Tinted Sunscreen Emulsion Stability via Surfactant Mediation
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Solution Overview
Problem
Existing tinted cosmetic sunscreen compositions face challenges in achieving high SPF and UVA/UVB protection while maintaining stability and sensory attributes, particularly with high amounts of colored pigments and UV filters, which often result in migration and discoloration issues, especially in darker shades.
Innovation Solution
A tinted cosmetic sunscreen composition comprising 5.0-6.5% colored pigments, 1.7-1.9% glyceryl stearate and PEG-100 stearate, 1.4-1.6% potassium cetyl phosphate, and 15.0-25.0% UV filters, formulated as an oil-in-water emulsion, providing a balance of photoprotection and color coverage without heavy feel or pigment migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high amounts of colored pigments and UV filters are used to achieve high SPF and UVA/UVB protection with high coverage, then photoprotection and color coverage are improved, but stability deteriorates due to pigment migration and discoloration
Solution Approach 1:
The patent introduces specific surfactants (glyceryl stearate and PEG-100 stearate in a 3:7 weight ratio) as intermediary substances that mediate between the colored pigments/UV filters and the aqueous phase. These surfactants act as stabilizing agents that prevent pigment migration and discoloration while maintaining high SPF and coverage, thus resolving the contradiction between photoprotection effectiveness and formulation stability
Solution Approach 2:
The patent changes the chemical composition parameters by specifying precise ratios of glyceryl stearate (1.7-1.9%) and PEG-100 stearate (1.4-1.6%), along with potassium cetyl phosphate (1.4-1.6%). This parameter optimization ensures that the emulsion maintains stability even with high concentrations of pigments and UV filters, preventing the migration and discoloration issues that typically occur
2Quantity of substance
If high amounts of colored pigments are used to provide high coverage and tinting capability, then color coverage is improved, but sensory perception deteriorates due to heavy feel on skin
Solution Approach 1:
The patent optimizes the pigment concentration parameter to a specific range (5.0-6.5%) and combines it with optimized surfactant ratios. This parameter control ensures sufficient color coverage for high coverage claims while preventing the formulation from feeling heavy on the skin, thus resolving the contradiction between pigment quantity and sensory perception
3Reliability
If complex systems with high amounts of UV filters and pigments are used to achieve high SPF and coverage, then photoprotection and coverage are improved, but manufacturing stability deteriorates due to pigment migration and separations
Solution Approach 1:
The patent uses glyceryl stearate and PEG-100 stearate as intermediary emulsifying agents that facilitate uniform distribution of pigments and UV filters throughout the aqueous phase. This intermediary action prevents separations and ensures manufacturing precision while maintaining high SPF and coverage effectiveness
Solution Approach 2:
The patent creates a composite emulsion system combining multiple components: colored pigments, UV filters, glyceryl stearate, PEG-100 stearate, and potassium cetyl phosphate. This composite formulation achieves synergistic effects where the combined system provides both high photoprotection effectiveness and manufacturing stability, preventing pigment migration and separations
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 high SPF and UVA/UVB protection with stable pigment distribution, maintaining sensory benefits like smooth application and preventing pigment migration, suitable for various skin tones.
Implementation Method 1
formulated as an oil-in-water emulsion
Implementation Method 2
glyceryl stearate (and) PEG-100 stearate
Implementation Method 3
potassium cetyl phosphate
Implementation Method 4
at least one UV filter... provide good protection against the sun rays
Data Source
AI summary
The present invention is directed to new tinted cosmetic sunscreen compositions, comprising (a) at least one colored pigment selected from titanium dioxide, iron oxides and mixtures thereof, (b) glyceryl stearate (and) PEG-100 stearate, (c) potassium cetyl phosphate, and (d) at least one UV filter. The present invention is also directed to the use of a tinted cosmetic sunscreen composition, and to a process for manufacturing a tinted cosmetic sunscreen composition.