JP7705109B2 - Skin preparations - Google Patents

Description

The present invention relates to an external skin preparation containing microcapsules encapsulating an ultraviolet absorbent, which has excellent storage stability. More specifically, the present invention relates to an external skin preparation that is formulated in combination with (A) microcapsules encapsulating an ultraviolet absorbent, with a wall material being a copolymer of a silylated peptide and a silane compound or a copolymer of a silylated amino acid and a silane compound, and (B) a specific aqueous thickener, thereby suppressing viscosity changes over time during storage and suppressing aggregation and precipitation of the microcapsules.

Organopolysiloxanes are used in a wide range of fields due to their excellent properties, such as thermal and mechanical stability, light resistance, and bioinertness. In the field of microcapsules such as microcapsules and nanocapsules, microcapsules are manufactured using organopolysiloxanes or similar compounds as wall materials, and the present inventors have also developed microcapsules containing an ultraviolet absorber and using a copolymer of a silylated peptide and a silane compound as wall material, as an excellent ultraviolet protection agent (Patent Document 1).

Furthermore, we have developed UV absorber-encapsulated microcapsules that use a copolymer of a silylated amino acid and a silane compound as the wall material, and that have little leakage of the encapsulated material, are almost odorless due to the wall material, have a wide pH range, and are highly stable when incorporated into cosmetics without associating with coexisting substances, and can fully exert the activity of the encapsulated material.We have also developed cosmetics that incorporate these microcapsules (Patent Document 2).

However, when these microcapsules containing an ultraviolet absorber are included in topical skin preparations, depending on the formulation, it may be difficult to maintain the dispersibility of the microcapsules, as the microcapsules may aggregate over time during storage and the aggregates may settle. Even when a thickener is included to maintain dispersibility, the viscosity may increase or decrease over time, which may impair storage stability, and depending on the type of thickener, the feel of use, such as non-stickiness and good skin compatibility, may be reduced when applied to the skin.

Japanese Patent Application Publication No. 11-221459 JP 2017-218392 A

The present invention aims to provide an external skin preparation for UV protection in which microcapsules containing an ultraviolet absorbing agent are uniformly dispersed, the microcapsules are not likely to aggregate or the aggregates are likely to precipitate during storage, and the viscosity of the external skin preparation is not likely to change over time.

As a result of intensive research in light of the above-mentioned circumstances, the present inventors have found that by combining and formulating ultraviolet absorber-containing microcapsules having a wall membrane made of a silylated peptide/silane compound copolymer or a silylated amino acid/silane compound copolymer obtained by condensation polymerization in an aqueous solution of one or more silylated peptides or silylated amino acids having two or more hydroxyl groups directly bonded to silicon atoms, or one or more silane compounds which upon hydrolysis generate two or more hydroxyl groups directly bonded to silicon atoms, and a specific aqueous thickener, the aggregation and precipitation of the microcapsules during storage can be suppressed, and an excellent topical skin preparation with little change in viscosity over time can be obtained, thereby completing the present invention.
That is, the above-mentioned problems are solved by an external skin preparation having the following configuration.

In a first aspect, the present invention provides a polymerizable composition comprising: (A) a structural unit U represented by the following general formula (Ia), (Ib) or (Ic):
[In the formula, R ² represents an alkyl group having 1 to 20 carbon atoms, and each R ² may be the same or different.]
and a structural unit W represented by the following general formula (Id) or (Ie):
[In the formula, R ¹ represents an alkyl group having 1 to 3 carbon atoms, each R ¹ may be the same or different, A represents a divalent group bonding Si and N, and is one selected from the group consisting of -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, *-(CH ₂ ) ₃ OCH ₂ CH(OH)CH ₂ - and *-(CH ₂ ) ₃ OCOCH ₂ CH ₂ -(wherein * represents the side bonding to Si), and E represents a residue obtained by removing one primary amino group from a polypeptide or an α-amino acid having a number average molecular weight of 100 to 50,000), or an encapsulated microcapsule having a wall membrane made of the silylated amino acid/silane compound copolymer and encapsulating an ultraviolet absorber therein; and (B) an external preparation for the skin characterized by containing an aqueous thickener selected from a composition containing an acrylamide compound, a nonionic surfactant, and a hydrocarbon oil, a bisstearyl PEG/PPG-8/6 (SMDI/PEG-400) copolymer, and xanthan gum.

The second aspect of the present invention is a skin topical preparation according to the first aspect of the present invention, characterized in that the acrylamide-based compound is selected from polyacrylamide, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymer, (sodium acrylate/sodium acryloyldimethyltaurate) copolymer, (acrylamide/ammonium acrylate) copolymer, (acrylamide/sodium acryloyldimethyltaurate) copolymer, and polyacrylate-13. When the acrylamide-based compound in the composition containing an acrylamide-based compound, a nonionic surfactant, and a hydrocarbon oil is one of these specific acrylamide-based compounds, the skin topical preparation according to the present invention is excellent in terms of the effect of maintaining the dispersibility of the microcapsules containing an ultraviolet absorber therein and the effect of suppressing viscosity changes during storage, and therefore the second aspect of the present invention corresponds to this preferred embodiment.

The present invention is a topical skin preparation for UV protection that contains microcapsules encapsulating an ultraviolet absorbing agent, and the capsules are uniformly dispersed in the preparation, and are unlikely to aggregate or precipitate even during storage. In addition, the present invention is excellent in that the viscosity change over time is suppressed, and the stability of the formulation of the topical skin preparation is maintained. When applied to the skin, the preparation exhibits excellent UV protection effects while also exhibiting a favorable feel in use, such as low stickiness and good skin compatibility.

The components constituting the topical skin preparation of the present invention, (A) microcapsules containing an ultraviolet absorbing agent and (B) aqueous thickener, as well as the form of the topical skin preparation of the present invention, are described in detail below.

[Microcapsules containing UV absorbent]
The microcapsules containing an ultraviolet absorber, which are component (A) incorporated in the topical skin preparation of the present invention, are microcapsules having an ultraviolet protection effect, in which an ultraviolet absorber is encapsulated in a capsule whose wall material is a copolymer of a silylated peptide and a silane compound, or in which a capsule whose wall material is a copolymer of a silylated amino acid and a silane compound, and these microcapsules can be produced by the method described in Patent Document 1 or Patent Document 2, and the specific method is as follows.

The microcapsules containing an ultraviolet absorber and having a wall made of a copolymer of a silylated peptide and a silane compound are represented by the following general formula (III):
[wherein R ¹¹ represents a hydroxyl group or an alkyl group having 1 to 3 carbon atoms, and A1 represents a bond and at least one group selected from the group consisting of -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, *-(CH ₂ ) ₃ OCH ₂ CH(OH)CH ₂ -, and *-(CH ₂ ) ₃ OCOCH ₂ CH ₂ - (* represents the side bonded to Si)], and a silylated peptide having a silyl group represented by the following general formula (IV):
R ²¹ mSi(OH)nY(4-nm) (IV)
[wherein R ²¹ represents an alkyl group or a phenyl group having 1 to 20 carbon atoms, m represents an integer from 0 to 3, and m R ^21s may be the same or different, n represents an integer from 0 to 4, m+n≦4, and (4−n−m) Ys represent an alkoxy group having 1 to 6 carbon atoms, a halogen group, or a hydrogen atom.] in a dispersion in which the ultraviolet absorber to be included is dispersed in a continuous phase made of an aqueous substance.

The silylated peptide can be produced, for example, by the production method described in JP-A-8-59424 or JP-A-8-67608. Specifically, first, a silane coupling agent having two or more hydroxyl groups directly bonded to a silicon atom is produced. The produced silane coupling agent having two or more hydroxyl groups directly bonded to a silicon atom is dropped into a heated and stirred aqueous peptide solution at a basic pH of 9 to 11, and the two are brought into contact with each other, whereby the silane coupling agent bonds to the amino group of the peptide, and a peptide is obtained in which a silyl functional group having two or more hydroxyl groups is bonded to a silicon atom as shown in the general formula (III) above.

A silane coupling agent having two or more hydroxyl groups directly bonded to a silicon atom can be produced, for example, by stirring a silane coupling agent having an alkoxy group directly bonded to a silicon atom in an acidic or basic aqueous solution at 30 to 50°C for about 5 to 20 minutes to convert the alkoxy group directly bonded to the silicon atom into a hydroxyl group. However, when a silane coupling agent having an alkoxy group directly bonded to a silicon atom is dropped into a solution having a pH range of 9 to 11 in which the silane coupling agent and peptide are reacted, the alkoxy group is hydrolyzed and converted into a hydroxyl group. In other words, it is not necessary to hydrolyze the silane coupling agent having an alkoxy group in advance, and this can be done by directly adding the silane coupling agent having an alkoxy group to an aqueous peptide solution with a pH of 9 to 11.

Specific examples of silylated peptides include N-[2-hydroxy-3-(3'-trihydroxysilyl)propoxy]propyl hydrolyzed protein, N-[2-hydroxy-3-(3'-dihydroxymethylsilyl)propoxy]propyl hydrolyzed protein, N-(3-trihydroxysilyl)propyl hydrolyzed protein, N-(3-dihydroxymethylsilyl)propyl hydrolyzed protein, etc. There are no particular limitations on the peptides used to produce silylated peptides as long as they are used in cosmetics, but hydrolyzed proteins are preferred. Hydrolyzed proteins are peptides obtained by partially hydrolyzing proteins with acids, alkalis, enzymes, or a combination thereof, and examples of the protein sources include animal proteins, vegetable proteins, and proteins derived from microorganisms. Examples of animal proteins include collagen (including its denatured form, gelatin), keratin, silk proteins (fibroin or sericin), casein, conchiolin, elastin, protamine, egg yolk proteins and egg white proteins from chickens, and examples of vegetable proteins include proteins contained in soybeans, wheat, rice (rice bran), sesame, peas, corn, potatoes, etc. Examples of proteins derived from microorganisms include yeast fungi of the genera Saccharomyces, Candida, and Endomycopsis, yeast proteins isolated from yeast fungi known as brewer's yeast and sake yeast, proteins isolated from mushrooms (basidiomycetes) and Chlorella, and spirulina proteins derived from seaweed, but are not limited thereto. Furthermore, the number average molecular weight of the hydrolyzed protein is preferably 100 to 50,000, and more preferably 200 to 5,000.

From the viewpoint of industrial availability, silylated hydrolyzed silk protein is preferred as the silylated peptide of the silylated peptide/silane compound copolymer that constitutes the wall material of the UV absorber-encapsulated microcapsules.

The silylated amino acid can be produced by the production method described in JP 2017-132713 A or JP 2017-218392 A. Specifically, first, a silane coupling agent having two or more hydroxyl groups directly bonded to a silicon atom is produced. The produced silane coupling agent having two or more hydroxyl groups directly bonded to a silicon atom is dropped into an aqueous solution of an α-amino acid that is heated and stirred under a basic condition of pH 9 to 11, and the two are brought into contact with each other, whereby the silane coupling agent is bonded to the amino group of the α-amino acid, and an amino acid having a silyl functional group having two or more hydroxyl groups bonded to a silicon atom as shown in the general formula (III) is obtained. In the case of an α-amino acid having an amino group other than an α-amino acid (basic amino acid, for example, lysine), the amino group that reacts with the silane coupling agent may be either the α-amino group or the other amino group.

A silane coupling agent having two or more hydroxyl groups directly bonded to a silicon atom can be produced, for example, by stirring a silane coupling agent having an alkoxy group directly bonded to a silicon atom in an acidic or basic aqueous solution at 30 to 50°C for about 5 to 20 minutes to convert the alkoxy group directly bonded to the silicon atom into a hydroxyl group. However, when a silane coupling agent having an alkoxy group directly bonded to a silicon atom is dropped into a solution having a pH range of 9 to 11 in which the silane coupling agent and an amino acid are reacted, the alkoxy group is hydrolyzed and converted into a hydroxyl group. In other words, it is not necessary to hydrolyze the silane coupling agent having an alkoxy group in advance, and this can be done by directly adding the silane coupling agent having an alkoxy group to an aqueous amino acid solution with a pH of 9 to 11.

Specific examples of silylated amino acids include N-[2-hydroxy-3-(3'-trihydroxysilyl)propoxy]propyl amino acid, N-[2-hydroxy-3-(3'-dihydroxymethylsilyl)propoxy]propyl amino acid, N-(3-trihydroxysilyl)propyl amino acid, and N-(3-dihydroxymethylsilyl)propyl amino acid. There are no particular limitations on the α-amino acids used in the production of silylated amino acids, so long as they are used in cosmetics. For example, any of the following can be used: acidic amino acids such as aspartic acid and glutamic acid; neutral amino acids such as glycine, alanine, serine, threonine, methionine, cysteine, valine, leucine, isoleucine, phenylalanine, tyrosine, proline, hydroxyproline, tryptophan, asparagine, and glutamine; and basic amino acids such as arginine, lysine, histidine, and ornithine.

The α-amino acids constituting the silylated amino acids are preferably hydrophilic amino acids, and therefore, as silylated amino acids, those having both hydrophobic and hydrophilic parts are preferred. Here, hydrophilic amino acids refer to those having a solubility of 10% or more in water at 25°C, and examples thereof include aspartic acid, glutamic acid, glycine, alanine, serine, and proline. Among hydrophilic amino acids, neutral amino acids that do not have a charge are more preferred, since they are easily incorporated into the dispersed phase and provide stronger capsules with superior stability. In other words, neutral amino acids such as serine, glycine, alanine, and proline are more preferred.

The α-amino acid used in the reaction may be one type of amino acid or a mixture of two or more types of amino acids. However, because the reactivity with silane coupling agents may differ depending on the amino acid, a mixture of amino acids will lead to a decrease in the reaction rate of producing the silylated amino acid that forms the capsule wall membrane. For this reason, when producing silylated amino acids, it is desirable to silylate using one type of amino acid and then mix them when preparing the microcapsules.

From the viewpoint of industrial availability, silylated hydrolyzed serine is preferred as the silylated amino acid of the silylated amino acid-silane compound copolymer that constitutes the wall material of the microcapsules containing an ultraviolet absorber.

Silane compounds to be copolymerized with silylated peptides or silylated amino acids include, for example, tetramethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, n-propyltrimethoxysilane, diisopropyldimethoxysilane, isobutyltrimethoxysilane, diisobutyldimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, octadecyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, octyltriethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, hexyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, and diphenyldichlorosilane.

Microcapsules containing an ultraviolet absorber and having a wall made of a copolymer of a silylated peptide and a silane compound can be produced by the methods described in Patent Document 1 and Patent Document 2. Specifically, an aqueous solution of a silylated peptide or a silylated amino acid is adjusted to pH 1 to 5, preferably pH 2 to 4, and a silane compound represented by general formula (IV) is added while stirring at 100 to 400 rpm, preferably 200 to 300 rpm, in the range of -5°C to 90°C, preferably 5°C to 75°C, more preferably 40 to 60°C. After the addition is completed, the mixture is further stirred at 40 to 60°C to react, and the pH is adjusted to about 5 to 7 to obtain a prepolymer. Examples of acidic agents used for pH adjustment include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, and organic acids such as acetic acid. Examples of alkaline agents include sodium hydroxide and potassium hydroxide.

Next, while stirring the dispersion containing the prepolymer prepared above at 500 to 700 rpm, preferably about 550 to 650 rpm, the UV absorber to be the core substance to be encapsulated or a solution of the UV absorber dissolved in a liquid oily substance is added over a period of 30 minutes to 3 hours at 30 to 70°C, preferably 45 to 55°C. After the addition is complete, the dispersion is stirred in a homomixer at 5,000 to 15,000 rpm, preferably 8,000 to 12,000 rpm, for an additional 2 to 5 hours to thoroughly emulsify and form a wall membrane.

Although encapsulated microcapsules can be obtained as described above, there is a possibility that hydroxyl groups remain in the silane compound condensate that constitutes the wall membrane. If hydroxyl groups remain, the hydroxyl groups on the capsule surface may bond with each other, causing the capsules to aggregate and precipitate. Therefore, it is preferable to subject the encapsulated microcapsules obtained as described above to a capsule surface treatment to prevent aggregation.

Surface treatments such as capsule wall hardening and aggregation prevention can be carried out by adding a silane compound for surface treatment, which has been hydrolyzed in advance to generate hydroxyl groups, to a dispersion liquid containing capsules, or by adjusting the pH of the dispersion liquid containing capsules to a level at which the silane compound used for surface treatment is hydrolyzed, and then adding the silane compound to the dispersion liquid. That is, the pH of the dispersion liquid containing capsules is adjusted to 2-4, and the silane compound is added while stirring at 300-800 rpm, preferably at a temperature in the range of 40°C to 75°C. After the addition is complete, stirring is continued for a further 2-5 hours to allow the reaction to proceed sufficiently.

Examples of silane compounds that can be used for surface treatment include trimethylsilyl chloride (trimethylchlorosilane), triethylsilyl chloride (triethylchlorosilane), t-butyldimethylsilyl chloride (t-butyldimethylchlorosilane), triisopropylsilyl chloride (triisopropylchlorosilane), trimethylethoxysilane, and triphenylethoxysilane.

When the constituent monomers of the above-mentioned silane compound are copolymerized with a silylated peptide or a silylated amino acid to produce a UV absorbent-containing microcapsule having a wall material of a copolymer of a silylated peptide and a silane compound or a copolymer of a silylated amino acid and a silane compound, one or a mixture of two or more types of UV absorbents may be used. The UV absorbent can be encapsulated in the range of 0.01 to 99% by mass of the total mass of the microcapsule, but considering the ease of preparation of the microcapsule and the UV protection effect of the prepared microcapsule, the encapsulation rate of the UV absorbent is preferably 80 to 95% by mass of the total mass of the microcapsule. In other words, if the amount of UV absorbent to be encapsulated is small, the UV protection effect of the UV protector encapsulated in the microcapsule will be low, so if it is incorporated into a cosmetic for UV protection purposes, a large amount must be incorporated, which may impair the feel of the cosmetic. On the other hand, if the encapsulation rate of the UV absorbent is extremely increased, the proportion of the wall material in the total amount of the microcapsule will decrease, and the stability of the microcapsule may decrease.

The ultraviolet absorbers encapsulated in the microcapsules include benzophenone derivatives such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sodium sulfonate, dihydroxydimethoxybenzophenone-sodium sulfonate, 2,4-dihydroxybenzophenone, and tetrahydroxybenzophenone; paraaminobenzoic acid derivatives such as paraaminobenzoic acid, ethyl paraaminobenzoate, glyceryl paraaminobenzoate, amyl paradimethylaminobenzoate, and octyl paradimethylaminobenzoate; ethyl paramethoxycinnamate, isopropyl paramethoxycinnamate, 2-ethylhexyl paramethoxycinnamate (ethylhexyl methoxycinnamate), sodium paramethoxycinnamate, potassium paramethoxycinnamate, and glyceryl di-paramethoxycinnamate mono-2-ethylhexanoate. methoxycinnamic acid derivatives such as octyl salicylate, phenyl salicylate, homomenthyl salicylate, dipropylene glycol salicylate, ethylene glycol salicylate, myristyl salicylate, salicylic acid derivatives such as methyl salicylate, urocanic acid, ethyl urocanate, 4-tert-butyl-4'-methoxydibenzoylmethane (t-butyl methoxydibenzoylmethane), 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, methyl anthranilate, octocrylene (2-cyano-3,3-diphenylprop-2-enoate-2-ethylhexyl), 2-(4-diethylamino-2-hydroxybenzoyl)hexyl benzoate (diethylamino hydroxybenzoyl hexyl benzoate), bisethylhexyloxyphenol methoxyphenyl triazine, and octyl triazone. Among these, 2-ethylhexyl paramethoxycinnamate, 4-tert-butyl-4'-methoxydibenzoylmethane, octocrylene, and 2-(4-diethylamino-2-hydroxybenzoyl)hexyl benzoate are preferably used. However, they are not limited to the above examples. In addition, the encapsulated substance may contain other components besides the ultraviolet absorber as long as the purpose of the present invention is not impaired.

Commercially available products of such UV absorber-containing microcapsules include Silasoma ME (polysilicone-14, ethylhexyl methoxycinnamate, water), Silasoma MEA (polysilicone-14, ethylhexyl methoxycinnamate, t-butyl methoxydibenzoylmethane, water), Silasoma REA(S) (polysilicone-14, octocrylene, t-butyl methoxydibenzoylmethane, water), Silasoma EP(S) (polysilicone-14, ethylhexyl methoxycinnamate, diethylamino hydroxybenzoyl hexyl benzoate, water), and Silasoma SP (polysilicone-35, ethylhexyl methoxycinnamate, diethylamino hydroxybenzoyl hexyl benzoate, water), all manufactured by Seiwa Kasei Co., Ltd.

The ultraviolet absorbent encapsulated in the ultraviolet absorbent-encapsulated microcapsules having a wall membrane made of a copolymer of a silylated peptide and a silane compound or the ultraviolet absorbent-encapsulated microcapsules having a wall membrane made of a copolymer of a silylated amino acid and a silane compound may be encapsulated in one type or in a mixture of two or more types.

The content of the microcapsules containing an ultraviolet absorbing agent (A) in the topical skin preparation of the present invention is preferably 0.5 to 30% by mass, and more preferably 1 to 20% by mass, based on the total mass of the topical skin preparation. If the content of component (A) is less than this, it may not be possible to fully exert its effect as an ultraviolet protection component, and if the content is greater than this, there is a risk of the capsules agglomerating or settling.

[Aqueous thickener]
The thickener of component (B) contained in the skin topical preparation of the present invention is an aqueous thickener selected from an acrylamide compound, a composition containing a nonionic surfactant and a hydrocarbon oil, a bisstearyl PEG/PPG-8/6 (SMDI/PEG-400) copolymer, and xanthan gum. By containing these specific thickeners, it is possible to suppress aggregation of the microcapsules containing the ultraviolet absorber of component (A) and decrease in viscosity of the preparation over time, and when applied to the skin, the preparation exhibits a favorable feel in use, such as low stickiness and good skin compatibility.

The acrylamide-based compound in the composition containing an acrylamide-based compound, a nonionic surfactant, and a hydrocarbon oil includes polyacrylamide and acrylamide copolymers, and the acrylamide copolymers include copolymers containing acrylamide and/or acryloyldimethyltaurine as constituent units.

Specific examples of acrylamide compounds include polyacrylamide, (sodium acrylate/sodium acryloyldimethyltaurate) copolymer, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymer, (acrylamide/ammonium acrylate) copolymer, (acrylamide/sodium acryloyldimethyltaurate) copolymer, polyacrylate-13 (a copolymer of acrylic acid, acrylic acid amide, sodium acrylate, and sodium acryloyldimethyltaurate), and among these, (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymer and polyacrylate-13 are preferably used.

Examples of nonionic surfactants include fatty acid esters of polyhydric alcohols such as glycerin fatty acid esters and their polyalkylene glycol adducts, polyglycerin fatty acid esters and their polyalkylene glycol adducts, propylene glycol fatty acid esters and their polyalkylene glycol adducts, sorbitan fatty acid esters and their polyalkylene glycol adducts, fatty acid esters of sorbitol and their polyalkylene glycol adducts, polyalkylene glycol fatty acid esters such as polyethylene glycol fatty acid esters, sucrose fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyethylene alkyl ether phosphates, alkyl ethers of polyhydric alcohols such as glycerin alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene hydrogenated castor oil, alkylene glycol adducts of lanolin, polyoxyalkylene alkyl co-modified silicones, polyether modified silicones, and alkyl polyglucosides.

Of these, polyoxyalkylene alkyl ethers and polyalkylene glycol adducts of sorbitan fatty acid esters are preferably used, with laureth-7, PEG-7 trimethylolpropane coconut oil alkyl ether, polysorbate 20, polysorbate 60, and polysorbate 80 being particularly preferred.

Examples of hydrocarbon oils include (C13-15) alkanes, (C15-19) alkanes, (C18-21) alkanes, (C21-28) alkanes, (C10,11) isoparaffin, (C10-13) isoparaffin, (C13,14) isoparaffin, (C13-16) isoparaffin, isododecane, isohexadecane, liquid paraffin, heavy liquid isoparaffin, α-olefin oligomers, squalane, polyisobutene, polybutene, etc., among which (C13,14) isoparaffin, squalane, isohexadecane, and polyisobutene are preferably used.

The content of the acrylamide compound in a composition containing an acrylamide compound, a nonionic surfactant, and a hydrocarbon oil is preferably 20 to 80 mass % and more preferably 35 to 70 mass % based on the total amount of the composition.

The content of the nonionic surfactant in the above composition is preferably 0.5 to 15% by mass, and more preferably 2 to 10% by mass, based on the total amount of the composition.

The content of the hydrocarbon oil in the above composition is preferably 10 to 50 mass % of the total amount of the composition, and more preferably 20 to 35 mass %.

Commercially available compositions containing such acrylamide compounds, nonionic surfactants and hydrocarbon oils can be used. For example, SEPIGEL 305 (polyacrylamide, (C13,14) isoparaffin, laureth-7, water), SIMULGEL EG QD ((sodium acrylate/sodium acryloyldimethyl taurate) copolymer, isohexadecane, polysorbate 80, water), SIMULGEL FL ((hydroxyethyl acrylate/sodium acryloyldimethyl taurate) copolymer, isohexadecane, polysorbate 60, water), SIMULGEL NS ((hydroxyethyl acrylate/sodium acryloyldimethyl taurate) copolymer, squalane, polysorbate 60, water), SEPIPLUS S ((hydroxyethyl acrylate/sodium acryloyldimethyl taurate) copolymer, polyisobutene, PEG-7 trimethylolpropane coconut oil alkyl ether, water), and SEPIPLUS Examples of usable agents include 265 (acrylamide/ammonium acrylate copolymer, polyisobutene, polysorbate 20, water), SIMULGEL 600 (acrylamide/sodium acryloyldimethyltaurate copolymer, isohexadecane, polysorbate 80, water), and SEPIPLUS 400 (polyacrylate-13, polyisobutene, polysorbate 20, water).

Among the above compositions, it is preferable to use a composition containing (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymer, polyisobutene, and PEG-7 trimethylolpropane coconut oil alkyl ether, or a composition containing polyacrylate-13, polyisobutene, and polysorbate 20, in terms of the stability of the topical skin preparation of the present invention and the high dispersibility of the microcapsules containing an ultraviolet absorber.

Any commercially available products can be used as the aqueous thickener of component (B) other than the composition containing the acrylamide compound, nonionic surfactant, and hydrocarbon oil. For example, Akpec HU C2002 (bisstearyl PEG/PPG-8/6 (SMDI/PEG-400) copolymer manufactured by Sumitomo Seika Chemicals Co., Ltd., and Labolgum GS-C (xanthan gum) manufactured by DSP Gokyo Food & Chemical Co., Ltd. can be used.

The content of the aqueous thickener of component (B) in the topical skin preparation of the present invention is preferably 0.1 to 5 mass% of the total amount of the topical skin preparation, and more preferably 0.5 to 3 mass%. If the content of component (B) is less than this, the dispersibility of the microcapsules encapsulating the UV absorber may be insufficient, and if it is more than this, the feeling of use may be impaired when applied to the skin, such as stickiness or poor compatibility with the skin.

The topical skin preparation of the present invention may contain water in addition to the above-mentioned components (A) and (B). Furthermore, as long as the effect and stability of the topical skin preparation are not impaired, a wide range of other ingredients that are typically used in topical skin preparations may be blended depending on the application.

In addition to the above-mentioned components (A) and (B) and water, other components that are typically used in topical skin preparations may be appropriately blended, such as oils, solid or semi-solid oils, surfactants, polymeric compounds, moisturizers, whitening agents, texture improvers, drugs, UV absorbers that are not encapsulated in the microcapsules of component (A), proteins, protein hydrolysates or derivatives thereof, amino acids or derivatives thereof, antioxidants, sequestering agents, pH adjusters, preservatives, pigments, colorants, fragrances, etc.

There are no particular limitations on the oil agent, and any oil agent that is liquid at 25°C and is normally used in cosmetics can be used. Examples of oil agents include hydrocarbon oils, oils and fats, ester oils, fatty acids, triacylglycerols, higher alcohols, silicone oils, fluorine-based oils, and lanolin derivatives, regardless of whether they are volatile or non-volatile, and regardless of their origin (animal oil, vegetable oil, synthetic oil, etc.). Specifically, for example, hydrocarbon oils such as (C13-15) alkanes, (C15-19) alkanes, (C18-21) alkanes, (C21-28) alkanes, liquid paraffin, heavy liquid isoparaffin, α-olefin oligomers, squalane, polyisobutylene, polybutene, etc., and the hydrocarbon oils exemplified as those contained in the composition of component (B) above; oils and fats such as olive oil, castor oil, macadamia nut oil, etc.; jojoba oil, diisobutyl adipate, 2-hexyldecyl adipate, di-2-heptylundecyl adipate, alkyl glycol monoisostearate, isocetyl isostearate, trimethylolpropane triisostearate, ethylene glycol di-2-ethylhexanoate, cetyl 2-ethylhexanoate, di-2-ethylhexanoate Neopentyl glycol, trimethylolpropane tri-2-ethylhexanoate, pentaerythritol tetra-2-ethylhexanoate, cetyl 2-ethylhexanoate, oleyl oleate, octyldodecyl oleate, decyl oleate, neopentyl glycol dicaprate, triethyl citrate, 2-ethylhexyl succinate, isocetyl stearate, butyl stearate, diisopropyl sebacate, di-2-ethylhexyl sebacate, cetyl lactate, myristyl lactate, isopropyl palmitate, 2-ethylhexyl palmitate, 2-hexyldecyl palmitate, 2-heptylundecyl palmitate, dipentaerythritol fatty acid esters, isononyl isononanoate, isotridecyl isononanoate, isopropyl myristate, Ester oils such as isopropyl palmitate, 2-octyldodecyl myristate, 2-hexyldecyl myristate, myristyl myristate, hexyldecyl dimethyloctanoate, ethyl laurate, hexyl laurate, 2-ethylhexyl methoxycinnamate, and diisostearyl malate; triglycerides such as glyceryl triisooctanoate, glyceryl triisostearate, diglyceryl diisostearate, diglyceryl triisostearate, diglyceryl tetraisostearate, decaglyceryl decaisostearate, glyceryl triisopalmitate, glyceryl trimyristate, diglyceryl myristate isostearate, tritridecyl trimellitate, and tri(caprylic/capric)glyceryl; N-lauroyl Examples of such oils include amino acid-based oils such as 2-octyldodecyl-L-glutamate and di(phytostearyl-2-octyldodecyl) N-lauroyl-L-glutamate; fatty acids such as isostearic acid and oleic acid; higher alcohols such as oleyl alcohol and isostearyl alcohol; cyclic silicone oils such as cyclotetrasiloxane, cyclopentasiloxane, and cyclohexasiloxane; chain silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, alkoxy-modified organopolysiloxane, and fluorine-modified silicone; fluorine-based oils such as perfluoropolyether; and lanolin derivatives such as lanolin, lanolin acetate, lanolin fatty acid isopropyl, and lanolin alcohol. These can be used alone or in combination of two or more.

Examples of solid or semi-solid oils include fats and oils, such as Theobroma grandiflorum seed fat, mango seed fat, cacao butter, palm oil, palm kernel oil, coconut oil, shea butter, Shorea stenoptera fat, African mango kernel fat, avocado fat, sal seed fat, Astrocaryum murumuru fat, Astrocaryum murumuru seed fat, Astrocaryum tucuma seed fat, Garcinia indica seed fat, Tritilia emetica seed fat, Bassia latifolia seed fat, Garcinia indica seed fat, hydrogenated cacao butter, (macadamia seed oil/hydrogenated macadamia seed oil) esters, and milk fat.

Examples of surfactants include anionic surfactants such as higher fatty acid soaps, polyoxyethylene alkyl ether sulfates, acyl-N-methyl taurine salts, N-acyl amino acid salts, and alkyl phosphate ester salts; cationic surfactants such as alkyl trimethyl ammonium chloride, dialkyl dimethyl ammonium chloride, and fatty acid amido alkyl amines; amphoteric surfactants such as alkyl dimethyl amino acetate betaine, alkyl amido amino acetate betaine, and 2-alkyl-N-carboxy-N-hydroxy imidazolinium betaine; polyglycerin fatty acid esters, polyoxyalkylene glycol fatty acid esters, sorbitan fatty acid esters, sorbitol fatty acid esters, polyoxyalkylene alkyl ethers, polyether modified silicones, and alkyl polyglucosides; and nonionic surfactants exemplified as those contained in the composition of component (B).

Examples of polymeric compounds include carboxyvinyl polymers, sodium carboxymethylcellulose, polyvinyl alcohol, polymeric dimethylpolysiloxane, gum arabic, tragacanth gum, carbro gum, guar gum, pectin, agar, quince seed, starch, algae colloid, dextran, succinoglucan, collagen, gelatin, casein, albumin, carboxymethyl starch, methylcellulose, ethylcellulose, methylhydroxypropylcellulose, carboxymethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, nitrocellulose, sodium cellulose sulfate, sodium carboxymethylcellulose, sodium alginate, polyvinyl methyl ether, sodium polyacrylate, polyethylene acrylate and other acrylic acid-based compounds, cationic polymers, and the acrylamide-based compounds exemplified as those contained in the composition of component (B) above.

Examples of the acrylic acid-based compounds include (acrylic acid/acryloyldimethyltaurate/dimethylacrylamide) crosspolymer, (ammonium acryloyldimethyltaurate/vinylpyrrolidone) copolymer, (ammonium acryloyldimethyltaurate/beheneth-25 methacrylate) crosspolymer, (ammonium acryloyldimethyltaurate/steareth-25 methacrylate) crosspolymer, sodium polyacrylate, polyethylene acrylate, polyacrylate crosspolymer-6, (acrylamidopropyltrimonium chloride/acrylates) copolymer, (acrylates/alkyl acrylate (C10-30)) crosspolymer, (acrylates/steareth-20 methacrylate) copolymer, (acrylates/beheneth-25 methacrylate) copolymer, (acrylates/steareth-20 itaconate) copolymer, steareth-10 allyl ether/acrylates copolymer, and carboxyvinyl polymer.

Examples of moisturizing agents include glycerin, propylene glycol, maltitol, sorbitol, 1,3-butylene glycol, sodium lactate, polyethylene glycol, sodium pyrrolidone carboxylate, and sodium hyaluronate.

Examples of whitening agents include ellagic acid, chamomile extract, licorice extract, rucinol, rosemary extract, arbutin, tranexamic acid, potassium 4-methoxysalicylic acid, ascorbic acid, ascorbic acid glucoside, and ascorbic acid derivatives such as magnesium ascorbyl phosphate.

Texture improvers include amylopectin (amylose), acylated amino acids, polymethylmethacrylate, boron nitride, silica, alumina, aluminum hydroxide, metal soap, silicone powder, polymethylmethacrylate, and dimethylsilylated silica.

Examples of the drug include skin roughness prevention agents and anti-inflammatory agents. Examples of skin roughness prevention agents and anti-inflammatory agents include dipotassium glycyrrhizinate, stearyl glycyrrhetinate, methyl salicylate, pyridoxine hydrochloride, allantoin, sea salt, mulberry bark extract, aloe extract, gardenia extract, chamomile extract, licorice extract, soapberry extract, apricot kernel extract, scutellaria extract, sweet tea extract, loquat extract, ginkgo extract, hypericum extract, yarrow extract, safflower extract, spruce extract, salvia extract, white birch extract, chinpi extract, and peach kernel extract. , Gaiyou extract, Althea extract, Arnica extract, Carrot extract, Peony extract, Cnidium extract, Gentian extract, Cordyceps sinensis extract, Phellodendron bark extract, Inchinko extract, Geranium herb extract, Peach leaf extract, Kumazasa extract, Coix seed extract, Horse chestnut extract, Hawthorn extract, Coptis japonica extract, Ganoderma lucidum extract, Calendula officinalis extract, Peppermint extract, Comfrey extract, Butcher's broom extract, Malva sylvestris extract, Centaurea cyanus extract, and Togenashi extract. Other examples of drugs include hair growth drugs, acne drugs, dandruff and itching drugs, and drugs to prevent underarm odor.

As the ultraviolet absorber not encapsulated in the microcapsules of component (A), an ultraviolet absorber encapsulated in the microcapsules may be used, and specific examples include those exemplified as ultraviolet absorbers encapsulated in the microcapsules of component (A).

Examples of proteins, protein hydrolysates, and derivatives thereof include milk protein, silk protein, wheat protein, rice protein, pea protein, collagen, keratin, soybean, sesame, conchiolin, marine collagen, and other proteins, as well as their hydrolysates or acylated, silylated, cationized, and alkyl ester derivatives of protein hydrolysates.

Examples of amino acids or derivatives thereof include amino acids such as glycine, alanine, valine, leucine, isoleucine, serine, threonine, phenylalanine, arginine, lysine, asparagine, aspartic acid, glutamine, glutamic acid, cystine, cysteine, methionine, tryptophan, proline, and histidine, as well as acylated, alkylated, glycerylated, and esterified derivatives thereof.

Examples of antioxidants include sodium pyrosulfite, vitamin E or its derivatives, tannin, and BHT (butylhydroxytoluene).

Examples of sequestering agents include sodium edetate, phosphoric acid, etidronic acid, etc.

Examples of pH adjusters include lactic acid, citric acid, glycolic acid, succinic acid, tartaric acid, malic acid, potassium carbonate, sodium bicarbonate, and ammonium bicarbonate.

Examples of preservatives include 1,2-alkanediols such as 1,2-pentanediol and 1,2-hexanediol, paraoxybenzoic acid alkyl esters such as methylparaben and propylparaben, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, phenoxyethanol, and ethylhexylglycerin.
The above-mentioned components usually used in cosmetics can be used alone or in combination of two or more kinds.

The skin topical preparation of the present invention can be suitably used in various formulations, such as cream, emulsion, gel, and liquid. As for the product form, it can be used as a skin care topical preparation including a sunscreen cosmetic, or as a makeup cosmetic such as a base or foundation having a sunscreen effect.

The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. Note that all values shown in the tables of the examples are in mass % relative to the total mass of the topical skin preparation.

Examples 1 to 8 and Comparative Examples 1 to 4: Microcapsule aqueous dispersions containing ultraviolet absorbers After mixing the aqueous thickeners and water shown in Tables 1 and 2, microcapsules containing ultraviolet absorbers (Silasoma MEA manufactured by Seiwa Kasei Co., Ltd.) were added, and the mixture was stirred with a disper (1500 rpm) to prepare aqueous dispersions of microcapsules containing ultraviolet absorbers.

[Evaluation of stability and dispersibility]
The above-prepared aqueous dispersion of UV absorber-encapsulating microcapsules was stored in thermostatic chambers at 25°C and 50°C for 4 weeks, and the stability and capsule dispersibility were evaluated according to the following evaluation criteria. Viscosity was measured using a Brookfield LVT viscometer. The results are shown in Tables 1 and 2.
Stability:
◯: Viscosity change was within ±20% compared to immediately after preparation.
Δ: Viscosity change was ±20% or more compared to immediately after preparation.
×: Capsule aggregation or precipitation was observed.
Dispersibility:
Good: The capsules were evenly dispersed.
△: Some capsules tended to aggregate and grow larger.
×: Capsule aggregation or precipitation was observed.

In Table 1, *1 indicates Silasoma MEA (product name, manufactured by Seiwa Kasei Co., Ltd.) (containing 60% by mass of microcapsules with polysilicone-14 as the wall material and ethylhexyl methoxycinnamate and t-butyl methoxydibenzoylmethane encapsulated therein, and 40% by mass of water).
*2 is SEPIGEL 305, *3 is SEPIGEL EG QD, *4 is SIMULGEL NS, *5 is SEPIPLUS S, *6 is SEPIPLUS 400, and *7 is SIMULGEL FL (all trade names, all manufactured by SEPPIC).
*8 is Labolgum GS-C (product name) manufactured by DSP Gokyo Food & Chemical Co., Ltd., and *9 is Akupec HU C2002 (product name) manufactured by Sumitomo Seika Chemicals Co., Ltd.

From the results shown in Tables 1 and 2, it was clear that the UV absorber-encapsulated microcapsule aqueous dispersions of Examples 1 to 8, which contained a composition containing an acrylamide compound, a nonionic surfactant, and a hydrocarbon oil, and bisstearyl PEG/PPG-8/6 (SMDI/PEG-400) copolymer or xanthan gum as a thickener, were superior in stability and dispersibility compared to Comparative Examples 1 to 3, which contained other thickeners. Also, it was clear that the stability and capsule dispersibility were superior to those of Comparative Example 4, which contained only an acrylamide compound as a thickener, when a composition containing the same acrylamide compound, a nonionic surfactant, and a hydrocarbon oil was used.

Examples 9 and 10: Aqueous gel The components (A) shown in Table 3 were mixed, and then the components (B) were added and stirred with a disper (2000 rpm) for 3 minutes. In Example 9, the components (C) were then added and stirred with a disper (4000 rpm) for 1 minute. The components (D) were further added and stirred with a disper (3000 rpm) for 1 minute to prepare an aqueous gel. The stability and dispersibility of the prepared aqueous gel were evaluated in the same manner as in Examples 1 to 8 and Comparative Examples 1 to 4.

In Table 3, *1 and *5 are the same as in Table 1. *11 was blended as euxyl PE9010 (trade name) manufactured by Schulke & Meyer.
*12 is SEPIFINE BB (product name) manufactured by SEPPIC Corporation.

As shown in the results in Table 3, it was clear that the aqueous gels prepared in Examples 9 and 10 had excellent stability and capsule dispersibility.

Claims (1)

(A) a structural unit U represented by the following general formula (Ia), (Ib) or (Ic):

[In the formula, R ² represents an alkyl group having 1 to 20 carbon atoms, and each R ² may be the same or different.]
and a structural unit W represented by the following general formula (Id) or (Ie):

(wherein R ¹ represents an alkyl group having 1 to 3 carbon atoms, each R ¹ may be the same or different, A represents a divalent group bonding Si and N, and represents at least one group selected from the group consisting of -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, *-(CH ₂ ) ₃ OCH ₂ CH(OH)CH ₂ -, and *-(CH ₂ ) ₃ OCOCH ₂ CH ₂ - (* represents the side bonding to Si), and E represents a residue obtained by removing one primary amino group from a polypeptide or α-amino acid having a number average molecular weight of 100 to 50,000), and (B) an encapsulated microcapsule having a wall membrane made of a silylated peptide/silane compound copolymer or a silylated amino acid/silane compound copolymer, the copolymer having the formula: An aqueous thickener which is a composition containing an acrylamide compound selected from (hydroxyethyl acrylate/sodium acryloyldimethyltaurate) copolymer and polyacrylate-13, a nonionic surfactant, and a hydrocarbon oil.
A skin topical preparation comprising: