Spherical Zinc Oxide Particles with Plate-like Structure
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Solution Overview
Problem
Conventional zinc oxide particles for cosmetics lack a combination of good slippage, soft focus effect, and UV blocking properties, and existing spherical zinc oxide particles do not consist of integrated plate-like particles, which are necessary for achieving these properties.
Innovation Solution
Producing spherical zinc oxide particles consisting of integrated plate-like particles with a median size of 0.01 µm or more and a D90/D10 particle size distribution of 5.0 or less, using a method involving the neutralization of a zinc salt aqueous solution with an alkali aqueous solution in the presence of a hydrophilic nonionic dispersant, which enhances their friction coefficient and thermal conductive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ultrafine zinc oxide particles (100 nm or less) are used for UV blocking, then ultraviolet blocking performance is improved, but slippage deteriorates
Solution Approach 1:
The zinc oxide particles are segmented into multiple plate-like primary particles (5-50 nm thickness) that aggregate to form spherical composite particles (0.1-2.0 μm diameter). This segmentation allows the internal plate-like structure to provide slippage while the spherical external shape maintains UV blocking performance.
Solution Approach 2:
The invention creates a composite particle structure where multiple plate-like zinc oxide particles are aggregated and sintered together to form a spherical particle. The composite structure combines the UV blocking properties of zinc oxide with the slippage characteristics of plate-like morphology.
2Ease of operation
If plate-shaped particles (talc, mica, barium sulfate) are added to provide slippage, then slippage is improved, but ultraviolet blocking effect is reduced
Solution Approach 1:
The spherical zinc oxide particles perform multiple functions simultaneously: the plate-like internal structure provides slippage like talc or mica, while the zinc oxide composition and spherical external shape provide UV blocking. This eliminates the need to combine separate slippage agents and UV blockers.
3Manufacturing precision
If zinc oxide particles with sharp particle size distribution are produced, then manufacturing precision is improved, but particle shape control becomes more difficult
Solution Approach 1:
The invention performs preliminary action by controlling the neutralization reaction conditions (pH 6-8, specific Zn(OH)2 to Zn element ratio) and adding dispersants before particle formation to guide the growth of plate-like primary particles. This preliminary control ensures both sharp size distribution and correct plate-like spherical morphology.
Solution Approach 2:
The invention controls particle formation by changing key parameters: maintaining pH 6-8 during neutralization, controlling the Zn(OH)2 to Zn element ratio at 1.05-1.20, and using dispersants with specific HLB values (3-13). These parameter changes simultaneously achieve sharp size distribution and correct spherical plate-like structure.
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 particles provide excellent slippage, soft focus effect, and UV blocking performance, making them suitable for cosmetic applications and as a thermal conductive filler, with improved handling and antibacterial properties.
Implementation Method 1
neutralizing a zinc salt aqueous solution by an alkali aqueous solution in the presence of a hydrophilic nonionic dispersant
Implementation Method 2
neutralizing a zinc salt aqueous solution by an alkali aqueous solution
Data Source
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AI summary
It is an object of the present disclosure to provide spherical zinc oxide particles consisting of integrated plate-like particles which can be used as a cosmetic raw material, a thermal conductive filler and the like, and a method for production of the same. Spherical zinc oxide particles consisting of integrated plate-like particles, which have a median size of 0.01 µm or more and a D90/D10 in particle size distribution of 5.0 or less.