Hexagonal Plate Zinc Oxide Particles for UV Blocking and Slippage
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Solution Overview
Problem
Conventional zinc oxide particles with a hexagonal plate shape for cosmetics and heat releasing applications suffer from poor slippage, inconsistent physical properties, and require calcination, which alters particle diameter and shape, while existing solutions fail to provide stable, fine, and uniform particles with both soft focus effect and ultraviolet blocking performance.
Innovation Solution
Producing hexagonal plate-shaped zinc oxide particles with a primary particle diameter of 0.01 µm or more and an aspect ratio of 2.5 or more, achieved by aging zinc oxide fine particles in an aqueous zinc salt solution at specific concentrations and temperatures, avoiding calcination to maintain shape and size control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional zinc oxide ultrafine particles (0.1 µm or less) are used for ultraviolet blocking, then ultraviolet blocking performance is achieved, but slippage deteriorates and comfort in use is reduced
Solution Approach 1:
The invention changes the particle shape parameter from conventional spherical or irregular shapes to hexagonal plate shape with specific aspect ratio (2.5 or more) and controlled particle diameter (0.2 µm or less). This parameter change enables the particles to provide both ultraviolet blocking performance and improved slippage characteristics, resolving the contradiction between protection and comfort.
Solution Approach 2:
The invention creates a composite effect by combining the ultraviolet blocking properties of zinc oxide with the slippage-enhancing properties of plate-shaped particles. The hexagonal plate shape allows the particles to function both as UV blockers and as lubricating elements that improve cosmetic application and comfort.
2Ease of operation
If plate-shaped particles (talc, mica, barium sulfate) are used to improve slippage, then comfort in use is enhanced, but ultraviolet blocking effect is lost
Solution Approach 1:
The hexagonal plate-shaped zinc oxide particles serve multiple functions simultaneously: they provide ultraviolet blocking performance like conventional zinc oxide particles, while also providing slippage and comfort enhancement like plate-shaped fillers. This multi-functionality eliminates the need to choose between UV protection and comfort.
3Ease of operation
If zinc oxide fine particles or titanium oxide fine particles are used in small amounts to maintain slippage, then slippage is preserved, but additional organic ultraviolet blocking agents are required
Solution Approach 1:
The hexagonal plate-shaped zinc oxide particles replace the need for multiple ingredients by providing both UV blocking and slippage enhancement in a single component, simplifying the formulation while maintaining or improving performance.
4Ease of manufacture
If calcination is performed to produce zinc oxide particles, then zinc oxide is obtained, but particle diameter and shape are altered and controlled
Solution Approach 1:
The invention performs preliminary shaping of zinc oxide particles before calcination by controlling the precipitation conditions to form hexagonal plate-shaped precursors. This preliminary action ensures that the final calcined particles retain the desired hexagonal plate shape and size distribution, preventing the loss of shape control that normally occurs during high-temperature treatment.
Solution Approach 2:
The invention changes the precipitation parameters (pH, temperature, zinc salt concentration, aging time) to control the formation of hexagonal plate-shaped zinc oxide particles with specific aspect ratios. By optimizing these parameters, particles with consistent size and shape are obtained even without calcination, achieving manufacturing precision.
5Shape
If existing hexagonal plate-shaped zinc oxide particles are used, then some shape control is achieved, but particle diameter and shape significantly vary and aggregation occurs
Solution Approach 1:
The invention optimizes precipitation parameters including pH (8.5-10.5), temperature (20-100°C), zinc salt concentration (0.1-1.0 mol/L), and aging time (1-24 hours) to produce hexagonal plate-shaped particles with consistent size (0.2 µm or less) and shape (aspect ratio 2.5 or more). This precise parameter control eliminates the significant variation and aggregation problems of existing particles.
Solution Approach 2:
The invention implements quality control through measurement of particle size distribution and shape characteristics to ensure batch-to-batch consistency. By monitoring these parameters and adjusting precipitation conditions accordingly, stable and uniform hexagonal plate-shaped particles are produced without aggregation.
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 offer excellent comfort, soft focus effect, ultraviolet blocking performance, and heat releasing capabilities, with controlled particle diameter and shape ensuring stable cosmetic and thermal conductivity properties.
Implementation Method 1
a crystal growth step of causing zinc oxide fine particles to grow in an aqueous zinc salt solution
Implementation Method 2
a crystal growth step of causing zinc oxide fine particles to grow in an aqueous zinc salt solution
Data Source
Figure 1~3
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Figure 5~6
AI summary
An object of the present invention is to provide hexagonal plate-shaped zinc oxide particles which can be used as a cosmetic raw material, a heat releasing filler and the like, a method for production of the same, and a cosmetic, a heat releasing filler, a heat releasing resin composition, a heat releasing grease and a heat releasing coating composition each comprising the same. Provided are hexagonal plate-shaped zinc oxide particles having hexagonal-shaped surfaces, wherein the primary particle diameter is 0.01 µm or more and the aspect ratio is 2.5 or more, and 50% or more of 250 particles in a transmission electron microscope photograph satisfy both the requirements (1) and (2) : (1) the particle has a hexagonal-shaped surface; and (2) Dmin/Dmax ≥ 0.3, where Dmax: a length of the largest diagonal line of three diagonal lines of the hexagonal-shaped surface of the hexagonal plate-shaped zinc oxide particle; and Dmin: a length of the smallest diagonal line of three diagonal lines of the hexagonal-shaped surface of the hexagonal plate-shaped zinc oxide particle.