JP7150411B2 - Oil-in-water emulsified cosmetic - Google Patents

Description

TECHNICAL FIELD The present invention relates to an oil-in-water emulsified cosmetic, particularly a sunscreen cosmetic, which contains an ultraviolet absorber and an ultraviolet scattering agent, has a high ultraviolet protection function (SPF), and has a unique fresh feeling in use.

Oil-in-water emulsified cosmetics are widely used as bases that provide a refreshing feeling in use compared to water-in-oil emulsions. However, when a powder, especially a hydrophobized powder, is added to the internal phase (oil phase), the emulsification system tends to become unstable.

Attempts have been made to thicken the external phase (aqueous phase) of an oil-in-water emulsifying base with a water-soluble thickener as one method of stabilizing an emulsified system. However, it has been regarded as a problem that the viscosity of the water phase is lowered due to the elution of ions from the hydrophobized powder blended in the internal phase (oil phase), resulting in instability and stickiness (Patent Document 1). Patent Literature 1 discloses that elution is prevented by firmly coating the surface of inorganic powder.

As another stabilization method, a method of using a low-viscosity oil (dispersion medium) or a dispersant to promote dispersion of the powder has been proposed. For example, in Patent Document 2, a UV scattering agent (zinc oxide) hydrophobized by using a volatile oil, a liquid higher fatty acid (dispersion medium), and a silicone or sugar ester (dispersant) having a carboxyl group in its structure. It is said to be stably blended in the oil phase.

However, it is common to use a (volatile) non-polar oil such as a low-viscosity hydrocarbon oil or silicone oil as a dispersion medium blended for powder dispersion. It has been known that emulsification becomes difficult due to increased distribution of the hydrophilic groups of the agent into the oil phase.
That is, in order to achieve high UV protection performance, it is necessary to blend a highly polar UV absorber and, in some cases, a polar oil as a solvent thereof. Since it is necessary to add a non-polar oil as a dispersion medium, it was extremely difficult to control the total amount of oil while maintaining high UV protection.

For example, Patent Document 3 describes 2-ethylhexyl 2-ethylhexanoate and/or isononyl 2-ethylhexanoate in a system in which a highly polar ultraviolet absorber, a nonpolar silicone oil, and an ultraviolet scattering agent (powder) coexist. is used as an emulsifier to obtain a stable emulsion. Further, Patent Document 4 describes an oil-in-water emulsified cosmetic in which a hydrophobized alkylcellulose is used as an emulsifier and a hydrophobized powder is stably blended in the oil phase. However, in these cosmetics, more than half of the oil phase (internal phase) is occupied by non-polar oil, so there is a limit to the suppression of the total amount of oil.

JP 2012-251152 A JP 2012-111726 A JP 2007-145722 A JP 2013-199453 A

As described above, in conventional oil-in-water emulsified sunscreen cosmetics, it is necessary to increase the oil content in order to achieve a high SPF by stably blending an ultraviolet absorber and an ultraviolet scattering agent. There is a problem that the fresh feeling peculiar to the type emulsion is lost, and conversely, if the oil content is suppressed with emphasis on the feeling during use, the UV protection ability obtained is limited.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an oil-in-water emulsified cosmetic which, when applied to the skin, has a unique fresh feeling of use that melts away and is excellent in UV protection.

In order to solve the above problems, the present inventors conducted extensive research and found that a hydrophobically modified cellulose derivative with a specific structure is used as an emulsifier, and an ultraviolet absorber and a hydrophobically treated ultraviolet scattering agent are added to the oil phase (internal phase). The present inventors have found that a high SPF can be achieved while maintaining a unique fresh texture by blending a thickener with low salt resistance in the aqueous phase (external phase), and have completed the present invention.

That is, the present invention
(A) 0.05-1% by weight of hydrophobically modified alkyl cellulose;
(B) 5 to 40% by mass of oil;
(C) 2.5 to 30% by weight of a UV scattering agent having a hydrophobic surface; and (D) an aqueous phase thickener with low salt tolerance,
Provided is an oil-in-water emulsified cosmetic, characterized in that the (C) UV scattering agent is dispersed in an oil phase.

The oil-in-water emulsified cosmetic composition of the present invention uses a hydrophobically modified alkylcellulose as an emulsifier and contains a thickener in the aqueous phase, thereby suppressing the total amount of oil and containing a large amount of an ultraviolet absorber and an ultraviolet scattering agent. A high SPF can be achieved. Furthermore, in the present invention, by blending a thickener with low salt tolerance in the water phase, which was previously avoided because it adversely affects emulsion stability, a unique fresh feeling that melts when applied to the skin is achieved. You can get an excellent feeling of use that gives you.
As used herein, the term “unique fresh feel” means that when the cosmetic is applied to the skin with fingers or the like, there is a feeling of a sudden decrease in viscosity and the feeling of crumbling, and at the same time, a very fresh feel that spreads across the skin. means to give

The present invention will be described in detail below.
The oil-in-water emulsified cosmetic of the present invention (hereinafter also simply referred to as "emulsified cosmetic") includes (A) hydrophobically modified alkyl cellulose; (B) oil; (C) an ultraviolet scattering agent having a hydrophobic surface; D) Contains an aqueous phase thickener with low salt tolerance as an essential ingredient.

［式中、Ｒは、同一でも異なってもよく、水素原子、炭素原子数が１～４のアルキル基、基－［ＣＨ_２ＣＨ（ＣＨ_３）Ｏ］_ｍ－Ｈ（式中、ｍは、１～５、好適には１～３の整数である）、基－ＣＨ_２ＣＨ_２ＯＨ、及び、基－ＣＨ_２ＣＨ（ＯＨ）ＣＨ_２ＯＲ’（式中、Ｒ’は、炭素原子数が１４～２２のアルキル基である）から選ばれる１種以上の基であるが、基－ＣＨ_２ＣＨ（ＯＨ）ＣＨ_２ＯＲ’を必ず含むものとする。また、Ａは、基－（ＣＨ_２）_ｑ－（ｑは、１～３の整数であり、好適には１である）であり、ｎは、１００～１００００、好適には５００～５０００の整数である。］ The (A) hydrophobically modified alkyl cellulose used in the present invention means an alkyl cellulose hydrophobically modified with an alkyl group having 14 to 22 carbon atoms. This hydrophobically modified alkylcellulose is a compound obtained by introducing a long-chain alkyl group, which is a hydrophobic group, into a water-soluble cellulose ether derivative, and is represented by the following general formula (I).

[In the formula, R may be the same or different, and is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group -[CH ₂ CH(CH ₃ )O] _m -H (wherein m is an integer of 1 to 5, preferably 1 to 3), the group —CH ₂ CH ₂ OH, and the group —CH ₂ CH(OH)CH ₂ OR′, where R′ is an integer having the number of carbon atoms 14 to 22 alkyl groups), but necessarily including the group —CH ₂ CH(OH)CH ₂ OR′. A is a group —(CH ₂ ) _q — (q is an integer of 1 to 3, preferably 1); n is an integer of 100 to 10,000, preferably 500 to 5,000; is. ]

［Ｒ’は、炭素原子数が１４～２２のアルキル基である。］ The method for producing the hydrophobically modified alkyl cellulose of the formula (I) generally includes a base water-soluble cellulose ether derivative, specifically methyl cellulose (R is a hydrogen atom or a methyl group), ethyl cellulose (R is a hydrogen atom or ethyl group), propyl cellulose (R is a hydrogen atom or a propyl group), butyl cellulose (R is a hydrogen atom or a butyl group), hydroxypropyl cellulose [R is a hydrogen atom or a hydroxypropyl group (the group -[CH ₂ CH (CH ₃ ) O] _m —H (wherein m is an integer of 1 to 5, preferably 1 to 3))], hydroxypropylmethylcellulose (R is a hydrogen atom, a methyl group or a hydroxypropyl group (same as above)), etc. can be obtained by contacting a compound for introducing a long-chain alkyl group having 14 to 22 carbon atoms, specifically, a long-chain alkyl glycidyl ether of the following formula (II) in the presence of an alkali catalyst.

[R′ is an alkyl group having 14 to 22 carbon atoms. ]

The content of the group —CH ₂ CH(OH)CH ₂ OR′ introduced into the hydrophobically-modified alkylcellulose of the present invention is preferably about 0.1 to 5.0% by mass relative to the entire hydrophobically-modified alkylcellulose. . In order to achieve such a content, the molar ratio, reaction time, type of alkali catalyst, etc. in the reaction between the water-soluble cellulose ester derivative and the long-chain alkyl glycidyl ether may be appropriately selected. After the above reaction, purification steps such as neutralization, filtration, washing, drying, and sieving of the reaction product may be performed.

Among the above water-soluble cellulose ether derivatives, it is particularly preferable to select hydroxypropylmethylcellulose (wherein R in formula (I) is a hydrogen atom, a methyl group, or a group -[CH ₂ CH ( CH ₃ )O] _m H and the group —CH ₂ CH(OH)CH ₂ OR′, q of the group A becomes 1, and the A becomes a methylene group).
Furthermore, R' in the long-chain alkyl glycidyl ether of formula (II) is an alkyl group having 14 to 22 carbon atoms, preferably an alkyl group having 14 to 20 carbon atoms, more preferably a stearyl group having 18 carbon atoms (-C _{18 H37} ). If the number of carbon atoms in the alkyl group R' is less than 14 or 23 or more, the emulsion stability of the obtained hydrophobically modified alkyl cellulose is not sufficient.

The weight average molecular weight of the hydrophobically modified alkylcellulose is preferably 100,000 to 1,000,000, more preferably 300,000 to 800,000, still more preferably 550,000 to 750,000.
In the present invention, it is most preferable to use stearoxyhydroxypropylcellulose as the hydrophobically modified alkylcellulose, and commercially available products can also be used. Examples thereof include Sangelose 90L (display name: hydrophobized hydroxypropyl methylcellulose; manufactured by Daido Kasei Co., Ltd.), Natrosol Plus 330cs (manufactured by Ashland), Polysurf 67cs (manufactured by Ashland) and the like.

The amount of hydrophobically modified alkyl cellulose (A) blended in the emulsified cosmetic composition of the present invention is 0.05 to 1% by mass, preferably 0.1 to 0.5% by mass, more preferably 0.1 to 0.3% by mass. %. If it is less than 0.05% by mass, sufficient emulsion stability cannot be obtained, and even if it exceeds 1% by mass, it is difficult to obtain a further increase in the effect.

The (B) oil component in the emulsified cosmetic composition of the present invention can be one or more selected from oily components commonly used in cosmetics and the like.
The blending amount of the (B) oil component is 5 to 40% by mass, preferably 10 to 40% by mass, more preferably 20 to 35% by mass relative to the emulsified cosmetic.

In the emulsified cosmetic composition of the present invention, polar oil accounts for 55% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more of the oil (B). Emulsion stability can be further improved. The upper limit of the ratio of the polar oil to the oil content is not particularly limited. For example, the polar oil may account for 90% or more, or 100% of the oil may be the polar oil.

The "polar oil" used herein is not particularly limited as long as it has a high polarity among the oils generally used in cosmetics. For example, an oil having a dielectric constant of about 5 or more, preferably about 10 or more is preferably used.
Representative examples of polar oils in the emulsified cosmetic composition of the present invention include ester oils and UV absorbers. In addition, since it contains a larger amount of polar oil than conventional emulsified cosmetics, it is possible to stably incorporate, for example, a highly polar perfume.

Specific examples of ester oils suitable for emulsified cosmetics of the present invention include tripropylene glycol dineopentanoate, isononyl isononanoate, isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, and lauric acid. Hexyl, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearate, cetyl ethylhexanoate, di-2-ethyl Ethylene glycol hexanoate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glyceryl di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate , trimethylolpropane triisostearate, pentaerythrityl tetra-2-ethylhexanoate, triethylhexanoin (glyceryl tri-2-ethylhexanoate), glyceryl trioctanoate, glyceryl triisopalmitate, trimethylolpropane triisostearate, Cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glyceryl trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl ester, oleyl oleate, acetoglyceride, 2-heptylundecyl palmitate, adipine diisobutyl acid, N-lauroyl-L-glutamic acid-2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-palmitate Hexyldecyl, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, triethyl citrate and the like are included.

As the UV absorber, a wide range of highly polar oily UV absorbers generally used in cosmetics can be mentioned, and there is no particular limitation. For example, benzoic acid derivatives, salicylic acid derivatives, cinnamic acid derivatives, dibenzoylmethane derivatives, β,β-diphenylacrylate derivatives, benzophenone derivatives, benzylidene camphor derivatives, phenylbenzimidazole derivatives, triazine derivatives, phenylbenzotriazole derivatives, anthranyl derivatives. , imidazoline derivatives, benzalmalonate derivatives, 4,4-diarylbutadiene derivatives and the like. Specific examples and product names are listed below, but are not limited to these.

Examples of benzoic acid derivatives include ethyl para-aminobenzoate (PABA), ethyl-dihydroxypropyl PABA, ethylhexyl-dimethyl PABA (eg "Escarol 507"; ISP), glyceryl PABA, PEG-25-PABA (eg "Ubinal P25"; BASF), diethylaminohydroxybenzoyl hexyl benzoate (eg, "Ubinal A Plus"), and the like.

Salicylic acid derivatives include homosalate ("Eusolex HMS"; Rona/EM Industries), ethylhexyl salicylate (e.g. "NeoHeliopan OS"; Harman & Reimer), dipropylene glycol. Examples include salicylates (eg "Dipsal"; Skell), TEA salicylates (eg "Neo Heliopan TS"; Harman & Reimer) and the like.

Cinnamic acid derivatives include octyl methoxycinnamate or ethylhexyl methoxycinnamate (eg "Parsol MCX"; Hoffman-La Roche), isopropyl methoxycinnamate, isoamyl methoxycinnamate (eg "Neo Heliopan E1000 Harman & Reimer Co.), cinnoxate, DEA methoxycinnamate, diisopropyl methylcinnamate, glyceryl-ethylhexanoate-dimethoxycinnamate, di-(2-ethylhexyl)-4'-methoxybenzalmalonate, etc. are exemplified.
Examples of dibenzoylmethane derivatives include 4-tert-butyl-4′-methoxydibenzoylmethane (eg “Parsol 1789”).

Examples of β,β-diphenyl acrylate derivatives include octocrylene (eg, “Ubinal N539”; BASF).
Benzophenone derivatives include benzophenone-1 (eg "Ubinal 400"; BASF), benzophenone-2 (eg "Ubinal D50"; BASF), benzophenone-3 or oxybenzone (eg "Ubinal M40"; BASF), benzophenone. -4 (eg "Ubinal MS40"; BASF), benzophenone-5, benzophenone-6 (eg "Helisorb 11"; Norkai), benzophenone-8 (eg "Spectra-Sorb UV- 24”; American Cyanamid), benzophenone-9 (for example, “Uvinal DS-49”; BASF), benzophenone-12, and the like.

Examples of benzylidene camphor derivatives include 3-benzylidene camphor (eg "Mexoryl SD"; Simex), 4-methylbenzylidene camphor, benzylidene camphor sulfonic acid (eg "Megizolyl SL"; Simex), methosulfate camphor benzalco (e.g., "Megizolyl SO"; Simex), terephthalylidene dicamphorsulfonic acid (eg, "Megizolyl SX"; Simex), polyacrylamidemethylbenzylidene camphor (eg, "Megizolyl SW"; Simex), and the like. .
Phenylbenzimidazole derivatives include phenylbenzimidazole sulfonic acid (e.g. "Usolex 232"; Merck), disodium phenyldibenzimidazole tetrasulfonate (e.g. "Neo Heliopan AP"; Harman & Reimer), and the like. exemplified.

Triazine derivatives include anisotriazine (e.g. "Tinosorb S"; Ciba Specialty Chemicals), ethylhexyl triazone (e.g. "Uvinal T150"; BASF), diethihexylbutamide triazone (e.g. " Uvasorb HEB"; Sigma 3 V Company), 2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine and the like.
Phenylbenzotriazole derivatives include drometrizole trisiloxane (e.g. "Silatrizole"; Rhodia Shimmy), methylenebis(benzotriazolyltetramethylbutylphenol) (e.g. "Tinosorb M" (Ciba Specialty Co., Ltd.). Chemicals Co.)) and the like are exemplified.
Examples of anthranil derivatives include menthyl anthranilate (for example, "Neo Heliopan MA"; Harman & Reimer).
Examples of imidazoline derivatives include ethylhexyl dimethoxybenzylidene dioxoimidazoline propionate.
Examples of benzalmalonate derivatives include polyorganosiloxanes having benzalmalonate functional groups (eg, polysilicone-15; "Parsol SLX"; DSM Nutrition Japan).
Examples of 4,4-diarylbutadiene derivatives include 1,1-dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene.

Other oils that can be blended with the polar oil (hereinafter also referred to as “non-polar oils”) are low-polar oils among the oils that are generally blended in cosmetics. It can be one or two or more selected from less than oil.

The compounding amount of the ultraviolet absorber contained in the polar oil is, for example, 40% by mass or more, preferably 50% by mass or more, and more preferably 60% by mass or more of the polar oil.
The amount of the ultraviolet absorber to be blended in the emulsified cosmetic is 5 to 25% by mass, preferably 8 to 23% by mass, more preferably 10 to 20% by mass.

The non-polar oil blended in the emulsified cosmetic composition of the present invention is not particularly limited, but is preferably selected from volatile or non-volatile silicone oils and hydrocarbon oils.
Specific examples include linear silicone oils such as polydimethylsiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; and cyclic silicone oils such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane. Hydrocarbon oils such as decane, dodecane, isododecane, isohexadecane, liquid paraffin, squalane, squalene, and paraffin, and the like.

Zinc oxide or titanium oxide powder is preferably used as the base material for (C) the ultraviolet scattering agent having a hydrophobic surface in the emulsified cosmetic composition of the present invention.
The zinc oxide and titanium oxide used in the present invention are not particularly limited and can be appropriately selected from those commonly used in cosmetics.

The ultraviolet scattering agent (C) used in the present invention is an ultraviolet scattering agent having a hydrophobic surface obtained by hydrophobizing the surface of a substrate such as zinc oxide or titanium oxide.
Examples of methods for surface hydrophobizing treatment include silicone treatment with methylhydrogenpolysiloxane, methylpolysiloxane, etc.; fluorine treatment with perfluoroalkyl phosphate, perfluoroalcohol, etc.; amino acid treatment with N-acylglutamic acid, etc.; treatment; metal soap treatment; fatty acid treatment; alkyl phosphate treatment, and the like.

The blending amount of (C) the ultraviolet scattering agent having a hydrophobic surface in the emulsified cosmetic composition of the present invention is 2.5 to 30% by mass, preferably 3 to 30% by mass, more preferably 4 to 20% by mass. If the blending amount is less than 2.5% by mass, it is difficult to obtain a higher SPF value than in the past, and there is a tendency that the unique fresh feel during application cannot be obtained. On the other hand, if the content exceeds 30% by mass, the emulsion stability and usability may deteriorate.

The (D) water-phase thickener with low salt tolerance in the present invention is a thickener having a function of thickening the water phase, and the viscosity is reduced by the presence of an electrolyte having a concentration within the range generally blended in cosmetics. is the one that produces Such a thickener with low salt tolerance is selected from water-soluble thickeners conventionally blended in cosmetics and the like for the purpose of adjusting the viscosity of the aqueous phase.

Specific examples include polyvinyl alcohol, polyvinyl acetate, polyvinyl methyl ether, polyvinylpyrrolidone, copolymers of vinylpyrrolidone and vinyl acetate, vinyl polymers such as carboxyvinyl polymer; sodium polyacrylate, polyethyl acrylate, polyalkanol acrylate. Amine, copolymer of alkyl methacrylate and dimethylaminoethyl methacrylate, poly 2-acrylamido-2-methylpropanesulfonic acid, polymethacryloyloxytrimethylammonium, (acryloyldimethyltaurate ammonium/VP) copolymer, dimethylacrylamide/acryloyldimethyltaurate Na) cross Acrylic macromolecules such as polymers can be mentioned.

However, among thickeners with low salt tolerance (viscosity decreases with an increase in electrolyte concentration), compared to thickeners that thicken due to entanglement of polymer chains, water-swelling microgels in the aqueous phase It is preferable to use a type of thickening agent that forms a . This is because the hydrophobically modified alkyl cellulose blended as an emulsifier also has a thickening effect due to the entanglement of polymer chains, so if a thickener that thickens by the same mechanism is further blended, the thickening effect is promoted. This is because it can cause sliminess.

The amount of the (D) water-phase thickener with low salt tolerance in the emulsified cosmetic composition of the present invention is 0.05 to 3% by mass, preferably 0.1 to 2% by mass, more preferably 0.15 to 1% by mass. % by mass. If it is less than 0.05% by mass, the function as a thickening agent (viscosity adjustment and emulsion stabilization) cannot be exhibited, and the unique fresh feel at the time of application cannot be obtained. If the content exceeds 3% by mass, stickiness and sliminess may occur.

In addition to the essential components (A) to (D), the emulsified cosmetic composition of the present invention can contain various components that are usually blended in cosmetics as long as the effects of the present invention are not impaired. Specific examples include glycols such as propylene glycol, dipropylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol; glycerins such as glycerin, diglycerin, and polyglycerin; sugar alcohols such as sorbitol, mannitol, maltitol, xylitol, erythritol; sugars such as fructose, glucose, galactose, maltose, lactose and trehalose; natural pigments such as chlorophyll and β-carotene; gum arabic, gum tragacanth, galactan, plant polymers such as guar gum, carob gum, karaya gum, gellan gum, carrageenan; microbial polymers such as xanthan gum, dextran, succinoglucan and pullulan; animal polymers such as collagen, casein, albumin and gelatin; Starch-based polymers such as methylhydroxypropyl starch; Cellulose-based polymers such as methylcellulose, ethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, sodium cellulose sulfate, hydroxypropylcellulose, sodium carboxymethylcellulose, and crystalline cellulose; sodium alginate, propylene glycol alginate Alginate-based polymers such as esters; Other thickeners; Vitamins such as magnesium ascorbyl phosphate, ascorbyl glucoside, vitamin B6 hydrochloride, pantothenyl ethyl ether; Bactericides, antiphlogistic agents, preservatives, plant extracts , amino acids, chemicals such as cooling agents; lower alcohols such as ethanol and isopropyl alcohol; aromatic alcohols such as phenoxyethanol and benzyl alcohol;

The emulsified cosmetic of the present invention is an oil-in-water emulsified composition by using a hydrophobically modified alkyl cellulose as an emulsifier, and has a polar oil containing an ultraviolet absorber in the internal phase (oil phase) and a hydrophobic surface for ultraviolet scattering. The agent can be blended in a higher amount than conventional oil-in-water cosmetics, and exhibits excellent UV protection. Furthermore, by increasing the proportion of polar oil, which was conventionally considered to be one of the causes of destabilization, to 55% by mass or more of the oil phase, a surprising effect of improving emulsification stability is obtained.
On the other hand, since the hydrophobically modified alkyl cellulose has a moderate emulsifying power, the UV scattering agent contained in the internal phase (oil phase) easily interacts with the external phase (aqueous phase). It is thought that the electrolyte (ultraviolet light scattering agent, etc.) coming out of the water comes into contact with the thickener in the water phase and rapidly lowers the viscosity, resulting in a unique melt-in-your-mouth feeling of freshness. Therefore, the emulsified cosmetic of the present invention preferably does not substantially contain emulsifiers other than hydrophobically modified alkyl cellulose, particularly emulsifiers having strong emulsifying power. When other emulsifiers are blended, the blending amount is preferably about 3% by mass or less, or about 1% by mass or less.

The emulsified cosmetic of the present invention can be prepared according to a method commonly used for oil-in-water emulsified cosmetics. That is, it can be prepared by separately mixing the water phase component and the oil phase component, adding the oil phase component while stirring the water phase component, and emulsifying the water phase component.

The emulsified cosmetic composition of the present invention is not particularly limited, but usually preferably has an internal phase (oil phase) with an average particle size of about 15 μm or less.

Hereinafter, the present invention will be described in more detail with specific examples, but these do not limit the technical scope of the present invention.
In addition, unless otherwise specified, the blending amounts in the following examples and the like are mass %.

Oil-in-water emulsified cosmetics were prepared according to the formulations shown in Tables 1 to 5 below, and their properties were evaluated according to the following evaluation methods and evaluation criteria. These results are also shown in the table.

1. Evaluation Method of Feeling in Use Each sample of Examples and Comparative Examples was actually used by a panel of five experts, and the feeling in use was evaluated. Each panel was asked to evaluate in 5 grades according to the following evaluation criteria, and the total score was used for judgment based on the following evaluation criteria.
"Evaluation item"
(1) Unique fresh feeling in use As defined above, when applied to the skin, it should provide a feeling of falling apart due to a sudden decrease in viscosity and a feeling of spreading freshness on the skin.
(2) Feeling of sliminess when blended The cosmetic should not feel slimy when blended with the skin.
"Evaluation point criteria"
5: Very good 4: Excellent 3: Normal 2: Poor 1: Very poor "Evaluation criteria"
A: Total score is 20 points or more B: Total score is 15-19 points C: Total score is 14 points or less

2. Emulsion Stability A sample was filled in two screw tubes (50 ml) and allowed to stand in a constant temperature bath at 0° C. or 50° C. for 2 weeks. Before and after standing, the change in viscosity was measured using a rotary viscometer (vismetron rotary viscometer), and the emulsified particles and appearance were observed.
"Evaluation criteria"
A: No decrease in viscosity was observed at either temperature level of 0°C or 50°C, and there was no problem with the emulsified particles and appearance.
B: A slight decrease in viscosity, an increase in emulsified particles, and a change in appearance were observed at any temperature level.
C: At any temperature level, a slight decrease in viscosity, an increase in emulsified particles, and a change in appearance were observed.
D: Significant reduction in viscosity, increase in emulsified particles, and change in appearance were observed at any temperature level.
E: A significant decrease in viscosity, an increase in emulsified particles, or a change in appearance was observed at any temperature level.

Based on the results shown in Table 1, the oil phase was blended with a highly polar UV absorber and a hydrophobic surface-treated UV scattering agent using hydrophobically modified alkyl cellulose as an emulsifier, and the water phase was thickened with a low salt-tolerant thickener. The viscous oil-in-water emulsified cosmetics (Examples 1 to 5) gave a unique fresh feeling when applied. It was insufficient to reduce the viscosity, and the desired feel during use was not obtained. Even in an emulsified cosmetic prepared by thickening an aqueous phase with a highly salt-tolerant thickener, a unique fresh feeling in use cannot be obtained.

The unique fresh texture obtained in Table 1 (Examples 1 to 5) was exhibited even when the type of thickener with low salt tolerance blended in the water phase was changed (Examples 6 and 7). However, in Example 8 using a thickening agent (carbomer) that thickens by molecular entanglement, a slight sliminess was felt when the cosmetic was applied to the skin.

Examples 9 to 11, in which the polar oil blended in Example 6 was replaced with another polar oil, also gave a unique feel in use, as in Example 6, and were also excellent in emulsion stability.

In Examples 1 to 11 shown in Tables 1 to 3, the proportion of polar oil in the total oil content exceeded 55%, indicating extremely excellent emulsion stability, but the proportion of polar oil in the total oil content was In Examples 12 to 14 with less than 55%, the emulsification stability was slightly lowered (however, there was no practical problem). In Example 15, in which EDTA-3Na, which is a chelating agent, was added to Example 12, the emulsion stability was improved by the addition of the chelating agent, but there was a tendency that the unique fresh feeling in use tended to decrease somewhat. . This is probably because part of the electrolyte was captured by the chelating agent and the rapid decrease in viscosity was somewhat inhibited. Therefore, it is presumed that the amount of chelating agent blended in the emulsified cosmetic of the present invention should preferably be kept to a minimum.

From the results shown in Table 5, Examples 16 to 19 in which hydrophobically modified alkyl cellulose was used as an emulsifier, the water phase was thickened with a thickener having low salt resistance, and the polar oil ratio in the oil phase was 55% by mass or more. It was further confirmed that, regardless of the base material of the UV scattering agent with a hydrophobic surface and the type of surface treatment agent that is blended in the oil phase, a unique fresh feeling during use is obtained, and the emulsification stability is also extremely excellent. was done.

(Example 20)
An oil-in-water emulsified sunscreen cosmetic was prepared with the composition shown below. The cosmetic thus obtained gave a unique melting and fresh feel when applied to the skin, and had an SPF of about 55 after application.
Ingredients Amount (% by mass)
(1) Water 48.95
(2) Ethanol 10.00
(3) zinc oxide 9.30
(4) Butylene glycol 8.00
(5) Glycerin 2.00
(6) Polybutylene glycol/PPG-9/1 copolymer 2.00
(7) stearoxyhydroxypropyl methylcellulose 0.20
(8) Ethylhexyl methoxycinnamate 10.00
(9) Polysilicone-15 2.00
(10) Hexyl diethylaminohydroxybenzoylbenzoate 2.00
(11) Bisethylhexyloxyphenol methoxyphenyltriazine
1.50
(12) Cetyl ethylhexanoate 3.00
(13) Triethoxycaprylylsilane 0.70
(14) (dimethylacrylamide/acryloyldimethyltaurate Na) crosspolymer
0.30
(15) Perfume 0.05

The present invention includes the following aspects (1): (A) 0.05 to 1% by mass of hydrophobically modified alkyl cellulose;
(B) 5 to 40% by mass of oil;
(C) 2.5 to 30% by weight of a UV scattering agent having a hydrophobic surface; and (D) an aqueous phase thickener with low salt tolerance,
An oil-in-water emulsified cosmetic, wherein the ultraviolet scattering agent (C) is dispersed in an oil phase.
(2): The cosmetic according to (1), wherein (A) the hydrophobically modified alkylcellulose is hydrophobized hydroxypropylmethylcellulose.
(3): The above-mentioned (D) water-phase thickener with low salt tolerance forms a water-swellable microgel in the water phase, and is a type of thickener that thickens due to friction between the swollen microgel particles. The cosmetic according to (1) or (2).
(4): The cosmetic according to (1) or (2), wherein the (D) water-phase thickener having low salt tolerance comprises a vinyl-based polymer or an acrylic-based polymer.
(5): The cosmetic according to any one of (1) to (4), wherein polar oil accounts for 55% by mass or more of the oil (B).
(6): The cosmetic according to any one of (1) to (5), which is a sunscreen cosmetic.

Claims (5)

(A) 0.05-1% by weight of hydrophobically modified alkyl cellulose;
(B) 5 to 40% by mass of oil;
(C) 2.5 to 30% by mass of a UV scattering agent having a hydrophobic surface;
The (A) hydrophobically modified alkyl cellulose has the following general formula (I)

[In the formula, R may be the same or different, and is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group -[CH ₂ CH(CH ₃ )O] _m -H (wherein m is an integer of 1 to 5), the group —CH ₂ CH ₂ OH, and the group —CH ₂ CH(OH)CH ₂ OR′ (where R′ is an alkyl group having 14 to 22 carbon atoms) to One or more selected groups, which must include the group —CH ₂ CH(OH)CH ₂ OR′, where A is the group —(CH ₂ ) _q —, where q is an integer from 1 to 3 ) and n is an integer from 100 to 10000],
The (B) oil contains a polar oil containing an ultraviolet absorber,
The (C) ultraviolet scattering agent is dispersed in the oil phase,
The (D) aqueous phase thickener is sodium polyacrylate, alkanolamine polyacrylate, copolymer of alkyl methacrylate and dimethylaminoethyl methacrylate, poly 2-acrylamido-2-methylpropanesulfonic acid, polymethacryloyloxytrimethylammonium. , (dimethylacrylamide/acryloyldimethyltaurate Na) crosspolymer, and at least one selected from the group consisting of
An oil-in-water emulsified cosmetic, wherein the amount of the emulsifier other than (A) is 1% by mass or less. 2. The cosmetic material according to claim 1, wherein (A) the hydrophobically modified alkylcellulose is hydrophobized hydroxypropylmethylcellulose. 3. According to claim 1 or 2, the water-phase thickener (D) is a type of thickener that forms a water-swellable microgel in the water phase and thickens due to friction between swollen microgel particles. Cosmetics as described. The cosmetic according to any one of claims 1 to 3, wherein the (D) aqueous phase thickener comprises a (dimethylacrylamide/acryloyldimethyltaurate Na) crosspolymer. The cosmetic according to any one of claims 1 to 4, which is a sunscreen cosmetic.