Surface-Modified Cerium Oxide Sunscreen for UVA1 Protection
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Solution Overview
Problem
Current inorganic sunscreens like titanium dioxide and zinc oxide have limitations, including inability to absorb UVA1 wavelengths, causing white cast due to high refractive index and photocatalytic activity, which leads to skin issues and formulation instability.
Innovation Solution
A sunscreen composition using cerium oxide particles surface-modified with fatty acids, which absorb UVA1 wavelengths, reduce white cast, and minimize photocatalytic activity, enhancing emulsification and dispersion stability while maintaining safety and effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium dioxide or zinc oxide are used as inorganic sunscreens, then UVB and UVA2 protection is improved, but UVA1 absorption is insufficient
Solution Approach 1:
The patent combines titanium dioxide and zinc oxide particles to create a composite sunscreen formulation. This merging of two different inorganic sunscreen materials allows the composition to benefit from their complementary UV absorption properties, achieving broader spectrum coverage including UVA1 wavelengths while maintaining UVB and UVA2 protection.
Solution Approach 2:
The invention uses a composite material system consisting of titanium dioxide and zinc oxide particles with specific size distributions. By creating a composite formulation rather than using a single material, the patent achieves enhanced UV protection across all three wavelength regions (UVB, UVA2, and UVA1) that neither material could achieve alone.
2Reliability
If titanium dioxide or zinc oxide are used, then sun protection power is improved, but white cast phenomenon occurs due to high refractive index
Solution Approach 1:
The patent segments the inorganic sunscreen material into two distinct particle types with different refractive indices - titanium dioxide particles and zinc oxide particles. By dividing the sunscreen function between these two materials rather than using a single material, the formulation achieves effective UV protection while reducing the overall white cast effect through the complementary optical properties of the segmented components.
Solution Approach 2:
The invention applies local quality by using particles of different sizes (0.01-1 μm range) with different refractive indices in different proportions throughout the formulation. This spatial and functional differentiation allows certain regions to provide stronger UV protection while other regions minimize visual appearance issues, achieving both high sun protection power and reduced white cast.
3Reliability
If titanium dioxide or zinc oxide are used, then UV absorption is improved, but photocatalytic activity causes component denaturation and pigmentation
Solution Approach 1:
The patent introduces an intermediary substance - a surfactant or coating material - that covers the surface of the titanium dioxide and zinc oxide particles. This intermediary layer acts as a barrier between the photocatalytically active inorganic particles and the organic formulation components, preventing direct interaction that would lead to denaturation and pigmentation while allowing the particles to maintain their UV absorption functionality.
Solution Approach 2:
The invention converts the harmful photocatalytic activity into a beneficial effect by using the surface of the inorganic particles as a platform for attaching UV-filtering organic compounds or stabilizing agents. The photocatalytic surface, which would normally cause degradation, is instead utilized to enhance the overall UV protection mechanism and improve formulation stability through controlled surface chemistry.
4Object-affected harmful factors
If surface is covered with aluminum oxide or silicon dioxide to reduce photocatalytic power, then safety is improved, but powder texture becomes heavy and application becomes hard and dry
Solution Approach 1:
The patent changes the key parameter of surface coating material from traditional aluminum oxide or silicon dioxide to alternative materials with different physical and chemical properties. By selecting coating materials with lower density, better flexibility, and improved compatibility with cosmetic formulations, the invention maintains the protective function of reducing photocatalytic activity while dramatically improving powder texture, application softness, and spreadability characteristics.
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 cerium oxide-based sunscreen composition provides broad-spectrum UV protection, prevents white cast, and ensures stability and spreadability, making it suitable for cosmetic applications.
Implementation Method 1
cerium oxide particles that are surface-modified with a fatty acid... capable absorbing UVA1
Implementation Method 2
inorganic sunscreen is representatively a physical sunscreen that reflects, scatters, and absorbs light
Implementation Method 3
inorganic sunscreen is representatively a physical sunscreen that reflects, scatters, and absorbs light
Data Source
AI summary
The present invention provides a sunscreen composition comprising cerium oxide (CeO2) particles surface-modified with a saturated fatty acid having 10 to 30 carbon atoms or an unsaturated fatty acid having 10 to 30 carbon atoms. Since the sunscreen composition according to an embodiment of the present invention exhibits a high kinematic viscosity in the low-frequency region and high-frequency region, the formulation has excellent emulsification/dispersion phase stability and excellent spreadability, and thus the sunscreen composition can be effectively used as a cosmetic composition for blocking ultraviolet rays.