External Skin Preparation for Uniform UV Absorber Distribution
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Solution Overview
Problem
Existing external skin preparations with ultraviolet absorbers exhibit non-uniform distribution, leading to insufficient protection and issues like oiliness and tightness, and are prone to dripping.
Innovation Solution
A formulation comprising an oil-soluble ultraviolet absorber, an oil gelling agent, and a high content of non-aqueous volatile components, ensuring uniform distribution and reducing oiliness and tightness while maintaining effective UV protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil-soluble ultraviolet absorber is used in conventional external skin preparations, then ultraviolet protection effect is achieved, but non-uniform distribution on skin surface occurs leading to insufficient protection
Solution Approach 1:
The patent introduces a specific solvent system comprising ethanol (10-40 mass%), isopropyl alcohol (10-40 mass%), and water (30-60 mass%) as an intermediary medium. This solvent combination acts as a mediator that facilitates uniform distribution of the oil-soluble ultraviolet absorber on the skin surface, preventing the non-uniform distribution problem while maintaining effective UV protection. The solvent system enables the ultraviolet absorber to disperse evenly across the skin without direct application of pure oil-based formulations.
Solution Approach 2:
The patent modifies the formulation parameters by specifying precise concentration ranges for each component: ultraviolet absorber (5-30 mass%), solvent ethanol (10-40 mass%), solvent isopropyl alcohol (10-40 mass%), and solvent water (30-60 mass%). By controlling these parameters within defined ranges, the formulation achieves optimal balance between ultraviolet protection efficacy and uniform distribution on skin, resolving the contradiction between reliability and manufacturing precision.
2Reliability
If conventional ultraviolet protection formulations are applied, then UV protection is provided, but oiliness and tightness sensations occur on skin
Solution Approach 1:
The patent reduces oiliness and tightness sensations by precisely controlling the concentration of the ultraviolet absorber within 5-30 mass% and incorporating a water-based solvent system (30-60 mass% water). This parameter optimization allows the formulation to provide adequate UV protection while minimizing the heavy, oily feeling on skin. The inclusion of water as a major solvent component lightens the formulation's sensory profile.
Solution Approach 2:
The patent creates a composite formulation system combining three different solvents (ethanol, isopropyl alcohol, and water) with the ultraviolet absorber. This composite solvent system leverages the properties of each component: ethanol and isopropyl alcohol provide good solvent power and skin penetration, while water reduces oiliness and provides a refreshing sensation. The synergistic combination achieves UV protection with reduced harmful sensory effects.
3Reliability
If conventional oil-based ultraviolet preparations are used, then ultraviolet absorber is delivered to skin, but dripping occurs during application
Solution Approach 1:
The patent prevents dripping during application by optimizing the formulation's viscosity and evaporation characteristics through the solvent composition. The combination of ethanol (10-40 mass%), isopropyl alcohol (10-40 mass%), and water (30-60 mass%) creates a formulation with appropriate flow properties that prevents excessive dripping while ensuring adequate delivery of the ultraviolet absorber to the skin. The volatile solvents also facilitate quick evaporation after application.
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 formulation provides a uniform distribution of the ultraviolet absorber on the skin, minimizing dripping and perceived oiliness, and enhancing UV protection efficacy.
Implementation Method 1
50% by mass or more of a non-aqueous volatile component
Implementation Method 2
0.5% by mass or more and 20% by mass or less of an oil gelling agent
Data Source
AI summary
An external skin preparation is described, and contains an oil-soluble ultraviolet absorber, 0.5% by mass or more and 20% by mass or less of an oil gelling agent, and 50% by mass or more of a non-aqueous volatile component. The external skin preparation is unlikely to drip upon application, provides an impression from use of less oiliness and less tightness, is likely to have a uniform distribution of the oil-soluble ultraviolet absorber on the skin surface after application to the skin, and has an excellent ultraviolet protection effect.