Silane-Coated Mineral Sunscreen for Smooth Spreadability
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Solution Overview
Problem
Sunscreen compositions with high concentrations of mineral sunscreen actives (>10.0 wt. %) face challenges such as increased drag and difficulty in smooth application due to hardness and poor spreadability on the skin.
Innovation Solution
A sunscreen composition incorporating a metal oxide sunscreen active (zinc oxide or titanium dioxide) in the range of 3.0 wt. % to 20.0 wt. %, combined with emollients like C12-C15 alkyl benzoate, dimethicone, and humectants like glycerin, along with emulsifiers and film formers, to enhance application and performance attributes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of mineral sunscreen actives is increased to provide stronger UV protection, then the sunscreen effectiveness is improved, but the composition becomes harder to spread and apply smoothly on skin
Solution Approach 1:
The patent changes the physical and chemical parameters of the mineral sunscreen actives by coating them with silane-based compounds and performing silane modification. This treatment reduces particle surface energy and improves dispersion characteristics, allowing higher concentrations (10-30 wt%) to be incorporated while maintaining smooth spreadability and reducing drag during application.
Solution Approach 2:
The patent creates composite structures by coating mineral sunscreen particles with silane-based compounds and crosslinking them to form a network structure. This composite approach combines the UV-blocking properties of mineral actives with the beneficial rheological properties of the silane matrix, enabling high concentration formulations that remain easy to apply.
2Reliability
If the concentration of mineral sunscreen actives is increased to provide stronger UV protection, then the sunscreen effectiveness is improved, but the composition exhibits increased drag and is harder to smooth into skin
Solution Approach 1:
The patent modifies the surface parameters of mineral sunscreen particles through silane coating and crosslinking. This changes the interfacial properties between particles and the continuous phase, reducing friction and drag forces during application. The silane-modified particles exhibit improved flow characteristics even at high concentrations.
Solution Approach 2:
The silane-based compound acts as an intermediary between the mineral sunscreen particles and the continuous phase. This intermediary layer improves particle dispersion and reduces particle-particle and particle-skin interactions, thereby reducing drag and improving smoothness during application.
3Reliability
If high concentration of mineral sunscreen actives is used to ensure adequate UV protection, then the protection performance is improved, but the composition becomes relatively harder to spread onto skin
Solution Approach 1:
The patent applies silane modification to change the surface parameters of mineral particles, reducing their tendency to aggregate and improving their wettability. This allows high concentrations to be incorporated while maintaining good spreadability and ease of application on skin surfaces.
Solution Approach 2:
The silane coating provides local quality improvement at the particle surface, creating a region with different rheological properties than the bulk mineral particles. This localized modification at the particle level translates to improved macroscopic spreadability of the entire formulation.
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 improved rub-in, spreadability, and reduced sticky/tackiness, maintaining effectiveness with high mineral sunscreen active concentrations, while maintaining protection against UVA and UVB radiation.
Implementation Method 1
Ultraviolet (UV) solar radiation falling within the UVA region (320 nm to 400 nm) is damaging... UVB radiation is absorbed by the epidermis layer... sunscreen compositions include one or more sunscreen actives to protect keratinous substrates, such as skin and hair, from UV radiation
Implementation Method 2
One traditional category of sunscreen actives is inorganic, or mineral, sunscreen actives... The sunscreen active may include a metal oxide selected from zinc oxide, titanium dioxide
Implementation Method 3
The emollient may include a benzoate ester. In one example, the benzoate ester may include C12-C15 alkyl benzoate... a sunscreen composition that is relatively easy to spread onto skin
Implementation Method 4
The composition includes an emulsifier... emulsifiers and film formers, to enhance application and performance attributes
Implementation Method 5
The composition includes a film former... film formers, to enhance application and performance attributes
Data Source
AI summary
A sunscreen composition includes a metal oxide sunscreen active, an emollient including a benzoate ester and an organosilicon compound, an emulsifier, and one or more other ingredients such as water. The metal oxide may be present in an amount between about 3.0 wt. % to about 20.0 wt. %, the benzoate ester may be present in an amount between about 5.0 wt. % to about 30.0 wt. %, the organosilicon compound may be present in an amount of about 3.5 wt. %, the emulsifier may be present in an amount between about 2.0 wt. % to about 10.0 wt. %, and water may be present in an amount of 30.0 wt. % or more, based on the total weight of the sunscreen composition. The sunscreen composition may be in the form of lotion that does not foam and is rubbed in to contact the keratinous surface.