Oil-in-water emulsion cosmetic

Abstract

[Problem] The purpose of the present invention is to provide an oil-in-water emulsion cosmetic into which an oil-soluble chemical can be stably blended and that feels excellent when used. [Solution] This oil-in-water emulsion cosmetic is characterized by comprising (A) a polymer thickener having a hydrophobic group, (B) an oil-soluble chemical, (C) a polyoxyethylene hydrogenated castor oil having an average number of moles of ethylene oxide added of 30 to 80, and (D) polypropylene glycol.

Description

Oil-in-water emulsion cosmetics

[0001] The present invention relates to an oil-in-water emulsion cosmetic that contains an oil-soluble drug stably and has an excellent feel when used.

[0002] Cosmetics such as creams and emulsions are made possible by various emulsification technologies, which allow for the stable blending of an aqueous phase containing water-based ingredients such as moisturizers and an oil phase containing oily ingredients such as oils. These emulsification technologies have a significant impact not only on the stability of the formulation, but also on the appearance and feel of the product, so they are used appropriately to achieve the functionality and usability desired by consumers.

[0003] For example, in oil-in-water emulsion cosmetics, the use of polymer emulsions allows the refreshing feeling and moist feel characteristic of oil-in-water emulsions to be maintained, while the use of gel-based emulsions allows for a rich, thick feel despite being an oil-in-water emulsion.

[0004] Furthermore, in cosmetics, oil-soluble drugs are blended to impart functions such as wrinkle improvement, anti-aging, and whitening effects. In this case, techniques such as blending a large amount of oil or specifying the type of oil may be required to increase the stability of the oil-soluble drug. For example, Patent Document 1 discloses that a certain amount of oil (preferably 8 to 20% by mass) is blended to contain a higher fatty acid having 8 to 20 carbon atoms and / or a higher alcohol having 8 to 20 carbon atoms, and a layered gel structure is formed by polyoxyethylene phytosterol and glycerin fatty acid diester, thereby making it possible to stably retain the oil-soluble drug in an oil-in-water emulsion cosmetic.

[0005] Generally, oil-in-water emulsion cosmetics produced by polymer emulsification are preferred as bases for skin care cosmetics because they are non-sticky and provide a refreshing feel when used. However, because polymer emulsions have a relatively weak emulsifying power, when a large amount of oil is blended into an oil-in-water emulsion cosmetic produced by polymer emulsification, there is a problem that oil floating and coalescence of emulsion particles are likely to occur. Therefore, when oil-soluble drugs are blended into an oil-in-water emulsion cosmetic, a gel-type emulsion with high emulsifying power is often used, which limits the feel of use to a thick and heavy feel.

[0006] Therefore, there has been a problem in stably incorporating oil-soluble drugs while maintaining the feel of use of oil-in-water emulsion cosmetics produced by polymer emulsification.

[0007] JP 2009-051810

[0008] An object of the present invention is to provide an oil-in-water emulsion cosmetic prepared by polymer emulsification, in which an oil-soluble drug is stably blended.

[0009] As a result of extensive research into solving the above-mentioned problems, the present inventors discovered that by blending polypropylene glycol and a specific polyoxyethylene hydrogenated castor oil with an oil-in-water emulsion cosmetic prepared by polymer emulsification, it is possible to obtain an oil-in-water emulsion cosmetic that stably retains oil-soluble drugs and does not cause oil floating, thereby completing the present invention.

[0010] That is, the present invention provides an oil-in-water emulsion cosmetic comprising: (A) a polymeric thickener having a hydrophobic group; (B) an oil-soluble drug; (C) polyoxyethylene hydrogenated castor oil having an average number of moles of ethylene oxide added of 30 to 80; and (D) polypropylene glycol.

[0011] By adopting the above-described configuration, the oil-in-water emulsion cosmetic according to the present invention can stably retain an oil-soluble drug in the oil-in-water emulsion cosmetic by polymer emulsification and can prevent oil floating. The present invention makes it possible to realize an oil-in-water emulsion cosmetic containing an oil-soluble drug that has a refreshing feel when used without stickiness. Furthermore, when a retinol is used as the oil-soluble drug (B) of the present invention, the effect of suppressing skin irritation caused by the retinol is achieved.

[0012] The oil-in-water emulsion cosmetic of the present invention is characterized by containing (A) a polymeric thickener having a hydrophobic group, (B) an oil-soluble drug, (C) a specific polyoxyethylene hydrogenated castor oil, and (D) polypropylene glycol. Each of the components constituting the oil-in-water emulsion cosmetic of the present invention will be described in detail below.

[0013] <(A) Polymeric thickener having hydrophobic group> The polymeric thickener having hydrophobic group (hereinafter, sometimes referred to as "component (A)") used in the present invention means a thickener having a structure in which a hydrophobic group (lipophilic group) is introduced into the chain of a water-soluble polymer, and includes copolymers and crosspolymers containing at least one monomer having a hydrophobic group.Specific examples of component (A) of the present invention include acrylic acid / alkyl methacrylate polymers, polymers of (meth)acryloyldimethyltaurate and (meth)acrylic acid polyoxyethylene alkyl ether, hydrophobically modified alkyl cellulose, and hydrophobically modified polyether urethane.

[0014] The acrylic acid / alkyl methacrylate polymer is not particularly limited, but typically includes one having an alkyl chain with 5 to 40 carbon atoms, and preferably one having an alkyl chain with 10 to 30 carbon atoms. Specifically, what is called an (acrylates / alkyl acrylate (C10-30)) crosspolymer is preferably used. An example of a commercially available product is PEMULEN (registered trademark) TR-2 (manufactured by Lubrizol Corporation).

[0015] As the polymer of (meth)acryloyldimethyltaurate and polyoxyethylene alkyl ether (meth)acrylate, (ammonium acryloyldimethyltaurate / beheneth-25 methacrylate) crosspolymer is preferably used, and a commercially available product thereof is Aristoflex (registered trademark) HMB (manufactured by Clariant Japan K.K.).

[0016] The hydrophobically modified alkyl cellulose is represented by the following formula (I).

[0017] In the above formula (I), R is a bonding group R １ -R ２ and R １ may be the same or different within a molecule, and —[CH ２ CH (CH ３ ) O] ｒ -, -[CH ２ CH ２ O] ｒ - and -[CH ２ CH(OH)CH２ O]r- (wherein r is an integer of 0 to 4), and R ２ is one or more groups selected from a hydrocarbon group having 12 to 28 carbon atoms (preferably an alkyl group having 1 to 4 carbon atoms) and a hydrogen atom, and R ２ At least one of A is a hydrocarbon group having 12 to 28 carbon atoms (preferably an alkyl group having 1 to 4 carbon atoms). A is a group -(CH ２ ) ｔ - (t is an integer of 1 to 3), and s is a number of 100 to 10,000.

[0018] The hydrophobically modified alkyl cellulose of formula (I) has a structure in which a long-chain alkyl group, which is a hydrophobic group, is introduced into a water-soluble cellulose ether derivative via a polyoxyalkylene chain. Examples of the water-soluble cellulose ether derivative that serves as the molecular base include methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose, and can be obtained by reacting these with a long-chain alkyl glycidyl ether (for example, one represented by the following formula (I')). In formula (I'), R' is an alkyl group having 10 to 28 carbon atoms, preferably an alkyl group having 12 to 22 carbon atoms.

[0019] As the water-soluble cellulose ether derivative, hydroxypropyl methylcellulose or hydroxyethyl cellulose is preferred, and it is particularly preferred to select hydroxypropyl methylcellulose. Furthermore, R' of the long-chain alkyl glycidyl ether (above formula (I')) is preferably a stearyl group (-C １８ H ３７ ) or cetyl group (-C １６ H ３３ ) (in these cases, -CH ２ CH(OH)CH ２ OR' is -CH ２ CH(OH)CH ２ O-C １８ H ３７ or -CH ２ CH(OH)CH２ O-C １６ H ３３ (This becomes.)

[0020] The hydrophobically modified alkyl cellulose used in the present invention is preferably hydroxypropyl methylcellulose stearoxy ether, in which the hydrophobic group R' in formula (I') is a stearyl group. Commercially available products of this type include Sangelose 90L, 90M, 90H, 60L, 60M, and 60H (all manufactured by Daido Chemical Industry Co., Ltd.).

[0021] The hydrophobically modified polyether urethane refers to an associative thickener represented by the following formula (II): ３ -{(O-R ４ ) ｋ -OCONH-R ５ [-NHCOO-(R ６ -O)n-R ７ ] ｈ} ｍ (II) In the above formula (II), R ３ , R ４ and R ６ R each independently represents an alkylene group having 2 to 4 carbon atoms or a phenylethylene group, preferably an alkylene group having 2 to 4 carbon atoms. ５ represents an alkylene group having 1 to 10 carbon atoms which may have a urethane bond. ７ represents a linear, branched, or secondary alkyl group having 8 to 36 carbon atoms, preferably 12 to 24 carbon atoms. m is a number of 2 or more, preferably 2. h is a number of 1 or more, preferably 1. k is a number of 1 to 500, preferably a number of 100 to 300. n is a number of 1 to 200, preferably a number of 10 to 100.

[0022] The hydrophobically modified polyether urethane used in the present invention is a (PEG-240 / decyltetradeceth-20 / HDI) copolymer (a copolymer represented by the above formula (II), R ３ = ethyl group, R ４ and R ６ are each an ethylene group, R ５ = hexamethylene group, R ７= 2-decyltetradecyl group, h = 1, m = 2, k = 120, n = 20). Commercially available products of the copolymer include ADEKA NOL GT700 and ADEKA NOL GT730 (both manufactured by ADEKA Corporation).

[0023] The component (A) can be one or more selected from the above. As the component (A) of the present invention, it is preferable to use one or more selected from an acrylic acid / methacrylic acid alkyl polymer, a polymer of (meth)acryloyldimethyltaurate and (meth)acrylic acid polyoxyethylene alkyl ether, and a hydrophobically modified alkyl cellulose, and it is more preferable to use one or more selected from an acrylic acid / methacrylic acid alkyl polymer, and a polymer of (meth)acryloyldimethyltaurate and (meth)acrylic acid polyoxyethylene alkyl ether.

[0024] The amount of component (A) in the cosmetic of the present invention is not particularly limited, as long as it is an amount typically used in oil-in-water emulsion cosmetics to ensure emulsion stability. For example, examples of lower limits for the amount relative to the total amount of the cosmetic include 0.01% by mass or more, 0.02% by mass or more, and 0.03% by mass or more, and examples of upper limits for the amount relative to the total amount of the cosmetic include 0.3% by mass or less, 0.2% by mass or less, and 0.1% by mass or less. Therefore, examples of ranges for the amount include 0.01 to 0.3% by mass, 0.02 to 0.2% by mass, etc.

[0025] <(B) Oil-Soluble Drug> The (B) oil-soluble drug (hereinafter, may be simply referred to as "component (B)") used in the present invention may be any component that is typically blended as an active ingredient in pharmaceuticals, cosmetics, etc., such as a wrinkle-improving active ingredient, an antioxidant, an emollient, or a whitening agent, as long as it is soluble in oil.

[0026] Specific examples of active ingredients used in pharmaceuticals and cosmetics include vitamin A and its derivatives and salts thereof, vitamin E and its derivatives and salts thereof, oil-soluble derivatives of water-soluble vitamins, ceramides, and oil-soluble chamomile extracts.

[0027] Examples of vitamin A and its derivatives include carotene, lycopene (provitamin A), astaxanthin, lutein, and retinols, and examples of retinols include retinol (vitamin A), retinal (vitamin A aldehyde), retinoic acid (vitamin A acid), and vitamin A fatty acid esters, such as retinol acetate (vitamin A acetate ester), retinol palmitate (vitamin A palmitate ester), retinol propionate (vitamin A propionate ester), and retinol linoleate.

[0028] Examples of vitamin E and its derivatives include tocopherol (dl-α-tocopherol, d-δ-tocopherol), tocopherol acetate, tocopherol nicotinate, and tocopherol linoleate.

[0029] Examples of oil-soluble derivatives of water-soluble vitamins include oil-soluble pyridoxine derivatives (oil-soluble derivatives of vitamin B6) such as pyridoxine dicaprylate, pyridoxine dipalmitate, pyridoxine tripalmitate, pyridoxine trishexyldecanoate, and pyridoxine tri-2-hexyldecanoate, and oil-soluble ascorbic acid derivatives (oil-soluble derivatives of vitamin C) such as ascorbyl dipalmitate, ascorbyl stearate, ascorbyl tetra-2-hexyldecanoate, and ascorbyl palmitate.

[0030] Examples of the salts of the above vitamins include alkali metal salts (e.g., sodium salts, potassium salts, lithium salts, etc.), alkaline earth metal salts (e.g., calcium salts, magnesium salts, etc.), ammonium salts, and organic amine salts (e.g., monoethanolamine salts, diethanolamine salts, triethanolamine salts, etc.).

[0031] Examples of ceramides include N-(ω-acyloxy)acylsphingosine, N-acylsphingosine, N-acylphytosphingosine, N-(α-hydroxy)acylsphingosine, N-acyldihydrosphingosine, N-[ω-(α-hydroxy)acyloxy]acylsphingosine, and N-(α-hydroxy)acylphytosphingosine.

[0032] The oil-soluble chamomile extract refers to an extract obtained by adding a lipophilic organic solvent to dried chamomile flowers and appropriately heating and stirring the mixture. A specific example is chamomile flower extract.

[0033] As component (B) of the present invention, one or more selected from the above can be used. Among them, the cosmetic composition according to the present invention is particularly suitable as a cosmetic base for blending retinols such as retinol, which are known to be difficult to maintain the stability of the drug itself, and therefore it is preferable to include a retinol as component (B).

[0034] The amount of component (B) in the cosmetic of the present invention is not particularly limited, as long as it is an amount typically blended in a cosmetic to achieve the desired effect. Examples of lower limits for the amount blended relative to the total amount of the cosmetic include 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, and 0.008% by mass or more, while examples of upper limits include 10% by mass or less, 8% by mass or less, and 5% by mass or less. Therefore, examples of the blending amount range include 0.001 to 10% by mass, 0.003 to 8% by mass, etc. If the blending amount is less than 0.001% by mass, the effectiveness of the oil-soluble drug will not be fully exerted, and if the blending amount exceeds 10% by mass, the oil-soluble drug may not be stably maintained.

[0035] <(C) Specific Polyoxyethylene Hydrogenated Castor Oil> The polyoxyethylene hydrogenated castor oil (C) used in the present invention (hereinafter sometimes simply referred to as "component (C)") is a compound typically used as a nonionic surfactant in cosmetics, and refers to a mixture of ethers and esters obtained by addition polymerization of hydrogenated castor oil (hydrogenated castor oil) with an average mole number of ethylene oxide of about 30 to about 80. Specific examples include PEG-30 hydrogenated castor oil, PEG-40 hydrogenated castor oil, PEG-50 hydrogenated castor oil, PEG-60 hydrogenated castor oil, and PEG-80 hydrogenated castor oil. Of these, it is preferable to use polyoxyethylene hydrogenated castor oil having an average mole number of ethylene oxide added of 40 to 60.

[0036] The amount of component (C) in the cosmetic of the present invention is not particularly limited as long as it is an amount normally used in cosmetics, but is preferably 0.1 to 2.0 mass% and more preferably 0.2 to 1.0 mass% relative to the total amount of the cosmetic. If it is less than 0.1 mass%, oily floating tends to occur, and if it exceeds 2.0 mass%, stickiness tends to occur, which may impair the feel when used.

[0037] <(D) Polypropylene Glycol> The (D) polypropylene glycol (hereinafter sometimes simply referred to as "component (D)") used in the present invention is a polymer of propylene glycol, and is not particularly limited as long as it is a polypropylene glycol (PPG) commonly used in cosmetics. Examples of the (D) polypropylene glycol of the present invention include those having an average molecular weight of approximately 400 to 3000, such as PPG400 (average molecular weight approximately 400), PPG1000 (average molecular weight approximately 1000), PPG1200 (average molecular weight approximately 1200), PPG1500 (average molecular weight approximately 1500), PPG2000 (average molecular weight approximately 2000), and PPG3000 (average molecular weight approximately 3000). Of these, those with a degree of polymerization of 15 to 20, or an average molecular weight of approximately 800 to 1200, are preferred. As component (D) of the present invention, one or more polypropylene glycols selected from those with different average molecular weights may be used.

[0038] From the viewpoint of suppressing oil floating, the blending amount of component (D) in the cosmetic of the present invention is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, relative to the total amount of the cosmetic. The upper limit of the blending amount is not particularly limited as long as it does not impair the quality of the oil-in-water emulsion cosmetic of the present invention, and examples include 10% by mass or less, 8% by mass or less, and 6% by mass or less. Examples of blending amount ranges include 0.1 to 10% by mass, 0.2 to 8% by mass, and 0.3 to 6% by mass.

[0039] In the cosmetic of the present invention, the blending mass ratio (D / B) of the polypropylene glycol (D) to the oil-soluble drug (B) is preferably 1 to 100, and more preferably 4 to 100. There are no particular restrictions on the blending amounts of the components (B) and (D), but it has been confirmed herein that the effects of the present invention can be obtained when the above ranges are satisfied.

[0040] The oil component constituting the cosmetic according to the present invention is not particularly limited as long as it is an oil component commonly used in cosmetics, and examples thereof include ester oil, hydrocarbon oil, higher fatty acid having 12 to 28 carbon atoms, higher alcohol having 12 to 22 carbon atoms, oils and fats that are liquid at room temperature of about 25°C, oils and fats that are solid or semi-solid at room temperature of about 25°C, waxes, silicone oil, etc.

[0041] Specific examples of ester oils include isopropyl myristate, cetyl ethylhexanoate, octyldodecyl myristate, isopropyl palmitate, ethylhexyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, lanolin acetate, isocetyl stearate, hexyldecyl isostearate, cholesteryl hydroxystearate, methyl ricinoleate, oleyl oleate, ethyl laurate, 2-hexyldecyl myristate, and palmitic Ester oils in which an acid such as hexyldecyl acetate, ethyl acetate, butyl acetate, or amyl acetate is bonded to a monohydric alcohol; ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glyceryl di(2-heptylundecanoate), trimethylolpropane triethylhexanoate, trimethylolpropane triisostearate, pentaerythrityl tetraethylhexanoate, triethylhexanoin, trimili Ester oils of polyhydric alcohols and acids such as glyceryl stearate, diisobutyl adipate, diheptylundecyl adipate, diethylhexyl sebacate, dihexyldecyl adipate, diisopropyl sebacate, and triethyl citrate; N-lauroyl-L-glutamic acid-2-octyldodecyl ester, di(phytosteryl / octyldodecyl) lauroyl glutamate, di(octyldodecyl / phytosteryl / behenyl) lauroyl glutamate, di(cholesteryl / octyldodecyl) lauroyl glutamate, Examples of suitable oils include ester oils in which a carboxyl group of an amino acid is ester-bonded to an alcohol via an ester bond, such as di(cholesteryl / behenyl / octyldodecyl) lauroyl glutamate and isopropyl lauroyl sarcosine; and diesters of dimer acids and / or dimer diols, such as dimer dilinoleate (phytosteryl / isostearyl / cetyl / stearyl / behenyl), di(isostearyl / phytosteryl) dimer dilinoleate, dimer dilinoleyl dimer dilinoleate, dimer dilinoleyl diisostearate, and acetoglyceride.

[0042] Specific examples of hydrocarbon oils include hydrogenated polydecene, liquid paraffin, squalane, paraffin, ceresin, and squalene. Specific examples of higher fatty acids having 12 to 28 carbon atoms include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, 12-hydroxystearic acid, isostearic acid, linoleic acid, and linolenic acid. Specific examples of higher alcohols having 12 to 22 carbon atoms include lauryl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, oleyl alcohol, monostearyl glycerol ether (batyl alcohol), monopalmityl glycerol ether, cholesterol, phytosterol, and isostearyl alcohol.

[0043] Specific examples of liquid oils and fats include avocado oil, camellia oil, macadamia nut oil, mink oil, olive oil, castor oil, and jojoba oil. Specific examples of solid oils and fats include cocoa butter, coconut oil, palm oil, palm kernel oil, beef tallow, lard, mutton tallow, horse oil, hydrogenated castor oil, Japan wax, and shea butter. Specific examples of waxes include beeswax, candelilla wax, cotton wax, carnauba wax, privet wax, spermaceti wax, montan wax, rice bran wax, lanolin, reduced lanolin, hard lanolin, kapok wax, sugarcane wax, jojoba wax, and shellac wax. Specific examples of silicone oils include linear silicone oils such as dimethicone, diphenylsiloxyphenyl trimethicone, hydrogen dimethicone, dodecamethylpentasiloxane, and decamethyltetrasiloxane, and cyclic silicone oils such as cyclomethicone, cyclohexasiloxane, and octamethylcyclotetrasiloxane.

[0044] The cosmetic of the present invention can use one or more oils selected from the above-mentioned oils, and it is particularly preferred to use one or more ester oils and hydrocarbon oils, and more specifically, it is preferred to use one or more pentaerythrityl tetraethylhexanoate, di(phytosteryl / octyldodecyl) lauroyl glutamate, and hydrogenated polydecene.

[0045] The amount of oil in the cosmetic of the present invention is not particularly limited, as long as the oil-soluble drug (B) is uniformly dissolved. For example, the amount is preferably 3 to 25% by mass, more preferably 4 to 20% by mass, and even more preferably 5 to 18% by mass, relative to the total amount of the cosmetic. If the amount is within the above range, the effects of the present invention are exhibited, no oil floating occurs, and a stable oil-in-water emulsion cosmetic can be obtained.

[0046] The water constituting the cosmetic of the present invention is not particularly limited as long as it is water that is commonly used in cosmetics, such as purified water, ion-exchanged water, tap water, etc. The blending amount is an amount based on the total amount of the oil-in-water emulsion cosmetic of the present invention, taking the total as 100%.

[0047] In the field of cosmetics, it is known that topical skin preparations containing retinols can irritate the skin upon application. The present inventors have discovered that when retinols are used as component (B) of the present invention, the irritation caused by retinols is suppressed in the oil-in-water emulsion cosmetic of the present invention. It is believed that the incorporation of component (D) in the oil-in-water emulsion cosmetic of the present invention suppresses the irritation caused by retinols.

[0048] Furthermore, during the course of research by the present inventors, it was confirmed that retinols tend to be more irritating to the skin, particularly when the amount of oil in which they dissolve is small. Therefore, from the perspective of suppressing the irritation caused by retinols, the total amount of oils blended in the oil-in-water emulsion cosmetic according to the present invention is preferably 10% by mass or less, and more preferably less than 10% by mass, of the total amount of the cosmetic.

[0049] In addition to the essential components (A) to (D) described above, the emulsion cosmetic of the present invention can appropriately contain other components that can be incorporated into oil-in-water emulsion cosmetics, provided that the effects of the present invention are not impaired. Specific examples of such components include thickeners other than component (A), humectants, lower alcohols having 5 or fewer carbon atoms, neutralizing agents, various chemicals, various extracts, chelating agents, antioxidants (e.g., tocopherol), preservatives (e.g., phenoxyethanol), stabilizers (e.g., dibutylhydroxytoluene (BHT)), masking agents, colorants, fragrances, and essential oils.

[0050] Examples of thickeners include xanthan gum, tamarind gum, sodium alginate, gellan gum, agar, polyvinyl alcohol, quince seed gum, and non-alkyl-modified carboxyvinyl polymers (herein simply referred to as "carbomers"), etc. Commercially available non-alkyl-modified carboxyvinyl polymers include, for example, CARBOPOL (registered trademark) 941 polymer, CARBOPOL (registered trademark) 980 polymer, CARBOPOL (registered trademark) 981 polymer (manufactured by Lubrizol Corporation), Sinthalen (registered trademark) K, and Sinthalen (registered trademark) L (manufactured by 3V Sigma).

[0051] Examples of moisturizing agents include 1,3-butylene glycol (BG), polyethylene glycol, propylene glycol, dipropylene glycol (DPG), hexylene glycol, glycerin, diglycerin, xylitol, maltitol, maltose, D-mannite, trehalose, erythritol, propanediol, glucose, and polyoxyethylene methyl glucoside. Examples of lower alcohols include ethanol and isopropyl alcohol. Examples of neutralizing agents include potassium hydroxide, sodium hydroxide, and aminomethylpropanol. Examples of chelating agents include edetate sodium salt (EDTA-3Na), sodium metaphosphate, and phosphoric acid.

[0052] Examples of various drugs include water-soluble vitamins such as inositol, pyridoxine hydrochloride, benzyl nicotinate, niacinamide, magnesium ascorbyl phosphate, ascorbic acid 2-glucoside, dl-α-tocopherol 2-L-ascorbyl phosphate diester potassium salt, pantothenic acid, and biotin; anti-inflammatory agents such as allantoin and azulene; whitening agents such as arbutin, 4-methoxysalicylic acid or a salt thereof, and tranexamic acid or a derivative thereof; astringents such as tannic acid; lysozyme chloride, γ-oryzanol, marine collagen, and marine elastin.

[0053] Examples of various extracts include ascañon extract, benanome extract, turmeric extract, houttuynia cordata extract, phellodendron bark extract, melilot extract, dead nettle extract, licorice extract, peony extract, soapwort extract, loofah extract, cinchona extract, saxifrage extract, sophora flavescens extract, watercress extract, soapberry extract, fennel extract, primrose extract, rose extract, rehmannia root extract, lemon extract, lithospermum root extract, aloe extract, thyme extract, eucalyptus extract, horsetail extract, sage extract, thyme extract, tea extract, Chinese tea extract, seaweed extract, cucumber extract, clove extract, raspberry extract, melissa extract, ginseng extract, carrot extract, horse chestnut extract, peach extract, peach leaf extract, mulberry extract, cornflower extract, witch hazel extract, placenta extract, thymus extract, silk extract, and yeast extract.

[0054] The emulsion cosmetic of the present invention can be produced according to conventional production methods, for example, by preparing oil phase components and aqueous phase components, and then stirring and emulsifying the oil phase and aqueous phase with a homomixer or the like.

[0055] The cosmetic of the present invention does not produce oily residue, can stably retain oil-soluble drugs, and has a refreshing feel when used. Taking advantage of these characteristics, the cosmetic of the present invention is suitable for use as a skin care lotion, emulsion, cream, serum, etc.

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, the blending amounts of the components are expressed in mass % relative to the system in which the components are blended.

[0057] Oil-in-water emulsion cosmetics were prepared with the compositions shown in Tables 1 to 3 below, and their appearances were evaluated according to the following evaluation methods and criteria. The evaluation results are also shown in the tables. All of the examples and comparative examples listed here are oil-in-water emulsion cosmetics that were emulsified by polymer emulsification (component (A) of the present invention) and contained an oil-soluble drug (B).

[0058] <Appearance Evaluation> After preparing each cosmetic, it was left to stand at 50°C for 4 weeks, then returned to room temperature (25°C), and the condition of the sample was visually observed and evaluated according to the following criteria. In the present invention, the stability of the preparation was evaluated based on the degree of oil floating. A: No oil floating was observed. B: Slight oil floating was observed. C: Significant oil floating was observed in some areas. D: Significant oil floating was observed overall.

[0059]

[0060] In Table 1, Comparative Example 1 is an example that does not contain the components (C) and (D) of the present invention, Comparative Example 2 is an example that uses PEG-10 dimethicone, a surfactant commonly used in oil-in-water emulsion cosmetics, instead of the component (C), and Comparative Example 3 is an example that does not contain the component (D). Furthermore, Comparative Example 4 is an example in which the component (D) is not blended and the amount of surfactant blended is increased, and Comparative Example 5 is an example in which the component (D) is not blended and the amount of thickener blended is increased to increase the viscosity of the entire system. Oil floating was observed in all Comparative Examples. On the other hand, the cosmetic of Example 1, which contains the components (C) and (D) of the present invention, did not experience oil floating and had excellent stability.

[0061]

[0062] Table 2 shows examples in which the polyoxyethylene hydrogenated castor oil and polymer thickener were changed. When PEG-20 hydrogenated castor oil and PEG-100 hydrogenated castor oil were used (Comparative Examples 6 and 7), oil floating was not sufficiently suppressed. Note that the effects of the present invention were also obtained when a polymer of (meth)acryloyldimethyltaurate and (meth)acrylic acid polyoxyethylene alkyl ether was used as component (A) of the present invention (Example 4).

[0063]

[0064] Table 3 shows examples in which the blending amounts of component (B), component (C), and component (D) of the present invention were varied. In all examples, oil-in-water emulsion cosmetics were obtained that were sufficiently suppressed from floating on oil and had excellent formulation stability.

[0065] Next, retinol-containing oil-in-water emulsion cosmetics having the compositions shown in Table 4 below were prepared, and their skin irritation was evaluated according to the following evaluation method and criteria. The evaluation results are also shown in the table. <Irritation Evaluation> A practical use test was conducted by 10 expert panelists. The prepared cosmetics were applied to the skin, and the skin irritation was evaluated according to the following criteria. A (very good): 8 or more out of 10 panelists responded that there was no irritation. B (good): 5 to 7 out of 10 panelists responded that there was no irritation. C (fairly good): 3 to 4 out of 10 panelists responded that there was no irritation. D (poor): 2 or less out of 10 panelists responded that there was no irritation.

[0066]

[0067] As shown in Table 4, many panelists felt irritation on their skin when they applied the cosmetic of Comparative Example 8, which did not contain the component (D) of the present invention. On the other hand, few panelists felt irritation when they applied the cosmetic of Examples 11 and 12, which contained the component (D) of the present invention, suggesting that the irritation to the skin caused by retinol was suppressed.

Claims

1. An oil-in-water emulsion cosmetic comprising: (A) a polymeric thickener having a hydrophobic group; (B) an oil-soluble drug; (C) polyoxyethylene hydrogenated castor oil having an average number of ethylene oxide moles added of 30 to 80; and (D) polypropylene glycol.

2. The oil-in-water emulsion cosmetic according to claim 1, wherein the blending mass ratio (D / B) of the component (D) to the component (B) is 1 to 100.

3. The oil-in-water emulsion cosmetic according to claim 1, wherein component (B) comprises a retinol.

4. The oil-in-water emulsion cosmetic according to claim 1, wherein component (A) is one or more selected from the group consisting of an acrylic acid / methacrylate alkyl polymer, a polymer of (meth)acryloyldimethyltaurate and polyoxyethylene alkyl ether (meth)acrylate, and a hydrophobically modified alkyl cellulose.

5. The oil-in-water emulsion cosmetic according to claim 1, wherein the amount of component (D) is 0.1% by mass or more based on the total amount of the cosmetic.

6. The oil-in-water emulsion cosmetic according to claim 1, wherein the total amount of oil is 10% by mass or less based on the total amount of the cosmetic.

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