Cosmetic UV Evaluation Using Oil-Repellent Applicator Surfaces
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Solution Overview
Problem
Existing methods for evaluating UV protection performance of cosmetics are time-consuming, costly, and lack accuracy due to variations in measurements caused by different contact angles of substrates and applicator materials, leading to uneven application and inaccurate SPF and UVA-PF values.
Innovation Solution
Use of an applicator with a material layer having an oil adhesion prevention property and UV-transmittance-measurement transparent substrates with varying contact angles to form a uniform cosmetic layer, followed by spectrophotometric analysis to determine SPF and UVA-PF values using specific formulas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used with standard substrates, then measurement process is simple, but measurement precision deteriorates due to variations in contact angles causing uneven application
Solution Approach 1:
The invention changes the surface energy parameter of the applicator by using materials with different contact angles to water. This allows the applicator to adapt to cosmetics with different hydrophilicity/lipophilicity, ensuring uniform application and accurate measurement without complicating the overall measurement process
Solution Approach 2:
The applicator serves as an intermediary between the cosmetic and the substrate. By selecting applicator materials with appropriate surface properties (different contact angles), the invention mediates the interaction to achieve uniform application regardless of the cosmetic's physical properties, thereby improving measurement precision
2Reliability
If human subjects are used for UV protection testing, then measurement reliability is high, but loss of time and cost increase significantly
Solution Approach 1:
The invention creates a controlled in vitro measurement system that copies the essential conditions of in vivo testing. By using standardized substrates and applicators that ensure uniform cosmetic application, the system reproduces reliable UV protection measurements without requiring human subjects, thus eliminating the time loss and ethical issues while maintaining measurement reliability
Solution Approach 2:
The invention replaces the biological system (human skin) with a physical measurement system consisting of standardized substrates and spectrophotometric analysis. This substitution maintains measurement reliability through controlled conditions while dramatically reducing measurement time and eliminating ethical concerns
3Adaptability or versatility
If substrates with different contact angles are used to accommodate various cosmetic types, then adaptability improves, but device complexity and measurement time increase
Solution Approach 1:
The invention changes the applicator material parameter (contact angle to water) to match the cosmetic's hydrophilicity/lipophilicity characteristics. By having a set of applicators with different surface properties, the system can quickly select the appropriate applicator for each cosmetic type, ensuring uniform application and maintaining high measurement efficiency without requiring multiple substrate types
Solution Approach 2:
The invention performs preliminary selection of the appropriate applicator material based on the cosmetic's physical properties before measurement. This preliminary action ensures that the correct applicator is used from the start, avoiding the need to test multiple substrates and thereby maintaining high productivity while achieving broad adaptability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves precise and stable measurements across various cosmetic forms, including powder and stick-type products, with higher correlation to human test data, eliminating the need for corona-discharge treatment and reducing measurement time.
Implementation Method 1
an applicator having a material layer with a surface having an oil adhesion prevention property
Implementation Method 2
spectrophotometric analysis to determine SPF and UVA-PF values
Data Source
AI summary
A method for evaluating UV protection performance of a cosmetic includes a preparation step of preparing a measurement sample for evaluating UV protection performance of a target cosmetic, wherein the preparation step is a step including forming a uniform cosmetic application layer of the cosmetic on an UV-transmittance-measurement transparent substrate surface, by using a surface of an applicator having a layer made of a non-metal material constituting the surface that has an oil adhesion prevention property. According to the method, an UV transmission ratio of the cosmetic can easily and accurately be evaluated.