 0.1 to 20% by weight from the viewpoint of obtaining a good feeling of use.

[Method for producing emulsified composition]
The emulsified composition of the present invention is prepared by, for example, mixing the component (a) and the component (b) (other oily components if necessary) in a water-soluble organic solvent, and adding water to the resulting solution or dispersion. Further, if necessary, it can be produced by adding the component (c). The emulsification operation is desirably performed under heating (for example, about 40 to 80 ° C.).

  Specifically, first, the component (a) and the component (b) (other oily components if necessary) are dissolved or dispersed in a water-soluble organic solvent. Further, a mixed solvent of a water-soluble organic solvent and water can be used as long as the solubility of the component (a) is not hindered (for example, 86% glycerin aqueous solution). After adding and mixing the component (a) and the component (b), it is preferable to hold for 10 minutes or more, particularly 15 to 60 minutes, because an emulsion composition with more stability can be obtained.

  The composition after adding and mixing the component (a) and the component (b) is in a blue transparent to white gel state. In this state, it is generally considered that the continuous phase is a water-soluble organic solvent because of electrical conductivity, and the component (b) is held in the hydrophobic part of the component (a) dissolved or dispersed in the water-soluble organic solvent. It is done. Next, after adding water or an aqueous solution containing a desired water-soluble component in an arbitrary ratio to the obtained oil-based mixture, the component (c) is further mixed as necessary to obtain an oil-in-water emulsion composition. Obtainable.

  In addition, when the carboxy group of component (a) forms a salt, after synthesizing an anionic amphiphilic polymer having a free carboxyl group, a base is mixed with the anionic amphiphilic polymer. Then, a salt may be formed. The base may be mixed with a water-soluble organic solvent together with the anionic amphiphilic polymer, or may be mixed by dissolving in water. In the composition, the carboxyl group of the anionic amphiphilic polymer is salted. It only has to be formed. Examples of the base include potassium hydroxide and sodium hydroxide. The pH of the emulsified composition is preferably pH 3.0 to 6.8, particularly preferably pH 4.0 to 6.5.

  In the present invention, in order to add and mix each component, stirring and mixing may be performed by an ordinary method. For example, a homogenizer, an ultrasonic emulsifier, a high-pressure emulsifier, or the like can be used.

[Oil-in-water emulsion composition]
The oil-in-water emulsion composition of the present invention contains the components (a) and (b) as essential components, and the absence of a surfactant other than the component (b) reduces the irritation to the skin. To preferred.

  In the present invention, the transparency of the appearance of the emulsion can be controlled by using the component (a). In particular, in the present invention, since a substantially non-crosslinked anionic amphiphilic polymer is used as the component (a), the visible light transmittance is preferably 20 to 100%, more preferably 30 to 100%. Emulsion can be obtained, and an emulsion composition having high transparency in appearance can be obtained.

  In the present invention, the visible light transmittance is measured using a spectrophotometer UV-2550 (manufactured by Shimadzu Corporation). These visible light transmittance measurements are performed at 25 ° C.

  Further, the viscosity of the emulsion composition obtained in the present invention can be arbitrarily adjusted and can be appropriately adjusted depending on the purpose of use, but the viscosity at 25 ° C. needs to exceed 200 mPa · s and is used as a gel. In this case, 300 mPa · s or more is preferably used. There is no particular upper limit, but 100,000 mPa · s or less is preferable in terms of touch. In the present invention, the viscosity is measured with a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., B8L type) at 25 ° C.

[Cosmetics]
The emulsified composition of the present invention can be suitably used as a cosmetic. Examples of cosmetics include foundations, lotions, creams, emulsions, lotions, gels, skin softening cosmetics, nutritional cosmetics, astringent cosmetics, whitening cosmetics, wrinkle improving cosmetics, anti-aging cosmetics, and antiperspirants. Skin cosmetics such as deodorants; hair cosmetics such as hair styling agents and hair nourishing agents.

  Cosmetics contain preservatives, antioxidants, fragrances, UV absorbers, moisturizers, blood circulation promoters, cooling agents, antiperspirants, fungicides, skin protectants, water-soluble polymers, plant extracts, etc. can do. Viscosity and pH preferable as a cosmetic are the same as those of the above-mentioned emulsion composition.

  In the following synthesis examples, the weight average molecular weight of the anionic amphiphilic polymer is a polystyrene-reduced weight average molecular weight obtained by measuring a 0.5 wt% solution of the polymer in chloroform under the following conditions by GPC.

<GPC measurement conditions>
Column: 2 α-Ms manufactured by Tosoh Corporation, eluent: 60 mmol / L H ₃ PO ₄ 50 mmol / L LiBr / N, N-dimethylformamide solution, flow rate: 1.0 mL / min, column temperature: 40 ° C., detector : Differential refractometer.

  In the following synthesis examples, the average weight percentage of each structural unit in the anionic amphiphilic polymer was determined by measuring a 1 wt% solution of the polymer in deuterium-substituted dimethyl sulfoxide by proton nuclear magnetic resonance spectrum. .

Synthesis Example 1 (Synthesis of anionic amphiphilic polymer A)
A reactor equipped with a dropping funnel, a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 1/10 amount of a mixed solution consisting of 67 g of acrylic acid, 33 g of stearyl acrylate, and 67 g of a polymerization solvent isopropyl alcohol, and mixed. The rest of the liquid and 0.5 g of initiator V-65 (manufactured by Wako Pure Chemical Industries, Ltd.) were added dropwise at 75 ° C. for 2.5 hours using a dropping funnel. After aging for 1 hour after the completion of dropping, 0.2 g of initiator V-65 was added three times every 30 minutes. Thereafter, the reaction temperature was raised to 80 ° C., and after 1 hour, the reaction was terminated. Using a ceramic membrane purifier made of alumina having a pore diameter of 500 mm, unreacted monomers and initiator residues were removed from the reaction product and dried to obtain an anionic amphiphilic polymer A. The obtained anionic amphiphilic polymer A had a weight average molecular weight of 35,000. The content of the acrylic acid structural unit in the obtained anionic amphiphilic polymer A was 67% by weight, and the content of the stearyl acrylate structural unit was 33% by weight.

Example 1
Under stirring at 80 ° C., the anionic amphiphilic polymer A and ceramide (Sofcare Ceramide SL-E, manufactured by Kao Corporation) were dissolved in a water-soluble organic solvent (tris (2- (2-ethoxyethoxy) ethyl) phosphate). ), An aqueous solution in which potassium hydroxide and methylparaben (methyl paraoxybenzoate) are dissolved in purified water is added with stirring. After cooling to 20 ° C., the purified water is cross-linked with purified water. An aqueous solution in which poly (meth) acrylate (Carbopol 980, manufactured by Noveon) was dissolved was added to prepare an emulsion composition.

Examples 2-3
In the same manner as in Example 1, except that hydroxyethyl (hydroxypropyl polyethylene glycol dodecyl ether) cellulose (Sofcare HE-2120DA, Kao) was used instead of the crosslinked poly (meth) acrylate (Carbopol 980, manufactured by Noveon). Co., Ltd.) and xanthan gum (Echo Gum T, manufactured by Dainippon Pharmaceutical Co., Ltd.) were used to prepare an emulsion composition.

Comparative Example 1
Under stirring at 80 ° C., a crosslinked poly (meth) acrylate (Carbopol 980, manufactured by Noveon) and ceramide (Sofcare Ceramide SL-E, manufactured by Kao Corporation) were dissolved in a water-soluble organic solvent (Tris (2- After being dissolved in (2-ethoxyethoxy) ethyl) phosphate), an aqueous solution in which potassium hydroxide and methylparaben (methyl paraoxybenzoate) were dissolved in purified water was added with stirring to prepare an emulsion composition. Crystal precipitation was observed in the obtained emulsified composition.

Comparative Example 2
Similar to Comparative Example 1, except that a crosslinked acrylic acid / alkyl methacrylate copolymer (PEMULEN TR-1, Noveon) was used instead of the crosslinked poly (meth) acrylate (Carbopol 980, manufactured by Noveon). An emulsion composition was prepared using Crystal precipitation was observed in the obtained emulsified composition.

  About the above emulsified composition, the compounding quantity of each component, the transmittance | permeability of visible light in the obtained emulsified composition, and the viscosity in 25 degreeC are shown collectively in Table 1. Moreover, the presence or absence of crystal precipitation was evaluated by polarizing microscope observation. The results are also shown in Table 1. All the emulsified compositions were confirmed to be oil-in-water by electric conductivity.

In the emulsified composition shown in the examples, crystallization was suppressed and the appearance was highly transparent. Moreover, when the emulsified composition obtained in the examples was used on the skin as a cosmetic, it had a good feeling of use that was easy to adjust and moist.

Claims (8)

An oil-in-water emulsion composition containing the following component (a) and component (b) and having a viscosity at 25 ° C. exceeding 200 mPa · s.
(A) 50-80 wt% of at least one structural unit selected from the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2), ) Anionic amphiphilic polymer containing 20-50% by weight of all structural units

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different and each represents a hydrogen atom or a methyl group, and R ⁷ is a straight or branched chain having 12 to 22 carbon atoms. An alkyl group or an alkenyl group, M ¹ , M ² and M ³ are the same or different and represent a hydrogen atom or a cationic group, and X ¹ represents an oxygen atom or NH.
(B) one or more selected from natural ceramides represented by general formula (9) and pseudo-ceramides represented by general formula (10)

(In the formula, R ²¹ represents a linear saturated or unsaturated hydrocarbon group having 7 to 19 carbon atoms which may be substituted by a hydroxyl group. Z ¹ represents a methylene group or a methine group, X ¹⁵ , X ¹⁶ and X ¹⁷ each independently represent a hydrogen atom or a hydroxyl group, and when Z ¹ is a methine group, either X ¹⁵ or X ¹⁶ One is a hydrogen atom and the other does not exist, X ¹⁸ represents a hydrogen atom, R ²² represents a hydroxymethyl group, R ²³ represents a hydrogen atom, R ²⁴ represents the number of carbon atoms that the hydroxyl group may substitute. A straight-chain, branched-chain, or cyclic saturated or unsaturated hydrocarbon group having 5 to 30 carbon atoms, or a straight chain having 8 to 22 carbon atoms that may be substituted with a hydroxyl group at the ω-terminal of the hydrocarbon group. (A chain or branched chain saturated or unsaturated fatty acid with an ester bond.)

(In the formula, R ²⁵ represents a linear saturated or unsaturated hydrocarbon group having 10 to 22 carbon atoms which may be substituted with a hydroxyl group; X ¹⁹ represents a hydrogen atom or a glyceryl group; R ²⁶ Is a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 5 to 22 carbon atoms which may be substituted by a hydroxyl group or an amino group, or a hydroxyl group at the ω-terminal of the hydrocarbon group A linear or branched saturated or unsaturated fatty acid having 8 to 22 carbon atoms which may be substituted with an ester; R ²⁷ represents a hydroxyethyl group or a 3-methoxypropyl group.   The oil-in-water emulsion composition according to claim 1, wherein the anionic amphiphilic polymer (a) has a weight average molecular weight of 200,000 or less.   The oil-in-water emulsion composition according to claim 1 or 2, which does not contain a surfactant.   Furthermore, the oil-in-water emulsion composition in any one of Claims 1-3 containing a thickener ((c) component).   Furthermore, the oil-in-water type emulsion composition in any one of Claims 1-4 containing a water-soluble organic solvent.   Dependent on claim 4 obtained by mixing component (a) and component (b) in a water-soluble organic solvent, adding water to the resulting solution or dispersion, and then adding component (c). The oil-in-water emulsion composition according to claim 5.   The oil-in-water according to claim 6, wherein the component (a) and the component (b) are mixed in a water-soluble organic solvent, and water is added to the obtained solution or dispersion, and then the component (c) is further added. A method for producing a mold emulsion composition.   Cosmetics containing the oil-in-water emulsion composition in any one of Claims 1-6.