Alpha-Fe2O3 Coated SiO2 Interference Pigments for Stable Red Hue
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing interference pigments based on SiO2 flakes coated with metal oxides exhibit a strong orange-red color effect at steep viewing angles, which combines interference and absorption colors, leading to orange or dark-brown down-flop at flat angles, and lack high hiding power and vegan compatibility.
Innovation Solution
SiO2 flakes coated with alpha-Fe2O3 crystallites of defined size, providing a pure bluish-red hue at all viewing angles with low angle dependence, high hiding power, and suitable for vegan applications, achieved through controlled nucleation and calcination processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If SiO2 flakes are coated with metal oxide layers to create interference pigments, then interference color effect is achieved, but the color shows strong orange-red at steep angles and orange or dark-brown down-flop at flat angles
Solution Approach 1:
The patent changes the chemical composition parameter by using alpha-Fe2O3 crystallites instead of conventional metal oxide layers, and controls the crystallite size parameter (0.5-5 μm) to achieve a bluish-red absorption color that compensates for the interference color at flat viewing angles, eliminating the orange-red down-flop effect
Solution Approach 2:
The patent creates a composite structure by coating SiO2 flakes with alpha-Fe2O3 crystallites, combining the interference properties of the flake structure with the absorption properties of the hematite crystallites to achieve a stable bluish-red hue across all viewing angles
2Illumination intensity
If conventional metal oxide coatings are used on SiO2 flakes, then interference color is produced, but hiding power is insufficient
Solution Approach 1:
The composite of SiO2 flakes coated with alpha-Fe2O3 crystallites provides both interference color and high hiding power, as the hematite coating layer contributes to light absorption and opacity while maintaining the interference effect
3Illumination intensity
If traditional pigments are used to achieve red color, then color saturation is achieved, but vegan compatibility is not satisfied
Solution Approach 1:
The patent replaces animal-derived carmine red pigments with synthetic alpha-Fe2O3 (hematite) crystallites, which are vegan-compatible inorganic materials that provide comparable or superior color saturation and stability without ethical concerns
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 interference pigments maintain a bright bluish-red absorption color across all angles, offer high chromaticity and hiding power, and are suitable for various applications including cosmetics and paints, while being temperature-stable and compatible with vegan formulations.
Implementation Method 1
bright bluish-red absorption colour
Implementation Method 2
bluish-red interference colour
Data Source
AI summary
Interference pigments based on SiO2 flakes coated with crystallites of alpha-Fe2O3. Also, a process for the preparation of interference pigments that comprise SiO2 flakes coated with a crystallite of alpha-Fe2O3, by a wet-chemical process in a fluidised bed, by a CVD process, by a PVD process, or by any combination of said processes. Also, the use of interference pigments based on SiO2 flakes coated with crystallites of alpha-Fe2O3, in particular in paints, coatings, industrial and automobile paints, ceramic materials, plastics and cosmetic formulations.