Oil-in-water emulsion cosmetic

Abstract

To provide an oil-in-water emulsion cosmetic, which is an oil-in-water emulsion composition having a high internal oil phase with a high content of oil and particulate metal oxide, while delivering superior usability and favorable emulsion stability.SOLUTION: An oil-in-water emulsion cosmetic comprising polyvinyl alcohol having a saponification degree of 65 to 97 mol%, hydrophobically treated particulate metal oxide, and a polyhydric alcohol, wherein the oil phase ratio is 66 mass% to 79 mass%, and the content of the polyhydric alcohol is 5 mass% to 15 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oil-in-water emulsion cosmetic. [Background technology]

[0002] In general, sunscreen cosmetics contain fine metal oxide powders to achieve a high SPF (Sun Protection Factor). It is widely known that these fine metal oxide particles have a strong ultraviolet shielding effect. Because the content of fine metal oxide particles (e.g., titanium oxide, zinc oxide, cerium oxide) in sunscreen cosmetics tends to be relatively large, two or more types of fine metal oxide particles may be used in combination, such as a combination of titanium oxide and zinc oxide, or, depending on the product, an organic ultraviolet absorber may also be used in combination.

[0003] When such fine metal oxide particles are incorporated into sunscreen cosmetics in the form of an oil-in-water emulsion composition, hydrophobically treated fine metal oxide particles are often incorporated to enhance their dispersibility in the oil phase. At the same time, attempts have been made to enhance the dispersibility of the hydrophobically treated fine metal oxide particles using surfactants and the like. However, when a large amount of surfactant is used in an oil-in-water emulsion composition for emulsification or dispersion, problems such as stickiness and irritation can occur when the composition is directly applied to the human body, such as the skin. In addition, many consumers are concerned about the effects of surfactants that can be absorbed by the human body. For this reason, it is desirable to minimize the amount of surfactant used in oil-in-water emulsion compositions used as sunscreen cosmetics.

[0004] As mentioned above, there has been a certain demand for emulsion compositions that do not use surfactants. Patent Document 1, for example, discloses an oil-in-water emulsion composition that contains a light-shielding powder and is stabilized by a surface-charged emulsified powder, as an example of an oil-in-water emulsion composition that is used as a sunscreen cosmetic and that does not substantially contain a surfactant as an emulsifier. The oil-in-water emulsion composition described in Patent Document 1 is said to have excellent resistance to aqueous solutions containing ions, and is said to maintain or improve its light-shielding effect after contact with the aqueous solution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-050627 Summary of the Invention [Problem to be solved by the invention]

[0006] However, it has been pointed out that sunscreen cosmetics such as the oil-in-water emulsion composition described in Patent Document 1 do not substantially contain surfactants as emulsifiers, making it difficult to incorporate high amounts of oil agents or fine particle metal oxides, and therefore do not provide sufficient UV blocking effects. Therefore, the present invention has been made in consideration of the above problems, and aims to provide an oil-in-water emulsion cosmetic that is an oil-in-water emulsion composition with a high internal oil phase that incorporates a high amount of oil agents and fine particle metal oxides, yet has an excellent feel when used and good emulsion stability. [Means for solving the problem]

[0007] The means for solving the problems of the present invention are as follows. 1. A composition comprising polyvinyl alcohol having a saponification degree of 65 to 97 mol%, hydrophobized metal oxide fine particles, and polyhydric alcohol; The oil phase ratio is 66 to 79% by mass, The oil-in-water emulsion cosmetic is characterized in that the content of the polyhydric alcohol is 5 to 15% by mass. 2. The oil-in-water emulsion cosmetic according to 1, wherein the content of the hydrophobized metal oxide particles is 5 to 35% by mass. 3. The oil-in-water emulsion cosmetic according to 1. or 2., wherein the viscosity of the polyvinyl alcohol measured with a Brookfield viscometer (4% aqueous solution, 20°C) is 20 mPa·s or less. 4. The oil-in-water emulsion cosmetic according to any one of 1. to 3., wherein the polyhydric alcohol includes one or more of BG, glycerin, and diglycerin. [Effects of the Invention]

[0008] The oil-in-water emulsion cosmetic of the present invention has an excellent feel when used and good emulsion stability. DETAILED DESCRIPTION OF THE INVENTION

[0009] The oil-in-water emulsion cosmetic of the present invention (hereinafter also referred to as cosmetic) contains polyvinyl alcohol having a saponification degree of 65 to 97 mol%, hydrophobized metal oxide fine particles, and polyhydric alcohol, The oil phase ratio is 66 to 79% by mass, It contains 5 to 15 mass % of polyhydric alcohol. In this specification, the expression "A to B" (A and B are numerical values ​​or ratios) means a numerical range that includes both ends.

[0010] Polyvinyl alcohol with a saponification degree of 65 to 97 mol% The cosmetic of the present invention contains polyvinyl alcohol (hereinafter, polyvinyl alcohol will also be referred to as PVA) having a degree of saponification of 65 to 97 mol%. By containing PVA having a degree of saponification of 65 to 97 mol%, the cosmetic of the present invention can be emulsified into an oil-in-water type and also has excellent emulsion stability. The degree of saponification of the PVA contained in the oil-in-water emulsion cosmetic of the present invention is not particularly limited as long as the effects of the present invention are achieved, but it can be 90 mol% or less, 81 mol% or less, 74 mol% or less, etc. Furthermore, the cosmetic of the present invention can contain two or more types of PVA having a degree of saponification of 65 to 97 mol% that differ in degree of saponification or degree of polymerization.

[0011] From the viewpoint of emulsion stability, the viscosity of the PVA used in the present invention, as measured with a Brookfield viscometer (4% aqueous solution, 20°C), is preferably 20 mPa·s or less. The viscosity of the PVA used in the present invention is more preferably 15 mPa·s or less, even more preferably 10 mPa·s or less, and even more preferably 8 mPa·s or less. When two or more PVAs are used, it is preferable that the viscosity of a 4% solids aqueous solution mixed at the blending ratio, as measured with a Brookfield viscometer, is within the above-mentioned range.

[0012] From the viewpoint of emulsifiability and emulsion stability, the cosmetic of the present invention preferably contains 0.1% by mass or more and 5% by mass or less of PVA having a degree of saponification of 65 to 97% by mole relative to the entire cosmetic. The content of this PVA relative to the entire cosmetic is more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0013] Hydrophobic treated metal oxide particles The cosmetic of the present invention contains hydrophobized metal oxide fine particles. The hydrophobized metal oxide fine particles are blended for the purpose of scattering or blocking ultraviolet rays, and the surface is made hydrophobic by surface treatment (coating treatment) with fatty acid, silicone, or the like. Examples of metal oxides used in the hydrophobic treated metal oxide fine particles include titanium oxide, zinc oxide, cerium oxide, and zirconium oxide, with titanium oxide and zinc oxide being particularly preferred. The metal oxide used for the hydrophobized metal oxide fine particle preferably has an average particle size (median diameter) of 1 nm to 100 nm for its primary particles. If the average particle size of the primary particles is larger than 100 nm, the particles will scatter visible light more, which may reduce the transmittance of visible light, i.e., transparency. On the other hand, if the average particle size of the primary particles is smaller than 1 nm, the ultraviolet blocking effect may be reduced. The average particle size of the primary particles is more preferably 5 nm or more, and more preferably 50 nm or less.

[0014] The type of hydrophobic treatment agent used in the hydrophobized metal oxide microparticles is not limited, and examples thereof include fatty acids, higher fatty acids, higher alcohols, hydrocarbons, triglycerides, esters, silicone oils, silicone resins, fluorine compounds, acylamino acids, etc. The hydrophobized metal oxide microparticles used in the oil-in-water emulsion cosmetic of this embodiment may be a commercially available paste-like product in which the metal oxide is stably reduced to low-order particles in a volatile silicone base. Examples of such commercially available paste-like products include "FLT-01" manufactured by Teika Corporation (titanium oxide, aluminum hydroxide, hydrated silica, dimethicone, hydrogen dimethicone, trimethylsiloxysilicate, cyclopentasiloxane), "SA-UT-A40 / D5 (50%) MiBrid Dispersion" manufactured by Miyoshi Chemicals Co., Ltd. (titanium oxide, aluminum hydroxide, stearic acid, dimethicone, cyclopentasiloxane), "MiyoSCREEN UT-01 / D5" manufactured by Miyoshi Chemicals Co., Ltd. (titanium oxide, aluminum hydroxide, stearic acid, dimethicone, cyclopentasiloxane), and "MiyoSCREEN UZ-01 / D5" manufactured by Miyoshi Chemicals Co., Ltd. (zinc oxide, dimethicone, methicone, myristic acid, cyclopentasiloxane). As the hydrophobic treated fine particle metal oxide, two or more kinds of metal oxides differing in metal species, primary particle size, hydrophobic treatment agent, etc. may be used.

[0015] The content of the hydrophobic treated metal oxide particles in the cosmetic of the present invention depends on the target SPF value, but is preferably 5% by mass or more and 35% by mass or less from the viewpoint of emulsifiability and emulsion stability. The content of the hydrophobic treated metal oxide particles relative to the total cosmetic is more preferably 6% by mass or more, even more preferably 7% by mass or more, more preferably 30% by mass or less, and even more preferably 25% by mass or less. In the cosmetic of the present invention, the mass ratio of the hydrophobized metal oxide fine particle to the PVA having a degree of saponification of 65 to 97 mol% (hydrophobized metal oxide fine particle / PVA) is preferably 5 to 100, more preferably 10 to 50, from the viewpoints of emulsifiability and emulsion stability.

[0016] Polyhydric alcohol The cosmetic of the present invention contains 5 to 15 mass % of a polyhydric alcohol based on the total mass of the cosmetic, which provides excellent emulsifiability and emulsion stability. In this specification, polyhydric alcohol refers to an organic compound having 10 or less carbon atoms and two or more hydroxyl groups. The polyhydric alcohol used in the present invention is not particularly limited and can be any polyhydric alcohol that is formulated into cosmetics, as long as it achieves the effects of the present invention, and examples include ethylene glycol, 1,3-butylene glycol (BG), propylene glycol, dipropylene glycol (DPG), pentylene glycol, butylethylpropanediol, glycerin, diglycerin, etc., and these can be used alone or in combination of two or more. Of these, BG, glycerin, and diglycerin are preferred from the standpoint of emulsifying ability and emulsion stability.

[0017] The cosmetic of the present invention contains 5 to 15% by mass of polyhydric alcohol relative to the total cosmetic. The content of polyhydric alcohol relative to the total cosmetic is preferably 6% by mass or more, even more preferably 7% by mass or more, more preferably 13% by mass or less, and even more preferably 11% by mass or less. In the cosmetic of the present invention, the mass ratio of the polyhydric alcohol to the PVA having a degree of saponification of 65 to 97 mol% (polyhydric alcohol / PVA) is preferably 5 to 30 from the viewpoints of emulsifiability and emulsion stability.

[0018] "Oil phase" The cosmetic of the present invention has an oil phase ratio of 66 to 79% by mass, which is composed of hydrophobized metal oxide particles, oils, and other oil-soluble substances, and is therefore relatively high for an oil-in-water emulsion cosmetic. The cosmetic of the present invention contains polyvinyl alcohol having a degree of saponification of 65 to 97 mol%, hydrophobized metal oxide particles, and a polyhydric alcohol. By including 5 to 15% by mass of the polyhydric alcohol, the cosmetic can emulsify despite having a high internal oil phase and exhibits excellent emulsion stability. The oil phase ratio of the cosmetic of the present invention is preferably 68% by mass or more, more preferably 69% by mass or more, and preferably 78% by mass or less, more preferably 77% by mass or less, and even more preferably 76% by mass or less.

[0019] The oil-in-water emulsion cosmetic of the present invention contains an oil. The content of the oil in the oil-in-water emulsion cosmetic of the present invention is preferably 35% by mass or more and 70% by mass or less. By having the oil content within the above range, it is possible to improve the feel of the oil-in-water emulsion cosmetic while maintaining sufficient emulsion stability. The content of the oil is more preferably 40% by mass or more, even more preferably 45% by mass or more, and more preferably 65% ​​by mass or less, even more preferably 60% by mass or less.

[0020] The oil agent is not particularly limited in terms of its properties or type, as long as it is one that is commonly used in cosmetics and the like. However, from the viewpoints of emulsion stability and usability, it is preferable that the oil agent be one or more oils selected from hydrocarbon oils, silicone oils, and ester oils. Examples of hydrocarbon oils include liquid paraffin, squalene, and squalane.

[0021] Examples of ester oils include cetyl ethylhexanoate, 1,3-butylene glycol diisononanoate, 1,3-butylene glycol di-2-ethylhexanoate, dipropylene glycol diisononanoate, dipropylene glycol di-2-ethylhexanoate, isononyl isononanoate, neopentyl glycol dicaprate, ethylhexyl palmitate, isostearyl neopentanoate, di(phytosteryl / octyldodecyl) lauroyl glutamate, pentaerythritol tetra-2-ethylhexanoate, di(isostearyl / phytosteryl) dimer dilinoleate, and jojoba oil. Examples of silicone oils include linear polysiloxanes such as dimethylpolysiloxane and methylphenylpolysiloxane, and cyclic polysiloxanes such as decamethylcyclopentasiloxane. Among these, silicone oil is preferred in terms of feel when used.

[0022] The oil-in-water emulsion cosmetic of the present invention may contain, to the extent that the effects of the present invention are not impaired, known ingredients that can be incorporated into oil-in-water emulsion cosmetics, such as surfactants, powders other than hydrophobized fine metal oxide particles, higher fatty acids, higher alcohols, silicone-based thickeners, sugars, water-soluble polymers other than PVA with a saponification degree of 65 to 97 mol%, other thickeners, preservatives, sequestering agents, UV absorbers, moisturizers such as hyaluronic acid, fragrances, pH adjusters, etc. Furthermore, the cosmetic may contain other medicinal or physiologically active ingredients, such as vitamins, skin activators, blood circulation promoters, resident flora control agents, active oxygen scavengers, anti-inflammatory agents, whitening agents, and disinfectants.

[0023] Any surfactant may be used as long as the emulsion is an oil-in-water type, and nonionic surfactants, anionic surfactants, amphoteric surfactants, etc. can be blended in. However, since the cosmetic of the present invention can be stably emulsified without blending a surfactant, the content of surfactant in the entire cosmetic is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and most preferably zero (0% by mass). In order to reduce stickiness, the cosmetic of the present invention preferably contains oil-soluble substances (solid oils, higher alcohols, etc.) that are solid or pasty at room temperature relative to the total cosmetic content of the cosmetic, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and most preferably none (0% by mass).

[0024] The oil-in-water emulsion cosmetic of the present invention can be suitably used as a sunscreen, makeup base, foundation, etc. Because the oil-in-water emulsion cosmetic of the present invention is an oil-in-water type, it spreads easily on application, blends well with the skin, is less sticky, and has an excellent feel when used. In the cosmetic of the present invention, the hydrophobized metal oxide microparticles are dispersed in an oil phase. The cosmetic of the present invention has a high internal oil phase, and the region where water evaporates after application to the skin is narrow, and the region where the hydrophobized metal oxide microparticles are not present (region where water evaporates) is also narrow, so a higher SPF can be expected. [Example]

[0025] 1.Raw materials The PVA used was the following raw material manufactured by Mitsubishi Chemical Corporation. [Table 1]

[0026] 2. Preparation method An aqueous phase composition was obtained by uniformly mixing water, PVA, and polyhydric alcohol as aqueous components in the formulation (values ​​are mass %) shown in Table 2. Separately, an oil phase composition was obtained by uniformly mixing a hydrophobized titanium dioxide fine particle dispersion (product name: MiyoSCREEN UT-01 / D5, manufactured by Miyoshi Chemicals Co., Ltd.) and cyclopentasiloxane (product name: KF-995, manufactured by Shin-Etsu Chemical Co., Ltd.) in the formulation (values ​​are mass %) shown in Table 2. The oil phase composition was then added to the aqueous phase composition, and the mixture was stirred at 4,500 rpm for 1 minute using a homomixer at room temperature to obtain a cosmetic preparation.

[0027] 3. Evaluation The prepared cosmetics were evaluated as follows, and the results are shown in Table 2. ·Emulsifying property The appearance of the cosmetic material prepared above was observed 1 minute after stirring was completed, and evaluated according to the following criteria. 〇: Can be emulsified. ×: Separation occurs and emulsification is not possible.

[0028] The cosmetics that were evaluated as having good emulsifying properties were evaluated as follows. The results are shown in Table 2. ·Emulsion stability The emulsified oil-in-water emulsion cosmetic was left to stand in a thermostatic bath set at 50°C. 〇: No change in appearance after 1 month. △: There is no change in appearance after one week, but after one month, separation occurs and an oily layer is formed. ×: Separation occurs after one week, forming an oily layer.

[0029] - Feel (stretchiness, skin compatibility) Approximately 50 mg of the oil-in-water emulsion cosmetic was placed on the inside of the forearm and spread in a circular motion with the pad of a finger within an area of ​​approximately 30 x 30 mm. The spreadability and compatibility with the skin upon application were evaluated by a panel of three experts according to the following criteria. Good: Both spreadability and compatibility with the skin are good. △: Either spreadability or compatibility with skin is good. ×: Both spreadability and compatibility with the skin are poor.

[0030] [Table 2]

[0031] As can be seen from Examples 1 to 19, the oil-in-water emulsion cosmetics of the present invention, by satisfying specific formulations, were excellent in emulsifiability and emulsion stability despite having a high internal oil phase, and also had an excellent feel when used. Comparative Examples 1 to 3 confirmed that an oil phase ratio of 66 to 79% by mass contributes to emulsifiability and emulsion stability. Comparative Examples 4 to 6 confirmed that including 5 to 15% by mass of polyhydric alcohol resulted in excellent emulsion stability. Examples 3, 16 to 19 and Comparative Example 7 confirmed that an oil-in-water emulsion cosmetic can be obtained by setting the degree of saponification of polyvinyl alcohol to 65 to 97% by mole.

Claims

1. The composition contains polyvinyl alcohol having a saponification degree of 65 to 97 mol%, hydrophobized metal oxide fine particles, and polyhydric alcohol, The oil phase ratio is 66 to 79% by mass, The oil-in-water emulsion cosmetic is characterized in that the content of the polyhydric alcohol is 5 to 15% by mass.

2. 2. The oil-in-water emulsion cosmetic according to claim 1, wherein the content of the hydrophobic treated metal oxide particles is 5 to 35% by mass.

3. 3. The oil-in-water emulsion cosmetic according to claim 1, wherein the viscosity of the polyvinyl alcohol measured with a Brookfield viscometer (4% aqueous solution, 20°C) is 20 mPa·s or less.

4. 3. The oil-in-water emulsion cosmetic according to claim 1, wherein the polyhydric alcohol comprises one or more of BG, glycerin, and diglycerin.

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