JP7789671B2 - Composition for external use on skin containing ascorbic acid and/or its salt - Google Patents

Description

The present invention relates to a composition for topical application to the skin containing ascorbic acid and/or its salts.

Ascorbic acid is known to exert a variety of effects, including anti-inflammatory, acne-fighting, whitening, anti-aging, antioxidant, cell activation by promoting the synthesis of biological components such as collagen, and suppressing ultraviolet-induced cell damage and DNA damage in epidermal keratinocytes. It is used as an external skin preparation for these expected effects. Techniques for improving the stability of ascorbic acid have been proposed (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2005-225865

The object of the present invention is to provide an ascorbic acid-containing topical skin composition that has a good feel and appearance.

The inventors' investigations have revealed that when using a composition containing ascorbic acid and/or its salt as a topical skin preparation, it can be difficult to achieve both a good feel when used and a good appearance.

As a result of extensive research to solve the problem, the present inventors have found that a topical skin composition excellent in feel and appearance can be obtained by incorporating (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and (C) 1 to 50% by mass of a diol having 3 carbon atoms, and have thus completed the present invention.

That is, the present invention provides the following external skin compositions.
Item 1.
A composition for external use on skin, comprising: (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms.
Item 2.
Item 2. The composition for external use on skin according to Item 1, wherein the concentration of the component (A) is 1 to 10% by mass.
Item 3.
Item 3. The composition for external use on skin according to Item 1 or 2, wherein the concentration of component (B) is 0.001 to 2% by mass.
Item 4.
Item 4. The composition for external use on skin according to any one of Items 1 to 3, further comprising (D) 1 to 15% by mass of water.
Item 5.
Item 5. The composition for external use on skin according to any one of Items 1 to 4, further comprising 1 to 20% by mass of (E) a lower alcohol.
Item 6.
Item 6. The composition for external application to skin according to any one of Items 1 to 5, which has a pH of 2 to 5.

Furthermore, the present invention provides the following methods for topical skin application compositions.
Section 7.
A method for inhibiting discoloration of a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, by blending (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and 1 to 50% by mass of (C) a diol having 3 carbon atoms.
Section 8.
A discoloration inhibitor for a composition comprising (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, and containing (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and (C) 1 to 50 mass % of a diol having 3 carbon atoms.
Item 9.
A method for improving the feel in use of a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, by using (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and (C) 1 to 50% by mass of a diol having 3 carbon atoms.
Item 10.
A usability improver for a composition comprising (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, and containing (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and (C) 1 to 50% by mass of a diol having 3 carbon atoms.

The present invention makes it possible to provide a topical skin composition that has excellent usability and appearance.

In this specification, the content unit "mass%" is synonymous with "g/100g."

[Skin external composition]
The composition for external use on skin of the present invention comprises:
(A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid;
The topical skin composition contains (B) at least one member selected from the group consisting of salicylic acid, a salt of salicylic acid, and a derivative of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms.

((A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid)
The ascorbic acid used in the present invention may be any ascorbic acid commercially available as a component of pharmaceuticals, quasi-drugs, or topical skin preparations in the field of cosmetics, and although not limited thereto, these generally refer to the L-isomer.

Salts of ascorbic acid can also be used. Here, the term "ascorbic acid salt" refers to a pharmaceutically acceptable salt. Examples include, but are not limited to, salts with organic bases (e.g., salts with tertiary amines such as trimethylamine salt, triethylamine salt, monoethanolamine salt, triethanolamine salt, and pyridine salt; basic ammonium salts such as arginine); and salts with inorganic bases (e.g., ammonium salt, alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; aluminum salt). Preferred salts of ascorbic acid are sodium salt and potassium salt.

In the present invention, ascorbic acid or a salt thereof may be used alone or in combination of two or more. From the viewpoint of significantly achieving the effects of the present invention, ascorbic acid is preferred. (A) Ascorbic acid or a salt thereof may be synthesized or commercially available.

In the topical skin composition of the present invention, the total content of component (A) relative to the total amount of the topical skin composition is appropriately set depending on the balance with other components.

The total content of component (A) relative to the total amount of the topical skin composition is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 5% by mass or less. The total content of component (A) relative to the total amount of the topical skin composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and even more preferably 3% by mass or more. The total content of component (A) relative to the total amount of the topical skin composition is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, even more preferably 2 to 9% by mass, and even more preferably 3 to 5% by mass.

((B) At least one selected from the group consisting of salicylic acid, a salt of salicylic acid, and a derivative of salicylic acid)
The salicylic acid or a derivative of salicylic acid used in the present invention is not particularly limited as long as it is used as a component of a pharmaceutical, quasi-drug or external skin preparation in the field of cosmetics.

Salts of salicylic acid can also be used. Here, salts of salicylic acid are pharmaceutically acceptable salts. Examples include, but are not limited to, alkali metal salts, alkaline earth metal salts, and salts with organic bases. Examples of salicylate salts include at least one selected from the group consisting of sodium salicylate, calcium salicylate, magnesium salicylate, and potassium salicylate.

From the viewpoint of achieving the most pronounced effects of the present invention, at least one selected from the group consisting of salicylic acid, sodium salicylate, calcium salicylate, magnesium salicylate, and potassium salicylate is preferred, with salicylic acid and/or sodium salicylate being more preferred. In another embodiment, a derivative of salicylic acid can also be used as component (B). Examples of such derivatives of salicylic acid include, but are not limited to, ethylene glycol salicylate, phenyl salicylate, methyl salicylate, 2-ethylhexyl salicylate, dipropylene glycol salicylate, and titanium salicylate. (B) Salicylic acid, a salt of salicylic acid, or a derivative of salicylic acid may be synthesized or commercially available.

In the topical skin composition of the present invention, the total content of component (B) relative to the total amount of the topical skin composition is not limited, but is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, even more preferably 0.01 mass% or more, and even more preferably 0.05 mass% or more.
The total content of component (B) relative to the total amount of the topical skin composition is not limited, but is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

The total content of component (B) relative to the total amount of the topical skin composition is preferably 0.001 to 5% by mass, preferably 0.005 to 2% by mass, more preferably 0.01 to 1% by mass, and even more preferably 0.05 to 0.5% by mass. Furthermore, taking into account cases where the composition is used as an acne medication, the total content may be 0.001 to 5% by mass, 0.01 to 4% by mass, 0.1 to 3% by mass, 0.5 to 2% by mass, etc.

In the topical skin composition of the present invention, the ratio of the amount of component (B) to component (A) is not particularly limited, but is preferably 0.0002 to 10 parts by mass, more preferably 0.001 to 1 part by mass, even more preferably 0.005 to 0.25 parts by mass, and even more preferably 0.01 to 0.2 parts by mass, per 1 part by mass of the total content of component (A).

((C) Diol having 3 carbon atoms)
The diol having three carbon atoms used in the present invention is not particularly limited as long as it is used as a component of topical skin preparations in the fields of pharmaceuticals, quasi-drugs, or cosmetics. Furthermore, commercially available diols such as these can be used as they are. Examples of diols having three carbon atoms include, but are not limited to, 1,3-propanediol (CAS No.: 504-63-2, English name: 1,3-Dihydroxypropane or Trimethylene Glycol) and propylene glycol (CAS No.: 57-55-6, English name: 1,2-Dihydroxypropane, Japanese name: 1,2-propanediol), and these may be used alone or in appropriate combination. From the viewpoints of reducing skin irritation, improving the feel during use, and suppressing discoloration, a combination of 1,3-propanediol and propylene glycol is also a preferred embodiment, and it is more preferable that component (C) contains at least 1,3-propanediol.

In the topical skin composition of the present invention, the total content of component (C) relative to the total amount of the topical skin composition is 1% by mass or more, preferably 5% by mass or more, and more preferably 10% by mass or more.
The total content of component (C) relative to the total amount of the external skin composition is 50% by mass or less, preferably 40% by mass or less, and more preferably 30% by mass or less.

The total content of component (C) relative to the total amount of the topical skin composition is 1 to 50% by mass, preferably 5 to 40% by mass, and more preferably 10 to 30% by mass.

In the topical skin composition of the present invention, the ratio of the amount of component (C) to component (A) is not particularly limited, but is preferably 0.05 to 100 parts by mass, more preferably 0.5 to 40 parts by mass, and even more preferably 1 to 15 parts by mass, per 1 part by mass of the total content of component (A).

The amount of propylene glycol in component (C) is 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the topical skin composition, and is preferably 50% by mass or less, 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less.
The total content of propylene glycol relative to the total amount of the topical skin composition is 0.1 to 50% by mass, 0.5 to 40% by mass, 1 to 40% by mass, preferably 5 to 30% by mass, and more preferably 10 to 20% by mass.

In the topical skin composition of the present invention, the ratio of the amount of propylene glycol to component (A) is not particularly limited, but is preferably 0.05 to 80 parts by mass, more preferably 0.5 to 30 parts by mass, and even more preferably 1 to 10 parts by mass, per 1 part by mass of the total content of component (A).

Of the components (C), the amount of 1,3-propanediol is 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the topical skin composition. The amount of 1,3-propanediol is 50% by mass or less, 40% by mass or less, 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 15% by mass or less.

The total content of 1,3-propanediol relative to the total amount of the topical skin composition is 0.1 to 50% by mass, 0.5 to 40% by mass, 1 to 30% by mass, preferably 5 to 20% by mass, and more preferably 10 to 15% by mass.

In the topical skin composition of the present invention, the ratio of the amount of 1,3-propanediol to component (A) is not particularly limited, but is preferably 0.05 to 60 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 7.5 parts by mass, per 1 part by mass of the total content of component (A).

In the topical skin composition of the present invention, component (C) may contain both propylene glycol and 1,3-propanediol. In this case, the combined amount of propylene glycol and 1,3-propanediol may be 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more, or may be 50% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less.
The combined amount of propylene glycol and 1,3-propanediol relative to the total amount of the topical skin composition may be 10% by mass to 50% by mass, 15% by mass to 45% by mass, 20% by mass to 40% by mass, or 25% by mass to 35% by mass.
Furthermore, when both propylene glycol and 1,3-propanediol are blended, the respective amounts may be 5 to 25% by mass, 5 to 20% by mass, 5 to 15% by mass, 10 to 25% by mass, 10 to 20% by mass, 10 to 15% by mass, 15 to 25% by mass, 15 to 20% by mass, or the like.

The topical skin composition of the present invention may contain (D) water and/or (E) a lower alcohol in addition to the above-mentioned components (A), (B), and (C), as long as the effects of the present invention are not impaired.

((D) Water)
The topical composition for skin of the present invention may contain water. The proportion of water is not limited, but the content of water relative to the total amount of the topical composition for skin is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass, and even more preferably 2 to 15% by mass.

In the topical skin composition of the present invention, the ratio of component (D) to component (A) is preferably 0.005 to 60 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.2 to 7.5 parts by mass, per 1 part by mass of the total content of component (A).

((E) Lower Alcohol)
The topical skin composition of the present invention may contain a lower alcohol. The lower alcohol used in the present invention is not particularly limited as long as it is used as a component of topical skin preparations in the fields of pharmaceuticals, quasi-drugs, or cosmetics. In this specification, the term "lower alcohol" refers to a C1-C6 alcohol. Of these, C1-C3 alcohols are particularly preferred. Examples of such alcohols include methanol, ethanol, n-propanol, and isopropanol, with ethanol being preferred.

In the topical skin composition of the present invention, the total content of component (E), if present, relative to the total amount of the topical skin composition is preferably 0.1 to 40% by mass, more preferably 0.5 to 10% by mass, and even more preferably 1 to 7% by mass.

Furthermore, although not limited thereto, typically, in the topical skin composition of the present invention, the amount of ethanol relative to the total amount of the topical skin composition is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 20% by mass.

In the topical skin composition of the present invention, the ratio of the amount of component (E) to the amount of component (A) is preferably 0.005 to 80 parts by mass, more preferably 0.05 to 10 parts by mass, and even more preferably 0.1 to 3.5 parts by mass, per 1 part by mass of the total content of component (A).

(Polyhydric alcohol)
The topical skin composition of the present invention may contain a polyhydric alcohol in addition to the above components (A), (B), and (C), as long as it does not impair the effects of the present invention.

The polyhydric alcohol used in the present invention is not particularly limited as long as it is used as a component of topical skin preparations in the fields of pharmaceuticals, quasi-drugs, or cosmetics. Polyhydric alcohols may also be added for moisturizing purposes or as solubilizers, although this is not a limitation. Specific examples include glycerin, diglycerin, dipropylene glycol, 1,3-butylene glycol, and 3-methyl-1,3-butanediol.

When included, the total content of polyhydric alcohols other than component (C) relative to the total amount of the topical skin composition of the present invention is preferably 0.1 to 60% by mass, more preferably 1 to 50% by mass, and even more preferably approximately 10 to 45% by mass.

(Vitamin E)
The topical skin composition of the present invention may contain, in addition to the above-mentioned components (A), (B), and (C), vitamin E compounds such as tocopherol, tocopherol salts, and tocopherol derivatives, as long as the effects of the present invention are not impaired. The tocopherol, tocopherol salts, and tocopherol derivatives used in the present invention may be compounds commonly used as components of topical skin preparations in the fields of pharmaceuticals, quasi-drugs, and cosmetics, and may be in any of the d-, l-, or dl-forms and may have any of the α, β, γ, and δ structures. Examples of tocopherols include d-α-tocopherol, d-β-tocopherol, d-γ-tocopherol, d-δ-tocopherol, l-α-tocopherol, l-β-tocopherol, l-γ-tocopherol, l-δ-tocopherol, and mixtures thereof such as dl-α-tocopherol, dl-β-tocopherol, dl-γ-tocopherol, and dl-δ-tocopherol. Tocopherol derivatives are not limited to, but tocopherol esters are preferred. Particular examples of tocopherol derivatives include tocopherol acetate, tocopherol nicotinate or a salt thereof, tocopherol succinate or a salt thereof, tocopherol linoleate, tocopherol phosphate or a salt thereof, tocopherol (linoleate/oleate), and tocopherol linoleate.

In the topical skin composition of the present invention, the total content of vitamin E relative to the total amount of the topical skin composition is not particularly limited, but is preferably 0.00001 to 10% by mass, more preferably 0.0001 to 5% by mass.

(Ascorbic acid derivatives)
The topical skin composition of the present invention may contain an ascorbic acid derivative in addition to the above-mentioned components (A), (B), and (C), as long as the effects of the present invention are not impaired. Examples of the ascorbic acid derivative used in the present invention include 3-O-ethyl ascorbic acid, L-ascorbic acid 2-glucoside, dehydroascorbic acid, sodium ascorbic acid phosphate, magnesium ascorbic acid phosphate, sodium ascorbic acid monophosphate, sodium ascorbic acid diphosphate, sodium ascorbic acid triphosphate, sodium ascorbic acid 2-sulfate, and salts thereof.

Salts are pharmaceutically acceptable salts. Examples of salts include, but are not limited to, salts with organic bases (e.g., salts with tertiary amines such as trimethylamine salt, triethylamine salt, monoethanolamine salt, triethanolamine salt, and pyridine salt; basic ammonium salts such as arginine); salts with inorganic bases (e.g., alkali metal salts such as ammonium salt, sodium salt, and potassium salt; alkaline earth metal salts such as calcium salt and magnesium salt; aluminum salt); and the like. Particularly preferred salts of 3-O-ethylascorbic acid are the sodium salt and potassium salt.

In the present invention, these ascorbic acid derivatives may be used alone or in combination of two or more.

In the topical skin composition of the present invention, the total content of ascorbic acid derivatives relative to the total amount of the topical skin composition is preferably 0.005 to 10% by mass, more preferably 0.01 to 5% by mass, even more preferably 0.02 to 3% by mass, and even more preferably 0.05 to 2% by mass.

(Surfactant)
The topical skin composition of the present invention may contain a surfactant, as long as it does not impair the effects of the present invention. When a surfactant is contained, it is not limited, but a nonionic surfactant is preferred, for example, polyoxyethylene hydrogenated castor oil 40, polyoxyethylene hydrogenated castor oil 60, polyoxyethylene hydrogenated castor oil 80, polyoxyethylene polyoxypropylene decyl tetradecyl ether, polyoxyethylene (20) polyoxypropylene (4) cetyl ether, polyoxyethylene (10) cetyl ether, polyoxyethylene (10) polyoxypropylene (4) cetyl ether, polyoxyethylene (10) oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene isoalcohol ether, PEG-8 glyceryl isostearate, polyoxyethylene sorbitan (20 E.O.) monolaurate, polyoxyethylene sorbitan isostearate (20 E.O.), polyoxyethylene sorbitan stearate (20 E.O.), polyoxyethylene sorbitan (20 E.O.) stearate, ... ), coconut oil fatty acid polyglyceryl-10, coconut oil fatty acid polyglyceryl-3, coconut oil fatty acid PEG-7 glyceryl, dioleic acid polyglyceryl-10, diisostearate polyglyceryl-10, triisostearate PEG-40 glyceryl isostearate, trilaurate polyglyceryl-10, tricaprylate hexaglyceryl, laurate polyglyceryl, myristate polyglyceryl, polyoxyethylene lauryl ether, etc. can be used, and particularly polyoxyethylene polyoxypropylene decyl tetradecyl ether, polyoxyethylene hydrogenated castor oil 40, polyoxyethylene hydrogenated castor oil 60, polyoxyethylene hydrogenated castor oil 80, polyoxyethylene sorbitan isostearate (20E.O.), polyoxyethylene sorbitan monolaurate (20E.O.), polyglyceryl laurate are preferred.

In the topical skin composition of the present invention, the total content of surfactants relative to the total amount of the topical skin composition is appropriately set depending on the balance with other ingredients. The total content of surfactants relative to the total amount of the topical skin composition is preferably 0.001 to 10% by mass, more preferably 0.005 to 7% by mass, and even more preferably 0.01 to 5% by mass.

(Other ingredients)
In addition to the above-mentioned components (A), (B), and (C), the topical skin composition of the present invention may further contain one or more combinations of various ingredients, such as whitening ingredients, anti-inflammatory ingredients, antibacterial ingredients, cell activating ingredients, astringent ingredients, antioxidant ingredients, acne-reducing ingredients, anti-aging ingredients, ingredients promoting biocomponent synthesis such as collagen, blood circulation promoting ingredients, moisturizing ingredients, and anti-aging ingredients, for the purpose of enhancing or supplementing the various effects of ascorbic acid or to impart other useful effects. Preferred are one or more of the whitening ingredients, anti-inflammatory ingredients, antibacterial ingredients, cell activating ingredients, astringent ingredients, antioxidant ingredients, anti-aging ingredients, and moisturizing ingredients. Particularly preferred combinations of these ingredients include combinations with whitening ingredients, combinations of whitening ingredients and antioxidant ingredients, combinations with antioxidant ingredients, combinations with anti-aging ingredients, and combinations of whitening ingredients and anti-aging ingredients. These components are not particularly limited as long as they have been used as components of topical skin preparations in the fields of pharmaceuticals, quasi-drugs, or cosmetics, or will be used in the future, and any components can be appropriately selected and used. Among these, isopropylmethylphenol, a bactericidal component, and/or dipotassium glycyrrhizinate, an anti-inflammatory component, are particularly preferred.

In addition to the above-mentioned components, the topical skin composition of the present invention can also contain solubilizing components, oils and fats, sugars, or transdermal absorption-promoting components. In particular, the inclusion of solubilizing components or oils and fats can further improve the stability, efficacy, and usability of ascorbic acid in aqueous solvents.

The topical skin composition of the present invention may contain various ingredients commonly used as ingredients in topical preparations in the fields of pharmaceuticals, quasi-drugs, and cosmetics, such as amino acids, irritation-reducing agents, thickeners, preservatives, UV protection agents, colorants, dispersants, additional pH adjusters, fragrances, etc., as needed, within quantitative and qualitative ranges that do not impair the qualities such as appearance stability and viscosity, or impair the effects of the present invention. These ingredients may be used alone, or two or more may be used in combination.

(form)
The topical skin composition of the present invention can be prepared in various desired forms, such as paste, mousse, gel, liquid, emulsion, cream, sheet (supported by a substrate), aerosol, spray, etc., by blending and mixing components (A), (B), and (C) and, if necessary, the above-mentioned optional components, and further blending, if necessary, other solvents or bases for commonly used topical preparations. These can be prepared by conventional methods in the art.

The topical skin composition of the present invention is particularly preferably a transparent or translucent composition in which ascorbic acid and/or a salt thereof has been solubilized. Here, "solubilized" is defined as follows: For example, when measured by ultraviolet-visible absorbance measurement using a spectrophotometer or photoelectric photometer UV-2450 (Shimadzu Corporation), the transmittance at a wavelength of 700 nm is in the range of 80-100%, preferably 85-100%, and more preferably 90-100%. Here, the transmittance of water is defined as 100%. The solubilized composition of the present invention has a transparent or translucent appearance. The transmittance measurement method is more specifically in accordance with the method described in the 16th Edition of the Japanese Pharmacopoeia [B], General Test Methods, 2. Physical Test Methods, Spectroscopic Measurement Methods, 2.24, Ultraviolet-Visible Absorbance Measurement Method.

(viscosity)
The topical skin composition of the present invention can be prepared as a composition having a suitable viscosity, particularly that desired when used for application to the skin. The viscosity of the topical skin composition of the present invention is not particularly limited, but is typically about 1 to 300 mPa·s, preferably about 1 to 200 mPa·s, more preferably about 1 to 100 mPa·s, and most preferably about 1 to 50 mPa·s, when measured at 25°C using an E-type viscometer. The viscosity measurement method is more specifically based on the method described in "2. Physical Test Methods, Other Physical Test Methods, 2.53 Viscosity Measurement Method, 2. Method 2, Rotational Viscometer Method, 2.1.3 Cone-Plate Rotational Viscometer" in the 16th Edition of the Japanese Pharmacopoeia [B] General Test Methods.

(pH)
The composition for external use on skin of the present invention may generally have a liquid pH of 1 to 8, but from the viewpoints of the stability of ascorbic acid, low irritation to the skin and mucous membranes, and a pleasant feel on the skin, the pH is preferably 2 to 7, more preferably 2 to 6, even more preferably 2 to 5.0, and most preferably 2 to 4.5. An acidic range is desirable.

(Application)
The topical skin composition of the present invention is particularly effective as a whitening agent, anti-inflammatory agent, and anti-aging agent, and has, for example, acne prevention and treatment and antioxidant effects. Furthermore, when applied to the skin, it may have the effects of increasing skin transparency, maintaining moisture, improving skin texture, and reducing roughness. Furthermore, it may have the effects of moisturizing skin with acne scars and pores, making pores less noticeable, leading to smooth skin, and moisturizing the skin, and it can also be used to prevent and treat age spots.

The topical skin composition of the present invention can be various skin compositions belonging to the fields of cosmetics, topical pharmaceuticals, or topical quasi-drugs, such as basic cosmetics such as serums, skin lotions, sunscreen creams, emulsions, creams, lotions, oils, and packs; makeup cosmetics such as foundations, lipsticks, lip balms, mascaras, eye shadows, eyeliners, eyebrow pencils, and nail polish; cleansers such as face washes, cleansers, and body washes; and various skin compositions belonging to the fields of cosmetics, topical pharmaceuticals, and topical quasi-drugs, such as anti-armpit odor agents, athlete's foot treatments, antipruritics, wound healing agents, cleansing agents, cleansers, anti-inflammatory and analgesic agents, acne treatments, hemorrhoid treatments, germicides, disinfectants, whitening agents, and UV protection agents. Due to its effects on the skin, the present invention is preferably used in products applied to the skin, such as topical skin preparations (preparations for the skin). The composition of the present invention can be used in known or conventional dosages and administration methods, from once to several times daily, depending on the intended use.

[Coloring suppression method]
The present invention also encompasses a method for inhibiting discoloration of a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid. According to the method for inhibiting discoloration of the present invention, a stable formulation containing ascorbic acid and inhibiting discoloration can be obtained by incorporating (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms. Specifically, the present invention relates to a method for inhibiting discoloration of a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, by incorporating (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms. Here, "inhibition of discoloration" refers to, but is not limited to, inhibition of discoloration due to ascorbic acid during storage (including improved transparency). Such inhibition of discoloration allows the topical skin composition of the present invention to exhibit a good appearance. Furthermore, "good appearance" due to such inhibition of discoloration also includes, for example, the absence of discoloration when the formulation adheres to clothing, etc.

In the present invention, the topical skin composition for inhibiting discoloration contains (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms, and the contents thereof are the same as those used in the topical skin composition described above.

[Coloration inhibitor]
The present invention also includes a discoloration inhibitor for a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid. The discoloration inhibitor of the present invention is a discoloration inhibitor for a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, and containing (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and 1 to 50% by mass of (C) a diol having 3 carbon atoms.

The discoloration inhibitor of the present invention is a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms, and the contents thereof, etc. are the same as those used in the topical skin composition described above.

[How to improve usability]
The present invention also encompasses a method for improving the feel of use of a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid. According to the method for improving the feel of use of the present invention, a good feel of use can be achieved by incorporating (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms. Specifically, the present invention relates to a method for imparting a good feel of use to a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, by incorporating (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms. Here, the feeling of use refers to, but is not limited to, low friction and smooth application.

In the method for improving the sensation of use of the present invention, the topical skin composition contains (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms, and the contents thereof, etc. are the same as those used in the topical skin composition described above.

[Usage improver]
The present invention also includes a usability improver for a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid. The usability improver of the present invention is a usability improver for a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, and containing (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid, and 1 to 50% by mass of (C) a diol having 3 carbon atoms.

The usability improver of the present invention is a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) at least one selected from the group consisting of salicylic acid, salts of salicylic acid, and derivatives of salicylic acid; and (C) 1 to 50% by mass of a diol having 3 carbon atoms, and the contents thereof, etc. are the same as those used in the topical skin composition described above.

Next, the present invention will be described in detail using examples, but the present invention is not limited to the following examples. Note that the unit of each component amount in the table is mass % unless otherwise specified in the table.

Compositions for topical use on the skin having the compositions shown in Tables 1 to 4 were prepared according to conventional methods.

[Test Example 1: Ascorbic Acid Coloration Inhibition Confirmation Test]
The compositions of the reference example, comparative example, and working example were evaluated for the presence or absence of inhibition of discoloration after storage at 60°C by visual inspection and a color difference meter. Specifically, the various components were mixed and dissolved according to the formulations shown in the tables to prepare compositions. 10 mL of the prepared composition was filled into a 20 mL screw-cap bottle and allowed to stand in a thermostatic chamber at 60°C for 5 days. After the 5-day measurement period had elapsed, the screw-cap bottle was removed from the thermostatic chamber and allowed to stand at 25°C before evaluation. Each composition was subjected to measurement to determine the presence and degree of discoloration.
Measurements were performed using a spectrophotometer CM-5 (manufactured by Konica Minolta, Inc.) by placing 2.5 mL of the test solution in a glass cell (CM-A97, 2 mm thick) and measuring the L value, a value, and b value in the CIELAB color system at 25° C. The measured values used were ΔL*Δa*Δb* when purified water was used as a blank.

The L* value (ΔL*) is a value related to lightness, the a* value (Δa*) is a value related to both directions between red and green, and the b* value (Δb*) is a value related to both directions between yellow and blue.

ΔE*ab is expressed by the following formula and is an indicator of the overall degree of coloration of the composition of the example or comparative example.

The ΔL increase rate was calculated using the following formula.
ΔL increase rate = ΔL (D65) (after storage) / ΔL (D65) (before storage)

The Δa increase rate was calculated using the following formula.
Δa increase rate = Δa (D65) (after storage) / Δa (D65) (before storage)

The Δb increase rate was calculated using the following formula.
Δb increase rate = Δb (D65) (after storage) / Δb (D65) (before storage)

The ΔE*ab increase rate was calculated using the following formula: where (D65) indicates that a D65 light source was used.
ΔE*ab(D65) increase rate=ΔE*ab(D65)(after storage)/ΔE*ab(D65)(before storage)

Here, the improvement rate (%) of Δa*(D65) in Example 1-1 is expressed as {(increase rate of Δa*(D65) in Reference Example 1-1 - increase rate of Δa*(D65) in Example 1-1)/(increase rate of Δa*(D65) in Reference Example 1-1)} x 100.
The improvement rate (%) of Δa*(D65) in Comparative Example 1-1 is expressed as {(increase rate of Δa*(D65) in Reference Example 1-2 - increase rate of Δa*(D65) in Comparative Example 1-1)/(increase rate of Δa*(D65) in Reference Example 1-2)} x 100.
The improvement rate (%) of Δb*(D65) in Example 1-1 is expressed as {(increase rate of Δb*(D65) in Reference Example 1-1 - increase rate of Δb*(D65) in Example 1-1)/(increase rate of Δb*(D65) in Reference Example 1-1)} x 100.
The improvement rate (%) of Δb*(D65) in Comparative Example 1-1 is expressed as {(increase rate of Δb*(D65) in Reference Example 1-2 - increase rate of Δb*(D65) in Comparative Example 1-1)/(increase rate of Δb*(D65) in Reference Example 1-2)} x 100.

Regarding the Δa value, the addition of salicylic acid to the composition of Example 1-1, which contained 30% 1,3-propanediol by mass, resulted in a color closer to that of water compared to Reference Example 1-1. On the other hand, the addition of salicylic acid to the system containing 60% 1,3-propanediol resulted in a color farther removed from that of water compared to Reference Example 1-2. Regarding the Δb value, the composition of Example 1-1, which contained 30% 1,3-propanediol by mass, exhibited a discoloration suppression effect due to salicylic acid. On the other hand, the composition of Comparative Example 1-1, which contained 60% 1,3-propanediol by mass, did not exhibit a discoloration suppression effect and exhibited a worsening effect. The addition of salicylic acid further suppressed discoloration in the composition of Example 1-1. Furthermore, the composition of Comparative Example 1-1 was significantly inferior to the composition of Example 1-1 in all of the evaluated indicators.

Here, the improvement rate (%) of ΔL*(D65) for each Example is expressed as {(increase rate of ΔL*(D65) for each Reference Example - increase rate of ΔL*(D65) for each Example)/increase rate of ΔL*(D65) for each Reference Example} x 100.
The improvement rate (%) of ΔL*(D65) of the comparative example is expressed as {(increase rate of ΔL*(D65) of the reference example - increase rate of ΔL*(D65) of the comparative example)/increase rate of ΔL*(D65) of the reference example} x 100.
The improvement rate (%) of ΔE*ab(D65) is expressed as {(increase rate of ΔE*ab(D65) of each reference example - increase rate of ΔE*ab(D65) of each example) / increase rate of ΔE*ab(D65) of each reference example} x 100.
The improvement rate (%) of ΔE*ab(D65) of the comparative example is expressed as {(increase rate of ΔE*ab(D65) of the reference example - increase rate of ΔE*abD65) of the comparative example)/increase rate of ΔE*ab(D65) of the reference example} x 100.
Each reference example is a composition obtained by omitting salicylic acid from the composition of each example or comparative example, and in Tables 2 and 3, it refers to the composition to the left of the respective example or comparative example.

In the composition of the example containing 30% by mass of propylene glycol, the brightness-improving effect of salicylic acid was observed. On the other hand, in the composition containing 60% by mass of propylene glycol, this effect was not observed. The same was true for compositions containing propanediol. Furthermore, the same was true when bases other than propylene glycols were used.
In the composition containing 30% by weight of propylene glycol, the brightness-improving effect of salicylic acid was observed. On the other hand, in the composition containing 60% by weight of propylene glycol, this effect was not observed. The same was true for propanediol. Furthermore, the same results were obtained when bases other than propylene glycols were used.

Furthermore, these effects were observed in compositions of the examples that used a mixture of 1,3-propanediol and propylene glycol, and the effects were also confirmed in compositions of the examples in which the total content of 1,3-propanediol and propylene glycol was 15% by mass. The effects were also confirmed when polyethylene glycol was used as the base or when the amount of salicylic acid was reduced.

All of the compositions of the examples had reduced discoloration, a more subdued overall color, and high transparency when compared to the reference examples or comparative examples.

[Test Example 2: Test to confirm improvement in friction]
(static friction coefficient)
Artificial leather (Suprare PBZ13001 (Idemitsu Technofine Co., Ltd.)) was attached to the moving table of the friction tester, and 1 mL of each composition was spread on the artificial leather so that it was thoroughly distributed directly under the contact. Next, a 50 g weight was attached to the measurement unit. The contact was attached to the measurement unit, and measurements were performed 1,000 times per second for 20 seconds. The average value of the friction coefficient obtained from the measurement results at the start of movement was calculated and used as the friction coefficient (μk) of the formulation. Note that a "tactile contact imitating a fingerprint pattern" was used as the contact of the friction tester (Tribmaster TL201Ts, manufactured by Trinity Labs).
Measurement conditions: Weight: 50g, Measurement time: 20 seconds, Movement distance: 10cm, Movement speed: 5mm/s, Value measured every 1msec.

Here, the friction improvement rate (%) for each Example or Comparative Example is expressed as {(friction coefficient of each Reference Example - friction coefficient of each Example or Comparative Example) / friction coefficient of each Reference Example} x 100. Each Reference Example is a composition obtained by removing salicylic acid from the composition of each Example or Comparative Example, and refers to the composition to the left of the respective Example or Comparative Example in Tables 4 to 6.

When salicylic acid was added to 30% by mass of 1,3-propanediol, friction decreased. At 60% by mass of 1,3-propanediol, no improvement was observed and friction increased. Furthermore, the coefficient of friction of Example 3-1 was lower than any of the reference examples or comparative examples, confirming the smoothness of the composition when first applied to the skin.

Furthermore, these effects were observed in compositions of the examples that used a mixture of 1,3-propanediol and propylene glycol, and the effects were also confirmed in compositions of the examples in which the total content of 1,3-propanediol and propylene glycol was 15% by mass. The effects were also confirmed when polyethylene glycol was used as the base or when the amount of salicylic acid was reduced.

(dynamic friction coefficient)
The artificial leather was attached to the moving table of the friction tester, and 1 mL of the test formulation was spread on the artificial leather so that it was thoroughly distributed directly under the contact. Next, a 50 g weight was attached to the measurement unit. The contact was attached to the measurement unit, and measurements were performed 1000 times per second for 20 seconds. The average value of the friction coefficient obtained from the measurement results 5 to 15 seconds after the start of measurement was calculated and used as the friction coefficient (μk) of the formulation. Note that a "tactile contact imitating a fingerprint pattern" was used as the contact of the friction tester (Tribmaster TL201Ts, manufactured by Trinity Labs).
Measurement conditions: Weight: 50g, Measurement time: 20 seconds, Movement distance: 10cm, Movement speed: 5mm/s, Value measured every 1msec.

Here, the friction improvement rate (%) for each Example or Comparative Example is expressed as {(friction coefficient of each Reference Example - friction coefficient of each Example or Comparative Example) / friction coefficient of each Reference Example} x 100. Each Reference Example is a composition obtained by removing salicylic acid from the composition of each Example or Comparative Example, and refers to the composition to the left of the respective Example or Comparative Example in Table 7.

When salicylic acid was added to 30% by mass of 1,3-propanediol, friction decreased. At 60% by mass of 1,3-propanediol, no improvement was observed and friction increased. Furthermore, the coefficient of friction of Example 4-1 was lower than any of the reference examples or comparative examples, confirming the smoothness of the composition when applied to the skin.

[Prescription example]
Formulation examples are shown in Tables 8 and 9 below. All formulation examples are beauty serums, and the contents in the formulation examples are all in mass %.

Claims (7)

A composition for external use on skin, comprising: (A) 0.5 to 5 % by mass of at least one member selected from the group consisting of ascorbic acid and salts of ascorbic acid; (B) 0.001 to 5% by mass of at least one member selected from the group consisting of salicylic acid and salts of salicylic acid; (C) 1 to 50% by mass of a diol having 3 carbon atoms; and (D) 0.1 to 30% by mass of water. The topical skin composition according to claim 1, further comprising 1 to 20% by mass of (E) a lower alcohol. The topical skin composition according to claim 1 or 2, having a pH of 2 to 5. A method for inhibiting discoloration of a topical skin composition containing (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, by blending 0.5 to 5 mass% of at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, (B) 0.001 to 5 mass% of at least one selected from the group consisting of salicylic acid and salts of salicylic acid, (C) 1 to 50 mass% of a diol having 3 carbon atoms, and (D) 0.1 to 30 mass% of water. A discoloration inhibitor for a composition for external use on skin, comprising (A) 0.5 to 5% by mass of at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, and containing (B) 0.001 to 5% by mass of at least one selected from the group consisting of salicylic acid and salts of salicylic acid, (C) 1 to 50 % by mass of a diol having 3 carbon atoms, and (D) 0.1 to 30% by mass of water. A method for improving the feel when used in a composition for external use on skin, which contains 0.5 to 5 % by mass of (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, by using 0.5 to 5% by mass of (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, 0.001 to 5% by mass of (B) at least one selected from the group consisting of salicylic acid and salts of salicylic acid, 1 to 50 % by mass of (C) a diol having 3 carbon atoms, and 0.1 to 30% by mass of (D) water. A usability improver for a topical skin composition containing 0.5 to 5 mass% of (A) at least one selected from the group consisting of ascorbic acid and salts of ascorbic acid, and containing 0.001 to 5 mass% of (B) at least one selected from the group consisting of salicylic acid and salts of salicylic acid, 1 to 50 mass% of (C) a diol having 3 carbon atoms, and 0.1 to 30 mass% of (D ) water .