Cosmetic composition

Abstract

To provide means that enables stable incorporation of cholesterol into an oil-based component.SOLUTION: A cosmetic composition contains (a) cholesterol, (b) isostearic acid, and (c) liquid oil with a viscosity of 50 mPa s or less at 25°C, where the mass ratio between the component (a) and the component (b) (a / b) is in the range of 1 / 8-1 / 20, and the mass ratio between the component (b) and the component (c) (b / c) is in the range of 10 / 1-1 / 1.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a cosmetic composition containing cholesterol. [Background technology]

[0002] Cholesterol is one of the components that form the lamellar structure in the stratum corneum of the epidermis, and plays an important role in maintaining the barrier function. It is believed that if the ability to synthesize cholesterol in the epidermis decreases, the barrier function decreases and the skin's ability to recover from rough skin decreases. For this reason, cholesterol is commonly used in cosmetics, quasi-drugs, pharmaceuticals, etc., in the hope of maintaining the barrier function and improving rough skin. However, cholesterol is an amphiphilic, poorly soluble solid substance at room temperature, and has low solubility in cosmetic base materials, and in emulsions and the like, it precipitates over time, and in oil-based preparations such as beauty serum oils, it is difficult to form a preparation with a uniform solution, making it difficult to maintain a stable solution in the preparation. Although various formulations for stably incorporating cholesterol have been investigated (e.g., Patent Document 1), the dosage forms of preparations incorporating cholesterol are still limited, and a means for stably incorporating cholesterol is desired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2013-227293 Summary of the Invention [Problem to be solved by the invention]

[0004] To provide a means for stably blending cholesterol in an oil component. [Means for solving the problem]

[0005] The present invention includes the following embodiments. [1] A liquid oil composition comprising: (a) cholesterol; (b) isostearic acid; and (c) a liquid oil having a viscosity of 50 mPa s or less at 25°C; A cosmetic composition, wherein the mass ratio (a / b) of the component (a) to the component (b) is in the range of 1 / 8 to 1 / 20, and the mass ratio (b / c) of the component (b) to the component (c) is in the range of 10 / 1 to 1 / 1. [2] The composition according to [1], wherein the component (c) comprises at least one oil selected from the group consisting of hydrocarbon oils and ester oils. [3] The composition according to [1] or [2], wherein the component (c) includes at least one selected from the group consisting of light isoparaffin, light liquid isoparaffin, liquid isoparaffin, liquid paraffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate. [4] The composition according to any one of [1] to [3], wherein the component (c) includes at least one selected from the group consisting of light isoparaffin, light liquid isoparaffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate. [5] Based on the total amount of oily components contained in the composition, The content of the component (a) is 0.5 to 16 mass %, The content of the component (b) is 4 to 85% by mass, The composition according to any one of [1] to [4], wherein the content of the component (c) is 0.4 to 49 mass %. [6] The composition according to any one of [1] to [5], wherein the content of the component (a) is 0.5 to 5 mass% based on the total amount of the composition. [7] The cosmetic composition according to any one of [1] to [6], which is in a liquid form. [8] The cosmetic composition according to any one of [1] to [6], which is a non-aqueous composition. [9] The cosmetic composition according to any one of [1] to [6], which is an emulsion composition. Effect of the Invention

[0006] The present invention has one or more of the following advantages. (1) According to the present invention, a cosmetic composition is provided in which cholesterol is stably blended in an oil component. In some embodiments, the cosmetic composition inhibits crystalline precipitation of cholesterol over time. In some embodiments, the cosmetic composition inhibits crystalline precipitation of cholesterol at low temperatures. In some embodiments, the cosmetic composition allows for a high concentration of cholesterol to be stably blended in an oil component. (2) The cosmetic composition of the present invention has low skin irritation and is excellent in safety. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, the embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and can be modified and carried out as desired without departing from the gist of the present invention. The upper and lower limit values ​​of the numerical ranges described in this specification can be arbitrarily combined. For example, when "X to Y" and "Z to W" are described, the ranges of "X to W" and "Z to Y" are also included in the scope of the present invention as numerical ranges. In addition, the numerical range "lower limit value to upper limit value" described in this specification means not less than the lower limit value and not more than the upper limit value, unless otherwise specified.

[0008] <<Cosmetic composition>> A cosmetic composition according to one embodiment of the present invention (hereinafter also simply referred to as the "cosmetic composition") contains (a) cholesterol, (b) isostearic acid, and (c) a liquid oil having a viscosity of 50 mPa s or less at 25° C. In this embodiment, the mass ratio (a / b) of component (a) to component (b) is in the range of 1 / 8 to 1 / 20, and the mass ratio (b / c) of component (b) to component (c) is in the range of 10 / 1 to 1 / 1. Cholesterol is a poorly soluble substance, and thus it has been difficult to maintain a stable dissolved state in a formulation due to the occurrence of precipitation over time. As a solvent for dissolving cholesterol, there are some branched-chain saturated alcohols such as hexyldecanol and octyldodecanol, and esters of branched-chain saturated alcohols with high polarity such as octyldodecyl lactate, but from the viewpoint of skin irritation, a formulation in which cholesterol can be stably incorporated with a formulation that is less irritating to the skin than these branched-chain saturated alcohols and their esters has been desired. In the present invention, by blending (a) cholesterol with (b) isostearic acid and (c) a liquid oil having a viscosity of 50 mPa s or less at 25°C in a specific ratio, it is possible to obtain a composition that can stably dissolve cholesterol in an oil component and has excellent dissolution stability in which cholesterol precipitation is suppressed even at low temperatures.

[0009] As used herein, the terms "stably dissolved" or "dissolution stability" refer to the fact that no cholesterol precipitation is observed when the composition is kept at 5° C. for 24 hours. In this specification, the oil component means a component generally used as an oil component in the field of cosmetics. For example, it means a component having a solubility in water of less than 0.1% by mass (less than 1 g / L) at 25°C. Note that the oil component does not include surfactants. In this specification, "liquid oil" refers to an oil component that is liquid at 25° C. "Liquid at 25° C" refers to an oil whose viscosity is 7000 mPa s or less when measured at 25° C. and 1 atmospheric pressure using a B-type viscometer (rotor No. 2).

[0010] By blending (a) cholesterol with (b) isostearic acid, cholesterol can be dissolved at a high concentration. The mass ratio (a / b) of (a) cholesterol and (b) isostearic acid is in the range of 1 / 8 to 1 / 20. When a / b is greater than 1 / 8 (i.e., when b is smaller in a / b), cholesterol is not sufficiently dissolved, and crystal precipitation at low temperatures, crystal precipitation over time, and poor emulsification may occur. The lower limit of a / b in the mass ratio (a / b) of (a) cholesterol and (b) isostearic acid is not particularly limited, but when a / b is less than 1 / 20 (i.e., when b is larger in a / b), the blending ratio of cholesterol is reduced, limiting the amount of cholesterol that can be blended in the formulation, increasing the total amount of the oil phase, narrowing the range of emulsion formulation, and limiting the feeling of use. In some embodiments, the mass ratio (a / b) of (a) cholesterol and (b) isostearic acid can be in the range of, for example, 1 / 8 to 1 / 10. In some embodiments, the mass ratio (a / b) of (a) cholesterol and (b) isostearic acid can be, for example, in the range of 1 / 10 to 1 / 20.

[0011] The cosmetic composition of the present invention contains (c) a liquid oil having a viscosity of 50 mPa·s or less at 25°C, together with (b) isostearic acid. A mixed system of (a) cholesterol and (b) isostearic acid exhibits good solubility at room temperature, but has the problem that the solution solidifies and cholesterol precipitates in an environment of 5°C or less, and the precipitated cholesterol does not re-dissolve even when returned to room temperature. By mixing (c) a liquid oil having a viscosity of 50 mPa·s or less at 25°C in addition to (b) isostearic acid, it is possible to obtain a composition having excellent dissolution stability in which solidification at 5°C or less and cholesterol precipitation is suppressed even at low temperatures. In the cosmetic composition of the present invention, the mass ratio (b / c) of (b) isostearic acid and (c) liquid oil having a viscosity of 50 mPa·s or less at 25°C is in the range of 10 / 1 to 1 / 1. When b / c is greater than 10 / 1 (i.e., when c is smaller in b / c), cholesterol may crystallize and emulsify poorly at low temperatures (5°C or less). There is no particular lower limit for b / c in the mass ratio (b / c) of (b) isostearic acid and (c) liquid oil having a viscosity of 50 mPa·s or less at 25°C, but when b / c is less than 1 / 1 (i.e., when c is larger in b / c), the amount of component (c) increases, resulting in a smaller proportion of cholesterol in the formulation, leading to problems such as insufficient cholesterol being blended, an increase in the total amount of the oil phase narrowing the range of emulsion formulations, and limited usability. In some embodiments, the mass ratio (b / c) of (b) isostearic acid and (c) liquid oil having a viscosity of 50 mPa s or less at 25°C is preferably in the range of 5 / 1 to 1 / 1, and more preferably in the range of 2 / 1 to 1 / 1, in terms of stable solubility at low temperatures. Each of the components of the transparent aqueous composition of the present invention will now be described.

[0012] (a) Cholesterol The cosmetic composition contains cholesterol, which can have skin care effects such as enhancing the barrier function of the skin, suppressing water evaporation from the inside of the skin, and enhancing moisturizing power.

[0013] (b) Isostearic acid The cosmetic composition contains isostearic acid. In this specification, isostearic acid means a saturated side-chain fatty acid (branched stearic acid) having 18 carbon atoms. Isostearic acid may be used alone or in combination of two or more. Isostearic acid is a liquid oil at room temperature, and has the advantages of good breathability on the skin (low skin irritation), excellent oxidation stability, and a good feel when used. By blending isostearic acid, a composition can be obtained that has improved cholesterol dissolution stability, low skin irritation, and high safety.

[0014] Examples of isostearic acid include 18-carbon side chain fatty acid (methyl-branched isostearic acid) produced as a by-product during the production of dimer acid, 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-octanoic acid (aldol condensation type isostearic acid), and 2-heptylundecanoic acid (Guerbet reaction type isostearic acid).

[0015] Methyl-branched isostearic acid, which is a branched methyl group, is obtained, for example, as a by-product during the production of oleic acid dimer (for example, J. Amer. Oil Chem. Soc., 51, 522 (1974)) (Emery type isostearic acid). The starting material for dimer acid, which is the starting material for Emery type isostearic acid, may include not only oleic acid but also linoleic acid, linolenic acid, etc.

[0016] 5,7,7-Trimethyl-2-(1,3,3-trimethylbutyl)-octanoic acid can be produced by subjecting an isobutylene dimer to an oxo reaction to produce a branched aldehyde having 9 carbon atoms, followed by aldol condensation of this aldehyde to produce a branched unsaturated aldehyde having 18 carbon atoms, followed by hydrogenation and oxidation (aldol condensation type isostearic acid).

[0017] 2-Heptylundecanoic acid can be produced by subjecting nonyl alcohol to the Guerbet reaction and then oxidizing it (Guerbet reaction type isostearic acid).

[0018] There are no particular limitations on the isostearic acid to be blended in the cosmetic composition, and any of the above types can be used, but from the standpoint of availability and the like, methyl-branched isostearic acid is preferred.

[0019] (c) A liquid oil with a viscosity of 50 mPa·s or less at 25°C The cosmetic composition contains a liquid oil having a viscosity of 50 mPa·s or less at 25° C. (hereinafter also referred to as "additional liquid oil"). By blending a liquid oil (additional liquid oil) with a viscosity of 50 mPa·s or less at 25°C together with isostearic acid, it is possible to inhibit the solidification of isostearic acid at low temperatures (5°C or less), and thus inhibit the precipitation of cholesterol. Although the details of why the blending of the additional liquid oil inhibits the precipitation of cholesterol are unknown, it is speculated that by blending a liquid oil with a lower viscosity than isostearic acid (viscosity at 25°C: 56 mPa·s), the melting point of the composition is lowered, thereby inhibiting the precipitation of cholesterol at low temperatures. However, the present invention is not limited to this mechanism.

[0020] Examples of the additional liquid oil include hydrocarbon oil, ester oil, wax, fats and oils, silicone oil, ether, etc., and are not particularly limited as long as they have a viscosity of 50 mPa·s or less at 25° C. Among them, in terms of miscibility with isostearic acid, it is preferable to include at least one oil selected from the group consisting of hydrocarbon oils and ester oils.

[0021] The hydrocarbon oil may be one refined from petroleum crude oil or one extracted from natural plants or animals, so long as it is liquid at 25° C. Specific examples include light isoparaffin, light liquid isoparaffin, liquid isoparaffin, and liquid paraffin.

[0022] According to the standards for quasi-drug ingredients, light isoparaffin refers to a mixture of hydrocarbons mainly consisting of isoparaffin. According to the standards for quasi-drug raw materials, light liquid isoparaffin is a mixture of hydrocarbons with side chains obtained by copolymerizing isobutene and n-butene and then hydrogenating them, and its degree of polymerization is 4 to 6. According to the standards for quasi-drug ingredients, liquid isoparaffin is a mixture of hydrocarbons with side chains obtained by copolymerizing isobutene and n-butene and then hydrogenating the copolymer, and its degree of polymerization is 5 to 10. According to the standards for quasi-drug ingredients, liquid paraffin refers to a mixture of liquid hydrocarbons obtained from petroleum.

[0023] The ester oil is not particularly limited as long as it is an ester of alcohol and fatty acid, is liquid at 25° C., and has a viscosity of 50 mPa·s or less at 25° C., and fatty acid esters of lower alcohols, fatty acid esters of higher alcohols, fatty acid esters of polyhydric alcohols, etc. Among them, fatty acid esters of higher alcohols are preferred, and examples thereof include isodecyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate.

[0024] These additional liquid oils may be used alone or in combination of two or more. In some embodiments, the liquid oil having a viscosity of 50 mPa s or less at 5° C. contains at least one selected from the group consisting of light isoparaffin, light liquid isoparaffin, liquid isoparaffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate. When these are used, cholesterol precipitation is suppressed and cholesterol solubility is excellent. In a specific embodiment, the liquid oil having a viscosity of 50 mPa s or less at 25° C. includes at least one selected from the group consisting of light isoparaffin, light liquid isoparaffin, isodecyl pivalate, isostearyl pivalate, and 2-hexyldecyl stearate. These are preferred because they can provide an inhibitory effect on cholesterol precipitation with the addition of a small amount. In a specific embodiment, the liquid oil having a viscosity of 50 mPa s or less at 5° C. contains at least one selected from the group consisting of light isoparaffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate, which have excellent cholesterol precipitation suppression effects and excellent cholesterol solubility. In one embodiment, the liquid oil having a viscosity of 50 mPa s or less at 5° C. contains at least one selected from the group consisting of light isoparaffin, isodecyl pivalate, and isostearyl pivalate, which have an excellent effect of inhibiting cholesterol precipitation and are particularly excellent in cholesterol solubility.

[0025] In some embodiments, the liquid oil having a viscosity of 50 mPa·s or less at 5° C. comprises at least one selected from the group consisting of light isoparaffin, light liquid isoparaffin, liquid isoparaffin, and liquid paraffin.

[0026] (d) Other oily ingredients The cosmetic composition may contain oily components other than the above (a) cholesterol, (b) isostearic acid, and (c) additional liquid oil (hereinafter also referred to as "other oily components").

[0027] The other oily components are not particularly limited, and examples thereof include, other than the (c) additional liquid oil, higher monoalcohols, hydrocarbons, ester oils, oils and fats, fatty acids, waxes, silicone oils, etc. These may be used alone or in combination of two or more.

[0028] The higher monoalcohol is not particularly limited, but is preferably a straight-chained one, more preferably a straight-chained higher monoalcohol having 12 to 22 carbon atoms (more preferably 14 to 22 carbon atoms, and even more preferably 16 to 22 carbon atoms). Specific examples include cetanol, stearyl alcohol, cetostearyl alcohol, behenyl alcohol, and the like. The hydrocarbon is not particularly limited, and examples thereof include squalane, sugar squalane, α-olefin oligomer, petrolatum, and microcrystalline wax. The ester oil is not particularly limited, and for example, fatty acid esters of lower alcohols, fatty acid esters of higher alcohols, fatty acid esters of polyhydric alcohols, etc., having a viscosity of more than 50 mPa·s at 25° C. can be used. The oils and fats are not particularly limited, and examples thereof include olive oil, shea butter, grape seed oil, and the like. The wax is not particularly limited, and examples thereof include jojoba oil, beeswax, candelilla wax, and the like. The fatty acid is not particularly limited, and examples thereof include myristic acid, palmitic acid, and stearic acid.

[0029] In some embodiments, the cosmetic composition preferably contains 5 to 100% by mass of the total of (a) cholesterol, (b) isostearic acid, and (c) additional liquid oil, more preferably 10 to 100% by mass, and even more preferably 15 to 100% by mass, based on the total amount of oily components contained in the composition. By using such a composition, precipitation of cholesterol is suppressed, and a stable dissolved state can be maintained. In some embodiments, the cosmetic composition has a total content of the above-mentioned (a) cholesterol, (b) isostearic acid, and (c) additional liquid oil, relative to the total amount of oily components contained in the composition, of, for example, 50 to 100% by mass, or 60 to 100% by mass, or 70 to 100% by mass, or 80 to 100% by mass, or 90 to 100% by mass, or 95 to 100% by mass, or 98 to 100% by mass, or 99 to 100% by mass.

[0030] In some embodiments, the cosmetic composition preferably has a content of other oily components of 0 to 95 mass%, more preferably 0 to 90 mass%, and even more preferably 0 to 85 mass%, relative to the total amount of oily components contained in the composition. In some other embodiments, the cosmetic composition has, relative to the total amount of oily components contained in the composition, the content of other oily components is, for example, 0 to 50% by mass, or 0 to 40% by mass, or 0 to 30% by mass, or 0 to 20% by mass, or 0 to 10% by mass, or 0 to 5% by mass, or 0 to 2% by mass, or 0 to 1% by mass. In certain embodiments, the cosmetic composition is free of other oily ingredients.

[0031] (composition) The blending ratios of the above (a) cholesterol, (b) isostearic acid, and (c) additional liquid oil in the oil component are not particularly limited, so long as they are within the range of the above-mentioned mass ratio (a / b) of (a) cholesterol and (b) isostearic acid and the mass ratio (b / c) of (b) isostearic acid and (c) liquid oil having a viscosity of 50 mPa s or less at 25°C. In some embodiments, the cosmetic composition has a cholesterol content of (a) of preferably 0.5 to 16% by mass, more preferably 2 to 12% by mass, and even more preferably 4 to 10% by mass, based on the total amount of oily components contained in the composition. The cosmetic composition has an isostearic acid content of (b) of preferably 4 to 85% by mass, more preferably 20 to 80% by mass, and even more preferably 45 to 80% by mass, based on the total amount of oily components contained in the composition. The cosmetic composition has an additional liquid oil content of (c) of preferably 0.4 to 49% by mass, more preferably 10 to 48% by mass, and even more preferably 15 to 48% by mass, based on the total amount of oily components contained in the composition.

[0032] The proportion of the oily component in the cosmetic composition is not particularly limited as long as it is within a range that does not adversely affect the solubility of cholesterol, and is appropriately adjusted according to the formulation. In some embodiments, the cosmetic composition has a total content of oily components of preferably 5 to 100 mass%, more preferably 10 to 100 mass%, and even more preferably 15 to 100 mass%, relative to the total amount of the composition. In some other embodiments, the cosmetic composition has a total content of oily components, relative to the total amount of the composition, of preferably 50 to 100% by mass, or 60 to 100% by mass, or 70 to 100% by mass, or 80 to 100% by mass, or 90 to 100% by mass, or 95 to 100% by mass, or 98 to 100% by mass, or 99 to 100% by mass.

[0033] (e) Other ingredients The cosmetic composition may contain other components as necessary, provided that they do not adversely affect the solubility of cholesterol. Examples of other components include an aqueous component and a surfactant. The aqueous components include water, wetting agents, natural polymers, synthetic polymers, preservatives, and lower monoalcohols. In addition, other ingredients may include any ingredient contained in ordinary cosmetics, quasi-drugs, or pharmaceuticals, such as moisturizers, antioxidants, UV absorbers, thickeners, pH adjusters, powder ingredients, metal sequestering agents, coloring materials, various skin nutrients, and drugs, as needed. The content of other components in the cosmetic composition is not particularly limited as long as it is within a range that does not adversely affect the solubility of cholesterol, and is appropriately adjusted according to the dosage form. For example, the content of other components in the cosmetic composition is 0 to 95% by mass relative to the total amount of the composition.

[0034] (Method for producing cosmetic composition) The cosmetic composition can be produced according to a standard method, for example, by mixing and stirring (a) cholesterol, (b) isostearic acid, (c) additional liquid oil, if necessary (d) other oily components, and (e) other components in a suitable order, and then heating and homogenizing as necessary.

[0035] Typically, the cosmetic composition can be produced by a method including the following steps 1 and 2. Step 1: (a) cholesterol and (b) isostearic acid are mixed and the cholesterol is dissolved in the isostearic acid. Step 2: After step 1, further comprising (c) adding and mixing additional liquid oil. According to this method, a cosmetic composition in which cholesterol is stably dissolved can be easily obtained. In step 1, the mixing temperature of (a) cholesterol and (b) isostearic acid is preferably a temperature of 85° C. or higher (preferably 85 to 120° C., more preferably 85 to 95° C.) from the viewpoint of improving the solubility of cholesterol.

[0036] (Dosage form / use) The cosmetic composition of the present invention can be in various dosage forms, including, but not limited to, lotions, oils, emulsions, creams, and the like.

[0037] In some embodiments, the cosmetic composition is a non-aqueous composition. In some embodiments, the non-aqueous cosmetic composition contains the above-mentioned component (d) as necessary, in addition to the above-mentioned components (a) to (c). The cosmetic composition of this embodiment can be produced, for example, by a production method including mixing (a) cholesterol and (b) isostearic acid at a temperature of preferably 85° C. or higher (more preferably 85 to 120° C., and even more preferably 85 to 95° C.) to dissolve cholesterol in the isostearic acid, and then further adding and mixing (c) additional liquid oil and, as necessary, (d) other oily components.

[0038] In some embodiments, the cosmetic composition is liquid. In some embodiments, the liquid cosmetic composition contains the above-mentioned components (a) to (c), and, if necessary, the above-mentioned component (d). In some embodiments, the above-mentioned components (a) to (c), and, if necessary, the above-mentioned component (d), further contain water, an aqueous component, etc. The cosmetic composition of this embodiment can be produced, for example, by a production method including mixing (a) cholesterol and (b) isostearic acid at a temperature of preferably 85°C or higher (more preferably 85 to 120°C, even more preferably 85 to 95°C) to dissolve cholesterol in the isostearic acid, and then further adding and mixing (c) additional liquid oil and, if necessary, (d) other oily components, water, an aqueous component, etc.

[0039] In some embodiments, the cosmetic composition is an emulsion composition. In this specification, the term "emulsion composition" refers to a composition in which an oily component and an aqueous component are mixed together homogeneously by the aid of a surfactant or other component having emulsifying power. In some embodiments, the cosmetic composition, which is an emulsion composition, contains an oil component containing the above-mentioned components (a) to (c) and, if necessary, (d) other oil components, a surfactant, and an aqueous component. The cosmetic composition of this embodiment can be produced, for example, by mixing (a) cholesterol and (b) isostearic acid at a temperature of preferably 85° C. or higher (more preferably 85 to 120° C., and even more preferably 85 to 95° C.) to dissolve cholesterol in the isostearic acid, and then adding and mixing (c) additional liquid oil and, if necessary, (d) other oil components to form an oil phase, and then mixing the aqueous component and the surfactant, and emulsifying the mixture by stirring using a known stirring device such as a disperser mixer or a paddle mixer.

[0040] The cosmetic composition can be used for various cosmetic purposes. Examples of the cosmetic composition include skin care cosmetics such as lotion, milky lotion, cream, beauty essence, massage agent, pack agent, hand cream, body lotion, body cream, and sunscreen, finishing cosmetics such as foundation, eye shadow, eye liner, mascara, eyebrow, concealer, lipstick, and lip balm, and hair cosmetics such as hair mist, treatment, hair cream, hair shampoo, and hair rinse. Methods of use include using the cosmetic composition on hands, fingers, or cotton, and impregnating nonwoven fabrics and the like.

[0041] (characteristic) The cosmetic composition of the present invention has excellent dissolution stability. For example, the cosmetic composition preferably exhibits a small amount of cholesterol precipitation (for example, less than 1 / 3, preferably less than 1 / 4) after being left to stand for 24 hours after preparation at a low temperature (5° C. or lower), and more preferably exhibits no cholesterol precipitation. EXAMPLES

[0042] The present invention will be described in more detail below with reference to examples. Not limited to this. The blending amount and content of each component in the table are converted to the pure amount, and are expressed as "mass %" unless otherwise specified.

[0043] The raw material names of the various components used in the examples are shown below. Isostearic acid: Isostearic acid EX (Kyushu Alcohol Kogyo Co., Ltd.) Plant-derived methyl-branched isostearic acid Liquid paraffin: MORESCO White P-55 (MORESCO Corporation) Sugar squalane: Sugar squalane (Nikko Chemicals Co., Ltd.) Hexyldecanol: Lisonol 16SP (Kyukyu Alcohol Kogyo Co., Ltd.) Isotridecyl isononanoate: Salacos 913 (Nisshin Oillio Co., Ltd.) 2-Cetyl ethylhexanoate: Salacos 816T (Nisshin Oillio Co., Ltd.) Glyceryl triethylhexanoate: TIO (Nisshin Oillio Co., Ltd.) Octyldodecyl lactate: Cosmol 13 (Nisshin Oillio Co., Ltd.) 2-Hexyldecyl myristate: ICM-R (Nikko Chemicals Co., Ltd.) Isopropyl myristate: IPM-100 (Nikko Chemicals Co., Ltd.) Jojoba oil: Jojoba Oil S (Nikko Chemicals Co., Ltd.) Meadowfoam oil: Meadowfoam oil (Nikko Chemicals Co., Ltd.) Methylpolysiloxane: KF-96A 6cs (Shin-Etsu Chemical Co., Ltd.) Methylphenylpolysiloxane: KF-56A (Shin-Etsu Chemical Co., Ltd.) Light isoparaffin: Pearleem 3 (NOF Corporation) Light liquid isoparaffin: Pearleem 4 (NOF Corporation) Liquid isoparaffin: Pearleem 6 (NOF Corporation) Heavy fluid isoparaffin: Pearleem 24 (NOF Corporation) Isodecyl pivalate: Neolite 100P (Kyushu Alcohol Kogyo Co., Ltd.) Isostearyl pivalate: Neolite 180P (Kyushu Alcohol Kogyo Co., Ltd.) Isotridecyl isononanoate: KAK 139 (Kyukyu Alcohol Kogyo Co., Ltd.) Pentaerythritol tetraisostearate: KAK PTI (Kyoto Alcohol Industry Co., Ltd.) 2-Hexyldecyl stearate: ICS-R (Kyushu Alcohol Kogyo Co., Ltd.) Isostearyl isostearate: ISIS (Kyushu Alcohol Kogyo Co., Ltd.) Pentaerythritol tetra 2-ethylhexanoate: Salacos 5408 (Nisshin Oillio Co., Ltd.)

[0044] The viscosity of each component at 25° C. was measured using a TVB-25 viscometer (Toki Sangyo Co., Ltd.).

[0045] [Test Example 1: Dissolution test of cholesterol in various liquid oils] The solubility of cholesterol in various liquid oils was investigated. Specifically, cholesterol and various liquid oils were weighed and mixed, then heated and dissolved in a water bath at 85-90°C. The mixture was then cooled to room temperature and further to 5°C. The state of cholesterol dissolution after heating and dissolution and after cooling (room temperature to 5°C) were confirmed. The state of dissolution was visually observed and evaluated according to the following criteria. (Judgment criteria) A: Completely dissolved B: Partially dissolved (some residue remains) C: Not dissolved or precipitated D: Solidification The results are shown in the table below.

[0046] [Table 1]

[0047] As shown in Table 1, cholesterol was dissolved in isostearic acid at high temperatures (85°C to 95°C). When cholesterol was mixed with 5 times or more the amount of isostearic acid at room temperature, no solidification or precipitation of cholesterol was observed, and a good dissolved state was maintained. At a temperature of 5°C, precipitation occurred even when cholesterol was mixed with 10 times the amount of isostearic acid, and cholesterol could not be stably dissolved. On the other hand, the branched saturated alcohol (No. 1-10) and the highly polar branched ester (No. 1-19) showed good solubility at high temperatures (85°C to 95°C) and maintained a good solubility state even at room temperature and at a temperature of 5°C. However, although these solvents have excellent cholesterol solubility, they are highly polar and highly irritating to the skin, so it is desirable to use them in small amounts in cosmetics. In other liquid oils, cholesterol did not dissolve sufficiently, and solidification or precipitation was observed at room temperature.

[0048] [Test Example 2: Mixing additional liquid oil] An additional liquid oil was added to a mixture of cholesterol and isostearic acid to confirm the solubility of cholesterol. (Test Method) In the composition shown in the table below, (a) cholesterol and (b) stearic acid were weighed and mixed, and then dissolved by heating in a water bath at 85 to 95°C. The mixture was then cooled to room temperature, and either (c) a liquid oil having a viscosity of 50 mPa·s or less at 25°C (additional liquid oil) or (c') a liquid oil having a viscosity of more than 50 mPa·s at 25°C (other liquid oil) was added and thoroughly mixed to obtain a cosmetic composition. The composition was then stored in a 5°C incubator for 24 hours, after which the state of dissolution of cholesterol was confirmed. The state of dissolution of cholesterol at 25°C before and at 5°C after chilled storage was visually observed and evaluated according to the following criteria. (Judgment criteria) A: Completely dissolved B: Very little precipitation C: Acceptable slight precipitation D: Precipitation present E: Large amount of precipitation The results are shown in the table below.

[0049] [Table 2] [Table 3]

[0050] As shown in Tables 2 and 3, it was confirmed that the cosmetic compositions (Nos. 2-2 to 2-6, 2-10 to 2-20) containing (a) cholesterol together with (b) isostearic acid and (c) a liquid oil having a viscosity of 50 mPa·s or less at 25°C in specific ratios suppressed cholesterol precipitation even at low temperatures (5°C) and had excellent cholesterol solubility. Specifically, when light isoparaffin, light liquid isoparaffin, liquid isoparaffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, or isostearyl isostearate was used as the (c) additional liquid oil, it was confirmed that the cosmetic compositions suppressed cholesterol precipitation even at low temperatures (5°C) and had excellent cholesterol solubility. (c) When light isoparaffin, isodecyl pivalate, isostearyl pivalate, or 2-hexyldecyl stearate is used as the additional liquid oil, a small amount of the additional liquid oil (e.g., b / c≧10 / 5) can suppress cholesterol precipitation (Nos. 2-2, 2-11, 2-13, 2-15, and 2-17). (c) When light isoparaffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, or isostearyl isostearate was used as an additional liquid oil, it was confirmed that the solubility of cholesterol was further improved (Nos. 2-2, 2-3, 2-11 to 2-14, 2-15 to 2-18, and 2-20). In particular, when light isoparaffin, isodecyl pivalate, or isostearyl pivalate was used as the additional liquid oil (c), particularly excellent cholesterol solubility was achieved (Nos. 2-3, 2-11, and 2-16). On the other hand, (c) the cosmetic composition not containing any additional liquid oil (No. 2-1) and (c') the cosmetic compositions containing liquid oils having a viscosity of more than 50 mPa·s at 25°C (heavy liquid isoparaffin, pentaerythritol tetra-2-ethylhexanoate, pentaerythritol tetraisostearate) (Nos. 2-7 to 2-9, 2-21 to 2-24) caused cholesterol to precipitate at a low temperature (5°C) and were unable to stably dissolve cholesterol.

[0051] [Test Example 3: Examination of Mixing Ratio] The solubility of cholesterol was examined by changing the ratio of (a) cholesterol, (b) isostearic acid, and (c) light isoparaffin as an additional liquid oil. (Test Method) In the composition shown in the table below, (a) cholesterol and (b) isostearic acid were weighed and mixed, heated and dissolved in a water bath at 85 to 90°C, then cooled to room temperature, and (c) light isoparaffin was added as additional liquid oil and thoroughly mixed to obtain a cosmetic composition. After storing in a 5°C incubator for 24 hours, the state of dissolution of cholesterol was confirmed. The state of dissolution of cholesterol at 25°C before and at 5°C after cooling storage was visually observed and evaluated according to the following criteria. (Judgment criteria) A: Completely dissolved B: Very little precipitation C: Acceptable slight precipitation D: Precipitation present E: Large amount of precipitation The results are shown in the table below.

[0052] [Table 4]

[0053] As shown in Table 4, in the cosmetic compositions (Nos. 3-6, 3-7, 3-10, and 3-11) in which the mass ratio (a / b) of (a) cholesterol to (b) isostearic acid is 1 / 8 to 1 / 20 and the mass ratio (b / c) of (b) isostearic acid to (c) light isoparaffin is 10 / 2 to 10 / 10, cholesterol precipitation is inhibited even at low temperatures (5°C), and it is confirmed that the cosmetic compositions have excellent cholesterol solubility. On the other hand, in the cosmetic compositions (Nos. 3-7 and 3-8) in which the mass ratio (a / b) of (a) cholesterol to (b) isostearic acid was 1 / 5, the cholesterol solubility was excellent at room temperature, but a large amount of cholesterol precipitated at a low temperature (5°C).

[0054] Tables 1 to 4 show that by blending cholesterol in a specific ratio with isostearic acid and a liquid oil having a viscosity of 50 mPa s or less at 25°C, cholesterol precipitation is suppressed even at low temperatures, and cholesterol can be blended stably.

[0055] Although the preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. [Industrial Applicability]

[0056] The composition of the present invention is suitable for use as a cosmetic composition since it inhibits cholesterol precipitation even at low temperatures and enables cholesterol to be stably incorporated into an oily component.

Claims

1. (a) cholesterol; (b) isostearic acid; and (c) a liquid oil having a viscosity of 50 mPa·s or less at 25°C; A cosmetic composition, wherein a mass ratio (a / b) of the component (a) to the component (b) is in the range of 1 / 8 to 1 / 20, and a mass ratio (b / c) of the component (b) to the component (c) is in the range of 10 / 1 to 1 / 1.

2. The composition of claim 1 , wherein the component (c) comprises at least one selected from hydrocarbon oils and ester oils.

3. The composition according to claim 1 or 2, wherein the component (c) comprises at least one selected from the group consisting of light isoparaffin, light liquid isoparaffin, liquid isoparaffin, liquid paraffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate.

4. The composition according to claim 1 or 2, wherein the component (c) comprises at least one selected from the group consisting of light isoparaffin, isodecyl pivalate, isostearyl pivalate, isotridecyl isononanoate, 2-hexyldecyl stearate, and isostearyl isostearate.

5. Relative to the total amount of oily components contained in the composition, The content of the component (a) is 0.5 to 16 mass %, The content of the component (b) is 4 to 85 mass %, The composition according to claim 1 or 2, wherein the content of the component (c) is 0.4 to 49 mass%.

6. The composition according to claim 1 or 2, wherein the content of the component (a) is 0.5 to 16 mass % based on the total amount of the composition.

7. The cosmetic composition according to claim 1 or 2, which is in a liquid form.

8. The cosmetic composition according to claim 1 or 2, which is a non-aqueous composition.

9. The cosmetic composition according to claim 1 or 2, which is an emulsion composition.

Images