UV-absorbing polymer sunscreen with reduced eye irritation
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Solution Overview
Problem
Current sunscreen compositions often irritate the eyes and contain non-polymeric UV-absorbers, making it challenging to develop eye-mild, aesthetically pleasing sunscreens with polymeric UV-absorbing compounds that are substantially free of these additives.
Innovation Solution
A sunscreen composition featuring a discontinuous oil phase stabilized in a continuous water phase, incorporating a UV-absorbing polymer with high molecular weight and low water solubility, along with an oil-gelling polymer, while being substantially free of non-polymeric UV-absorbers and emulsifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-polymeric UV-absorbers are used in sunscreen compositions, then UV protection is improved, but eye irritation increases
Solution Approach 1:
The patent changes the molecular weight parameter of UV-absorbing compounds from low (non-polymeric) to high (polymeric, 2000-1,000,000+ Daltons). This parameter change maintains UV protection capability while reducing eye irritation, as the larger polymeric molecules do not penetrate the eye as readily as smaller non-polymeric UV-absorbers
Solution Approach 2:
The patent uses composite polymeric structures that incorporate UV-absorbing moieties within polymer backbones. These composite materials combine the UV-protection function with the beneficial properties of polymers (higher molecular weight, lower penetration), thereby achieving both UV protection and reduced eye irritation
2Object-affected harmful factors
If polymeric UV-absorbers with high molecular weight are used, then eye irritation is reduced, but formulation complexity increases
Solution Approach 1:
The patent optimizes the molecular weight parameter range of polymeric UV-absorbers to 2000-1,000,000 Daltons, finding a balance point where eye irritation is sufficiently reduced while maintaining formulation simplicity. This parameter optimization ensures the polymers are not so large as to create excessive formulation challenges
Solution Approach 2:
The patent introduces emulsifiers and stabilizers as auxiliary components to specifically address the formulation challenges posed by polymeric UV-absorbers. These additional ingredients locally resolve the complexity issue by improving dispersion and stability, allowing the main polymeric UV-absorbers to function effectively
3Object-affected harmful factors
If polymeric UV-absorbers are used to reduce eye irritation, then skin tolerance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies pre-synthesis of polymeric UV-absorbers with controlled molecular weights and incorporated UV-absorbing moieties. This preliminary preparation of specialized polymers simplifies the final formulation manufacturing, as the UV-protection function is already built into the polymer structure rather than requiring complex assembly steps
Solution Approach 2:
The patent uses emulsifiers and stabilizers as intermediary substances that facilitate the incorporation of polymeric UV-absorbers into the sunscreen formulation. These intermediaries simplify manufacturing by ensuring proper dispersion and stability during the formulation process, reducing processing difficulties
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 provides effective UV protection with a high sun protection factor (SPF) and low eye irritation, as demonstrated by high EPI-OCULAR values, indicating reduced eye irritation and enhanced skin tolerance.
Implementation Method 1
an ultraviolet radiation-absorbing polymer, (i.e., 'UV-absorbing polymer'), having a molecular weight greater than about 2,000 Daltons and comprising one or more UV-absorbing moieties
Implementation Method 2
The composition includes an oil-gelling polymer
Implementation Method 3
a discontinuous oil phase stabilized in a continuous water phase
Data Source
AI summary
Aqueous compositions including a discontinuous oil phase containing an ultraviolet radiation-absorbing polymer stabilized in a continuous aqueous phase, an oil-gelling polymer, and which are substantially free of non-polymeric ultraviolet radiation-absorbers.