Skin Coating Film Formation Through Solvent-Driven Phase Separation
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Solution Overview
Problem
Existing cosmetic methods using inorganic fine particles to scatter or reflect light on the skin often result in uneven distribution, making skin imperfections more noticeable and leading to makeup deterioration due to particle migration and deformation with facial expressions.
Innovation Solution
A coating film is formed using a liquid composition containing solvents A and B with specific Hansen solubility parameters and a polymer C, where solvent A has a boiling point below 99°C and solvent B above 150°C, and polymer C is soluble in A but insoluble in B, forming primary particles with a core-shell structure that scatter light and provide elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If inorganic fine particles are used to scatter or reflect light on the skin, then the appearance of skin unevenness is improved, but the particles become unevenly distributed and migrate, making skin imperfections more noticeable and causing makeup deterioration
Solution Approach 1:
The patent changes the physical and chemical parameters of the coating material by using a polymer with specific solubility characteristics (soluble in solvent A, insoluble in solvent B) and controlling solvent evaporation rates. This transforms the particle distribution mechanism from passive settling to active control during drying, preventing migration while maintaining light scattering properties
Solution Approach 2:
The patent utilizes phase transition of the solvent system during evaporation. By employing two solvents with different boiling points and solubility parameters, the coating undergoes controlled phase separation during drying, forming stable primary particles that prevent makeup deterioration while maintaining the desired optical effects
2Illumination intensity
If inorganic fine particles are applied to the skin, then light scattering is achieved, but the particles deform with facial expressions, leading to makeup deterioration
Solution Approach 1:
The patent creates a composite coating system where polymer particles are dispersed in a specific solvent combination. This composite structure allows the coating to adapt to facial expressions while maintaining particle position stability, as the polymer matrix provides elasticity and the controlled solvent evaporation prevents particle migration during skin movement
3Reliability
If a coating film is formed using specific solvent combinations and polymers, then particle migration is prevented and makeup durability is enhanced, but the formulation complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for the solvents (boiling points, Hansen solubility parameters) and polymer properties to achieve optimal performance. By defining these parameters precisely, the formulation achieves stable particle distribution and prevented migration while providing clear guidelines for reproduction, managing complexity through standardization
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
The method achieves excellent concealment of skin unevenness and enhances makeup durability by preventing particle migration and maintaining film integrity despite facial deformations.
Implementation Method 1
a boiling point of the solvent A is lower than 99° C.
Implementation Method 2
the solvent B is compatible with the solvent A, and the polymer C is soluble in the solvent A but insoluble in the solvent B
Implementation Method 3
a distance Ra of the Hansen solubility parameter of the solvent A to water as expressed by the following equation (1) is 36 or less
Implementation Method 4
there have been made attempts to scatter or reflect incident light on the skin by blending spherical or plate-like inorganic fine particles
Implementation Method 5
a method for forming a coating film including a step of coating a liquid composition I containing a solvent A, a solvent B, and a polymer C to skin
Data Source
AI summary
The present invention relates to a method for forming a coating film including a step of coating a liquid composition I containing a solvent A, a solvent B, and a polymer C to skin, wherein a boiling point of the solvent A is lower than 99° C., and a distance Ra of the Hansen solubility parameter of the solvent A to water is 36 or less; a boiling point of the solvent B is 150° C. or higher, and a distance Ra of the Hansen solubility parameter of the solvent B to water is 40 or more; and the solvent B is compatible with the solvent A, and the polymer C is soluble in the solvent A but insoluble in the solvent B.