Alumina Flake Effect Pigments with Metal Oxide Coatings
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Solution Overview
Problem
Existing Al2O3 flake-based effect pigments suffer from low chemical and weather stability, tendency to agglomerate, and a greyish color when used in cosmetic and paint compositions, limiting their application.
Innovation Solution
Alumina flakes coated with metal oxides at specific ratios (27:73 to 83:17) to enhance stability, prevent agglomeration, and achieve improved luster and color purity, using metal oxides like TiO2, Fe2O3, and SiO2, with precise layer thickness and distribution for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Al2O3 flakes are used as effect pigments, then pearlescent luster and metallic luster can be achieved, but chemical and weather stability is insufficient and greyish color masstone occurs
Solution Approach 1:
The patent applies composite materials by coating Al2O3 flakes with metal oxides (such as TiO2, Fe2O3, Cr2O3, ZnO, or mixtures thereof) to create a multi-layer structure. This composite approach combines the pearlescent properties of Al2O3 with the stability and color properties of metal oxide coatings, resolving the contradiction between achieving luster and maintaining weather stability.
2Adaptability or versatility
If Al2O3 flakes are incorporated into compositions, then effect pigment functionality is achieved, but tendency to agglomerate occurs
Solution Approach 1:
The patent applies local quality by providing a metal oxide coating on the surface of Al2O3 flakes. This coating modifies the surface properties locally, improving dispersibility and reducing agglomeration tendency while preserving the bulk optical properties needed for effect pigment functionality.
3Ease of manufacture
If zinc doped Al2O3 flakes are used, then pearlescent pigments can be produced, but stability under acidic conditions is poor
Solution Approach 1:
The patent applies parameter changes by replacing zinc doping with metal oxide coatings. This changes the chemical composition and surface properties of the Al2O3 flakes, providing resistance to acidic conditions while maintaining pearlescent pigment production capability.
4Illumination intensity
If effect pigments with high metal oxide coating are used, then chroma and color purity improve, but chemical stability decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the Al2O3 to metal oxide ratio within the range of 70:30 to 95:5. This precise control of composition parameters achieves the balance between improving chroma and color purity through metal oxide coating while maintaining chemical stability by limiting the total metal oxide content.
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 solution provides high chemical and weather stability, reduced agglomeration, enhanced optical properties, and improved color appearance, making them suitable for various applications including paints, coatings, and cosmetics.
Implementation Method 1
The effect pigments according to the invention show improved optical properties, in particular increased chroma, higher luster
Implementation Method 2
Imparting a pearlescent luster, metallic luster, color flop or multicolor effect can be achieved by using pearlescent pigments based on natural or synthetic transparent flakes
Data Source
AI summary
Effect pigments based on Al2O3 flakes with high weather resistance and less photoactivity and to their use thereof in paints, industrial coatings, automotive coatings, printing inks, cosmetic formulations. The effect pigments have a ratio of the amount by weight of Al2O3 of the Al2O3 flake and the amount by weight of the metal oxide(s) of the coating layer(s) in the range of from 27:73 to 83:17 based on the total weight of the effect pigment.