Evaluation method for ultraviolet protection effect of cosmetic

Abstract

To obtain an evaluation method for ultraviolet transmission ratio of cosmetic which solves the existing problem.SOLUTION: An evaluation method for ultraviolet protection effect of cosmetic includes a preparation step for preparing a measuring sample to evaluate the ultraviolet protection effect of a cosmetic. The preparation step includes forming a uniform cosmetic coating layer on a transparent base surface for the ultraviolet transmission measurement using an applicator formed with a material layer having oil-repellent properties.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the UV protection performance of cosmetics. [Background technology]

[0002] The technical background of the present invention will be described below. Currently, in Japan, the indicators used to measure the UV protection effect of cosmetics are SPF (Sun Protection Factor), which indicates the ability to protect against UVB rays with wavelengths of 290 to 320 nm, and UVA-PA (Protection Grade of UVA), which indicates the ability to protect against UVA rays with wavelengths of 320 to 400 nm. When these measurement results are displayed on cosmetics, the values ​​or grades measured based on the respective measurement method standards established by the Japan Cosmetic Industry Association (Non-Patent Documents 1 and 2) must be displayed. Although overseas countries are also required to display the results according to the measurement and display methods of each region (Non-Patent Document 3), the basic measurement methods are almost standardized. The standard measurement method involves using a human back, irradiating the back with high-power ultraviolet light, and measuring the UV protection effect based on the results of visual observation of the inflammatory and darkening reactions that occur on the skin. However, using humans is time-consuming and expensive, and it takes a long time to obtain the measurement results. In addition, due to ethical and medical issues associated with using humans, studies are underway in Japan and Europe to develop a method for measuring UV protection effectiveness using machines without using humans (Non-Patent Document 4). However, it has been reported that the currently used measurement methods have many problems (Non-Patent Document 5). The inventor's research has also found that SPF values ​​can vary by up to 20 times, even when testing using the same sample under the same standards.

[0003] This problem can be largely resolved by using the method described in Patent Document 1. However, when further investigations were carried out using this method, a new problem arose: when substrates with different contact angles with water were used, the measured values ​​of the sample changed significantly (Non-Patent Document 6). Therefore, there was a need to develop a measurement method that was as hassle-free as possible and allowed for highly accurate measurements, and the inventions of Patent Documents 2 to 7, primarily Patent Documents 2 and 3, which were invented by the present inventors, made it possible to perform highly accurate measurements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 047707 [Patent Document 2] Patent No. 6741261 [Patent Document 3] Patent No. 6842778 [Patent Document 4] Patent No. 5825654 [Patent Document 5] Patent Publication No. 2021-65873 [Patent Document 6] Japanese Patent Application Publication No. 2023-57509 [Patent Document 7] Japanese Patent Publication No. 2023-95723 [Non-patent literature]

[0005] [Non-Patent Document 1] Japan Cosmetic Industry Association, UV Protection Cosmetics and UV Protection Effect -SPF and PA Labeling- 2003 Revised Edition [Non-patent document 2] Japan Cosmetic Industry Association Japan Cosmetic Industry Association SPF Measurement Method Standards (2007 Revised Edition) [Non-patent document 3] ISO / TR26369 Cosmetics -- Sun protection test methods -- Review and evaluation of methods to assess the photoprotection of sun protectionproducts [Non-patent document 4] Colipa Guidelines, Method for in vitro Determination of UVAprotection, 2009 [Non-patent document 5] Ruppert, S.; Bimzcok, R.; Klebon, B.; Heinrich, U.; Tronnier, H.; Johncock, W.; Peters, S.; Pfluecker, F.; Rudolph, T.; Floesser-Mueller, H.; Jenni, K.; Kockott, D.; Lademann, J.; Herzog, B.; Bielfeldt, S.; Mendrok-Edinger, C.; Hanay, C.; Zastrow, L. “in vitro SunProtection Factor: Still a Challenge with No Final Answer” Skin Pharmacol.Phys. 2010, 23(4), 201-212. [Non-patent document 6] K. Asakura, A. Kuroda, IFSCC Magazine 21(2), 53-57 (2018). Summary of the Invention [Problem to be solved by the invention]

[0006] Cosmetics have different physical properties depending on their composition, such as hydrophilicity, lipophilicity, and properties intermediate therebetween. When cosmetics are applied to only one type of substrate with a fixed contact angle with water, some cosmetics can be applied evenly, but other cosmetics cannot be applied evenly, and the cosmetics may undergo phase separation or be repelled from part of the substrate surface, resulting in an uneven coating film with part of the substrate surface exposed. For this reason, even if measurement accuracy is improved, the characteristics can only be grasped by preparing substrates with many different contact angles in advance and plotting the measured values ​​for each on a graph, and even measuring a single product can require a lot of effort, as it is necessary to measure substrates with multiple types of contact angles. This laborious effort is much greater than that of the in vivo method, meaning that it cannot be used as a practical alternative. Furthermore, when we measured over 200 commercially available cosmetics from around the world using conventional methods, we found that some products behaved differently than we expected. Therefore, we investigated the cause of this. We found that, because the applicator is made of metal, phase separation of the cosmetics occurs in the gap and front of the applicator, especially for cosmetics with a strong affinity for lipophilic metals. As a result, most of the cosmetics adhere to the applicator, leaving almost no cosmetics remaining on the substrate surface. Furthermore, even for formulations that did not exhibit this phenomenon, we used an infrared imaging microscope to examine the changes in the amount of UV absorber in the coating film, whose thickness was confirmed to be constant using a rotary film thickness meter. When using a stainless steel four-sided applicator, we found that there were periods when the concentration of UV absorber increased periodically, i.e., the concentration of UV absorber varied depending on the location of the coating. This indicated that measuring the film thickness alone was inaccurate. Furthermore, when corona discharge treatment is performed to create a superhydrophilic substrate, the corona discharge treatment device generates strong electromagnetic noise, making it unsuitable for use in office buildings, etc. Furthermore, when a cosmetic is applied to the substrate surface, the resulting coating film may have a large, uneven striped pattern. In this case, if a rotary wet film thickness meter is used to measure the coating film thickness, the measured value will differ significantly from the actual film thickness. Furthermore, the values ​​obtained using the calculation formula specified in the ISO method shown in Non-Patent Document 4 differ from the data obtained from humans and subjects. An object of the present invention is to provide a method for evaluating the ultraviolet transmittance ratio of a cosmetic product that solves the above problems. [Means for solving the problem]

[0007] By adopting the following configuration, instead of an applicator with a metal (stainless steel) surface, an applicator was used in which a material layer with oil-resistant properties (obtained by wrapping a resin film around the surface) was formed on the surface of a cylindrical applicator, thereby preventing excessive adhesion of oily components of cosmetics in particular to the applicator. Instead of using corona-discharge-treated quartz plates, we employed multiple types of substrates for evaluating UV transmittance ratios with different contact angles, such as transparent substrates for measuring UV transmittance, which were made superhydrophilic by coating the surfaces of corona-discharged quartz plates or other materials with various materials, such as inulin. A single cosmetic was applied to each of these substrates, and a uniform cosmetic layer was formed on the surface using an applicator made of a material with an oil-resistant surface. Experiments demonstrated that a uniform thin layer of cosmetic could be formed on at least one of the multiple UV transmittance ratio evaluation substrates, regardless of the cosmetic's properties (e.g., hydrophilic, lipophilic, or intermediate properties, and liquid, solid, cream, or stick form). This approach eliminated the need for a corona discharge device for surface treatment of substrates at the test site. As a result, instead of using a rotary wet film thickness meter, more accurate measurements can be performed by comparing the absorbance value at a specific wavelength of the applied cosmetic layer measured by a spectrophotometer with the absorbance value at the same specific wavelength of a 100 μm-thick assembly cell, and calculating the thickness of the cosmetic layer. This has resulted in the development of a simpler and more accurate method for evaluating the UV transmittance ratio of cosmetics. Furthermore, the formula for calculating the SPF value and UVA-PF value from absorbance is not specified by the ISO method, thereby obtaining measurement results that are more closely correlated with human test data. Note that the UV transmittance ratio evaluation substrate will sometimes be referred to simply as the "substrate" below.

[0008] 1. A method for evaluating the UV protection performance of cosmetics, comprising a step of preparing a measurement sample for evaluating the UV protection performance of cosmetics, the preparation step comprising a method of forming a uniform cosmetic application layer on the surface of a transparent substrate for measuring UV transmittance using an applicator formed of a material layer having oil-resistant properties. 2. A method for evaluating the UV protection performance of cosmetics according to 1, wherein the material layer having an oil-resistant surface is a layer made of one or more materials selected from polyethylene naphthalate (PEN) film, hydrophilic-treated polyester film, hydrophilic-treated polyethylene terephthalate film, and fluororesin film, all of which have oil-resistant properties. 3. A method for evaluating the UV protection performance of a cosmetic composition according to 1 or 2, comprising the following steps A to D: A. A process for preparing multiple measurement samples for evaluating the UV protection performance of cosmetics, in which a single cosmetic is applied to each of multiple types of UV transmittance ratio evaluation substrates with different contact angles, forming a uniform cosmetic layer using an applicator whose surface is formed from a material layer with anti-adhesion properties. B. A process of measuring the absorbance of a standard thickness of a cosmetic product using an assembled cell and calculating the SPF value and UVA-PF value using the following formula: SPF value obtained by integrating the wavelengths from 290 to 320 nm in 1 nm increments using the formula CF × ΣEE(λ) × I(λ) × Abs(λ) The UVA-PF value is calculated by integrating the wavelengths from 320 to 400 nm in 1 nm increments using the formula CF × ΣEE(λ) × I(λ) × Abs(λ). where CF is the correction factor (=10), EE is the erythemal effect spectrum, I is the solar intensity spectrum, and Abs is the absorbance of the sunscreen product. C. A process of selecting the measurement sample with the highest SPF value based on the SPF values ​​obtained for multiple measurement samples, and determining the SPF value and UVA-PF value of that measurement sample as the in vitro SPF value and in vitro UVA-PF value of that one type of cosmetic. D. A step of determining the in vivo SPF equivalent value of the one cosmetic product from the relational expression between the in vivo SPF value and the in vitro SPF value, and further determining the in vivo UVA-PF equivalent value of the one cosmetic product from the relational expression between the in vivo UVA-PF value and the in vitro UVA-PF value. 4. The method for evaluating the UV protection performance of cosmetics according to 3, wherein the multiple types of transparent substrates for measuring UV transmittance with different contact angles are three types: a transparent substrate for measuring UV transmittance having a layer coated on its surface with polyisocyanate, a transparent substrate for measuring UV transmittance having a layer coated with inulin, and a transparent substrate for measuring UV transmittance having a layer coated with hydroxyalkyl cellulose. 5. A method for evaluating UV protection performance according to 3 or 4, characterized in that the relationship equation between the in vivo SPF value and the in vitro SPF value, and the relationship equation between the in vivo UVA-PF value and the in vitro UVA-PF value, are determined by statistically processing the relationship between the SPF value, UVA-PF value of the cosmetic obtained by the in vivo method or the in vivo UVA-PF value corresponding to the PA classification, and the SPF value and UVA-PF value determined by steps A to D. 6. The method for evaluating UV protection performance according to any one of 1 to 5, wherein the cosmetic is a powder cosmetic or a stick-type cosmetic, or a paste-like product obtained by mixing a solid cosmetic with a non-volatile oil. [Effects of the Invention]

[0009] By adopting the method for evaluating the ultraviolet transmittance ratio of a cosmetic product of the present invention, it is possible to evaluate all cosmetic products in various forms, including solution-type cosmetics, emulsion-type cosmetics, powder-type cosmetics, paste-type cosmetics, stick-type cosmetics, etc., and it is possible to obtain more accurate, precise, and stable measurement values ​​for all cosmetic products. In particular, highly accurate measurements have not been carried out for powder-type cosmetics and stick-type cosmetics up to now, and this method has made it possible for the first time to carry out measurements for all of the above-mentioned various cosmetic products in various forms. [Brief explanation of the drawings]

[0010] [Figure 1] Evaluation method flowchart [Figure 2] An example of the change in absorbance with heating time [Figure 3] External view of the assembly cell installed on the jig for installing the spectrophotometer [Figure 4] Perspective view of a metal applicator [Figure 5] Bottom view of the metal applicator [Figure 6] Cross section of a metal applicator [Figure 7] Cross-sectional view of the applicator used in coating process 2 [Figure 8] Perspective view of a cylindrical applicator [Figure 9] Cross section of a cylindrical applicator [Figure 10] Observation example of a coating applied using a stainless steel cylindrical applicator using an infrared imaging microscope [Figure 11] Observation example using an infrared imaging microscope of a coating film applied using a cylindrical applicator with a hydrophilic polyethylene terephthalate film fixed to the surface that comes into contact with the cosmetic during application. [Figure 12] Observation example using an infrared imaging microscope of a coating film applied using a cylindrical applicator with a non-hydrophilized polyethylene terephthalate film fixed to the surface that comes into contact with the cosmetic during application. [Figure 13] Observation example using an infrared imaging microscope of a coating film applied using a cylindrical applicator with polyimide tape fixed to the surface that comes into contact with the cosmetic during application. [Figure 14] Observation example using an infrared imaging microscope of a coating film applied using a cylindrical applicator with polyvinyl chloride tape fixed to the surface that comes into contact with the cosmetic during application. [Figure 15] Observation example using an infrared imaging microscope of a coating film applied using a cylindrical applicator with silicone rubber fixed to the surface that comes into contact with the cosmetic during application. [Figure 16] Observation example using an infrared imaging microscope of a coating film applied using a cylindrical applicator with a polyethylene naphthalate film fixed to the surface that comes into contact with the cosmetic during application. [Figure 17-1] Table in APPENDIX I of Non-Patent Document 4 [Figure 17-2] Table in APPENDIX I of Non-Patent Document 4 [Figure 17-3] Table in APPENDIX I of Non-Patent Document 4 DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. The method for evaluating the UV transmittance ratio of the present invention, which includes a step of preparing a measurement sample for evaluating the UV protection performance of a cosmetic, is a measurement method for obtaining a highly accurate and stable UV protection index for various cosmetic products, including emulsions including hydrophilic and lipophilic types, lotions, emulsified foundations, powder cosmetics, oil-based cosmetics, and sprays. As shown in Figure 1, in the present invention, multiple types of substrates are prepared as transparent substrate surfaces for measuring ultraviolet transmittance, such as three types: an inulin-treated substrate (hydrophilic substrate), a hydroxyalkyl cellulose-treated substrate (neutral substrate), and a polyisocyanate-treated (hydrophobic) substrate (lipophilic substrate). The cosmetic to be evaluated is applied to these substrates, for example, by applying coating steps 1, 2, and 3 in that order. The spectra of ultraviolet light transmitted through these substrates are measured. This is corrected to the spectrum when the cosmetic is, for example, 20 µm thick. The absorbance is calculated based on the absorbance when the cosmetic is 100 µm thick, as determined using a separate assembly cell. Next, from the three types of substrates, the substrate with the highest SPF value is selected. Based on the SPF and UVA values ​​for the substrate with the highest SPF value, the corresponding in vivo SPF and in vivo UVA PF values ​​are calculated using a predetermined formula.

[0012] <Cosmetics> The cosmetics of the present invention encompass a wide range of cosmetics, including makeup products and skincare products. Specifically, these include makeup cosmetics such as hydrophilic (O / W) emulsion sunscreens, lipophilic (W / O) emulsion sunscreens, multi-layer (O / W / O, W / O / W) emulsion sunscreens, and emulsion foundations, as well as makeup bases, sunscreen creams, multi-layer separation sunscreens, non-chemical sunscreens, day essences, daycare lotions, hand creams, solid foundations, powder cosmetics such as face powders, blushers, and eye shadows, lipsticks, oil-based cosmetics such as stick-type sunscreens, spray-type sunscreens, and roll-on sunscreens. The formulations may include liquids, emulsions, creams, lotions, essences, multi-layer separations, oil-based products, powders, and sheets. However, cosmetics with a UV transmittance of clearly 0% or 100% are not included. The cosmetic material is then applied to the skin, preferably at least one of the face, body, hands and feet, to obtain ultraviolet protection effects. This UV protection effect is generally expressed as an SPF value corresponding to UV-B rays with a wavelength of 290 to 320 nm, a UVA-PF value corresponding to UV-A rays with a wavelength of 320 to 400 nm, or an in vivo UVA-PF value or PPD value corresponding to the PA classification, but is not particularly limited as long as it is an index showing the protection effect for these wavelengths.

[0013] The ultraviolet absorber added to exhibit ultraviolet absorption properties is not particularly limited as long as it is one that can be added to cosmetics. Among such ultraviolet absorbers, oil-soluble ones include cinnamic acid-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzoic acid-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, and dibenzoylmethane-based ultraviolet absorbers. These may be used alone or in combination of two or more. Water-soluble ones include benzophenone-based ultraviolet absorbers, phenylbenzimidazole sulfonic acid and / or 2-hydroxy-4-methoxybenzophenone sulfonic acid. Those that are solid at room temperature include methylenebisbenzotriazolyltetramethylbutylphenol and trisbiphenyltriazine.

[0014] Examples of pigments that may be contained in the cosmetic preparation and that scatter or absorb ultraviolet light include fine particle titanium oxide, fine particle zinc oxide, fine particle cerium oxide, titanium oxide, zinc oxide, titania hydroxide sol, aluminum powder, and gold leaf powder. Furthermore, the cosmetic contains various ingredients that can be incorporated into cosmetics as ingredients other than these ultraviolet absorbers and / or pigments.

[0015] <Surface of transparent substrate for ultraviolet transmittance measurement> In the present invention, multiple types of substrates for evaluating ultraviolet transmittance ratios with different contact angles are used as the surface of the transparent substrate for measuring ultraviolet transmittance. In particular, two or more types of substrates are used from three types of substrates (lipophilic substrate, neutral substrate, and hydrophilic substrate). For example, multiple measurement samples are obtained using these three types of substrates. The three types of substrates have different contact angles with pure water. The contact angle of the substrate for evaluating ultraviolet transmittance ratios in the present invention is the contact angle of the substrate surface with pure water at 25°C. Hereinafter, the surface of the transparent substrate for measuring ultraviolet transmittance may be referred to as the "substrate for evaluating ultraviolet transmittance ratios." The substrates for evaluating the ultraviolet transmittance ratio are made by processing ultra-smoothed quartz plates or the like, and each plate is pre-treated for hydrophilicity or lipophilicity as necessary on its surface. Then, a lipophilic layer, a hydrophilic layer, and a contact angle adjusting layer with intermediate properties that exhibit a contact angle intermediate between these properties are provided. Among these, the above three types of substrates are preferred, as they transmit ultraviolet light in the 290 to 400 nm range. They must also have excellent stability over time.

[0016] The hydrophilization pretreatment involves treating the plate with physical means such as plasma treatment, arc discharge treatment, or corona discharge treatment to produce a hydrophilic substrate with a contact angle to pure water of 0 to 20°, preferably 0 to 10°, and more preferably 0 to 5°. The detailed conditions for these treatments, such as the applied voltage and treatment time, can be determined as desired depending on the desired contact angle. Furthermore, the atmosphere can be corona discharge treatment in air or plasma discharge treatment in a vacuum or oxygen or argon atmosphere. Of these, corona discharge treatment of quartz substrates is preferred. The lipophilic pretreatment can be achieved by coating the plate surface with a compound that exerts lipophilicity, or by subjecting the plate surface to plasma treatment, arc discharge treatment, corona discharge treatment, or the like in an atmosphere of a reactive compound that has lipophilicity. It should be noted that plates made of a material that is easily deformed by external forces, such as polymethyl methacrylate, are not preferred because they are prone to deformation during application of the cosmetic or cleaning, making it impossible to stably prepare or use a substrate for evaluating the ultraviolet transmittance ratio. Therefore, plates such as quartz plates that have high mechanical strength and transmit ultraviolet light in the 290 to 400 nm range uniformly across the entire wavelength range are preferred.

[0017] To obtain the above three types of substrates based on the plate, three different types of contact angle adjusting layers are formed on each of the three plates to obtain transparent substrates for measuring ultraviolet transmittance. In the present invention, in order to accurately evaluate the ultraviolet transmittance, each of the three types of contact angle adjusting layers formed on the plate surface must be smooth. The degree of smoothness is determined by the following testing method, and it is preferable that the maximum height of the unevenness is 1 μm or less.

[0018] (Method for inspecting unevenness) A thin layer of test solution (27% by weight isononyl isononanoate, 6% by weight ethylhexyl methoxycinnamate, 15% by weight titanium dioxide dispersion, 50% by weight petrolatum, and 2% by weight sorbitan isostearate) was applied to a quartz plate. A 10-cm wide stainless steel applicator with a 1 μm gap was then placed on the layer of test solution and moved slightly parallel to the plate surface to blend the applicator surface into the layer of test solution. After precisely smoothing the coating at a speed of 5 mm / s, the coating film was examined through a light source. If the coating film showed no shading, the plate surface was considered to be smooth and pass the test. This indicated that the plate surface also showed no shading when used on the following lipophilic, neutral, and hydrophilic substrates.

[0019] (Lipophilic substrate) The lipophilic substrate is prepared by smoothing the surface of the plate, optionally pretreating it to make it lipophilic, and then forming a lipophilic treatment layer on it to achieve a contact angle of 75 to 85° with pure water at 25°C. Typical urethane resins and urethane acrylates used in lipophilic treatment layers exhibit even higher contact angles, so they must be blended with other components to reduce the contact angle. Furthermore, acrylic resins of a grade suitable for coating are often unsuitable because they absorb ultraviolet light in the 290 to 400 nm wavelength range. Similarly, UV-curable resins are often unsuitable because the cured resins often have some absorption in the 290 to 400 nm wavelength range. Therefore, it is preferable to use acrylic polyisocyanates, polyurethanes, polyurethane acrylates, and copolymers of thiol compounds, isocyanate compounds, and acrylate compounds, which can be moisture-cured, as resins that can be applied smoothly and whose contact angle with pure water can be adjusted by adjusting the components and adding other components. These resins contain hydrophilic polyols, acrylates, and hydroxyl-containing acrylates in part of their molecular structure. By adjusting the blending ratio of these polyols, acrylates, and hydroxyl-containing acrylates, the contact angle with pure water can be adjusted to 75 to 85°.

[0020] (Intermediate substrate) The intermediate substrate is obtained by smoothing the surface of the plate, optionally carrying out a hydrophilic pretreatment or a lipophilic pretreatment, and then forming a layer having intermediate properties between hydrophilic and lipophilic. The surface of the intermediate substrate is preferably one having a contact angle of 50° to 60° with pure water at 25°C. For intermediate substrates in which the contact angle changes immediately after the formation of the layer having intermediate properties between hydrophilic and lipophilic, it is necessary to apply a cosmetic immediately after the formation of the layer having intermediate properties between hydrophilic and lipophilic.

[0021] The layer having intermediate properties between hydrophilicity and lipophilicity required to obtain such an intermediate substrate is preferably hydroxyalkyl cellulose (contact angle immediately after application: 51° to 52°). Alternatively, one or more of the following compounds may be selected and applied to the surface of the plate. Compounds having a sugar skeleton, such as mannose, galactose, xylose, glucose, maltose, lactose, sucrose, trehalose, fructose, cellulose, cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose, trisaccharides such as maltotriose and raffinose, tetrasaccharides such as inulin, oligosaccharides, glucan, agar, α-cyclodextrin, maltodextrin, corn starch, arrowroot starch, tapioca starch, potato starch, wheat starch, hydroxyethyl starch, hydroxypropyl starch, tamarind gum, xanthan gum, native gellan gum, and gellan gum, which are solubilized as necessary. Furthermore, sugar alcohols such as erythritol and xylitol, sugar-derived compounds, and other non-sugar compounds may or may not be added within the range that does not impair the effects of the present invention. Furthermore, in order to form a layer, it is preferable that the material is solid at room temperature and pressure, is not deliquescent, and is not insoluble in water at room temperature. "Not insoluble" means that the material has a solubility of 1 g / 100 mL or more in water at room temperature. A solubility of 5 g / 100 mL or more is even more preferable.

[0022] (Hydrophilic substrate) The hydrophilic substrate is obtained by forming a layer on the plate using a compound selected from the various compounds and combinations of various compounds used to obtain the intermediate substrate. Among these, tetrasaccharides such as inulin and hydroxyalkyl cellulose can be used to form a hydrophilic layer. When inulin is used, the contact angle with pure water at 25°C immediately after application is 23° to 26°, and the contact angle 5 minutes after application is 0° to 2.5°. It also has excellent stability over time.

[0023] The method for evaluating the UV protection performance of cosmetics of the present invention involves preparing a measurement sample by thinly coating the cosmetic onto three types of substrates (lipophilic substrate, neutral substrate, and hydrophilic substrate) that are used to evaluate the UV transmittance ratio. The measurement method is based on measuring the results using a spectrophotometer. An overview of the measurement method is shown in Figure 1, and the method will be explained using an emulsion sunscreen. [A. A process for preparing a plurality of measurement samples for evaluating the UV protection performance of cosmetics, which involves using one type of cosmetic to form a uniform cosmetic layer on each of the surfaces of a plurality of types of UV transmittance ratio evaluation substrates with different contact angles, using an applicator whose surface is formed of a material layer having adhesion prevention properties] <Coating cosmetics onto a substrate for evaluating UV transmittance ratio> The following optional coating step 1 and / or coating step 2 are carried out, and then the following coating step 3 is carried out as a preparation step, thereby preparing a measurement sample.

[0024] (Coating process 1) A cosmetic is applied to the surface of the substrate for evaluating ultraviolet transmittance ratio using a metal applicator with a gap of 500 μm to 1000 μm. For example, the substrate for evaluating ultraviolet transmittance ratio is placed on a support substrate made of extra super duralumin or the like with a thickness of 4 to 10 mm, and the coating is performed at a relative movement speed of 1 to 10 mm / sec, e.g., 5 mm / sec, relative to the metal applicator. Alternatively, the cosmetic may be spread on the substrate for evaluating ultraviolet transmittance ratio in advance using a spatula or the like, and then smoothed over with the metal applicator as needed.

[0025] Examples of the metallic applicator that can be used include those shown in FIGS. The metallic applicator is moved by a coating spreading device 1 shown in FIG. 4, for example. The coating spreading device 1 is a device having a coating spreading member 2 and support parts 3 for supporting both ends of the coating spreading member 2 . The spreading member 2 is supported by a structure (not shown) relative to the support part 3, for example, pins on both ends of the spreading member are fitted into grooves extending in the vertical direction on the support part 3, so that the spreading member can move freely up and down, and the weight of the spreading member allows it to resist the resistance exerted by the cosmetic material to be spread, thereby evenly applying the cosmetic material to the substrate. For the purpose of explanation, other components are not shown in the coating spreading device 1 shown in Figure 4, but in order to make it an integrated coating spreading device, it is possible to provide, for example, a component angle that connects the two support parts 3. Also, Figure 5 is a view of the coating spreading device 1 from below (a view of the coating spreading member 2 above from the base B side in Figure 6), and the coating spreading member tip 6 is located at the tip of the coating spreading member 2.

[0026] The material of the coating spreading member 2 and the support part 3 provided in the coating spreading device 1 is preferably metal, and in particular, a material with good dimensional accuracy and that is easy to process, such as stainless steel or duralumin, is preferred. The cross-sectional shape of the coating spreading member used in the present invention is preferably polygonal. Figure 6 is a cross-sectional view of the metal applicator during coating. Figure 6 also shows a base B for securing the substrate 4. Furthermore, as shown in Figure 5, the angle between the surface of the spreading member, which faces the direction of travel of the spreading device indicated by the arrow, and the surface of the substrate 4 to be coated must be 30° or greater. If the angle is less than 30°, the film thickness will not be consistent due to the resistance force exerted by the cosmetic 5 on the spreading member, and measurement accuracy may be reduced depending on the cosmetic. Similarly, if the spreading member has a shape such that the angle between the part of the spreading member closest to the substrate and the surface of the substrate to be coated approaches 0°, such as a cylindrical or elliptical cylindrical shape, the film thickness will not be consistent due to the resistance force exerted by the spreading member. Furthermore, in the coating step 1, the height of the gap formed between the tip 6 of the coating spreading member and the substrate 4 is preferably in the range of 500 μm to 1000 μm.

[0027] The mass of the coating spreading member, when used alone, is preferably 100 g or more, and more preferably 250 g or more. A small mass is susceptible to the effects of drag, making it difficult to form a smooth film. Furthermore, a mass that is too large can cause distortion in the substrate and the supporting plate, making the substrate less flat and resulting in variations in coating thickness depending on the coating area. The amount of mass that can be applied depends on the strength of the substrate and supporting plate, so it is difficult to generalize. However, when using 5 mm thick ultra-super duralumin, it has been observed that when a load is applied from above the coating spreading member and the combined load exceeds 2 kg, significant distortion of the substrate becomes apparent.

[0028] (Coating process 2) As shown in FIG. 7, the applicator used in coating step 2 has a cylindrical support P with a diameter of 30 to 40 mm attached to the tip of a rotating shaft. The cylindrical support has an axis passing through the center of each circular end face, which is connected to the rotating shaft. A resin sponge-like coating tool S, which has a rectangular parallelepiped shape with a width of 8 to 12 mm, a length of 30 to 35 mm, and a height of 8 to 12 mm, for example, is fixed to this support. The surface of the resin sponge-like coating tool S is flat, and the flat surface is used so that it is parallel to the surface of the ultraviolet transmittance ratio evaluation substrate 4. While rotating (e.g., at 200 to 250 rpm in the R direction), the resin sponge-like coating tool is rotated for a predetermined time so that it comes into contact with the layer of cosmetic applied to the surface of the ultraviolet transmittance ratio evaluation substrate 4 in coating step 1 (which exists between the resin sponge-like coating tool S and the surface of the ultraviolet transmittance ratio evaluation substrate 4, although not shown in FIG. 7), and is leveled for a predetermined time to form a thinner coating layer of the cosmetic formed in coating step 1. In this case, it is preferable that the surface of the resin sponge-like coating tool has a larger area than the ultraviolet transmittance ratio evaluation substrate, or that the length of the resin sponge-like coating tool S is longer than the width or diameter of the ultraviolet transmittance ratio evaluation substrate, and that the ends of the sponge-like coating tool do not come into contact with the coating layer of the cosmetic (in Figure 7, both ends of the resin sponge-like coating tool S extend beyond the ends of the ultraviolet transmittance ratio evaluation substrate 4). In addition, it is preferable that the sponge-like coating tool is made of urethane sponge.

[0029] (Coating process 3 (preparation process)) In the preparation step, a layer (a material layer on the applicator surface that selectively prevents the adhesion of oils and grease) is formed on the surface of the cosmetic coating layer obtained in coating step 2, for example, on the surface of a cylindrical applicator. The layer is made of a material with an oil-resistant surface (a material that essentially has the property of maintaining a dispersed state of the oils and other substances that disperse with the oils), and has the properties necessary to maintain a dispersed state of the oils contained in the cosmetic or the oils used to prepare the cosmetic into a measurement sample. Hereinafter, this layer will be referred to as an oil adsorption-suppressing layer or film. Then, this film is fixed to an applicator with double-sided tape. A modified applicator with a gap of 20 to 30 μm is used to apply the film to the surface of the substrate for evaluating the ultraviolet transmittance ratio at a speed of approximately 5 mm / s to prepare a measurement sample. Here, the oil adsorption-suppressing layer or film has an oil-resistant surface. Coating step 3 results in a measurement sample with a uniform cosmetic coating layer. Note that, since coating step 3 is a step for forming a thin cosmetic layer, it is necessary to limit the material of the applicator surface as described above. Coating steps 1 and 2 are for forming thicker cosmetic layers. Therefore, the applicator surface material used in coating steps 1 and 2 is not limited to a material that has the water repellency described above or the ability to maintain a dispersed state with other substances that are substantially dispersible with these oils, as in coating step 3.

[0030] The oil-resistant surface material used in coating process 3 must have the above properties, maintain a consistent film thickness when formed into a material layer, and not tear or wrinkle during coating. After examining the materials listed in Table 1, we found that hydrophilic-treated films, such as hydrophilic-treated polyester film and hydrophilic-treated polyethylene terephthalate film, as well as films and layers made of fluororesins such as polyvinylidene fluoride and polyethylene naphthalate (PEN) are preferred. In addition to polyvinylidene fluoride, other preferred fluororesins include tetrafluoroethylene, fluorinated ethylene propylene polymer, perfluoroalkoxy polymer, ethylene tetrafluoroethylene copolymer, ethylene chlorotrifluoroethylene copolymer, polychlorotrifluoroethylene, and polyvinyl fluoride. While any of these materials could be used, polyethylene naphthalate (PEN) film, known for its particularly excellent durability, was the most suitable. Layers made of fluororesins also performed well. Furthermore, although stainless steel has a contact angle with water of 90°, stainless steel may destroy the emulsion in emulsion-based cosmetics, resulting in the inability to form a uniform coating. The contact angles with water shown in Table 1 are contact angles with pure water at 25°C.

[0031] Next, a resin film (such as PEN) with a thickness of 25 μm and a surface roughness of 1.0 μm or less (as a material with an oil-resistant surface) was attached to a 100 μm gap stainless steel cylindrical applicator using a Nichiban Nicetack (weak adhesive, 60 μm thick) to avoid wrinkles, and the surface was then smoothed using a plastic scraper. This resin film-coated applicator (such as PEN) weighed only 266 g, and with highly viscous cosmetics, the applicator tended to lift during application, resulting in inconsistent film thickness. Therefore, a 248 g stainless steel block was placed on top of the applicator, and a total of 508 g was applied. In particular, because the surface roughness was 1.0 μm or less, a smooth cosmetic layer was formed. Furthermore, the smoother the surface of this resin film, the smoother the surface of the formed cosmetic layer, improving subsequent measurement accuracy. This characteristic remains unchanged regardless of the cosmetic's state (liquid or solid). Furthermore, all of the materials indicated above as materials whose surfaces have oil-resistant properties showed results similar to those of the PEN described above in the following examples. No special processing is required for the metal applicator with a gap of 500 μm to 1000 μm used in the above coating process 1. The problem of the applicator lifting up during coating becomes apparent when the applicator gap is narrow, so this is likely to occur in coating processes 1 and 2, but no special measures are required in coating process 1, where the gap is large.

[0032] An example of the cylindrical applicator is shown in FIG. The cylindrical applicator 7 is moved by a coating spreading device 9 shown in FIG. 8, for example. The coating spreading device 9 is a device having a cylindrical applicator 7 and support parts 8 for supporting both ends of the cylindrical applicator 7. The support parts 8 are used to fix the cylindrical applicator 7 to a frame or the like (not shown), or to support the cylindrical applicator 7 so that it can move as needed for coating and spreading. The cylindrical applicator 7 is supported by a structure (not shown) relative to the support part 8, for example, by fitting pins on both ends of the cylindrical applicator 7 into vertically extending grooves on the support part 8, or by molding the entire cylindrical applicator 7 as a single unit, thereby allowing free vertical movement. The weight of the cylindrical applicator 7 resists the resistance of the cosmetic material to be spread, thereby evenly applying the cosmetic material to the substrate. Alternatively, the cylindrical applicator 7 may be fixed to the support part 8. The cylindrical applicator 7 may be obtained by cutting a single metal block without any joints, or by assembling any desired components. For the purpose of explanation, other components are not shown in the coating spreading device 9 shown in Figure 8, but it is also possible to provide, for example, a component angle to connect the two support parts 8 to form an integrated coating spreading device 9. The cylindrical applicator 7 shown in FIG. 8 has a shape in which the coating spreading member 2 of the metal applicator is replaced with the cylindrical applicator 7. Furthermore, the cylindrical applicator 7 may or may not have a strictly circular cross-section perpendicular to the longitudinal direction of the cylinder. The cylindrical applicator 7 may be circular, or may have a circular shape with four chords and flattened sections as shown in FIG. 9, or a sector shape. Furthermore, the cross-section may be elliptical, or may be a shape of two overlapping circles or ellipses with a partially flat section, instead of the circular shape shown in FIG. 9. The portion of the cross-section that comes into contact with the cosmetic product may be a gentle curve or a horizontal plane. The cylindrical shape of the portion that comes into contact with the cosmetic product is not particularly limited, but the shape of the portion that comes into contact with the cosmetic product during application may be a curved surface that reflects a cylindrical shape with a cross-sectional diameter of 10 to 30 mm, or a curved surface that reflects an elliptical cross-section that is not circular but approximates such a curved surface. In the case of a horizontal surface, the width of the minor axis (in Figure 9, the length L, which is parallel to the arrow indicating the direction in which the cylindrical applicator moves relative to the substrate, for the above-mentioned gently sloping curve or horizontal plane facing substrate B) is preferably 1.0 to 5.0 mm, and more preferably 1.0 to 3.0 mm.

[0033] Figure 9 shows the cylindrical applicator 7 being moved in the direction of the arrow when applying a cosmetic. It is moved relative to the surface of the cosmetic coating layer, similar to the cylindrical applicator 7 described above. The portion of the cylindrical applicator that corresponds to the tip 6 of the spreading member is the approximately horizontal portion of the lower end of the cylindrical applicator 7 in Figure 9. This lower end portion moves the cylindrical applicator in the direction of the arrow, thereby similarly moving excess cosmetic 5. In this case, the gap formed between the cylindrical applicator 7 and the surface of the substrate 4 is preferably in the range of 500 μm to 1000 μm in coating step 1.

[0034] Although not shown in Fig. 8, the above-mentioned film that prevents oil adsorption onto the surface of the cylindrical applicator may be wrapped around the entire cylindrical applicator 7 in Fig. 8 to cover the surface of the cylindrical applicator 7, or it may be wrapped so as to cover only the lower portion of the cylindrical applicator 7 in Fig. 8 that comes into contact with excess cosmetic material 5. When covering the surface of the cylindrical applicator with a layer made of a material that has oil-resistant properties, the film wrapped around the surface of the cylindrical applicator may be secured with double-sided adhesive tape only to the upper portion of the cylindrical applicator 7 that does not come into contact with excess cosmetic material 5. Furthermore, even when covering only the lower portion of the cylindrical applicator 7 that comes into contact with excess cosmetic material 5, the film can be secured with double-sided adhesive film only to the portion that does not come into contact with excess cosmetic material 5. As a means for fixing the film to the cylindrical applicator, other known means for fixing a film to an object (such as a clamping member such as a clip, or fixing with an adhesive) can be used instead of using double-sided tape.

[0035] Here, we explain why it is essential that the surface be made of a film or layer of a material that has oil-resistant properties. A sunscreen agent is applied to a quartz plate that has been made superhydrophilic by corona discharge using a stainless steel applicator with the shape shown in Figure 4, and a coating film is prepared whose thickness is confirmed to be consistent using a rotary film thickness meter. This coating film is analyzed using an infrared imaging microscope (Thermo Scientific iN10MX Infrared Imaging System All-in-One Microscope FT-IR) to measure the absorption wavenumber of 2852 cm, which is one of the characteristic absorption wavenumbers of ultraviolet absorbers. -1 Imaging of the UV absorber revealed that the concentration of the UV absorber varied from area to area. This indicates that the assumption that the composition of the sunscreen agent in a cosmetic product is constant regardless of its location on the coating film is invalid. In other words, when a stainless steel applicator was used, the measurement values ​​contained significant error. If it were possible to apply the UV absorber using a material that does not vary the concentration of UV absorber from area to area, error could be significantly reduced, enabling accurate measurements. Therefore, we applied various materials and measured the distribution of the UV absorber in the resulting coating film using an infrared imaging microscope. We found that when a material with an oil-resistant surface was used, the concentration of the UV absorber did not vary from area to area, or only slightly. Conversely, since the coating film remained uniform with these materials, the reason for the UV absorber concentration varying from area to area is likely due to the lipophilic nature of stainless steel, which gradually adsorbs the oily components of the sunscreen agent onto the stainless steel surface as the applicator moves. Once the amount of adsorption reaches a certain level, it falls off to the substrate.

[0036] (About the coating process in general) The coating process 1 described above is a pre-coating process for coating process 2. The stability of the thickness of the film that can be coated by the applicator in coating process 2 tends to depend on the amount of cosmetic on the front surface of the applicator. Therefore, coating process 2 is performed to maintain a consistent amount of cosmetic. In actual use, users spread cosmetics such as sunscreen with their fingers or hands, so coating process 2 reflects physical effects such as shear to reduce the thickness. However, if the time required for coating process 2 is long, the volatile components in the cosmetic will evaporate and the non-volatile components of the cosmetic will become concentrated. Therefore, to ensure uniform coating even for cosmetics that are difficult to apply, the coating time is set to 8 to 14 seconds. Coating process 3 is performed to convert the unevenness of the cosmetic that occurred in coating process 2 into a uniform coating film.

[0037] [Table 1]

[0038] (drying process) After the coating step 3, the product is left in a cool, dark place for 1 hour to 1.5 hours. At this time, ultraviolet light may be irradiated. In countries other than Japan, commercially available sunscreens have SPF values ​​between 100 and 150, and the performance of current SPF analyzers is insufficient to measure these cosmetics. An ultra-sensitive spectrophotometer capable of stable measurement of absorbance up to about 5.5 is required, but the positioning of the integrating sphere and the light path of such an ultra-sensitive spectrophotometer requires the sample to be placed vertically. Therefore, a certain drying period is required to prevent the coated sample from dripping.

[0039] [Measurement of the ultraviolet absorption spectrum of the measurement sample] (Process for measuring the absorption spectrum of the cosmetics applied to each substrate using an ultra-sensitive spectrophotometer) A 150 mm integrating sphere was installed on a PerkinElmer UV-Visible Spectrophotometer LAMBDA 850+ (measurement sensitivity: absorbance 8). The assembled cell for the measurement sample was fixed so that it aligned with the central hole of the anodized aluminum jig shown in Figure 3, as shown in the external view of the assembled cell installed on the spectrophotometer installation jig. This jig was fixed with double-sided tape to the outside of the light-receiving section of the integrating sphere so that it was parallel to the opening of the integrating sphere. This device was used to measure absorbance in the range of 290 to 400 nm. The reason for using the LAMBDA 850+ UV-Visible Spectrophotometer is that resources.perkinelmer.com provides a measurement example of the PerkinElmer LAMBDA 850+ and the LAMBDA 1050+, which has equivalent performance in the UV range, in Materials Characterization: UV / Vis / NIR Spectroscopy; A Spectroscopic in vitro Method for the Calculation of Sunscreen SPF Values. In other words, measuring UV protection capacity using this device already has a proven track record.

[0040] This procedure was carried out for each of the three types of measurement samples (lipophilic substrate, intermediate substrate, and hydrophilic substrate). It is preferable to obtain data from three different measurement locations per measurement sample. A sample with a reference thickness (reference film thickness) is obtained as follows.

[0041] [B. Step of determining the absorbance of a cosmetic material at a standard thickness using an assembled cell and determining the SPF value and UVA-PF value using the following formula (for cosmetic materials other than solid cosmetic materials)] (Filling the sample into the assembly cell) A jig was prepared to hold an assembled cell (Tosoh T-20-UV-0.1) with an internal space thickness of 100 μm, and the female mold of the assembled cell (the cell with the recessed portion) was placed in the cell. After pouring the sample into the recessed portion (100 μm deep) of the cell, a 100 × 100 mm smooth quartz plate was slowly pressed down from above to remove any air bubbles. Since the cell and quartz plate were parallel in this state, the quartz plate was shifted horizontally to obtain a reference film thickness sample in which the assembled cell was filled with the sample to a thickness of 100 μm. The periphery and back of the cell were then cleaned. The reason for using a thickness of 100 μm is that when measuring emulsions at a thickness of 50 μm, the measured absorbance often varies significantly depending on the measurement position. This is due to the large variation in the component composition of the emulsion at a thickness of 50 μm. On the other hand, at a thickness of 500 μm, there is no variation in absorbance depending on the measurement position when measuring various cosmetics, but for cosmetics with high SPF values, the absorbance becomes too large and the Beer-Lambert law may not be satisfied.At a thickness of 100 μm, there is variation in absorbance depending on the measurement position, but this can be corrected by multiple measurements, so an assembly cell with a thickness of 100 μm was selected as the reference thickness. In addition, the reason why the method of filling the assembled cell with the sample involves aligning the cell with a smooth quartz plate so that it is parallel to the cell is that when scraping the surface of the assembled cell using the scraping method (a method in which a quartz plate is placed at an angle to smooth the surface of the assembled cell), it was found that more than the intended amount of some cosmetics was scraped off, resulting in a thickness of approximately 80 to 90 μm, and this method was developed to avoid this.

[0042] (Heating process for reference film thickness sample) A precision hot plate was prepared and stabilized at 60°C. The above-mentioned reference film thickness sample was placed on the hot plate and left for 15 minutes. After 15 minutes, the sample was removed to obtain a reference film thickness sample. Typically, when measuring multiple reference film thickness samples professionally, approximately 10 assembly cells are placed on the hot plate at the same time. Therefore, it is necessary to use a hot plate for physicochemical use that allows precise temperature control to prevent uneven heating. Furthermore, it is preferable to use a large hot plate to avoid sample mix-ups.

[0043] The reason for heating the standard thickness sample is that the thickness of the cosmetic material in the standard thickness sample is 100 μm, so even if left unheated for an hour, the state of the cosmetic material on each of the coated substrates described above would differ. This, in particular, would result in changes in the amount of residual volatile components. Therefore, when measurements were taken using several cosmetics, for example, Figure 2, which shows the relationship between heating time and absorbance for a certain sunscreen at 60°C, shows that the absorbance does not change significantly after 5 minutes of heating, after which volatile components such as water and ethanol have mostly evaporated. Figure 2 shows absorbance measurements at different heating temperatures. Two samples were obtained after 15 minutes of heating, and the absorbance of each was measured. However, because it was found that some cosmetics require a longer heating time, a 15-minute heating period was used to allow for ample heating time to fully remove the volatile components in the cosmetic material. Note that Figure 2 shows two 15-minute measurements. The reason for the large decrease in absorbance after 5 minutes of heating is that in emulsions, light is refracted at the interface between water and oil, causing light scattering (which makes it appear white in visible light), and when the water is removed by heating, this scattered light decreases, resulting in a decrease in absorbance.

[0044] (Spectrophotometer measurement process of standard film thickness sample) The assembled cell is small, measuring 12.5 x 45 mm, and therefore cannot be set in the spectrophotometer as is. Therefore, a black plastic jig, as shown in Figure 3, was developed and installed so that the assembled cell could be placed in close contact with the opening of the integrating sphere of the spectrophotometer. The assembled cell was placed in the opening of the black plastic jig, and absorbance at a wavelength of 400 nm was measured. The reason for placing the assembled cell in close contact with the opening of the integrating sphere is that cosmetics tend to scatter light, and if the assembled cell is not placed in close contact with the integrating sphere, the effects of scattered light cannot be fully reflected. The reason for using 400 nm light is that it is the closest to visible light within the 290-400 nm wavelength range used to measure ultraviolet light and is the wavelength least affected by light scattering by fine particles. While wavelengths such as 660 nm could be used to measure the whiteness of cosmetics alone, they must be measured separately from the 290-400 nm wavelength range when measuring the substrate. Therefore, considering the time limit of measuring the substrate within 1-1.5 hours after coating, using 400 nm is more efficient. Furthermore, some cosmetics, such as lotions, do not absorb or scatter light at 400 nm. In such cases, the measurement wavelength is gradually shifted toward shorter wavelengths, such as 380 nm, 360 nm, 340 nm, 320 nm, and 300 nm, to select a wavelength that yields significant differences in absorbance.

[0045] In order to correct for measurement variations in the assembly cell, it is preferable to measure the absorbance at two different locations within the assembly cell. Furthermore, since it has been found that there are cosmetics for which variations occur in the preparation of standard thickness samples, it is necessary to prepare standard thickness samples multiple times. A preferred example is to prepare two standard thickness samples, measure two locations within each assembly cell to obtain four absorbance data sets, calculate the standard deviation / average value, and if this exceeds 0.2, add another standard thickness sample to obtain the average of the six absorbance values, which is then used as the absorbance for the 100 μm thickness of the corresponding product.

[0046] The absorbance of the sample at 100 μm was determined by the above procedure, and this was converted to 20 μm by multiplying it by 0.2. This is equivalent to 2 mg / cm on the human back in the in vivo SPF measurement method. 2 The measurements were taken by applying the cosmetic material at a rate of 2 mg / cm 2 This is an operation to compare values ​​at a thickness of 20 μm, which corresponds to

[0047] [C. A step of selecting the measurement sample with the highest SPF value based on the SPF values ​​obtained for multiple measurement samples, and determining the SPF value and UVA-PF value of that measurement sample as the in vitro SPF value and in vitro UVA-PF value of that one cosmetic product (cosmetics other than solid cosmetics)] For each of the aforementioned substrates, there are nine absorbance data points. For example, if the absorbance at 400 nm is used as the reference, the nine 400 nm absorbance values ​​are compared with the 20 μm absorbance values ​​measured using the assembly cell described above, and the entire measurement data is corrected to the 20 μm value. The correction method is simply to calculate the ratio of the 400 nm absorbance to the 20 μm absorbance for each wavelength. The average of the corrected data for each wavelength is calculated for each substrate, yielding a single spectral data set for each substrate. This is then used to calculate the in vitro SPF value and in vitro UVA-PF value. The substrate with the highest SPF value among the three substrates is then selected, and the SPF and UVA-PF values ​​for that substrate are determined as the values ​​for that product. Suppose that the applied cosmetic layer is affected by the hydrophilicity (lipophilicity) and other properties of the substrate surface, causing phase separation or dewetting of the cosmetic. As a result, ultraviolet light is more easily transmitted through the entire substrate. In other words, a substrate with a uniform cosmetic layer and minimal ultraviolet light transmittance is the substrate with the highest SPF value (substrate for evaluating ultraviolet transmittance ratio). On such a substrate, the cosmetic layer is formed without the cosmetic composition changing its properties, as compared to other substrates. Therefore, by selecting a substrate with the highest SPF value and then determining the SPF value and UVA-PF value, the inherent properties of the cosmetic can be accurately measured.

[0048] [D. A process of determining the in vivo SPF equivalent value of the one cosmetic product from the equation relating the in vivo SPF value and the in vitro SPF value, and further determining the in vivo UVA-PF equivalent value of the one cosmetic product from the equation relating the in vivo UVA-PF value and the in vitro UVA-PF value (common to cosmetics other than solid cosmetics, powder cosmetics, and stick-type cosmetics)] When calculating in vitro SPF values ​​and in vitro UVA-PF values ​​from spectral data, the cosmetics industry often uses the ISO standard calculation formula described in Non-Patent Document 4. However, research by the present inventors (Miyuki Fujishiro, Shoichi Yahagi, Akihiro Kuroda, Taisuke Banno, Kouichi Asakura, “Investigation on the validity of in vitro UVA-PF evaluation method for sunscreen samples,” 2nd World Congress of Oleoscience (WCOS 2022)) showed that the ISO calculation formula may not adequately reflect differences in absorbance in the UVB region. Furthermore, based on measurements of 206 commercially available sunscreens worldwide, when examining the relationship between the UV protection values ​​or indicators displayed on the products using the ISO standard calculation formula for both SPF and UVA-PF values ​​and the calculated values ​​obtained by the present invention, it was found that the coefficient of determination (R-squared value) of the linear regression model was very poor. On the other hand, before the ISO standard formula was proposed (1979), another formula had been proposed mainly in the Middle East and South America (Elizangela AbreuDutra et al., "Determination of sun protection factor (SPF) of sunscreens by ultraviolet spectroscopy", Brazilian Journal of Pharmaceutical Sciences, 40, 3, 381-385, 2004). This formula calculates the SPF for each wavelength using the following formula: SPF=CF×ΣEE(λ)×I(λ)×Abs(λ) (Formula 1) The SPF calculated for each wavelength was calculated in the range of 290 to 320 nm, and these values ​​were integrated. Here, CF is the correction factor (=10), EE is the erythema action spectrum, I is the solarintensity spectrum, and Abs is the absorbance of the sunscreen product. CF, EE, and I are constants, and EE is shown as a value for each wavelength as the erythema action spectrum in the table in APPENDIX I of Non-Patent Document 4 shown in Figure 17, and I is shown in the same table as the UV-SSR source Wm -2 nm -1 Since the numerical values ​​for each wavelength are shown as , this was used. When the SPF value was calculated using this formula 1, a much larger coefficient of determination was obtained compared to the calculation formula of the ISO standard. Furthermore, since the results of formula 1 were more consistent with human measurements, this formula 1 was used in the present invention (the coefficient of determination of the ISO standard was 0.5336, while that of formula 1 was 0.6792). Also, the following formula UVA=CF×ΣEE(λ)×I(λ)×Abs(λ) (Formula 2) The UVA was determined for each wavelength in the range of 320 to 400 nm, and the values ​​determined for each wavelength were integrated to calculate the UVA index. Here, CF, EE, and I are the same as in the above (Equation 1), where EE is the erythemal effect spectrum, I is the solar intensity spectrum, and Abs is the absorbance of the sunscreen product. These are similarly shown in the table in APPENDIX I of Non-Patent Document 4 shown in FIG. 17. When UVA was calculated using this Equation 2, a much larger coefficient of determination was obtained compared to that obtained from the ISO standard calculation formula (the coefficient of determination for the ISO standard is 0.5767, while for Equation 2 it is 0.7900). Therefore, in the present invention, the same calculation formula was used for UVA-PF, but with the wavelength range changed to 320 to 400 nm.

[0049] The in vitro SPF and in vitro UVA-PF values ​​obtained above cannot be directly compared with conventional in vivo SPF or in vivo UVA-PF values. A correlation equation is required to make such a comparison. The equations obtained from measurements of over 200 commercially available sunscreens worldwide (ratios of in vitro SPF and in vivo SPF values, and ratios of in vitro UVA-PF and in vivo UVA-PF values) are shown below (the relationship between in vivo SPF and in vitro SPF values, and the relationship between in vivo UVA-PF and in vitro UVA-PF values), which can be used to calculate the in vivo SPF equivalent and the in vivo UVA-PF equivalent. The relationship between in vivo SPF and in vitro SPF is: in vivo SPF equivalent = in vitro SPF / 0.101 (Equation 3) The relationship between in vivo UVA-PF value and in vitro UVA-PF value is: in vivo UVA-PF equivalent value = in vitro UVA-PF value / 2.13 (Equation 4) In addition, the above measurements of over 200 commercially available sunscreens from around the world were compared using both the sunlight spectrum defined by the American Association of Textile Science and Technology (AATCC) and the UV-SSR defined by ISO. The results showed that there was little difference in the UVA-PF results, but the AATCC coefficient was slightly higher. It seems that it doesn't really matter which one you use. If you want to calculate using the UV-SSR light source defined by the ISO method, you can use the formula: UVA-PF: in vivo UVA-PF equivalent value = in vitro UVA-PF value / 3.6680.

[0050] Here, we explain how to calculate the equations (the relationship between in vivo SPF values ​​and in vitro SPF values, and the relationship between in vivo UVA-PF values ​​and in vitro UVA-PF values) derived from the measurement results of over 200 commercially available sunscreens worldwide (the ratio of in vitro SPF values ​​to in vivo SPF values, and the ratio of in vitro UVA-PF values ​​to in vivo UVA-PF values). These equations statistically process the relationship between the SPF and UVA-PF values ​​determined in steps A through D above and the UVA-PF value labeled on the product. Currently, in vivo values ​​measured on humans are used internationally for SPF. Regarding UVA-PF, some manufacturers display actual values ​​on the packaging, while others use the PA classification, but all use in vivo values ​​measured on humans. If a UVA-PF value is listed, it can be used as is. However, if a PA classification is listed, a range of in vivo UVA-PF values ​​is specified. Therefore, in this invention, the midpoint of the range is used as the in vivo UVA-PF value corresponding to the PA classification. Specifically, for PA+, the in vivo UVA-PF value is 3, for PA++, 6, for PA+++, 12, and for PA++++, 24. The in vitro SPF values ​​of all products were determined using the method of this invention, and these values ​​are plotted on the vertical axis, while the in vivo SPF value listed on the package is plotted on the horizontal axis. A linear approximation through the origin was performed to determine the approximation formula and coefficient of determination. Based on this method, the relationship between in vivo SPF and in vitro SPF values, as shown in Equation 3 above, was determined. In the same way, the in vitro UVA-PF values ​​of all products were calculated, and these values ​​were plotted on the vertical axis and the in vivo UVA-PF values ​​shown on the packaging on the horizontal axis. A linear approximation was performed passing through the origin, and the approximation formula and coefficient of determination were determined. Finally, the relationship between the in vivo UVA-PF values ​​and the in vitro UVA-PF values, as shown in Equation 4 above, was determined.

[0051] Using the above method, it is possible to prepare a standard film thickness sample of 100 μm using an assembly cell and measure the absorbance of common emulsions, lotions, and spray products, including makeup cosmetics such as liquid foundation. Furthermore, the substrate that maximizes the SPF value is selected, and the in vivo SPF equivalent value and the in vivo UVA-PF equivalent value can be determined through calculations using the above formulas (1) to (4). Next, we will explain the specific procedures for measuring powder cosmetics such as non-fluid powder foundations and stick-type cosmetics. The subsequent methods for determining the in vivo SPF equivalent and in vivo UVA-PF equivalent values ​​are the same as for the fluid cosmetics mentioned above.

[0052] [B. Step of determining the absorbance of a cosmetic material at a standard thickness using an assembled cell and determining the SPF value and UVA-PF value using the following formula (powder cosmetic material)] (Filling the sample into the assembly cell) Place a glass or ceramic plate on top of the balance and place the powdered cosmetic product in a doughnut shape on top. Glass or ceramic plates with a smooth surface approximately 12 cm square are preferred because they are lightweight and easy to work with. Remove any loose powder thoroughly with a brush. Approximately 1.5 g of powder cosmetic product is required per plate, and this weight is accurately measured and recorded. Using a dropper, drop approximately 1.5 g of a non-volatile oil that does not absorb in the ultraviolet range into the hole of the donut, and accurately measure and record the resulting weight. Non-volatile oils that do not absorb in the ultraviolet range are preferably non-polar oils or ester oils that easily mix with the cosmetic product, with squalane being particularly preferred due to its international availability and consistent quality. The non-volatile nature of a product refers to its low or no volatility at room temperature and pressure, generally indicating a weight fluctuation of less than 0.1% over a 10-minute period. The viscosity of the non-volatile oil used in the present invention is not particularly limited, but a viscosity of approximately 6 to 1000 cs is easy to handle. Furthermore, it is preferable to use a top-loading balance capable of measuring 1 mg. After weighing, the mixture is thoroughly mixed on a glass or ceramic plate using an art spatula until no lumps remain and a uniform paste forms. It is important to mix the mixture little by little, rather than trying to mix everything at once. Also, check the mixture at the end, as some of the powder cosmetic may not be well mixed and may adhere to the back of the spatula. Once the mixed paste is complete, pour the entire amount onto the substrate, and then perform the above coating steps 1 to 3 in order. The surface of the applicator used in coating step 3 should have a surface irregularity height of 1.0 μm or less on the part that comes into contact with the cosmetic. The drying step is then omitted, and the spectrophotometer measurement step is carried out. The same applies to solid cosmetics that are not powders.

[0053] For the reference thickness sample, a mixed paste was obtained in the same manner as for the liquid cosmetic, except that the amount of the powder cosmetic and the non-volatile oil that does not absorb in the ultraviolet range were approximately 1 g and 1 g, respectively. Then, as with the liquid cosmetic, the paste was placed in the recess of the assembly cell, left for several minutes, and then the assembly cell plate was placed on top and pressed down. Holding the short edge of the assembly cell with the fingers, the paste that had leaked out around the periphery was wiped away. Slowly apply pressure from one of the long edges of the assembly cell plate to remove as many air bubbles as possible. Since the most significant cause of measurement value variation in powder cosmetic sample preparation is the presence of air bubbles introduced during mixing, when the obtained sample is held up to the light, if air bubbles are found, the area should not be measured, and the spectrophotometer measurement process for the 100 μm reference thickness sample was carried out. Furthermore, when placing a large amount of paste in the recess of the assembly cell, pressing the plate down will help remove air bubbles. At least two sets of reference thickness samples were prepared.

[0054] Next, for each substrate and standard film thickness sample, the adjusted absorbance obtained by dividing the absorbance value obtained by the weight of the powder cosmetic / (weight of the non-volatile oil + weight of the powder cosmetic) is used as the absorbance of that sample, and other steps are carried out in the same manner as the spectrophotometer measurement process for the standard film thickness sample in the case of cosmetics other than solid cosmetics, thereby obtaining measured values ​​for the powder cosmetic and determining the in vivo SPF equivalent value and in vivo UVA-PF equivalent value.

[0055] [B. Step of determining the absorbance of a cosmetic material at a standard thickness using an assembled cell and determining the SPF value and UVA-PF value using the following formula (stick-type cosmetic material)] (Filling of sample into assembled cell) Next, we will explain the procedure for measuring stick-type cosmetics such as lipstick and stick sunscreen. For stick-type cosmetics, it is recommended to first measure the substrate and then the reference film thickness sample. This is because many cosmetics do not absorb or scatter light at a wavelength of 400 nm, so the measurement wavelength to be used for measuring the reference film thickness sample must be determined from the substrate measurement results. Place a glass or ceramic plate on a balance and use a spatula to rub approximately 0.6 g of stick-type cosmetics onto the plate in a square shape. Accurately measure and record the amount of cosmetics. Next, drop approximately 2.4 g of a non-volatile oil that does not absorb in the ultraviolet range into the center of the square shape and similarly measure and record the amount. Mix the ingredients little by little using an art spatula. Once thoroughly mixed, transfer the mixed paste to a container such as a disposable aluminum cup for food use and heat it on a hot plate at 60°C for 15 minutes. During this process, check the back of the spatula to see if any incompletely mixed cosmetics have adhered to it. If phase separation occurs after heating, mix thoroughly while the mixture is still warm. The entire amount of the mixed paste is poured onto the substrate, and the above-mentioned coating steps 1 to 3 are carried out in order. The height of the irregularities on the surface of the applicator used in coating step 3, which comes into contact with the cosmetic, is 1.0 μm or less. Next, the drying step is omitted, and the spectrophotometer measurement step is carried out.

[0056] For the reference film thickness sample, a mixed paste is obtained in the same manner as for the preparation of the reference film thickness sample for the powder cosmetic, except that the amount of stick-type cosmetic to be applied is approximately 0.3 g and the amount of non-volatile oil that does not absorb in the ultraviolet region is approximately 1.2 g. Two or more sets of reference film thickness samples are prepared in the same manner as for the powder cosmetic.

[0057] Next, for each substrate and standard film thickness sample, the absorbance value obtained is divided by the weight of the stick cosmetic / (weight of the non-volatile oil + weight of the powder cosmetic) to obtain an adjusted absorbance, which is used as the absorbance of that sample, and measurements for a film thickness of 100 μm for the stick cosmetic are obtained using the same method as for preparing the standard film thickness sample for the powder cosmetic.In this process, the height of the irregularities is also 1.0 μm or less.

[0058] In this invention, the spectrophotometer measurement process uses a highly sensitive measuring device with a measurement sensitivity of 8 absorbance. However, the cosmetics industry has traditionally used measuring devices known as SPF analyzers. There are two typical models: one with an absorbance sensitivity of 2 and the other with an absorbance sensitivity of 3. As mentioned above, there are examples of measurements with an absorbance of 8. While differences vary by product, the method of this invention appears to be feasible without sensitivity issues for products with an SPF of 15 or less using the two existing models. For products with SPF values ​​higher than this, some measurement values ​​can be obtained, but it is best to assume that they contain significant error factors. As reported at WCOS 2022, we have confirmed that absorbance values ​​displayed by different measuring devices differ significantly when the absorbance exceeds 2. Therefore, the objectivity of measurements cannot be guaranteed unless the sensitivity issues of the measuring device are fully recognized.

[0059] The issue of substrate smoothness is also worth mentioning. In the cosmetics industry, the need for uneven measurement substrates has led to the development of such substrates, reflecting the texture and unevenness of human skin. In contrast, the present invention determines the relationship between the measurements obtained from the in vivo SPF measurement method and the in vivo UVA-PF measurement method and the in vitro SPF and UVA-PF values ​​obtained by the method of the present invention (using the in vivo SPF equivalent calculation formula and the in vivo UVA-PF equivalent calculation formula). This method determines the in vivo SPF and UVA-PF equivalent values ​​without directly using the in vitro SPF and UVA-PF values. In the in vivo method, measurements are performed by firmly pressing a UV irradiation probe against a human back. https: / / solarlight.com / product / model-601-multiport-spf-testing-6-output-solar-simulator / is a catalog for the UV irradiation device most commonly used for contract testing, and indicates the use of a six-port irradiation probe. The UV irradiation section of this probe is cylindrical, with UV light guided through an optical fiber irradiating from the center. When an 8mm cylinder is pressed firmly against human skin, the skin is stretched to its maximum extent and flattened. In this invention, we seek the relationship with the measurement results in this flat state, so we use a smooth measurement substrate. The uneven plate is suited to measuring the effects of UV rays that consumers are exposed to in real life, rather than the in vivo measurement method described above, and it is believed that comparison with existing in vivo measurement methods is inherently difficult. [Example]

[0060] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0061] [Reason why the surface of the applicator used in coating process 3 that comes into contact with the cosmetic should be formed with a material layer that prevents oil adhesion] Test to confirm the change in the coating film when an oil-resistant material layer is applied to the coating part of the applicator and when it is not applied (Measurement conditions) An infrared imaging microscope (Thermo Scientific iN10MX Infrared Imaging System All-in-One Microscope FT-IR) was used, with a measurement interval of 100 μm × 100 μm and a measurement wavenumber of 2852 cm -1 The transmittance measurement using liquid nitrogen and integration were performed 16 times at each measurement point, and a synthetic quartz plate was used as the reference. The measurement range was 70 mm in the direction of the applicator's movement. This device originally obtained the results of mapping analysis in color, but in this patent, white areas indicate higher density (lower transmittance). Measurement sample: Water, zinc oxide, ethanol, ethylhexyl methoxycinnamate, isocetyl myristate, glycerin, propylene glycol, bis-ethylhexyloxyphenol methoxyphenyl triazine, polyhydroxystearic acid, phenoxyethanol, methicone, xanthan gum, fragrance, EDTA-2Na, biosaccharide gum-1, colorant, (sodium acrylate / sodium acryloyldimethyl taurate) copolymer, isohexadecane, polysorbate 80, and sorbitan oleate emulsion (a formulation obtained by selecting and adjusting the components based on the infrared spectrum of each component so that the behavior of the ultraviolet absorber (oil layer) would be clear in infrared observation). Applicator: A cylindrical applicator with a stainless steel surface and a cylindrical applicator with various material layers fixed to the surface were used. Coating conditions: Coating was carried out at a speed of 5 mm / s using a precision coating device. Substrate used for coating: The surface of a 10 x 10 cm synthetic quartz plate was treated for 90 seconds using a corona discharge device (BD-20AC Laboratory Corona Treater manufactured by Electro-Technic Products). The treatment was carried out using a robot to ensure uniformity over the entire surface. Measurement of film thickness: Measurement was performed using a rotary film thickness meter.

[0062] (Test results) Figure 10 shows the results of observation with an infrared imaging microscope of a coating applied using a stainless steel cylindrical applicator under the above measurement conditions. The area to the right of -15000 is the portion of the coating typically used in evaluation tests of UV protection performance. A rotary film thickness meter confirmed that this area had a consistent film thickness. The white areas in Figure 10 are areas where the concentration of UV absorber is relatively high. This shows that even if a coating appears to be of consistent and uniform thickness, the concentration of UV absorber is not consistent. Figure 11 shows the results of observation with an infrared imaging microscope of a coating film coated using an applicator similar to the cylindrical applicator described above, except that a hydrophilized polyethylene terephthalate film was fixed to the surface that comes into contact with the cosmetic. No areas with high concentrations of UV absorbers were observed, indicating that stable coating had been achieved. Furthermore, the results of observation with an infrared imaging microscope when a polyethylene terephthalate film that had not been hydrophilized are used are shown in Figure 12. It can be seen that without hydrophilization, there are variations in the concentration of the UV absorber.

[0063] The results of observation with an infrared imaging microscope of a coating film applied using an applicator with a polyimide tape attached are shown in Figure 13. It can be seen that the concentration of the UV absorber varies greatly. Figure 14 shows the results of observation with an infrared imaging microscope of a coating film applied using an applicator with a fixed polyvinyl chloride tape. It can be seen that the concentration of the UV absorber varies greatly. The results of observation with an infrared imaging microscope of a coating film applied using an applicator with a fixed silicone rubber are shown in Figure 15. It can be seen that the concentration of the UV absorber varies greatly. The results of observation with an infrared imaging microscope of a coating film applied using an applicator with a fixed PEN film are shown in Figure 16. In particular, no areas with high concentrations of UV absorber were observed, indicating that stable coating had been achieved. In this way, various materials were selected based on whether or not they had high-concentration areas, and it was found that PEN and hydrophilized polyethylene terephthalate had excellent coating uniformity.

[0064] Example 1 This section shows an example of the series of steps required to obtain the in vivo SPF equivalent value and in vivo UVA-PF equivalent value of this product using an emulsion cosmetic product consisting of the ingredients shown in Table 2. The UV protection ability of the emulsion shown in Table 2 was measured using humans, with an SPF value of 56 and a UVA-PF of 19.9. The spectrophotometer used was a PerkinElmer UV-visible spectrophotometer LAMBDA 850+ (measurement sensitivity absorbance 8) equipped with a 150 mm integrating sphere, and the assembly cell used was a Tosoh T-20-UV-0.1. The drying time for each substrate was 1 hour. In coating process 1, a 500 μm stainless steel four-sided applicator was used to flatten the emulsion cosmetic. Next, in coating process 2, a sponge urethane (15 mm wide, 10 mm high, 35 mm long) was used as the coating tool attached to the tip of the rotating device, and the rotational coating speed was 260 rpm, and the coating was stretched for 12 seconds. In coating process 3, PEN was used as the coating material for the cylindrical applicator (the cross section of the part that comes into contact with the cosmetic during application is a curved surface that reflects a circle with a diameter of 12 mm), and the gap with each substrate was 25 μm. The three types of substrates used were an acrylic polyisocyanate-treated plate (contact angle of 80° after one week of application of acrylic polyisocyanate), a hydroxyalkyl cellulose-treated plate (contact angle of 51°-52° after one week of application of hydroxyalkyl cellulose), and an inulin-coated plate (inulin-coated quartz plate) (contact angle of 23°-26° after one week of application of inulin). Note that these contact angles are those of pure water at 25°C.

[0065] [Table 2]

[0066] As substrates for evaluating UV transmittance ratios of multiple types with different contact angles, one plate treated with a lipophilic moisture-curing acrylic polyisocyanate (simply referred to as polyisocyanate in the table), one hydroxyalkyl cellulose-coated plate, and one inulin-coated plate were prepared. The emulsion listed in Table 2 was applied to these plates using a stainless steel applicator with a 500 μm gap in coating step 1. Then, in coating step 2, the emulsion was immediately spread at 260 rpm for 12 seconds using a rotating device equipped with a urethane sponge. Then, in coating step 3, a coating film was immediately formed using the PEN-coated cylindrical applicator. After storing the plates in a cool, dark place for 1 hour, the absorbance was measured at three points on each plate using a spectrophotometer.

[0067] Two sets of separately prepared 100 μm-deep assembled cells were filled with the emulsions listed in Table 2. After filling, the cells were placed on a precision hot plate heated to 60°C for 15 minutes and then allowed to cool to room temperature. The absorbance at 400 nm was measured at two points in each assembled cell using a spectrophotometer, for a total of four measurements. The actual absorbance values ​​were 1.174941, 1.159418, 1.277993, and 1.155809. The average absorbance was 1.19204, with a standard deviation of 0.0579, and the standard deviation / average absorbance ratio was 4.9%. Since the standard deviation / average absorbance ratio was 4.9%, which was below 20%, measurements were performed at four points. The average absorbance of 1.19204 is the value at 100 μm, so multiply it by 0.2 for 20 μm to get 0.238408. Using this value as a reference, the spectrum equivalent to a film thickness of 20 μm was calculated by proportional calculation from the absorbance values ​​at 400 nm measured at nine points on each plate.

[0068] Spectral data equivalent to 20 μm was obtained from the nine measurement points as described above. This data was used to calculate the SPF and UVA-PF values ​​according to the above formulas (1) and (2) in Example 1, and the SPF and UVA-PF values ​​according to the ISO method standard calculated in accordance with Non-Patent Document 4 in Comparative Example 1. Note that the calculation formulas (1) and (2) above show values ​​using the solar spectrum data defined by the AATCC as the solar spectrum. The results are shown in Tables 3 and 4.

[0069] [Table 3]

[0070] [Table 4]

[0071] Table 3 shows that the hydroxyalkyl cellulose-coated plate showed the highest SPF value calculated using Equation 1. The in vitro SPF value of this product was approximately 6.8. Similarly, the in vitro UVA-PF value calculated using Equation 2 was approximately 45.9, measured using the same plate. Using Equation 3 to calculate this value yields an in vivo SPF equivalent of 67.7, and using Equation 4 to calculate an in vivo UVA-PF equivalent of 21.6. Since the ISO method requires the use of the exact values, the in vitro SPF value was 296 and the in vitro UVA-PF value was 26.6, resulting in a significant difference between the two. On the other hand, as mentioned above, the in vivo measurements for this product were an SPF of 56 and a UVA-PF of 19.9, demonstrating that the measurement method of the present invention yields values ​​significantly closer to those of the in vivo method than the ISO method used for comparison. Furthermore, when films made of hydrophilic treated polyester, hydrophilic treated polyethylene terephthalate, polyvinylidene fluoride, tetrafluoroethylene, fluorinated ethylene propylene polymer, perfluoroalkoxy polymer, ethylene tetrafluoroethylene copolymer, ethylene chlorotrifluoroethylene copolymer, polychlorotrifluoroethylene, and polyvinyl fluoride were used instead of the PEN, a thin layer made of the emulsion listed in Table 2 and having the same properties as the original properties of this emulsion could be formed on a hydroxyalkyl cellulose coated plate, just as when PEN was used.

[0072] Example 2 Measurements were carried out using a commercially available powder cosmetic (face powder). The SPF value listed on the packaging of the commercially available product was 32, the PA classification was +++ (corresponding to a UVA-PF of 8-16) (the in vivo UVA-PF value corresponding to the PA classification is 12), and the ingredients were listed as follows: Talc,Perlite, Titanium Dioxide, Ethylhexyl Methoxycinnamate, Dimethicone, AluminumHydroxide, Stearic Acid, Silica, Methicone, Caprylyl Glycol,Ethylhexylglycerin, BHT, Cetyl PEG / PPG-10 / 1 Dimethicone, Tocopherol,Pentaerythrityl Tetra-di-t-butyl Hydroxyhydrocinnamate, (+ / -)Titanium Dioxide,Mica, Iron Oxides

[0073] One lipophilic moisture-curing acrylic polyisocyanate-treated plate, one hydroxyalkyl cellulose-coated plate, and one inulin-coated plate were prepared. The powder cosmetic was finely scraped using a spatula and placed in a doughnut shape on a 12 cm square surface-hardened glass plate. The powder cosmetic weighed 1,500 g. 1,500 g of squalane was added to the mixture and mixed thoroughly using an art supplies spatula. The resulting mixed paste was spread on the substrate. This process was repeated three times to obtain samples with the mixed paste spread on the surface of each substrate. Next, in coating step 1, the mixed paste was flattened using a 500 μm stainless steel four-way applicator, as in Example 1 above. Next, in coating step 2, the mixed paste was immediately spread for 12 seconds at 260 rpm using a rotating device equipped with the same urethane sponge as in Example 1 above. Next, in coating step 3, a coating film was immediately formed using the same PEN-coated cylindrical applicator as in Example 1, and the absorbance was measured at three points for each plate using a spectrophotometer.

[0074] Three sets of assembly cells with recesses 100 μm deep were filled with a mixed paste obtained in the same manner as described above, with a powder cosmetic / (powder cosmetic + squalane) ratio of 0.615. The absorbance at 400 nm was measured using a spectrophotometer at two points for each assembly cell, for a total of six measurements. Although four points would be acceptable, six data points were presented here to demonstrate the degree of variability that can occur when measuring powder cosmetics using this method. The measured absorbance values ​​were 4.779588, 4.715465, 4.95402, 4.692718, 5.403312, and 4.901608. The average absorbance was 4.907785167, with a standard deviation of 0.263589873, and a standard deviation / average absorbance = 5.4%. This average absorbance was measured after dilution, so if we assume that the solution is undiluted and divide the average absorbance value by the above mixing ratio, we get 7.980. Using this value, the absorbance values ​​obtained previously at a total of nine points were corrected for film thickness, and the results are shown in Table 4.

[0075] [Table 5]

[0076] [Table 6]

[0077] Looking at Tables 5 and 6, the lipophilic plate showed the highest SPF value calculated using Formula 1. This product's in vitro SPF value was 5.4, and similarly, the in vitro UVA-PF value calculated using Formula 2 was 23.5, measured using the same plate. Using Formula 3 to calculate this value, the equivalent in vivo SPF value is 53.3, and similarly, using Formula 4, the equivalent in vivo UVA-PF value is 11.0. Since the ISO method requires the use of raw values, the in vitro SPF value was 100.6 and the in vitro UVA-PF value was 13.4. Both the in vitro UVA-PF values ​​were in the same range as the product's labeled value, but the ISO method showed a larger difference in SPF value.

[0078] Example 3 Measurements were carried out using a commercially available stick-type sunscreen. The SPF value listed on the package of the commercially available product was 50+, the PA classification was ++++ (corresponding to a UVA-PF of 16-32) (the in vivo UVA-PF value corresponding to the PA classification is 24), and the ingredients were listed as follows: Triethylhexanoin,Isononyl Isononanoate, Polymethylsilsesquioxane, Dimethicone, Nylon-12,Ethylhexyl Methoxycinnamate, Polyethylene, Synthetic Wax,Trimethylpentanediol / Adipic Acid / Glycerin Crosspolymer, ButylMethoxydibenzoylmethane, Dimethicone / Vinyl Dimethicone Crosspolymer, SucrosePolystearate, Polysilicone-15, Menthol, Alumina, Tocopherol, Water, ButyleneGlycol, Saxifraga Sarmentosa Extract, Geranium Robertianum Extract, VacciniumMyrtillus Leaf Extract, Cynara Scolymus (Artichoke) Leaf Extract, BHT,Fragrance

[0079] One lipophilic moisture-curing acrylic polyisocyanate-treated plate, one hydroxyalkyl cellulose-coated plate, and one inulin-coated plate were prepared. A 12 cm square surface-hardened glass plate was rubbed with a painter's spatula in a square pattern. The cosmetic weighed 0.600 g. 2,400 g of squalane was dropped into the center of the square and mixed thoroughly with the spatula. The mixed paste was placed in a disposable aluminum cup for food use, heated at 60°C for 15 minutes, and then poured onto the plate. This process was repeated three times to obtain samples with the mixed paste spread over the surface of each substrate. Next, in coating step 1, the mixed paste was flattened using a 500 μm stainless steel four-way applicator, as in Example 1 above. Next, in coating step 2, the mixed paste was immediately spread for 12 seconds at 260 rpm using a rotating device equipped with a urethane sponge, as in Example 1 above. Next, in coating step 3, a coating film was formed using the PEN-coated cylindrical applicator in the same manner as in Example 1, and the absorbance was measured at three points for each plate using a spectrophotometer.

[0080] Two 100 μm-deep assembly cells were filled with a mixed paste obtained in the same manner as above, with a powder cosmetic / (powder cosmetic + squalane) ratio of 0.208. The above measurements revealed that this cosmetic had almost no absorption at a wavelength of 400 nm and sufficient absorption at a wavelength of 360 nm, so the measurement wavelength was changed to 360 nm. The actual absorbance values ​​obtained were 3.883449, 3.774979, 3.804809, and 3.645621, resulting in four points: an average absorbance of 3.777215, a standard deviation of 0.098943, and a standard deviation / average absorbance = 2.6%. Since this average absorbance was measured using a diluted sample, dividing the average absorbance value by the above blend ratio assuming the sample was undiluted yields 18.2. Using this value, the absorbance values ​​obtained previously for the nine points were corrected for film thickness, and the results are shown in Tables 5 and 6.

[0081] [Table 7]

[0082] [Table 8]

[0083] Table 5 shows that the hydroxyalkyl cellulose-coated plate showed the highest SPF value according to the 0029 standard. This product's in vitro SPF value was approximately 3.2, and its in vitro UVA-PF value, measured using the same plate, was approximately 12.0. Using Equation 3 to calculate this value yields an in vivo SPF equivalent of 31.8, which is similarly calculated using Equation 4 as 5.6. Since the ISO method requires the use of raw values, the in vitro SPF value was 19.5 and the in vitro UVA-PF value was 3.5. Compared to the product's labeled values, the SPF values ​​calculated using Equations 3 and 4 were slightly lower. Although the UVA-PF values ​​were consistent, both values ​​were significantly lower according to the ISO standard.

[0084] (Comparative Example 1, Example 4) Measurements were carried out using a commercially available pressure can type sunscreen spray. The SPF value listed on the package of the commercially available product was 100, and the ingredients were listed as follows: avobenzone(3%), homosalate (10%), octisalate (5%), octocrylene (10%), oxybenzone (6%) alcoholdenat., isobutane, VA / butyl maleate / isobornyl acrylate copolymer, caprylylglycol, cyclopentasiloxane, cyclohexasiloxane, fragrance, polyglyceryl-3stearate / isostearate / dimer dilinoleate crosspolymer, lauryl PEG-8 dimethicone, phenylisopropyl dimethicone, ascorbyl palmitate, methyl dihydroabietate, tocopheryl acetate, mineral oil, panthenol, water, Aloe barbadensis leaf extract.

[0085] One plate was prepared that was treated with the aforementioned lipophilic moisture-curing acrylic polyisocyanate, one plate that was coated with hydroxyalkyl cellulose, and one plate that was coated with inulin. The only coating process involved spraying sunscreen from above and forming a coating film using a stainless steel four-way applicator with a 20 μm gap, moving the applicator at a speed of 5 mm / s. An attempt was made to measure the film thickness using a rotary film thickness meter, but this was not possible because the cosmetic was transparent.

[0086] Therefore, measurements were carried out in accordance with Example 1. A hydroxyalkyl cellulose-coated plate was selected, and the in vitro SPF value was 4.8. Similarly, the in vitro UVA-PF value measured using the same plate was 35.6. The in vivo SPF equivalent value calculated using Equation 3 was 47.8, and the in vivo UVA-PF equivalent value calculated using Equation 4 was also 16.7. The film thickness measurement method using the assembled cell used in the present invention is highly suitable for cosmetics such as transparent lotions and cosmetics that produce a lot of unevenness in the coating film.

[0087] (Comparative Example 2, Example 5) Measurements were carried out using a commercially available sunscreen. The SPF value listed on the package of the commercially available product was 8, and the ingredients were listed as follows: Water,Alcohol, Phenylbenzimidazole Sulfonic Acid, Triethanolamine, Camellia SinensisLeaf Extract, Rosmarinus Officinalis (Rosemary) Leaf Extract, Coix Lacryma-JobiMa-yuen Seed Extract, Aloe Barbadensis Leaf Extract, Dipotassium Glycyrrhizate,PEG-12 Dimethicone, Dipropylene Glycol, PEG / PPG-30 / 10 Dimethicone, Dimethicone,Phenyl Trimethicone, Butylene Glycol, Potassium Hydroxide, Menthol, Fragrance

[0088] One each of the lipophilic acrylic polyisocyanate-treated plate, the hydroxyalkyl cellulose-coated plate, and the corona discharge-treated ultrahydrophilic plate was prepared. Sunscreen was applied from above, and in coating step 1, a cosmetic was applied using a stainless steel four-way applicator with a 500 μm gap, as in Example 1 above. Then, in coating step 2, the coating was immediately spread for 12 seconds at 260 rpm using a rotating device with a urethane sponge attached, as in Example 1 above. Next, in coating step 3, a coating film was formed using a stainless steel four-way applicator with a 20 μm gap, running the applicator at a speed of 5 mm / s, and the film thickness was measured using a rotary film thickness gauge. The film thicknesses were 5, 2, and 1 μm, respectively, for the plates. The SPF values ​​at 20 μm thickness, as determined by the ISO method, were 9, 32, and 63, respectively. When the ultra-hydrophilic plate was treated with corona discharge, most of the cosmetic material adhered to the stainless steel applicator, with some components undergoing phase separation to form a coating film. A similar situation also occurred with the hydroxyalkyl cellulose-coated plate. This was thought to be due to the fact that metal is lipophilic, and if the sunscreen happens to be a cosmetic material with a high affinity for metal, even when the applicator with a narrow gap is run, the sunscreen is not properly separated into upper and lower layers, and most of it ends up on the metal side.

[0089] Therefore, when this product was tested in the same manner as in Example 1, the above problems did not occur with the PEN-coated cylindrical applicator, and a uniform coating film was formed, proving the effectiveness of the polyethylene naphthalate film. We also tested hydrophilically treated polyester film, hydrophilically treated polyethylene terephthalate film, polyvinylidene fluoride film, and a general fluororesin film, and all of them produced a coating film, confirming the effectiveness of the film. On the other hand, when we looked at other film-like materials such as those listed in Table 1, all of them had problems such as problems with the uniformity of the coating film and poor applicator movement.

[0090] From the above test results, it can be seen that the Examples of the present invention solve the problems of the Comparative Examples and are excellent as a measurement method applicable to a wide range of cosmetics. [Explanation of symbols]

[0091] 1: Paint spreading device 2: Paint spreading material 3: Support part 4: Circuit board 5: Excessive cosmetics 6: Tip of paint spreading part 7: Cylindrical applicator 8: Support part 9: Paint spreading device B: Base P: Support S: Resin sponge-like coating tool

Claims

1. A method for evaluating the UV protection performance of cosmetics, comprising a step of preparing a measurement sample for evaluating the UV protection performance of cosmetics, the preparation step comprising a method of forming a uniform cosmetic application layer on the surface of a transparent substrate for measuring UV transmittance using an applicator whose surface is formed of a material layer having oil-resistant properties.

2. 2. The method for evaluating the UV protection performance of cosmetics according to claim 1, wherein the material layer having an oil-resistant surface is a layer made of one or more materials selected from the group consisting of polyethylene naphthalate (PEN) film, hydrophilically treated polyester film, hydrophilically treated polyethylene terephthalate film, and fluororesin film, all of which have oil-resistant properties.

3. A method for evaluating the UV protection performance of a cosmetic preparation according to claim 1 or 2, comprising the following steps A to D: A. A process for preparing multiple measurement samples for evaluating the UV protection performance of cosmetics, in which a single cosmetic is used to form a uniform cosmetic layer on each of multiple types of UV transmittance ratio evaluation substrates with different contact angles, using an applicator whose surface is formed of a material layer with anti-adhesion properties. B. A step of determining the absorbance of a cosmetic material at a standard thickness using an assembled cell, and calculating the SPF value and UVA-PF value using the following formula: SPF value obtained by integrating the wavelengths from 290 to 320 nm in 1 nm increments using the formula CF × ΣEE(λ) × I(λ) × Abs(λ) The UVA-PF value is calculated by integrating the wavelengths from 320 to 400 nm in 1 nm increments using the formula CF x ΣEE(λ) x I(λ) x Abs(λ). where CF is the correction factor (=10), EE is the erythemal effect spectrum, I is the solar intensity spectrum, and Abs is the absorbance of the sunscreen product. C. A step of selecting the measurement sample with the highest SPF value based on the SPF values ​​obtained for multiple measurement samples, and determining the SPF value and UVA-PF value of that measurement sample as the in vitro SPF value and in vitro UVA-PF value of that one cosmetic product. D. A step of determining the in vivo SPF equivalent value of the one cosmetic product from the relational expression between the in vivo SPF value and the in vitro SPF value, and further determining the in vivo UVA-PF equivalent value of the one cosmetic product from the relational expression between the in vivo UVA-PF value and the in vitro UVA-PF value.

4. 4. The method for evaluating the UV protection performance of cosmetics according to claim 3, wherein the plurality of types of transparent substrates for measuring UV transmittance having different contact angles are three types: a transparent substrate for measuring UV transmittance having a layer coated on its surface with polyisocyanate, a transparent substrate for measuring UV transmittance having a layer coated with inulin, and a transparent substrate for measuring UV transmittance having a layer coated with hydroxyalkyl cellulose.

5. The method for evaluating UV protection performance according to claim 3, characterized in that the relationship equation between the in vivo SPF value and the in vitro SPF value, and the relationship equation between the in vivo UVA-PF value and the in vitro UVA-PF value are determined by statistically processing the relationship between the SPF value, UVA-PF value of the cosmetic obtained by the in vivo method, or the in vivo UVA-PF value corresponding to the PA classification, and the SPF value and UVA-PF value determined by steps A to D.

6. 3. The method for evaluating ultraviolet protection performance according to claim 1, wherein the cosmetic is a powder cosmetic, a stick cosmetic, or a paste-like product obtained by mixing a solid cosmetic with a non-volatile oil.

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