Evaluation method for removing sunscreen and application thereof

Abstract

The invention provides an evaluation method for removing sunscreen and application thereof, and the evaluation method comprises the steps: precisely collecting and analyzing skin image parameter values of a subject before and after using a sunscreen product and after cleaning through an image collection and analysis technology; the removal (cleaning) rate is represented by the ratio of the color change value delta E2 of the cleaned skin to the color value delta E1 of the skin coated with the sunscreen, so that the change of the sample before and after cleaning is considered, and the influence of the coated sample and the color of the skin is also considered. The unloading sunscreen evaluation method not only improves the accuracy of data acquisition, but also ensures the accuracy of the evaluation result and the comparability of the performances of different products through specific cleaning rate calculation and sunscreen unloading grade evaluation, and has wide adaptability and practicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of cosmetics, and in particular relates to a sunscreen removal evaluation method and application thereof. Background Art

[0002] With growing awareness of sun protection, the market demand for effective sunscreen removal is growing. While surfactant systems are currently widely used for sunscreen removal, there is a lack of unified standards and methods for evaluating their effectiveness. This deficiency in evaluation limits the accurate assessment and improvement of product performance and is a major pain point in current technologies.

[0003] At present, the evaluation of the effect of removing sunscreen mainly relies on the following methods: First, subjective evaluation by consumers, which judges the effect of makeup removal based on the user's feelings and visual observations. This method is simple and intuitive, but lacks scientificity and consistency. The second is skin model testing, which uses artificial skin or similar models to evaluate the effectiveness of makeup removal products. This method can provide more consistent data, but may not fully reflect the specific performance on real skin. The third is the human testing method. The current human testing method is to use a probe (such as Colorimeter) for testing. This method is more convenient to test, but during the test, the probe will contact and press the skin, which can easily damage the sample that has formed a film in the test area and interfere with subsequent test data.

[0004] Based on some problems existing in the above methods, there is an urgent need for an evaluation method that can scientifically evaluate the effectiveness of surfactant systems in removing sunscreen in actual use environments and ensure the reliability of the test results. Summary of the Invention

[0005] To address the challenges of existing technologies, the present invention provides a novel sunscreen removal evaluation method. By incorporating imaging technology, this method quantitatively analyzes removal results, providing accurate data reflecting the sunscreen removal ability of various surfactant systems. This not only enhances the scientific and objective nature of the evaluation, but also enables simultaneous evaluation of the removal effects of multiple sunscreens, significantly improving efficiency.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a method for evaluating the cleaning effect of a cleaning product on a sunscreen product. The method uses image acquisition combined with IPP software to analyze skin image parameters, and calculates the cleaning rate of the cleaning product based on the skin color change ΔE1 before and after the subject applies the sunscreen, and the skin color change ΔE2 before and after cleaning the sunscreen.

[0008] The present invention introduces image acquisition and analysis technology to accurately measure and analyze skin image parameters, rather than using a probe-based skin colorimeter to collect skin color parameters L*, a*, and b* to evaluate the removal (cleansing) effect of sunscreen products. This is because instruments that require contact with the skin to collect color parameters are not suitable for collecting skin color parameters after sunscreen application. After the sunscreen product is applied to the skin and forms a film, the pressure of the probe during the acquisition process may damage the sunscreen film or cause part of the sunscreen sample to stick to the probe. If the probe is not cleaned properly, it will directly affect subsequent acquisition, resulting in large errors in the L*, a*, and b* values ​​used to calculate the cleaning rate and evaluate the cleaning effect. In contrast, non-contact image acquisition technology can avoid the above problems.

[0009] The image acquisition technology provided by the present invention is to acquire images through VISIA-CR, and to analyze and obtain the skin color parameter values ​​in the image through IPP software. Image acquisition technology is usually used to evaluate the lasting effect of makeup. An image acquisition instrument is used to obtain skin images, and then image analysis software is used for analysis, including but not limited to pore area ratio / spot count / uniformity / skin texture analysis, etc. However, this technology has not yet been applied to the evaluation of the sunscreen removal effect of cleaning products. The present invention uses VISIA-CR acquisition technology to respectively acquire images of the subject's skin at the initial stage, after applying sunscreen, and after cleaning the sunscreen, and uses IPP software to analyze the image parameters. The entire process does not require contact with the skin, which not only improves the accuracy of data acquisition, but also ensures the accuracy of the evaluation results and the comparability of performance between different products through specific cleaning (removal) rate calculation and sunscreen removal level evaluation.

[0010] Furthermore, the calculation formula of the cleaning rate is:

[0011]

[0012] In some embodiments, the experimental results of the present invention demonstrate that compared with the prior art method of using a standard curve to convert the light intensity change rate Δ obtained by image analysis into the amount of skin residue and then derive the cleaning rate, the evaluation results obtained by the skin color parameter processing and cleaning rate calculation formula provided by the present invention are more objective and accurate.

[0013] Furthermore, the skin color parameters include L*, a*, b*,

[0014] described

[0015] described

[0016] Furthermore, the L* T0 、a* T0 、b* T0The initial skin color parameters L*, a*, and b* of the test area of ​​the subject; the L* T1 、a* T1 、b* T1 Skin color parameters L*, a*, b* after applying sunscreen to the test area of ​​the subject; the L* T2 、a* T2 、b* T2 The skin color parameters L*, a*, and b* of the test area after cleaning and sun protection were measured for the subjects.

[0017] After performing parameter analysis on the collected image, the parameters L*, a*, and b* that can characterize the image characteristics are obtained. The color change formula between makeup after a period of time and immediately after makeup is used as a reference. To characterize the color change involved in the present invention, the color change between the test area after applying the sunscreen sample and the original skin state is first calculated as ΔE1 (this evaluation method is applicable to samples with ΔE1>2 after application, that is, there is a visible color difference under ultraviolet light before and after the sunscreen sample is applied to the skin). Then, the color change between the test area after the surfactant system is cleaned and the test area after applying the sunscreen sample is calculated as ΔE2. Under ideal conditions, the skin color parameters after cleansing are equal to the skin color parameters in the original skin state, that is, ΔE1=ΔE2, and the removal (cleaning) rate is 100%; conversely, in a completely uncleaned state, the skin color parameters after cleansing are equal to the skin color parameters after the sample is applied to the skin, that is, ΔE2=0, and the removal (cleaning) rate is 0%. Therefore, the calculation of the removal (cleaning) rate actually depends on the degree of convergence between ΔE2 and ΔE1. ​​The cleaner the cleaning, the closer the removal (cleaning) rate is to 100%, and the less thoroughly cleaned, the closer the removal (cleaning) rate is to 0%. The present invention uses the ratio of ΔE2 to ΔE1 to express the removal (cleaning) rate, which takes into account the changes in the sample before and after cleaning, as well as the influence of the applied sample and the skin color itself.

[0018] In some embodiments, the present invention verifies the accuracy, stability and reliability of the above-mentioned sunscreen removal evaluation method. First, the evaluation results of the cleaning rate and cleaning ability of the same cleaning sample on different sunscreen samples show that the sunscreen removal evaluation method provided by the present invention can effectively distinguish the differences in the removal effect of the same cleaning sample on different sunscreen products. For sunscreen products with the same sunscreen type and SPF value, the cleaning rate obtained by the evaluation method of the present invention is different, indicating that the evaluation method of this patent is sensitive enough to detect subtle differences in the removal effect. Secondly, the results of multiple tests on the same cleaning product and sunscreen product show that the cleaning rate and removal rate evaluation are consistent, indicating that the evaluation method is accurate in determining the skin color parameter value in the cleaning rate calculation and the evaluation results are stable. Finally, compared with the existing image observation method, the evaluation results of the present invention are consistent with the results of the existing method, indicating that the evaluation results of the present invention are accurate, but for sunscreen products with the same SPF value, the cleaning rate evaluation results of the present invention are more accurate and can distinguish subtle differences between products. On the one hand, it improves the accuracy of the sunscreen removal evaluation, and on the other hand, it enhances the practicality and guidance of the evaluation.

[0019] After obtaining the calculation results of the removal (cleaning) rate, it is also necessary to evaluate its removal (cleaning) ability level, which is also lacking in the current sunscreen removal evaluation method. The present invention refers to the distribution of levels of easy / washable / difficult to wash / unwashable with water in the "Evaluation Method for Sunscreen Cosmetics Washable with Water" to evaluate the removal (cleaning) level of sunscreen products by cleaning samples, which are divided into easy to remove, removable, difficult to remove, and unremovable sunscreen. When the cleaning rate of the cleaning sample is ≥90%, it means that the sunscreen is easy to remove; when the cleaning rate of the cleaning sample is ≥75% and <90%, it means that the sunscreen is removable; when the cleaning rate of the cleaning sample is ≥50% and <75%, it means that the sunscreen is difficult to remove; when the cleaning rate of the cleaning sample is <50%, it means that the sunscreen is not removable. In addition, the present invention also provides a reference map according to different removal (cleaning) ability levels, which can be used as an intuitive reference for the evaluation results.

[0020] Furthermore, the method comprises the following steps:

[0021] S1: Use image acquisition technology to collect the initial skin color parameters L* of the test area of ​​the subject T0 、a* T0 、b* T0 ;

[0022] S2: Apply the sunscreen sample to the test area of ​​the subject's skin and collect the skin color parameter L* of the test area after applying the sunscreen in the same way as S1. T1 、a* T1 、b* T1 ;

[0023] S3: Clean the test area with a clean sample and collect the skin color parameter L* of the test area after the clean sample is used in the same way as S1. T2 、a* T2 、b* T2 .

[0024] S4: Calculate the cleaning rate of the cleaned sample according to the formula as an indicator for evaluating the cleaning effect of the cleaning product on the sunscreen product.

[0025] Furthermore, the application amount of the sunscreen sample is 1-5 mg / cm 2 The smear amount of the cleaning sample is 38-55 mg / cm 2 .

[0026] The cleaning samples applicable to this evaluation method can be any surfactant system cleaning products with cleaning ability, including but not limited to cleansing foam, cleansing cream, shower gel, shower oil, etc.; the sunscreen products applicable to this evaluation method can be any beauty and skin care products containing sunscreen or having sun protection and anti-ultraviolet function, including but not limited to sunscreen cream, sunscreen lotion, bare face cream, etc.

[0027] On the other hand, the present invention provides an application of an image acquisition method for evaluating the cleaning effect of a cleaning product on a sunscreen product. The image acquisition method includes using VISIA-CR image acquisition technology to acquire a skin color image of a subject, and calculating the cleaning rate of the cleaning product based on the skin color change ΔE1 before and after the subject applies sunscreen, and the skin color change ΔE2 before and after cleaning the sunscreen.

[0028] Furthermore, the calculation formula of the cleaning rate is:

[0029]

[0030] Furthermore, the skin color parameters include L*, a*, b*,

[0031] described

[0032] described

[0033] The present invention has the following beneficial effects:

[0034] 1. The present invention uses image acquisition and analysis technology to accurately measure and analyze skin image parameters (L*, a*, b*) before, after, and after using sunscreen products, thereby improving the accuracy of data acquisition. The evaluation results are more accurate than traditional evaluation methods, providing a more precise method for evaluating the removal effect, realizing the simultaneous evaluation of the removal effects of multiple sunscreens, and improving efficiency.

[0035] 2. The cleaning rate calculation method and sunscreen removal level assessment proposed in this invention not only allow the removal effect to be accurately measured, but also allow direct comparison between different products, thereby enhancing the practicality and guidance of the assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a reference chart for the evaluation level of cleaning (removal) of sunscreen in Example 1, where A indicates that the sunscreen is easy to remove, with a cleaning rate ≥90%; B indicates that the sunscreen is removable, with a cleaning rate ≥75% and <90%; C indicates that the sunscreen is difficult to remove, with a cleaning rate ≥50% and <75%; and D indicates that the sunscreen cannot be removed, with a cleaning rate <50%.

[0037] Figure 2 This is the skin color spectrum of the subjects in Group A in Example 2 before, after and after using the sunscreen product.

[0038] Figure 3 This is the skin color spectrum of the subjects in Group B in Example 2 before, after and after using the sunscreen product.

[0039] Figure 4 This is the skin color spectrum of the subjects in Group C in Example 2 before, after and after using the sunscreen product.

[0040] Figure 5 This is the skin color spectrum of the subjects in Group D in Example 2 before, after and after using the sunscreen product.

[0041] Figure 6 This is the skin color spectrum of Group 1 subjects in Example 4 before, after and after using the sunscreen product.

[0042] Figure 7 This is the skin color spectrum of Group 2 subjects in Example 4 before, after and after using the sunscreen product. DETAILED DESCRIPTION

[0043] The present invention will be described in further detail below in conjunction with the accompanying drawings and Examples. It should be noted that the following examples are intended to facilitate understanding of the present invention and do not serve to limit the present invention in any way. The reagents used in this example are all known products and were obtained by purchasing commercially available products.

[0044] Example 1: Evaluation method for removing sunscreen provided by the present invention

[0045] The specific implementation steps of the sunscreen removal evaluation method provided by the present invention are as follows:

[0046] (1) Collection of basic skin parameters

[0047] 30 subjects with no tattoos, cuts, scratches, abrasions or scars on the inner forearms were recruited, and the experiment was explained to the subjects, and the subjects signed an informed consent form; first rinse the arm with clean water, and use a lint-free paper towel to dry the moisture of the test area. Then keep the test area exposed and stabilize it in a constant temperature and humidity laboratory (20-22℃, relative humidity 40%-60%) for 20 minutes. Mark the test area with a skin safety pen on the test area of ​​the subject, use VISIA-CR to collect images of the test area, and use IPP software to analyze the skin color parameters L*, a*, b* of the image, and record it as L* T0 、a* T0 、b* T0 .

[0048] (2) Sunscreen sample application and skin parameter collection

[0049] The sunscreen samples were pressurized at 2mg / cm 2 Apply evenly to the test area, wait for the sunscreen sample to form a film on the skin surface, and then collect the skin color parameters of the test area after applying the sunscreen in the same way as above, and record it as L* T1 、a* T1 、b* T1 .

[0050] (3) Clean the sample, remove the sunscreen and collect skin parameters

[0051] Wet the test area with a small amount of water and press the clean sample at 38-55 mg / cm 2 Apply to the test area, massage 40 times at a constant speed to clean the test area, rinse with clean water (1L of clean water), and then dry with a lint-free tissue. After the skin stabilizes for 5 minutes, collect the skin color parameter L* of the test area after removing the sunscreen in the same way as above T2 、a* T2 、b* T2 .

[0052] (4) Cleaning (removal) rate evaluation

[0053] First, the cleaning (removal) rate of the cleaning sample on the sunscreen sample in the test area is calculated according to the cleaning (removal) rate calculation formula. According to the evaluation indicators in Table 1, it is determined whether the cleaning sample has the ability to easily remove, remove, difficult to remove, or non-removable the specified sunscreen sample.

[0054] The calculation formula for the cleaning (removal) rate is as follows:

[0055] After application

[0056] After cleaning

[0057]

[0058] Table 1 Cleaning (removal) sunscreen evaluation index

[0059]

[0060]

[0061] Example 2

[0062] This example investigates the sunscreen removal evaluation method provided by the present invention for evaluating the removal efficiency of different sunscreen systems from the same cleansing sample. The specific implementation method is essentially the same as in Example 1, wherein the types of sunscreen samples are shown in Table 2, and the composition of the cleansing sample includes: amino acid surfactant: 10-15%, APG surfactant: 8-10%, and nonionic surfactant: 1-5%. The evaluation results are shown in Table 2, and the reference spectrum of the AD group is shown in Table 2. Figure 2-Figure 6 .

[0063] Table 2 Cleaning evaluation results of cleaning samples on different sunscreen samples

[0064] Group Sunscreen type Sun Protection Factor (SPF) Cleaning (removal) rate% Cleaning (removal) ability A Pure physical water-in-oil 50 39.71 Non-removable B Oil-in-water pure physics 20 99.76 Easy to remove C Pure physical water-in-oil 30 55.11 Difficult to remove D Pure physical water-in-oil 30 61.41 Difficult to remove

[0065] Comparing Group A and Group B, the data in Table 2 shows that Group A, which used a water-in-oil pure physical sunscreen with an SPF of 50, had a cleaning rate of 39.71%, resulting in an "unremovable" rating. In contrast, Group B, which used an oil-in-water pure physical sunscreen with an SPF of 20, had a cleaning rate of 99.76%, resulting in an "easy to remove" rating. This demonstrates that the method of the present invention can accurately identify differences in removal difficulty due to differences in sunscreen type and SPF value.

[0066] Comparing Groups C and D, we can see that while both use a water-in-oil, pure physical sunscreen with an SPF of 30, the cleaning rates calculated using the method provided by this invention are 55.11% and 61.41%, respectively, both being rated as "difficult to remove." Despite using the same sunscreen type and SPF, the difference in cleaning rates demonstrates that the evaluation method provided by this invention is sensitive enough to detect subtle differences in removal effectiveness.

[0067] The results from all groups demonstrate that the proposed evaluation method not only accurately assesses the removal efficacy of each sunscreen product but also effectively distinguishes differences in the removal ability of the same cleanser sample against different sunscreen products. This precise assessment is crucial for optimizing cleanser formulations and guiding consumers in selecting appropriate products. It also provides scientific and objective data support for evaluating the sunscreen removal efficacy of cleanser samples.

[0068] Example 3

[0069] This example examines the sunscreen removal evaluation method provided by the present invention, comparing two evaluation results using the same commercially available cleaning product to evaluate the cleaning efficiency of the same commercially available sunscreen. The specific testing method and cleaning efficiency calculation were the same as in Example 1. The commercially available cleaning products and sunscreen products are shown in Table 3, along with the evaluation results.

[0070] Table 3 Results of two cleaning evaluations of commercial cleaning products versus commercial sunscreen products

[0071]

[0072] As can be seen from the data in the table above, the cleaning effect of the same commercially available cleaning product on the same commercially available sunscreen product was evaluated twice using the evaluation method provided by the present invention. The difference in the cleaning (removal) rate between the two tests ranged from 0.22 to 0.60. For the same cleaning product and sunscreen combination, the two tests showed completely consistent removal ability evaluations, such as "difficult to remove" or "removable." This demonstrates that the method provided by the present invention provides stable evaluation results for multiple tests of the same combination, and provides accurate and consistent criteria for determining the removal (cleaning) level.

[0073] Example 4

[0074] In order to verify that the evaluation method provided by the present invention is accurate in evaluating the removal effect of sunscreen products, this example first compares the sunscreen removal evaluation method of the present invention with the existing picture observation method, and studies the removal effect of a commercially available cleaning product (Hansu Oil Control and Acne Cleansing Cream) on a commercially available sunscreen (Hansu Whitening and Spot Lightening Sunscreen Milk) (Group 1), and the removal effect of a commercially available cleaning product (Red Elephant Green Sweet Pure Oil Control Double Tube Cleanser) on a commercially available sunscreen (Red Elephant Green Sweet Clear and Transparent Protection Sunscreen Milk) (Group 2). The evaluation methods for the two groups of removal effects adopt the following two methods:

[0075] 1. The test method of the skin test area, the collection of skin color parameters, and the calculation and evaluation of the cleaning rate are the same as in Example 1.

[0076] Second, the testing method for the skin test area was the same as in Example 1. The skin image acquisition method referred to the "A Method for Evaluating the Cleansing Power of Cleansing Cosmetics" was used to capture images of each test area using a microscope. The images were then observed to determine if the skin texture was clear and the grooves between the skin were clean. If there was no product residue on the skin surface and between the grooves after cleansing, the sunscreen was completely removed, with a cleaning rate of 90-100%. If there was a small amount of product residue on the skin surface and between the grooves after cleansing, the sunscreen was removed with a cleaning rate of between 75-90%. If the product remained on the skin surface after cleansing and filled the grooves between the skin texture, the sunscreen was difficult or impossible to remove, with a cleaning rate of less than 75%.

[0077] 30 volunteers were randomly invited to compare the evaluation results of methods one and two to evaluate the advantages of the sunscreen removal evaluation method provided by the present invention compared with the existing evaluation methods.

[0078] Table 4 Comparison of the results of the two evaluation methods

[0079]

[0080] In this embodiment, 30 randomly invited volunteers compared the evaluation results of method one with the image collection of method two. 100% of the observers believed that the cleaning rate and cleaning ability obtained by method one were consistent with the cleanliness observed in the pictures collected by method two, indicating that the evaluation method provided by the present invention and the evaluation results of the existing image observation method are highly consistent and the evaluation results are accurate. However, according to the test results, it can be seen that the present invention is more accurate in evaluating the two cleansers. For the Hanshu Whitening and Spot-Lightening Sunscreen Lotion with a sun protection index of 50, the cleaning rate after using the Hanshu Oil Control and Acne Cleansing Cream is 80.45%; for the Hanshu Red Elephant Green Sweet Clear and Transparent Sunscreen Lotion with a sun protection index of 50, the cleaning rate after using the Red Elephant Green Sweet Clear and Oil Control Double-Tube Cleansing Lotion is 86.57%, indicating that the two cleansers have good removal ability for sunscreen products with high SPF values ​​and can effectively remove most of the sunscreen residues; in addition, according to the evaluation indicators provided in Example 1, the cleaning effects of the two cleansers can be evaluated as "removable", which means that after using these two cleansers, the residual sunscreen ingredients on the skin have been reduced to an acceptable level, which will not cause a significant burden on skin health, and also ensure the effectiveness of subsequent skin care steps. The existing evaluation method can only derive an approximate cleaning effect and a wide range of cleaning rates, and cannot accurately evaluate the specific removal effect of a cleanser on sunscreen. The above results show that the sunscreen removal evaluation method provided by the present invention significantly improves the accuracy of sunscreen removal evaluation and has significant practical advantages. It can accurately evaluate the performance of commercially available products under actual usage conditions. It not only demonstrates the value of this method in practical applications, but also provides consumers and brands with a reliable performance evaluation tool.

[0081] This example then further compares the UV image acquisition and analysis method described in patent document CN106370604B with the sunscreen removal evaluation method of the present invention. The specific operation is as follows:

[0082] The subject's skin was cleaned and stabilized according to the method of Example 1. Five test areas of equal size were marked on the subject's test area with a skin safety pen. 2 mg / cm2 of the sunscreen sample was evenly applied to each test area. 2The calculation is that the amount of sunscreen sample applied to test area 1 is 100%, the amount of sunscreen sample applied to test area 2 is 75%, the amount of sunscreen sample applied to test area 3 is 25%, the amount of sunscreen sample applied to test area 4 is 25%, and the amount of sunscreen sample applied to test area 5 is 0%. No cleaning product is used to remove the sunscreen from the five test areas. The skin color parameters and average light intensity of test area 1 before and after applying the sunscreen, as well as the skin color parameters and average light intensity of test areas 2-5 after applying the sunscreen, are collected according to the methods of Example 1 of the present invention and the embodiments of patent document CN106370604B. The removal rate is calculated according to the formulas in the corresponding methods.

[0083] The values ​​collected after sunscreen application on test areas 1-5 were used as the values ​​for five different cleaning effects. Under ideal conditions, the cleaning rate for test area 1 is 0%, the cleaning rate for test area 2 is 25%, the cleaning rate for test area 3 is 50%, the cleaning rate for test area 4 is 75%, and the cleaning rate for test area 5 is 100%. The actual cleaning rates obtained by the two methods for the five test areas are shown in Table 5.

[0084] Table 5 Comparison of cleaning rates of the two evaluation methods

[0085] Test Area The present invention UV image analysis 1 0％ 1.28％ 2 24.98％ 27.19％ 3 50.08％ 45.55％ 4 74.97％ 79.68％ 5 100％ 100％

[0086] The results in Table 5 show that the cleaning rate calculated using the sunscreen removal evaluation method provided by the present invention is nearly identical to that obtained under ideal conditions, demonstrating that the image acquisition method provided by the present invention accurately measures skin color parameters, and the cleaning rate calculated using the formula is more accurate, resulting in a more scientific and precise evaluation. However, the cleaning rate calculated using the average light intensity of the UV image in the comparative method exhibits significant deviations from the ideal, with large fluctuations. This indicates that the method of calculating the cleaning rate using a fitted standard curve after measuring and analyzing the average light intensity of the UV image is still inaccurate, and that this method still has certain drawbacks in evaluating the effectiveness of sunscreen removal. In comparison, the method provided by the present invention offers greater accuracy and stability, offering significant advantages.

[0087] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for evaluating the cleaning effect of a cleaning product on a sunscreen product, characterized in that: The method uses image acquisition combined with IPP software to analyze skin image parameters, and calculates the cleaning rate of the cleaning product based on the skin color change ΔE1 before and after applying sunscreen and the skin color change ΔE2 before and after cleaning the sunscreen.

2. The method according to claim 1, wherein The calculation formula of the cleaning rate is:

3. The method according to claim 2, wherein The skin color parameters include L*, a*, b*, described 4. The method according to claim 3, wherein The L* T0 、a* T0 、b* T0 The initial skin color parameters L*, a*, and b* of the test area of ​​the subject; the L* T1 、a* T1 、b* T1 Skin color parameters L*, a*, b* after applying sunscreen to the test area of ​​the subject; the L* T2 、a* T2 、b* T2 The skin color parameters L*, a*, and b* of the test area after cleaning and sun protection were measured for the subjects.

5. The method according to claim 4, wherein The following steps are involved: S1: Use image acquisition technology to collect the initial skin color parameters L* of the test area of ​​the subject T0 、a* T0 、b* T0 ; S2: Apply the sunscreen sample to the test area of ​​the subject's skin and collect the skin color parameter L* of the test area after applying the sunscreen in the same way as S1. T1 、a* T1 、b* T1 ; S3: Clean the test area with a clean sample and collect the skin color parameter L* of the test area after the clean sample is used in the same way as S1. T2 、a* T2 、b* T2 . S4: Calculate the cleaning rate of the cleaned sample according to the formula as an indicator for evaluating the cleaning effect of the cleaning product on the sunscreen product.

6. The method according to claim 5, wherein The application amount of the sunscreen sample is 1-5 mg / cm 2 .

7. The method according to claim 6, wherein The amount of the clean sample applied is 38-55 mg / cm 2 .

8. Application of image acquisition method in evaluating the cleaning effect of cleaning products on sunscreen products, characterized in that: The image acquisition method includes using VISIA-CR image acquisition technology to acquire skin color images of subjects, and calculating the cleaning rate of the cleaning product based on the skin color change ΔE1 before and after the subjects apply the sunscreen, and the skin color change ΔE2 before and after cleaning the sunscreen.

9. The use according to claim 8, characterized in that The calculation formula of the cleaning rate is:

10. The use according to claim 9, characterized in that The skin color parameters include L*, a*, b*, described

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