JP7237463B2 - Pickering emulsion containing acrylic polymer - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies May 23, 2018 Orbis The Shop Ikebukuro Marui store and other stores nationwide Disclosure

Application of Article 30, Paragraph 2 of the Patent Act May 23, 2018 Disclosure through online sales

Application of Article 30, Paragraph 2 of the Patent Act Published on the Internet on May 23, 2018

Application of Article 30, Paragraph 2 of the Patent Law May 16, 2018 Disclosure by press release on the Internet

The present invention relates to Pickering emulsions.

A dosage form emulsified by adsorbing amphipathic solid particles to the interface is conventionally known as a Pickering emulsion, and its use in cosmetics has also been proposed. For example, titanium dioxide, zinc oxide, etc. have been proposed as the solid particles, and it has been proposed to use these solid particles whose surfaces have been hydrophobized for the preparation of Pickering emulsions (Patent Document 1). An oil-in-water emulsion using partially hydrophobized silica has also been proposed, and is said to be good in non-stickiness, freshness, and high-temperature emulsion stability (Patent Document 2).

Japanese Patent Publication No. 2001-518111 JP 2013-129626 A

The Pickering emulsion has a problem that the types and amounts of oils that can be emulsified are limited, and if the limits are exceeded, the emulsified state deteriorates.
The problem to be solved by the present invention is to provide a technique for improving the emulsification stability of a Pickering emulsion. In particular, an object of the present invention is to provide a technology for improving the emulsification stability of a Pickering emulsion that can be applied to a form containing a polar oil as an oil phase component.

As a result of the diligent research efforts of the present inventors, it was found that the addition of an acrylic acid polymer enabled the preparation of a Pickering emulsion with a fine emulsified particle size and excellent stability, in which the dispersion state of the powder adsorbed on the emulsification interface was improved. was done. Based on such knowledge, the present invention was completed.

The present invention for solving the above problems is a Pickering emulsion characterized in that powder is adsorbed on the emulsion interface and contains an acrylic polymer.
The emulsion composition of the present invention is excellent in emulsion stability.

In a preferred embodiment of the present invention, the acrylic polymer is a copolymer containing structural units derived from alkyl (meth)acrylate.

In a preferred form of the invention, the acrylic polymer is an acrylates copolymer.

A preferred embodiment of the present invention contains a polar oil as an oil phase component.
Conventionally, it has been difficult to prepare a stable Pickering emulsion when a polar oil is included as an oil phase component. Application of the present invention can improve the stability of a Pickering emulsion containing a polar oil as an oil phase component.

In a preferred embodiment of the present invention, a highly polar oil having an IOB value of 0.1 or more is included as the polar oil.
Conventionally, Pickering emulsions containing such highly polar oils have poor stability. According to the present invention, it is possible to provide a stable Pickering emulsion even in a form containing such a highly polar oil.

In a preferred embodiment of the present invention, the proportion of the polar oil in the oil contained in the Pickering emulsion is 60% by mass or more.
In the prior art, it was difficult to stably prepare a Pickering emulsion containing 60% by mass or more of polar oil in the oil. According to the present invention, it is possible to provide a Pickering emulsion having excellent emulsification stability even in a form containing a high content of such polar oil.

A preferred embodiment of the present invention contains an ultraviolet absorber as the polar oil.
According to the present invention, it is possible to improve the emulsification stability of a Pickering emulsion containing an ultraviolet absorber.

In a preferred embodiment of the present invention, the ratio of the ultraviolet absorber to the oil contained in the Pickering emulsion is 30% by mass or more.
According to the present invention, it is possible to provide such a UV absorber-rich Pickering emulsion.

In a preferred form of the present invention, the average emulsified particle size is 15 μm or less.
A Pickering emulsion of such a form is excellent in emulsification stability.

In a preferred form of the present invention, the content of the surfactant other than the powder is 0.1% by mass or less.
Even as a surfactant-free form, the Pickering emulsions of the present invention exhibit excellent emulsion stability.

ADVANTAGE OF THE INVENTION According to this invention, the Pickering emulsion excellent in emulsification stability can be provided.

1 is a microscope image of Pickering emulsions of Example 1 and Comparative Example 2. FIG.

<1> Acrylic polymer The Pickering emulsion of the present invention contains an acrylic polymer as an essential component. The acrylic polymer includes polymers or copolymers whose constituent monomers are (meth)acrylic monomers selected from (meth)acrylic acid and its amides and esters.
In the present invention, it is preferable to use acrylic copolymers that are random copolymers, alternating copolymers or block copolymers.

As the ester of (meth)acrylic acid, a (meth)acrylic acid alkyl ester can be preferably exemplified.
The number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester is not particularly limited, and preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 4 can be exemplified.

When an amide or ester of (meth)acrylic acid is used as a constituent monomer, the amide residue or ester residue may have a substituent.
Substituents may be those derived from biological constituents such as sugar residues, amino acid residues, and phosphorylcholine.

Such monomers can be prepared by known methods. For example, in the case of a sugar residue, a sugar and a halide of a polyhydric alcohol such as chloroethanol are condensed with an alkali in the presence of a catalyst such as silver oxide to introduce a hydroxyethyl group into the anomer. It can be esterified with methacrylic acid to lead to the desired monomer.

In the case of an amino acid residue, acrylic acid or methacrylic acid is introduced into an acid chloride with thionyl chloride or the like, condensed with an amino acid in the presence of an alkali, and an acid amide bond is constructed to obtain a desired amide monomer.

A phospholipid-like structure such as phosphorylcholine is obtained by condensing phosphorylcholine and chloroethanol in the presence of an alkali to form hydroxyethylphosphorylcholine. A desired monomer can be obtained by condensing this with acrylic acid chloride or methacrylic acid chloride in the presence of an alkali.

Specific examples of such (meth)acrylic monomers include n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. , n-hexyl (meth)acrylate, n-octyl (meth)acrylate, cyclohexyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, Tridecyl (meth) acrylate, myristyl (meth) acrylate, pentadecyl (meth) acrylate, palmityl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate , oleyl (meth)acrylate, behenyl (meth)acrylate, (meth)acrylic acid ester having a linear, branched or alicyclic hydrocarbon group; acrylonitrile; acrylamide, diacetone acrylamide, N, N - (meth)acrylamide such as dimethylacrylamide, Nt-butylacrylamide, N-octylacrylamide, Nt-octylacrylamide; ) acrylamide; alkylaminoalkyl (meth)acrylates such as aminoethyl (meth)acrylate, t-butylaminoethyl methacrylate, and methylaminoethyl (meth)acrylate; dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. Dialkylaminoalkyl (meth)acrylate; Dialkylaminoalkyl (meth)acrylamide such as dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide; Tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, ( Esters of cyclic compounds and meth)acrylic acid such as glycidyl methacrylate; (meth)acrylate alkoxyalkyl esters such as ethoxyethyl (meth)acrylate and methoxyethyl (meth)acrylate; polyethylene glycol mono ( Monoesters of polyalkylene glycol and (meth)acrylic acid such as meth)acrylate and polypropylene glycol mono(meth)acrylate; sulfonic acid group-containing (meth)acrylic ester; methacryloyloxy such as (meth)acryloyloxyethyl phosphate Archi Lurinic acid monoester; glyceryl (meth)acrylate, 2-methacryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl phthalate, β-carboxyethyl acrylate, acryloyloxyethyl succinate, 2-(meth)acryloyl Oxyethyltetrahydrophthalic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid; 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate , polyethylene (n = 2 to 50) glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene (n = 2 to 50) glycol di (meth) acrylate, butylene glycol di (meth) acrylate, dipentyl glycol di (Meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, methylenebisacrylamide, bisphenol F EO-modified (n = 2 to 50) di(meth)acrylate, bisphenol A EO-modified (n = 2 to 50) di(meth)acrylate, bisphenol S EO modified (n = 2 to 50) di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane trika Prolactonate tri(meth)acrylate, trimethylolhexane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate , ditrimethylolpropane tetracaprolactonate tetra(meth)acrylate, ditrimethylolethane tetra(meth)acrylate, ditrimethylolbutane tetra(meth)acrylate, ditrimethylolhexanetetra(meth)acrylate, dipentaerythritol penta(meth)acrylate , dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, etc. having two or more ethylenically unsaturated double bonds Examples include (meth)acrylates, etc. be.

As the acrylic polymer, a copolymer obtained by copolymerizing a (meth)acrylic monomer and a constituent monomer other than the (meth)acrylic monomer may be used.
Examples of such constituent monomers include unsaturated monocarboxylic acids such as crotonic acid; aromatic vinyl compounds such as styrene; unsaturated dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid, maleic anhydride, and citraconic acid; monoalkyl esters of unsaturated dicarboxylic acids such as monoalkyl esters, monoalkyl fumarate and monoalkyl itaconic acid; sulfonic acid group-containing monomers include alkenes such as vinylsulfonic acid and (meth)allylsulfonic acid; Sulfonic acid; aromatic vinyl group-containing sulfonic acid such as α-methylstyrene sulfonic acid; primary to tertiary amino group-containing unsaturated compounds such as (meth)allylamine; amino group-containing aromatics such as N,N-dimethylaminostyrene Vinyl compounds; compounds having two or more ethylenically unsaturated double bonds such as divinylbenzene, diisopropylbenzene, and trivinylbenzene; urethane oligomers having two or more ethylenically unsaturated double bonds; ethylenically unsaturated Silicone compounds having two or more double bonds; vinyl acetate, vinyl chloride, vinylpyrrolidone and the like are exemplified.

The acrylic polymer is a copolymer of two or more constituent monomers selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid (C1-C4) alkylate, and methacrylic acid (C1-C4) alkylate. Preferably.
Specifically, a compound denoted as "ACRYLATES COPOLYMER" in the INCI name (International Cosmetic Ingredient Dictionary and Handbook, 14th Edition, Vol. 1, CTFA, 2012, p.60-61) is mentioned.

The acrylic polymer can be obtained by polymerizing the constituent monomers described above.
Polymerization may be carried out according to a conventional method in the presence of a polymerization initiator such as azobisbutyronitrile.

The content of the acrylic polymer is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.05% by mass or more, from the viewpoint of reducing the emulsified particle size of the Pickering emulsion or improving the emulsion stability. It is 0.1% by mass or more, more preferably 0.15% by mass or more, and still more preferably 0.2% by mass or more.

The upper limit of the content of the acrylic polymer relative to the entire Pickering emulsion is not particularly limited, but is preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, further preferably 0.5% by mass or less. 5% by mass or less can be used as a guideline.

<2> Powder In the Pickering emulsion of the present invention, powder is adsorbed to the emulsion interface. As the powder, any powder having emulsifying ability that is usually used for Pickering emulsion can be used without any particular limitation.

As the powder, both organic powder and inorganic powder can be used. In particular, it is preferable to use metal oxide powder in the present invention.
The metal oxides referred to here also include oxides of metalloids such as silicon.
Examples of metal oxide powders include silica, titanium dioxide, zinc oxide, iron oxide, zirconium oxide and cerium oxide.

When silica powder is used as the metal oxide powder, for example, either so-called dry silica powder produced by vapor phase oxidation of a silicon halide or so-called wet silica powder produced from water glass or the like can be used. may be used.
As dry silica powder, for example Aerosil series (Nippon Aerosil Co., Ltd.), CAB-O-SIL series (Cabot Corporation), HDK series (Asahi Kasei Wacker Silicone Co., Ltd.), as wet silica powder, for example Nipsil series (Tosoh Silica Co., Ltd.), HI-SIL series (PPG), and other commercially available products can be used.

As for other metal oxide powders, since there are many commercially available products, the commercially available products can be used as they are. Specific examples of such commercially available products include "MTY-110M3S" (manufactured by Tayca Corporation), "MTY-02" (manufactured by Tayca Corporation), and "MT-100TV" (Tayca Co., Ltd.) as particulate titanium dioxide. company), "MT-500HSA" (manufactured by Tayca Co., Ltd.), "MT-100T" (manufactured by Tayca Co., Ltd.), "MT-01" (manufactured by Tayca Co., Ltd.), "MT-10EX" (manufactured by Tayca Co., Ltd.) ), “MT-05” (manufactured by Tayca Co., Ltd.), “MT-100Z” (manufactured by Tayca Co., Ltd.), “MT-150EX” (manufactured by Tayca Co., Ltd.), “MT-100AQ” (manufactured by Tayca Co., Ltd.), "MT-100WP" (manufactured by Tayca Co., Ltd.), "MT-100SA" (manufactured by Tayca Co., Ltd.), "MT-500B" (manufactured by Tayca Co., Ltd.), "MT-500SA" (manufactured by Tayca Co., Ltd., "MT- 600B" (manufactured by Tayca Co., Ltd.), "MT-500SAS" (manufactured by Tayca Co., Ltd.), ) "Tipaque CR-50" (manufactured by Ishihara Sangyo Co., Ltd.), "Tipaque TTO-M-1" (manufactured by Ishihara Sangyo Co., Ltd. ) “Tipaque TTO-V4” (manufactured by Ishihara Sangyo Co., Ltd.), “ST-455” (manufactured by Titan Kogyo Co., Ltd.), “STT-65C-S” (manufactured by Titan Kogyo Co., Ltd.), “STT-30EHS” (titanium Industrial Co., Ltd.), "Bayer Titanium R-KB-1" (manufactured by Bayer AG), and the like.

In addition, as microparticle zinc oxide, "MZ-300" (manufactured by Tayka Co., Ltd.), "MZY-303S" (manufactured by Tayca Co., Ltd.), "MZ-306X" (manufactured by Tayca Co., Ltd.), "MZ-500" (manufactured by Tayca Co., Ltd.) Co., Ltd.), “MZY-505S” (Tayca Co., Ltd.), “MZ-506X” (Tayca Co., Ltd.), “MZ-510HPSX” (Tayca Co., Ltd.), “WSX-MZ-700” (Tayca Co., Ltd.) Co., Ltd.), “SANT-UFZO-450” (manufactured by Miyoshi Kasei Co., Ltd.), “SANT-UFZO-500” (manufactured by Miyoshi Kasei Co., Ltd.), “FZO-50” (manufactured by Ishihara Sangyo Co., Ltd.), “Max Light ZS-032" (manufactured by Showa Denko K.K.), and "Maxlight ZS-032D" (manufactured by Showa Denko K.K.).

The surface of the metal oxide powder is preferably hydrophobized. Hydrophobized metal oxide powder can be produced by reacting metal oxide powder with a hydrophobizing agent to add hydrophobic groups to hydroxyl groups present on the surface of the powder through covalent bonding. It can be prepared by coating the surface with a hydrophobizing agent by physically adhering it.

The hydrophobizing treatment includes a method of treating the metal oxide powder with a hydrophobizing agent such as an organosilicon compound, silicone, hydrocarbon oil, fatty acid, fatty acid amide, fatty acid ester, higher alcohol, or polyoxyalkylene compound.
Particularly preferably, the metal oxide powder is treated using an organosilicon compound or silicone as a hydrophobizing agent.

Examples of organosilicon compounds include hexamethyldisilazane, monomethylsilane, dimethylsilane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldisilane. Examples include ethoxysilane, hexamethyldisiloxane, palmitylsilane, and the like. These are used singly or as a mixture of two or more.

In a preferred embodiment of the present invention, metal oxide powder is treated with trimethylsilane, and hydrophobized metal oxide powder having a trimethylsilyl group added to the surface is used, and silica powder is particularly preferably treated with trimethylsilane. and partially hydrophobized silica with trimethylsilyl groups attached to the surface is used.

When silicone is used as the hydrophobizing agent, dimethylsilicone, methylphenylsilicone, α-methylstyrene-modified silicone, chlorophenylsilicone, fluorine-modified silicone and the like can be exemplified.

The average primary particle size of the metal oxide powder is not particularly limited. For example, it can be 1 to 1000 nm, preferably 3 to 100 nm, and more preferably 5 to 30 nm.

Also, the average secondary particle size of the metal oxide powder is not particularly limited. It is preferably 1 μm or less, preferably 500 nm or less, more preferably 200 nm or less, still more preferably 50 nm or less.

Here, the average primary particle size and average secondary particle size can be determined by measuring the maximum size of 2500 or more particles on a scanning electron microscope image and calculating the number average.
In addition, the average secondary particle size can be adjusted by the stress applied during the preparation of the composition for external use.

Although the lower limit of the powder content is not particularly limited, it is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more.
The upper limit of the content of the powder is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and still more preferably 2% by mass or less as a guideline. can be done.

<3> Oil phase component

The oil contained in the oil phase in the Pickering emulsion of the present invention is not particularly limited, and may contain liquid oil, solid oil, wax, hydrocarbon oil, higher fatty acid, higher alcohol, ester oil, silicone oil, and the like. .

Examples of liquid oils include avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, sasanqua oil, castor oil, and linseed oil. , safflower oil, cottonseed oil, perilla oil, meadowfoam oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, cinnamon oil, Japanese pear oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, glyceryl triisopalmitate and the like.

Solid oils and fats include cacao butter, coconut oil, horse fat, hydrogenated coconut oil, palm oil, beef tallow, mutton tallow, hydrogenated beef tallow, palm kernel oil, lard, beef bone fat, Japanese wax kernel oil, hydrogenated oil, beef leg fat. , Japanese wax, hydrogenated castor oil and the like.

Waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, wart wax, whale wax, montan wax, bran wax, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugar cane wax, lanolin fatty acid isopropyl, hexyl laurate, reduced lanolin, jojo Barlow, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, POE hydrogenated lanolin alcohol ether and the like.

Hydrocarbon oils include liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax and the like.

Higher fatty acids include, for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, and toric acid.

Examples of higher alcohols include cetyl alcohol, stearyl alcohol, behenyl alcohol, batyl alcohol, myristyl alcohol, and cetostearyl alcohol.

Ester oils include isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, Lanolin acetate, isocetyl stearate, isocetyl isostearate, sucrose stearate, sucrose oleate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, dicaprin Neopentyl glycol acid, diisostearyl malate, glyceryl di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexylate, trimethylolpropane triisostearate, pentaneerythritol tetra-2-ethylhexylate, tri-2- Glyceryl ethylhexylate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glyceryl trimyristate, tri-2-heptyl undecanoic acid glyceride, castor oil fatty acid methyl ester, oleic oil, ceto Stearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, cetyl palmitate, diisobutyl adipate, N-lauroyl-L-glutamic acid 2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, Di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, citric acid triethyl and the like.

Examples of silicone oils include linear polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, diphenylsiloxyphenyltrimethicone, pentasiloxane, decamethylpolysiloxane, dodecamethylpolysiloxane, tetramethyltetrahydro Cyclic polysiloxanes such as genpolysiloxane and the like are included.

Among them, silicone oils, ester oils, liquid fats, solid fats and waxes are preferably used, and diphenylpolysiloxane, cetyl ethylhexanoate and the like are particularly preferably used. 1 type or 2 types or more can be used for an oil agent.

Since the Pickering emulsion of the present invention has excellent emulsion stability, a polar oil can be used as the oil.
Polar oils include vegetable oils such as camellia oil, corn oil, mink oil, olive oil, avocado oil, sasanqua oil, castor oil, jojoba oil, sunflower oil, rapeseed oil, sesame oil, and soybean oil; cetyl 2-ethylhexanoate, myristin monoester oils such as isopropyl acid, cetyl octanoate, octyl palmitate, isocetyl stearate, isopropyl isostearate, octyl isopalmitate, isopropyl sebacate; diethyl sebacate, diisopropyl sebacate, di-2-ethylhexyl sebacate, phthalate Diester oils such as diisopropyl acid; and triester oils such as glyceryl tri-2-ethylhexanoate and tri(caprylic-capric acid)glycerin are particularly preferred.

In addition, it is preferable to use a highly polar oil having an IOB value of 0.1 or more, more preferably 0.2 or more. When using such a highly polar oil, it has been difficult to prepare a stable Pickering emulsion by conventional methods. According to the present invention, a Pickering emulsion having excellent emulsion stability can be prepared even when a highly polar oil is used.

In addition, ultraviolet absorbers generally have a high polarity, making it difficult to prepare a stable Pickering emulsion using them. According to the present invention, a Pickering emulsion excellent in emulsification stability can be prepared even when an ultraviolet absorber is used.

As the ultraviolet absorber, any one used in the field of external skin preparations such as cosmetics can be used without particular limitation. para-aminobenzoic acid ethyl ester, N,N-diethoxy para-aminobenzoic acid ethyl ester, N,N-dimethyl para-aminobenzoic acid ethyl ester, N,N-dimethyl para-aminobenzoic acid butyl ester, N,N-dimethyl para-aminobenzoic acid ethyl ester , diethylaminohydroxybenzoyl hexyl benzoate; anthranilic acid derivatives such as homomenthyl-N-acetylanthranilate; salicylic acid and its sodium salts, amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl Salicylic acid derivatives such as salicylate, p-isopropanol phenyl salicylate; Octyl cinnamate, ethyl-4-isopropyl cinnamate, methyl-2,5-diisopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate, methyl-2,4- Diisopropyl cinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, 2-ethylhexyl p-methoxycinnamate (ethylhexyl methoxycinnamate, octyl para-methoxycinnamate) , 2-ethoxyethyl-p-methoxycinnamate (cinoxate), cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate ( octocrylene), glyceryl mono-2-ethylhexanoyl-diparamethoxycinnamate, cinnamic acid derivatives such as ferulic acid and its derivatives; 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2 ,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone (oxybenzone-3), 2-hydroxy-4-methoxy- 4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenyl- Benzophenone derivatives such as benzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone; 3-(4′-methylbenzylidene)-d,l-camphor, 3- benzylidene-d,l-camphor; 2-phenyl-5-methylbenzoxazole; 2,2′-hydroxy-5-methylphenylbenzotriazole; 2-(2′-hydroxy-5′-t-octylphenyl)benzo Triazole; 2-(2′-hydroxy-5′-methylphenylbenzotriazole; dibenzalazine; dianisoylmethane; 5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one; 4-t- dibenzoylmethane derivatives such as butyl methoxydibenzoylmethane; octyl triazone; urocanic acid derivatives such as urocanic acid and ethyl urocanate; 2-(2′-hydroxy-5′-methylphenyl)benzotriazole, 1-(3, 4-dimethoxyphenyl)-4,4-dimethyl-1,3-pentanedione, hydantoin derivatives such as 2-ethylhexyl dimethoxybenzylidene dioxoimidazolidine propionate; , drometrisol trisiloxane, methyl anthranilate, bisethylhexyloxyphenolmethoxyphenyltriazine, rutin and its derivatives, oryzanol and its derivatives; It is mentioned as a preferable one.

The Pickering emulsions of the present invention are particularly useful in the form containing UVA absorbers as UV absorbers, especially UVA absorbers selected from benzophenone derivatives, dibenzoylmethane derivatives and hydantoin derivatives.
This is because the UVA absorbers have low solubility in oil agents, and have problems such as precipitation especially at low temperatures. According to the present invention, the UVA absorber can be stably contained.

In addition, in the Pickering emulsion of the present invention, it is also preferable to combine a UVA absorbent and a UVB absorbent as UV absorbents from the viewpoint of UV absorption ability. Here, it is particularly preferable to use ethylhexyl methoxycinnamate as the UVB absorber from the viewpoint of improving the stability of the system and the feeling of use.

The proportion of the oil agent in the entire Pickering emulsion is not particularly limited, but in the case of an oil-in-water type Pickering emulsion, it is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% by mass or more. , and more preferably 30% by mass or more.
In the case of an oil-in-water type, the ratio of the oil agent to the whole can be preferably 50% by mass or less, more preferably 40% by mass or less.

In the case of an oil-in-water form, the content of the polar oil in the entire Pickering emulsion is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and still more preferably 25% by mass. % or more.

In the case of an oil-in-water form, the content of the UV absorber in the entire Pickering emulsion is preferably 2% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass, from the viewpoint of UV absorption function. % or more, more preferably 15 mass % or more.

The content of the polar oil in the entire oil phase is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more.

The lower limit of the content of the ultraviolet absorber in the entire oil phase is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and still more preferably, from the viewpoint of improving the ultraviolet absorption function. It is 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, still more preferably 35% by mass or more, and still more preferably 40% by mass or more.

The upper limit of the content of the ultraviolet absorber in the entire oil phase is not particularly limited, and is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and still more preferably 60% by mass or less. , more preferably 50% by mass or less.

<4> Pickering Emulsion The Pickering emulsion of the present invention may be either water-in-oil type or oil-in-water type. An oil-in-water type is preferred.

In the case of an oil-in-water type, the mass ratio of the aqueous phase and the oil phase is not particularly limited, but is preferably 4:6 to 9:1, more preferably 5:5 to 8:2, and still more preferably 5.5. :4.5 to 7:3, more preferably 6:4 to 6.5:3.5.

In the present invention, the mass ratio of the powder to the oil phase is preferably 1:120-3:10, more preferably 1:60-1:5, still more preferably 1:30-1:10.

In the present invention, the mass ratio of the acrylic polymer to the powder is preferably 1:0.5 to 1:100, more preferably 1:1 to 1:50, still more preferably 1:1.5 to 1. :20, more preferably 1:2 to 1:15, more preferably 1:3 to 1:10, more preferably 1:3 to 1:8.
By setting the mass ratio of the acrylic polymer to the powder within the above range, the emulsion stability of the Pickering emulsion can be improved.

The aqueous phase in the Pickering emulsion of the present invention can contain ingredients that are commonly used in cosmetics without particular limitations, but preferably contains the following ingredients, for example.
Polyols include polyethylene glycol, glycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, maltitol, propylene glycol, dipropylene glycol, diglycerin, isoprene glycol, 1,2-pentanediol, 2,4-butylene glycol. Examples include xylene glycol, 1,2-hexanediol, 1,2-octanediol, etc. Among them, glycerin, 1,3-butylene glycol, and sorbitol are preferred. The content of these agents is preferably 0.5 to 20% by mass, more preferably 3 to 10% by mass, based on the entire Pickering emulsion. Also, the content thereof is preferably 3 to 15% by mass, more preferably 5 to 10% by mass of the aqueous phase.
Moreover, it is also preferable to contain a thickener. Thickeners include xanthan gum, gellan gum, guar gum, quince seed, carrageenan, galactan, gum arabic, pectin, mannan, starch, curdlan, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylhydroxypropylcellulose, chondroitin sulfate, dermatan sulfate, glycogen, heparan sulfate, hyaluronic acid, sodium hyaluronate, tragacanth gum, keratan sulfate, chondroitin, mucoitin sulfate, hydroxyethyl guar gum, carboxymethyl guar gum, dextran, kerato sulfate, locust bean gum, succinoglucan, caronin acid, chitin, chitosan, Carboxymethylchitin, agar, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, polyethylene glycol, sodium acrylate grafted starch, stearoxyhydroxypropyl methylcellulose, bentonite and the like, more preferably water-soluble xanthan gum, guar gum and the like. Polysaccharides, agar, sodium acrylate grafted starch, stearoxyhydroxypropyl methylcellulose. Water-soluble polysaccharides such as xanthan gum and guar gum, and agar are more preferred. The content of these is preferably 0.05 to 5% by mass, more preferably 0.1 to 1% by mass of the entire Pickering emulsion. Also, the content of these is preferably 0.1 to 3% by mass, more preferably 0.3 to 1% by mass of the aqueous phase.

The water content in the Pickering emulsion of the present invention is preferably 30 to 80% by mass, more preferably 40 to 70% by mass, particularly preferably 45 to 65% by mass.
Also, the water content is preferably 70 to 90% by mass, more preferably 75 to 85% by mass, relative to the aqueous phase.

From the viewpoint of emulsion stability, the average emulsified particle size of the Pickering emulsion of the present invention is preferably less than 20 µm, more preferably 15 µm or less, even more preferably 10 µm or less, even more preferably 8 µm or less, still more preferably 6 µm or less, and further preferably 6 µm or less. It is preferably 5 μm or less, more preferably 4 μm or less.
The average emulsified particle size can be obtained by observing with an optical microscope at 20° C. and calculating the number average of the maximum diameters of 10 randomly selected emulsified particles.

In the present invention, the average emulsified particle size is preferably within the above range as an absolute value when the emulsion is allowed to stand at 40° C. for 2 weeks or longer, preferably for 1 month.
As a relative value, the value of the average emulsion particle size after standing at 40° C. for 2 weeks or more, preferably 1 month, is preferably 2 times or less of the value of the average emulsion particle size immediately after preparation. More preferably, it is 1.2 times or less.

In addition to the above components, the Pickering emulsion of the present invention may contain optional components that are commonly used in cosmetics as long as they do not impair the effects of the invention. Such optional components include, for example, fatty acid soaps (sodium laurate, sodium palmitate, etc.), potassium lauryl sulfate, anionic surfactants such as alkyl sulfate triethanolamine ether, stearyltrimethylammonium chloride, benzalkonium chloride, lauryl Cationic surfactants such as amine oxides, imidazoline amphoteric surfactants (2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, etc.), betaine surfactants (alkylbetaine, amide betaine, sulfobetaine, etc.), amphoteric surfactants such as acylmethyl taurine, sorbitan fatty acid esters (sorbitan monostearate, sorbitan sesquioleate, etc.), glycerin fatty acids (glyceryl monostearate, etc.), propylene glycol fatty acid esters (propylene glycol monostearate, etc.), hydrogenated castor oil derivatives, glycerin alkyl ether, POE sorbitan fatty acid esters (POE sorbitan monooleate, polyoxyethylene sorbitan monostearate, etc.), POE sorbit fatty acid esters (POE-sorbit monolaurate, etc.), POE glycerin fatty acid esters (POE-glycerin monoisostearate, etc.), POE fatty acid esters (polyethylene glycol monooleate, POE distearate, etc.), POE alkyl ethers (POE 2-octyldodecyl ether, etc.), POE alkylphenyl ethers (POE nonylphenyl ether, etc.), pluronic types, POE/POP alkyl ethers (POE/POP 2-decyltetradecyl ether, etc.), tetronics, POE castor oil/hydrogenated castor oil derivatives (POE castor oil oil, POE hydrogenated castor oil, etc.), nonionic surfactants such as sucrose fatty acid esters and alkyl glucosides, moisturizing ingredients such as sodium pyrrolidonecarboxylate, lactic acid and sodium lactate, optionally surface-treated mica, Powders such as talc, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, silicic anhydride (silica), aluminum oxide, barium sulfate, inorganics such as cobalt oxide, ultramarine blue, Prussian blue, and zinc oxide that may be surface-treated Pigments, optionally surface-treated composite pigments such as iron oxide titanium dioxide sintered bodies, optionally surface-treated titanium mica, fish phosphorus foil, pearl agents such as bismuth oxychloride, laser Red No. 202, Red No. 228, Red No. 226, Yellow No. 4, Blue No. 404, Yellow No. 5, Red No. 505, Red No. 230, Red No. 223, Orange No. 201, Red No. 213 , Yellow No. 204, Yellow No. 203, Blue No. 1, Green No. 201, Purple No. 201, Red No. 204, etc. Organic powders such as polyethylene powder, polymethyl methacrylate, nylon powder, organopolysiloxane elastomer lower alcohols such as ethanol and isopropanol, vitamin A or its derivatives, vitamin B6 hydrochloride, vitamin B6 tripalmitate, vitamin B6 dioctanoate, vitamin B2 or its derivatives, vitamin B such as vitamin B12, vitamin B15 or its derivatives and vitamins such as α-tocopherol, β-tocopherol, γ-tocopherol, vitamin E such as vitamin E acetate, vitamin D, vitamin H, pantothenic acid, pantethine and pyrroloquinoline quinone.

The Pickering emulsion of the present invention may contain a surfactant, but it is preferred that the content be as small as possible. The surfactant content is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0% by mass.

The Pickering emulsion of the present invention can be produced by dispersing powder in an aqueous phase at room temperature and adding an oil phase thereto for emulsification.

The Pickering emulsion of the present invention is suitable for external skin preparations. In particular, it is preferable to make use of the function of the ultraviolet absorber to use it as a sunscreen for external use on the skin.
Among them, it is preferable to use it for cosmetics, and it is preferable to use it as a make-up base, a foundation, and the like.

Pickering emulsions of Examples and Comparative Examples were produced by dispersing silylated silica in a mixture of water phase components among the components shown in Table 1, and adding an oil agent thereto while stirring to emulsify.
The silylated silica used in Test Example 1 was obtained by mixing silica fine particles (manufactured by AEROSIL, average primary particle size 12 nm (measurement method described above)) and mono-, di-, and trimethylsilyl hydrophobizing agents. We used what we got.

(Emulsion stability)
The Pickering emulsions of Examples and Comparative Examples were left at 40° C. for one month. The average emulsion particle size was measured before and after the standing, the increase rate of the average emulsion particle size over time was calculated, and the emulsion stability was evaluated according to the following criteria. Table 1 shows the results.
○・・・100%～120%
△ ... 120% to 200%
×・・・200%～

(Average emulsion particle size)
The Pickering emulsions of Examples and Comparative Examples were observed with an optical microscope, and the average emulsion particle size was measured by the method described above. Table 1 shows the results. Microscopic images of the Pickering emulsions of Example 1 and Comparative Example 1 are shown in FIG.

(Ultraviolet cut power)
The Pickering emulsions of Examples and Comparative Examples were applied to a surgical tape (Transpore, manufactured by 3M Healthcare Co., Ltd.) in an area of 6.4 cm × 6.4 cm with a loading of 2 mg / cm ² , and UV- The SPF value was determined from the average protection spectrum obtained from 10 measurements using a 2000S SPF Analyzer. The evaluation results are shown in Table 1, with ⊚ for SPF of 50 or more, ◯ for SPF of 30 to less than 50, Δ for SPF of 15 to less than 30, and X for less than SPF of 15.

As shown in Table 1 and FIG. 1, the Pickering emulsion of Example 1 containing an acrylates copolymer has a significantly smaller average emulsion particle size than the Pickering emulsion of Comparative Example 1 which does not contain this, and is emulsion stable. was excellent in character.

Further, from the results of Examples 1 to 3 shown in Table 1, it can be seen that the average emulsion particle size is reduced and the emulsion stability is improved depending on the content of the acrylates copolymer.

These results indicate that the addition of an acrylic polymer to a Pickering emulsion can significantly improve the emulsion stability.
This effect is considered to be due to the fact that the acrylic polymer improves the dispersibility of the powder adsorbed on the emulsified interface.

Further, as shown in Table 1, although Examples 4 to 6 differ from Example 1 in the composition of the oil phase, they all have very excellent emulsion stability.
In the prior art, the kind and composition of the oil phase that can provide a stable Pickering emulsion were limited (comparative example 1 if necessary). However, the results shown in Table 1 show that the application of the present invention can greatly improve the degree of freedom.

In addition, the Pickering emulsions of Examples 1 to 3 show excellent emulsification stability, although the UV absorber accounts for about half of the oil phase.
With the prior art, it was difficult to prepare a Pickering emulsion containing a large amount of ultraviolet absorber (comparative example 1 if necessary). However, the results shown in Table 1 indicate that the addition of an acrylic polymer can remarkably improve the emulsification stability of a Pickering emulsion containing a large amount of an ultraviolet absorber.

The present invention is suitable for sunscreen skin preparations for external use.

Claims (14)

The powder is adsorbed on the emulsion interface and contains an acrylic polymer,
A Pickering emulsion characterized in that the ratio of the mass of said powder to the mass of said acrylic polymer is 1.5-8 . The Pickering emulsion according to claim 1, wherein the acrylic polymer comprises a structure derived from (meth)acrylic acid and/or (meth)acrylic acid alkyl ester. 3. The Pickering emulsion according to claim 2, wherein the alkyl group in the (meth)acrylic acid alkyl ester has 1 to 20 carbon atoms. 4. The Pickering emulsion according to claim 2 or 3, wherein the ester residue in the (meth)acrylic acid alkyl ester does not have a substituent. The Pickering emulsion according to claim 2, wherein the alkyl group in the (meth)acrylic acid alkyl ester has 1 to 20 carbon atoms and the ester residue has no substituent. The Pickering emulsion according to any one of claims 1 to 5 , wherein the acrylic polymer is a copolymer containing a structural unit derived from an alkyl (meth)acrylate. Pickering emulsion according to any one of claims 1 to 6 , characterized in that said acrylic polymer is an acrylates copolymer. Pickering emulsion according to any one of claims 1 to 7 , characterized in that it contains a polar oil as an oil phase component. 9. The Pickering emulsion according to claim 8 , wherein the polar oil contains a highly polar oil having an IOB value of 0.1 or more. 10. The Pickering emulsion according to claim 8 or 9 , wherein the proportion of the polar oil in the oil phase contained in the Pickering emulsion is 60% by mass or more. Pickering emulsion according to any one of claims 8 to 10 , characterized in that it contains an ultraviolet absorber as the polar oil. 12. The Pickering emulsion according to claim 11 , wherein the ratio of the ultraviolet absorber to the oil phase contained in the Pickering emulsion is 30% by mass or more. Pickering emulsion according to any one of claims 1 to 12 , characterized in that the average emulsion particle size is 4 µm or less. The Pickering emulsion according to any one of claims 1 to 13 , characterized in that the content of the surfactant other than the powder is 0.1% by mass or less.

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