Sunscreen Emulsion Using Superhydrophilic Copolymers to Reduce Irritation
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Solution Overview
Problem
Existing sunscreen compositions often irritate the skin or sting the eyes, and there is a need for phase-stable, low-irritation sunscreens that include superhydrophilic amphiphilic copolymers and are essentially free of monomeric surfactants.
Innovation Solution
A phase-stable oil-in-water emulsion sunscreen composition comprising a continuous water phase with a superhydrophilic amphiphilic copolymer and a suspension of styrene/acrylate copolymer particles, where the copolymer is a polysaccharide modified with hydrophobic reagents, and a discontinuous oil phase with a UV-absorbing compound, with a monomeric surfactant concentration of 0.75% or less and Brookfield viscosity of 2000cps or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional sunscreen compositions are used, then UV protection is provided, but skin irritation and eye stinging occur
Solution Approach 1:
The patent changes the chemical parameters by replacing monomeric surfactants with polymeric surfactants (superhydrophilic amphiphilic copolymers with molecular weights of 1,000 to 200,000 Daltons). This parameter change maintains emulsification capability while reducing skin irritation and eye stinging, as the polymeric structure provides gentler surfactant action compared to monomeric alternatives.
Solution Approach 2:
The invention uses composite material structures by combining superhydrophilic amphiphilic copolymers with styrene/acrylate copolymer particles and UV-absorbing compounds in an oil-in-water emulsion system. This composite approach creates a multifunctional formulation that provides UV protection, emulsification, and skin conditioning while minimizing irritation.
2Object-affected harmful factors
If polymeric surfactants are used to reduce irritation, then skin mildness improves, but phase stability may be compromised
Solution Approach 1:
The patent specifies precise parameter ranges for the polymeric surfactants, including molecular weights of 1,000 to 200,000 Daltons and specific concentrations (0.1% to 10% by weight). These controlled parameter changes optimize both the mildness to skin and the phase stability of the emulsion, preventing separation while maintaining low irritation.
Solution Approach 2:
The superhydrophilic amphiphilic copolymers act as intermediary substances that mediate between the oil phase (containing UV absorbers) and water phase. These polymeric surfactants stabilize the oil-in-water emulsion interface, ensuring phase stability while providing skin-conditioning benefits and reducing irritation.
3Object-affected harmful factors
If monomeric surfactants are eliminated, then skin irritation reduces, but emulsion stability may be affected
Solution Approach 1:
The invention creates a composite emulsion system where polymeric surfactants work synergistically with styrene/acrylate copolymer particles and UV-absorbing compounds. This composite structure provides emulsion stability equivalent to or better than monomeric surfactant systems while eliminating the irritation associated with monomeric surfactants.
Solution Approach 2:
The patent specifies that the composition contains 0% to 0.75% by weight of monomeric surfactant, representing a parameter change from conventional formulations that rely heavily on monomeric surfactants. This reduction, combined with the use of polymeric surfactants at optimized concentrations, maintains emulsion stability while reducing irritation.
4Ease of operation
If superhydrophilic amphiphilic copolymers are used, then foaming properties improve, but formulation complexity increases
Solution Approach 1:
The superhydrophilic amphiphilic copolymers perform multiple functions simultaneously: they act as polymeric surfactants for emulsification, provide foaming properties for consumer acceptability, and offer skin-conditioning benefits. This multi-functionality reduces the need for separate ingredients, thereby simplifying the overall formulation despite the advanced polymer chemistry involved.
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 composition achieves low irritation and high foaming properties while maintaining phase stability, forming a mild and effective sunscreen that is free of monomeric surfactants, enhancing skin protection without causing irritation.
Implementation Method 1
a phase-stable, oil-in-water emulsion, comprising, a continuous water phase comprising a superhydrophilic amphiphilic copolymer
Implementation Method 2
the discontinuous oil phase comprising a UV absorbing compound
Data Source
AI summary
The sunscreen compositions of the present invention include a phase-stable, oil-in-water emulsion that includes a continuous water phase containing a superhydrophilic amphiphilic copolymer and a suspension of styrene/acrylate copolymer particles; and a discontinuous oil phase homogeneously dispersed in the continuous water phase, where the discontinuous oil phase includes a UV absorbing compound and the sunscreen composition is essentially free of monomeric surfactant and has a viscosity of about 2000cps or less.