Anhydrous Pigmented Sunscreen Stabilization via Silica Mediation
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Solution Overview
Problem
Combining color pigments with organic UV-filters in personal care products creates a complex formulation that is difficult to stabilize, particularly in high oil and particulate compositions.
Innovation Solution
A method involving the sequential addition of hydrophobic and hydrophilic silica to a lipid phase, with high-speed rotary mixing to achieve phase stability, including the steps of adding hydrophobic silica, homogenizing, adding hydrophilic silica, and re-homogenizing, which stabilizes anhydrous compositions with high oil and particulate levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If color pigments are combined with organic UV-filters in personal care products, then the product provides both color and UV protection functionality, but the formulation becomes complex and difficult to stabilize
Solution Approach 1:
The patent uses silica particles as intermediary agents to mediate between the color pigments and organic UV-filters. The silica surface, particularly when modified with specific surface treatments, acts as a platform that can interact with both pigments and UV-filters, preventing their direct interaction that would cause phase instability. This intermediary approach allows the formulation to maintain both color and UV protection while achieving phase stability.
Solution Approach 2:
The patent employs parameter changes by modifying the surface properties of silica particles through chemical treatment (creating hydrophobic or hydrophilic surfaces). By changing the surface polarity parameter of the silica, the formulation can accommodate different combinations of color pigments and organic UV-filters with varying polarities, thereby achieving stable formulations across different product types.
2Quantity of substance
If high levels of oil and particulates are included in the composition, then the product provides adequate color and UV protection, but phase separation and exudation occur under temperature variations
Solution Approach 1:
The patent creates a composite material system where silica particles are integrated into the oil-based formulation containing color pigments and UV-filters. The silica acts as a structural framework that holds the oil, pigment, and UV-filter components together, preventing phase separation even at high temperatures. This composite approach allows maintaining high levels of oil and particulates while achieving temperature stability.
Solution Approach 2:
The patent applies local quality by creating regions around silica particles where the concentration and distribution of oil, pigment, and UV-filter are optimized. The silica particles create localized stable domains within the formulation, where the micro-environment around each particle is tailored to prevent separation, while the bulk formulation maintains high oil and particulate content for adequate color and 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 method effectively stabilizes anhydrous, pigmented sunscreen compositions, ensuring phase stability even under elevated and room temperature conditions, as demonstrated by passing stability tests without phase separation or exudation.
Implementation Method 1
adding a hydrophobic silica to a lipid phase comprising a dispersed color pigment and an organic UV-filter; adding a hydrophilic silica to the lipid phase comprising hydrophobic silica
Implementation Method 2
homogenizing the lipid phase comprising the hydrophobic silica by rotary mixing at a rotation speed of at least 1000 rpm; re-homogenizing the lipid phase comprising the hydrophobic silica and the hydrophilic silica by rotary mixing at a rotation speed of at least 1000 rpm
Data Source
AI summary
The invention relates to a method of making an anhydrous, pigmented sunscreen composition. The method comprises first adding a hydrophobic silica to a lipid phase comprising a dispersed color pigment and an organic UV-filter and homogenizing the mixture. Next, a hydrophilic silica is added and rehomogenization is performed.