Method for forming ultraviolet protection coating film

Abstract

To provide a method for forming an ultraviolet protection coating film with good usability and durability, on the skin, the coating film being homogeneous and having excellent UV protection ability and durability.SOLUTION: A method for forming an ultraviolet protection coating on skin comprises: a step (1) of applying a composition containing an ultraviolet protection agent to the skin; and a step (2) of transferring a nanofiber sheet, which is formed on a substrate and in which a nanofiber structure is formed by a water-insoluble polymer, to the skin after application in step (1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for forming an ultraviolet ray protective coating on skin. [Background technology]

[0002] Conventionally, sunscreen cosmetics contain ultraviolet protection agents in order to block ultraviolet radiation from reaching the skin and obtain a high SPF (Sun Protection Factor) value. However, cosmetics containing these UV protection agents have the disadvantage of being poorly water-resistant and sweat-resistant, and disappearing from the skin due to sweat, etc. In addition, since there are many irregularities on the skin, the SPF value is low in areas where the coating film is thin. Furthermore, there is also the problem that the coating film disappears when it comes into contact with clothing, fingers, or other skin.

[0003] In response to this, various methods for forming a coating by electrostatic spraying are known. For example, Patent Document 1 describes a method for treating skin that includes electrostatically spraying a composition such as a cosmetic foundation onto the skin. However, the coating formed by electrostatic spraying described in Patent Document 1 does not adhere sufficiently to the skin, and the color of the foundation transfers to clothing or the skin when it comes into contact with the skin. Therefore, the applicant has reported a method for producing an ultraviolet protective coating on skin, which is characterized by having a step of applying a composition containing an ultraviolet protection agent to the skin and a step of electrostatically spraying a composition containing component (a) and component (b) directly onto the skin to form a coating on the skin, in this order or in the reverse order (Patent Document 2). (a) one or more volatile substances selected from water, alcohols, and ketones; (b) A polymer having film-forming ability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-104211 A [Patent Document 2] JP 2018-177795 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a coating is formed on the skin by applying a composition containing an ultraviolet protection agent to the skin and then electrostatically spraying a composition for spraying directly onto the skin, the basis weight may not be constant in the area where the ultraviolet protection agent-containing composition is applied, and the coating may not have sufficient homogeneity as a whole. This poses the problem that a uniform ultraviolet protection effect may not be obtained over the entire application area. Thus, the present invention provides a method for forming an ultraviolet protective coating on the skin, which is a homogeneous coating having excellent ultraviolet protective ability and durability, and is easy to use and durable. [Means for solving the problem]

[0006] Therefore, the present inventors discovered that by applying a composition containing an ultraviolet protection agent onto the skin, and then transferring a nanofiber sheet, which is preformed on a substrate and has a nanofiber structure formed by a water-insoluble polymer, onto the skin after application of the composition, the ultraviolet protection agent can be uniformly distributed onto the skin with a simple operation, and a homogeneous and long-lasting ultraviolet protection effect can be obtained, thus completing the present invention.Furthermore, the inventors discovered that by using an adhesive polymer in addition to a water-insoluble polymer as a component of the nanofiber sheet, the transferability, compatibility, appearance (transparency), and film durability of the nanofiber sheet can be improved even under high temperature or high humidity conditions.

[0007] That is, the present invention relates to a method for treating a skin condition comprising the steps of: (1) applying a composition containing an ultraviolet protection agent to the skin; The present invention provides a method for forming an ultraviolet protective coating on skin, comprising: a step (2) of transferring, to the skin after step (1) application, a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer. The present invention also provides a kit for forming an ultraviolet ray protective coating on skin, comprising a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer, and a composition containing an ultraviolet ray protective agent. Effect of the Invention

[0008] According to the present invention, the UV protection agent can be uniformly distributed on the skin with a simple operation, and a uniform and long-lasting UV protection effect can be obtained. Furthermore, when an adhesive polymer is used in addition to a water-insoluble polymer as a component of the nanofiber sheet, the transferability, compatibility, appearance (transparency), and film durability of the nanofiber sheet are good even under high temperature or high humidity conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] One aspect of the present invention is (1) applying a composition containing an ultraviolet protection agent to the skin; A step (2) of transferring the nanofiber sheet formed on the substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer, to the skin after application in the step (1); The method for forming an ultraviolet ray protective coating on the skin comprises the steps of: Steps (1) and (2) will be described below.

[0010] Step (1) is a step of applying an ultraviolet protection agent-containing composition (hereinafter also referred to as a UV composition) to the skin. Examples of ultraviolet protection agents used in the UV composition include ultraviolet scattering agents and ultraviolet absorbing agents. Among these, the ultraviolet absorbing agent is particularly preferably an organic ultraviolet absorbing agent, and examples of the organic ultraviolet absorbing agent that are oil-soluble include a benzoic acid-based ultraviolet absorbing agent, an anthranilic acid-based ultraviolet absorbing agent, a salicylic acid-based ultraviolet absorbing agent, a cinnamic acid-based ultraviolet absorbing agent, a benzophenone-based ultraviolet absorbing agent, and a triazine-based ultraviolet absorbing agent.

[0011] Benzoic acid-based ultraviolet absorbers include para-aminobenzoic acid (hereinafter abbreviated as PABA), glyceryl PABA, ethyl dihydroxypropyl PABA, N-ethoxylate PABA ethyl ester, N-dimethyl PABA ethyl ester, N-dimethyl PABA butyl ester, N-dimethyl PABA amyl ester, octyl dimethyl PABA, diethylaminohydroxybenzoyl hexyl benzoate, etc. From the viewpoint of enhancing the ultraviolet absorbing effect while suppressing stickiness, para-aminobenzoic acid and diethylaminohydroxybenzoyl hexyl benzoate are preferred, and diethylaminohydroxybenzoyl hexyl benzoate is more preferred. Examples of anthranilic acid-based ultraviolet absorbers include homomenthyl-N-acetylanthranilate. Examples of salicylic acid-based ultraviolet absorbers include amyl salicylate, menthyl salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, and p-isopropanol phenyl salicylate. Examples of cinnamic acid-based ultraviolet absorbers include ethyl-4-isopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate, methyl-2,4-diisopropyl cinnamate, propyl-p-methoxy cinnamate, isopropyl-p-methoxy cinnamate, isoamyl-p-methoxy cinnamate, 2-ethylhexyl-p-methoxy cinnamate, 2-ethoxyethyl-p-methoxy cinnamate, cyclohexyl-p-methoxy cinnamate, ethyl-α-cyano-β-phenyl cinnamate, 2-ethylhexyl-α-cyano-β-phenyl cinnamate, glyceryl mono-2-ethylhexanoyl di-para-methoxy cinnamate, etc. Among these, from the viewpoint of enhancing ultraviolet absorbing effect, 2-ethylhexyl-p-methoxy cinnamate is more preferable. Examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenylbenzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, and 4-hydroxy-3-carboxybenzophenone. As the triazine-based ultraviolet absorber, from the viewpoint of enhancing the ultraviolet absorbing effect, one or more selected from 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine, 2,4-bis-[{4-(2-ethylhexyloxy)-2-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine, and the like are preferable. Other examples include 3-(4'-methylbenzylidene)-dl-camphor, 3-benzylidene-dl-camphor, urocanic acid ethyl ester, 2-phenyl-5-methylbenzoxazole, 2,2'-hydroxy-5-methylphenylbenzotriazole, 2-(2'-hydroxy-5-t-octylphenyl)benzotriazole, dibenzalazine, dianisoylmethane, 4-methoxy-4'-t-butyldibenzoylmethane, 5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one, benzene bis-1,3-diketone derivatives described in JP-A-2-212579, and benzoyl pinacolone derivatives described in JP-A-3-220153.

[0012] From the viewpoint of enhancing the ultraviolet protection effect, the ultraviolet protection agent preferably contains an ultraviolet absorber, and in particular, it is preferable that the ultraviolet protection agent contains at least one selected from benzoic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, cinnamic acid-based ultraviolet absorbers, and triazine-based ultraviolet absorbers, it is more preferable that the ultraviolet protection agent contains at least one selected from benzoic acid-based ultraviolet absorbers, cinnamic acid-based ultraviolet absorbers, and triazine-based ultraviolet absorbers, and it is even more preferable that the ultraviolet protection agent contains at least two selected from benzoic acid-based ultraviolet absorbers, cinnamic acid-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

[0013] As the ultraviolet scattering agent, fine particle metal oxide or fine particle metal oxide treated to be hydrophobized is preferable. As the fine metal oxide particles, from the viewpoint of availability, one or more fine metal oxide particles selected from zinc oxide, titanium oxide, cerium oxide, iron oxide, and chromium oxide are preferred. Among these fine metal oxide particles, from the viewpoint of ultraviolet protection effect, one or more fine metal oxide particles selected from zinc oxide, titanium oxide, and cerium oxide are preferred, and one or more fine metal oxide particles selected from zinc oxide and titanium oxide are more preferred. In addition, these fine metal oxide particles can contain trace elements with a valence of +2 or more, and metals such as iron, zirconium, calcium, manganese, magnesium, and yttrium can be contained alone or in combination of two or more. From the viewpoint of ultraviolet protection effect, it is preferable to use at least fine titanium oxide as the fine metal oxide particle, and it is more preferable to use only fine titanium oxide particle or to use a combination of fine titanium oxide particle and fine zinc oxide particle.

[0014] The shape of the above-mentioned "fine particle metal oxide" is not particularly limited, and examples thereof include spherical, plate-like, rod-like, spindle-like, needle-like, and irregular shapes. The average particle size of the "fine particle metal oxide" is preferably 0.01 μm or more, more preferably 0.012 μm or more, even more preferably 0.015 μm or more, and is preferably 1 μm or less, more preferably 0.8 μm or less, and even more preferably 0.5 μm or less. The specific range of the average particle size is preferably 0.01 μm or more and 1 μm or less, more preferably 0.012 μm or more and 0.8 μm or less, and particularly preferably 0.015 μm or more and 0.5 μm or less. By setting the average particle size in such a range, the ultraviolet protection effect and dispersion stability can be improved. The average particle size of the fine particle metal oxide means the average particle size measured by a laser diffraction / scattering method.

[0015] As the fine zinc oxide particles, for example, FINEX-25, FINEX-30, FINEX-50, FINEX-75 (manufactured by Sakai Chemical Industry Co., Ltd.), MZ300 series, MZ500 series, MZ700 series (manufactured by Teika Co., Ltd.), ZnO-350 (manufactured by Sumitomo Osaka Cement Co., Ltd.), etc. are commercially available. As the fine titanium oxide particles, for example, TTO-55 series, TTO-51 series (manufactured by Ishihara Sangyo Kaisha), JR series, JA series (manufactured by Teika Co., Ltd.), etc. are commercially available. As the fine cerium oxide particles, for example, high purity cerium sold by Nikki Co., Ltd. or Seimi Chemical Co., Ltd. may be used.

[0016] The hydrophobization treatment of the above-mentioned fine particle metal oxide may be carried out using a known surface treatment agent for hydrophobization, and examples thereof include fluorine compound treatment, silicone treatment, silicone resin treatment, pendant treatment, silane coupling agent treatment, titanium coupling agent treatment, oil treatment, N-acylated lysine treatment, polyacrylic acid treatment, metal soap treatment, amino acid treatment, inorganic compound treatment, plasma treatment, mechanochemical treatment, silane compound treatment, and silazane compound treatment. Of these treatments, treatment with silicone or silicone resin, treatment with a silane compound or silazane compound, and treatment with a metal soap such as aluminum stearate, aluminum isostearate, or aluminum laurate are preferred from the standpoint of dispersion stability, etc.

[0017] The ultraviolet protection agent can be used alone or in combination of two or more, and the combination and content are determined according to the ultraviolet protection effect. From the viewpoint of further expressing the ultraviolet protection effect, the content of the ultraviolet protection agent in the UV composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and even more preferably 10% by mass or more. In addition, from the viewpoint of suppressing stickiness and imparting a smooth feeling, the content of the ultraviolet protection agent in the UV composition is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 18% by mass or less.

[0018] The UV composition may contain an oil other than the UV protection agent that is liquid at 20°C for the purpose of dissolving the UV protection agent and for the purpose of improving the adhesion and durability to the skin of the coating formed from the transferred nanofiber sheet and UV composition.

[0019] Examples of oils that are liquid at 20°C include linear or branched hydrocarbon oils such as liquid paraffin, light isoparaffin, liquid isoparaffin, squalane, and squalene; vegetable oils such as jojoba oil and olive oil, animal oils such as liquid lanolin, ester oils such as monoalcohol fatty acid esters and polyhydric alcohol fatty acid esters; and silicone oils such as dimethylpolysiloxane, dimethylcyclopolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and higher alcohol-modified organopolysiloxane. Among these, from the viewpoint of usability such as smoothness during application, polar oils such as hydrocarbon oils, ester oils, vegetable oils containing triglycerides, and silicone oils are preferred, and one or more selected from hydrocarbon oils, ester oils, and silicone oils are more preferred. In addition, one or more liquid oils selected from these can be used in combination.

[0020] Examples of the hydrocarbon oil include liquid paraffin, squalane, squalene, n-octane, n-heptane, cyclohexane, light isoparaffin, liquid isoparaffin, etc., and liquid paraffin and squalane are preferred from the viewpoint of usability. In addition, from the viewpoint of adhering the coating formed by the transferred nanofiber sheet and the UV composition to the skin, the viscosity of the hydrocarbon oil at 30°C is preferably 10 mPa·s or more, more preferably 30 mPa·s or more. From this viewpoint, the total content of isododecane, isohexadecane, and hydrogenated polyisobutene, which have a viscosity of less than 10 mPa·s at 30°C, in the UV composition is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, and may not be contained. Similarly, from the viewpoint of ensuring that the coating formed by the transferred nanofiber sheet and UV composition adheres closely to the skin, the viscosity of the ester oil and silicone oil at 30°C is preferably 10 mPa s or more, and more preferably 30 mPa s or more. The viscosity here is measured at 30° C. using a BM type viscometer (manufactured by Tokimec Co., Ltd., measurement conditions: rotor No. 1, 60 rpm, 1 minute). From the same viewpoint, the total content of ether oils such as cetyl-1,3-dimethylbutyl ether, dicapryl ether, dilauryl ether, diisostearyl ether, etc. in the UV composition is preferably 10 mass% or less, more preferably 5 mass% or less, and even more preferably 1 mass% or less.

[0021] The ester oil includes esters of linear or branched fatty acids and linear or branched alcohols or polyhydric alcohols. Specifically, isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearyl acid, ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, pentaerythritol tetra-2-ethylhexanoate, glyceryl tri-2-ethylhexanoate , Trimethylolpropane Triisostearate, Cetyl 2-Ethylhexanoate, 2-Ethylhexyl Palmitate, Diethylhexyl Naphthalenedicarboxylate, Benzoate (C12-15) Alkyl, Cetearyl Isononanoate, Tri(Caprylic / Capric) Glycerin, Butylene Glycol (Dicaprylic / Capric), Glyceryl Trilaurate, Glyceryl Trimyristate, Tripalmitic Acid Examples of suitable glyceryl are glyceryl triisostearate, glyceryl tri-2-heptylundecanoate, glyceryl tribehenate, tricoconut oil fatty acid glyceryl, castor oil fatty acid methyl ester, oleyl oleate, 2-heptylundecyl palmitate, diisobutyl adipate, N-lauroyl-L-glutamic acid-2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, di-2-ethylhexyl succinate, triethyl citrate, and tripropylene glycol dipivalate.

[0022] Among these, from the viewpoint of adhering the coating formed by the transferred nanofiber sheet and UV composition to the skin and from the viewpoint of excellent sensation when applied to the skin, octyldodecyl myristate, myristyl myristate, isocetyl stearate, isocetyl isostearate, cetearyl isononanoate, diisobutyl adipate, di-2-ethylhexyl sebacate, isopropyl myristate, isopropyl palmitate, diisostearyl malate, neopentyl glycol dicaprate, and alkyl benzoate (carbon number 12 to 15) are selected. At least one selected from the group consisting of isopropyl myristate, isopropyl palmitate, diisostearyl malate, neopentyl glycol dicaprate, alkyl benzoate (having 12 to 15 carbon atoms), and tri(caprylic acid / capric acid)glycerin is preferred, at least one selected from the group consisting of neopentyl glycol dicaprate, alkyl benzoate (having 12 to 15 carbon atoms), and tri(caprylic acid / capric acid)glycerin is more preferred, and at least one selected from the group consisting of neopentyl glycol dicaprate, alkyl benzoate (having 12 to 15 carbon atoms), and tri(caprylic acid / capric acid)glycerin is even more preferred.

[0023] As the triglyceride, fatty acid triglycerides are preferred, and examples thereof include olive oil, jojoba oil, macadamia nut oil, medfoam oil, castor oil, safflower oil, sunflower oil, avocado oil, canola oil, apricot kernel oil, rice germ oil, and rice bran oil.

[0024] Examples of silicone oils include dimethylpolysiloxane, methylcyclopolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and higher alcohol-modified organopolysiloxane. The kinetic viscosity of the silicone oil at 25°C is set to 3 mm from the viewpoint of adhering the transferred nanofiber sheet and the coating formed by the UV composition to the skin. 2 / s is preferred, 4mm 2 / s is more preferable, 5mm 2 / s or more is more preferable, and 30 mm 2 / s or less is preferable, 20 mm 2 / s or less is preferable, and 10 mm 2 / s or less is even more preferable. Among these, it is preferable that the composition contains methylpolysiloxane from the viewpoint of adhering the coating formed of the transferred nanofiber sheet and UV composition to the skin.

[0025] The content of the liquid oil in the UV composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 5% by mass or more. Also, it is preferably 90% by mass or less. The content of the liquid oil in the UV composition is preferably 0.1% by mass or more and 90% by mass or less, more preferably 0.5% by mass or more and 70% by mass or less, and even more preferably 50% by mass or less.

[0026] The UV composition may further contain water and polyol. When the UV composition contains water or polyol, the form of the UV composition includes emulsions (O / W emulsion, W / O emulsion) and the like.

[0027] In the case where a polyol is contained, examples of the polyol include alkylene glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, etc.; polyalkylene glycols such as diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, etc.; glycerins such as glycerin, diglycerin, triglycerin, etc. Among these, from the viewpoint of usability such as smoothness, one or more selected from ethylene glycol, propylene glycol, 1,3-butanediol, dipropylene glycol, polyethylene glycol, glycerin, and diglycerin are preferred, further one or more selected from propylene glycol, 1,3-butanediol, and glycerin are more preferred, and one or two selected from propylene glycol and 1,3-butanediol are even more preferred.

[0028] The UV composition contains an ultraviolet protection agent and the above-mentioned components, and can be in the form of an oil composition, a water-in-oil type emulsion composition, an oil-in-water type emulsion composition, etc. The form can be liquid, milky, creamy, paste, solid, multi-layered, etc. Ingredients other than the ultraviolet protection agent that can be blended in the UV composition include the above-mentioned liquid oil, as well as solid oil, emulsifier, water, polyol, coloring pigment, extender pigment, dye, fragrance, antioxidant, preservative, and various vitamins.

[0029] In particular, when the UV composition contains polar oil, the composition preferably contains water and polar oil from the viewpoint of enhancing the adhesion of the film formed by the transferred nanofiber sheet and the UV composition to the skin, and preferably contains 40% by mass or more and 100% by mass or less of water and polar oil in total.In addition, from the viewpoint of stability, the UV composition may contain a surfactant, a polymer, or a thickener, and from the viewpoint of improving the adhesion to the skin and the moisturizing performance of the film, it may contain an oil agent that is solid at 30°C, such as Vaseline, cetanol, stearyl alcohol, or ceramide. Similarly, when the UV composition contains a polyol, the composition preferably contains water and a polyol from the viewpoint of enhancing the adhesion of the transferred nanofiber sheet and the coating formed by the UV composition to the skin, and preferably contains 40% by mass or more and 100% by mass or less in total of water and polyol. From the viewpoint of stability, the UV composition may contain a surfactant, a polymer, or a thickener, and from the viewpoint of improving the adhesion to the skin and the moisturizing performance of the coating, it may contain an oil agent that is solid at 30°C, such as petrolatum, cetanol, stearyl alcohol, or ceramide.

[0030] The UV composition preferably has a viscosity of about 100,000 mPa·s or less, preferably 30,000 mPa·s or less, more preferably about 10,000 mPa·s or less at 25° C. in terms of improving adhesion between the transferred nanofiber sheet and the coating formed by the UV composition. The viscosity of the UV composition is measured using a B-type viscometer (Toki Sangyo Co., Ltd., TVB-10 model, measurement conditions: rotor No. 1, 60 rpm, 1 minute).

[0031] To apply the UV composition to the skin, a method for applying a normal cosmetic to the skin can be used. For example, the composition can be applied to the skin by a method such as finger application, and a step of spreading the composition can be included, so that the composition can be blended with the skin and a thin layer of the composition can be formed. The step of spreading the UV composition can be, for example, a method such as rubbing with the user's own finger or a tool such as an applicator. Alternatively, the UV composition can be sprayed onto the skin by a normal means to form a thin layer of the composition. In this case, a separate spreading step is not particularly necessary, but the operation of spreading after spraying is not prevented.

[0032] The amount of the UV composition applied to the skin should be a necessary and sufficient amount to improve the UV protection effect and the adhesion between the transferred nanofiber sheet and the coating formed by the UV composition. From the viewpoint of improving the UV protection effect and durability, the amount of the UV composition applied to the skin is preferably such that the basis weight of the composition after application is 1 g / m 2 More preferably, 3 g / m 2 More preferably, 5 g / m 2 More preferably, 10 g / m 2 From the viewpoint of the film feel, the amount is preferably 85 g / m 2 More preferably, it is 60 g / m 2 More preferably, it is 40 g / m or less. 2 and even more preferably 35 g / m 2 For example, the amount of UV composition applied to the skin is preferably such that the basis weight of the composition after application is 5 g / m 2 More than 40g / m 2 Less than 10 g / m 2 More than 35g / m 2 The quantity is as follows:

[0033] Step (2) is a step of transferring the nanofiber sheet formed on the substrate, in which the nanofiber structure is formed by a water-insoluble polymer, to the skin after application in step (1). In the present invention, the nanofiber sheet is a nanofiber sheet that is formed in advance on a substrate, and is a nanofiber sheet formed by depositing nanofibers that contain a water-insoluble polymer as a main component.

[0034] A nanofiber sheet is a sheet formed of nanofibers. The nanofiber sheet is preferably composed only of nanofibers, but this does not preclude the nanofiber sheet from containing other components in addition to nanofibers. The thickness of nanofibers, expressed as a circle equivalent diameter, is generally 10 to 3000 nm, particularly 10 to 1000 nm. The thickness of nanofibers can be measured, for example, by scanning electron microscope (SEM) observation. Specifically, the nanofibers are observed at a magnification of 10,000 times by SEM observation, defects (lumps of nanofibers, intersections of nanofibers, droplets) are removed from the two-dimensional image, 10 nanofibers are arbitrarily selected, a line perpendicular to the longitudinal direction of the nanofibers is drawn, and the diameter is directly read to measure the thickness. The length of the nanofiber is not particularly limited, but is preferably 100 times or more the diameter. The nanofiber sheet can be obtained by various known methods such as electrospinning and melting (melt blowing), and is preferably obtained by electrospinning or melt blowing on a substrate. When produced by the electrospinning method, the nanofibers are deposited in a sheet-like structure, and such a structure in which the nanofibers are deposited is more preferable in terms of adhesion and homogeneity between the transferred nanofiber sheet and the coating formed by the UV composition. When produced by the melt blowing method, the nanofibers are also deposited in a sheet-like structure, and are preferable in terms of production costs.

[0035] When the nanofiber sheet is used by being transferred to the skin, from the viewpoint of obtaining a good ultraviolet protection effect, the thickness of the nanofiber sheet is preferably 0.1 μm or more, more preferably 5.1 μm or more, and even more preferably 10 μm or more. Furthermore, when the nanofiber sheet is used by being transferred to the skin, from the viewpoint of making the transferred nanofiber sheet difficult to see (to make it transparent), the thickness of the nanofiber sheet is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 100 μm or less. The thickness of the nanofiber sheet is preferably 5.1 μm or more and 500 μm or less, more preferably 10 μm or more and 400 μm or less, and even more preferably 10 μm or more and 100 μm or less. The thickness of the nanofiber sheet is the maximum thickness measured by peeling off only the nanofiber sheet from the substrate and using a contact-type film thickness gauge (Mitutoyo Litematic VL-50A (R5 mm superhard spherical probe)). The load applied to the measurement object during measurement is 0.01 Pa.

[0036] The nanofiber sheet used in the present invention is a nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer, and is obtained by laminating nanofibers having a nanofiber structure formed by a water-insoluble polymer on a substrate. More specifically, it is preferably produced by forming a deposit of nanofibers on a substrate by electrospinning a volatile medium solution containing a water-insoluble polymer. Water-insoluble refers to a nanofiber sheet that has the property that, when 1 g of the nanofiber sheet is weighed out and immersed in 10 g of deionized water in an environment of 1 atmosphere and 23°C, after 24 hours, more than 0.5 g of the immersed nanofiber sheet does not dissolve, and preferably more than 0.8 g of the immersed nanofiber sheet does not dissolve.

[0037] The nanofiber sheet is formed by depositing nanofibers containing a fiber-formable polymer as a main component. From the viewpoint of making the nanofiber sheet water-insoluble, the nanofiber sheet preferably contains nanofibers containing a water-insoluble polymer as a main component as the fiber-formable polymer. Examples of water-insoluble polymers include fully saponified polyvinyl alcohol that can be insolubilized after nanofiber formation, partially saponified polyvinyl alcohol that can be crosslinked after nanofiber formation by using a crosslinking agent in combination, oxazoline-modified silicones such as poly(N-propanoylethyleneimine) graft-dimethylsiloxane / γ-aminopropylmethylsiloxane copolymers, zein (a major component of corn protein), polyester resins such as polylactic acid, polyethylene terephthalate resin, and polybutylene terephthalate resin, acrylic resins such as polyacrylonitrile resin and polymethacrylic acid resin, polystyrene resin, polyvinyl butyral resin, polyurethane resin, polyamide resins such as nylon, polyimide resin, polyamideimide resin, etc. These water-insoluble polymers can be used alone or in combination of two or more.

[0038] Of these water-insoluble polymers, from the viewpoint of obtaining a nanofiber sheet that has excellent transferability and can easily maintain good quality even in the usage environment, particularly in a hot and humid environment, it is preferable that the moisture absorption in a hot and humid environment (left to stand for 24 hours at 40°C and 90 RH%) is 1% or less, more preferably 0.9% or less. From the same viewpoint, it is preferable that the moisture absorption is 0.1% or more, more preferably 0.6% or more.

[0039] In this specification, the moisture absorption of a polymer in a hot and humid environment is measured by a constant rate method described below. 1 g of the polymer to be measured is placed in an incubator at 40°C and 90% RH (high temperature and humidity environment) for 24 hours to apply a high temperature and humidity load to the polymer to be measured. The weight of the polymer to be measured before the high temperature and humidity load is measured immediately after it is placed in an environment of 25°C and 50% RH for 1 minute is defined as the "initial weight", and the weight of the polymer to be measured after the high temperature and humidity load is measured immediately after it is taken out of the incubator and placed in an environment of 25°C and 50% RH for 1 minute is defined as the "weight after high temperature and humidity load". The moisture absorption of the polymer to be measured is calculated using the following formula (1). Moisture absorption = (weight after high temperature and humidity load - initial weight) / initial weight x 100 (%) ... (1) In this specification, unless otherwise specified, "hygroscopicity" means "hygroscopicity under a high temperature and high humidity environment."

[0040] Of the water-insoluble polymers, from the viewpoint of obtaining a nanofiber sheet that has excellent transferability and is easy to maintain good quality, it is more preferable to use one or more polymers selected from polyvinyl butyral resin, polyurethane resin, and polylactic acid, and it is even more preferable to use polyvinyl butyral resin.

[0041] When a nanofiber sheet is formed using only a water-insoluble polymer, the transferability is good, but the nanofiber sheet tends to have poor skin compatibility. On the other hand, when a water-soluble polymer is added to the nanofiber sheet in order to improve skin compatibility, the compatibility is improved, but the nanofiber sheet absorbs moisture, dissolves, and adheres to the substrate, making it difficult to transfer. In addition, such dissolution of the nanofiber sheet tends to occur particularly under conditions such as high temperature or high humidity, and there is room for improvement in nanofiber sheets that are transferred to the skin and used. Therefore, as a result of studies to develop a nanofiber sheet that has excellent transferability and good skin compatibility even when stored under conditions such as high temperature or high humidity, it was found that if an adhesive polymer is used in combination with the water-insoluble polymer that forms the nanofiber structure, the adhesive polymer contributes to the modification of the nanofiber surface, and a nanofiber sheet that has excellent transferability and good skin compatibility can be obtained even when stored under high temperature or high humidity conditions. As such an adhesive polymer, a polymer having a moisture absorption of more than 1% and not more than 40% in a high temperature and high humidity environment (left to stand for 24 hours at 40°C and 90% RH) is preferred. That is, from the viewpoint of good skin compatibility, excellent transferability, and reducing wrinkling of the nanofiber sheet attached to the skin and the inclusion of air bubbles, the moisture absorption is more than 1%, preferably 3% or more, more preferably 5% or more, and even more preferably 8% or more, and from the same viewpoint, it is 40% or less, preferably 32% or less, more preferably 29% or less, and even more preferably 18% or less. The moisture absorption of the adhesive polymer is more than 1% and not more than 40%, preferably 3% or more and not more than 32%, more preferably 5% or more and not more than 29%, and even more preferably 8% or more and not more than 18%.

[0042] The adhesive polymer may contain one or more polymers selected from polyvinylpyrrolidone, polyvinylpyrrolidone copolymers, polyalkylene glycols, and silicone structure-containing copolymers. From the viewpoint of improving the skin compatibility of the nanofiber sheet adhered to the skin and from the viewpoint of excellent transferability, it is preferable to use one or more polymers selected from polyvinylpyrrolidone copolymers and polyalkylene glycols.

[0043] Examples of polyvinylpyrrolidone copolymers include vinyl acetate-vinylpyrrolidone copolymer, vinylpyrrolidone-dimethylaminoethyl methacrylate copolymer diethyl sulfate, and vinylcaprolactam-vinylpyrrolidone-dimethylaminopropyl methacrylamide-methacryloylaminopropyl lauryldimonium chloride copolymer. From the viewpoints of improving the compatibility of the nanofiber sheet attached to the skin and of excellent transferability, it is preferable to use a vinyl acetate-vinylpyrrolidone copolymer. From the viewpoint of improving the compatibility of the nanofiber sheet with the skin, the content of one or more polymers selected from polyvinylpyrrolidone, polyvinylpyrrolidone copolymers, polyalkylene glycols, and silicone structure-containing copolymers relative to the total amount of adhesive polymers is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 95% by mass or more, and preferably 100% by mass or less.

[0044] Vinyl acetate-vinylpyrrolidone copolymer is a copolymer obtained by polymerization of vinyl acetate and vinylpyrrolidone, and has a structure based on vinyl acetate and a structure based on vinylpyrrolidone in the polymer. Here, assuming that the structure based on vinyl acetate is VP and the structure based on vinylpyrrolidone is VA, the ratio of VP to VA (VP:VA) in the vinyl acetate-vinylpyrrolidone copolymer in the present invention is preferably in the range of VP:VA=20:80 to 80:20, more preferably in the range of VP:VA=25:75 to 65:35, from the viewpoint of improving the compatibility of the nanofiber sheet attached to the skin and from the viewpoint of excellent transferability. The ratio in this item refers to the molar ratio, and the amount of remaining monomers relative to the charged monomer composition can be calculated by gas chromatography.

[0045] More specifically, the following commercially available products can be used as polyvinylpyrrolidone and copolymers of polyvinylpyrrolidone. Product name: Rubiscol K30 (BASF Ltd.) Product name: PVA / VA E735 (Ashland Japan Co., Ltd.) Product name: PVP / VA S-630 (Ashland Japan Co., Ltd.) Product name: PVA / VA E535 (Ashland Japan Co., Ltd.) Product name: PVA / VA E335 (Ashland Japan Co., Ltd.) Product name: Gafquat (registered trademark) 734 (Ashland Japan Co., Ltd.) Product name: Aquastyle300N (Ashland Japan Co., Ltd.)

[0046] Examples of polyalkylene glycols include polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol. From the viewpoint of improving the compatibility of the nanofiber sheet attached to the skin and from the viewpoint of excellent transferability, it is preferable to use polyoxyethylene polyoxypropylene glycol.

[0047] From the viewpoints of good skin compatibility, excellent transferability, and reducing wrinkling of the nanofiber sheet attached to the skin and the inclusion of air bubbles, the average number of moles of ethylene oxide added in polyoxyethylene polyoxypropylene glycol is preferably 5 to 200, more preferably 10 to 30. From the similar viewpoints, the average number of moles of propylene oxide added is preferably 5 to 100, more preferably 10 to 30. The average number of moles of ethylene oxide added can be calculated, for example, by the method described in "JIS K 0070-1992 7.1 Neutralization titration method," and the average number of moles of propylene oxide added can be determined using 1H-NMR.

[0048] As more specific examples, the following commercially available products can be used as the polyethylene glycol adduct. Product name: Pronon (registered trademark) 124P (NOF Corporation) Product name: Pronon (registered trademark) 237P (NOF Corporation) Product name: Pronon (registered trademark) 407P (NOF Corporation)

[0049] As more specific examples, the following commercially available products can be used as the silicone structure-containing copolymer. Product name: OS-88TE-E (Kao Corporation) Product name: Silicone KF-6011 (Shin-Etsu Chemical Co., Ltd.)

[0050] In addition, the following commercially available adhesive polymers can be used. Product name: Gantrez (registered trademark)-es225 (Ashland Japan Co., Ltd.)

[0051] In the nanofiber sheet used in the present invention, the content of the water-insoluble polymer is preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and even more preferably 68% by mass or more, from the viewpoints of good skin compatibility, excellent transferability, and reducing wrinkling of the nanofiber sheet attached to the skin and the inclusion of air bubbles, and from the same viewpoints, it is preferably 96% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and even more preferably 75% by mass or less. The content of the water-insoluble polymer is preferably 55% by mass or more and 96% by mass or less, more preferably 60% by mass or more and 85% by mass or less, even more preferably 65% ​​by mass or more and 80% by mass or less, and even more preferably 68% by mass or more and 75% by mass or less.

[0052] In the nanofiber sheet 1 used in the present invention, the content of the adhesive polymer is preferably 2% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, still more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoints of good skin compatibility, excellent transferability, and reducing wrinkling of the nanofiber sheet adhered to the skin and the inclusion of air bubbles, and from the same viewpoints, it is preferably 45% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, still more preferably 33% by mass or less, and even more preferably 31% by mass or less. The content of the adhesive polymer is preferably 2% by mass or more and 45% by mass or less, more preferably 10% by mass or more and 40% by mass or less, even more preferably 15% by mass or more and 35% by mass or less, still more preferably 20% by mass or more and 33% by mass or less, and even more preferably 25% by mass or more and 31% by mass or less.

[0053] From the viewpoint of further improving both the transferability and compatibility of the nanofiber sheet, it is preferable to specify the blending ratio of the water-insoluble polymer with relatively low moisture absorption in a high temperature and high humidity environment and the relatively high adhesive polymer as follows. In the nanofiber sheet used in the present invention, the proportion of adhesive polymer in the total polymer, including the water-insoluble polymer and adhesive polymer (hereinafter sometimes simply referred to as the proportion of adhesive polymer), from the viewpoints of good skin compatibility, excellent transferability, and reducing wrinkling of the nanofiber sheet adhered to the skin and the inclusion of air bubbles, is preferably 0.05 or more, more preferably 0.11 or more, even more preferably 0.15 or more, even more preferably 0.18 or more, even more preferably 0.21 or more, and from the same viewpoints, it is preferably 0.60 or less, more preferably 0.52 or less, even more preferably 0.46 or less, even more preferably 0.40 or less, even more preferably 0.38 or less, and even more preferably 0.34 or less. The ratio of the adhesive polymer to the total polymer, including the water-insoluble polymer and the adhesive polymer, is preferably 0.05 to 0.60, more preferably 0.11 to 0.52, even more preferably 0.15 to 0.46, still more preferably 0.18 to 0.40, still more preferably 0.21 to 0.38, and still more preferably 0.21 to 0.34. The ratio of the adhesive polymer is calculated by the following formula (2), where the mass (content) of the water-insoluble polymer in the nanofiber sheet is M1 and the mass (content) of the adhesive polymer is M2. Ratio of adhesive polymer = M2 / (M1+M2) ... (2)

[0054] In the nanofiber sheet used in the present invention, the water-insoluble polymer and the adhesive polymer are combined, and the nanofiber sheet is composed of a water-insoluble polymer with relatively low moisture absorption and a highly adhesive polymer in the above-mentioned blending ratio, thereby improving the moisture resistance of the nanofiber sheet, and even in a storage environment or a use environment of the nanofiber sheet, such as a high temperature and humidity environment, the occurrence of an event in which the nanofiber sheet dissolves due to moisture absorption and remains on the base layer is suppressed. This makes it possible to improve the transferability of the nanofiber sheet. In addition, even when the skin to which the nanofiber sheet is attached is exposed to a high temperature and humidity condition such as a bathroom or a dressing room for a long time, the nanofiber sheet is difficult to dissolve, and the nanofiber sheet can be made to have a stable film shape and maintain quality. In addition, the good compatibility with the skin makes it difficult for the nanofiber sheet to become twisted or have air bubbles mixed in, and the boundary between the skin to which the nanofiber sheet is attached and the skin to which the nanofiber sheet is not attached is difficult to distinguish, making it possible to achieve a natural appearance that does not feel the presence of the nanofiber sheet.

[0055] In addition to the one or more polymers, the nanofiber sheet used in the present invention may contain, for example, plasticizers for the polymers, oils, surfactants, fragrances, repellents, antioxidants, stabilizers, preservatives, various vitamins, etc. Examples of plasticizers that can be contained in the nanofiber sheet include alkylene glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, and 1,3-butylene glycol; polyalkylene glycols such as diethylene glycol, dipropylene glycol, polyethylene glycols and polypropylene glycols having a molecular weight of 1000 or less; and polyols such as glycerin, diglycerin, and triglycerin. Examples of oils include one or more selected from silicone oils such as methylpolysiloxane; ester oils such as dipenta-oliot fatty acid ester; and amino acid ester oils such as di(octyldodecyl / phytosteryl / behenyl) lauroyl glutamate. From the viewpoint of usability such as the compatibility of the nanofiber sheet, the amino acid ester oil is preferably contained in the nanofiber sheet at 1 mass% or more, more preferably 2 mass% or more, and even more preferably 3 mass% or more; and from the viewpoint of similar usability, the amino acid ester oil is preferably contained in the nanofiber sheet at 1 mass% or less, more preferably 9.8 mass% or less, and even more preferably 9.6 mass% or less.

[0056] The nanofiber sheet used in step (2) is a nanofiber sheet that has been formed in advance on a substrate, preferably by, for example, electrospinning. The substrate may be any substrate other than skin, and may be, for example, a film made of a synthetic resin, such as a polyolefin resin or a polyester resin, or a fiber sheet, such as a nonwoven fabric. In addition, from the viewpoint of facilitating peeling of the nanofiber sheet from the skin after it is transferred to the skin, it is preferable that at least the contact surface between the nanofiber sheet and the substrate is breathable. By allowing air to enter between the nanofiber sheet and the substrate, the nanofiber sheet can be easily peeled off. The nanofiber sheet used in step (2) does not mean, for example, a nanofiber sheet formed by a user using a handy electrostatic spray device, but preferably means a nanofiber sheet formed on a substrate and stored in a package until use. There are no restrictions on the material of the packaging material, and it can be, for example, a laminated film in which a barrier layer such as an aluminum sheet (aluminum foil) or a silica vapor deposition film is sandwiched between the layers and the front and back of the layer are covered with synthetic resin film layers made of, for example, polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyvinyl chloride, etc. Furthermore, there is no limitation on the shape of the package, and it can be, for example, a pillow bag, a gusset bag, a pouch, a box, a bottle, a jar, or the like. A single package may contain one nanofiber sheet, or two or more nanofiber sheets. Also, two or more nanofiber sheets may be connected and contained in a single package. In this case, for example, perforations may be provided in the nonwoven fabric, and the sheet-type cosmetic material to be used can be cut along the perforations and used. The nanofiber sheet in this embodiment is preferably contained in a package, and more preferably sealed in a package.

[0057] As the breathable substrate, a fiber sheet or a sponge is preferably used. Specifically, the fiber sheet is various nonwoven fabrics, woven fabrics, knitted fabrics, paper, mesh sheets, and laminates thereof. Examples of nonwoven fabrics include, but are not limited to, meltblown nonwoven fabrics, spunbond nonwoven fabrics, air-through nonwoven fabrics, spunlace nonwoven fabrics, and rayon nonwoven fabrics. The fibers or strands constituting these fiber sheets such as nonwoven fabrics and mesh sheets are preferably thicker than those in the category of nanofiber sheets. In addition, fibers made of fiber-forming synthetic resins and natural cellulose fibers such as cotton and pulp can be used as fibers. Specifically, the sponge is made of a porous material obtained by foaming synthetic resins or natural resins, such as foamed resins. Examples of synthetic resins or natural resins that can be used include, but are not limited to, urethane, polyethylene, melamine, natural rubber, chloroprene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber. Various materials can be used as the foamed resin as long as they can form a breathable form. From the viewpoint of easily attaching and peeling the nanofiber sheet to the skin after application in step (1), the substrate is more preferably a nonwoven fabric.

[0058] When the substrate layer is laminated to the nanofiber sheet in a peelable manner, it is preferable to apply a release treatment such as coating with a silicone resin or corona discharge treatment to the surface of the substrate facing the nanofiber sheet in order to improve the peelability. Also, when a synthetic resin film or the like is used as the substrate, it is preferable to coat the surface of the film with a release agent by dispersing a powder or granular release agent on the surface of the film. Examples of the release agent include silicone-based, fluorine-based, alkyd-based, olefin-based, and long-chain alkyl-based release agents.

[0059] The operation of step (2) involves attaching the nanofiber sheet formed on the substrate to the skin after application of step (1), together with the substrate, and then peeling off only the substrate. This simple operation allows a uniform UV protective coating to be formed on the skin.

[0060] Another aspect of the present invention is a kit for forming an ultraviolet ray protective coating on skin, comprising: a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer; and a composition containing an ultraviolet ray protective agent. The kit of the present invention may include "a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer" and "the ultraviolet protection agent-containing composition." The surface of the nanofiber sheet formed on the substrate facing the nanofiber sheet may have a release agent and a release sheet. The kit of the present invention may also include a procedure and a protocol for use.

[0061] In relation to the above-mentioned embodiments, the present invention further discloses the following methods and kits. <1> A step (1) of applying a composition containing an ultraviolet protection agent to the skin; A method for forming an ultraviolet ray protective coating on skin, comprising: step (1) applying a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer; and step (2) transferring the nanofiber sheet to the skin after application. <2> The ultraviolet protection agent is an ultraviolet protection agent selected from an organic ultraviolet absorber and an ultraviolet scattering agent, and is preferably an organic ultraviolet absorber selected from a benzoic acid-based ultraviolet absorber, an anthranilic acid-based ultraviolet absorber, a salicylic acid-based ultraviolet absorber, a cinnamic acid-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, and a triazine-based ultraviolet absorber. <1> The method described. <3> The content of the ultraviolet protection agent in the ultraviolet protection agent-containing composition is 0.1% by mass or more and 30% by mass or less, preferably 1% by mass or more and 25% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and further preferably 10% by mass or more and 18% by mass or less. <1> or <2> The method described. <4> The ultraviolet protection agent-containing composition further contains an oil that is liquid at 20° C., preferably an oil that is liquid at 20° C. selected from the group consisting of hydrocarbon oils, vegetable oils, animal oils, ester oils and silicone oils. <1> ~ <3> 2. The method according to claim 1 , <5> The ultraviolet protection agent-containing composition further contains a component selected from water and a polyol. <1> ~ <4> 2. The method according to claim 1 , <6> The substrate is a fiber sheet. <1> ~ <5> 2. The method according to claim 1 , <7> The substrate is a nonwoven fabric. <1> ~ <5> 2. The method according to claim 1 , <8> The nanofiber sheet contains a water-insoluble polymer and an adhesive polymer. <1> ~ <7> 2. The method according to claim 1 , <9> When the mass of the water-insoluble polymer in the nanofiber is (M1) and the mass of the adhesive polymer is (M2), the value of M2 / (M1+M2) is 0.05 or more and 0.60 or less. <1> ~ <8> 2. The method according to claim 1 , <10> The water-insoluble polymer has a moisture absorption of 1% or less when left standing in a high-temperature and high-humidity environment (40°C, 90% RH for 24 hours). <1> ~ <9> 2. The method according to claim 1 , <11> The adhesive polymer has a moisture absorption of 5% or more and 29% or less when left standing in a high temperature and high humidity environment (40°C, 90% RH for 24 hours). <8> ~ <10> 2. The method according to claim 1 , <12> The nanofiber has a thickness, expressed as a circle equivalent diameter, of 10 to 3000 nm, preferably 10 to 1000 nm, and a length of 100 times or more of the diameter. <1> ~ <11> 2. The method according to claim 1 , <13> The thickness of the nanofiber sheet is preferably 5.1 μm or more and 500 μm or less, more preferably 10 μm or more and 400 μm or less, and even more preferably 10 μm or more and 100 μm or less. <1> ~ <12> 2. The method according to claim 1 , <14> The water-insoluble polymer is one or more selected from the group consisting of polyvinyl butyral resin, polyurethane resin, and polylactic acid. <1> ~ <13> The method according to any one of the preceding claims. <15> The adhesive polymer is one or more selected from polyvinylpyrrolidone, a copolymer of polyvinylpyrrolidone, a polyalkylene glycol, and a copolymer containing a silicone structure. <8> ~ <14> The method according to any one of the preceding claims. <16> The nanofiber sheet further contains one or more oils selected from silicone oil, ester oil, and amino acid-based ester oil. <1> ~ <15> 2. The method according to claim 1 , <17> The content of amino acid ester oil in the nanofiber sheet is 10% or less. <16> The method described. <18> A kit for forming an ultraviolet ray protective coating on skin, comprising: a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer; and a composition containing an ultraviolet ray protective agent. <19> The substrate is a fiber sheet. <18> A kit for forming an ultraviolet ray protective coating according to the present invention. EXAMPLES

[0062] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0063] [Manufacturing of nanofiber sheets] A rayon nonwoven fabric (product name: Omikenshi 45, Omikenshi Co., Ltd.) was used as the substrate layer, and a nanofiber sheet was formed on the substrate by electrospinning using an electrostatic spray device and a nanofiber sheet forming composition (Tables 1 to 4), to produce the nanofiber sheets of each example. The production conditions for the nanofiber sheets are as follows. Applied voltage: 27 kV, distance between capillary collectors: 185 mm, discharge rate of composition for forming nanofiber sheet: 1 ml / h, production environment: 28°C, 36% RH. The thus obtained nanofiber sheet of each Example had a thickness of 30 μm, and the nanofibers had a thickness of 300 to 600 nm.

[0064] The content ratio (mass %) of the water-insoluble polymer and the adhesive polymer in the nanofiber sheet produced in each Example, and the proportion of the adhesive polymer calculated by the above formula (2) are shown in Tables 7 to 11. The mass ratio of the water-insoluble polymer and the adhesive polymer in the composition for forming a nanofiber sheet was the same as the mass ratio of the water-insoluble polymer and the adhesive polymer in a nanofiber sheet formed using the composition for forming a nanofiber sheet. The nanofiber sheet had a rectangular shape measuring 2.5 cm x 5 cm.

[0065] [Examples 1 to 18, Comparative Examples 1 to 2] A composition containing an ultraviolet protection agent (Tables 5 and 6) was applied at 1.3 g / cm on a substrate (HD-6 manufactured by Labsphere). 2 Then, a nanofiber sheet shown in Tables 7 to 10 was transferred to form an ultraviolet protective coating. Immediately after that, the following items were evaluated. For Comparative Example 1, the UV protection agent-containing composition alone was evaluated without transferring the nanofiber sheet. For Comparative Example 2, a UV protection coating was formed by electrostatically spraying the nanofiber sheet-forming composition A directly onto the skin after application of the UV protection agent-containing composition.

[0066] [Evaluation of moisture resistance of cast film] The moisture resistance of the cast films was evaluated as follows. 0.35 g of the polymer to be evaluated was dissolved in 4.65 g of ethanol (99% ethanol) to prepare 5 g of polymer solution. The polymer solution was prepared with a ratio of 7% polymer and 93% ethanol by mass %. The polymer solution was placed in a 5 cm square plastic shell and dried at room temperature for 72 hours to volatilize the ethanol and prepare a cast film. Next, the prepared cast film was left in an incubator at 40°C and 90% RH (high temperature and high humidity environment) for 24 hours. The weight change rate of the cast film before and after leaving it in a high temperature and high humidity environment was calculated. Based on the weight change rate, the hygroscopicity of the cast film was evaluated on a four-level scale from A to D as follows. A: 0%≦Weight change rate≦5% B: 5%< weight change rate ≦ 10% C: 10%< weight change rate ≦ 15% D: 15% < weight change rate

[0067] [Evaluation of usability before and after storage in high temperature and humidity] The nanofiber sheets produced in each Example were evaluated by five expert panelists for their usability before and after storage at high temperature and humidity. For evaluation of the nanofiber sheet before storage at high temperature and humidity, the nanofiber sheet immediately after production was used. To evaluate the nanofiber sheets after storage at high temperature and humidity, the nanofiber sheets immediately after production were packed in breathable packaging material and left to stand in an incubator at 40°C and 90% RH (high temperature and humidity environment) for 24 hours. To evaluate the usability of the nanofiber sheet on the skin after applying a composition containing an ultraviolet protection agent, four aspects were evaluated: transferability, skin compatibility, appearance, and film durability. The expert panelists used the skin on the inside of their own forearms as the test site for application and evaluated the transferability of the nanofiber sheet onto the skin, how well the nanofiber sheet blended with the skin after transfer, the appearance of the nanofiber sheet attached to the skin, and the appearance of the nanofiber sheet when it was rubbed against the skin with a finger 10 times, in terms of film durability. Five expert panelists rated each evaluation item on a four-point scale from 1 to 4 points in accordance with the item evaluation criteria described below, and based on the overall average score, rated the usability of the nanofiber sheet on a four-point scale from A to D in accordance with the usability evaluation criteria described below.

[0068] (Item evaluation criteria) 4 points...Good 3 points…average 2 points...bad 1 point: Very bad

[0069] (Usability evaluation criteria) A:3.5≦Overall rating≦4.0 B: 3.0≦Overall rating<3.5 C: 2.5≦Overall rating<3.0 D: Overall rating < 2.5

[0070] [Evaluation of UV protection ability] [SPF] To compare the UV protection performance of the obtained coating, an SPF test was conducted. The coating formed on the substrate was measured at five points, and the average value was taken as the SPF. The measurement was performed using an SPF analyzer (UV-2000S manufactured by Labsphere). A: SPF value 50 or less B: 30≦SPF value<40 C: 20≦ SPF value<30 D: SPF value < 20

[0071] [Homogeneity] The CV value, which is the coefficient of variation of the SPF values ​​measured five times, was used as an index of the homogeneity of the coating. CV(%)=(standard deviation / average value)×100 A: CV value < 15% B: 15%≦CV value<20% C: 20%≦CV value<25% D: 25% ≤ CV value

[0072] [Sustainability] The coating was rubbed with a finger 10 times, and the SPF was measured before and after. The ratio (%) of the SPF value after rubbing to the SPF value before rubbing was used as an index of the durability of the coating. SPF retention rate: [SPF value (after rubbing) / SPF value (after rubbing)] x 100 A: 80% or less SPF duration B: 65%≦SPF durability<80% C: 50%≦SPF retention rate<65% D: SPF persistence rate <50%

[0073] [Table 1]

[0074] [Table 2]

[0075] [Table 3]

[0076] [Table 4]

[0077] [Table 5]

[0078] [Table 6]

[0079] [Table 7]

[0080] [Table 8]

[0081] [Table 9]

[0082]

Table 10

Claims

1. Step (1) involves applying a composition containing a UV protection agent to the skin, A method for forming an ultraviolet protective film on skin, comprising the steps of (1) transferring a nanofiber sheet, in which a nanofiber structure is formed by a water-insoluble polymer, to skin after application (2).

2. The method for forming an ultraviolet protective coating according to claim 1, wherein the substrate is a fiber sheet.

3. The method for forming an ultraviolet protective film according to claim 1 or 2, wherein the water-insoluble polymer is a polymer whose moisture absorption is 1% or less when left standing for 24 hours under high temperature and high humidity conditions (at 40°C and 90% RH).

4. The method for forming an ultraviolet protective film according to claim 1 or 2, wherein the nanofiber sheet contains a water-insoluble polymer and an adhesive polymer.

5. A method for forming an ultraviolet protective coating according to claim 1 or 2, wherein when the mass of the water-insoluble polymer in the nanofiber is (M1) and the mass of the adhesive polymer is (M2), the value of M2 / (M1+M2) is 0.05 or more and 0.60 or less.

6. The method for forming an ultraviolet protective film according to claim 4, wherein the adhesive polymer is a polymer whose moisture absorption is more than 1% and less than or equal to 40% under high temperature and high humidity conditions (standing for 24 hours at 40°C and 90% RH).

7. The method for forming an ultraviolet protective coating according to claim 1 or 2, wherein the content of amino acid-based ester oil in the nanofiber sheet is 10% or less.

8. A kit for forming an ultraviolet-protective film on the skin, comprising a nanofiber sheet formed on a substrate, the nanofiber sheet having a nanofiber structure formed by a water-insoluble polymer, and a composition containing an ultraviolet-protective agent.

9. The UV-protective coating forming kit according to claim 8, wherein the substrate is a fiber sheet.