Hexagonal Plate-Shaped Zinc Oxide Particles with Iron Oxide for UV Shielding
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Solution Overview
Problem
Current ultraviolet shielding agents for cosmetics, particularly those targeting UV-A radiation, require high amounts of organic compounds and lack sufficient inorganic alternatives with improved UV-A and UV-B shielding performance, necessitating the development of more effective inorganic particles.
Innovation Solution
Zinc oxide particles with a hexagonal plate shape and a solid solution of Ti and/or Fe elements, forming Zn2TiO4 or ZnFe2O4 on their surface, which enhance UV shielding properties without compromising direct transition electronic excitation, are produced using specific methods involving aqueous solutions and baking processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic ultraviolet shielding agents such as zinc oxide and titanium oxide are used to shield UV-A radiation, then UV-A shielding performance is improved, but the amount of inorganic agents required increases significantly compared to organic agents
Solution Approach 1:
The patent creates a composite inorganic ultraviolet shielding agent by incorporating iron oxide particles into zinc oxide particles. This composite structure combines the UV shielding properties of zinc oxide with the enhanced UV-A absorption capabilities of iron oxide, achieving superior UV-A protection while reducing the total quantity of inorganic agents needed compared to using zinc oxide alone.
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where iron oxide is concentrated in specific regions (core or surface layers) of the zinc oxide particles. This localized distribution of iron oxide enhances UV-A absorption at critical wavelengths while maintaining the overall structure and properties of the zinc oxide particle, thereby improving shielding efficiency without requiring excessive amounts of inorganic material.
2Reliability
If iron oxide is added to zinc oxide particles to enhance UV-A absorption, then UV-A shielding ratio is improved, but visible light transparency may be compromised
Solution Approach 1:
The patent controls the local distribution of iron oxide within the zinc oxide particle structure, placing it in the core or as a surface coating rather than uniformly throughout. This localized approach allows the iron oxide to enhance UV-A absorption while minimizing its impact on visible light transmission, as the iron oxide concentration in the visible light path is reduced.
Solution Approach 2:
The patent carefully controls the particle size, iron oxide concentration, and structural configuration parameters to optimize the balance between UV-A absorption and visible light transparency. By adjusting these parameters, the patent achieves enhanced UV-A shielding while maintaining adequate visible light transmission for cosmetic applications.
3Ease of manufacture
If conventional zinc oxide particles are used, then production process is simple, but ultraviolet shielding performance for UV-A and UV-B is insufficient
Solution Approach 1:
The patent employs a relatively simple composite material formation process where iron oxide particles are incorporated into zinc oxide particles through co-precipitation or surface coating methods. This approach maintains ease of manufacture while significantly improving UV shielding performance, as the composite structure leverages the complementary properties of both materials without requiring complex multi-step synthesis.
Solution Approach 2:
The patent merges the production processes of zinc oxide and iron oxide into a single integrated process, creating composite particles that possess enhanced UV shielding capabilities. This combining approach simplifies manufacturing compared to producing separate particles and mixing them, while achieving superior UV-A and UV-B protection through the synergistic effect of both materials.
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 particles demonstrate significantly improved UV shielding ratios for both UV-A and UV-B radiation, offering enhanced protection while maintaining the direct transition properties and visible light transparency, making them suitable for cosmetic applications.
Implementation Method 1
zinc oxide can absorb effectively the light at the wavelength of 388 nm or less corresponding substantially to the Eg value
Implementation Method 2
electronic excitation thereof is direct transition so that zinc oxide can absorb effectively the light at the wavelength of 388 nm or less
Implementation Method 3
The scattering effect depends on the reflection factor of the particle and the particle size
Implementation Method 4
the light at the wavelength of about 320 nm or less being smaller than 413 nm corresponding to original Eg value can be absorbed effectively
Implementation Method 5
the electronic excitation of titanium oxide is indirect transition
Implementation Method 6
it is thought that iron oxide absorbs the light at the wavelength of 400 to 564 nm being a visible ray not only the UV-A radiation
Implementation Method 7
The Eg of iron oxide (hematite) is 2.2 eV, and the wavelength corresponding to the Eg is 564 nm
Data Source
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AI summary
It is one of the objects of the present disclosure to provide hexagonal plate-shaped zinc oxide particles having suitable performances derived from the shape thereof, that is, zinc oxide particles having improved ultraviolet shielding ratio at the wavelength of 400 nm or less without impairing the direct transition properties of electronic excitation thereof and having remarkably improved ultraviolet shielding ratio for UV-B radiation and UV-A radiation. A zinc oxide particle containing a solid solution of a Ti element and/or a Fe element and a Zn element in at least a portion thereof, and having a hexagonal plate shape.