JP2017061548A - Oil-in-water emulsion cosmetic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-in-water emulsion cosmetic which achieves a high SPF by highly blending an ultraviolet absorbing agent and an ultraviolet scattering agent into an oil phase while providing a unique fresh use feeling when applied to skin.SOLUTION: An oil-in-water emulsion cosmetic comprises: (A) 0.05-1 mass% of hydrophobically modified alkyl cellulose; (B) 5-40 mass% of oil content; (C) 2.5-30 mass% of an ultraviolet scattering agent having a hydrophobic surface; and (D) a water phase thickener with low salt tolerance; where the (C) ultraviolet scattering agent is dispersed in the oil phase.SELECTED DRAWING: None

Description

  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 and has a unique and fresh feeling of use while having high ultraviolet protective ability (SPF).

  Oil-in-water emulsified cosmetics are widely used as a base that gives a refreshing feel to use as compared to a water-in-oil type. However, when a powder, particularly a hydrophobized powder, is blended with the internal phase (oil phase), the emulsification system tends to become unstable.

  As one method for stabilizing the emulsification system, attempts have been made to thicken the outer phase (aqueous phase) of the oil-in-water emulsion base with a water-soluble thickener. However, it has been regarded as a problem that the viscosity of the aqueous phase decreases due to ion elution from the hydrophobized powder blended in the inner phase (oil phase), resulting in instability and stickiness (Patent Document 1). Patent Document 1 discloses that elution is prevented by firmly covering the surface of an inorganic powder.

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

However, it is common to use (volatile) nonpolar oils such as low-viscosity hydrocarbon oils and silicone oils as the dispersion medium to be mixed for powder dispersion. It has been known that the amount of the hydrophilic group of the agent distributed to the oil phase increases and emulsification becomes difficult.
That is, in order to achieve high UV protection ability, it is necessary to blend a high-polarity UV absorber and, in some cases, a polar oil as a solvent thereof, while stably emulsifying the oil phase containing the UV scattering agent. Therefore, it is extremely difficult to suppress the total amount of oil while maintaining high UV protection ability.

  For example, Patent Document 3 discloses that 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. It is described that a stable emulsion was obtained by using as an emulsifier. Patent Document 4 describes an oil-in-water emulsified cosmetic in which hydrophobically modified alkyl cellulose is used as an emulsifier and a hydrophobized powder is stably blended in an oil phase. However, in these cosmetics, since non-polar oil accounts for more than half of the oil phase (inner phase), there is a limit to the suppression of the total oil content.

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

As described above, in the conventional oil-in-water type emulsion sunscreen cosmetics, it is necessary to increase the amount of oil 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 of use peculiar to the type emulsion is lost, and conversely, when the oil content is suppressed with emphasis on the feeling of use, the obtained ultraviolet protection ability is limited.
Accordingly, an object of the present invention is to provide an oil-in-water emulsified cosmetic that has a unique and fresh feeling of use that melts away when applied to the skin, and that is also excellent in UV protection.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive research. As a result, a hydrophobically modified cellulose derivative having a specific structure was used as an emulsifier, and an ultraviolet absorber and a hydrophobically treated ultraviolet scattering agent were applied to the oil phase (inner phase). In addition, the present inventors have found that a high SPF can be achieved while maintaining a unique and fresh feeling of use by blending a thickener with low salt resistance into the aqueous phase (external phase).

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

The oil-in-water emulsified cosmetic composition of the present invention is a highly blended UV absorber and UV scattering agent while suppressing the total amount of oil by using a hydrophobically modified alkyl cellulose as an emulsifier and adding a thickener in the aqueous phase. High SPF can be achieved. Furthermore, in the present invention, a unique and fresh feel that melts when applied to the skin by adding a thickening agent having low salt resistance, which has been avoided in the past because it adversely affects emulsion stability, to the aqueous phase. An excellent usability is obtained.
In this specification, “unique and fresh touch” means that when cosmetics are applied to the skin with fingers or the like, there is a touch that rapidly decreases in viscosity and collapses, and at the same time, a very fresh touch that spreads against the skin. Means giving.

Hereinafter, the present invention will be described in detail.
The oil-in-water emulsified cosmetic of the present invention (hereinafter also simply referred to as “emulsified cosmetic”) includes (A) a hydrophobically modified alkyl cellulose; (B) an oil component; (C) an ultraviolet scattering agent having a hydrophobic surface; D) An aqueous phase thickener with low salt resistance is contained as an essential component.

The (A) hydrophobically modified alkylcellulose used in the present invention means an alkylcellulose that is hydrophobically modified with an alkyl group having 14 to 22 carbon atoms. This hydrophobically modified alkyl cellulose is a compound in which a long-chain alkyl group that is a hydrophobic group is introduced into a water-soluble cellulose ether derivative, and is represented by the following general formula (I).
[Wherein R may be the same or different, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a group — [CH ₂ CH (CH ₃ ) O] _m —H (wherein m is 1 to 5, preferably an integer of 1 to 3, a group —CH ₂ CH ₂ OH, and a group —CH ₂ CH (OH) CH ₂ OR ′ where R ′ is the number of carbon atoms. It is one or more groups selected from 14 to 22 alkyl groups), but must include 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), and n is an integer of 100 to 10000, preferably 500 to 5000. It is. ]

The method for producing the hydrophobically modified alkyl cellulose of the formula (I) is generally based on a water-soluble cellulose ether derivative as a base, specifically, methyl cellulose (R is a hydrogen atom or a methyl group), ethyl cellulose (R is a hydrogen atom or ethyl). Group), propylcellulose (R is a hydrogen atom or propyl group), butylcellulose (R is a hydrogen atom or butyl group), hydroxypropylcellulose [R is a hydrogen atom or a hydroxypropyl group (group- [CH ₂ CH (CH ₃ ) O] _m -H (wherein m is an integer of 1 to 5, preferably 1 to 3))], hydroxypropyl methylcellulose (R is a hydrogen atom, a methyl group or a hydroxypropyl group (same as above)), etc. In contrast, a compound having 14 to 22 carbon atoms for introducing a long-chain alkyl group, specifically, a long-chain alkylglycidyl ester of the following formula (II) The ether can be obtained by contact 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 hydrophobic modified alkyl cellulose of the present invention is preferably about 0.1 to 5.0% by mass with respect to the entire hydrophobic modified alkyl cellulose. . In order to obtain such a content, the molar ratio in the reaction between the water-soluble cellulose ester derivative and the long-chain alkyl glycidyl ether, the reaction time, the type of alkali catalyst, and the like may be selected as appropriate. After the reaction, a purification step such as neutralization, filtration, washing, drying, and sieving of the reaction product may be performed.

Of the above water-soluble cellulose ether derivatives, it is particularly preferable to select hydroxypropylmethylcellulose (wherein R in formula (I) represents a hydrogen atom, a methyl group, a group — [CH ₂ CH ( CH ₃ ) O] _m H and any of the four groups of the group —CH ₂ CH (OH) CH ₂ OR ′, q of the group A becomes 1, and the A becomes a methylene group).
Further, R ′ in the long-chain alkyl glycidyl ether of the 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 H ₃₇ ). When the number of carbon atoms of the alkyl group R ′ is less than 14 or 23 or more, the emulsion stability by the obtained hydrophobically modified alkyl cellulose is not sufficient.

The weight average molecular weight of the hydrophobically modified alkyl cellulose is preferably 100,000 to 1,000,000, more preferably 300,000 to 800,000, and still more preferably 550,000 to 750,000.
In the present invention, stearoxy hydroxypropyl cellulose is most preferably used as the hydrophobically modified alkyl cellulose, and a commercially available product can also be used. For example, Sangelose 90L (display name: hydrophobized hydroxypropyl methylcellulose; manufactured by Daido Kasei Kogyo Co., Ltd.), Natrosol Plus 330cs (manufactured by Ashland), Polysurf 67cs (manufactured by Ashland), and the like.

  The blending amount of the hydrophobically modified alkyl cellulose (A) in the emulsified cosmetic 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 emulsification stability cannot be obtained, and even if it exceeds 1% by mass, it is difficult to further increase the effect.

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

  In the emulsified cosmetic of the present invention, 55% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more of the oil (B) is used as a polar oil. The emulsion stability can be further improved. The upper limit value of the proportion of polar oil in the oil is not particularly limited. For example, polar oil may occupy 90% or more, and 100% of oil may be polar oil.

The “polar oil” in the present specification is not particularly limited as long as it has a high polarity among oil components generally used in cosmetics. For example, an oil having a relative dielectric constant of about 5 or more, preferably about 10 or more. Is preferably used.
Representative examples of polar oils in the emulsified cosmetic of the present invention include ester oils and ultraviolet absorbers. Moreover, by containing a larger amount of polar oil than conventional emulsified cosmetics, for example, highly polar fragrances can be stably blended.

  Specific examples of ester oils suitable for the emulsified cosmetics of the present invention include tripropylene glycol dineopentanoate, isononyl isononanoate, isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, lauric acid Hexyl, myristyl myristate, decyl oleate, hexyl decyl 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, dii malate Stearyl, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, pentaerythrityl tetra-2-ethylhexanoate, triethylhexanoin (tri-2-ethylhexane) Acid glycerin), trioctanoic acid glycerin, triisopalmitic acid glycerin, triisostearic acid trimethylolpropane, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, trimyristic acid glycerin, tri-2-heptylundecanoic acid glyceride, castor Oil fatty acid methyl ester, oleyl oleate, acetoglyceride, 2-heptylundecyl palmitate, diisobutyl adipate, N-lauroyl-L-glutamic acid-2- Cutyldecyl 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, triethyl citrate and the like.

  As the ultraviolet absorber, high polarity oil-based ultraviolet absorbers generally used in cosmetics can be widely used, and are not particularly limited. For example, benzoic acid derivatives, salicylic acid derivatives, cinnamic acid derivatives, dibenzoylmethane derivatives, β, β-diphenyl acrylate derivatives, benzophenone derivatives, benzylidene camphor derivatives, phenylbenzimidazole derivatives, triazine derivatives, phenylbenzotriazole derivatives, anthranyl derivatives And imidazoline derivatives, benzalmalonate derivatives, 4,4-diarylbutadiene derivatives and the like. Specific examples and product names are listed below, but are not limited thereto.

  Examples of benzoic acid derivatives include para-aminobenzoic acid (PABA) ethyl, ethyl-dihydroxypropyl PABA, ethylhexyl-dimethyl PABA (for example, “Escalol 507”; ISP), glyceryl PABA, PEG-25-PABA (for example, “Ubinal). P25 "; BASF), diethylaminohydroxybenzoyl hexyl benzoate (for example," Ubinal A plus ") and the like.

  Examples of salicylic acid derivatives include homosalate (“Eusolex HMS”; Rona / EM Industries), ethylhexyl salicylate (eg, “NeoHeliopan OS”; Herman & Reimer), dipropylene glycol Examples include salicylates (for example, “Dipsal”; Skell), TEA salicylates (for example, “Neo Heliopan TS”; Herman and Reimer).

Cinnamic acid derivatives include octyl methoxycinnamate or ethyl hexyl methoxycinnamate (eg “Pulsol MCX”; Hoffman-La Roche), isopropyl methoxycinnamate, isoamyl methoxycinnamate (eg “Neo Heliopan E1000”). Herman & Reimer), cinnoxate, DEA methoxycinnamate, diisopropyl methylcinnamate, glyceryl-ethylhexanoate-dimethoxycinnamate, di- (2-ethylhexyl) -4'-methoxybenzalmalonate, etc. Is exemplified.
Examples of the dibenzoylmethane derivative include 4-tert-butyl-4′-methoxydibenzoylmethane (for example, “Pulsol 1789”).

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

Examples of benzylidene camphor derivatives include 3-benzylidene camphor (eg, “Mexoryl SD”; Simex), 4-methylbenzylidene camphor, benzylidene camphorsulfonic acid (eg, “Megizolyl SL”; Simex), methosulfate camphor benzalco Examples thereof include nium (for example, “Megizolyl SO”; Simex), terephthalylidene dihydrogen sulfonic acid (for example, “Megizolyl SX”; Simex), polyacrylamide methylbenzylidene camphor (for example, “Megizolyl SW”; Simex), and the like. .
Examples of the phenylbenzimidazole derivatives include phenylbenzimidazole sulfonic acid (for example, “USOLEX 232”; Merck & Co., Inc.), phenyl dibenzimidazole tetrasulfonate disodium (for example, “Neo Heliopan AP”; Herman & Reimer) and the like. Illustrated.

Examples of the triazine derivatives include anisotriazine (eg, “Tinosorb S”; Ciba Specialty Chemicals), ethylhexyl triazone (eg, “Ubinal T150”; BASF), and diethylhexylbutamide triazone (eg, “Tinosorb S”). Uvasorb HEB ”(Sigma 3V), 2,4,6-tris (diisobutyl-4′-aminobenzalmalonate) -s-triazine and the like are exemplified.
Examples of phenylbenzotriazole derivatives include drometrizole trisiloxane (eg “Silatrizole”; Rhodia Shimmy), methylenebis (benzotriazolyl tetramethylbutylphenol) (eg “Tinosorb M” (Ciba Specialty Chemicals))) and the like.
Examples of anthranyl derivatives include menthyl anthranilate (for example, “Neo Heliopan MA”; Herman & Reimer).
Examples of the imidazoline derivative include ethylhexyl dimethoxybenzylidene dioxoimidazoline propionate.
Examples of the benzalmalonate derivative include polyorganosiloxane having a benzalmalonate functional group (for example, Polysilicone-15; “Pulsol SLX”; DSM Nutrition Japan).
Examples of the 4,4-diarylbutadiene derivative 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 oils generally blended in cosmetics, for example, having a relative dielectric constant of about 5 It can be set as 1 type, or 2 or more types selected from less than oil components.

The blending amount of the ultraviolet absorber contained in the polar oil is, for example, 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more of the polar oil.
As a compounding quantity with respect to the whole emulsified cosmetics of a ultraviolet absorber, it is 5-25 mass%, Preferably it is 8-23 mass%, More preferably, it is 10-20 mass%.

The nonpolar oil blended in the emulsified cosmetic 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 chain silicone oils such as polydimethylsiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and cyclic silicone oils such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, Examples include hydrocarbon oils such as decane, dodecane, isododecane, isohexadecane, liquid paraffin, squalane, squalene, and paraffin.

As the base material for the ultraviolet light scattering agent (C) having a hydrophobic surface in the emulsified cosmetic of the present invention, zinc oxide or titanium oxide powder is preferably used.
The zinc oxide and titanium oxide used in the present invention are not particularly limited and can be appropriately selected from those usually 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 a substrate surface such as zinc oxide or titanium oxide.
Surface hydrophobization treatment includes silicone treatment such as methylhydrogenpolysiloxane and methylpolysiloxane; fluorine treatment with perfluoroalkyl phosphate ester, perfluoroalcohol, etc .; amino acid treatment with N-acylglutamic acid, etc .; Treatment; metal soap treatment; fatty acid treatment; alkyl phosphate ester treatment and the like.

  The blending amount of the ultraviolet scattering agent (C) having a hydrophobic surface in the emulsified cosmetic of the present invention is 2.5 to 30% by mass, preferably 3 to 30% by mass, more preferably 4 to 20% by mass. When the blending amount is less than 2.5% by mass, it is difficult to obtain a high SPF value as compared with the conventional case, and there is a tendency that a unique and fresh feeling at the time of application cannot be obtained. On the other hand, when it exceeds 30 mass%, emulsion stability and usability may be reduced.

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

  Specific examples include vinyl polymers such as polyvinyl alcohol, polyvinyl acetate, polyvinyl methyl ether, polyvinyl pyrrolidone, vinyl pyrrolidone and vinyl acetate copolymer, carboxy vinyl polymer; sodium polyacrylate, polyethyl acrylate, alkanol polyacrylate Amine, copolymer of alkyl methacrylate and dimethylaminoethyl methacrylate, poly-2-acrylamido-2-methylpropanesulfonic acid, polymethacryloyloxytrimethylammonium, (acryloyldimethyltaurine ammonium / VP) copolymer, dimethylacrylamide / acryloyldimethyltaurine Na) cloth Examples thereof include acrylic high molecules such as polymers.

  However, among thickeners with low salt resistance (viscosity decreases due to increase in electrolyte concentration), compared to thickeners that thicken by entanglement of polymer chains, water-swellable microgels in the aqueous phase It is preferable to use a thickening agent of a type that forms a thickening layer by friction between swollen microgel particles, since it can further suppress the sliminess when the cosmetic is applied to the skin. This is because the hydrophobically modified alkyl cellulose blended as an emulsifier also has a thickening action due to the entanglement of polymer chains, so if a thickener of the type that thickens by the same mechanism is further blended, the thickening action is promoted. This is because it can cause sliminess.

  The blending amount of the water phase thickener (D) having low salt resistance in the emulsified cosmetic 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. If it is less than 0.05% by mass, the function as a thickener (viscosity adjustment and emulsion stabilization) is not exhibited, and a unique and fresh feel during coating cannot be obtained. When it exceeds 3 mass%, stickiness and sliminess may occur.

  In addition to the essential components (A) to (D) described above, the emulsified cosmetic of the present invention can be blended with 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; glycerin such as glycerin, diglycerin, and polyglycerin. Sugar sugars such as sorbitol, mannitol, maltitol, xylitol, erythritol; sugars such as fructose, glucose, galactose, maltose, lactose, trehalose; natural pigments such as chlorophyll, β-carotene; gum arabic, gum tragacanth, galactan, Plant polymers such as guar gum, carob gum, caraya gum, gellan gum, carrageenan; microbiology such as xanthan gum, dextran, succinoglucan, pullulan Animal polymers such as collagen, casein, albumin and gelatin; starch polymers such as carboxymethyl starch and methylhydroxypropyl starch; methylcellulose, ethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, sodium cellulose sulfate, hydroxy Cellulose polymers such as propylcellulose, sodium carboxymethylcellulose and crystalline cellulose; alginic acid polymers such as sodium alginate and propylene glycol alginate; other thickeners; magnesium ascorbate phosphate, glucoside ascorbate, vitamin B6 hydrochloride Vitamins such as pantothenyl ethyl ether; drugs such as bactericides, anti-inflammatory agents, preservatives, plant extracts, amino acids, cooling agents; Examples include, but are not limited to, lower alcohols such as ethanol and isopropyl alcohol; aromatic alcohols such as phenoxyethanol and benzyl alcohol; surfactants and the like.

The emulsified cosmetic of the present invention is an oil-in-water emulsified composition by using hydrophobically modified alkyl cellulose as an emulsifier, while the internal phase (oil phase) contains a polar oil containing an ultraviolet absorber and an ultraviolet scattering material having a hydrophobic surface. The agent can be blended higher than conventional oil-in-water cosmetics and exhibits excellent UV protection. Furthermore, when the proportion of polar oil, which has been considered to be a cause of destabilization in the past, is 55% by mass or more of the oil phase, there is a surprising effect that the emulsion stability is improved.
On the other hand, since hydrophobically modified alkyl cellulose has an appropriate emulsifying power, the UV scattering agent blended in the internal phase (oil phase) is likely to interact with the external phase (aqueous phase), especially when applied to the skin. It is considered that an electrolyte (such as an ultraviolet scattering agent) coming out of the material can be brought into contact with a thickener in the aqueous phase to rapidly reduce the viscosity, thereby giving a unique and fresh feel that melts. Therefore, the emulsified cosmetic of the present invention preferably contains substantially no emulsifier other than the hydrophobically modified alkyl cellulose, particularly an emulsifier having a 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 usually used for oil-in-water emulsified cosmetics. That is, it can be prepared by mixing the water phase component and the oil phase component separately, and adding and emulsifying the oil phase component while stirring the water phase component.

  The emulsified cosmetic of the present invention is not particularly limited, but it is usually preferable to have an internal phase (oil phase) having an average particle diameter of about 15 μm or less.

Hereinafter, the present invention will be described in more detail with reference to specific examples, but these do not limit the technical scope of the present invention.
In addition, the compounding quantity in a following example etc. is the mass% unless it mentions specially.

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

1. Evaluation method of use feeling Each sample of the examples and comparative examples was actually used by five professional panels, and the use feeling was evaluated. Each panel was evaluated in five stages according to the following evaluation point criteria, and the total score was determined based on the following evaluation criteria.
"Evaluation item"
(1) Unique and fresh feeling of use As defined above, it is possible to obtain a feeling that the viscosity suddenly drops and collapses when applied to the skin and a feeling of spreading freshness to the skin.
(2) Feeling slimy when blending Do not feel slimy when the applied cosmetics are blended into the skin.
“Evaluation criteria”
5: Very good 4: Excellent 3: Normal 2: Inferior 1: Very inferior “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. Emulsification stability The sample was filled in two screw tubes (50 ml) and left in a thermostatic bath at 0 ° C. or 50 ° C. for 2 weeks. Before and after standing, the change in viscosity was measured using a rotary viscometer (bismetron rotary viscometer), and the emulsified particles and the appearance were observed.
"Evaluation criteria"
A: No decrease in viscosity was observed at any temperature level of 0 ° C. and 50 ° C., and there was no problem in emulsified particles and appearance.
B: A slight decrease in viscosity or increase in emulsified particles and change in appearance were observed at any temperature level.
C: A slight decrease in viscosity, increase in emulsified particles, and change in appearance were observed at any temperature level.
D: Significant decrease in viscosity, increase in emulsified particles, and change in appearance were observed at any temperature level.
E: At any temperature level, a significant decrease in viscosity, an increase in emulsified particles, and a change in appearance were observed.

  From the results shown in Table 1, a highly polar UV absorber and a hydrophobic surface-treated UV scattering agent were added to the oil phase using hydrophobically modified alkyl cellulose as an emulsifier, and the aqueous phase was increased with a thickener with low salt resistance. The viscous oil-in-water emulsified cosmetics (Examples 1 to 5) obtained a unique and fresh use feeling at the time of application, but in Comparative Example 1 in which the blending amount of the ultraviolet scattering agent was less than the predetermined value, The viscosity was insufficient to decrease, and the intended use feeling was not obtained. In addition, even in the emulsified cosmetic obtained by thickening the aqueous phase with a thick salt-resistant thickener, a unique and fresh use feeling cannot be obtained.

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

  In Examples 9 to 11 in which the polar oil blended in Example 6 was replaced with another polar oil, a unique feeling of use was obtained as in Example 6, and the emulsion stability was also excellent.

  In Examples 1 to 11 shown in Tables 1 to 3, the proportion of polar oil in the total amount of oil exceeded 55% and showed extremely excellent emulsification stability, but the proportion of polar oil in the total amount of oil was In Examples 12 to 14 in which the content was less than 55%, the emulsion stability was somewhat reduced (however, there was no problem in practical use). 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 and fresh feeling of use was somewhat lowered. . This is presumably because a part of the electrolyte was trapped by the chelating agent and the sudden decrease in viscosity was somewhat inhibited. Therefore, it is presumed that it is preferable to minimize the chelating agent to be blended in the emulsified cosmetic of the present invention.

  From the results shown in Table 5, Examples 16 to 19 in which hydrophobically modified alkyl cellulose was used as an emulsifier, the aqueous 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. In addition, it is further confirmed that a unique and fresh feeling of use is obtained regardless of the type of UV scattering agent substrate and surface treatment agent having a hydrophobic surface blended in the oil phase, and the emulsion stability is also extremely excellent. It was done.

(Example 20)
An oil-in-water emulsified sunscreen cosmetic with the composition shown below was prepared. The resulting cosmetic gave a unique fresh feel that melted when applied to the skin, and the SPF after application was about 55.
Compounding ingredients Compounding 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) Diethylaminohydroxybenzoyl hexyl benzoate 2.00
(11) Bisethylhexyloxyphenol methoxyphenyl triazine
1.50
(12) Cetyl ethylhexanoate 3.00
(13) Triethoxycaprylylsilane 0.70
(14) (Dimethylacrylamide / acryloyldimethyltaurine Na) cross polymer
0.30
(15) Fragrance 0.05

The present invention includes the following embodiments (1): (A) 0.05 to 1% by mass of hydrophobically modified alkyl cellulose;
(B) 5-40 mass% oil content;
(C) an ultraviolet scattering agent having a hydrophobic surface of 2.5 to 30% by mass; and (D) an aqueous phase thickener having low salt resistance,
The oil-in-water emulsified cosmetic characterized in that the ultraviolet scattering agent (C) is dispersed in an oil phase.
(2): The cosmetic according to (1), wherein the (A) hydrophobically modified alkylcellulose is a hydrophobized hydroxypropylmethylcellulose.
(3): The (D) thickening agent with low salt resistance is a type of thickening agent that forms a water-swellable microgel in the aqueous phase and thickens by friction between swollen microgel particles. The cosmetic according to (1) or (2).
(4) The cosmetic according to (1) or (2), wherein the water phase thickener (D) having a low salt resistance is made of a vinyl polymer or an acrylic 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 component (B).
(6) The cosmetic according to any one of (1) to (5), which is a sunscreen cosmetic.

Claims (1)

Invention described in the specification