Evaluation method

Abstract

To provide an evaluation method capable of simply and quantitatively evaluating makeup deterioration and washability.SOLUTION: An application step of applying a fluorescent substance that is excited by ultraviolet rays to emit visible light to a measurement target to which a cosmetic is applied, or applying a test cosmetic containing a fluorescent substance that is excited by ultraviolet rays to emit visible light to a measurement target; The evaluation method includes a fluorescence image acquisition step of acquiring fluorescence images before and after predetermined processing, and a comparison step of comparing a pre-processing fluorescence area obtained from the predetermined pre-processing fluorescence image with a post-processing fluorescence area obtained from the predetermined post-processing fluorescence image.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an evaluation method that is preferably used for evaluating makeup smearing and cleansing properties. [Background technology]

[0002] Cosmetic smearing is one of the important qualities of cosmetics such as makeup cosmetics, sunscreen cosmetics, etc. As a method for evaluating such cosmetic smearing, for example, a method has been proposed in which the makeup cosmetic is applied to one side of filter paper, an oily component (artificial sebum) is applied to the back side of the filter paper, the gloss value of the surface to which the makeup cosmetic is applied is measured, and the optical change is used as an index (see, for example, Patent Document 1).

[0003] As described above, cosmetics that do not easily smudge during use are required, while cosmetics that have high cleansing properties that allow them to be washed away without remaining on the skin during washing are also required. Methods for evaluating such cleansing properties include, for example, sensory evaluation by a specialist panel or visual evaluation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-130630 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional methods for evaluating makeup smearing and cleansing performance are not fully satisfactory in terms of simplicity and quantitativeness, and there is a demand for an evaluation method that can more simply and quantitatively evaluate makeup smearing and cleansing performance.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an evaluation method that can simply and quantitatively evaluate the makeup smearing of cosmetics and the cleansing properties of cleansers. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present inventors conducted extensive research and found that an evaluation method including the steps of applying a fluorescent substance that is excited by ultraviolet light to emit visible light to a measurement object to which a cosmetic has been applied, or applying a test cosmetic containing a fluorescent substance that is excited by ultraviolet light to emit visible light to the measurement object, a fluorescence image acquisition step of using an ultraviolet irradiation photography means to acquire fluorescence images of the measurement object before and after a predetermined treatment, and a comparison step of comparing the pre-treatment fluorescence area determined from the pre-treatment fluorescence image with the post-treatment fluorescence area determined from the post-treatment fluorescence image, can simply and quantitatively evaluate the makeup breakdown of a cosmetic and the cleansing performance of a cleanser, which led to the present invention.

[0008] The present invention is based on the above findings of the present inventors, and the means for solving the above problems are as follows.

[0009] The evaluation method of the present invention includes an application step of applying a fluorescent substance that emits visible light when excited by ultraviolet light to a measurement object to which a cosmetic has been applied, or applying a test cosmetic containing a fluorescent substance that emits visible light when excited by ultraviolet light to the measurement object; a fluorescence image acquisition step of using an ultraviolet irradiation photography means to acquire fluorescence images of the measurement object before and after a predetermined treatment; and a comparison step of comparing the pre-treatment fluorescence area determined from the predetermined pre-treatment fluorescence image with the post-treatment fluorescence area determined from the predetermined post-treatment fluorescence image. In addition, in the evaluation method, it is preferable that the ultraviolet irradiation photographing means is a combination of an ultraviolet irradiator and a visible light camera, a combination of an ultraviolet irradiator and an ultraviolet camera, or an imaging analysis device having an ultraviolet irradiator, an ultraviolet camera, and an image analysis unit. In the evaluation method, the measurement target is preferably artificial skin or the skin of a subject. In the evaluation method, the fluorescent substance is preferably at least one selected from the group consisting of a composite oxide containing manganese, a composite oxide containing cerium, and fluorescent zinc oxide. In the evaluation method, the application of the fluorescent substance is preferably a method in which a solution containing the fluorescent substance is sprayed. In the evaluation method, the application of the fluorescent substance is preferably a method in which a powder containing the fluorescent substance is applied with a cosmetic brush. In the evaluation method, the application of the fluorescent substance is preferably a method in which a powder containing the fluorescent substance is applied with a cosmetic puff.

[0010] In the evaluation method, the predetermined treatment is preferably a treatment in which the measurement object to which a fluorescent substance has been applied is washed with a detergent. In addition, in the cleaning treatment using the above-mentioned detergent, it is preferable to use a combination of two or more detergents with different compositions. In addition, in the evaluation method, it is preferable that in the comparison step, the fluorescent area remaining rate is calculated based on the following mathematical formula 1 to evaluate the degree of cleanability. [Formula 1] Fluorescence area remaining rate (%) = (B / A) x 100 In the formula 1, A is the fluorescent area before treatment, and B is the fluorescent area after treatment.

[0011] Furthermore, in the evaluation method, the predetermined treatment is preferably a treatment in which the cosmetic material to be evaluated is applied, and then the measurement object to which a fluorescent substance has been applied is left at room temperature for 4 to 6 hours. Furthermore, in the evaluation method, the predetermined treatment is preferably a treatment in which the subject is asked to apply the cosmetic material to be evaluated and then wait quietly at room temperature for 4 to 6 hours after application of the fluorescent substance. In addition, in the comparison step of the evaluation method, it is preferable to calculate the fluorescence area reduction rate based on the following mathematical formula 2 and evaluate the degree of makeup breakdown. [Formula 2] Fluorescence area reduction rate (%) = [(CD) / C] x 100 In Equation 2, C is the fluorescent area before treatment, and D is the fluorescent area after treatment. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an evaluation method that can simply and quantitatively evaluate makeup smearing and cleansing properties. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a flowchart showing an example of the processing flow in the evaluation method of the present invention. [Figure 2] FIG. 2 is a photograph showing a fluorescent image of a subject before the treatment of leaving the subject for 4 hours. [Figure 3] FIG. 3 is a photograph showing a fluorescent image of a subject after the treatment was left for 4 hours. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Evaluation method) The evaluation method of the present invention includes an applying step, a fluorescent image acquiring step, and a comparing step, and may further include other steps as necessary.

[0015] According to the present invention, it is possible to easily and quantitatively (objectively) evaluate makeup breakdown and cleansing properties in an in vitro test using artificial skin, and it is also possible to easily and quantitatively (objectively) evaluate makeup breakdown and cleansing properties in an actual use test by a subject using the subject's skin.

[0016] <Application process> In the application step, a fluorescent substance that is excited by ultraviolet light to emit visible light is applied to the measurement object to which the cosmetic has been applied. In addition, when a test cosmetic containing a fluorescent substance that is excited by ultraviolet light to emit visible light is used as the cosmetic, the test cosmetic is applied to the measurement object. The step of applying a fluorescent substance to the measurement target to which a cosmetic has been applied is suitable when the evaluation target is a cosmetic or a cleanser. The step of applying a test cosmetic to a measurement target is suitable when a cleanser is to be evaluated. Although it is also possible to evaluate a cosmetic, it is preferable to add a small amount of fluorescent substance in that case, since the composition of the cosmetic changes when a fluorescent substance is added.

[0017] In the application step of applying a fluorescent substance to a measurement object to which a cosmetic has been applied, the cosmetic is first applied to the measurement object. Application includes application of the cosmetic by spraying. Here, the cosmetic applied to the measurement object is the cosmetic to be evaluated when evaluating makeup breakdown. The cosmetic is not particularly limited and any cosmetic can be used, but examples include makeup cosmetics such as powder or emulsion type foundation, blush, eye shadow, sunscreen cosmetics, skin care cosmetics such as lotion, serum, emulsion, cream, whitening cosmetics, sunscreen cosmetics, makeup base cream, etc. These may be used alone or in combination of two or more. The amount of cosmetic applied is measured per 1 cm of the object to be measured if the cosmetic is liquid. 2 It is preferable that the amount of the liquid is 1 to 10 μL per area. 2 The amount per area is preferably 0.1 to 1 mg.

[0018] The measurement object may be, for example, artificial skin or the skin of a subject. The artificial skin is preferably human artificial skin. There are no particular limitations on the artificial skin and it can be appropriately selected depending on the purpose, and examples thereof include methyl methacrylate (PMMA) plate, Bioskin plate (manufactured by Viewlux Co., Ltd.), artificial leather "Saplare" (registered trademark) manufactured by Idemitsu Technofine Co., Ltd., VITRO-SKIN (registered trademark) manufactured by Tegara Corporation, and miniature pig skin.

[0019] Next, a fluorescent substance that is excited by ultraviolet light and emits visible light is applied to the measurement object to which the cosmetic has been applied. The fluorescent substance that is excited by ultraviolet light to emit visible light is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include composite oxides containing manganese, composite oxides containing cerium, fluorescent zinc oxide, etc. These may be used alone or in combination of two or more. Examples of composite oxides containing manganese include MnFe2O4, MnCr2O4, MnWO4, MnTiO3, MnSiO4, and MnSiO3. Examples of composite oxides containing cerium include calcium phosphate and cerium phosphate. Fluorescent zinc oxide is obtained by firing zinc oxide in a reducing atmosphere such as H2 or CO (see, for example, Japanese Patent Application Laid-Open No. 5-117127).

[0020] As the fluorescent substance that is excited by ultraviolet light to emit visible light, commercially available products can be used, such as Lumate B (manufactured by Sakai Chemical Industry Co., Ltd.), Lumate G (manufactured by Sakai Chemical Industry Co., Ltd.), and Lumate R (manufactured by Sakai Chemical Industry Co., Ltd.). Lumate B is a fired material of calcium carbonate, calcium pyrophosphate, and cerium, which absorbs ultraviolet light, converts the wavelength to visible light, and emits blue light. LumateG is a fluorescent zinc oxide that absorbs ultraviolet light, converts the wavelength into visible light, and emits green light. Lumate® is a fired product of titanium oxide, magnesium carbonate, and manganese carbonate, which absorbs ultraviolet light, converts the wavelength to visible light, and emits red light.

[0021] The method of applying the fluorescent substance is not particularly limited and can be selected appropriately depending on the purpose. Examples include (1) spraying a solution containing the fluorescent substance onto the measurement target (artificial skin or subject's skin), (2) applying powder containing the fluorescent substance onto the measurement target (artificial skin or subject's skin) with a cosmetic brush, and (3) applying powder containing the fluorescent substance onto the measurement target (artificial skin or subject's skin) with a cosmetic puff.

[0022] In the application step of applying a test cosmetic containing a fluorescent substance to a measurement subject, the test cosmetic is applied to the measurement subject. The fluorescent substance used can be the same as that used in the application step of applying the fluorescent substance to the measurement object to which the cosmetic has been applied. The amount of fluorescent substance added is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, even more preferably 0.3 to 3 parts by mass, and particularly preferably 0.5 to 1 part by mass, per 100 parts by mass of the cosmetic. If the amount of fluorescent substance added is less than 0.05 parts by mass, the amount of fluorescence will be so small that a clear fluorescent image may not be obtained. If the amount of fluorescent substance added exceeds 10 parts by mass, the composition of the cosmetic may change too much, and the fluorescent substance may not be uniformly added to the cosmetic. The test cosmetic may be applied by, for example, painting or spraying.

[0023] <Fluorescence image acquisition process> In the fluorescence image acquisition step, an ultraviolet irradiation imaging means is used to acquire fluorescence images of the measurement object before and after the predetermined processing.

[0024] The predetermined pre-treatment fluorescent image may be acquired before the predetermined treatment is performed on the measurement object, and may be acquired immediately after the fluorescent substance or test cosmetic is applied to the measurement object. When a measurement object (artificial skin or subject's skin) to which a fluorescent substance or test cosmetic has been applied is photographed using an ultraviolet irradiation photography means, the portion to which the fluorescent substance has been applied can be obtained as a pre-treatment fluorescent image. When a measurement object (artificial skin or subject's skin) after a predetermined treatment has been performed is photographed using an ultraviolet irradiation photography means, the portion to which the fluorescent substance remains after the predetermined treatment can be obtained as a post-treatment fluorescent image.

[0025] The ultraviolet irradiation photography means is preferably, for example, (1) a combination of an ultraviolet irradiator and a visible light camera, (2) a combination of an ultraviolet irradiator and an ultraviolet camera, or (3) an imaging analysis device having an ultraviolet irradiator, an ultraviolet camera, and an image analysis unit.

[0026] (1) In the combination of an ultraviolet irradiator and a visible light camera, an ultraviolet lamp or an LED (Light Emitting Diode) that emits light in the ultraviolet wavelength range is used as the ultraviolet irradiator, and a regular visible light camera can be used as the visible light camera. One visible light camera may be used, but multiple cameras may also be installed to capture images. The data captured by the visible light camera is sent to an image analyzer via cable or wirelessly. The image analyzer consists of a personal computer, which draws images according to the fluorescence intensity of the data sent from the camera, forming a fluorescent image.

[0027] (2) In the combination of an ultraviolet irradiator and an ultraviolet camera, an ultraviolet lamp or an LED that emits light in the ultraviolet wavelength region is used as the ultraviolet irradiator. One ultraviolet camera may be used, but multiple ultraviolet cameras may also be installed to take images. The data captured by the ultraviolet camera is sent to an image analyzer via cable or wirelessly. The image analyzer consists of a personal computer, which draws images according to the fluorescence intensity of the data sent from the ultraviolet camera, forming a fluorescent image.

[0028] (3) An example of an imaging and analysis device having an ultraviolet irradiator, an ultraviolet camera, and an image analysis unit is VISIA (registered trademark) Evolution (manufactured by Canfield Scientific).

[0029] Examples of the predetermined treatment include (1) a treatment in which the measurement target is washed with a cleanser, and (2) a treatment in which the measurement target (artificial skin or the subject's skin) is left standing for a predetermined period of time (a leaving treatment).

[0030] (1) The process of washing the measurement object with a cleanser is a process (cleaning process) in which the measurement object (artificial skin or subject's skin) to which a cosmetic or test cosmetic has been applied is washed with the cleanser to be evaluated. This allows the cleansing properties of the cleanser to be evaluated. The cleanser is not particularly limited, and any cleanser that has cleansing properties for cosmetics or test cosmetics can be used, including, for example, foam cleansing cleansers, liquid cleansing cleansers, cream cleansing cleansers, etc. These may be used alone or in combination of two or more. Two or more cleansers with different compositions can be combined for use in a cleansing process, allowing the identification of specific cleanser combinations suitable for cleaning cosmetics.

[0031] (2) The process of leaving the measurement subject for a predetermined period of time involves applying the cosmetic or test cosmetic to be evaluated (artificial skin or subject's skin) and then leaving the measurement subject to which the fluorescent substance has been applied at room temperature (20-25°C) for 4 to 6 hours. This 4 to 6 hours is the time it takes for makeup to naturally start to come off. This allows the degree of makeup coming off to be evaluated. When the subject of measurement is a human subject, the subject is asked to apply the cosmetic to be evaluated and then wait quietly at room temperature (20-25°C) for 4-6 hours after application of the fluorescent substance (sitting quietly in a chair in the room).

[0032] <Comparison process> In the comparison step, a pre-treatment fluorescence area obtained from a predetermined pre-treatment fluorescence image is compared with a post-treatment fluorescence area obtained from a predetermined post-treatment fluorescence image.

[0033] Examples of comparison methods include (1) calculating the fluorescent area remaining rate from the fluorescent area before and after treatment and evaluating the degree of cleansing ability, and (2) calculating the fluorescent area reduction rate from the fluorescent area before and after treatment and evaluating the degree of makeup smearing.

[0034] Specifically, (1) the method for calculating the fluorescence area residual rate and evaluating the degree of cleansing ability involves calculating the fluorescence area residual rate from the pre-treatment (before cleaning treatment) fluorescence area obtained from a predetermined pre-treatment fluorescent image and the post-treatment fluorescent area obtained from a predetermined post-treatment (after cleaning treatment) fluorescent image, based on the following mathematical formula 1, and evaluating the degree of cleansing ability. If the fluorescence area residual rate is less than 30%, the cleanser is evaluated as having good cleansing ability. [Formula 1] Fluorescence area remaining rate (%) = (B / A) x 100 In the formula 1, A is the fluorescent area before the treatment (before the washing treatment), and B is the fluorescent area after the treatment (after the washing treatment).

[0035] (2) The method for calculating the rate of decrease in the fluorescent area and evaluating the degree of makeup breakdown involves leaving the measurement subject at room temperature (20-25°C) for the time it takes for makeup breakdown to occur naturally (approximately 4-6 hours), and then calculating the rate of decrease in the fluorescent area based on the following formula 2 using the pre-treatment fluorescent area obtained from the fluorescent image taken before the specified treatment (before leaving the subject to treatment) and the post-treatment fluorescent area obtained from the fluorescent image taken after the specified treatment (after leaving the subject to treatment). A rate of decrease in the fluorescent area of ​​less than 50% is considered to be less likely to cause makeup breakdown and to have good durability. [Formula 2] Fluorescence area reduction rate (%) = [(CD) / C] x 100 In Equation 2, C is the fluorescent area before treatment (before standing treatment), and D is the fluorescent area after treatment (after standing treatment).

[0036] <Other processes> The other steps are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a data storage step, a display step, and an output step.

[0037] 1 is a flow chart showing an example of the processing flow in the evaluation method of the present invention. The processing flow in the evaluation method of the present invention will be described below.

[0038] In step S101 (application process), a fluorescent substance that is excited by ultraviolet light and emits visible light is applied to the measurement object to which a cosmetic has been applied, or a test cosmetic containing a fluorescent substance that is excited by ultraviolet light and emits visible light is applied to the measurement object, and then processing proceeds to S102.

[0039] In step S102 (fluorescence image acquisition process), the measurement object before and after the specified processing is photographed with an ultraviolet camera, and once fluorescence images before and after the specified processing are acquired, the process proceeds to S103.

[0040] In step S103 (comparison step), the pre-processing fluorescence area calculated from a predetermined pre-processing fluorescence image is compared with the post-processing fluorescence area calculated from a predetermined post-processing fluorescence image, and then this process is terminated.

[0041] As described above, the evaluation method of the present invention makes it possible to simply and quantitatively evaluate makeup smearing and cleansing properties. [Example]

[0042] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0043] Example 1 -Evaluation of the cleaning properties of foam cleansing detergents (in vitro testing)- Three commercially available artificial leathers (Bioskin Plate, manufactured by Bealux) were placed on each of them, with 1cm of liquid foundation (prototype) applied. 2 1 μL was applied per area. Each piece of artificial leather with the cosmetic applied was left to stand for 10 minutes to dry thoroughly, and then 1 cm of Lumate B (manufactured by Sakai Chemical Industry Co., Ltd.), a fluorescent substance that emits visible light when excited by ultraviolet light, was applied. 2 0.0001 g per area was applied using a cosmetic brush, and an image was taken using an ultraviolet camera (ID4MTVISB-CL, manufactured by Idur Corporation) to obtain a fluorescent image before treatment (before washing treatment).

[0044] Next, one push of each of the detergents to be evaluated (Foam Cleansing Detergent 1 (prototype) and Foam Cleansing Detergent 2 (prototype)) was applied and allowed to soak in, and then each piece of artificial leather was wiped off with a tissue and photographed with an ultraviolet camera to obtain a fluorescent image after the treatment (after cleaning treatment).

[0045] Next, the pre-treatment fluorescent area was calculated from the obtained pre-treatment (before washing treatment) fluorescent image, and the post-treatment fluorescent area was calculated from the obtained post-treatment (after washing treatment) fluorescent image, and the fluorescent area remaining rate was calculated using the following formula 1, and the average of the three pieces of artificial leather was calculated, and the degree of cleaning ability of the detergent was evaluated based on the following evaluation criteria. The results are shown in Table 1. [Formula 1] Fluorescence area remaining rate (%) = (B / A) x 100 In the formula 1, A is the fluorescent area before the treatment (before the washing treatment), and B is the fluorescent area after the treatment (after the washing treatment).

[0046] [Evaluation criteria] ×: Fluorescent area remaining rate is 50% or more △: Fluorescent area remaining rate is 30% or more but less than 50% ○: Fluorescent area remaining rate is 10% or more but less than 30% ◎: Fluorescent area remaining rate is less than 10%

[0047] [Table 1]

[0048] The results in Table 1 show that there are differences in cleansing properties depending on the type of cleanser, with Foam Cleansing Cosmetic 1 showing a smaller fluorescence area residual rate than Foam Cleansing Cosmetic 2, demonstrating superior cleansing properties. This demonstrates that the evaluation method of the present invention allows the degree of detergency to be evaluated simply and quantitatively.

[0049] Example 2 -Evaluation of makeup breakdown (actual use test by subjects)- Three subjects (men and women in their 30s) applied 0.2 g of the cosmetics to be evaluated (Liquid Foundation 1 (prototype) and Liquid Foundation 2 (prototype)) to each side of their face. After the cosmetic preparations were allowed to dry for 10 minutes, 0.02 g of Lumate® (manufactured by Sakai Chemical Industry Co., Ltd.), a fluorescent substance that emits visible light when excited by ultraviolet light, was placed on a cosmetic puff and evenly applied to the subject's entire face. Photographs were then taken with an ultraviolet camera (VISIA® Evolution, manufactured by Canfield Scientific) to obtain pre-treatment (before leaving the product on for 4 hours) fluorescent images. Figure 2 shows the pre-treatment fluorescent image of the subject. Liquid foundation 1 is on the left side of Figure 2, and liquid foundation 2 is on the right side.

[0050] Next, each subject was asked to wait (leave) quietly in the testing room at room temperature (25°C) for four hours, after which they were photographed with an ultraviolet camera and fluorescent images were obtained after treatment (after being left for four hours). Figure 3 shows the fluorescent images of the subjects after treatment. Liquid Foundation 1 is on the left in Figure 3, and Liquid Foundation 2 is on the right.

[0051] Next, the pre-treatment fluorescent area was calculated from the obtained pre-treatment fluorescent image, and the post-treatment fluorescent area was calculated from the obtained post-treatment (after leaving it for 4 hours) fluorescent image. The fluorescence area reduction rate was calculated using the following formula 2, and the average of the three subjects was calculated, and the degree of makeup loss was evaluated based on the following evaluation criteria. The results are shown in Table 2. [Formula 2] Fluorescence area reduction rate (%) = [(CD) / C] x 100 In Equation 2, C is the fluorescent area before treatment (before being left for 4 hours), and D is the fluorescent area after treatment (after being left for 4 hours).

[0052] [Evaluation criteria] ×: Fluorescence area reduction rate is 80% or more △: Fluorescence area reduction rate is 50% or more but less than 80% ○: Fluorescence area reduction rate is 20% or more but less than 50% ◎: Fluorescence area reduction rate is less than 20%

[0053] [Table 2]

[0054] The results in Table 2, Figures 2 and 3 show that the degree of makeup smudging differs depending on the type of cosmetic, and that Foundation 2 showed a smaller rate of decrease in the fluorescence area than Foundation 1, making it less likely to smudging and more durable. This demonstrates that the evaluation method of the present invention makes it possible to easily and quantitatively evaluate the degree of makeup smearing.

[0055] Example 3 -Evaluation of cleansing properties of cleansing detergents (actual use test by subjects)- A test cosmetic (Liquid Foundation 3) was prepared by mixing 0.5 g of Lumate® (manufactured by Sakai Chemical Industry Co., Ltd.), a fluorescent substance that emits visible light when excited by ultraviolet light, with 99.5 g of liquid foundation (prototype) in a mixer. Three subjects (men and women in their 30s) applied 0.2 g of the test cosmetic (Liquid Foundation 3) to each side of their face. After drying for 10 minutes, images were taken with an ultraviolet camera (VISIA® Evolution, manufactured by Canfield Scientific) to obtain pre-treatment (pre-washing) fluorescent images.

[0056] Next, one pump of each of the cleansers to be evaluated (oil cleansing cleanser 1 (prototype) and oil cleansing cleanser 2 (prototype)) was applied to both sides of the face, and then rinsed off. Fluorescent images were then taken after the treatment (after the cleansing process).

[0057] Next, the pre-treatment fluorescent area was calculated from the obtained pre-treatment (before washing treatment) fluorescent image, and the post-treatment fluorescent area was calculated from the obtained post-treatment (after washing treatment) fluorescent image, and the fluorescent area remaining rate was calculated using the above formula 1. The average of the three people was calculated, and the degree of cleansing ability of the cleanser was evaluated based on the following evaluation criteria. The results are shown in Table 3.

[0058] [Evaluation criteria] ×: Fluorescent area remaining rate is 50% or more △: Fluorescent area remaining rate is 30% or more but less than 50% ○: Fluorescent area remaining rate is 10% or more but less than 30% ◎: Fluorescent area remaining rate is less than 10%

[0059] [Table 3]

[0060] The results in Table 3 show that there are differences in cleansing properties depending on the type of cosmetic product, and that Oil Cleansing Cleanser 2 has a smaller fluorescence area retention rate than Oil Cleansing Cleanser 1, indicating superior cleansing properties. This demonstrates that the evaluation method of the present invention allows the degree of detergency to be evaluated simply and quantitatively.

Claims

1. an application step of applying a fluorescent substance that emits visible light when excited by ultraviolet light to a measurement object to which a cosmetic has been applied, or applying a test cosmetic containing a fluorescent substance that emits visible light when excited by ultraviolet light to the measurement object; a fluorescence image acquisition step of acquiring fluorescence images of the measurement object before and after a predetermined processing using an ultraviolet irradiation photography means for the measurement object before and after the predetermined processing; a comparison step of comparing a pre-treatment fluorescence area calculated from a predetermined pre-treatment fluorescence image with a post-treatment fluorescence area calculated from a predetermined post-treatment fluorescence image; An evaluation method comprising:

2. The evaluation method according to claim 1, wherein the ultraviolet irradiation photographing means is a combination of an ultraviolet irradiator and a visible light camera, a combination of an ultraviolet irradiator and an ultraviolet camera, or an imaging analysis device having an ultraviolet irradiator, an ultraviolet camera, and an image analysis unit.

3. The evaluation method according to claim 1 , wherein the measurement object is artificial skin or the skin of a subject.

4. 2. The evaluation method according to claim 1, wherein the fluorescent substance is at least one selected from the group consisting of a composite oxide containing manganese, a composite oxide containing cerium, and fluorescent zinc oxide.

5. The evaluation method according to claim 1 , wherein the application of the fluorescent substance is performed by spraying a solution containing the fluorescent substance.

6. The evaluation method according to claim 1 , wherein the fluorescent substance is applied by applying a powder containing the fluorescent substance with a cosmetic brush.

7. The evaluation method according to claim 1 , wherein the fluorescent substance is applied by applying a powder containing the fluorescent substance with a cosmetic puff.

8. The evaluation method according to claim 1 , wherein the predetermined treatment is a treatment in which a cosmetic is applied to the measurement object to which the fluorescent substance has been applied, and then the measurement object is washed with a cleanser to be evaluated.

9. The evaluation method according to claim 7, wherein two or more cleansing agents having different compositions are used in combination.

10. The evaluation method according to claim 8 or 9, wherein in the comparison step, a fluorescence area remaining rate is calculated based on the following mathematical formula 1 to evaluate the degree of cleanability. [Formula 1] Fluorescence area remaining rate (%) = (B / A) x 100 In the formula 1, A is the fluorescent area before treatment, and B is the fluorescent area after treatment.

11. 2. The evaluation method according to claim 1, wherein the predetermined treatment is a treatment in which the cosmetic to be evaluated is applied, and then the measurement object to which the fluorescent substance has been applied is left at room temperature for 4 to 6 hours.

12. 2. The evaluation method according to claim 1, wherein the predetermined treatment is a treatment in which the subject, to whom the fluorescent substance has been applied, is asked to wait quietly at room temperature for 4 to 6 hours after applying the cosmetic to be evaluated.

13. The evaluation method according to claim 11 or 12, wherein in the comparison step, a fluorescence area reduction rate is calculated based on the following mathematical formula 2 to evaluate the degree of makeup breakdown: [Formula 2] Fluorescence area reduction rate (%) = [(CD) / C] x 100 In Equation 2, C is the fluorescent area before treatment, and D is the fluorescent area after treatment.

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