Oil-in-Water Emulsion Drop Size and Oil Content Optimization
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Solution Overview
Problem
Current cosmetic oil-in-water emulsions struggle to achieve a light, fluid texture with large drops that provide a freshness effect while maintaining a non-greasy and soft finish on the skin.
Innovation Solution
Combining 2-acrylamido-2-methylpropanesulfonic acid polymer, a copolymer of 2-acrylamido-2-methylpropanesulfonic acid and alcohol (meth)acrylate, and a hydrophobic-modified inulin-based amphiphilic polymer in an oil-in-water emulsion with mean drop sizes between 15 to 500 microns and an oily phase less than 35% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If giant drops (large drop size) are used in O/W emulsion, then soft and silky finish is improved, but texture becomes too thick and penetration into skin becomes excessively slow
Solution Approach 1:
The patent applies parameter changes by optimizing the drop size within a specific range (10-50 μm) rather than using larger giant drops, and by controlling the oily phase content (10-30%) to achieve the right balance between soft finish and penetration speed. The viscosity is also controlled (50-500 cP) to ensure proper application and absorption characteristics.
2Quantity of substance
If high oil content (>40%) is used in O/W emulsion, then emollience and softness are improved, but greasy and shiny effect occurs on skin
Solution Approach 1:
The patent changes the oil content parameter to an optimized range of 10-30%, which is lower than conventional giant-drop emulsions (>40%). This parameter change eliminates the greasy and shiny effect while maintaining emollience and softness through the selected oil phase components and their interaction with the amphiphilic polymer.
3Object-generated harmful factors
If low oil content (<30%) is used in O/W emulsion, then non-greasy effect and stability are improved, but sensory aspect and freshness effect become unsatisfactory
Solution Approach 1:
The patent uses a composite approach by combining a specific amphiphilic polymer (2-acrylamido-2-methylpropanesulfonic acid derivative with specific molecular weight and architecture) with a carefully selected oil phase and aqueous phase components. This composite formulation achieves both non-greasy effect and satisfactory sensory performance including freshness effect, which neither component alone could provide.
4Stability of the object's composition
If crosslinked polymers (e.g., Pemulen TR1® and TR2®) are used, then emulsion structure is stabilized, but drop size increases to 10-15 μm and creaming occurs in fluid textures
Solution Approach 1:
The patent extracts the crosslinking functionality from the polymer structure, using non-crosslinked 2-acrylamido-2-methylpropanesulfonic acid derivative instead. This removal of crosslinking prevents the formation of large gel networks that cause creaming, while still providing sufficient steric stabilization to maintain emulsion stability with smaller, more uniform drops.
Solution Approach 2:
The patent changes the polymer architecture parameter from crosslinked to non-crosslinked linear or branched structure, and optimizes the molecular weight (10^6 to 10^8 g/mol) to achieve the right balance between stabilization capability and fluidity, preventing creaming while maintaining emulsion stability.
Data Source
AI summary
The present invention relates to a cosmetic composition, in the form of an oil-in-water emulsion, characterized in that it comprises a 2-acrylamido-2-methylpropanesulfonic acid polymer, a copolymer of 2-acrylamido-2-methylpropanesulfonic acid and of an alcohol(meth)acrylate, and a hydrophobic-modified inulin-based amphiphilic polymer, the globules of the said emulsion having a mean size ranging from 15 to 500 microns and the oily phase being present in an amount of less than 35% by weight relative to the total weight of the composition. The invention also relates to a cosmetic process for treating keratin materials.