Low Molecular Weight Polymer Water-in-Oil Sunscreen Emulsion
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Solution Overview
Problem
Current sunscreen cosmetic compositions, particularly water-in-oil emulsions, face challenges in achieving enhanced UV protective effects over a broad UV radiation region while maintaining a smooth, non-sticky, and dry feel, often compromising on stability due to the incorporation of high molecular weight water-soluble polymers.
Innovation Solution
Incorporating a water-soluble polymer in the aqueous phase of a water-in-oil emulsion sunscreen cosmetic composition, in combination with a UV absorbent, to significantly enhance UV absorption capability and improve the cosmetic feel, with specific concentrations of 0.01-10% polymer and 0.01-30% UV absorbent, and a viscosity of at most 10,000 mPa·s.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high molecular weight water-soluble polymers are incorporated into water-in-oil emulsion sunscreen compositions, then UV protective effect is enhanced, but viscosity increases and feeling in use deteriorates (sticky feeling)
Solution Approach 1:
The patent changes the molecular weight parameter of the water-soluble polymer from high (conventional) to low (5,000-500,000), which maintains UV protective capability while eliminating the sticky feeling and excessive viscosity associated with high molecular weight polymers. This parameter optimization resolves the contradiction between UV protection and sensory comfort.
Solution Approach 2:
The patent creates a composite system combining low molecular weight water-soluble polymers with specific surfactants and UV absorbents in a water-in-oil emulsion matrix. This composite approach enhances UV protection through synergistic interactions while the low molecular weight polymer avoids the adverse sensory effects of conventional high molecular weight polymers.
2Object-affected harmful factors
If water-soluble polymer is incorporated into water-in-oil emulsion, then UV absorption capability is enhanced, but viscosity increases
Solution Approach 1:
The patent optimizes the molecular weight parameter of the water-soluble polymer to the range of 5,000-500,000, which is sufficiently low to maintain acceptable viscosity (preventing excessive thickening) while still providing effective UV absorption enhancement. This parameter control resolves the contradiction between UV absorption capability and viscosity.
3Reliability
If conventional water-in-oil emulsion is used, then waterproofness is improved, but UV protective effect over broad UV region is insufficient
Solution Approach 1:
The patent develops a composite sunscreen system within the water-in-oil emulsion framework, combining low molecular weight water-soluble polymers, specific surfactants, and multiple UV absorbents. This composite formulation maintains the inherent waterproofness of water-in-oil emulsions while significantly enhancing broad-spectrum UV protective capability through synergistic interactions among the components.
Solution Approach 2:
The low molecular weight water-soluble polymer serves multiple functions simultaneously: it enhances UV absorption capability across broad spectrum, maintains acceptable viscosity, and does not compromise the waterproofness characteristic of water-in-oil emulsions. This multi-functionality resolves the contradiction between maintaining waterproofness and enhancing UV protection.
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 solution results in a low-viscosity water-in-oil emulsion sunscreen with significantly improved UV protective effects and superior cosmetic feel, including smoothness, dryness, and non-stickiness, outperforming traditional compositions in both UV protection and application experience.
Implementation Method 1
the UV absorption capability thereof, owing to the combined use of the UV absorbent and the water-soluble polymer therein
Data Source
AI summary
To provide a low-viscosity water-in-oil emulsion sunscreen cosmetic composition which is extremely excellent in UV protective enhancing effect (as the protective boosting effect of the UV absorption capability thereof) over a broad UV radiation region and has superior feeling in use (smooth feeling, dry feeling, and non-sticky feeling, etc.). A water-in-oil emulsion sunscreen cosmetic composition comprising (a) from 0.01 to 10% by mass of a water-soluble polymer and (b) from 0.01 to 30% by mass of a UV absorbent, and having a viscosity of at most 10,000 mPa·s (as measured with a B-type viscometer at 30° C.), wherein the aqueous phase accounts for at most 45% by mass.