Water-in-oil-type emulsion cosmetic

Abstract

The purpose of the present invention is to provide a water-in-oil-type emulsion cosmetic of non-silicone type, which has been difficult to uniformly thicken, that can be uniformly thickened and in which the outflow of a coloring material into an external oily phase can be suppressed. A water-in-oil-type emulsion cosmetic according to the present invention is characterized by comprising a nonionic surfactant (A) having an HLB value of 9 or more, a hydrophobized pigment (B), one or more types of waxes (C) selected from the group consisting of sunflower seed wax, dextrin palmitate, jojoba esters, polyethylene wax, and microcrystalline waxes, and either not containing any silicone oil or containing a silicone oil in an amount of 10 mass% or less with respect to the whole amount of the water-in-oil-type emulsion cosmetic, wherein the hydrophobized pigment (B) is dispersed in an inner aqueous phase.

Description

Water-in-oil emulsion cosmetics

[0001] The present invention relates to a water-in-oil emulsion cosmetic. More specifically, the present invention relates to a water-in-oil emulsion cosmetic that enables uniform thickening in non-silicone water-in-oil emulsion cosmetics, which are difficult to achieve uniformly, and that can also prevent hydrophobized pigments dispersed in the internal aqueous phase from leaking into the external oil phase.

[0002] Water-in-oil emulsion compositions, which have an oil phase as the external phase and an aqueous phase as the internal phase, are suitable for use as external skin preparations because they can efficiently distribute oil-soluble active ingredients, such as emollients, drugs, and ultraviolet absorbers, on the skin, and are widely used in makeup cosmetics such as foundations.

[0003] Makeup cosmetics such as foundations contain white pigments such as zinc oxide and titanium oxide, and color pigments such as iron oxide, which have the effect of correcting uneven skin tone such as age spots and freckles, as well as skin irregularities such as pores. To achieve a high correction effect, it is required to incorporate a large amount of these powders into cosmetics.

[0004] When incorporating powder into a water-in-oil emulsion cosmetic, it is common to disperse the powder, the surface of which has been hydrophobized, in the external oil phase. For example, Patent Document 1 proposes using a mixture of alkyldimethicone copolyol, dimethicone copolyol, a hydrophobically coated pigment, and a large amount of volatile oil to obtain a foundation composition that has excellent storage stability and enables uniform makeup application to the skin. However, dispersing powder in the external oil phase tends to cause a powdery feeling (a feeling of lack of smoothness) when applied to the skin, resulting in a poor feel when used. Furthermore, when the external oil phase contains polymeric components such as solid oils (e.g., wax), semi-solid oils, or film-forming agents, these components and the powder tend to aggregate, resulting in problems such as poor spreadability and uneven finish when applied.

[0005] Therefore, in order to improve the powder squeaking and powder aggregation during application, attempts have been made to disperse powder in the internal aqueous phase. For example, Patent Document 2 proposes thickening or solidifying the external oil phase with wax and disteardimonium hectorite in order to stably disperse and blend powder in the internal aqueous phase.

[0006] Meanwhile, in conventional water-in-oil emulsion cosmetics, silicone oil has been widely used as the liquid oil that constitutes the external oil phase, but in recent years there has been a growing need for "silicone-free" or "silicone-free" cosmetics that do not contain silicone compounds.

[0007] However, when non-silicone water-in-oil emulsion cosmetics are blended with oil phase thickeners that are commonly used in cosmetics, such as disteardimonium hectorite, candelilla wax, and carnauba wax, uneven thickening can occur, preventing the cosmetic from flowing smoothly and uniformly, or the emulsion particles can become unstable, causing powder dispersed in the internal aqueous phase to leak out into the external oil phase.

[0008] JP 2004-026833 A JP 2017-031149 A

[0009] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a water-in-oil emulsion cosmetic that enables uniform thickening in non-silicone water-in-oil emulsion cosmetics, which are difficult to achieve uniformly, and that is also capable of suppressing outflow of hydrophobized pigments dispersed in the internal aqueous phase into the external oil phase.

[0010] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that by preparing an aqueous dispersion in which a hydrophobized pigment is dispersed in an aqueous component using a nonionic surfactant having a specified HLB, emulsifying this aqueous dispersion in an oily component that is substantially free of silicone oil, and then blending in a specified wax, it is possible to achieve uniform thickening, and further, to stably disperse the hydrophobized pigment inside the emulsified particles, i.e., in the internal aqueous phase, thereby significantly suppressing leakage of the hydrophobized pigment into the external oil phase, thereby completing the present invention.

[0011] That is, the gist of the present invention is a water-in-oil emulsion cosmetic comprising: (A) a nonionic surfactant having an HLB of 9 or more; (B) a hydrophobized pigment; and (C) one or more waxes selected from the group consisting of sunflower seed wax, dextrin palmitate, jojoba ester, polyethylene wax, and microcrystalline wax; wherein the cosmetic does not contain silicone oil or the silicone oil content is 10 mass% or less of the total amount of the water-in-oil emulsion cosmetic; and (B) the hydrophobized pigment is dispersed in an internal aqueous phase.

[0012] By adopting the above-described configuration, the water-in-oil emulsion cosmetic according to the present invention enables uniform thickening of the non-silicone water-in-oil emulsion cosmetic, and also inhibits the outflow of the hydrophobized pigment, which is the coloring material, from the internal aqueous phase to the external oil phase, thereby achieving an excellent feel when used.

[0013] The water-in-oil emulsion cosmetic of the present invention contains (A) a nonionic surfactant with an HLB of 9 or more, (B) a hydrophobized pigment, and (C) a specific wax, and is substantially free of silicone oil. This will be explained in detail below. In the following, polyethylene glycol may be abbreviated as "PEG."

[0014] <(A) Nonionic Surfactant> The (A) nonionic surfactant (hereinafter sometimes referred to as "component (A)") blended in the present invention adsorbs to the particle surface of the (B) hydrophobized pigment to hydrophilize it, and has the effect of uniformly dispersing the (B) hydrophobized pigment in the internal aqueous phase. The (A) nonionic surfactant has an HLB of 9 or more, more preferably 12 or more, and even more preferably 14 or more. When the HLB is 9 or more, the (B) hydrophobized pigment can be reliably and satisfactorily dispersed in the aqueous component that constitutes the internal aqueous phase without aggregation.

[0015] Examples of the nonionic surfactant (A) include fatty acid polyoxyalkylene glyceryl, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene alkyl ether, fatty acid polyoxyalkylene sorbitan, polyoxyalkylene phytosterol, and polyoxyalkylene-modified silicone. More specifically, fatty acid polyoxyalkylene glyceryl such as PEG-20 glyceryl isostearate; polyoxyalkylene hydrogenated castor oils such as PEG-40 hydrogenated castor oil, PEG-60 hydrogenated castor oil, PEG-100 hydrogenated castor oil; polyoxyalkylene alkyl ethers such as PEG-20 oleyl ether, PEG-10 behenyl ether, PEG-20 behenyl ether, PEG-30 behenyl ether; fatty acid polyoxyalkylene sorbitan such as PEG-20 sorbitan monolaurate, PEG-20 sorbitan monostearate, PEG-20 sorbitan monooleate; polyoxyalkylene phytosterol such as PEG-30 phytosterol; polyoxyalkylene-modified silicones such as PEG-12 dimethicone; and the like. Of these, PEG-60 hydrogenated castor oil and PEG-100 hydrogenated castor oil are preferred.

[0016] One or more types of (A) nonionic surfactants can be used, and the total content thereof is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.75% by mass or more, relative to the total amount of the water-in-oil emulsion cosmetic, and is preferably 2% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass or less. Therefore, the content range can be 0.3 to 2% by mass, 0.5 to 1.5% by mass, or 0.75 to 1.0% by mass, etc.

[0017] <(B) Hydrophobized Pigment> The (B) hydrophobized pigment (hereinafter sometimes referred to as "component (B)") blended in the present invention can be a colorant that is typically blended in cosmetics, and is not particularly limited. The (B) hydrophobized pigment is a powder in which the surface of a powder made of a base such as titanium oxide, iron oxide, magnesium oxide, zinc oxide, calcium oxide, calcium phosphate, calcium carbonate, alumina, aluminum hydroxide, barium sulfate, pearlescent pigments (e.g., titanium mica, bismuth oxychloride), and talc, or a composite material of these bases, has been hydrophobized.

[0018] Examples of hydrophobic treatments include silicone treatments (treatments with silicone oils such as methylhydrogenpolysiloxane, dimethylpolysiloxane, and methylphenylpolysiloxane; alkylsilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, and octyltrimethoxysilane; and fluoroalkylsilanes such as trifluoromethylethyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane), fatty acid treatments (treatments with palmitic acid, isostearic acid, stearic acid, lauric acid, myristic acid, behenic acid, oleic acid, rosin acid, and 12-hydroxystearic acid), fatty acid soap treatments (treatments with aluminum stearate, calcium stearate, and 12-hydroxystearic acid), fatty acid ester treatments (treatments with dextrin fatty acid esters, cholesterol fatty acid esters, sucrose fatty acid esters, and starch fatty acid esters), and amino acid treatments (treatments with dilauramidoglutamide lysine Na and polyglyceryl-2 tetraisostearate). These hydrophobic treatments can be carried out in accordance with conventional methods.

[0019] The average particle size of the hydrophobic treated pigment (B) is preferably 200 to 10,000 nm, and more preferably 200 to 1,000 nm. Note that the "average particle size" in this specification is the number-average size (average of 50 random particles) determined by image analysis of a transmission electron microscope photograph.

[0020] One or more types of (B) hydrophobized pigments can be used, and the total content thereof is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, relative to the total amount of the water-in-oil emulsion cosmetic. It is also preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. Therefore, examples of the content range include 3 to 25% by mass, 5 to 20% by mass, and 7 to 15% by mass.

[0021] <(C) Wax> The wax (C) (hereinafter sometimes referred to as "component (C)") blended in the present invention is a specific wax widely used as an oil phase thickener in cosmetics, namely, one or more waxes selected from the group consisting of sunflower seed wax, dextrin palmitate, jojoba ester, polyethylene wax, and microcrystalline wax. Sunflower seed wax is a natural wax obtained from sunflower seeds and is a C42 to C62 monoester composed of a long-chain alcohol and a long-chain fatty acid. Jojoba ester is a complex ester mixture derived from jojoba seed oil and hydrogenated jojoba oil. Dextrin palmitate is an ester (dextrin fatty acid ester) obtained by dehydration condensation of the hydroxy group of dextrin with the carboxy group of palmitic acid. Polyethylene wax is a low-molecular-weight ethylene polymer that exhibits a white wax-like solid. In the present invention, waxes with a molecular weight of 300 to 700, particularly 400 to 600, are preferably used. Microcrystalline wax is a hydrocarbon wax that is separated and refined from petroleum and remains solid at room temperature. In the present invention, those having a molecular weight of 450 to 1000, particularly 500 to 800, are preferably used.

[0022] One or more types of wax (C) can be used, and the total content thereof is preferably 0.5% by mass or more, more preferably 0.75% by mass or more, and even more preferably 1.0% by mass or more, relative to the total amount of the water-in-oil emulsion cosmetic. It is also preferably 3% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2.0% by mass or less. Therefore, examples of the content range include 0.5 to 3% by mass, 0.75 to 2.5% by mass, and 1.0 to 2.0% by mass.

[0023] The water-in-oil emulsion cosmetic of the present invention is a "silicone-free" cosmetic that does not substantially contain silicone oil. However, a trace amount of silicone oil may be contained as long as it does not impair the effects of the present invention. If silicone oil is contained, it is preferably at most 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, of the total amount of the water-in-oil emulsion cosmetic.

[0024] In this specification, "silicone oil" refers to an organopolysiloxane having a siloxane (-Si-O-Si-) structure as the main skeleton in the molecule and organic groups on the side chains. Specific examples of silicone oils include linear polysiloxanes such as dimethylpolysiloxane (dimethicone), methylphenylpolysiloxane, and diphenylpolysiloxane; cyclic polysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; and alkyl-modified polysiloxanes such as caprylyl methicone.

[0025] <Optional Components> In addition to the above components (A) to (C), the water-in-oil emulsion cosmetic of the present invention can contain components that are commonly used in water-in-oil emulsion cosmetics, as long as the effects of the present invention are not impaired. For example, oily components, aqueous components, alcohols, surfactants, moisturizers, stabilizers, chelating agents, preservatives, fragrances, etc. may be appropriately blended as needed.

[0026] <Production Method> The water-in-oil emulsion cosmetic of the present invention is characterized by containing (B) a hydrophobized pigment in its internal aqueous phase. To disperse (B) the hydrophobized pigment in the internal aqueous phase, it is first necessary to prepare an aqueous dispersion in which (B) the hydrophobized pigment is dispersed in the aqueous components by mixing (A) a nonionic surfactant, (B) the hydrophobized pigment, and other aqueous components and processing the mixture using a bead mill, high-pressure homogenizer, or the like. Next, the obtained aqueous dispersion is emulsified in an oil phase mixture obtained by mixing (C) wax and other oily components using a method similar to that used for producing general water-in-oil emulsion cosmetics.

[0027] <Water-in-oil emulsion cosmetic> The water-in-oil emulsion cosmetic according to the present invention is preferably in a form other than a solid, and is particularly preferably in a liquid or cream form. The viscosity of the water-in-oil emulsion cosmetic according to the present invention at 25°C is preferably 2000 mPa·s or more, more preferably 3000 mPa·s or more, and even more preferably 4000 mPa·s or more. It is also preferably 20000 mPa·s or less, more preferably 7000 mPa·s or less, and even more preferably 5000 mPa·s or less. Specific viscosity ranges include 2000 to 20000 mPa·s, 3000 to 7000 mPa·s, and 4000 to 5000 mPa·s. In this specification, "viscosity" refers to a value measured using a Brookfield viscometer (rotor No. 4, rotation speed 12 rpm, 1 minute).

[0028] The water-in-oil emulsion cosmetic of the present invention stably contains the hydrophobized pigment (B) in the internal aqueous phase, so it is less likely to feel powdery when applied to the skin and has excellent spreadability. Furthermore, because the hydrophobized pigment is dispersed in the internal aqueous phase, it is less susceptible to the effects of solid oils and the like, and aggregation of the hydrophobized pigments is less likely to occur, making it possible to achieve a uniform makeup finish. Therefore, to maximize these effects, it is preferable that the water-in-oil emulsion cosmetic of the present invention contains substantially no powder in the external oil phase, and even more preferably, it contains no powder at all in the external oil phase.

[0029] The water-in-oil emulsion cosmetic of the present invention can contain a sufficient amount of (B) hydrophobized pigment in the internal aqueous phase, i.e., within the emulsion particles, and therefore has an excellent skin irregularity correcting effect, naturally blurring and making less noticeable fine wrinkles, pores, and other irregularities on the skin, while also providing excellent spreadability upon application and uniformity in the makeup finish. Therefore, the cosmetic can be widely used in makeup cosmetics such as foundations, concealers, makeup bases, eye shadows, blushes, and mascaras.

[0030] The present invention will be described in further detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, the contents are expressed in mass % relative to the total amount of the water-in-oil emulsion cosmetic.

[0031] Examples 1 to 6 and Comparative Examples 1 to 6 Water-in-oil emulsion cosmetics having the compositions shown in Tables 1 and 2 below were prepared, and the viscosity, dispersion stability of coloring material, and thickening uniformity were evaluated by the following methods.

[0032] (1) Viscosity The viscosity of the adjusted water-in-oil emulsion cosmetic at 25°C was measured using a Brookfield viscometer with a rotor No. 4 at a rotation speed of 12 rpm for 1 minute.

[0033] (2) Dispersion stability of colorant The dispersion state of the hydrophobic treated pigment (colorant) was observed using an optical microscope (400x magnification) immediately after the prepared water-in-oil emulsion cosmetic was placed in a cylindrical container and after it was left to stand at room temperature (25-30°C) for one day, and was evaluated according to the following criteria. <Evaluation criteria> A+: There is no change in the dispersion state of the hydrophobic treated pigment before and after it is left to stand, and no outflow of the hydrophobic treated pigment into the external oil phase is observed. A: After it is left to stand, slight uneven distribution of the hydrophobic treated pigment is observed in the internal aqueous phase, but no outflow of the hydrophobic treated pigment into the external oil phase is observed. B: A slight outflow of the hydrophobic treated pigment into the external oil phase is observed, but it is at a fully acceptable level. C: Outflow of the hydrophobic treated pigment into the external oil phase is observed.

[0034] (3) Thickening Uniformity The prepared water-in-oil emulsion cosmetic was placed in a cylindrical container, and visually observed to determine whether the water-in-oil emulsion cosmetic was uniformly thickened, i.e., whether there was no unevenness in the thickening and whether the cosmetic flowed smoothly and uniformly when the container was tilted, and evaluated according to the following criteria. <Evaluation criteria> A: There was no unevenness in the thickening, and the cosmetic flowed smoothly and uniformly. B: There was slight unevenness in the thickening, but the cosmetic flowed smoothly and uniformly. C: There was unevenness in the thickening, and the cosmetic did not flow smoothly and uniformly.

[0035]

[0036]

[0037] *1 Vegelight C912LC (Grant Industries, Inc.) *2 PA Wax (Nikko Rica Corporation) *3 Oil Chemistry (Lubrizol Advanced Materials, Inc.)

[0038] As shown in Tables 1 and 2, when sunflower seed wax, dextrin palmitate, jojoba ester, and a mixture of polyethylene wax and microcrystalline wax were used as the (C) wax, excellent results were obtained in terms of colorant dispersion stability and thickening uniformity (Examples 1 to 6). In particular, when sunflower seed wax was used, extremely excellent evaluation results were obtained (Examples 1, 2, and 6). It was also confirmed that excellent evaluation results were obtained when an oil phase thickener other than the (C) wax was contained in an amount that did not interfere with the effects of the present invention (Comparison between Examples 1 and 2), or when the hydrophobic treatment agent applied to the (B) hydrophobic-treated pigment was changed (Comparison between Examples 1 and 6).

[0039] On the other hand, when glyceryl behenate / eicosanedioate, polyurethane-79, hydroxystearic acid, candelilla wax, carnauba wax, or disteardimonium hectorite, which are widely used as oil phase thickeners in cosmetics, were used instead of the (C) wax, insufficient results were observed in either or both of the dispersion stability and thickening uniformity of the colorant (Comparative Examples 1 to 6). Note that in Comparative Examples 2, 3, and 5, the viscosity was too low to be measured correctly, so the viscosity column was marked with "-".

Claims

1. A water-in-oil emulsion cosmetic comprising: (A) a nonionic surfactant with an HLB of 9 or more; (B) a hydrophobized pigment; and (C) one or more waxes selected from the group consisting of sunflower seed wax, dextrin palmitate, jojoba ester, polyethylene wax, and microcrystalline wax; wherein the cosmetic does not contain silicone oil or the silicone oil content is 10 mass% or less of the total amount of the water-in-oil emulsion cosmetic; and (B) the hydrophobized pigment is dispersed in the internal aqueous phase.

2. The water-in-oil emulsion cosmetic according to claim 1, wherein the wax (C) is sunflower seed wax.

3. The water-in-oil emulsion cosmetic according to claim 1, wherein the content of (C) wax is 0.5 to 3 mass% based on the total amount of the water-in-oil emulsion cosmetic.

4. A water-in-oil emulsion cosmetic according to claim 1, wherein (B) the hydrophobized pigment has been hydrophobized by amino acid treatment.

5. The water-in-oil emulsion cosmetic according to claim 1, wherein the outer oil phase of the water-in-oil emulsion cosmetic is substantially free of powder.

6. The water-in-oil emulsion cosmetic according to claim 1, wherein the water-in-oil emulsion cosmetic is in a liquid form.

7. The water-in-oil emulsion cosmetic according to claim 1, wherein the viscosity of the water-in-oil emulsion cosmetic at 25°C is 2,000 to 20,000 mPa·s.

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