Water-in-oil emulsion composition containing salicylic acid

Abstract

The purpose of the present invention is to provide a water-in-oil emulsion composition that is stable over a long period of time without allowing syneresis to occur, even when a relatively large quantity of salicylic acid has been blended therein, and furthermore does not lose usability over time and can be applied in a make-up cosmetic. The present invention relates to a water-in-oil emulsion composition that is characterized by including: (a) 0.5 mass% or more of salicylic acid; (b) an organic modified clay mineral; (c) a sorbitan fatty acid ester; and (d) a coloring material.

Description

[Technical Field]

[0001] The present invention relates to a water-in-oil emulsion composition, and more particularly to a water-in-oil emulsion composition capable of stably incorporating a relatively large amount of salicylic acid, and an emulsion cosmetic using the same. [Background technology]

[0002] Salicylic acid is known as an effective compound for treating relatively mild acne. Furthermore, salicylic acid derivatives such as 4-methoxysalicylate exhibit a whitening effect by improving and preventing abnormal melanin pigmentation when applied to the skin. However, when salicylic acid or its derivatives are incorporated into a water-in-oil emulsion composition, the emulsion particles tend to coalesce over time, destabilizing the system and resulting in separation (syneresis).

[0003] Patent Document 1 discloses a water-in-oil skin whitening cosmetic formulation containing 4-methoxysalicylate, a salicylic acid derivative. The cosmetic formulation is said to have a non-sticky, moist feel when used, and excellent stability over time, regardless of the container material, due to the incorporation of an organically modified clay mineral in combination with oleic acid and / or isostearic acid.

[0004] However, when 4-methoxysalicylate was replaced with salicylic acid in the cosmetic composition of Patent Document 1, the viscosity of the system tended to increase over time, making it difficult to use. Furthermore, the cosmetic composition of Patent Document 1 is a skin care cosmetic composition intended for whitening, and is not intended to contain coloring materials (powder) such as pigments. In fact, Patent Document 1 does not mention coloring materials, and the formulations specifically described do not include coloring materials. Therefore, it is unclear what changes would occur if coloring materials were added to the cosmetic composition of Patent Document 1 and used as a makeup cosmetic composition. [Patent Document 1] Patent No. 5164292 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide a water-in-oil emulsion composition that is stable and does not undergo syneresis over a long period of time even when a relatively large amount of salicylic acid is incorporated, that does not deteriorate in usability over time, and that can be applied to makeup cosmetics. [Means for solving the problem]

[0006] As a result of extensive research to solve the above problems, the present inventors have found that by blending a sorbitan fatty acid ester into a water-in-oil emulsion composition containing 0.5% by mass or more of salicylic acid, an organically modified clay mineral, and a colorant, it is possible to obtain a water-in-oil emulsion composition that is stable over a long period of time and maintains good usability, and have completed the present invention.

[0007] That is, the present invention provides: (a) 0.5% by weight or more of salicylic acid; (b) organically modified clay minerals; (c) sorbitan fatty acid esters; and (d) a coloring material. [Effects of the Invention]

[0008] The composition of the present invention is extremely stable over time even when it contains a relatively high concentration of salicylic acid, which is known to have a tendency to disrupt water-in-oil emulsions. At the same time, the viscosity does not change much over time, and good usability is maintained for a long period of time. Furthermore, the composition does not produce color streaks, making it particularly suitable for use as a makeup cosmetic. DETAILED DESCRIPTION OF THE INVENTION

[0009] As described above, the water-in-oil emulsion composition of the present invention contains (a) salicylic acid, (b) an organically modified clay mineral, (c) a sorbitan fatty acid ester, and (d) a coloring material as essential components. These components are described in detail below.

[0010] (a) Salicylic acid Salicylic acid is known to be effective in treating relatively mild acne, and is a known ingredient that has been incorporated into cosmetics for some time. While conventional cosmetics contain only small amounts of salicylic acid, the composition of the present invention is characterized by its ability to stably contain at least 0.5% by mass of salicylic acid. The amount of salicylic acid in the composition of the present invention is 0.5% by mass or more, and although there is no particular upper limit, it is usually 20% by mass or less, preferably about 10% by mass or less.

[0011] Since salicylic acid has low solubility in water, when preparing the composition of the present invention, it is preferable to dissolve salicylic acid in an appropriate amount of alcohol (ethanol) and then incorporate the solution. However, if the salicylic acid in the composition of the present invention is replaced with a salicylic acid derivative (alkoxysalicylic acid) such as 4-methoxysalicylate, the viscosity tends to increase over time, making it difficult to use, which is undesirable. Therefore, in this invention, "salicylic acid" includes salicylic acid and its salts, but does not include salicylic acid derivatives such as alkoxysalicylic acids.

[0012] (b) Organically modified clay minerals The organically modified clay mineral used in the composition of the present invention is preferably a clay mineral obtained by adding a quaternary ammonium salt compound to a natural or synthetic smectite clay mineral such as bentonite via an ion exchange reaction. The organically modified clay mineral is not particularly limited as long as it is pharmaceutically acceptable, and examples include dimethylammonium hectorite, benzyldimethylstearylammonium hectorite, and magnesium aluminum silicate treated with distearyldimethylammonium chloride. Preferred commercially available products include dimethyldistearylammonium hectorite sold by Elementis under the name "Benton 38VCG" and benzyldimethylstearylammonium hectorite sold by Elementis under the name "Benton 27VCG."

[0013] One or more types of organically modified clay minerals can be blended. The amount of organically modified clay mineral blended is preferably 0.1 to 5.0% by mass, for example, 1.5 to 5.0% by mass, based on the total amount of the composition. If the amount is less than 0.1% by mass, emulsion stability tends to decrease, and if the amount is more than 5.0% by mass, stickiness tends to occur, resulting in a poor feel when used.

[0014] (c) Sorbitan fatty acid ester The sorbitan fatty acid ester used in the composition of the present invention is an ester of a fatty acid having 12 to 20 carbon atoms and sorbitol. Examples of fatty acids having 12 to 20 carbon atoms include stearic acid, isostearic acid, and sesquiisostearic acid. Specific examples include sorbitan monoisostearate and sorbitan sesquiisostearate, with sorbitan sesquiisostearate being preferred. Examples of commercially available products include "Estemol 182V" (manufactured by Nisshin Oillio Co., Ltd.) and "Emalex SPIS-150" (manufactured by Nippon Emulsion Co., Ltd.).

[0015] The amount of sorbitan fatty acid ester in the composition of the present invention is usually 0.1 to 4.0% by mass, preferably 0.5 to 3.0% by mass, and more preferably 0.5 to 1.5% by mass. If it is less than 0.1% by mass, sufficient emulsion stability cannot be obtained, and if it is more than 4.0% by mass, stickiness may occur.

[0016] Patent Document 1 describes an invention in which emulsion stability is improved by incorporating oleic acid and / or isostearic acid in a system in which the salicylic acid derivative potassium 4-methoxysalicylate and an organically modified clay mineral coexist. Patent Document 1 describes (paragraph 0024) that a low-HLB (7 or less) emulsifier can be incorporated in addition to a liquid fatty acid such as isostearic acid, and examples of such low-HLB emulsifiers include sorbitan fatty acid esters. However, when the salicylic acid derivative in the system of Patent Document 1 is replaced with salicylic acid and a colorant is further incorporated, viscosity changes over time are observed even in the presence of isostearic acid. It was also discovered for the first time that in a system in which salicylic acid, an organically modified clay mineral, and a colorant coexist, the incorporation of a sorbitan fatty acid ester results in a highly stable composition without viscosity changes over time, even without the inclusion of a liquid fatty acid. Therefore, the compositions of the present invention encompass embodiments that do not contain liquid fatty acids such as isostearic acid or oleic acid.

[0017] (d) Color material The coloring materials to be blended in the composition of the present invention may be pigments and pearl pigments, which are usually blended in makeup cosmetics. Specifically, inorganic white pigments (titanium dioxide, zinc oxide), inorganic red pigments (iron oxide (red iron), iron titanate), inorganic brown pigments (γ-iron oxide), inorganic yellow pigments (yellow iron oxide, ochre), inorganic black pigments (black iron oxide, carbon, low-order titanium dioxide), inorganic purple pigments (mango violet, cobalt violet), inorganic green pigments (chromium oxide, chromium hydroxide, cobalt titanate), inorganic blue pigments (ultramarine, Prussian blue), pearl pigments (titanium dioxide coated mica, titanium dioxide coated bismuth oxychloride, titanium dioxide coated talc, colored titanium dioxide coated mica, bismuth oxychloride, fish scale foil), metal powder pigments (aluminum powder, copper powder), organic pigments (Red No. 202, Red No. 205, Red No. 220, Red No. 228, Red The pigments may be selected from, but are not limited to, one or more of the following: organic pigments of zirconium, barium, and aluminum lakes (red 3, red 104, red 227, red 401, orange 205, yellow 4, yellow 202, green 3, blue 1), natural pigments (chlorophyll, carotenoids (β-carotene), carthamine, cochineal, chalcone, curcumin, betanin, flavonol, flavone, anthocyanidin, anthraquinone, naphthoquinone), and functional pigments (boron nitride, photochromic pigments, synthetic fluorphlogopite, iron-containing synthetic fluorphlogopite, and fine particle composite powder (hybrid fine powder)).

[0018] The powdered colorant such as a pigment may be surface-untreated, or may be surface-treated with an organosilane compound, a silicone compound, a fluorine compound, a silane coupling agent, a fluorine resin, a fatty acid, a fatty acid soap, lauroyl lysine, or the like.

[0019] The composition of the present invention can exhibit the effect of preventing color stripes by containing 0.1% by mass or more of a coloring material relative to the total amount of the composition. Therefore, the amount of coloring material in the composition of the present invention can be 0.1% by mass or more. In particular, when the composition of the present invention is used as a makeup cosmetic, the amount of coloring material is preferably 1.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 10% by mass or more. If the amount is less than 1.0% by mass, a sufficient makeup effect cannot be obtained. There is no particular upper limit for the amount of coloring material, but it is usually 40% by mass or less, preferably 30% by mass or less. If the amount exceeds 40% by mass, stability may decrease.

[0020] The composition of the present invention is a water-in-oil emulsion composition, and therefore contains oil that constitutes the outer phase of the emulsion and water that constitutes the inner phase. The oil constituting the external phase is not particularly limited as long as it is an oil that can be used in cosmetics, etc., but it is preferable that it contains silicone oil. As the silicone oil, it is particularly preferable to use a volatile silicone oil, and in particular, a volatile linear silicone oil (1.5cs, 2cs, etc.). The amount of oil in the composition of the present invention is about 1 to 30% by mass. The water constituting the internal phase can hold hydrophilic components such as alcohol (ethanol), etc. The amount of water in the composition of the present invention is about 20 to 40% by mass.

[0021] In addition to the above-mentioned essential components (a) to (d), oil, and water, the composition of the present invention may contain other optional components that are commonly used in cosmetics, pharmaceuticals, etc., within the range that does not impair the effects of the present invention.

[0022] For example, by blending a polyether-modified silicone into the composition of the present invention, syneresis stability can be further improved. The preferred material for use in the present invention is a polyether-modified silicone having a polyoxyalkylene group grafted to a polysiloxane skeleton, which may optionally be alkyl-co-modified. Polyether-modified silicones (linear type) having a linear polysiloxane skeleton and polyether-modified silicones (branched type) having a branched polysiloxane skeleton can be used, but branched polyether-modified silicones are preferred in terms of improved stability. Furthermore, although not particularly limited, polyether-modified silicones having an HLB of preferably 6.0 or less, more preferably 5.0 or less, and preferably 3.0 or more, and polyether-modified silicones that are not alkyl-co-modified are preferably used.

[0023] Specific examples of polyether-modified silicones include PEG-3 dimethicone, PEG-10 dimethicone, cetyl PEG / PPG-10 / 1 dimethicone (all linear types), PEG-9 polydimethylsiloxyethyl dimethicone (all branched types), etc. Among these, PEG-9 polydimethylsiloxyethyl dimethicone is particularly preferred.

[0024] When polyether-modified silicone is added, the amount added is preferably 0.1 to 5 mass % of the total amount of the composition, more preferably 1 to 4 mass %, and particularly preferably 2 to 3 mass %. If it is less than 0.1 mass %, the stabilization effect will not be obtained, and if it is added in excess of 5 mass %, color stripes may occur.

[0025] When polyethylene glycol is added to the composition of the present invention, the effect of stably maintaining salicylic acid is further improved. The polyethylene glycol preferably used in the present invention is a polyethylene glycol having an average molecular weight of 1,000 to 15,000. Specific examples include polyethylene glycol 1000 (INCI name: PEG-20), polyethylene glycol 1500 (INCI name: PEG-6; PEG-32), polyethylene glycol 4000 (INCI name: PEG-75), polyethylene glycol 6000 (INCI name: PEG-150), and polyethylene glycol 11,000 (INCI name: PEG-240). Of these, polyethylene glycol 6000 is preferred.

[0026] The amount of polyethylene glycol to be blended is preferably 1 to 8 mass % relative to the total amount of the composition, more preferably 2 to 7 mass %, and particularly preferably 3 to 6 mass %.

[0027] Other optional components include, for example, moisturizers, UV absorbers, UV scattering agents, buffers, chelating agents, preservatives, fragrances, various drugs, etc., but are not limited to these exemplary components.

[0028] The water-in-oil emulsion composition of the present invention can be prepared by a conventional method, and the emulsification method is not particularly limited. For example, a method can be used in which an aqueous phase (internal phase) and an oil phase (external phase) are separately prepared and heated to about 80°C, the heated aqueous phase is gradually added to the oil phase, emulsified in an emulsifier, and then allowed to cool to room temperature.

[0029] The composition of the present invention stably contains a higher concentration of salicylic acid than conventional compositions, and therefore the anti-acne effect based on salicylic acid is fully exhibited. In addition, the composition contains coloring materials such as pigments, and therefore does not produce color streaks, thereby exhibiting an excellent makeup effect. Therefore, the composition of the present invention is particularly suitable for use as a makeup cosmetic. [Example]

[0030] The present invention will be described in more detail below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0031] Makeup cosmetics having the formulations shown in Table 1 below were prepared in a conventional manner. The cosmetics of each example were evaluated for syneresis stability, color streaks, and usability (immediately after preparation and after 2 weeks) according to the following methods and criteria.

[0032] (1) Separation stability Each cosmetic composition was left to stand at 50°C for 4 weeks, and then visually inspected for syneresis (oil floating) and evaluated according to the following criteria. (Evaluation criteria) A: No change (no syneresis) B: A small amount of transparent liquid was observed on the surface. C: Clear liquid was observed.

[0033] (2) Colored stripes The cosmetic material of each example was stored in a polyethylene container, and the bulk of the cosmetic material was visually observed and evaluated according to the following criteria. (Evaluation criteria) A: No color stripes B: There are blurred color stripes in a small area, but the overall appearance is fine C: Wide, blurred color stripes

[0034] (3) Usability The usability of each cosmetic example was evaluated by a panel of experts according to the following criteria immediately after preparation (immediately after) and after leaving it to stand at room temperature for 2 weeks (after aging). (Evaluation criteria) A: Lightly stretchy B: Slightly heavy stretch C: Very hard to stretch

[0035] [Table 1]

[0036] As shown in Table 1, the cosmetic of Example 1, which is a water-in-oil emulsion composition containing all of (a) salicylic acid, (b) organically modified clay mineral, (c) sorbitan fatty acid ester, and (d) colorant, had excellent syneresis stability, did not produce color streaks, and showed no change in usability over time. On the other hand, Comparative Example 1, in which the sorbitan fatty acid ester was replaced with isostearic acid, showed an increase in viscosity over time, resulting in slightly heavy usability. Comparative Example 2, which did not contain either the sorbitan fatty acid ester or isostearic acid, showed heavy usability immediately after preparation and slight color streaks. Comparative Example 3, in which the salicylic acid was omitted from Comparative Example 2, showed a slight improvement in usability but did not suppress color streaks. Furthermore, Comparative Example 4, in which the salicylic acid in Example 1 was replaced with 4-methoxysalicylic acid, showed an increase in viscosity over time, resulting in slightly heavy usability and significant color streaks. From the above, it was demonstrated that by blending all of the essential components (a) to (d) of the present invention, not only syneresis stability but also color streaks and changes in usability (viscosity increase) can be suppressed.

Claims

1. (a) 0.5% by mass or more of salicylic acid or a salt thereof; (b) organically modified clay minerals; (c) 0.1 to 4.0% by mass of a sorbitan fatty acid ester; (d) 0.1% by weight or more and 40% by weight or less of a colorant; and Polyether-modified silicone, A water-in-oil emulsion composition for anti-acne, comprising:

2. 2. The composition according to claim 1, wherein the amount of the organically modified clay mineral (b) blended is 0.1 to 5.0 mass % based on the total amount of the composition.

3. The composition of claim 1 or 2, further comprising polyethylene glycol.

4. The composition according to claim 1 , wherein the (c) sorbitan fatty acid ester is sorbitan sesquiisostearate.

5. A makeup cosmetic comprising a composition described in any one of claims 1 to 4.

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