Sunscreen Emulsion with Crosslinked Siloxane Elastomer
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Solution Overview
Problem
Existing sunscreen compositions face challenges in stabilizing high levels of liposoluble UV filters, leading to issues like discoloration and precipitation, making it difficult to achieve long-term stability and effective photoprotection without a tacky or white residue on the skin.
Innovation Solution
A stable water-releasing emulsion composition containing high levels of liposoluble UV filters, utilizing a combination of stability-boosting polyols, emulsifying crosslinked siloxane elastomers, and dimethicone, which maintains stability and converts into droplets upon application, ensuring effective penetration and photoprotection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liposoluble UV filters are incorporated into emulsion-type compositions, then photoprotection capability is improved, but stability deteriorates due to discoloration, precipitation, and re-crystallization
Solution Approach 1:
The patent uses a specific emulsifying crosslinked siloxane elastomer as an intermediary substance that mediates between the liposoluble UV filters and the aqueous phase. This emulsifier forms a stable interface that prevents re-crystallization and separation, allowing high levels of liposoluble filters to be incorporated without compromising emulsion stability.
Solution Approach 2:
The patent changes the chemical parameters of the emulsion system by using a crosslinked siloxane elastomer with specific molecular structure and crosslinking density. This parameter change in the emulsifier's molecular architecture enables it to tolerate high concentrations of electrolytes from liposoluble UV filters without causing instability, discoloration, or precipitation.
2Reliability
If inorganic UV filters are used in large quantities, then photoprotection coverage is improved, but tactile sensation deteriorates due to dryness and white color residue
Solution Approach 1:
The patent creates a composite sunscreen formulation that combines organic liposoluble UV filters with a crosslinked siloxane elastomer emulsifier and aqueous phase. This composite material system provides effective photoprotection while eliminating the dry, white residue associated with inorganic filters, as the organic filters can be used at lower concentrations and the siloxane provides a smooth tactile feel.
3Stability of the object's composition
If traditional polymers are used to thicken and stabilize emulsions, then emulsion stability is improved, but compatibility deteriorates due to sensitivity to electrolytes from UV filters
Solution Approach 1:
The patent changes the chemical nature of the stabilizing agent from traditional water-soluble polymers to a crosslinked siloxane elastomer. This parameter change in the stabilizer's chemical structure (from hydrophilic polymer to amphiphilic siloxane) makes it compatible with electrolytes from liposoluble UV filters, as the crosslinked siloxane structure is not sensitive to ionic strength changes that affect traditional polymers.
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 a stable and aesthetically pleasing sunscreen with high SPF and broad-spectrum UV protection, maintaining integrity through multiple freeze/thaw cycles and temperature variations without separation or crystallization, while ensuring effective water-soluble ingredient penetration.
Implementation Method 1
a first emulsifier that is an emulsifying crosslinked siloxane elastomer... a phase ratio of the aqueous phase to the oil phase of about 1.0 to about 12.0
Implementation Method 2
an aqueous phase containing at least one stability boosting polyol at a concentration, by weight, of from about 10% to about 25%... stable and does not demonstrate crystallization or emulsion after 10 cycles of freeze/thaw
Implementation Method 3
The water-releasing effect enables the composition, initially in the form of an emulsion, to be converted into a plurality of droplets upon application of shear, such as, for example, rubbing
Implementation Method 4
an oil phase comprising... a combined organic UV filter comprising a liquid organic liposoluble UV filter and a solid organic liposoluble UV filter... sun protection factor (SPF) of greater than or equal to 15
Data Source
AI summary
A water-releasing sunscreen composition in the form of a stable, tactilely pleasing emulsion containing significant amounts of at least one liposoluble active ingredient is provided. The composition includes an aqueous phase containing at least one water-soluble ingredient. The composition further includes an oil phase containing a first emulsifier and a liquid organic liposoluble UV filter. The liquid organic liposoluble UV filter is at a concentration from about 10% to about 25%. The composition includes a phase ratio of the aqueous phase to the oil phase of about 1.0 to about 10.0. The sunscreen composition is stable, has a sun protection factor (SPF) of greater than or equal to 15 and converts from an emulsion to a plurality of droplets upon application of shear.