Composite UV Screening Particles for Transparent Sunscreen
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Solution Overview
Problem
Conventional antisun compositions based on inorganic UV screening agents, such as titanium oxide, suffer from uneven distribution on the skin, a whitening effect, and instability, which compromises their photoprotective efficacy and cosmetic appeal.
Innovation Solution
An oil-in-water emulsion containing a mixture of spherical and non-spherical composite particles with inorganic UV-screening agents, where the particles have a specific size range and are dispersed in a cosmetically acceptable medium, ensuring homogeneous distribution and avoiding a white deposit on the skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic UV screening agents (e.g., titanium oxide) are used to protect skin from UV radiation, then photoprotective efficacy is improved, but uneven distribution and whitening effect occur
Solution Approach 1:
The patent uses composite particles formed by encapsulating inorganic UV screening agents (titanium oxide, zinc oxide) within a polymer matrix (styrene/acrylate copolymer). This composite structure allows the inorganic particles to maintain their UV screening function while the polymer matrix ensures uniform dispersion and prevents aggregation, thereby eliminating uneven distribution and whitening effects while preserving photoprotective efficacy.
Solution Approach 2:
The polymer matrix acts as a flexible shell encapsulating the inorganic particles. This shell structure prevents direct contact between inorganic particles and the skin surface, reducing whitening effects, while also ensuring uniform distribution during application. The shell maintains the functional properties of the core inorganic particles for UV protection.
2Reliability
If high concentration of inorganic screening agents is used to ensure adequate UV protection, then photoprotective efficacy is improved, but cosmetic acceptability deteriorates due to whitening effect
Solution Approach 1:
By incorporating inorganic particles within a polymer matrix, the patent achieves efficient UV screening at lower concentrations. The composite structure enhances the optical properties and distribution uniformity, allowing adequate photoprotection with reduced whitening effects, thereby improving cosmetic acceptability while maintaining efficacy.
Solution Approach 2:
The patent modifies the physical and optical parameters of the screening system by embedding inorganic particles in a polymer matrix. This changes the light scattering and absorption characteristics, reducing the whitening effect while maintaining UV blocking capability, thus improving cosmetic appearance without sacrificing photoprotective performance.
3Reliability
If conventional metal oxide pigments are used for UV screening, then photoprotection is provided, but homogeneity of distribution deteriorates
Solution Approach 1:
The polymer matrix composite encapsulates individual inorganic particles, preventing their aggregation and ensuring uniform dispersion throughout the cosmetic formulation. This composite approach maintains stable, homogeneous distribution during storage and application, while the inorganic core continues to provide reliable UV protection.
Solution Approach 2:
The polymer shell surrounding each inorganic particle acts as a stabilizing layer that prevents particle aggregation and ensures uniform distribution. This shell structure maintains homogeneity throughout the formulation, allowing consistent photoprotective performance across the entire product application area.
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 photoprotection with improved cosmetic qualities, including stability and spreadability, while maintaining a transparent appearance on the skin.
Implementation Method 1
for the photoprotection of the skin and/or hair against ultraviolet (UV) radiation... UV-B rays, known as UV-B rays, cause skin burns and erythema... UV-A rays, with wavelengths between 320 and 400 nm, which cause tanning of the skin
Implementation Method 2
fine TiO2 particles to protect the skin from UV rays... inorganic screening agents... result in an uneven, inhomogeneous or even coarse distribution of said pigments
Data Source
AI summary
The present invention concerns a composition in the form of an oil-in-water emulsion containing, in a cosmetically acceptable medium, a mixture of composite particles comprising: a) at least spherical composite particles A with a mean size of between 0.1 and 30 µm comprising a matrix and an inorganic UV-screening agent, the content of inorganic screening agent in a particle ranging from 1% to 70% by weight, b) at least non-spherical composite particles B with a mean size of between 0. and 30 µm comprising a matrix and an inorganic UV-screening agent, the content of inorganic screening agent in a particle ranging from 1% to 70% by weight.