Oil-in-Water Emulsion Surfactant System for Stable Phase Inversion
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Solution Overview
Problem
Existing cosmetic oil-in-water emulsions with polyglycerol esters and fatty polyacids suffer from rapid phase inversion during application on keratin materials, leading to unstable compositions and reduced 'playtime', making it difficult to achieve even deposition, especially with pigments.
Innovation Solution
A cosmetic composition comprising a lipophilic surfactant with HLB less than or equal to 9 and a specific anionic surfactant with sulfate and/or sulfonate functions, which undergoes phase inversion upon application, providing a stable and satisfactory duration of application, along with improved cosmetic properties such as freshness and reduced greasiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If existing surfactant combinations (polyglycerol esters with lauryl glucoside or disodium cetearyl sulfosuccinate) are used to achieve phase inversion on keratin materials, then the composition undergoes phase inversion during application, but the duration of application is reduced and stability is compromised
Solution Approach 1:
The patent changes the chemical parameters of the surfactant system by selecting specific anionic surfactants (sulfates or sulfonates with C12-C22 alkyl chains) combined with lipophilic surfactants (HLB ≤ 9) in controlled ratios (0.5:9.5 to 4:6). This parameter optimization resolves the contradiction by achieving both emulsion stability and satisfactory application duration (45-75 seconds) through precise compositional control
Solution Approach 2:
The patent creates a composite surfactant system combining specific anionic surfactants (sulfates/sulfonates) with lipophilic surfactants (polyglycerol esters, sorbitan esters, or sugar esters) in defined proportions. This composite approach enables the emulsion to maintain stability while achieving controlled phase inversion with optimal playtime, resolving the contradiction between stability and application duration
2Speed
If rapid phase inversion occurs during application to achieve quick lipophilic film formation, then the composition transforms quickly on skin, but the playtime is reduced making it difficult to spread evenly
Solution Approach 1:
The patent applies partial action by controlling the phase inversion process to occur at an optimal rate rather than maximally fast. The surfactant composition enables moderate phase inversion speed that provides 45-75 seconds of playtime, allowing sufficient time for even spreading while still achieving the desired lipophilic film formation on skin
Solution Approach 2:
By adjusting the HLB values and ratios of surfactants (anionic surfactant at 0.5-4 parts with lipophilic surfactant at 6-9.5 parts), the patent optimizes the phase inversion kinetics to achieve the right balance between inversion speed and operational time, resolving the contradiction between quick transformation and ease of spreading
3Stability of the object's composition
If conventional surfactant systems are used to achieve phase inversion, then the composition transforms on application, but the cosmetic properties such as freshness and greasiness feel are compromised
Solution Approach 1:
The patent optimizes the HLB parameters of the surfactant system (lipophilic surfactant with HLB ≤ 9 combined with anionic surfactant) to achieve phase inversion that produces desirable cosmetic properties. This parameter control ensures the inverted emulsion provides a fresh, light feel with reduced greasiness while maintaining stable phase inversion behavior
Solution Approach 2:
The composite surfactant system combines specific anionic surfactants (sulfates/sulfonates) with lipophilic surfactants in optimized ratios, creating a formulation that achieves both stable phase inversion and improved cosmetic feel. The synergistic interaction of these components resolves the contradiction between phase inversion stability and cosmetic acceptability
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 exhibits enhanced stability and a longer 'playtime' of 45-75 seconds, ensuring even deposition and improved cosmetic feel, while maintaining stability over time and after storage.
Implementation Method 1
the combination of at least one specific anionic surfactant comprising at least one sulfate and/or sulfonate function, and at least one lipophilic surfactant with an HLB of less than or equal to 9, produces a composition in the form of an oil-in-water emulsion that undergoes phase inversion when applied to keratin materials
Data Source
AI summary
The invention relates to a cosmetic composition in the form of an oil-in-water emulsion comprising: (i) at least one lipophilic surfactant with HLB less than or equal to 9, and (ii) at least one specific anionic surfactant comprising at least one sulfate and/or sulfonate function; said composition comprising from 0% to 8% by weight of additional surfactant(s) relative to the total weight of the composition. It also relates to the associated cosmetic process.