External skin care preparation

Abstract: An external skin care preparation comprising a compound represented by the following general formula (II), or a salt thereof: General formula (II) : wherein R⁶ and R⁷ mean individually an aliphatic hydrocarbon group having 10-26 carbon atoms and R⁸ denotes a group -CH₂CH₂OH, -CH₂COOH or -COCH₃ , and further comprising a surfactant.

Description: BACKGROUND OF THE INVENTION 1) Field of the Invention : This invention relates to an external skin care preparation, and more specifically to an external skin care preparation which can enhance the water-retaining ability of the horny layer and improve skin roughness. 2) Description of the Related Art : The water content of the horny layer has already been known to be critical for imparting moisture to the skin to maintain the skin smoothness and softness. The retention of water is said to rely upon a water-soluble component contained in the horny layer, namely, a free amino acid, organic acid, urea or inorganic ions. These materials have been incorporated either singly or in combination in medical external skin care preparations or cosmetic preparations with a view toward improving or avoiding skin roughness. Besides, many humectants having high affinity with water have also been developed and have been used for similar purposes. However, these humectants remain on the skin surface when they are applied to the skin, so that they serve to supply water to horny layer. Moreover, their effects are temporary and they are not such that can improve the water-retaining ability of the horny layer and can also avoid or cure skin roughness substantially. SUMMARY OF THE INVENTION Under the above circumstances, the present inventors have carried out an extensive investigation with a view toward solving the above problems. As a result, it has been found that a compound represented by the following general formula (II) or a salt thereof shows effects in improving the water-retaining ability of the horny layer significantly and the combined use of a surfactant with the compound or salt can enhance the effects further, leading to completion of this invention. wherein R⁶ and R⁷ mean individually an aliphatic hydrocarbon group having 10-26 carbon atoms and R⁸ denotes a group -CH₂CH₂OH, -CH₂COOH or -COCH₃. In one aspect of the invention, there is thus provided an external skin care preparation comprising a compound represented by the formula (II) or a salt thereof, and additionally containing a surfactant. Although details of the mechanism of action of the compound represented by the formula (II) or a salt thereof in the external skin care preparation of this invention has not been elucidated fully, it appears to reconstruct lipid membranes between horny cells to allow the horny layer to exhibit its water-retaining function. Owing to the inclusion of the compound (II) or a salt thereof having such an action, the external skin care preparation according to the present invention can exhibit excellent effects for the improvement and prevention of skin roughness. The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims. DETAILED DESCRIPTION OF THE INVENTION The compounds of the formula (II) useful in the practice of this invention have already been known. Those represented by the formula (II) in which R⁸ is a group -CH₂CH₂OH or -COCH₃ can be prepared, for example, by the process described in Polish. J. Chem., 52 , 1059(1978) referred to above. On the other hand, the compound of the formula (II) in which R⁸ is a group -CH₂COOH can be prepared, for example, in accordance with the process of East German Patent No. 92940 (1973). As illustrative examples of the salt of the compound (II) useful in the practice of this invention, may be mentioned those usable in cosmetic compositions, such as alkali metal salts. No particular limitation is imposed on the proportion of the compound represented by the formula (II) or a salt thereof in the external skin care preparation. In the case of an emulsion-type external skin care preparation, its proportion may preferably be 0.001-50 wt.% (hereinafter indicated merely by "%"), notably, 0.1-20% of the whole preparation. In the case of an oil-base external skin care preparation containing a liquid hydrocarbon such as squalene as a base, its proportion may preferably be 1-50%, notably, 5-25%. As a surfactant suitable for incorporation in the external skin care preparation, any one of non-ionic surfactants, anionic surfactants and amphoteric surfactants may be mentioned. Of these, non-ionic surfactants are especially suitable. As exemplary non-ionic surfactants, may be mentioned polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, glyceryl ethers, etc. Among these, glyceryl ethers represented by the following general formula (VII): wherein R means an alkyl group having 8 - 24 carbon atoms are preferred. Particularly preferred are glyceryl ethers of the formula (VII) in which R is represented by the following formula (VIII): wherein p means an integer of 4 - 10, q denotes an integer of 5 - 11, and p + q is 11 - 17 and is distributed with a peak at p = 7 and q = 8. The proportion of the surfactant may be 0.01 - 20% of the whole preparation, with 0.1 - 5% being particularly preferred. External skin care preparations according to this invention may be classified roughly into medicinal external skin care preparation and cosmetic preparations in accordance with their manner of use. As exemplary medicinal external skin care preparations, may be mentioned various ointments containing one or more medicinally-effective ingredients. Ointments include both those containing an oily base as a base and those containing an oil/water or water/oil emulsion-type base as a base. No particular limitation is imposed on oily bases. Plant oils, animal oils, synthetic oils, fatty acids, natural and synthetic glycerides, etc. may be mentioned by way of example. No specific limitation is imposed on medicinally-effective ingredients. For example, one or more of analgesic and antiphlogistic agents, antipruritics, disinfectants, astringents, emollients, hormones and the like may be used suitably as needed. Where used as a cosmetic preparation, it is possible to mix in addition to the essential ingredients those employed routinely as cosmetic ingredients such as oily substance, moisturizer, ultraviolet absorbent, alcohol, chelating agent, pH regulator, antiseptic, thickener, pigment, perfume base and the like in combination as needed. As cosmetics, skin cosmetic preparations of various forms may be formulated including, for example, water/oil or oil/water type emulsified cosmetics, creams, cosmetic emulsions, toilet waters, oily cosmetics, lip sticks, foundations, skin cleansing preparations, hair tonics, hair styling preparations, hair grooming preparations, hair growth stimulants, etc. Having generally described the invention, a more complete understanding can be obtained by reference to certain specific examples, which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. Examples: The present invention will hereinafter be described by the following Referential Examples and Examples. Example 1: (Reference) Conventional compounds II₁-II₂ were used separately. Mixtures, each of which had been formulated by mixing vaseline and the compound (II) at a weight ratio of 3:1, and vaseline (Comparative Product 1) were evaluated in skin conductance and skin roughness by the following methods. Results will be summarized in Table 1. (Testing methods) Chosen as volunteers in winter were 10 women of 20 - 50 years of old who had skin roughness on their both cheeks. Different external skin care preparations were coated separately on the left and right cheeks of each volunteer for two weeks. On the following day of the the completion of the two-week coating test, tests were conducted with respect to the following properties. (1) Skin conductance: After washing the face with warm water of 37°C, each volunteer was allowed to rest for 20 minutes in a room which was air-conditioned at 20°C and 40% humidity. The water content of her horny layer was measured by a skin conductance meter (manufactured by IBS Company). A smaller conductance value indicates greater skin roughness. Conductance values of 5 and smaller indicate severe skin roughness. On the contrary, no substantial skin roughness is observed where this value is 20 or greater. (2) Score of skin roughness: Skin roughness was observed visually and ranked in accordance with the following standard. Each score was indicated by an average value. Score Ranking of skin roughness 0 No skin roughness was observed. 1 Slight skin roughness was observed. 2 Skin roughness was observed. 3 Rather severe skin roughness was observed. 4 Severe skin roughness was observed. Example 2: Using separately the compounds used in Example 1, external skin care preparations (emulsified cosmetic preparations) of their corresponding compositions shown below in Table 2 were formulated. Their effects for the improvement of skin roughness were evaluated in the same manner as in Example 1. Results are shown in Table 3. Example 3: Cosmetic Emulsion A cosmetic emulsion was formulated in accordance with the below-described composition. The water-phase components were maintained at 70°C while mixing them under heat. On the side, the oil-phase components were heated and mixed at 80°C. After adding the above-mentioned water-phase components gradually under stirring to the oil-phase components, the resultant mixture was emulsified uniformly by a homomixer. Subsequent to the emulsification, the mixture was cooled down to 30°C by a heat exchanger to obtain the cosmetic emulsion. Oil-phase components: (wt.%) Compound II₁ 1.0 Microcrystalline wax 0.5 Bees wax 2.0 Lanolin 1.5 Liquid paraffin 30.0 Sorbitan sesquioleate 4.0 Polyoxyethylenesorbitan monooleate (20 E.O.) 1.0 Aluminum stearate 0.2 Butyl paraben 0.1 Water-phase components: Glycerin 8.0 Methyl paraben 0.3 Perfume base 0.1 Purified water Balance Example 4: Cleansing Cream A cleansing creams was formulated in accordance with the below-described composition. The oil-phase components were maintained at 80°C while mixing them under heat. The water-phase components which had been heated and mixed at 70°C on the side were added to the above-mentioned oil-phase components, and the resultant mixture was then emulsified uniformly by a homogenizer. Subsequent to the emulsification, the mixture was cooled down to 30°C by a heat exchanger to obtain the cleansing cream. Oil-phase components: (wt.%) Compound II₁ 3.0 Paraffin 2.0 Cetanol 1.0 Vaseline 18.5 Liquid paraffin 28.0 Glycerin monostearate polyoxyethylene monolaurate (20 E.O.) 3.0 Water-phase components: Propylene glycol 3.0 Glycerin 2.0 Methyl paraben 0.3 Perfume base 0.1 Purified water Balance Example 5: Toilet Water A toilet water was formulated in accordance with the below-described composition. Glycerin and propylene glycol were added to purified water. The former components were dissolved in the latter at room temperature to obtain a purified water portion. On the other hand, emollient and the surfactant, antiseptic and perfume base were added to ethanol, and the former components were dissolved in the latter at room temperature. The thus-formed solution was added to the above-mentioned purified water portion to solubilize the former. The resultant solution was modified in color with a dye and then filtered to obtain the toilet water. (wt.%) Moisturizers: Glycerin 5.0 Propylene glycol 4.0 Emollient: Compound II₂ 0.1 Surfactant: Polyoxyethylene hydrogenated castor oil (40 E.O.) 1.0 Ethanol 10.0 Antiseptic: Methyl paraben 0.2 Purified water Balance Example 6: Lip Stick A lip stick was prepared in accordance with the below-described composition. Base materials were heated and molten, and were then mixed uniformly. A color was added to the melt. After kneading the resultant mixture and dispersing the color evenly, the mixture was molten again and a perfume base was added. The melt was defoamed and poured into a mold. The mold was cooled quickly to solidify the melt. The thus-solidified stick was taken out of the mold and filled in a dispenser. After straightening up the external appearance of the stick further, it was caused to pass through a flame (flaming) whereby its surface was rendered uniform to obtain the lip stick. Base materials: (wt.%) Compound II₃ 5.0 Castor oil 45.0 Hexadecyl alcohol 23.0 Lanolin 4.0 Bees wax 5.0 Ozocerite 4.0 Candelilla wax 4.0 Carnauba wax 2.0 Tocopherol 0.1 Butyl paraben 0.1 Colors: Titanium oxide 2.0 Red Color No. 202 0.5 Red Color No. 204 2.5 Red Color No. 227 (Al rake) 2.5 Orange Color No. 201 0.2 Perfume base 0.1 Example 7: Emulsion-Type Foundation An emulsion-type foundation was formulated in accordance with the below-described composition. The oil-phase components were mixed, heated and molten, and maintained at 80°C. On the other hand, the powdery components were added to and dispersed in the water-phase components. The resultant dispersion was heated to 70°C. The above oil-phase components were added to the water-phase components, followed by emulsification and dispersion by an emulsifying machine. An emulsion thus obtained was cooled down to 30°C by a heat exchanger to obtain the emulsion-type foundation. Oil-phase components: (wt.%) Compound II₄ 3.0 Stearic acid 5.0 Cetostearyl alcohol 1.0 Jojoba oil 15.0 Glycerin monostearate 2.0 Propylene glycol monolaurate 3.0 Water-phase components: Propylene glycol 4.0 Triethanolamine 1.2 Methyl paraben 0.3 Perfume base 0.1 Purified water Balance Powdery components: Titanium oxide 8.0 Talc 4.0 Iron oxide 0.5 Example 8: Hair Tonic A hair tonic was formulated in accordance with the below-described composition. (wt.%) Compound II₂ 0.2 Menthol 0.2 Pilocton auramine (antidandruff agent) 0.1 Methyl nicotinate 0.1 Ethanol 50.0 Purified water Balance Example 9: A cosmetic emulsion was obtained in the same manner as in Example 3 except that Compound II₉ was used in place of Compound II₁. Example 10: A cleansing cream was obtained in the same manner as in Example 4 except that Compound II₉ was used instead of Compound II₁. Example 11: A toilet water was obtained in the same manner as in Example 5 except that Compound II₁₀ was used in lieu of Compound II₂. Example 12: A lip stick was obtained in the same manner as in Example 6 except that Compound II₁₁ was used in lieu of Compound II₃. Example 13: An emulsion-type foundation was obtained in the same manner as in Example 7 except that Compound II₁₂ was used instead of Compound II₄. Example 14: A hair tonic was obtained in the same manner as in Example 8 except that Compound II₁₀ was used in lieu of Compound II₂. Example 15: Cosmetic Emulsion In accordance with the below-described composition, the oil-phase components were mixed, heated and molten, and maintained at 70°C. The water-phase components were also mixed, heated and molten at 70°C. The above oil-phase components were added to the water-phase components, followed by emulsification by an emulsifying machine. An emulsion thus obtained was cooled down to a final temperature of 30°C by a heat exchanger to obtain a cosmetic emulsion. Oil-phase components: (wt.%) Cetanol 0.5 Vaseline 3.0 Compound II₅ 5.0 Polyoxyethylene (10) monooleate 2.0 Stearic acid 2.0 Water-phase components: 1,3-Butylene glycol 3.0 Dipropylene glycol 6.0 Triethanolamine 1.0 Ethyl paraben 0.1 Methyl paraben 0.2 Perfume base 0.1 Purified water Balance Example 16: Emulsion-Type Foundation In accordance with the below-described composition, the oil-phase components were mixed, heated and molten, and maintained at 70°C. On the other hand, the powdery components were added to and dispersed in the water-phase components. The resultant dispersion was heated to 70°C. The above oil-phase components were added to the water-phase components, followed by emulsification and dispersion by an emulsifying machine. An emulsion thus obtained was cooled down to a final temperature of 30°C by a heat exchanger and was then filled in a container, whereby the emulsion-type foundation was obtained. Oil-phase components: (wt.%) Stearic acid 5.0 Cetostearyl alcohol 1.0 Olive oil 15.0 Compound II₅ 3.0 Glycerin monostearate 2.0 Propylene glycol monolaurate 3.0 Water-phase components: Propylene glycol 4.0 Triethanolamine 1.2 Ethyl paraben 0.1 Methyl paraben 0.2 Perfume base 0.1 Purified water Balance Powdery components: Titanium oxide 8.0 Talc 4.0 Iron oxide 0.5 Example 17: Lip Stick In accordance with the below-described composition, a lip stick was obtained by heating and melting microcrystalline wax, candelilla wax, castor oil, Compound II₅, jojoba oil, olive oil and lanolin at 90-100°C, adding the pigment to the melt, stirring the resultant mixture to disperse the pigment, deaerating the the thus-pigmented mixture, adding the perfume base to the thus-deaerated mixture, pouring it into a stick mold, cooling the mold to 15-20°C and then taking the resultant lip stick out of the mold. (wt.%) Microcrystalline wax 6.0 Candelilla wax 3.0 Castor oil 40.0 Compound II₅ 8.0 Jojoba oil 6.0 Lanolin 10.0 Olive oil Balance Pigment 7.0 Perfume base 0.1 Example 18: W/O Type Massage Cream In accordance with the below-described composition, soap powder was added to purified water, and the resultant mixture was heated to and maintained at 70°C. The oil-phase components were mixed, and then heated to and maintained at 70°C. The above water-phase portion was added to the oil-phase portion, followed by provisional emulsification. The resultant mixture was thereafter emulsified evenly by a homomixer, followed by cooling to room temperature or so by a heat exchanger. Oil-phase components: (wt.%) Paraffin 4.0 Microcrystalline wax 6.0 Bees wax 6.0 Vaseline 10.0 Compound II₈ 4.0 Liquid paraffin 40.0 Sorbitan sesquioleate 3.5 Polyoxyethylene sorbitan monooleate (20 E.O.) 0.5 Water-phase components: Ethyl paraben 0.1 Methyl paraben 0.2 Tocopheryl acetate 0.5 Soap powder 0.3 Purified water Balance Example 19: Pack (Peel-Off Type) In accordance with the below-described composition, the water-phase components were mixed, heated and molten, and maintained at 70°C. Similarly, the oil-phase components were heated to and mixed at 70°C. The oil-phase components were added to the above water-phase components, and the resultant mixture was emulsified by an emulsifying machine. The powdery components and film-forming agent were added to and mixed with the emulsion. The resultant emulsion was cooled down to a final temperature of 30°C by a heat exchanger and then filled in a container, whereby a pack was obtained. Oil-phase components: (wt.%) Squalane 2.0 Compound II₆ 1.0 Hydrophobic glycerin monostearate polyoxyethylene 1.0 sorbitan monolaurate (20 E.O.) Water-phase components: Glycerin 3.0 Propylene glycol 3.0 Veegum 1.0 Purified water Balance Ethanol 7.0 Powdery components: Titanium oxide 10.0 Kaolin 3.0 Film-forming agent: Polyvinyl alcohol 10.0 Perfume base 0.5 Antiseptic 0.1 Example 20: Hair Tonic The following components were heated to and dissolved at 70°C, and were then cooled to obtain a hair tonic. (w.t%) Compound II₇ 0.2 Menthol 0.2 Pilocton auramine (antidandruff agent) 0.1 Methyl nicotinate 0.1 Ethanol 45.0 Purified water Balance All the external skin care preparations obtained in Examples 3-20 were highly effective for the improvement of skin roughness and exhibited superb moistening ability.

Claims: An external skin care preparation comprising a compound represented by the following general formula (II), or a salt thereof: wherein R⁶ and R⁷ mean individually an aliphatic hydrocarbon group having 10-26 carbon atoms and R⁸ denotes a group -CH₂CH₂OH, -CH₂COOH or -COCH₃, and further comprising a surfactant.

Inventors: AKAZAKI SHUICHI, IMOKAWA GENJI, KAWAMATA AKIRA, KOMORI TAKASHI, MINEMATSU YOSHIHIRO, OHTOMO TSUYOSHI, TAKAISHI NAOTAKE, YANO SHINJI, ZAMA MITSUKO, AKAZAKI, SHUICHI, IMOKAWA, GENJI, KAWAMATA, AKIRA, KOMORI, TAKASHI, MINEMATSU, YOSHIHIRO, OHTOMO, TSUYOSHI, TAKAISHI, NAOTAKE, YANO, SHINJI, ZAMA, MITSUKO
Applicants: KAO CORP, KAO CORPORATION
Application year: 1988
Main classification: A61K7
IPC codes: A61K8, A61Q19, A61Q5