O/W Emulsion Composition with Block Polymer Stabilizer
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Solution Overview
Problem
Existing O/W emulsion compositions face challenges in achieving high UV protection while maintaining formulation stability and a non-sticky, fresh feeling, often requiring high amounts of surfactants which lead to an oily sensation, and compounds like 4-t-butyl-4'-methoxydibenzoylmethane are difficult to dissolve and prone to precipitation.
Innovation Solution
The composition includes octocrylene, ethylhexyl methoxycinnamate, and 4-t-butyl-4'-methoxydibenzoylmethane dissolved in an oil phase with a specific polyoxyethylene/polyoxyalkylene alkyl ether block polymer, achieving emulsion particle sizes of 800 nm or less, which enhances UV protection, stability, and skin feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
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 and frictional or powdery feeling is caused
Solution Approach 1:
The patent changes the physical state parameter of UV absorbers from crystalline solid (4-t-butyl-4'-methoxydibenzoylmethane) to dissolved state in oil phase by controlling temperature and composition. This parameter change allows the UV absorber to be incorporated without causing whitish finish or powdery feeling while maintaining high UV protection ability.
Solution Approach 2:
The patent uses a composite oil phase system combining multiple UV absorbers (octocrylene, ethylhexyl methoxycinnamate, and 4-t-butyl-4'-methoxydibenzoylmethane) with specific emulsifiers. This composite material approach enables synergistic UV protection while preventing precipitation and maintaining cosmetic appearance.
2Object-affected harmful factors
If many organic UV absorbers such as octocrylene and ethylhexyl methoxycinnamate are used to provide high UV protection ability, then UV protection ability is improved, but stickiness increases and emulsion stability decreases
Solution Approach 1:
The patent employs a composite emulsion system combining specific ratios of organic UV absorbers with polyoxyethylene/polyoxypropylene alkyl ether block polymers as emulsifiers. This composite approach balances UV protection capability with emulsion stability by selecting compatible materials that work synergistically.
Solution Approach 2:
The patent optimizes the concentration parameters of UV absorbers and emulsifiers to achieve the desired balance. By controlling the amount of each component within specific ranges, the patent maintains both high UV protection and adequate emulsion stability without excessive stickiness.
3Object-affected harmful factors
If 4-t-butyl-4'-methoxydibenzoylmethane is incorporated by dissolving in an oil phase to achieve high UV absorption ability, then UV absorption ability is improved, but the compound is not easily dissolved and precipitates over time
Solution Approach 1:
The patent changes the temperature parameter during processing to facilitate dissolution of 4-t-butyl-4'-methoxydibenzoylmethane in the oil phase, then maintains appropriate storage conditions to prevent precipitation. This parameter control ensures both high UV absorption and long-term stability.
Solution Approach 2:
The patent uses other oil-soluble UV absorbers (octocrylene and ethylhexyl methoxycinnamate) as intermediaries to help dissolve and stabilize 4-t-butyl-4'-methoxydibenzoylmethane in the oil phase. These intermediary substances improve the solubility and prevent precipitation of the less soluble compound.
4Stability of the object's composition
If a large amount of surfactants is incorporated to achieve emulsion stability, then emulsion stability is improved, but an oily feeling in use is caused
Solution Approach 1:
The patent changes the molecular structure parameters of the emulsifier by selecting polyoxyethylene/polyoxypropylene alkyl ether block polymers with specific chain lengths and ether group ratios. This parameter optimization provides adequate emulsion stability with minimal oily feeling, as these polymers form stable emulsions at lower concentrations compared to traditional surfactants.
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 allows for a high UV protection ability across a wide range, excellent formulation stability, and a non-sticky, fresh skin feel, even with large amounts of organic UV absorbers, making it suitable for sunscreen cosmetics.
Implementation Method 1
a polyoxyethylene/polyoxyalkylene alkyl ether block polymer which serves as an emulsifier
Implementation Method 2
allowing the oil phase to have a certain emulsion particle size or less with use of a specific emulsifier
Implementation Method 3
UV protection ability has been often provided by incorporating organic UV absorbers... UV absorption ability in the region extending from UV-A to UV-B
Data Source
AI summary
The present invention provides an O/W emulsion composition which is excellent in UV protection ability, formulation stability, and feeling in use. The O/W emulsion composition according to the present invention is characterized by comprising the following components (a) and (b): (a) organic UV absorbers comprising the following components (a1), (a2), and (a3): (a1) octocrylene, (a2) ethylhexyl methoxycinnamate, (a3) 4-t-butyl-4'-methoxydibenzoylmethane; and (b) a polyoxyethylene/polyoxyalkylene alkyl ether block polymer represented by the following formula (1) or (2); (Compound 1) 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, 4≤m<70, 10≤n<70, and m< n; (Compound 2) 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 0.5<(q/(p + q))<0.8, and wherein average particle size of the emulsion particles comprising the component (a) is 800 nm or less.