Zinc Oxide Powder Dispersion Stability
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Solution Overview
Problem
Zinc oxide fine particles, despite their high transparency and ultraviolet-shielding properties, pose challenges due to high surface energy and agglomeration issues, making it difficult to achieve high solid content concentrations in dispersions and cosmetic materials, which limits their effectiveness and flexibility in formulations.
Innovation Solution
Zinc oxide powder with a specific surface area between 1.5 m^2/g and 65 m^2/g, conductivity of 150 µS/cm or less, and bulk specific volume between 0.5 mL/g and 10 mL/g, allowing for high solid content dispersions and improved dispersion stability, is used in conjunction with a dispersion medium and resin in paints and cosmetic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content of zinc oxide powder in the dispersion is increased to achieve high solid content concentration, then the ultraviolet-shielding function is improved, but the fluidity of the dispersion becomes low and it becomes difficult to sufficiently stir the dispersion
Solution Approach 1:
The patent changes the physical parameters of zinc oxide particles by controlling their primary particle diameter to 0.1 µm or less and specific surface area to 10 m²/g or more. This parameter change allows the particles to maintain high dispersion stability even at high solid content concentrations (50-90 mass%), resolving the contradiction between increasing zinc oxide content and maintaining fluidity. The fine particle size and high surface area enable effective stirring and uniform dispersion while achieving the desired high powder content.
2Illumination intensity
If the primary particle diameter of zinc oxide particles is decreased to achieve high transparency, then the transparency is improved, but the surface energy increases and the particles agglomerate together
Solution Approach 1:
The patent simultaneously optimizes two critical parameters: primary particle diameter (0.1 µm or less) and specific surface area (10 m²/g or more). This dual parameter control prevents agglomeration while maintaining transparency. The high specific surface area compensates for the high surface energy of fine particles through increased interaction with dispersion medium, stabilizing the dispersion and preventing agglomeration despite the small particle size required for transparency.
3Object-affected harmful factors
If the content of zinc oxide powder is increased to improve ultraviolet-shielding function, then the shielding function is improved, but the degree of freedom in formulation decreases and the number of functions that can be imparted is small
Solution Approach 1:
By changing the particle parameters (diameter ≤0.1 µm, specific surface area ≥10 m²/g), the patent enables high zinc oxide content (50-90 mass%) without compromising dispersion stability. This resolves the formulation constraint, allowing simultaneous incorporation of multiple functional components while maintaining high ultraviolet-shielding effectiveness. The improved dispersion stability provides flexibility to add other ingredients without causing agglomeration or instability.
Data Source
AI summary
Zinc oxide powder of the present invention has a specific surface area which is in a range of 1.5 m2/g to 65 m2/g, a conductivity which is 150 µS/cm or less and a bulk specific volume which is in a range of 0.5 mL/g to 10 mL/g.