Method for testing film forming effect of sunscreen product

Abstract

The invention provides a method for testing the film forming effect of a sunscreen product. The method comprises the following steps: cleaning a to-be-tested area of a subject, and standing still for at least 30 minutes in a constant-temperature and constant-humidity environment; obtaining a comparison image through a face spectral imager; smearing an influence medium and a test sample on the to-be-tested area; and obtaining a test image through a face spectral imager, and determining the film forming effect of the test sample through the comparison image and the test image. Through the test method provided by the invention, the market blank is filled, the film forming effect of the sunscreen product can be detected, and the requirements of customers with the detection requirements are met. Meanwhile, a human face imaging effect verification method is adopted, so that the method has the advantages of excellent repeatability and reproducibility, simplicity and convenience in operation, high speed, easiness in obtaining used equipment and high generalizability.

Description

Technical Field

[0001] This application relates to the field of cosmetic testing technology, and in particular to a testing method for the film-forming effect of sunscreen products. Background Technology

[0002] A good sunscreen product needs excellent film-forming properties; a film-forming agent is an indispensable element for achieving outstanding sun protection. Choosing the right film-forming agent is crucial in the development of sunscreen products. The film-forming property of a sunscreen product refers to its ability to form a continuous, uniform, stable, and flexible film on the skin after application, as the solvent evaporates. This film-forming property is an important indicator of a sunscreen product's sun protection performance.

[0003] The benefits of good film-forming properties include: after film formation, sunscreen agents can be evenly dispersed on the skin surface, effectively avoiding aggregation or pores, thus providing comprehensive UV protection and improving SPF and PA values; a high-quality film layer has excellent adhesion to the skin, resisting sweat, moisture, and friction, ensuring the longevity of sun protection effects, while also enhancing the product's water resistance and abrasion resistance; film-forming properties directly affect the final skin feel of the product. A good film layer provides a light, breathable, non-sticky, and non-tightening comfortable feel, effectively filling skin texture, improving the dispersion of raw materials, presenting a more natural appearance, and avoiding whitening or shine; film-forming properties not only optimize sun protection effects but also protect the skin barrier by reducing transepidermal water loss (TEWL), further enhancing the overall efficacy of the product. However, current technologies lack relevant testing standards for film-forming effects. Summary of the Invention

[0004] In view of the aforementioned problems, this application is made to provide a test method for the film-forming effect of sunscreen products that overcomes or at least partially solves the aforementioned problems.

[0005] This invention discloses a method for testing the film-forming effect of sunscreen products, including the following steps:

[0006] The test area of ​​the subject was cleaned and the subject sat quietly in a constant temperature and humidity environment for at least 30 minutes.

[0007] Acquire contrast images using a facial spectral imager;

[0008] Apply the influencing medium and the test sample to the area to be tested;

[0009] Test images are acquired using a facial spectral imager, and the film-forming effect of the test sample is determined by comparing the comparison images with the test images.

[0010] Further, the step of acquiring a test image by the facial spectral imaging instrument and determining the film forming effect level of the test sample by comparing the contrast image with the test image comprises:

[0011] The parameter change value of the contrast image and the test image is verified for normal distribution.

[0012] If it is normal distribution, paired sample test is performed on the contrast image and the test image to obtain a test result; or, if it is non-normal distribution, sign rank test is performed on the contrast image and the test image to obtain a test result.

[0013] The film forming effect is determined according to the test result.

[0014] Further, before the step of verifying the parameter change value of the contrast image and the test image for normal distribution, the method further comprises:

[0015] The contrast parameters are acquired according to the contrast image, wherein the contrast parameters comprise contrast skin uniformity, contrast brightness value, contrast whiteness value and contrast pore area ratio;

[0016] The test parameters are acquired according to the test image, wherein the test parameters comprise test skin uniformity, test brightness value, test whiteness value and test pore area ratio.

[0017] Further, when the sign rank test is performed on the contrast image and the test image, the significance difference level is 0.05.

[0018] Further, when the step of verifying the parameter change value of the contrast image and the test image for normal distribution, if the significance value is greater than 0.05, it is normal distribution; if the significance value is less than or equal to 0.05, it is non-normal distribution.

[0019] Further, the influencing medium is a guest-supplied cosmetic.

[0020] Further, the guest-supplied cosmetic is subjected to safety test and influence test.

[0021] Further, the test area is the face; the contrast image comprises a contrast front image, a contrast left image and a contrast right image; the test image comprises a test front image, a test left image and a test right image.

[0022] Further, in the step of cleaning the test area of the subject, the test area is cleaned by a non-irritating cleansing product, and after cleaning, the water is absorbed by a clean disposable towel or non-dusting paper.

[0023] Further, when applying the influence medium and the test sample, the same application force and method are adopted, and the test sample is applied uniformly at an amount of 0.02-0.03g per square centimeter, and after application, 8s is waited before acquiring the test image.

[0024] The present application has the following advantages:

[0025] In the embodiments of the present application, in order to solve the problem that there is no method for detecting the film forming effect of sunscreen products in the prior art, the present application provides a test method for the film forming effect of sunscreen products, comprising the steps of: washing the test area of a subject and sitting still in a constant temperature and humidity environment for at least 30min; acquiring a contrast image by a facial spectral imaging instrument; applying an influence medium and a test sample to the test area; acquiring a test image by the facial spectral imaging instrument, and determining the film forming effect of the test sample by the contrast image and the test image. The test method provided by the present application fills the market gap, can detect the film forming effect of sunscreen products, and meets the requirements of customers who have such detection needs. At the same time, the human facial imaging efficacy verification method has excellent repeatability and reproducibility, is simple to operate, fast, and the equipment used is easy to obtain, and is extremely popular. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the description of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0027] Figure 1 is a step flow chart of a test method for the film forming effect of sunscreen products provided by an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0029] The inventors found through analysis of the prior art that in the development process of sunscreen products, it is crucial to select a suitable film forming agent. The film forming property of sunscreen products is the ability of a product to form a continuous, uniform, stable and flexible film on the skin after being applied on the skin with the volatilization of the solvent, and the film forming property of sunscreen products is an important indicator for measuring the sunscreen performance of the product. However, there is no related technical solution to detect the film forming effect.

[0030] In the embodiments of the present application, in order to solve the problem that there is no method for detecting the film forming effect of sunscreen products in the prior art, the present application provides a test method for the film forming effect of sunscreen products, comprising the steps of: cleaning the test area of a subject and sitting in a constant temperature and humidity environment for at least 30 minutes; obtaining a contrast image by a facial spectral imager; applying an influence medium and a test sample to the test area; obtaining a test image by the facial spectral imager, and determining the film forming effect of the test sample by the contrast image and the test image. The test method provided by the present application fills the market gap, can detect the film forming effect of sunscreen products, and meets the requirements of customers who have such detection needs. At the same time, the human face imaging efficacy verification method has excellent repeatability and reproducibility, is simple to operate, fast, and the equipment used is easy to obtain, and is extremely popular.

[0031] Reference Figure 1 , a test method for the film forming effect of sunscreen products is shown, comprising the steps of:

[0032] S110, cleaning the test area of a subject and sitting in a constant temperature and humidity environment for at least 30 minutes;

[0033] S120, obtaining a contrast image by a facial spectral imager;

[0034] S130, applying an influence medium and a test sample to the test area;

[0035] S140, obtaining a test image by the facial spectral imager, and determining the film forming effect of the test sample by the contrast image and the test image.

[0036] It should be noted that first, the test area of the subject is cleaned, and the purpose of this step is to remove interfering substances such as dirt, grease, and residual skincare products on the surface of the test area, and to ensure the initial consistency of the test environment. After cleaning, the subject is required to sit in a constant temperature and humidity environment for at least 30 minutes, which is to stabilize the skin state - fluctuations in temperature and humidity can affect the physiological state of the skin (such as oil secretion and moisture content), and sitting for a sufficient time can reduce the immediate impact of external factors on the skin, ensuring that the initial state data obtained later is more reliable.

[0037] A contrast image (i.e. a skin image before applying the product) of the test area is taken by a facial spectral imager. The facial spectral imager can capture the characteristics of the skin under different spectra, and compared with ordinary cameras, it can obtain more detailed skin parameters (such as skin color, pore state, uniformity, etc.), providing quantitative basis for subsequent comparison.

[0038] The influence medium is applied to the area to be tested first, and then the sunscreen product to be tested is applied. The influence medium is other skin care products that may be used before the sunscreen product in the daily use scenario, so that the test is closer to the actual use situation, and the film forming effect of the sunscreen product under the influence of other media is tested.

[0039] After application, the test image (i.e., the skin image after the product is applied) is captured again using the facial spectral imager. By comparing the differences between the contrast image and the test image, the film forming effect of the sunscreen product is determined. A good film forming sunscreen product usually forms a uniform covering layer on the skin surface, which may be manifested as an improvement in skin uniformity, a change in the area ratio of pores covered, a change in brightness / whiteness, etc. These changes can be captured and quantitatively analyzed by the spectral imager.

[0040] In the following, the test method for the film forming effect of a sunscreen product in the present exemplary embodiment will be further described.

[0041] In an embodiment of the present application, the step of acquiring the test image by the facial spectral imager and determining the film forming effect grade of the test sample by the contrast image and the test image comprises:

[0042] The parameter change value of the contrast image and the test image is verified for normal distribution;

[0043] If it is normal distribution, paired sample test is performed on the contrast image and the test image to obtain a test result; or, if it is non-normal distribution, sign rank test is performed on the contrast image and the test image to obtain a test result;

[0044] The film forming effect is determined according to the test result.

[0045] It should be noted that if the change value is normally distributed, paired sample test (such as paired t-test) is used. This method is suitable for the mean difference test of paired samples (the same area before and after application on the same subject), and can determine whether the parameter change is caused by the film forming effect.

[0046] If the change value is not normally distributed, sign rank test (a non-parametric test method) is used. When the data does not meet the normal distribution, non-parametric test can avoid errors caused by the non-fulfillment of distribution assumption, and is also used to determine the significance of parameter change.

[0047] If the test result shows that the parameter change has significance, it means that the film forming effect of the sunscreen product is obvious; if the change has no significance, it means that the film forming effect is weak or no effective film is formed.

[0048] As an example, the data variation values of each parameter are subjected to normal distribution test using SPSS statistical software. If Sig. (two-sided) > 0.05, the data is normally distributed, and a paired sample t test is performed. If Sig. (two-sided) < 0.05, the data is not normally distributed, and a Wilcoxon signed rank test is performed. The significance difference level a is 0.05.

[0049] In an embodiment of the present application, before the step of verifying the normal distribution of the parameter variation values of the contrast image and the test image, the method further comprises:

[0050] Obtaining a contrast parameter according to the contrast image, wherein the contrast parameter comprises a contrast skin uniformity, a contrast brightness value, a contrast whiteness value, and a contrast pore area ratio;

[0051] Obtaining a test parameter according to the test image, wherein the test parameter comprises a test skin uniformity, a test brightness value, a test whiteness value, and a test pore area ratio.

[0052] It should be noted that, before the influence medium and the test sample are applied, the skin inherent characteristic parameters extracted from the contrast image include:

[0053] The contrast skin uniformity reflects the original smoothness and consistency of the skin surface (such as whether the skin color is uneven, the texture difference, etc.);

[0054] The contrast brightness value reflects the original light intensity of the skin, and represents the glossiness base of the skin;

[0055] The contrast whiteness value reflects the original whiteness degree or color level reference of the skin;

[0056] The contrast pore area ratio reflects the proportion of the total area of the exposed pores of the skin to the total area of the test region, and represents the visibility base of the pores.

[0057] After the influence medium and the test sample are applied, the skin characteristic parameters extracted from the test image correspond to the contrast parameters one by one, and include:

[0058] The test skin uniformity reflects the smoothness and consistency of the skin surface after the application (good film formation can improve the uniformity and reduce the original texture or color block difference);

[0059] The test brightness value reflects the light intensity of the skin after the application (the thin film may change the light reflection, resulting in brightness change);

[0060] The test whiteness value reflects the whiteness degree of the skin after the application (the coverage or refraction of the thin film may affect the whiteness);

[0061] The test pore area ratio reflects the visible area ratio of the pores after the application (good film formation can cover part of the pores, reducing the ratio).

[0062] In an embodiment of the present application, the significance level of the significant difference is 0.05 when the sign rank test is performed on the contrast image and the test image.

[0063] It should be noted that the significance level (a) is a critical value in statistics for determining whether the difference is statistically significant, representing the risk probability of mistakenly considering that there is a difference. a = 0.05 means that in the sign rank test, when the calculated P value (probability value) is less than 0.05, it is considered that there is a statistically significant difference between the change values of the contrast parameters and the test parameters (i.e. the possibility that the difference is caused by the film forming effect of the sunscreen product is very high, rather than a random error); otherwise, if the P value is greater than 0.05, it is considered that the difference is not significant (may be caused by random factors).

[0064] In an embodiment of the present application, when the significance value is greater than 0.05, the step of verifying the parameter change values of the contrast image and the test image is normally distributed; when the significance value is less than or equal to 0.05, it is not normally distributed.

[0065] It should be noted that the normal distribution verification (such as the commonly used Shapiro-Wilk test, Kolmogorov-Smirnov test, etc.) is a method in statistics for determining whether the data conforms to the normal distribution characteristics, and the significance value (P value) output reflects the probability that the assumption that the data conforms to the normal distribution is established.

[0066] By setting 0.05 as the critical value, the determination threshold of the data distribution type is determined: when P > 0.05, the hypothesis that the data conforms to the normal distribution is supported; when P ≤ 0.05, the hypothesis is rejected and it is determined to be not normally distributed. The threshold of 0.05 balances the risk of misjudgment: when P > 0.05, the probability of mistakenly considering that the data conforms to the normal distribution is low (less than 5%), and the hypothesis can be accepted; when P ≤ 0.05, the possibility that the data does not conform to the normal distribution is higher, and the original hypothesis needs to be rejected.

[0067] In an embodiment of the present application, the influence medium is a guest cosmetic product.

[0068] It should be noted that the influence medium is other cosmetic products that act on the skin together with the test sample (sunscreen product) before or at the same time, and its role is to simulate the situation in which the sunscreen product may be used together with other cosmetic products (such as skin care products, makeup, etc.) in the actual use scenario, so as to evaluate the film forming effect of the sunscreen product in this scenario.

[0069] Using a guest cosmetic product as the influence medium is provided by the customer rather than a general product selected by the test party, which enhances the regularity of the test effect.

[0070] In an embodiment of the present application, the guest cosmetic product is subjected to safety testing and influence testing.

[0071] It should be noted that the safety testing is performed by testing the safety of the skin when the guest cosmetic product and the sunscreen product are used together, so as to avoid skin adverse reactions caused by ingredient interaction or stacking irritation.

[0072] Through an in vitro model (such as a 3D skin model) or a human patch test, it is evaluated whether the skin care product and the sunscreen product mixed / stacked together produce synergistic irritation (such as chemical reaction between ingredients to generate irritating substances, or high-concentration active ingredients stacked together to cause skin barrier damage). For example, a skin care product containing high-concentration acid (such as apricot kernel acid) and a sunscreen product containing alcohol stacked together may increase the risk of skin irritation, which needs to be tested for safety. It is analyzed whether there is a contraindication between the ingredients of the skin care product and the sunscreen product (such as whether the reducing ingredients in the skin care product and the oxidizing ingredients in the sunscreen product react to cause inactivation of the ingredients or generate harmful substances). For example, a skin care product containing vitamin C and a sunscreen product containing oxybenzone stacked together may reduce the efficacy of both due to redox reaction, and it is also necessary to confirm whether a sensitizing intermediate product is generated.

[0073] The influence testing is the influence of the guest cosmetic product on the core function of the sunscreen product, to ensure that the sunscreen product can still stably function after being used together. The influence of the texture of the skin care product (such as an oil-rich cream or a light serum) on the film-forming uniformity and adhesion of the sunscreen product is observed. For example, a skin care product containing a large amount of silicon ingredients may form an isolation film on the skin surface, resulting in uneven adhesion of the sunscreen product and forming film gaps; and a skin care product containing a humectant (such as hyaluronic acid) may increase the humidity of the skin surface layer, affecting the drying speed and tightness of the sunscreen film. Through accelerated experiments (such as high temperature and light conditions), it is tested whether the residual ingredients of the skin care product accelerate the decomposition of the sunscreen (such as whether the oil in the skin care product promotes the oxidation of the chemical sunscreen), or affect the water resistance and sweat resistance of the sunscreen film (such as whether the water-soluble ingredients in the skin care product reduce the water resistance of the sunscreen film). Through in vitro spectroscopy or actual measurement on the human body, the change in the sunscreen index after the sunscreen product is used alone or stacked with the skin care product is compared, to confirm whether the skin care product causes a decrease in sunscreen power due to ingredient adsorption or dilution of the sunscreen.

[0074] In an embodiment of the present application, the test area is the face; the comparison images include a comparison front image, a comparison left image, and a comparison right image; and the test images include a test front image, a test left image, and a test right image.

[0075] It should be noted that the test area is limited to the face because the face is the main and sensitive area for the use of sunscreen products and skin care products together, and the skin of the face has particularity, such as a high density of sebaceous glands, the highest frequency of exposure to sunlight, and a thinner skin barrier than other parts of the body, and the state of the skin directly affects the authenticity and reference value of the test results.

[0076] Contrast front view: A frontal view taken directly facing the tester's face, covering the central areas such as forehead, nose bridge, cheeks, chin, etc., reflecting the overall state of the face (such as skin color, glossiness, redness, etc.).

[0077] Contrast left side view: A side view taken at a 45° angle from the left side of the tester, focusing on covering areas such as the left cheek, left brow, left jawline, etc., capturing the skin texture and sunscreen film adhesion state on the side of the face.

[0078] Contrast right side view: A side view taken at a 45° angle from the right side of the tester, symmetrical to the left side view, covering areas such as the right cheek, right brow, right jawline, etc., ensuring that the state of both sides of the face is recorded.

[0079] Test front view: The same angle and light conditions as the contrast front view, used to compare the overall changes of the face (such as whether there is whitening, makeup removal, redness, etc.).

[0080] Test left side view, test right side view: The same angle as the contrast left side view, right side view, used to compare the detailed changes on the side of the face (such as whether the sunscreen film dissolves due to oil on the side of the face, whether the sunscreen accumulates due to sweating on the brow).

[0081] In an embodiment of the present application, in the step of cleaning the test area of the subject, the cleaning is performed by a non-irritating cleansing product, and after cleaning, the water is absorbed with a clean disposable towel or non-shedding paper.

[0082] It should be noted that through the standardized cleaning process, the original interference factors such as oil, dirt, and residual skincare products on the test area of the subject can be maximally eliminated, so that the skin of all subjects is in a relatively consistent initial state at the beginning of the test, ensuring the objectivity of the subsequent comparison images, such as avoiding the difference between the sunscreen film of a subject with more residual oil and others, affecting the comparability of the results.

[0083] Ensure the accuracy of the film forming effect evaluation: impurities or water residue on the skin surface will directly affect the film forming process of sunscreen products, such as excessive water which may dilute the concentration of sunscreen, and impurities which may cause uneven film formation. Standardizing the cleaning and drying steps can ensure that the sunscreen product forms a film on the "clean and moderately dry" skin surface, so that the test image can truly reflect the film forming ability of the product itself, rather than the result of external interference.

[0084] In an embodiment of the present application, when applying the influence medium and the test sample, the same application force and method are used, with an application amount of 0.02-0.03g per square centimeter, and after application, waiting for 8s before acquiring the test image.

[0085] It should be noted that by standardizing the force, method, amount, and time of application, different operators and different laboratories can obtain consistent basic conditions when testing according to the method, and the results can be reproduced. After eliminating the main human variables in the application process, the differences presented in the test images are more likely to be caused by the film-forming properties of the product itself rather than operational differences, making the final film-forming effect determination more convincing. The standardized operation process makes the test results available for horizontal comparison of different products, providing quantitative basis for product research and development and quality control.

[0086] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to cover all changes and modifications falling within the scope of the embodiments of the present application.

[0087] Finally, it should be noted that in this document, relational terms such as first and second and the like can only be used to distinguish one entity or action from another entity or action, and do not necessarily require or imply that there is any such actual relationship or order between or among the entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, so that a process, method, article, or terminal device including a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or terminal device. Without more limitations, an element defined by the statement "comprising a" does not exclude the existence of additional identical elements in the process, method, article, or terminal device including the element.

[0088] The above describes in detail the test method for the film-forming effect of a sunscreen product provided by the present application. The principles and implementation modes of the present application are described by using specific examples. The above description of the embodiments is only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation mode and application range; in summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for testing the film-forming effect of sunscreen products, characterized in that, Including the following steps: The test area of ​​the subject was cleaned and the subject sat quietly in a constant temperature and humidity environment for at least 30 minutes. Acquire contrast images using a facial spectral imager; Apply the influencing medium and the test sample to the area to be tested; Test images are acquired using a facial spectral imager, and the film-forming effect of the test sample is determined by comparing the comparison images with the test images.

2. The test method according to claim 1, characterized in that, The step of acquiring test images using a facial spectral imager and determining the film-forming effect level of the test sample by comparing the comparison image with the test image includes: The parameter changes in the comparison image and the test image are verified to follow a normal distribution. If the distribution is normal, a paired sample test is performed on the comparison image and the test image to obtain the test result; or, if the distribution is non-normal, a signed-rank test is performed on the comparison image and the test image to obtain the test result. The film-forming effect is determined based on the test results.

3. The test method according to claim 2, characterized in that, Before the step of verifying the normal distribution of the parameter change values ​​of the comparison image and the test image, the method further includes: Based on the comparison image, comparison parameters are obtained, including comparison skin uniformity, comparison brightness value, comparison whiteness value, and comparison pore area ratio. Test parameters are obtained based on the test image, including test skin uniformity, test brightness value, test whiteness value, and test pore area ratio.

4. The test method according to claim 2, characterized in that, When performing a signed-rank test on the comparison image and the test image, the significance level was set at 0.

05.

5. The test method according to claim 2, characterized in that, The step of verifying the normal distribution of parameter changes between the comparison image and the test image is as follows: if the significance value is greater than 0.05, it is a normal distribution; if the significance value is less than or equal to 0.05, it is a non-normal distribution.

6. The test method according to claim 1, characterized in that, The medium affecting the product is a customer-supplied cosmetic product.

7. The test method according to claim 6, characterized in that, Safety and impact tests were conducted on the customer-supplied cosmetics.

8. The test method according to claim 1, characterized in that, The test area is the face; the comparison images include a front view comparison, a left view comparison, and a right view comparison; the test images include a front view test, a left view test, and a right view test.

9. The test method according to claim 1, characterized in that, In the step of cleaning the test area of ​​the subject, a non-irritating facial cleanser is used for cleaning, and the moisture is then absorbed with a clean disposable towel or lint-free paper towel.

10. The test method according to claim 1, characterized in that, When applying the influencing medium and the test sample, use the same application force and method, apply evenly at a rate of 0.02-0.03g per square centimeter, and wait 8 seconds after application before acquiring the test image.

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