Oil-in-Water Emulsion UV Absorber Ratio for Stability
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Solution Overview
Problem
Existing oil-in-water emulsion sunscreen cosmetics face issues with discoloration, poor spreadability, stickiness, and long-term stability due to the use of high amounts of ultraviolet absorbers and metal oxide powders, which also reduce their ultraviolet protective effectiveness.
Innovation Solution
An oil-in-water emulsified cosmetic composition comprising specific solid organic ultraviolet absorbers, hydrophobized fine particle metal oxide powders, and a polyacrylamide compound, with a controlled mass ratio and content of liquid organic ultraviolet absorbers and hydrophobized fine particle metal oxide powders, to enhance ultraviolet protection and stability while maintaining a good skin feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultraviolet absorbers are added in a large amount to enhance ultraviolet protective effect, then ultraviolet protection is improved, but discoloration occurs and feeling upon use deteriorates (poor spreadability and stickiness)
Solution Approach 1:
The patent changes the physical state parameter of the ultraviolet absorber from solid to liquid, and optimizes the concentration parameter to 8-20% by mass. This parameter transformation allows the liquid organic ultraviolet absorber to provide sufficient UV protection while maintaining good spreadability and preventing discoloration that occurs with solid absorbers used in higher concentrations.
Solution Approach 2:
The patent creates a composite emulsion system combining liquid organic ultraviolet absorbers with inorganic metal oxide powders (titanium dioxide and/or zinc oxide) in an oil-in-water emulsion matrix. This composite approach allows the liquid organic absorber to provide UV absorption while the emulsion system maintains stability and prevents the discoloration and aggregation problems associated with using either component alone in high amounts.
2Reliability
If metal oxide powder is added in a large amount to enhance ultraviolet protective effect, then ultraviolet protection is improved, but powder aggregation, sedimentation, and long-term stability decrease (decreased viscosity, emulsion separation, and precipitation)
Solution Approach 1:
The patent optimizes the particle size parameter of metal oxide powder to 0.1-1 μm average diameter and controls the content to 5-20% by mass. This parameter optimization prevents powder aggregation and sedimentation while maintaining sufficient UV protection. The fine particle size increases surface area for UV absorption while the controlled content level prevents emulsion instability.
Solution Approach 2:
The patent combines metal oxide powders with liquid organic ultraviolet absorbers in an emulsion system, creating a composite where the liquid phase disperses the solid powder particles uniformly. This composite structure prevents powder aggregation and sedimentation while providing synergistic UV protection from both inorganic and organic absorbers.
3Reliability
If both ultraviolet absorbers and metal oxide powder are used in combination to enhance ultraviolet protective effect, then ultraviolet protection is improved, but discoloration and long-term stability problems are more likely to occur
Solution Approach 1:
The patent creates a composite emulsion system integrating liquid organic ultraviolet absorbers (8-20% by mass) with inorganic metal oxide powders (5-20% by mass) in an oil-in-water emulsion matrix. This composite structure allows both components to work synergistically for UV protection while the emulsion system prevents discoloration and aggregation. The liquid organic absorber prevents the powder from aggregating, and the powder provides stable UV protection without the discoloration issues of solid organic absorbers.
Solution Approach 2:
The patent transforms the organic ultraviolet absorber from solid to liquid state and optimizes the concentration parameters of both organic and inorganic components. The liquid state of the organic absorber enables better compatibility with the emulsion system, preventing discoloration when combined with metal oxide powders, while the optimized content ratios ensure long-term 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
The composition achieves excellent long-term stability, high ultraviolet protective effectiveness, smooth spreadability, controlled stickiness, and improved waterproofness and perspiration resistance, providing a superior sunscreen experience.
Implementation Method 1
ultraviolet absorbers and metal oxide powders such as zinc oxide and titanium dioxide have been used in these oil-in-water emulsion cosmetics
Implementation Method 2
metal oxide powders such as zinc oxide and titanium dioxide have been used in these oil-in-water emulsion cosmetics
Implementation Method 3
An oil-in-water emulsified cosmetic composition comprising specific solid organic ultraviolet absorbers, hydrophobized fine particle metal oxide powders, and a polyacrylamide compound
Data Source
Figure 1~2
Figure 3
AI summary
Excellent long-term stability and a high ultraviolet protective effect are obtained. Further, provided is an oil-in-water emulsified cosmetic composition which has a good feeling upon use with smooth spreadability on the skin and controlled sticky feeling when applied, and extremely good waterproofness and perspiration resistance. The oil-in-water emulsified cosmetic composition comprising the following components (A) to (D), and satisfying the following conditions (i) and (ii): [Components] (A) a specific solid organic ultraviolet absorber, (B) 8% by mass or more and 20% by mass or less of a liquid oil, (C) a polyacrylamide compound, and (D) a hydrophobized fine particle metal oxide powder; [Conditions] (i) a total content of the component (A) and the component (D) ((A) + (D)) relative to a total amount of the cosmetic composition is 10% by mass or more, and (ii) a content mass ratio of the total content of the component (A) and the component (D) ((A) + (D)) relative to the total amount of the liquid oil (component(B)) is 0.6 or more and 2 or less.