O/W Emulsion UV Absorber Phase Segmentation
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Solution Overview
Problem
Existing oil-in-water (O/W) emulsified compositions face challenges in achieving high UV protection ability, formulation stability, and a non-sticky, refreshing feel, particularly when using organic UV absorbers like octocrylene and methylene bis-benzotriazolyl tetramethylbutylphenol, which tend to precipitate or cause a rough feeling due to aggregation.
Innovation Solution
The composition incorporates octocrylene and bis-ethylhexyloxyphenol methoxyphenyl triazine in the oil phase with a specific polyoxyethylene/polyoxyalkylene alkyl ether block polymer as an emulsifier, ensuring the oil phase has an average particle size of 700 nm or less, and methylene bis-benzotriazolyl tetramethylbutylphenol is dispersed in the aqueous phase, preventing aggregation and maintaining stability and feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of inorganic UV shielding powder such as fine particle titanium oxide and fine particle zinc oxide is incorporated to provide high UV protection ability, then UV protection ability is improved, but the finish becomes whitish or frictional or powdery feeling is caused
Solution Approach 1:
The patent changes the physical state parameters of UV absorbers by using oil-soluble UV absorbers in an oil phase and water-soluble UV absorbers in an aqueous phase, eliminating the need for inorganic powders and their associated cosmetic defects while maintaining UV protection
Solution Approach 2:
The patent introduces emulsifiers and solvents as intermediary substances to dissolve and disperse UV absorbers in appropriate phases (oil or water), enabling the UV absorbers to function effectively without requiring inorganic powder carriers
2Reliability
If highly polar organic UV absorbers such as octocrylene and ethylhexyl methoxycinnamate are used to provide excellent UV protection ability, then UV protection ability is improved, but stickiness increases and emulsion stability decreases
Solution Approach 1:
The patent segments the formulation into distinct oil and water phases, placing highly polar UV absorbers in the oil phase and water-soluble UV absorbers in the aqueous phase. This segmentation isolates the stickiness-causing components to the oil phase where they can be managed by the emulsion structure, while the aqueous phase provides a refreshing, non-sticky feel
Solution Approach 2:
The patent creates a composite emulsion system combining oil-soluble UV absorbers in the oil phase with water-soluble UV absorbers in the aqueous phase. This composite structure allows the benefits of highly polar UV absorbers (excellent UV protection) while mitigating their drawbacks (stickiness) through phase separation and the refreshing feel of the water phase
3Reliability
If bis-ethylhexyloxyphenol methoxyphenyl triazine is dissolved in the oil phase to prepare an O/W emulsified composition, then UV protection ability is improved, but the crystalline solid precipitates over time
Solution Approach 1:
The patent changes the solubility parameters by selecting UV absorbers with appropriate solubility characteristics for each phase: oil-soluble UV absorbers for the oil phase and water-soluble UV absorbers for the aqueous phase. This parameter matching prevents precipitation and maintains long-term stability
Solution Approach 2:
The patent introduces emulsifiers and co-solvents as intermediary substances that enhance the solubility of UV absorbers in their respective phases, preventing crystallization and precipitation over time while maintaining the desired UV protection ability
4Reliability
If fine particle powder of methylene bis-benzotriazolyl tetramethylbutylphenol is dispersed in the aqueous phase, then UV protection ability is improved, but the fine particle powder coarsens (agglutinates) over time causing decreased UV protection ability or rough feeling
Solution Approach 1:
The patent changes the solubility parameter by using water-soluble UV absorbers in the aqueous phase instead of insoluble fine particle powders. This parameter change enables molecular-level dissolution rather than particle suspension, preventing agglutination and maintaining stable dispersion
Solution Approach 2:
The patent introduces water-solubilizing agents or surfactants as intermediaries that enable UV absorbers to dissolve uniformly in the aqueous phase, preventing particle aggregation and maintaining long-term dispersion stability
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
This approach results in an O/W emulsified composition with enhanced UV protection, stability, and a non-sticky, refreshing feel, suitable for sunscreen cosmetics, capable of containing a large amount of organic UV absorbers without compromising performance over time.
Implementation Method 1
an O/W emulsified composition which contains an organic UV absorber in an oil state at ordinary temperature together with an organic UV absorber in a solid state at ordinary temperature
Implementation Method 2
a polyoxyethylene/polyoxyalkylene alkyl ether block polymer as an emulsifier
Implementation Method 3
UV protection ability has been often provided by incorporating organic UV absorbers or inorganic UV scatterers
Data Source
AI summary
The present invention provides an O/W emulsified composition which contains an organic UV absorber in an oil state such as octocrylene and a solid organic UV absorber, and is excellent in UV protection ability, formulation stability, and feeling in use. The composition according to the present invention is an O/W emulsified composition, comprising: (a) an organic UV absorber in an oil state at 20°C, comprising (a1) octocrylene; (b) an organic UV absorber in a solid state at 20°C, selected from (b1) bis-ethylhexyloxyphenol methoxyphenyl triazine and (b2) methylene bis-benzotriazolyl tetramethylbutylphenol; and (c) a polyoxyethylene/polyoxyalkylene alkyl ether block polymer represented by formula (1) or (2): R1O-(PO)m-(EO)n-H (1) wherein R1 is a hydrocarbon group having 16 to 18 carbon atoms; PO is an oxypropylene group, EO is an oxyethylene group, and PO and EO are added to each other in block form; and m and n respectively represent average addition mole number of PO and EO, 70>m>4, 70>n>10, and n>m; R2O-(AO)p-(EO)q-R3 (2) wherein R2 and R3 are either identical to or different from each other, and each of them is a hydrocarbon group having 1 to 4 carbon atoms; AO is an oxyalkylene group having 3 to 4 carbon atoms, EO is an oxyethylene group, and AO and EO are added to each other in block form; and p and q respectively represent average addition mole number of AO and EO, 1≤p≤70, 1 ≤q≤70, and 0.2<(q/(p + q))<0.8, and wherein average particle size of the oil phase comprising the component (a) is 700 nm or less.