JP7500355B2 - O/W type emulsion composition - Google Patents

Description

The present invention relates to an O/W type (oil-in-water type) emulsion composition. More specifically, the present invention relates to an O/W type emulsion composition that has an excellent feel when used on the skin and when applied.

Ceramide is an intercellular lipid present in the epidermis (stratum corneum) of human skin. It is known that ceramide in the stratum corneum decreases with aging, etc., which causes the skin to dry out and wrinkle, and the barrier function to be weakened, which allows the skin to be penetrated by allergens, resulting in inflammation and itching. Applying ceramide to the skin is effective against such symptoms, but when ceramide is added to a composition for external use, there are problems such as a poor feel when applied, stickiness, and poor skin compatibility. In addition, in areas where dryness and fine wrinkles are likely to occur, such as between the eyebrows, around the eyes, and around the mouth, the feel felt when applying a composition for external use and spreading it with the fingers (application feel) is important, and it is desirable to impart a feeling of application, specifically a feeling of initial resistance (a feeling of the emulsion composition retaining its shape) while gradually blending into the skin (also referred to as a "thickness" in this specification).

As a method for improving the feel of such topical compositions containing ceramide, a technique has been proposed (Patent Document 1) that makes the composition non-sticky and has a good feel by incorporating ceramide and a phosphate triester of a specific structure, but this is still not sufficient and there is room for improvement.

Patent Document 2 describes a technique for imparting a "richness" to an emulsion composition as a sensation similar to the aforementioned "thickness," but does not describe a method for imparting a "richness" to a topical composition that contains ceramide.

Japanese Patent Application Laid-Open No. 9-67224 JP 2011-21007 A

The object of the present invention is to provide an O/W type emulsion composition that has an excellent feeling of use and/or application to the skin, specifically, an O/W type emulsion composition that is not sticky during use and is compatible with the skin. Another object of the present invention is to provide an O/W type emulsion composition that has a unique application feeling (thickness) felt when applied to the skin and spread, separately from or in addition to the above-mentioned feeling of use.

The present inventors have conducted intensive research to solve the above problems, and have discovered that, as shown in the experimental examples described below, by combining (A) ceramides, (B) nonionic surfactants, (C) shea butter, and (D) water to prepare an O/W type emulsion composition, it is possible to obtain a topical composition that is excellent in the above-mentioned usability and that has a feeling of application in addition to the above-mentioned usability, thereby completing the present invention. Furthermore, it has been confirmed that the above-mentioned effects of the O/W type emulsion composition are further enhanced by blending (E) anionic thickener, (F) hydrocarbon, and/or (G) polyhydric alcohol in addition to the components (A) to (D).

The present invention has been completed based on these findings and includes the following embodiments.

(I) O/W type emulsion composition (I-1) An O/W type emulsion composition comprising the following components:
(A) ceramides,
(B) a nonionic surfactant,
(C) shea butter, and (D) water.
(I-2) The O/W emulsion composition according to (I-1), further comprising (E) an anionic thickener.
(I-3) An O/W emulsion composition according to (I-1) or (I-2), further comprising (F) a hydrocarbon.
(I-4) An O/W type emulsion composition according to any one of (I-1) to (I-3), further comprising (G) a polyhydric alcohol.
(I-5) An O/W type emulsion composition according to any one of (I-1) to (I-4), comprising 0.1 to 3% by weight of (A), 4 to 8% by weight of (B), and 0.5 to 2% by weight of (C).
(I-6) An O/W type emulsion composition according to any one of (I-1) to (I-5), which is an external preparation for skin.

(II) Method for Improving Usability/Method for Improving Application Feel (II-1) A method for improving the usability and/or application feel of an O/W type emulsion composition containing (A) ceramides, the method comprising blending (B) a nonionic surfactant, (C) shea butter, and (D) water in addition to (A) ceramides to prepare an O/W type emulsion.
(II-2) The method according to (II-1), further comprising blending (E) an anionic thickener into the O/W emulsion composition.
(II-3) The method according to (II-1) or (II-2), further comprising blending (F) a hydrocarbon into the O/W emulsion composition.
(II-4) The method according to any one of (II-1) to (II-3), further comprising blending (G) a polyhydric alcohol into the O/W emulsion composition.
(II-5) The method according to any one of (II-1) to (II-4), in which (A) is 0.1 to 3 wt %, (B) is 4 to 8 wt %, and (C) is 0.5 to 2 wt %. (II-6) The method according to any one of (II-1) to (II-5), in which the O/W emulsion composition is a skin external preparation.

The O/W emulsion composition of the present invention contains ceramides as active ingredients, yet is significantly less sticky, blends well with the skin, and has an excellent feel on the skin. Furthermore, in addition to or apart from the above-mentioned feel, the O/W emulsion composition of the present invention has a unique feel when applied (thickness) when applied to the skin. In other words, the present invention can provide an emulsion composition that has an excellent feel on the skin and/or a good feel when applied (thickness).

(I) O/W Emulsion Composition The emulsion-type pharmaceutical composition of the present invention is characterized in that it has an emulsion form and contains at least the following components:
(A) ceramides,
(B) a nonionic surfactant,
(C) shea butter, and (D) water.

Each of these components will be described below.
(A) Ceramides
The ceramides that are the subject of the present invention include ceramides (natural ceramides, human ceramides, plant ceramides, etc.) as well as ceramide analogues (pseudoceramides, etc.).

Here, ceramide is a type of sphingolipid, a general term for a group of compounds in which a long-chain fatty acid is amide-bonded to the amino group of sphingosine. They are subdivided into 11 types (ceramides 1 to 11) based on the difference in the structure of sphingosine (such as the structure of the N-acyl group) and the structure of the long-chain fatty acid (for example, Robson KJ, Stewart ME, Michelsen S, Lazo ND, Downing DT.: 6-Hydroxy-4-sphingenine in human epidermal ceramides. J Lipid Res. 1994 Nov;35(11):2060-8; and Ishida Kenya et al., "Special Feature 1: Ceramides as Functional Raw Materials and Their Applications: Development and Applications of Natural Ceramides: Optically Active Ceramide Preparations Focused on Intercellular Lipids of the Stratum Corneum," FRAGRANCE JOURNAL 2004-11:23-32).

In the present invention, any ceramide can be used as long as it has the above ceramide structure. In addition to animal- or plant-derived ceramides, ceramides obtained by organic synthesis can be used. These ceramides have asymmetric carbons and exist as optically active or racemic (optically inactive) ceramides, and either can be used in the present invention. Optically active ceramides are preferred. Of these, ceramide 1, ceramide 2, and ceramide 3 are particularly preferred. Commercially available ceramides include, for example, ceramide 1 (trade name: CERAMIDE I (manufactured by Evonik Japan Co., Ltd.)), ceramide 2 (trade name: CERAMIDE TIC-001 (manufactured by Takasago International Corporation)), and ceramide 3 (trade name: CERAMIDE III (manufactured by Evonik Japan Co., Ltd.)).

Ceramide analogues include pseudoceramides that have similar structures and properties to ceramide, and extracts and derivatives (sphingosine derivatives) from these components. Ceramide analogues include ceramide-like structural substances described in JP-A-62-228048, JP-A-63-216812, JP-A-63-227513, JP-A-64-29347, JP-A-64-31752, and JP-A-8-319263. Specific examples include compounds selected from compounds represented by the following general formula (1) and compounds represented by the following general formula (2).

［式中、Ｒ^１ｂは炭素数１０～２６の炭化水素基、Ｒ^２ｂは炭素数９～２５の炭化水素基を示し、Ｘは－（ＣＨ_２）_ｎ－を示す。なお、ｎは２～６の整数を示す。］

[In the formula, R ^1b represents a hydrocarbon group having 10 to 26 carbon atoms, R ^2b represents a hydrocarbon group having 9 to 25 carbon atoms, and X represents -(CH ₂ ) _n -. In addition, n represents an integer of 2 to 6.]

［式中、Ｒ^１及びＲ^２は同一または異なって炭素数１～４０のヒドロキシル化されていてもよい炭化水素基を示し、Ｒ^３は炭素数１～６のアルキレン基又は単結合を示し、Ｒ^４は水素原子、炭素数１～１２のアルコキシ基又は２，３－ジヒドロキシプロピルオキシ基を示す。但し、Ｒ^３が単結合であるときはＲ^４は水素原子である。］

[In the formula, ^R1 and ^R2 are the same or different and each represents a hydrocarbon group having 1 to 40 carbon atoms which may be hydroxylated, ^R3 represents an alkylene group having 1 to 6 carbon atoms or a single bond, and ^R4 represents a hydrogen atom, an alkoxy group having 1 to 12 carbon atoms or a 2,3-dihydroxypropyloxy group, provided that when ^R3 is a single bond, ^R4 is a hydrogen atom.]

In the above formulas (1) and (2), preferred examples of the hydrocarbon group include an alkyl group or an alkenyl group.

Ceramides may be used alone or in any combination of two or more. Preferred ceramides are human (optically active) ceramides, and as described above, at least one selected from the group consisting of ceramide 1, ceramide 2, and ceramide 3 is preferred. These three ceramides are preferably used in combination of two or more, preferably three. For example, when three types are used in combination, ceramide 1 can be used in a ratio of 0.002 to 300 parts by weight and ceramide 3 can be used in a ratio of 0.24 to 300 parts by weight, assuming that ceramide 2 is 100 parts by weight. The preferred ratio is 0.00495 to 100 parts by weight of ceramide 1 and 1.25 to 149.5 parts by weight of ceramide 3.

The proportion of ceramides contained in the O/W emulsion composition of the present invention is not particularly limited, so long as it is an amount that at least supplements the barrier function and moisturizing function of the stratum corneum of the epidermis and does not impair the effects of the present invention (feel when used and/or feel when applied). Usually, it can be appropriately selected in the range of 0.1 to 3% by weight per 100% by weight of the O/W emulsion composition of the present invention. It is preferably 0.2 to 3% by weight, and more preferably 0.5 to 3% by weight.

(B) Nonionic Surfactants Nonionic surfactants covered by the present invention include ether type, ester-ether type, and ester type nonionic surfactants.
Examples of the ether-type nonionic surfactants include polyoxyethylene (POE) alkyl ethers (AE) obtained by addition polymerization of ethylene oxide (EO) to higher alcohols having 10 to 18 carbon atoms; polyoxyethylene (POE) alkyl allyl ethers obtained by addition polymerization of EO to alkylphenols; and polyoxyethylene polyoxypropylene glycol obtained by addition polymerization of ethylene oxide (EO) to polypropylene glycol. Examples of the ester-ether-type nonionic surfactants include compounds in which EO is added to fatty acid esters of polyhydric alcohols, specifically polyoxyethylene sorbitan fatty acid esters. Examples of the ester-type nonionic surfactants include higher alcohol fatty acid esters such as polyglycerin, glycerin, sorbitan, sugar, and propylene glycol. These may be used alone or in any combination of two or more.

Among these, ester-type nonionic surfactants are surfactants that can be suitably used to achieve the effects of the present invention (feel when in use and/or feel when applied). Specific examples of ester-type nonionic surfactants include, but are not limited to, polyglycerin fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters.

The fatty acids constituting these ester-type nonionic surfactants are not limited, but preferably include saturated or unsaturated fatty acids having 8 to 24 carbon atoms. Examples of saturated fatty acids having 8 to 24 carbon atoms include caprylic acid (8:0), pelargonic acid (9:0), capric acid (10:0), lauric acid (12:0), myristic acid (14:0), pentadecylic acid (15:0), palmitic acid (16:0), margaric acid (17:0), stearic acid (18:0), arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0). Examples of unsaturated fatty acids having 8 to 24 carbon atoms include unsaturated fatty acids having one double bond, such as palmitoleic acid (16:1), oleic acid (18:1(9)), vaccenic acid (18:1(11)), and nervonic acid (24:1); unsaturated fatty acids having two double bonds, such as linoleic acid (18:2(9,12)) and 8,11-eicosadienoic acid (20:2(8,11)); and unsaturated fatty acids having three double bonds, such as (9,12,15)-linolenic acid (18:3), (6,9,12)-linolenic acid (18:3), and eleostearic acid (18:3(9,11,13)), and 5,8,11-eicosatrienoic acid (20:3(5,8,11)). Preferred are saturated fatty acids having 10 to 18 carbon atoms, and more preferably saturated fatty acids having 12 to 18 carbon atoms.

Among the ester-type nonionic surfactants, polyglycerol fatty acid esters and glycerol fatty acid esters are preferred.

The polyglycerol fatty acid ester is preferably an ester of polyglycerol formed by condensing 2 to 10 glycerol units and a saturated or unsaturated fatty acid having 8 to 24 carbon atoms. More preferably, it is an ester of polyglycerol formed by condensing 4 to 10 glycerol units and a saturated fatty acid having 12 to 18 carbon atoms. The glycerol fatty acid ester is preferably an ester of saturated or unsaturated fatty acid having 8 to 24 carbon atoms, more preferably an ester of saturated fatty acid having 12 to 18 carbon atoms.

Specific examples of these polyglycerol fatty acid esters include polyglyceryl-6 laurate, polyglyceryl-6 myristate, polyglyceryl-6 stearate, polyglyceryl-10 laurate, polyglyceryl-10 myristate, and polyglyceryl-10 stearate, and specific examples of glycerol fatty acid esters include glyceryl myristate, glyceryl stearate, and glyceryl oleate.

The proportion of the nonionic surfactant contained in the O/W emulsion composition of the present invention is not particularly limited as long as it is an amount that exerts the effects of the present invention. Usually, it can be appropriately selected in the range of 4 to 8% by weight per 100% by weight of the O/W emulsion composition. Examples of preferred amounts include 5 to 8% by weight, and more preferably 5.5 to 8% by weight.

(C) Shea butter Shea butter is a vegetable fat obtained from the seed embryo of the Butterbur tree of the Sapotaceae family, and is composed mainly of stearic acid and oleic acid. It is also called shea butter.

The proportion of shea butter contained in the O/W emulsion composition of the present invention is not particularly limited as long as it is an amount that exhibits the effects of the present invention. Usually, it can be appropriately selected in the range of 0.5 to 2% by weight per 100% by weight of the O/W emulsion composition. Preferably, it can be 0.75 to 2% by weight, more preferably 1 to 2% by weight.

(D) Water The type of water is not particularly limited, and for example, purified water, distilled water, ionized water, sterilized water, deep sea water, etc. can be used without limitation. Purified water is preferred. The blending ratio of the water in the O/W emulsion composition of the present invention can be appropriately set usually within the range of 20 to 95.4% by weight. It is preferably 25 to 90% by weight, and more preferably 30 to 90% by weight.

The O/W emulsion composition of the present invention may contain at least the above-mentioned components (A) to (D), but may also contain at least one selected from the group consisting of the following (E) anionic thickener, (F) hydrocarbon, and (G) polyhydric alcohol. These components are described below.

(E) Anionic Thickener The O/W emulsion composition of the present invention may further contain (E) an anionic thickener, in addition to the above-mentioned components (A) to (D).

Examples of anionic thickeners include, but are not limited to, polymeric thickeners such as carboxymethylcellulose, hyaluronic acid, alginic acid, xanthan gum, carrageenan, gum arabic, guar gum, carboxyvinyl polymer, acrylic acid/alkyl methacrylate copolymer, and sodium polyacrylate.

These anionic thickeners may be of natural or synthetic origin, and there are no particular limitations on their origin. They may be used alone or in any combination of two or more. Carboxyvinyl polymers, acrylic acid/alkyl methacrylate copolymers, and xanthan gum are preferred.

In order to more effectively achieve the effects of the present invention, two or more types of anionic thickeners can be used in combination. Although not particularly limited, such combinations include a combination of a carboxyvinyl polymer, an acrylic acid/alkyl methacrylate polymer, and xanthan gum, a combination of a carboxyvinyl polymer and an acrylic acid/alkyl methacrylate copolymer, a combination of a carboxyvinyl polymer and xanthan gum, and a combination of an acrylic acid/alkyl methacrylate copolymer and xanthan gum. A combination of a carboxyvinyl polymer and an acrylic acid/alkyl methacrylate copolymer and xanthan gum is preferred.

The blending ratio of the anionic thickener in the O/W emulsion composition of the present invention (total amount when two or more types are used in combination) can be appropriately set usually within the range of 0.025 to 1 wt% per 100 wt% of the O/W emulsion composition. It is preferably 0.05 to 1 wt%, and more preferably 0.05 to 0.5 wt%.

The O/W emulsion composition of the present invention may further contain a hydrocarbon (F) in addition to the above-mentioned components (A) to (D) or components (A) to (E). As shown in the experimental examples described later, by blending component (F) in addition to components (A) to (D), particularly components (A) to (E), it is possible to prepare an O/W emulsion composition that reduces the sticky feeling during use and provides a sense of thickness when applied.

The hydrocarbon is not particularly limited as long as it does not impair the effects of the present invention and is a component that can be used in compositions for external use, particularly in the field of cosmetics, for example. In general, however, those having a molecular weight of 200 to 1,000,000 are preferred, and among these, those that are liquid at room temperature (25° C.) are preferred. Examples include hydrogenated polyisobutene, α-olefin oligomer, vegetable squalane, squalane, liquid paraffin, pristane, mineral oil, and petrolatum. These may be used alone or in any combination of two or more. Among these hydrocarbons, squalane, vegetable squalane, liquid paraffin, and mineral oil are preferred, as they are more likely to provide the effects of the present invention, and squalane and vegetable squalane are more preferred.

The blending ratio of the hydrocarbon in the O/W emulsion composition of the present invention can be set appropriately within the range of usually 1 to 30% by weight. It is preferably 2.5 to 30% by weight, and more preferably 5 to 25% by weight.

(G) Polyhydric Alcohol The O/W emulsion composition of the present invention may further contain (G) a polyhydric alcohol in addition to the above-mentioned components (A) to (D), (A) to (E), or (A) to (F). As shown in the experimental examples described later, by blending component (G) in addition to components (A) to (D), (A) to (E), and particularly components (A) to (F), an O/W emulsion composition having excellent usability (non-sticky, compatible with skin) can be prepared.

The polyhydric alcohol may be any component that does not impair the effects of the present invention and can be used in compositions for external use, particularly in the field of cosmetics, and is not particularly limited. For example, a polyhydric alcohol having 2 to 6 carbon atoms and 2 to 4 hydroxyl groups can be used. Specific examples include dihydric alcohols such as ethylene glycol, propylene glycol, 1,3-propanediol (trimethylene glycol), 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butanediol (tetramethylene glycol), 2-butene-1,4-diol, 1,5-pentanediol (pentamethylene glycol), 1,2-pentanediol, isoprene glycol (isopentyl diol), hexylene glycol, diethylene glycol, and dipropylene glycol, and pentylene glycol; trihydric alcohols such as glycerin (including concentrated glycerin) and trimethylolpropane; and tetrahydric alcohols such as diglycerin, pentaerythritol, and 1,2,6-hexanetriol.

Of these, from the viewpoint of more effectively exerting the effects of the present invention, 1,3-butylene glycol, 1,2-pentanediol, dipropylene glycol, propylene glycol and glycerin are preferred, and 1,3-butylene glycol and glycerin are more preferred.

The blending ratio of the polyhydric alcohol in the O/W emulsion composition of the present invention can be appropriately set within the range of 0.1 to 10% by weight per 100% by weight of the O/W emulsion composition. It is preferably 0.1 to 5% by weight, and more preferably 0.1 to 3% by weight.

(H) Other components (optional components) to be incorporated in the O/W emulsion composition
In the O/W emulsion composition of the present invention, other components can be appropriately selected and blended in one or more combinations depending on the form, etc., so long as the effects of the present invention are not impaired. Examples of functional components include skin absorption enhancers (skin penetration enhancers), whitening agents, moisturizing agents, anti-inflammatory agents, anti-wrinkle agents, blood circulation enhancers, and local anesthetics.
Specifically, the following can be mentioned:

(H-1) As the skin absorption enhancer (skin penetration enhancer), those having the effect of enhancing the percutaneous permeability of ceramides and promoting their absorption into the skin can be used. Examples of such enhancers include, without limitation, fatty acids and fatty acid esters (oleic acid, isopropyl myristate, medium-chain fatty acid triglycerides, etc.), biodegradation enhancers (alkyl esters, aminocaproic acid), as well as amino acids, terpenes, pyrrolidones, urea, phospholipids, and various solvents (polyols, lower alcohols, higher alcohols, dimethylfursulfoxide, etc.).

(H-2) Whitening agents include arbutin, vitamin C, vitamin C derivatives, cysteine,
and tranexamic acid, etc., can be exemplified without limitation.
Examples of (H-3) anti-inflammatory agents include, without limitation, loxoprofen sodium, indomethacin, flurbiprofen sodium, chlorpheniramine maleate, glycyrrhetinic acid, and dipotassium glycyrrhizinate.
(H-4) Anti-wrinkle agents include, without limitation, hyaluronic acid, collagen, retinol, heparinoids, urea, and the like.
(H-5) Examples of blood circulation promoters include, without limitation, vitamin E, ginger tincture, sage extract, mugwort extract, placenta, and the like.
(H-6) Examples of local anesthetics include, without limitation, lidocaine, dibucaine, bupivacaine, and the like.

Further, optional components that can be blended in the O/W emulsion composition of the present invention include various additives that are generally used in the preparation of emulsion preparations, such as oily components, stabilizers, preservatives, buffers, and pH adjusters.
(H-7) Examples of oily components include higher alcohols, vegetable oils, and plant sterols (such as phytosterols).

Examples of higher alcohols include aliphatic alcohols having 6 or more carbon atoms, more preferably 6 to 30 carbon atoms. The oil component is preferably solid at room temperature (25°C). Specific examples include cetanol, behenyl alcohol, myristyl alcohol, cetyl alcohol, oleyl alcohol, stearyl alcohol, isostearyl alcohol, hexadecyl alcohol, and lanolin alcohol. These higher alcohols may be used alone or in combination of two or more.

Examples of vegetable oils include macadamia seed oil, jojoba seed oil, canina rose fruit oil, coconut oil, avocado oil, olive oil, apricot kernel oil, kukui nut oil, grape seed oil, safflower oil, sweet almond oil, corn germ oil, sunflower oil, hazelnut oil, jojoba wax, and rosehip oil. These vegetable oils may be used alone or in combination of two or more.

Plant sterols (phytosterols) are present in the cell membranes of plants and are a mixture of sitosterol, which has a double bond, as well as stigmasterol, campesterol, brassicasterol, fucosterol, and sterols which do not have a double bond. The plant sterols used in the present invention are not particularly limited, and examples thereof include extracts and refined products from grains such as soybeans, rice, wheat, and sesame; fruits and vegetables such as radish, cabbage, apples, and lettuce; and other plants such as sunflowers, rapeseed, palm, cotton, and tree bark. The type of plant raw material to be extracted is not particularly limited, but preferred examples include plant sterols obtained by separating from scum produced during the deodorization process of vegetable oils, and sterols obtained as by-products during pulp production.

Examples of (H-8) pH adjusters include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, and boric acid; organic acids such as lactic acid, acetic acid, citric acid, tartaric acid, malic acid, succinic acid, oxalic acid, gluconic acid, fumaric acid, propionic acid, acetic acid, aspartic acid, epsilon-aminocaproic acid, glutamic acid, and aminoethylsulfonic acid; inorganic bases such as sodium bicarbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, and magnesium hydroxide; and organic salts such as monoethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, and lysine.

(H-9) Examples of preservatives include butylparaben, methylparaben, propylparaben,
Examples include ethylparaben, sodium benzoate, phenol and benzyl alcohol.

(H-10) Examples of stabilizers include dibutylhydroxytoluene, sodium edetate, sodium sulfite, and dry sodium sulfite.

(H-11) Examples of buffers include borate buffers, phosphate buffers, carbonate buffers, citrate buffers, acetate buffers, epsilon-aminocaproic acid, aspartic acid, and aspartate salts.

(H-12) Other ingredients include sodium carboxymethyl starch, magnesium stearate, cellulose, lactose, hard fat, D-sorbitol, medium-chain fatty acid triglyceride, corn starch, etc.

(I) Method for preparing and using the O/W emulsion composition The O/W emulsion composition of the present invention can be prepared by a known method, for example, by mixing the above components (A) to (D) and, if necessary, at least one of the components described in (E) to (H), heating the mixture to a temperature of about 75 to 85° C., and then emulsifying the mixture under predetermined conditions using a mixer such as a homogenizer, a homomixer, or a stirrer.

Here, the hardness of the O/W emulsion composition of the present invention is not particularly limited, but is usually adjusted to 15 to 120 g, preferably 20 to 100 g, and more preferably 30 to 80 g. The hardness is measured by the following method using a rheometer "Model: CR-500DX (Sun Scientific, adapter diameter 20 mm, circular)".

(Method)
40 g of a sample (emulsion composition) is placed in a circular jar with a diameter of about 4 cm and a height of 3 cm, and measured at room temperature (about 25° C.) (constant depth measurement, measurement speed 38 mm/min). The maximum load (g) during measurement is taken as the measured value (measurement count is 1).

The O/W emulsion composition of the present invention is a liquid to semi-solid oil-in-water emulsion composition, which can be suitably used as a skin topical agent. Specific examples of the form of the skin topical agent include semi-solid ointments and creams. Thus, the emulsion composition of the present invention is in a semi-solid state, is easy to take in the hands when used, has good spreadability, is less sticky, is easily absorbed into the skin, and has an excellent feel when used. Furthermore, it has a shape-retaining feel when applied, and while the user feels the sensation of it being rubbed into the skin, it also has an excellent feel when applied (thickness) that gradually absorbs into the skin.

The O/W emulsion composition of the present invention can be prepared in any of the following forms: topical medicine, topical quasi-drug, and cosmetic, depending on the purpose. The form of the cosmetic is not particularly limited, and may be, for example, massage cream, moisture cream, lip cream, etc. as skin care cosmetics; foundation, lipstick, blusher, eye shadow, etc. as makeup cosmetics. Various cosmetic ingredients generally used in cosmetics may be appropriately blended into the above-mentioned cosmetics.

The O/W emulsion composition is usually applied to the target skin once to multiple times a day as needed. In this case, the amount of ceramide contained in one application of the O/W emulsion composition is not limited, but can be, for example, about 1 to 30 mg/g.

(II) Method for Improving Usability/Method for Improving Application Feel The present invention provides a method for improving the usability of an O/W emulsion composition containing (A) ceramides. The present invention also provides a method for improving the application feel of an O/W emulsion composition containing (A) ceramides. The usability here can include non-stickiness when used on the skin and/or a feeling of compatibility with the skin. The application feel can include a feeling of thickness. The details are as explained in (I), and the description therein can be incorporated by reference herein.

This method can be carried out by further blending (B) a nonionic surfactant, (C) shea butter, and (D) water in addition to the above-mentioned (A) component when preparing the O/W emulsion composition. In addition to these components, the composition further contains at least one selected from the group consisting of (E) an anionic thickener, (F) a hydrocarbon, and (G) a polyhydric alcohol.

The types and blending ratios of (A) ceramides, (B) nonionic surfactants, (C) shea butter, (D) water, (E) anionic thickeners, (F) hydrocarbons, and (G) polyhydric alcohols used in the method of the present invention are as described in (I) above. Therefore, the descriptions of (A), (B), (C), (D), (E), (F), and (G) in (I) above can be used in the present invention.

In the method for improving the usability/application feel of an O/W emulsion composition of the present invention, the method for preparing the target emulsion composition is also as described in (I) above. Therefore, the description in (I) above can be used in the present invention.

According to the method for improving usability of the present invention, it is possible to suppress stickiness when an O/W emulsion composition containing ceramides is applied to the skin and improve compatibility with the skin, as shown in the experimental examples described later. According to the method for improving application feel of the present invention, it is possible to impart and improve the feel (thickness) of an O/W emulsion composition containing ceramides when applied to the skin, as shown in the experimental examples described later.

The present invention will be specifically explained below based on experimental examples and examples. However, the present invention is not limited to these in any way.

Experimental Example 1 Preparation and Evaluation of O/W Emulsion Composition
(1) Preparation of test samples O/W type emulsion compositions (Examples 1 to 6, Comparative Example 1) were prepared having the compositions shown in Table 1. Specifically, the aqueous phase (purified water, anionic thickener [acrylic acid/alkyl methacrylate copolymer, carboxyvinyl polymer, xanthan gum], pH adjuster) and oil phase (components other than the aqueous phase components) prepared respectively were mixed and stirred until an emulsified state was obtained, to prepare each O/W type emulsion composition (Examples 1 to 6, Comparative Example 1, all pH 7).

(2) Test method Five panelists specializing in cosmetic evaluation applied each of the O/W emulsion compositions prepared above to the back of the hand under the following test conditions, and evaluated the feel in use (skin compatibility, sticky feeling) and feel on application (thickness) according to the following criteria. For each of Examples 1 to 6 and Comparative Example 1, the scores of the five panelists were totaled for each evaluation item. In addition, the total scores of these evaluation items (skin compatibility, sticky feeling, thick feeling) were added up for each Example (and Comparative Example 1) to obtain an overall evaluation of each O/W emulsion composition.

(a) Test conditions Application environment: temperature 25°C, relative humidity 40-50%
Application method: 0.2 g of the O/W emulsion composition was placed on the back of the hand, and the pad of the index finger of the opposite hand was used to rub the composition into a 2 x 2 cm area in a circular motion.

(b) Evaluation criteria : Skin compatibility
The sensation of the emulsion composition being absorbed into the skin as it is spread with the fingers from the back of the hand is evaluated on a 5-point scale. The highest rating is 5, and the lowest rating is 1, with the evaluation being done in increments of 1 (the same goes for the "sticky feeling" and "thickness" below). Specifically, when the sensation is strong, it is evaluated as "5: good", and as the degree of the sensation weakens, it is evaluated as "4: slightly good", "3: neither good nor bad", "2: slightly bad", and "1: bad". Note that "bad" means that "the composition remains on the skin even after spreading, and it takes a long time to finish applying, so the sensation of absorption into the skin is felt to be bad".

<Sticky feeling>
The sticky feeling felt on the application site on the back of the hand after applying the emulsion composition was evaluated on a 5-point scale. Specifically, when there was no or almost no sticky feeling, it was rated as "5: good", and as the sticky feeling increased, it was rated as "4: slightly good", "3: neither good nor bad", "2: slightly bad", and "1: bad".

<Thickness>
"Shape retention of the emulsion composition placed on the back of the hand,""feel when spreading," and "feel of application on the skin after application" were each evaluated on a 5-point scale based on the following criteria.

The total score for each evaluation item and the overall evaluation was judged according to the following criteria.

(3) Test Results The results are shown in Table 4.

As can be seen from these results, by blending (C) shea butter into an O/W type emulsion composition (Comparative Example 1) containing (A) ceramide, (B) nonionic surfactant, and (D) water (Example 4), the feeling of use (stickiness, skin compatibility) was significantly improved, and a feeling of thickness was felt upon application. Furthermore, by blending (F) hydrocarbon therein (Examples 2 and 3), the feeling of use and the feeling of thickness were increased, and this effect was enhanced by increasing the amount of (F) hydrocarbon. Furthermore, by blending polyhydric alcohol therein (Examples 1, 5, and 6), the feeling of use (non-stickiness, skin compatibility) was improved.
Examples 7 to 12
According to the formulations shown in Tables 5 and 6, O/W emulsion compositions of the present invention (Examples 7 to 12, pH of Example 11 was 7) were prepared in the same manner as in Experimental Example 1.

Claims (1)

An O/W type emulsion composition comprising the following components:
(A) 0.25 to 3% by weight of at least one ceramide selected from the group consisting of ceramide 1, ceramide 2, and ceramide 3;
(B) 5.5 to 8% by weight of an ester-type nonionic surfactant,
(C) 0.5 to 2% by weight of shea butter,
(F) 5 to 25 weight percent of a hydrocarbon; and (D) water .