Water-in-oil type cosmetics

Abstract

To provide a water-in-oil cosmetic that offers both excellent usability as a cosmetic product and high stability. [Solution] A water-in-oil cosmetic composition containing 50% by mass or more of water, comprising the following components (A) to (C): (A) dipolyhydroxy fatty acid polyalkylene glycol, (B) sesquiisostearate sorbitan, and (C) oil thickener. Preferably, component (A) is polyethylene glycol dipolyhydroxystearate, component (B) is sorbitan sesquiisostearate, and component (C) is dextrin palmitate.

Description

Technical Field

[0001] The present invention relates to an oil-in-water cosmetic used as an ultraviolet protection agent, a base cosmetic (makeup base), a foundation, a basic emulsion, a beauty essence, and the like.

Background Art

[0002] Oil-in-water cosmetics are widely used in applications such as ultraviolet protection agents, makeup bases, foundations, etc. that require long-lasting makeup due to their high water resistance. However, oil-in-water cosmetics have a sticky feeling in terms of use because the external phase is an oil phase. On the other hand, if the amount of the internal water phase is increased to suppress stickiness, the viscosity increases or it becomes difficult to maintain emulsion stability. To overcome such problems peculiar to oil-in-water cosmetics, various improvements have been made to the liquid components of oil-in-water cosmetics.

[0003] For example, as a conventional oil-in-water cosmetic, there is one containing diglycerin fatty acid ester and polyglycerin fatty acid ester as oily components, and glycerin and water as aqueous components (see Patent Document 1). The oil-in-water cosmetic described in Patent Document 1 is a high water content type containing 75% by weight or more of water, and contains two kinds of glycerin fatty acid esters with different HLB values in a predetermined ratio to enhance the usability and stability as a cosmetic.

[0004] Also, as another conventional oil-in-water cosmetic, there is one containing PEG-30 dipolyhydroxystearate and ester oil as oily components, and diglycerin and water as aqueous components (see Patent Document 2). The oil-in-water cosmetic described in Patent Document 2 sets the water content within a predetermined range with respect to the total amount of the water phase to obtain good usability while ensuring storage stability as a cosmetic.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, the water-in-oil cosmetic described in Patent Document 1 contains a large amount of diglycerin fatty acid esters with an HLB value of 5.0 or less. Therefore, when actually prepared as a skincare cream, it becomes a highly viscous cream and is not evaluated as having the refreshing feel or light spreadability when applied to the skin. Furthermore, since the water-in-oil cosmetic described in Patent Document 1 attempts to retain a large amount of water in the oil phase using only polyglycerin fatty acid esters without using surfactants such as polyoxyalkylene derivatives, there is a risk that the liquid component may separate in environments with large temperature fluctuations or in situations where temperature changes are repeated.

[0007] The water-in-oil cosmetic described in Patent Document 2 attempts to improve the properties of the cosmetic by using PEG-30 dipolyhydroxystearate as the oily component and further using an ester oil that is semi-solid at 25°C. However, the water content relative to the total amount of the aqueous phase and thus the total amount of the cosmetic is low. Therefore, the water-in-oil cosmetic described in Patent Document 2 is not evaluated as providing a refreshing feeling or light spreadability when applied to the skin.

[0008] This invention has been made in view of the above-mentioned problems, and aims to provide a water-in-oil cosmetic that can achieve both excellent usability as a cosmetic and high stability. [Means for solving the problem]

[0009] The characteristic configuration of the water-in-oil cosmetic composition according to the present invention, which solves the above problems, is as follows: A water-in-oil cosmetic composition containing 50% by mass or more of water, The following components (A) to (C): (A) Dipolyhydroxy fatty acid polyalkylene glycol (B) Sorbitan sesquicate (C) Oil thickener The purpose is to include it.

[0010] According to this water-in-oil cosmetic composition, by including (A) dipolyhydroxy fatty acid polyalkylene glycol, (B) sesquicarbonate sorbitan, and (C) an oil thickener, it is possible to create a water-in-oil cosmetic that is a high-water-content type containing 50% or more water, yet possesses excellent usability in terms of "freshness," "lightness of spreadability," and "skin compatibility," as well as high stability in which the liquid components are less likely to separate.

[0011] In the water-in-oil cosmetic composition of the present invention, The aforementioned component (A) is preferably polyethylene glycol dipolyhydroxystearate.

[0012] In this water-in-oil cosmetic composition, by using polyethylene glycol dipolyhydroxystearate as component (A), it works in cooperation with sorbitan sesquicate, which is component (B), to disperse the aqueous component as fine emulsion particles within the oily component, thereby improving both the feel and stability of the cosmetic.

[0013] In the water-in-oil cosmetic composition of the present invention, The aforementioned component (B) is preferably sorbitan sesquiisostearate.

[0014] With this water-in-oil cosmetic composition, by using sorbitan sesquiisostearate as component (B), it works in cooperation with component (A), dipolyhydroxy fatty acid polyalkylene glycol, to disperse the aqueous component as fine emulsion particles within the oily component, thereby improving both the feel and stability of the cosmetic.

[0015] In the water-in-oil cosmetic composition of the present invention, The aforementioned component (C) is preferably dextrin palmitate.

[0016] According to the water-in-oil type cosmetic of this composition, by using dextrin palmitate as the component (C), especially, while suppressing the stickiness when the cosmetic is applied to the skin, the moist feeling is improved, so that it is possible to improve the usability as a cosmetic such as "freshness", "lightness of stretch", and "skin compatibility".

[0017] In the water-in-oil type cosmetic of the present invention, it is preferable to further contain (D) powder.

[0018] According to the water-in-oil type cosmetic of this composition, by further containing (D) powder, it is particularly possible to apply it to a sunscreen, a base cosmetic, and a foundation.

[0019] In the water-in-oil type cosmetic of the present invention, the viscosity V0 of the prepared water-in-oil type cosmetic after 24 hours is 20,000 mPa·s or less as a measurement value (25°C, 6 rpm, 1 minute) by a B-type viscometer, it is preferable that the water-in-oil type cosmetic after 24 hours is stored at room temperature for 1 month, and the viscosity V1 of the water-in-oil type cosmetic after 1 month maintains 85% or more of the viscosity V0 of the water-in-oil type cosmetic after 24 hours.

[0020] According to the water-in-oil type cosmetic of this composition, under normal use conditions, since the viscosity is a certain level or more over a long period, the quality as a cosmetic is maintained, and it is possible to provide a water-in-oil type cosmetic with higher stability while maintaining an excellent usability.

[0021] In the water-in-oil type cosmetic of the present invention, the viscosity V0 of the prepared water-in-oil type cosmetic after 24 hours is 20,000 mPa·s or less as a measurement value (25°C, 6 rpm, 1 minute) by a B-type viscometer, When the freeze-thaw process, which involves storing the water-in-oil type cosmetic after 24 hours at -20°C for one week and then allowing it to return to room temperature by leaving it standing in a room at normal temperature, is defined as one cycle, it is preferable that the viscosity V2 of the water-in-oil type cosmetic after repeating the freeze-thaw process 10 times maintains 70% or more of the viscosity V0 of the water-in-oil type cosmetic after 24 hours.

[0022] According to the water-in-oil type cosmetic of this configuration, even under severe conditions (severe conditions) where freeze-thaw is repeated, the quality as a cosmetic is maintained because the viscosity is constant or more over a long period of time, and it is possible to provide a water-in-oil type cosmetic with significantly high stability while maintaining an excellent feeling of use.

Brief Description of the Drawings

[0023] [Figure 1] Figure 1 is a photograph showing an example of a sample of the base cosmetic for which a stability evaluation test was conducted.

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the water-in-oil type cosmetic according to the present invention will be described. However, the present invention is not limited to the following description, and various modifications are possible as long as they do not deviate from the technical idea of the present invention.

[0025] <Overall Configuration> The water-in-oil type cosmetic according to the present invention is a high water content type W / O type cosmetic containing 50% by mass or more of water. The upper limit value of the water content is not particularly defined as long as it is a water-in-oil type cosmetic, but for example, it can be 80% by mass or less. The water-in-oil type cosmetic according to the present invention contains, as main components, (A) dipolyhydroxy fatty acid polyalkylene glycol, (B) sesqui fatty acid sorbitan, and (C) an oil thickener.

[0026] [(A) Dipolyhydroxy Fatty Acid Polyalkylene Glycol] (A) The dipolyhydroxy fatty acid polyalkylene glycol is an essential component in the water-in-oil cosmetic composition according to the present invention and acts as a surfactant (emulsifier). The fatty acid in the dipolyhydroxy fatty acid polyalkylene glycol is preferably a fatty acid with 13 to 22 carbon atoms, preferably a straight-chain fatty acid with 16 to 20 carbon atoms, and more preferably stearic acid with 18 carbon atoms. The alkylene group in the dipolyhydroxy fatty acid polyalkylene glycol is preferably an ethylene group or a propylene group, and more preferably an ethylene group. Therefore, polyethylene glycol dipolyhydroxystearate is preferred as the dipolyhydroxy fatty acid polyalkylene glycol. Polyethylene glycol dipolyhydroxystearate with an average number of added ethylene oxides of about 10 to 50 can be used, but for example, PEG-30 dipolyhydroxystearate (polyethylene glycol dipolyhydroxystearate with an average number of added ethylene oxides of 30) is available on the market and can be preferably used. By using polyethylene glycol dipolyhydroxystearate as a surfactant (emulsifier), it works in cooperation with sorbitan sesquicate, component (B), to disperse the aqueous component as fine emulsion particles within the oily component, thereby improving both the feel and stability of the cosmetic. The average particle size of the emulsion particles in the water-in-oil cosmetic according to the present invention is several μm to 10 μm (for example, about 5 μm). This average particle size is smaller than the average particle size of emulsion particles in conventional water-in-oil cosmetics and has sufficient stability. The average particle size of the emulsion particles can be determined by dynamic light scattering after preparing the water-in-oil cosmetic (emulsion) and storing it at room temperature for one day. The content of dipolyhydroxy fatty acid polyalkylene glycol in the water-in-oil cosmetic is not specifically defined as long as it is a valid water-in-oil cosmetic, but for example, it can be 0.5 to 10% by mass.

[0027] [(B) Sorbitan sesquicarbonate] Component (B), sorbitan sesquifatty acid, is an essential component in the water-in-oil cosmetic composition according to the present invention and acts as a surfactant. Sorbitan sesquifatty acid is a nonionic surfactant. The fatty acid in sorbitan sesquifatty acid is preferably a fatty acid with 13 to 22 carbon atoms, preferably a branched-chain fatty acid with 16 to 20 carbon atoms, and more preferably isostearic acid with 18 carbon atoms. Therefore, sorbitan sesquiisostearate is preferred as the sorbitan sesquifatty acid. By using sorbitan sesquiisostearate as a surfactant, it works in cooperation with component (A), dipolyhydroxy fatty acid polyalkylene glycol, to disperse the aqueous component as fine emulsion particles within the oily component, thereby improving both the feel and stability of the cosmetic composition. Sorbitan sesquiisostearate is an ester of sorbitan and isostearic acid, and its name (sesqui) suggests that the molar ratio of sorbitan (let's call it B1) to isostearic acid (let's call it B2) is B1:B2=1:1.5. However, sorbitan sesquiisostearate cannot actually have a molar ratio of B1:B2=1:1.5 in its molecular structure. In reality, it is a mixture of esters with different molar ratios of B1:B2=1:1, B1:B2=1:2, and B1:B2=1:3 or higher, and furthermore, it is a mixture that also contains unreacted B1 and B2 in addition to the esters. Therefore, B1:B2=1:1.5 is considered to be the average of the molar ratios. There is no specific limit on the content of sorbitan sesquifatty acid in water-in-oil cosmetics as long as it is a valid water-in-oil cosmetic, but for example, it can be 0.1 to 10% by mass.

[0028] [(C) Oil thickener] (C) The oil thickener, which is component (C), is an essential component in the water-in-oil cosmetic composition according to the present invention and is one of the components (oily components) that form the oil phase. Examples of oil thickeners include polysaccharide fatty acid esters, (hydrogenated castor oil / sebacic acid) copolymers, (castor oil / isophorone diisocyanate (IPDI)) copolymers, and organically modified clay minerals. Disteardimonium hectorite is an example of an organically modified clay mineral. Among these oil thickeners, polysaccharide fatty acid esters are preferred. As polysaccharide fatty acid esters, sucrose fatty acid esters, dextrin fatty acid esters, and inulin fatty acid esters, in which the sugar chain portion is a disaccharide, are preferred. As a dextrin fatty acid ester, palmitate dextrin is preferred. By using palmitate dextrin as an oil thickener, it is possible to improve the moist feeling while suppressing stickiness when the cosmetic is applied to the skin, thereby improving the feel of the cosmetic, such as "freshness," "lightness of spreadability," and "skin compatibility." There are no specific regulations regarding the content of oil thickeners in water-in-oil type cosmetics, as long as the composition is valid as a water-in-oil type cosmetic; however, for example, it can be 0.1 to 10% by mass.

[0029] [(D) Powder] The water-in-oil cosmetic composition according to the present invention may further contain (D) powder. Examples of the powder include (D1) fine metal oxide particles and (D2) pigments.

[0030] [(D1) Fine particle metal oxide] The (D1) component, fine particle metal oxide, is added for UV protection and is used in UV protection agents, makeup bases, foundations, etc. The fine particle metal oxide is contained in the oil phase of water-in-oil type cosmetics. The fine particle metal oxide is not particularly limited as long as it is an inorganic fine particle that can block ultraviolet rays and can be used in cosmetics. Specific examples include fine particle titanium dioxide, fine particle iron-containing titanium dioxide, fine particle zinc oxide, fine particle cerium oxide, and composites thereof. Among these, from the viewpoint of UV shielding effect, one or two selected from fine particle titanium dioxide and fine particle zinc oxide are preferably used. The shape of the inorganic fine particles can be spherical, polyhedral, spindle-shaped, needle-shaped, and plate-shaped, and is not particularly limited as long as it can be used in cosmetics for UV shielding purposes. From the viewpoint of UV shielding effect and usability, the volume average particle diameter of the fine particle metal oxide is preferably 10 to 200 nm, more preferably 20 to 100 nm, and most preferably 20 to 50 nm. The volume-average particle size of fine metal oxide particles can be measured using a laser diffraction / scattering particle size distribution analyzer. These fine metal oxide particles are preferably surface-treated with dimethicone. Such surface treatment contributes to lowering the viscosity of the water-in-oil cosmetic while improving the lipophilicity and dispersibility of the fine metal oxide particles, allowing them to exist stably in the oil phase. There is no specific limit to the content of fine metal oxide particles in a water-in-oil cosmetic, as long as it functions as a water-in-oil cosmetic; however, it can be, for example, 3 to 30% by mass.

[0031] [(D2) Pigment] The pigment, which is component (D2), is added for coloring and shape retention and is used in base cosmetics, foundations, etc. The pigment is included in the oil phase in water-in-oil cosmetics. Examples of pigments include mica, titanium mica, sericite, talc, rutile-type titanium dioxide, yellow iron oxide, red iron oxide, and black iron oxide. These pigments are preferably surface-treated with dimethicone, similar to fine-particle metal oxides. There is no particular limit on the pigment content in water-in-oil cosmetics as long as they function as water-in-oil cosmetics, but when added, it can be, for example, 3 to 30% by mass.

[0032] [(E) Organic UV absorbers] The water-in-oil cosmetic composition according to the present invention may further contain (E) an organic ultraviolet absorber. The organic ultraviolet absorber, which is component (E), is contained in the oil phase of the water-in-oil cosmetic composition. By incorporating the organic ultraviolet absorber, a cosmetic composition having ultraviolet protection ability can be provided. The organic ultraviolet absorber is not particularly limited as long as it can be incorporated into the cosmetic composition. For example, cinnamic acid derivatives such as ethylhexyl methoxycinnamate, ethylhexyl paramethoxycinnamate, isopropyl methoxycinnamate, and isoamyl methoxycinnamate; PABA derivatives such as para-aminobenzoic acid (hereinafter abbreviated as "PABA"), ethyl PABA, ethyl-dihydroxypropyl PABA, ethylhexyl-dimethyl PABA, and glyceryl PABA; salicylic acid derivatives such as homosalate, ethylhexyl salicylate, dipropylene glycol salicylate, and TEA salicylate; benzophenone derivatives such as benzophenone-1, benzophenone-2, benzophenone-3 or oxybenzone, benzophenone-4, benzophenone-5, benzophenone-6, benzophenone-8, benzophenone-9, and benzophenone-12; 3-benzylidene camphor, 4-methylbenzylidene camphor, benzylidene camphor sulfonic acid, benzalkonium camphor methosulfate, and terephthalylidene Benzylidene camphor derivatives such as disodium camphor sulfonic acid and polyacrylamide methylbenzylidene camphor; triazine derivatives such as ethylhexyl triazone, anisotriazine, diethylhexylbutamide triazone, 2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine, ethylhexyl triazone, and 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine; phenylbenzimidazole derivatives such as phenylbenzimidazole sulfonic acid and phenyldibenzimidazole disodium tetrasulfonate; phenylbenzotriazole derivatives such as drometrizole trisiloxane and methylenebis(benzotriazolyltetramethylbutylphenol); anthranil derivatives such as menthyl anthranilate; imidazoline derivatives such as dimethoxybenzylidene oxoimidazolidine propionate 2-ethylhexyl;Examples include benzalmalonate derivatives such as polyorganosiloxanes having a benzalmalonate functional group; 4,4-diarylbutadiene derivatives such as 1,1-dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene; octocrylene, 2-[4-(diethylamino)-2-hydroxybenzoyl]hexyl benzoate, diethylaminohydroxybenzoylhexyl benzoate, 4-tert-butyl-4'-methoxydibenzoylmethane, and bis-ethylhexyloxyphenol methoxyphenyl triazine. These organic UV absorbers may be used alone or in combination of two or more. From the viewpoint of UV absorption capacity and skin safety, ethylhexyl paramethoxycinnamate is preferably used as the organic UV absorber. Furthermore, it is also preferable to use bis-ethylhexyloxyphenol methoxyphenyl triazine and ethylhexyl paramethoxycinnamate in combination to provide UVA protection.

[0033] [(F) Water-soluble inorganic salts] The water-in-oil cosmetic composition according to the present invention may further contain (F) a water-soluble inorganic salt. The water-soluble inorganic salt, which is component (F), is added for stabilization and is contained in the aqueous phase of the water-in-oil cosmetic composition. Examples of water-soluble inorganic salts include sodium chloride, potassium chloride, calcium chloride, magnesium chloride, and magnesium sulfate, with sodium chloride being preferred.

[0034] [(G) Other ingredients] The water-in-oil cosmetic composition according to the present invention may contain, as (G) other components, components that form a liquid component (oil phase or aqueous phase) in addition to the above components. Examples of components that form the oil phase (oily components) include isononyl isononanoate (solubilizer), isopropyl lauroyl sarcosinate (emollient), and dimethicone (silicone oil). Examples of components that form the aqueous phase (aqueous components) include butylene glycol and phenoxyethanol.

[0035] <Stability of cosmetics> As explained in "Problems the Invention Aims to Solve," water-in-oil cosmetics require both excellent usability and high stability. The inventors diligently studied criteria for evaluating the usability and stability of water-in-oil cosmetics and found that (1) the viscosity of the cosmetic the next day (viscosity 24 hours after preparation), (2) the change in viscosity over a long period under normal usage conditions, and (3) the change in viscosity over a long period under severe conditions are effective in evaluating the usability and stability of the cosmetic. Based on these findings, the following conditions (1) to (3) were established.

[0036] (1) The viscosity V0 of the prepared water-in-oil cosmetic composition after 24 hours shall be 20,000 mPa·s or less, as measured by a B-type viscometer (25°C, 6 rpm, 1 min). (2) Store the water-in-oil cosmetic after 24 hours at room temperature for one month, and ensure that the viscosity V1 of the water-in-oil cosmetic after one month is at least 85% of the viscosity V0 of the water-in-oil cosmetic after 24 hours. (3) When the water-in-oil cosmetic composition is stored at -20°C for one week after 24 hours, and then returned to room temperature by being left to stand in a room at room temperature, one cycle of this freeze-thaw process is performed, and the viscosity V2 of the water-in-oil cosmetic composition after 10 cycles of this freeze-thaw process is maintained at 70% or more of the viscosity V0 of the water-in-oil cosmetic composition after 24 hours.

[0037] Condition (1) is set so that the viscosity V0 of the water-in-oil cosmetic does not become excessive, and is related to the feel of the cosmetic. Conditions (2) and (3) are set so that the viscosity V0 of the water-in-oil cosmetic is maintained during the period of use, and are related to the stability (maintenance of quality) of the cosmetic. If conditions (1) and (2) are met, it is evaluated that high stability is ensured while suppressing a decrease in the feel of the cosmetic under normal usage conditions. If conditions (1) and (3) are met, it is evaluated that high stability is ensured while suppressing a decrease in the feel of the cosmetic even under harsh conditions of repeated freeze-thaw cycles (severe conditions). Although these evaluations are basically performed separately, if conditions (1) and (3), which are severe conditions, are met, it can be assumed that conditions (1) and (2) are also met.

[0038] The water-in-oil cosmetic composition according to the present invention, by containing at least the above components (A) to (C), satisfies at least conditions (1) and (2), and may even satisfy conditions (1) and (3), thereby significantly improving stability while suppressing a decrease in the feel of the cosmetic composition. The results of the stability evaluation of a base cosmetic composition, which is an example of a water-in-oil cosmetic composition, will be explained in detail in the examples described below. [Examples]

[0039] As a specific example of the water-in-oil cosmetic composition according to the present invention, a base cosmetic and a liquid foundation were prepared by combining components (A) to (C) above, along with components (D) to (G) as appropriate. These examples will be described below.

[0040] [Example 1] <Preparation of base makeup> (A) Component: 1 part by mass of polyethylene glycol dipolyhydroxystearate (PEG-30 dipolyhydroxystearate), (B) Component: 0.5 parts by mass of sorbitan sesquiisostearate, (C) Component: 0.5 parts by mass of dextrin palmitate, (D) Component: 3 parts by mass of dimethicone-treated talc (SA-Talc JA-46R (manufactured by Miyoshi Chemical Co., Ltd.), the same applies hereafter), 2 parts by mass of dimethicone-treated rutile-type titanium dioxide (average particle size 250 nm), and dimethicone-treated 0.03 parts by mass of iron oxide (SA-Red R-516PS (100%) (manufactured by Miyoshi Chemical Co., Ltd., the same applies hereafter)), along with 7 parts by mass of isononyl isononanoate, 1 part by mass of isopropyl lauroyl sarcosinate, 7.5 parts by mass of ethylhexyl methoxycinnamate, 1.5 parts by mass of diethylamino hydroxybenzoyl hexyl benzoate, and 7.27 parts by mass of dimethicone (KF-96A-6cs (manufactured by Shin-Etsu Chemical Co., Ltd., the same applies hereafter)) were added to form an oily component. To this oily component, 0.3 parts by mass of sodium chloride, 13.5 parts by mass of butylene glycol, and an appropriate amount of phenoxyethanol were added as aqueous components, and water was added to make a total of 100 parts by mass. This was then emulsified (dispersed) in a homogenizer to obtain the base cosmetic of Example 1, which is a water-in-oil type cosmetic.

[0041] <Viscosity measurement> The base cosmetic composition of Example 1 was dispensed into a 70 mL mayonnaise bottle, and a Type B viscometer (model number: TVB-10M viscometer, manufactured by Toki Sangyo Co., Ltd.) was placed directly into it. The viscosity of the base cosmetic composition was measured under the specified measurement conditions (25°C, rotor No. 4, 6 rpm, 1 minute). The viscosity immediately after preparation (viscosity on the day) was 10200 mPa·s, and the viscosity after 24 hours (viscosity the next day) was 9600 mPa·s. Note that the viscosity on the day is not subject to the stability evaluation described later, but was measured for reference.

[0042] [Storage conditions] Immediately after preparation, the base cosmetic of Example 1 was placed into two 70 mL mayonnaise bottles, each with a lid, and left to stand for 24 hours. One mayonnaise bottle was stored at room temperature (25°C) for one month, i.e., under normal usage conditions. The other mayonnaise bottle was cooled to -20°C to freeze the base cosmetic and stored in that state for one week. Then, it was left to stand in a room at room temperature to return to room temperature and thaw the base cosmetic. This freeze-thaw process was repeated 10 times, i.e., under harsh conditions of repeated freeze-thawing.

[0043] [Viscosity change] When the viscosity of the primer cosmetic of Example 1, stored under normal usage conditions, was measured using a B-type viscometer under the same conditions as described above, the viscosity after one month was 8600 mPa·s. In other words, the viscosity retention rate after one month, based on the viscosity the next day, was 89.6%. This result suggests that the primer cosmetic of Example 1 maintained its quality, with no significant change in viscosity from the initial viscosity (after 24 hours) even after one month.

[0044] <Stability Evaluation> The stability of the primer cosmetic samples stored under normal use conditions and under severe conditions was evaluated based on their appearance. The evaluation criteria were as follows: A: Both samples showed no change whatsoever from their initial state. B: Only the samples subjected to severe conditions showed slight leakage of liquid components on the surface, but this does not pose a practical problem. C: In at least one sample, the separated liquid component is observed on or near the sample surface with a thickness of 1 mm or more. D: In at least one sample, the separated liquid component is found to constitute more than one-third of the total sample. As an example, Figure 1 shows photographs of primer cosmetic samples that were evaluated as having stability ratings A, C, and D. Note that the sample evaluated as B is not shown here because it is difficult to distinguish it from the sample evaluated as A in the photograph. The primer cosmetic of Example 1 was evaluated as A, confirming its excellent stability.

[0045] <Evaluation of user experience> The user experience of the primer in Example 1 was evaluated based on "moisture," "ease of spread," and "skin compatibility." The evaluation test was conducted by three panelists (sensory evaluation specialists), who independently evaluated the skin condition and then exchanged opinions with each other before making their final decisions. The evaluation criteria were as follows: A: Excellent B: Good C: Normal D: Bad The makeup base used in Example 1 was rated A for "moisture," "ease of application," and "skin compatibility," confirming that it provides an excellent user experience.

[0046] [Comparative Examples 1-5] The water-in-oil cosmetic composition according to the present invention (primer cosmetic composition of Example 1) contains PEG-30 dipolyhydroxystearate as component (A) and sorbitan sesquiisostearate as component (B) as surfactants. For comparison, a primer cosmetic composition containing component (A) but not component (B) (Comparative Example 1), a primer cosmetic composition containing component (B) but not component (A) (Comparative Example 2), and primer cosmetic compositions containing other surfactants but not containing either component (A) or component (B) (Comparative Examples 3-5) were prepared.

[0047] For the base cosmetic compositions of Comparative Examples 1 to 5 that were measurable, the viscosity on the day of use, the viscosity the next day, and the viscosity after one month were measured using the same method as in Example 1. Furthermore, for the base cosmetic compositions of Comparative Examples 1 to 5 that were evaluable, the stability as a cosmetic composition and the feel of use were evaluated using the same criteria as in Example 1.

[0048] Table 1 shows the formulations and evaluations of the base makeup formulations for Comparative Examples 1-5. Table 1 also includes the formulation and evaluation of the base makeup formulation for Example 1, for easier comparison with the water-in-oil cosmetic formulation according to the present invention. In Table 1, blank spaces indicate that an ingredient was not included. Regarding the evaluations in Table 1, the viscosity on the day of preparation was not measured for Comparative Examples 1-5, as it is not included in the stability evaluation (these spaces are left blank). Where the viscosity column shows "-", it means that the emulsification state was poor from the beginning of preparation, and viscosity measurement was not possible. Regarding usability, formulations with poor emulsification are unsuitable for use as base makeup formulations, so no evaluation was performed, and the usability column is marked with "-".

[0049] [Table 1]

[0050] A primer containing ingredient (A) but not ingredient (B) (Comparative Example 1) received a certain level of evaluation (rating B or higher) for its feel, but under severe conditions, its emulsification state deteriorated significantly, and it was evaluated as having poor stability. A primer containing ingredient (B) but not ingredient (A) (Comparative Example 2) had a poor emulsification state from the beginning of preparation and was unsuitable for use as a primer. Primers containing other surfactants but not containing either ingredient (A) or ingredient (B) (Comparative Examples 3-5) also had a poor emulsification state from the beginning of preparation and were unsuitable for use as a primer.

[0051] [Examples 2-5, Comparative Example 6] The water-in-oil cosmetic composition according to the present invention (primer cosmetic composition of Example 1) contains dextrin palmitate (oil thickener) as component (C). However, primer cosmetic compositions with a modified content of dextrin palmitate (Example 2) and primer cosmetic compositions containing oil thickeners other than dextrin palmitate (Examples 3-5) were prepared. For comparison, a primer cosmetic composition without component (C) (Comparative Example 6) was also prepared.

[0052] According to Example 1, base cosmetics of Examples 2 to 5 and Comparative Example 6 were prepared. For those that could be measured and evaluated for viscosity, viscosity measurement and evaluation were performed in the same manner as in Example 1.

[0053] The formulations and evaluations of the base cosmetics of Examples 2 to 5 and Comparative Example 6 are shown in Table 2. For easier comparison with the water-in-oil cosmetics according to the present invention, the formulation and evaluation of the base cosmetic of Example 1 are also shown in Table 2. Regarding the formulations in Table 2, a blank means that it was not formulated. The notation "surfactant" in Table 2 is an abbreviation for "surfactant".

[0054]

Table 2

[0055] For the base cosmetic of Example 1, the base cosmetic (Example 2) in which the content of dextrin palmitate as component (C) was changed to 2 times (1 part by mass) had excellent stability, and for the usability, all of "freshness", "lightness of stretch", and "skin compatibility" were evaluated as A, and it was confirmed that excellent usability was obtained. For the base cosmetics (Examples 3 to 5) containing oil thickeners other than dextrin palmitate, both stability and usability were evaluated to a certain extent (evaluation of B or higher). On the other hand, the base cosmetic (Comparative Example 6) not containing component (C) obtained a certain evaluation (evaluation of B or higher) for usability, but had a poor emulsified state under severe conditions and was evaluated as having poor stability.

[0056] [Examples 6, Comparative Examples 7 to 8] The water-in-oil cosmetic according to the present invention (the base cosmetic of Example 1) contains 50% by mass or more of water, but base cosmetics (Examples 6, Comparative Examples 7 to 8) with the water content changed were prepared. The base cosmetic of Example 6 had an increased water content compared to the base cosmetic of Example 1, and the base cosmetics of Comparative Examples 7 to 8 had a water content of less than 50% by mass.

[0057] According to Example 1, base cosmetics of Example 6 and Comparative Examples 7 to 8 were prepared, and for those for which viscosity measurement and evaluation were possible, viscosity measurement and evaluation were performed in the same manner as in Example 1.

[0058] The formulations and evaluations of the base cosmetics of Example 6 and Comparative Examples 7 to 8 are shown in Table 3. For easier comparison with the water-in-oil type cosmetics according to the present invention, the formulation and evaluation of the base cosmetics of Example 1 are also shown in Table 3. In addition, the meaning of "-" in the evaluation column of Table 3 is the same as that described in Table 1. The notation "surfactant" in Table 3 is an abbreviation for "surfactant".

[0059]

Table 3

[0060] For the base cosmetic of Example 6 in which the water content was increased with respect to the base cosmetic of Example 1, a certain evaluation (B evaluation or higher) was obtained for stability, and for the usability, all of "freshness", "lightness of stretch", and "skin compatibility" were evaluated as A, and it was confirmed that excellent usability was obtained. On the other hand, the base cosmetics of Comparative Examples 7 to 8 in which the water content was less than 50% by mass could not be said to have good stability, and only some evaluations regarding usability were good. And when comparing the base cosmetic of Comparative Example 7 and the base cosmetic of Comparative Example 8, the base cosmetic of Comparative Example 7 with a lower water content tended to be inferior in stability.

[0061] [Example 7] <Preparation of Liquid Foundation> In the above Examples 1 to 6, those in which the water-in-oil type cosmetics according to the present invention were prepared as base cosmetics were exemplified, but Example 7 is a liquid foundation prepared. The liquid foundation of Example 7 can also be obtained by mixing the oily component and the aqueous component together and emulsifying (dispersing) this with a homogenizer, in the same manner as the base cosmetics of Examples 1 to 6. The formulation of the liquid foundation of Example 7 is shown in Table 4. In addition, the notation "surfactant" in Table 4 is an abbreviation for "surfactant".

[0062] Here, among the components shown in Table 4, dimethicone-treated titanium dioxide was SA-Titanium CR-50 (100%) (manufactured by Miyoshi Chemical Co., Ltd.), dimethicone-treated yellow iron oxide was SA-Yellow LL-100P (100%) (manufactured by Miyoshi Chemical Co., Ltd.), and dimethicone-treated black iron oxide was SA-Black BL-100P (100%) (manufactured by Miyoshi Chemical Co., Ltd.).

[0063] [Table 4]

[0064] <Viscosity> The viscosity of the liquid foundation of Example 7 was measured using a method similar to that of Example 1. As a result, the viscosity V0 of the prepared liquid foundation after 24 hours was 20,000 mPa·s or less, as measured by a B-type viscometer (25°C, 6 rpm, 1 min). When the liquid foundation was stored at room temperature for one month after 24 hours, the viscosity V1 of the liquid foundation after one month maintained 85% or more of the viscosity V0 of the liquid foundation after 24 hours. When the liquid foundation was stored at -20°C for one week after 24 hours, and then returned to room temperature by being left to stand in a room at room temperature, this freeze-thaw process was considered one cycle. After repeating this freeze-thaw process 10 times, the viscosity V2 of the liquid foundation maintained 70% or more of the viscosity V0 of the liquid foundation after 24 hours. Thus, the liquid foundation of Example 7 showed no significant change from its initial viscosity (after 24 hours) even after one month, suggesting that its quality was maintained.

[0065] <Stability and usability> The stability and feel of the liquid foundation in Example 7 were evaluated using the same criteria as the primer cosmetic described earlier. As a result, the stability was rated as A, and the feel was also rated as A in all aspects: "moisture," "ease of application," and "skin compatibility." Thus, it was confirmed that the water-in-oil cosmetic composition according to the present invention possesses both high stability and excellent feel, even in liquid foundation form. [Industrial applicability]

[0066] The water-in-oil cosmetic composition according to the present invention can be used as a cosmetic composition such as a UV protection agent, a makeup base, a foundation, a basic lotion, or a serum.

Claims

1. A water-in-oil cosmetic composition containing 50% by mass or more of water, The following components (A) to (C): (A) Dipolyhydroxy fatty acid polyalkylene glycol (B) Sorbitan sesquicarbonate (C) Oil thickener A water-in-oil cosmetic containing [a specific ingredient].

2. The water-in-oil cosmetic composition according to claim 1, wherein component (A) is polyethylene glycol dipolyhydroxystearate.

3. The water-in-oil cosmetic composition according to claim 1, wherein component (B) is sorbitan sesquiisostearate.

4. The water-in-oil cosmetic composition according to claim 1, wherein component (C) is dextrin palmitate.

5. (D) The water-in-oil cosmetic composition according to claim 1, further comprising a powder.

6. The viscosity V0 of the prepared water-in-oil cosmetic composition after 24 hours was 20,000 mPa·s or less, as measured by a B-type viscometer (25°C, 6 rpm, 1 min). The water-in-oil cosmetic according to any one of claims 1 to 5, wherein the water-in-oil cosmetic after 24 hours is stored at room temperature for one month, and the viscosity V1 of the water-in-oil cosmetic after one month is maintained at 85% or more of the viscosity V0 of the water-in-oil cosmetic after 24 hours.

7. The viscosity V0 of the prepared water-in-oil cosmetic composition after 24 hours was 20,000 mPa·s or less, as measured by a B-type viscometer (25°C, 6 rpm, 1 min). The water-in-oil cosmetic according to any one of claims 1 to 5, wherein when the water-in-oil cosmetic after 24 hours is stored at -20°C for one week and then returned to room temperature by being left to stand in a room at room temperature, the viscosity V2 of the water-in-oil cosmetic after 10 cycles of the freeze-thaw process maintains 70% or more of the viscosity V0 of the water-in-oil cosmetic after 24 hours.

Images