Surface-Treated Zinc Oxide Powder for Low Zinc Ion Elution
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Solution Overview
Problem
Zinc oxide powders exhibit high environmental toxicity due to zinc ion elution, which interacts with anionic water-based thickeners in cosmetics, leading to reduced viscosity and stability issues.
Innovation Solution
A method involving controlled neutralization, filtration, washing, and calcination of zinc oxide powders, followed by surface treatment with agents like silicone oil or aliphatic acids, reduces zinc ion elution to 0.2 ppm or less, and a composition combining these powders with specific water-based thickeners enhances stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zinc oxide is applied to aqueous cosmetic containing anionic water-based thickener, then zinc oxide provides UV protection and cosmetic functionality, but zinc ions elute from zinc oxide and interact with the thickener, causing viscosity reduction and stability deterioration
Solution Approach 1:
The patent applies a silane coating layer as an intermediary substance between zinc oxide particles and the aqueous cosmetic environment. This coating layer prevents direct contact between zinc ions and water-based thickeners, thereby eliminating the harmful interaction while maintaining cosmetic functionality. The silane coating acts as a barrier that reduces zinc ion elution without compromising the UV protection and cosmetic performance of zinc oxide.
Solution Approach 2:
The patent creates a composite structure by coating zinc oxide particles with silane compounds. This composite material combines the UV-blocking properties of zinc oxide with the stabilizing and low-elution characteristics of silane coating. The composite structure maintains the functional benefits of zinc oxide while significantly reducing zinc ion elution into the cosmetic formulation.
2Reliability
If zinc oxide powder is used in cosmetic formulations, then it provides sun protection and cosmetic benefits, but it causes environmental toxicity due to zinc ion elution in water
Solution Approach 1:
The silane coating serves as an intermediary barrier that prevents zinc ions from leaching into the environment while maintaining the cosmetic performance of zinc oxide. This coating layer significantly reduces zinc ion elution into water, thereby reducing environmental toxicity without compromising sun protection or cosmetic benefits.
Solution Approach 2:
The patent modifies the surface properties of zinc oxide particles by applying a silane coating, which changes the chemical parameters at the particle surface. This modification reduces the reactivity of zinc oxide with water, thereby decreasing zinc ion elution and environmental toxicity while preserving the functional properties needed for cosmetic applications.
3Reliability
If conventional zinc oxide powder is used, then it provides basic UV protection, but it causes significant viscosity reduction when combined with carbomer due to zinc ion elution
Solution Approach 1:
The silane coating acts as an intermediary layer that prevents zinc ions from interacting with carbomer molecules. This coating barrier eliminates the mechanism by which zinc ions would otherwise crosslink with carbomer and reduce viscosity, thereby maintaining stable viscosity in cosmetic formulations containing both zinc oxide and carbomer.
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 resulting zinc oxide powders and compositions exhibit significantly reduced zinc ion elution, maintaining stability and viscosity over time, reducing environmental impact and improving cosmetic and paint formulations.
Implementation Method 1
a first neutralization step of adding at least one alkali source selected from the group consisting of sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, sodium hydrogen carbonate and ammonium hydrogen carbonate to at least one zinc source selected from the group consisting of zinc chloride, zinc sulfate, zinc acetate and zinc nitrate
Implementation Method 2
a step of calcination at 200 to 1000 °C
Implementation Method 3
the zinc oxide powder is surface-treated with at least one surface treating agent selected from the group consisting of a silicone oil, an aliphatic acid, an alkylsilane and a hydrous silica
Data Source
AI summary
There is provided a zinc oxide powder wherein when 5 g of the zinc oxide powder is added to 70 g of ion exchange water and the mixture is stirred, a concentration of zinc ions eluting in the water is 0.2 ppm or less. Thus, there are provided a zinc oxide powder and a surface-treated zinc oxide powder for which a concentration of zinc ions eluting in water is reduced to a specific level or less; and a composition that can reduce an environmental load and has excellent stability over time.