SPF enhancer

Abstract

To provide an SPF improver that can give a high SPF value without containing a high proportion of a UV scattering agent.SOLUTION: An SPF improver is a divalent metal salt of a C12-18 fatty acid.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an SPF improver.

Background Art

[0002] When ultraviolet rays hit the skin, they immediately cause sunburn such as erythema and darkening, and in the long term, they cause photoaging phenomena such as spots and wrinkles. Therefore, sunscreen cosmetics with an ultraviolet protection effect are used to protect the skin from ultraviolet rays. The ultraviolet protection effect of sunscreen cosmetics is quantified by the SPF value, and the higher the ultraviolet protection effect, the higher the SPF value.

[0003] In sunscreen cosmetics, ultraviolet absorbers and ultraviolet scattering agents are blended to obtain a high SPF value. Patent Document 1 discloses an oil-in-water type emulsified cosmetic characterized by containing an ultraviolet absorber, an acrylamide-based polymer, and an ultraviolet scattering agent, and it is described that it has a high SPF value. In addition, considering the influence of ultraviolet absorbers on the skin, sunscreen cosmetics containing encapsulated ultraviolet absorbers have been proposed. Patent Document 2 discloses a skin cosmetic for preventing ultraviolet rays, characterized by containing an encapsulated absorber, titanium dioxide, and methylpolysiloxane.

[0004] Furthermore, non-chemical type sunscreen cosmetics containing only an ultraviolet scattering agent without blending an ultraviolet absorber have come to be noticed. In order to obtain a high SPF value with only an ultraviolet scattering agent without blending an ultraviolet absorber, it is necessary to blend a high amount of the ultraviolet scattering agent. Patent Document 3 discloses an oil-in-water type emulsified sunscreen cosmetic characterized by containing a hydrophobically treated ultraviolet scattering agent, dipolyhydroxystearic acid ester, a liquid oil agent, and water, and it is described that it has good elongation during application while containing a high amount of the ultraviolet scattering agent.

[0005] On the other hand, metal soaps such as zinc fatty acid, calcium fatty acid, and magnesium fatty acid have been used as texture modifiers in makeup cosmetics. Metal soaps are also used in emulsified cosmetics to thicken the oil phase and improve stability. Patent document 4 discloses a water-in-oil emulsified cosmetic characterized by containing a water-soluble thickener and an emulsifying crosslinked elastomer or metal soap, and describes the stability-improving effect of metal soaps. However, it was not known that metal soaps could enhance the UV protection effect of UV scattering agents, thus acting as SPF improvers that allow for high SPF values ​​without using high concentrations of UV scattering agents. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-155417 [Patent Document 2] Japanese Patent Publication No. 2014-5251 [Patent Document 3] Japanese Patent Publication No. 2021-102608 [Patent Document 4] Japanese Patent Publication No. 2020-97553 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Currently, no technology has been developed that can achieve a high SPF value without using a high concentration of UV scattering agents. The object of the present invention is to provide an SPF enhancer that can achieve a high SPF value without using a high concentration of ultraviolet scattering agents. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors of the present invention have discovered that certain metal salts used as metal soaps can enhance the UV protection effect of UV scattering agents and can serve as SPF improvers that enable the achievement of high SPF values ​​without the need for high concentrations of UV scattering agents, thus completing the present invention. In other words, the present invention relates to the following [1] to [5].

[0009] [1] SPF improvers that are divalent metal salts of fatty acids with 12 to 18 carbon atoms. [2] The SPF improver described in [1] above, wherein the divalent metal is selected from zinc, calcium, and magnesium. [3] A composition containing an SPF improver, comprising the following components (A), (B), and (C). (A) Divalent metal salts of fatty acids with 12 to 18 carbon atoms (B) UV scattering agent (C) Liquid oil [4] A method for improving SPF, comprising incorporating a divalent metal salt of a fatty acid having 12 to 18 carbon atoms into a composition containing an ultraviolet scattering agent and a liquid oil. [5] Use of divalent metal salts of fatty acids with 12 to 18 carbon atoms as SPF improvers. [Effects of the Invention]

[0010] According to the SPF improving agent of the present invention, a high SPF value can be obtained without incorporating a high amount of ultraviolet scattering agent. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below. The SPF enhancer of the present invention contains a divalent metal salt of a fatty acid having 12 to 18 carbon atoms. Hereinafter, this divalent metal salt of a fatty acid having 12 to 18 carbon atoms may simply be referred to as a specific metal salt. In this specification, numerical ranges defined using the symbol "~" include the numbers at both ends (upper and lower limits) of "~". For example, "2~5" means 2 or more and 5 or less.

[0012] Examples of divalent metal salts of fatty acids having 12 to 18 carbon atoms used in the SPF improver of the present invention include zinc laurate, calcium laurate, magnesium laurate, zinc myristate, calcium myristate, magnesium myristate, zinc palmitate, calcium palmitate, magnesium palmitate, zinc stearate, calcium stearate, and magnesium stearate. The SPF improver of the present invention may contain one or more divalent metal salts of fatty acids having 12 to 18 carbon atoms. From the standpoint of improving SPF, the fatty acid in the divalent metal salt of a fatty acid having 12 to 18 carbon atoms is preferably a saturated fatty acid, and is particularly preferably stearic acid. From the standpoint of improving SPF, the divalent metal in the divalent metal salt of a fatty acid having 12 to 18 carbon atoms is preferably selected from zinc, calcium, and magnesium, with zinc being particularly preferred. Therefore, among the examples given above, zinc stearate is particularly preferred as the divalent metal salt of a fatty acid having 12 to 18 carbon atoms.

[0013] In the SPF improver of the present invention, the particle size of the divalent metal salt (specific metal salt) of a fatty acid having 12 to 18 carbon atoms is not particularly limited and can be any commonly used in the cosmetics field, but from the viewpoint of improving SPF, an average particle size of 1 to 50 μm is preferred. From the viewpoint of increasing the SPF value, the SPF improver of the present invention is preferably a combination of two or more specific metal salts with different average particle sizes. In particular, the SPF improver of the present invention is more preferably a combination of a specific metal salt with an average particle size of 1 to 5 μm and a specific metal salt with an average particle size of 10 to 50 μm, and is especially preferably a combination of a specific metal salt with an average particle size of 1 to 5 μm and a specific metal salt with an average particle size of 10 to 30 μm. In addition, when combining specific metal salts with an average particle diameter of 1 to 5 μm and specific metal salts with an average particle diameter of 10 to 30 μm, the mass ratio (mass of specific metal salt with an average particle diameter of 1 to 5 μm / mass of specific metal salt with an average particle diameter of 10 to 30 μm) is preferably 1 / 5 to 5, more preferably 1 / 3 to 3, and particularly preferably 1 / 2 to 2. In this specification, the average particle diameter is the average particle diameter (D50) measured by a laser scattering particle size distribution measuring device. The average particle diameter (D50) means the volume-based cumulative 50% particle diameter.

[0014] The present invention can also provide an SPF enhancer-containing composition containing the above-described SPF enhancer. The SPF enhancer-containing composition preferably contains an ultraviolet scattering agent in addition to the SPF enhancer. Since the SPF enhancer can enhance the ultraviolet protection effect of the ultraviolet scattering agent, the blending amount of the ultraviolet scattering agent can be made small compared to the case where the SPF enhancer is not used. Examples of the ultraviolet scattering agent include zinc oxide, titanium oxide, cerium oxide, iron oxide, chromium oxide, etc., and zinc oxide and titanium oxide are preferred.

[0015] The SPF enhancer-containing composition preferably has a liquid oil as the remainder other than the SPF enhancer, the ultraviolet scattering agent, and other general additives. That is, the SPF enhancer-containing composition of the present invention preferably contains (A) a divalent metal salt of a fatty acid having 12 to 18 carbon atoms, (B) an ultraviolet scattering agent, and (C) a liquid oil. Here, the divalent metal salt of a fatty acid having 12 to 18 carbon atoms in (A) may be referred to as component (A), the ultraviolet scattering agent in (B) as component (B), and the liquid oil in (C) as component (C). Component (A) is the SPF enhancer of the present invention described above. Also, the type of the ultraviolet scattering agent as component (B) is as described above. (C) The liquid oil is an oil that is liquid at 25°C and is usually used in cosmetics, pharmaceuticals, etc., that is, a liquid oil having fluidity at 25°C, and is selected from the group consisting of polar oils and non-polar oils. Examples of polar oils include triglycerides (vegetable oils) (e.g., olive oil) and ester oils (e.g., cetyl ethylhexanoate). Examples of non-polar oils include hydrocarbon oils (e.g., hydrogenated polyisobutene), silicone oils (e.g., dimethicone, cyclopentasiloxane), etc., and it is preferably a non-polar oil, more preferably a silicone oil, and particularly preferably cyclopentasiloxane.

[0016] The content of the SPF enhancer is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, and particularly preferably 2 to 10% by mass with respect to the total amount of the SPF enhancer-containing composition. The content of the ultraviolet scattering agent is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and particularly preferably 5 to 25% by mass with respect to the total amount of the SPF enhancer-containing composition. The content of the liquid oil is preferably 50 to 95% by mass, more preferably 55 to 90% by mass, and particularly preferably 60 to 85% by mass with respect to the total amount of the SPF enhancer-containing composition.

[0017] The SPF enhancer-containing composition of the present invention may contain additives. Examples of additives include solvents, solubilizers, dispersants, emulsifiers, oils, stabilizers, pH adjusters, antioxidants, sequestering agents, dyes, fragrances, pigments, etc., and one or more of these can be used as long as the characteristics of the present invention are not impaired. The SPF enhancer of the present invention and the SPF enhancer-containing composition containing the SPF enhancer can be made into pharmaceuticals, quasi-drugs, cosmetics, etc.

[0018] Furthermore, the present invention also provides a method for improving SPF by incorporating a divalent metal salt of a fatty acid having 12 to 18 carbon atoms into a composition containing an ultraviolet scattering agent and a liquid oil. When a divalent metal salt of a fatty acid having 12 to 18 carbon atoms is incorporated into a composition containing an ultraviolet scattering agent and a liquid oil, the above-described SPF improving agent-containing composition is obtained. Furthermore, in the present invention, the divalent metal salts of fatty acids having 12 to 18 carbon atoms as described above can be used as SPF improvers. As mentioned above, divalent metal salts of fatty acids with 12 to 18 carbon atoms can increase SPF values ​​and can therefore be applied to SPF improvement methods and used as SPF improvers. [Examples]

[0019] The present invention will be described in more detail below with reference to comparative examples and embodiments, but the present invention is not limited thereto.

[0020] Compositions containing SPF improvers, as shown in Table 1, were prepared and evaluated by the following method. In Table 1, the values ​​for each component represent the content (mass %) relative to the total amount of the SPF improver-containing composition, including the SPF improver.

[0021] The following ingredients were used. <(A): SPF enhancer> (A-1); Magnesium stearate "MM-2" (manufactured by NOF Corporation) (average particle size 3 μm) (A-2); Calcium stearate "MC-2" (manufactured by NOF Corporation) (average particle size 2 μm) (A-3); Zinc stearate "MZ-2" (manufactured by NOF Corporation) (average particle size 1.5 μm) (A-4); Zinc stearate (manufactured by NOF Corporation) (average particle size 20 μm)

[0022] <(B): UV scattering agent> (B-1); Titanium dioxide "MTX-05OTS" (manufactured by Teika Co., Ltd.) (B-2); Zinc oxide "MZX-508OTS" (manufactured by Teika Co., Ltd.)

[0023] <(C): Liquid oil> Cyclopentasiloxane

[0024] <Evaluation Method> (1) SPF value The SPF value of the SPF-enhancing agent-containing composition (approximately 1 g) was measured by the following method. The sample to be measured was 1.3 mg / cm³ 2 To achieve this, the solution was applied to a polymethyl methacrylate plate with a surface roughness of 6 μm (HELIOPLATE HD6, manufactured by Helioscience, France), and ultraviolet light was irradiated onto it. The amount of transmitted light was measured using a UV-2000S SPF analyzer (manufactured by Labsphere, USA). Each measurement was repeated five times, and the average value was used. (2) SPF improvement effect It was calculated using the following formula. A = SPF value of metal salt formulation (SPF value of the example) B = SPF value of the product without metal salts (SPF value of the control example) SPF improvement effect (%) = A / B × 100 The following criteria were used for evaluation, and "◎" and "○" were judged as passing. ◎: SPF improvement effect of 150% or more ○: SPF improvement effect of 130% or more but less than 150% △: SPF improvement effect is 110% or more but less than 130% ×: SPF improvement effect is less than 110%

[0025] Specifically, the SPF improvement effect was determined by comparing the SPF values ​​of Examples 1, 4-7 with Control Example 1, Example 2 with Control Example 2, and Example 3 with Control Example 3.

[0026] [Table 1]

[0027] As shown in Table 1, in control examples 1-3, the SPF value increased in proportion to the amount of UV scattering agent used. In Examples 1-3, the SPF value improved compared to Control Examples 1-3, confirming the SPF-improving effect. In Examples 1 and 4, an improvement in SPF was confirmed compared to Control Example 1. Furthermore, in Examples 1 and 4, although the amount of UV scattering agent was 2 / 3 that of Control Example 2, the SPF values ​​were similar. Examples 5-7 demonstrated superior SPF improvement compared to control example 1. In particular, Example 7 achieved a similar SPF value despite containing half the amount of UV scattering agent compared to control example 3.

Claims

1. A composition containing an SPF improver, comprising the following components (A), (B), and (C). (A) Divalent metal salts of fatty acids with an average particle size of 1 to 5 μm and 12 to 18 carbon atoms, and divalent metal salts of fatty acids with an average particle size of 10 to 50 μm and 12 to 18 carbon atoms. (B) UV scattering agent (C) Liquid oil

2. A method for improving SPF, comprising blending a divalent metal salt of a fatty acid having 12 to 18 carbon atoms and an average particle size of 1 to 5 μm, and a divalent metal salt of a fatty acid having 12 to 18 carbon atoms and an average particle size of 10 to 50 μm, into a composition containing an ultraviolet scattering agent and a liquid oil.

3. Use as an SPF improver by blending a divalent metal salt of a fatty acid having 12 to 18 carbon atoms and an average particle size of 1 to 5 μm, and a divalent metal salt of a fatty acid having 12 to 18 carbon atoms and an average particle size of 10 to 50 μm, into a composition containing an ultraviolet scattering agent and a liquid oil.

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