Sunscreen cosmetic

Abstract

[Problem] The purpose of the present invention is to provide a sunscreen cosmetic in which the UV ray protective ability of a UV ray absorbing agent has been improved. [Solution] This sunscreen cosmetic is characterized by including (A) a UV ray absorbing agent, (B) a dicarboxylic acid ester, and (C) water, wherein the mixing ratio ((B) / (C)) of the (B) dicarboxylic acid ester to the (C) water is 1.8% or greater by mass ratio.

Description

Sunburn-preventing cosmetics

[0001] The present invention relates to a sunburn-preventing cosmetic with improved ultraviolet ray protection ability.

[0002] Cosmetics having a sunburn-preventing effect suppress adverse effects on the skin by reducing the amount of ultraviolet rays reaching the skin coated with the cosmetics due to the action of ultraviolet ray absorbers or ultraviolet ray scattering agents formulated in the cosmetics.

[0003] As an index of the ultraviolet ray protection effect of cosmetics, the Sun Protection Factor (SPF) is most widely known, and the ultraviolet ray protection effect is expressed as an SPF value (for example, "SPF30", etc.). In Japan, for ultraviolet rays in the UVA region, PFA (Protection Factor of UVA) or UVA-PF (UVA Protection factor of product) is used, and the degree of the UVA protection effect of the product is indicated by PA (Protection grade of UVA) classification based on the value of PFA or UVA-PF (for example, "PA++", etc.). In the United States, the Critical Wavelength (CW), which shows the balance of the protection effects of UVA and UVB, is used.

[0004] In recent years, in order to suppress adverse effects on the skin caused by ultraviolet rays, there has been a demand for cosmetics that exhibit a high ultraviolet ray protection effect in a wide wavelength range from UVA to UVB. For example, sunburn-preventing products claiming SPF 50 or higher (50+) and PA++++ have come to be marketed.

[0005] The ultraviolet ray protection effect in sunburn-preventing cosmetics is exerted by the ultraviolet ray protectants formulated therein, that is, ultraviolet ray absorbers and ultraviolet ray scattering agents. However, when moisture comes into contact with the applied cosmetics, the ultraviolet ray protectants may flow out from the skin surface, or when heat is applied to the coating film in a high-temperature environment, the ultraviolet ray absorbers and the like may deteriorate, resulting in a decrease in the ultraviolet ray protection effect. In addition, some ultraviolet ray absorbers have a reduced ultraviolet ray absorption ability (photo-deterioration) due to light irradiation.

[0006] To suppress the decrease in UV protection when using sunscreen cosmetics as described above, technologies have been developed to suppress the photodegradation of UV absorbers (Patent Documents 1 and 2), and cosmetics have been developed that have innovative properties such as not decreasing in UV protection effect even when exposed to moisture or heat, and on the contrary improving in protection effect (Patent Documents 3 and 4).

[0007] While various technologies have been proposed to suppress the decline in the UV protection effect of sunscreen cosmetics, the increase in UV radiation due to changes in the natural environment is expected to become even more concerning in the future, and there is a demand for sunscreen cosmetics with high UV protection.

[0008] Japanese Patent No. 5540243, International Publication No. 2017 / 057676, International Publication No. 2016 / 068300, International Publication No. 2020 / 032241

[0009] The present invention aims to provide a sunscreen cosmetic that can achieve a high level of UV protection by improving the UV protection capacity of the UV absorber.

[0010] The inventors conducted extensive research to solve the aforementioned problems and, as a result, discovered that incorporating a dicarboxylic acid ester improves the UV protection capacity of the UV absorber, thus completing the present invention.

[0011] In other words, the present invention provides a sunscreen cosmetic comprising (A) an ultraviolet absorber, (B) a dicarboxylic acid ester, and (C) water, wherein the mass ratio of (B) dicarboxylic acid ester to (C) water is 0.5% or more. Preferably, the mass ratio of (B) dicarboxylic acid ester to (C) water is 1.8% or more.

[0012] By adopting the above configuration, the present invention makes it possible to create a sunscreen cosmetic in which the UV protection capacity of the UV absorber incorporated into the sunscreen cosmetic is improved.

[0013] The sunscreen cosmetic composition of the present invention is characterized by comprising (A) an ultraviolet absorber, (B) a dicarboxylic acid ester, and (C) water. The components constituting the cosmetic composition of the present invention will be described in detail below.

[0014] <(A) UV absorber> The (A) UV absorber (hereinafter sometimes simply referred to as "(A) component") incorporated into the sunscreen cosmetic of the present invention is a substance that is usually incorporated into cosmetics for the purpose of preventing ultraviolet rays from affecting skin cells by absorbing energy through a chemical mechanism and converting it into energy such as heat.

[0015] (A) Examples of UV absorbers include benzoic acid derivatives, salicylic acid derivatives, cinnamic acid derivatives, dibenzoylmethane derivatives, β,β-diphenyl acrylate derivatives, benzophenone derivatives, benzylidene camphor derivatives, phenylbenzimidazole derivatives, triazine derivatives, phenylbenzotriazole derivatives, anthranyl derivatives, imidazoline derivatives, benzalmalonate derivatives, 4,4-diarylbutadiene derivatives, etc. Specific examples and trade names are listed below, but are not limited to these.

[0016] Examples of benzoic acid derivatives include ethyl para-aminobenzoate (PABA), ethyl dihydroxypropyl PABA, dimethyl PABA ethylhexyl (e.g., "Escalol® 507"; ISP Japan), glyceryl PABA, PEG-25 PABA (e.g., "Ubinal® P25"; BASF Japan), and diethylaminohydroxybenzoyl hexyl benzoate (e.g., "Ubinal® A Plus"; BASF Japan).

[0017] Examples of salicylic acid derivatives include homosalate ("Eusorex® HMS"; Merck Performance Materials), ethylhexyl salicylate (e.g., "NeoHeliopan® OS"; Symrise), dipropylene glycol salicylate (e.g., "Dipsal"; Skell), and TEA salicylate (e.g., "NeoHeliopan® TS"; Symrise).

[0018] Examples of cinnamic acid derivatives include ethylhexyl methoxycinnamate (e.g., "Parsol® MCX"; DSM), cresyl methoxycinnamate, isopropyl methoxycinnamate, isoamyl paramethoxycinnamate (e.g., "Neohliopan® E1000"; Symrise), cinoxate, DEA methoxycinnamate, methyl diisopropylcinnamate, glyceryl-ethylhexanoate-dimethoxycinnamate, and di-(2-ethylhexyl)-4'-methoxybenzalmalonate.

[0019] Examples of dibenzoylmethane derivatives include 4-tert-butyl-4'-methoxydibenzoylmethane (e.g., "Parsol® 1789"; DSM Corporation).

[0020] Examples of β,β-diphenyl acrylate derivatives include octocrylene (e.g., "Ubinal® N539"; BASF Japan).

[0021] Examples of benzophenone derivatives include benzophenone-1 (e.g., "Uvinal® 400"; BASF Japan), benzophenone-2 (e.g., "Uvinal® D50"; BASF Japan), benzophenone-3 or oxybenzone (e.g., "Uvinal® M40"; BASF Japan), benzophenone-4 (e.g., "Uvinal® MS40"; BASF Japan), benzophenone-5, benzophenone-6 (e.g., "Helisorb 11"; Norquay), benzophenone-8 (e.g., "Spectra-Sorb UV-24"; American Cyanamide Corporation), benzophenone-9 (e.g., "Uvinal® DS-49"; BASF Japan), and benzophenone-12.

[0022] Examples of benzylidene camphor derivatives include 3-benzylidene camphor (e.g., "Mexoryl SD"; CIMEX), 4-methylbenzylidene camphor, benzylidene camphor sulfonic acid (e.g., "Mexoryl SL"; CIMEX), benzalkonium camphor methosulfate (e.g., "Mexoryl SO"; CIMEX), terephthalylidene disodium camphor sulfonic acid (e.g., "Mexoryl SX"; CIMEX), and polyacrylamide methylbenzylidene camphor (e.g., "Mexoryl SW"; CIMEX).

[0023] Examples of phenylbenzimidazole derivatives include phenylbenzimidazole sulfonic acid (e.g., "Eusorex® 232"; Merck Performance Materials) and phenyldibenzimidazole tetrasulfonate disodium (e.g., "Neoheliopan® AP"; Symrise).

[0024] Examples of triazine derivatives include bisethylhexyloxyphenol methoxyphenyl triazine (e.g., "Tinosorb® S"; BASF Japan), ethylhexyl triazone (e.g., "Ubinal® T150"; BASF Japan), diethylhexyl butamide triazone (e.g., "Ubasorb® HEB"; 3V Sigma), 2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine, and 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine.

[0025] Examples of phenylbenzotriazole derivatives include drometrizole trisiloxane (e.g., "Silatrizole"; Rhodia Simiy Co.) and methylenebis (benzotriazolyltetramethylbutylphenol) (e.g., "Tinosorb® M" (BASF Japan)).

[0026] Examples of anthranil derivatives include menthyl anthranilate (e.g., "NeoHeliopan® MA"; Symrise Inc.).

[0027] Examples of imidazoline derivatives include ethylhexyl dimethoxybenzylidene dioxoimidazolidine propionate.

[0028] Examples of benzalmalonate derivatives include polyorganosiloxanes having benzalmalonate functional groups (e.g., polysilicone-15; "Parsol® SLX"; DSM Corporation).

[0029] Examples of 4,4-diarylbutadiene derivatives include 1,1-dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene. As component (A) of the present invention, one or more selected from the group consisting of the above-mentioned ultraviolet absorbers may be used. In particular, it is preferable to use one or more selected from the group consisting of octocrylene, cresyl methoxycinnamate, ethylhexyl salicylate, homosalate, bis-ethylhexyloxyphenol methoxyphenyl triazine, ethylhexyl triazone, and diethylamino hydroxybenzoyl hexyl benzoate.

[0030] In the cosmetic composition according to the present invention, it is even more preferable that component (A) contains octocrylene, which is a β,β-diphenyl acrylate derivative. In this case, octocrylene may be used alone as component (A) of the present invention, or octocrylene may be used in combination with one or more of the other UV absorbers. Ethylhexyl methoxycinnamate is usually preferred in sunscreen cosmetics because it has excellent UV absorption ability and a good feel, but in the cosmetic composition according to the present invention, sufficient UV protection can be obtained without incorporating ethylhexyl methoxycinnamate. Therefore, the cosmetic composition of the present invention includes embodiments in which the amount of ethylhexyl methoxycinnamate is 5% by mass or less, less than 3% by mass or 1% by mass or less, and embodiments in which ethylhexyl methoxycinnamate is not incorporated.

[0031] (A) The amount of ingredient (A) is preferably 1 to 40% by mass, and more preferably 2 to 30% by mass, relative to the total amount of cosmetic product. If the amount of ingredient (A) is less than 1% by mass, it is difficult to obtain sufficient UV protection, and even if it is added at more than 40% by mass, an increase in UV protection commensurate with the amount added cannot be expected, and it is undesirable in that it may worsen stability and usability.

[0032] <(B) Dicarboxylic Acid Ester> The (B) dicarboxylic acid ester (hereinafter sometimes simply referred to as "component (B)") incorporated into the sunscreen cosmetic of the present invention is a condensation compound of a glycol, glycol ether, glycerin, and 2-ethylhexanol, etc., with a dicarboxylic acid, and refers to those commonly used in cosmetics. The dicarboxylic acid constituting the (B) dicarboxylic acid ester is not particularly limited as long as it is a dicarboxylic acid having 4 to 24 carbon atoms and containing a linear, branched, or cyclic structure. Examples of such dicarboxylic acids include succinic acid, adipic acid, sebacic acid, dodecanediic acid, undecanediic acid, tetradecanediic acid, hexadecanedioic acid, octadecanediic acid, 8-ethyloctadecanediic acid, eicosanedioic acid, docosanedioic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc.

[0033] (B) Examples of dicarboxylic acid esters, though not particularly limited, include (eicosanedioic acid / tetradecanedioic acid) polyglyceryl-10, cyclohexanedicarboxylic acid bisethoxydiglycol, 1,4-cyclohexanedicarboxylic acid bis(triethylene glycol monoethyl ether), adipate bis(diethylene glycol monoethyl ether), adipate bis(triethylene glycol monoethyl ether), diethoxyethyl succinate, and diethylhexyl succinate. One or more selected from this group may be used as component (B).

[0034] The (B) dicarboxylic acid ester of the present invention preferably includes a dicarboxylic acid ester comprising a dicarboxylic acid having 4 to 24 carbon atoms and polyglycerin. More specifically, one or more selected from the group consisting of (eicosanedioic acid / tetradecanedioic acid) polyglyceryl-10 and cyclohexanedicarboxylic acid bisethoxydiglycol are preferred.

[0035] A commercially available product may be used as the (B) dicarboxylic acid ester of the present invention. Examples of commercially available products include Neosolue®-Aqua and Neosolue®-AquaS ((eicosanedioic acid / tetradecanedioic acid) polyglyceryl-10), and Neosolue®-Aqualio (cyclohexane-1,4-dicarboxylic acid bisethoxydiglycol) (all manufactured by Nippon Seika Co., Ltd.).

[0036] Furthermore, the present invention exhibits a thermoboost effect, in which the UV protection effect is significantly improved compared to immediately after application of the cosmetic to the skin, due to the application of heat to the coated film after the cosmetic has been applied to the skin. This thermoboost effect is also described in Patent Document 4, but the present invention is superior in that the thermoboost effect is achieved at a lower temperature (30°C) than in conventional methods.

[0037] <(C) Water> The (C) water (hereinafter sometimes simply referred to as "(C) component") incorporated into the sunscreen cosmetic of the present invention is not particularly limited as long as it is a type commonly used in cosmetics, such as purified water, deionized water, and tap water.

[0038] The amount of (B) dicarboxylic acid ester and (C) water used in this invention is such that the ratio of (B) dicarboxylic acid ester to (C) water ((B) / (C)) is 0.5% or more by mass, preferably 1.0% or more, and more preferably 1.8% or more. If the mass ratio of (B) dicarboxylic acid ester to (C) water is less than 0.5%, the effect of improving the UV protection of (A) UV absorber is difficult to perceive.

[0039] When the cosmetic composition according to the present invention is an oil-in-water emulsion, a more preferred lower limit for the blending mass ratio of (B) dicarboxylic acid ester to (C) water ((B) / (C)) is 1.0% or more, 1.2% or more, 1.5% or more, 1.8% or more, or 2.0% or more, and a preferred upper limit is 10% or less, 9% or less, 8% or less, or 7% or less. Therefore, a preferred range is 1.0 to 10%, 1.2 to 9%, etc.

[0040] On the other hand, when the cosmetic composition according to the present invention is a water-in-oil emulsion, a more preferable lower limit for the blending mass ratio of (B) dicarboxylic acid ester to (C) water ((B) / (C)) is 5% or more, 8% or more, 10% or more, 12% or more, or 15% or more, and a preferred upper limit is 35% or less, 32% or less, 30% or less, or 25% or less. Therefore, a preferred range is 5-35%, 8-32%, etc.

[0041] The amount of the dicarboxylic acid ester (B) of the present invention is not particularly limited as long as the above ratio is satisfied, but preferred lower limits of the amount include 0.2% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.8% by mass or more, 1.0% by mass or more, or 1.5% by mass or more, relative to the total amount of the cosmetic composition, and preferred upper limits include 15% by mass or less, 10% by mass or less, or 6% by mass or less. Therefore, the range of the amount can be 0.2 to 15% by mass or 0.3 to 10% by mass. If the amount of component (B) is less than 0.2% by mass, the effect of improving UV protection may not be easily felt.

[0042] In addition to components (A) to (C) above, the sunscreen cosmetic composition of the present invention may further contain polyoxyalkylene / polyoxyethylene copolymer dialkyl ether. Polyoxyalkylene / polyoxyethylene copolymer dialkyl ether is commonly used as a humectant in cosmetics. In the present invention, the inclusion of polyoxyalkylene / polyoxyethylene copolymer dialkyl ether tends to enhance the effect of the present invention, which is to improve the UV protection capacity of the UV absorber. Furthermore, in addition to components (A) to (C) of the present invention, the inclusion of polyoxyalkylene / polyoxyethylene copolymer dialkyl ether tends to increase the rate of improvement of the thermoboost effect. Hereinafter, polyethylene glycol may be abbreviated as "PEG" and polypropylene glycol as "PPG". Specific examples of polyoxyalkylene-polyoxyethylene copolymer dialkyl ethers include PEG / PPG-9 / 2 dimethyl ether, PEG / PPG-17 / 4 dimethyl ether, PEG / PPG-14 / 7 dimethyl ether, PEG / PPG-11 / 9 dimethyl ether, PEG / PPG-55 / 28 dimethyl ether, PEG / PPG-36 / 41 dimethyl ether, PEG / PPG-6 / 3 dimethyl ether, PEG / PPG-8 / 4 dimethyl ether, PEG / PPG-6 / 11 dimethyl ether, and PEG / PPG-14 / 27 dimethyl ether. Among these, PEG / PPG-9 / 2 dimethyl ether is preferred. The amount of polyoxyalkylene-polyoxyethylene copolymer dialkyl ether blended is preferably 1 to 30% by mass, 2 to 28% by mass, 3 to 25% by mass, 4 to 23% by mass, or 5 to 20% by mass, based on the total amount of the cosmetic.

[0043] In addition to the above components, other optional components that are usually used in external skin preparations such as cosmetics and pharmaceuticals may be appropriately blended as needed within a range that does not impair the object and effects of the present invention. Examples of other optional components include, for example, oils other than the component (A), oil phase thickeners, surfactants, water phase thickeners, humectants, lower alcohols having 5 or less carbon atoms, neutralizing agents, ultraviolet scattering agents, powders such as extender pigments, dispersants, color materials, pigments, various drugs, various extracts, chelating agents, antioxidants (for example, tocopherol), preservatives (for example, phenoxyethanol), stabilizers (for example, dibutylhydroxytoluene (BHT)), fragrances, and essential oils, etc., can be appropriately blended as needed.

[0044] The oil other than the component (A) is not particularly limited as long as it is an oil usually blended in cosmetics, and examples include hydrocarbon oils, higher alcohols having 8 to 20 carbon atoms, ester oils, fatty acids, fats and oils, waxes, volatile and non-volatile silicone oils, etc.

[0045] When preparing the cosmetic composition according to the present invention as an emulsified cosmetic composition, a surfactant may be added. The surfactant is not particularly limited, and a lipophilic or hydrophilic surfactant can be appropriately selected depending on the desired emulsified cosmetic composition, such as a water-in-oil type or an oil-in-water type. As a lipophilic surfactant, it is preferable to use a surfactant with an HLB of less than 7, and as a hydrophilic surfactant, it is preferable to use a surfactant with an HLB of 7 or more. Examples of surfactants with an HLB of less than 7 include silicone-based surfactants such as polyether-modified silicones (e.g., PEG-10 dimethicone and PEG-9 polydimethylsiloxyethyl dimethicone), cationic surfactants such as distearyldimonium chloride, glycerin fatty acid esters (e.g., glyceryl monoisostearate, glyceryl sesquiisostearate, glyceryl monooleate, glyceryl dioleate, and glyceryl sesquioleate), polyglycerin fatty acid esters (e.g., polyglyceryl-2 diisostearate, diglyceryl monoisostearate, diglyceryl diisostearate, and diglyceryl dioleate), and sorbitan fatty acid esters (e.g., sorbitan monooleate, sorbitan monostearate, sorbitan tristearate, sorbitan trioleate, sorbitan isostearate, sorbitan sesquiisostearate, and sorbitan sesquioleate), and nonionic surfactants. Examples of surfactants with an HLB of 7 or higher include nonionic surfactants such as polyoxyethylene hydrogenated castor oil (e.g., PEG-60 hydrogenated castor oil), polyoxyethylene polyhydric alcohol fatty acid esters (e.g., PEG-3 glyceryl monoisostearate and PEG-8 glyceryl monoisostearate), and polyoxyethylene sorbitan fatty acid esters (e.g., polysorbate 60).

[0046] As the humectant, examples include 1,3 - butylene glycol, polyethylene glycol (PEG), propylene glycol, dipropylene glycol, hexylene glycol, glycerin, diglycerin, xylitol, maltitol, maltose, D - mannitol, and the like. However, the cosmetic according to the present invention does not necessarily need to contain a monoester of cyclohexanedicarboxylic acid such as cholesteryl 1,2 - cyclohexanedicarboxylate and cholesterol.

[0047] When a powder component is blended in the cosmetic of the present invention, a dispersant may be blended. The dispersant is not particularly limited and is appropriately selected from those usually blended in cosmetics. Examples include polyglycerol fatty acid esters having three or more glycerin molecules (for example, polyglyceryl - 6 polyricinoleate and polyglyceryl - 6 polyhydroxystearate) and long - chain fatty acids (for example, isostearic acid). However, the cosmetic according to the present invention does not necessarily need to contain decaglyceryl pentastearate, hexaglyceryl pentastearate, decaglyceryl pentaisostearate, and decaglyceryl tristearate.

[0048] The cosmetic of the present invention can be appropriately manufactured using a conventionally used method according to the form to be prepared. For example, when preparing an emulsified cosmetic, the component (A) and other oily components are mixed to prepare an oil - phase part, and separately, the component (B) and the component (C) and other aqueous components are mixed to prepare an aqueous - phase part, and the oil - phase part and the aqueous - phase part are stirred and emulsified with a homomixer or the like to be manufactured. The component (B) of the present invention can be appropriately mixed as an oily component or as an aqueous component.

[0049] The form of the cosmetic of the present invention is not particularly limited, and any form such as lotion, emulsion, cream, gel, and essence (beauty liquid), which have been conventionally used in cosmetics, can be widely applied.

[0050] The cosmetic of the present invention is suitable for providing as a lotion or the like having a sun - blocking effect, in addition to sun - blocking cream, sun - blocking emulsion, sun - blocking lotion, and the like.

[0051] The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, the amount of each component is expressed as a mass percentage of the system in which it is incorporated. Before describing each example in detail, the evaluation method used will be explained.

[0052] 1. Measurement of the cumulative absorbance (Abs) value. 2 mg / cm³ of the cosmetic (sample) for each example is added to the measurement plate (S plate) (5 x 5 cm V-groove PMMA plate, SPFMASTER-PA01). ２ The sample was dropped in the specified amount, spread with a finger for 60 seconds, and dried for 15 minutes. The absorbance of the formed coating was then measured using a U-4100 self-recording spectrophotometer (Hitachi, Ltd.). An uncoated plate was used as a control. The absorbance (Abs) was calculated using the following formula, and the measured values ​​from 280 nm to 400 nm were integrated to obtain the integrated absorbance value. Abs = -log(T / To) T: transmittance of the sample, To: transmittance of the uncoated plate

[0053] From the cumulative absorbance values ​​of the obtained samples, the improvement rate of UV protection was calculated using the following formula, with the sample without the dicarboxylic acid ester of the present invention (referred to as the "reference sample" in the table) as the reference: [Improvement rate of UV protection (%)] = [Cumulative absorbance value of the sample] / [Cumulative absorbance value of the reference sample] × 100 If the improvement rate exceeds 100%, it is evaluated that an improvement in UV protection has occurred.

[0054] 2. Measurement of the rate of change in UV protection due to heat. 2 mg / cm³ of the cosmetic (sample) for each example was added to the measurement plate (S plate) (5 x 5 cm V-groove PMMA plate, SPFMASTER-PA01). ２The sample was dropped in the specified amount, applied with a finger for 60 seconds, and dried for 15 minutes. The absorbance of the formed coating was then measured using a U-4100 self-recording spectrophotometer (Hitachi, Ltd.). An uncoated plate was used as a control. The absorbance (Abs) was calculated using the following formula, and the measured values ​​from 280 nm to 400 nm were integrated to obtain the integrated absorbance value. Abs = -log(T / To) T: transmittance of the sample, To: transmittance of the uncoated plate Next, the plate with the coating was placed in a constant temperature bath and subjected to a heat treatment at 30°C or 37°C for 30 minutes. The integrated absorbance value was then calculated in the same manner as above. For each sample, the rate of change in absorbance before and after heat irradiation (thermal change rate) was calculated according to the following formula. The rate of change in heat (%) = [(integrated absorbance after heat irradiation) / (integrated absorbance before heat irradiation)] × 100. When the rate of change in heat exceeds 100%, it is evaluated that an improvement in ultraviolet protection has occurred.

[0055] 3. Water-in-Oil Emulsified Sunscreen Cosmetics Water-in-oil emulsion sunscreen cosmetics having the compositions listed in Tables 1 to 3 below were prepared by conventional methods. Specifically, powder was dispersed in a mixture of oily components using a homomixer, and then a well-mixed aqueous component was added to obtain the cosmetic. The UV protection capacity of the prepared cosmetic was measured according to the evaluation method described above. The results are shown in the table.

[0056] *1: SA-Talc JA-68R (manufactured by Miyoshi Chemical Co., Ltd.) *2: SA-SB-Silica (manufactured by Miyoshi Chemical Co., Ltd.)

[0057]

[0058]

[0059] As shown in Tables 1 to 3, the incorporation of (B) dicarboxylic acid ester of the present invention resulted in an improvement in UV protection. Furthermore, a higher mass ratio of (B) dicarboxylic acid ester to (C) water ((B) / (C)) resulted in a higher improvement. In addition, a comparison between Examples 4 and 5, which included octocrylene as (A) UV absorber, and Examples 8 and 9, which did not include octocrylene as (A) UV absorber, showed that the improvement in UV protection was higher when octocrylene was included.

[0060] 4. Oil-in-water emulsion sunscreen cosmetic A water-in-water emulsion sunscreen cosmetic having the composition listed in Table 4 below was prepared by a conventional method.

[0061]

[0062] As shown in Table 4, even in the case of oil-in-water emulsion cosmetics, the UV protection was improved by incorporating the (B) dicarboxylic acid ester of the present invention, similar to the water-in-oil emulsion cosmetics.

[0063] 5. Change in UV protection due to heat. Water-in-oil emulsion sunscreen cosmetics having the compositions listed in Table 5 below were prepared by conventional methods, and the change in UV protection after irradiating the coated film with heat at 30°C or 37°C was measured.

[0064]

[0065] It was confirmed that the addition of (B) dicarboxylic acid ester produced a thermoboost effect whether PEG / PPG-9 / 2 dimethyl ether was not included (Example 15) or included (Example 16). Furthermore, it was shown that this thermoboost effect was equivalent to or better than that obtained when the temperature of heat applied to the coating film was 30°C, compared to 37°C. In addition, it was shown that the rate of improvement of the thermoboost effect tended to increase when PEG / PPG-9 / 2 dimethyl ether was included in addition to components (A) to (C) of the present invention.

Claims

1. A sunscreen cosmetic comprising (A) an ultraviolet absorber, (B) a dicarboxylic acid ester, and (C) water, wherein the ratio of (B) dicarboxylic acid ester to (C) water ((B) / (C)) is 1.8% or more by mass.

2. The cosmetic composition according to claim 1, wherein component (A) comprises octocrylene.

3. The cosmetic composition according to claim 1, wherein the amount of component (B) is 0.2% by mass or more relative to the total amount of the cosmetic composition.

4. The cosmetic composition according to claim 1, wherein component (B) comprises a dicarboxylic acid ester consisting of a dicarboxylic acid having 4 to 24 carbon atoms and polyglycerin.

5. The cosmetic composition according to claim 1, wherein component (B) comprises one or more selected from (eicosanedioic acid / tetradecanedioic acid) polyglyceryl-10 and cyclohexane-1,4-dicarboxylic acid bisethoxydiglycol.

6. The cosmetic composition according to claim 1, wherein the cosmetic composition is an oil-in-water emulsion cosmetic composition.

7. The cosmetic composition according to claim 1, wherein the cosmetic composition is a water-in-oil emulsion cosmetic composition, and the ratio of (B) dicarboxylic acid ester to (C) water ((B) / (C)) is 5% or more by mass.

8. A method for protecting the skin from ultraviolet rays, comprising applying a cosmetic containing (A) an ultraviolet absorber, (B) a dicarboxylic acid ester, and (C) water to the skin, and irradiating the applied film with heat of 30°C or higher.

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