Interference Pigment Multilayer Structure for High Color Intensity
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Solution Overview
Problem
Existing interference pigments suffer from low color intensity and angle-dependent interference colors, making them unsuitable for various industrial applications, and are difficult to prepare or recover due to limitations in light transmission and compatibility with absorption pigments.
Innovation Solution
A method involving a platelet-shaped substrate coated with a lower Fe2O3 layer, a middle MgO·SiO2 layer, and an upper Fe2O3 layer, which provides a structure of alternating refractive indices to enhance color intensity and stability, using a process involving slurry preparation, hydrolysis, and calcination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single high refractive index metal oxide layer (e.g., TiO2) is coated on mica platelets to create interference pigment, then the pigment exhibits specific interference color, but the color saturation deteriorates and the color becomes fainter at tilted viewing angles
Solution Approach 1:
The patent divides the single metal oxide layer into multiple alternating layers of high refractive index material (TiO2, Fe2O3) and low refractive index material (SiO2, MgO). This segmentation creates a multilayer structure where each layer contributes to the overall interference effect, enhancing color intensity while reducing viewing angle dependence through constructive interference across multiple interfaces
Solution Approach 2:
The patent uses composite material structure by combining multiple metal oxide materials with different refractive indices (TiO2 with n=2.6, Fe2O3 with n=2.9, SiO2 with n=1.46, MgO with n=1.73) in alternating layers. This composite approach creates optimized optical interference patterns that maintain high color saturation across various viewing angles
2Illumination intensity
If opaque metal layers and alternate SiO2 and TiO2 layers are used to create gloss pigment, then interference color is achieved, but light transmission is blocked and compatibility with absorption pigments is extremely limited
Solution Approach 1:
The patent optimizes the thickness parameters of each layer in the multistack structure to control light transmission and interference effects. By carefully adjusting layer thicknesses, the pigment achieves high color intensity while maintaining sufficient light transmission for compatibility with absorption pigments in coating formulations
Solution Approach 2:
The patent introduces low refractive index layers (SiO2, MgO) as intermediary layers between high refractive index metal oxide layers. These intermediary layers serve as optical mediators that enhance interference effects while controlling overall light transmission, enabling better compatibility with absorption pigments
3Illumination intensity
If existing multilayer pigment structures are used, then interference color is achieved, but the pigments are difficult to prepare or recover
Solution Approach 1:
The patent employs a sol-gel process where metal alkoxides undergo self-assembly and hydrolysis to form oxide layers automatically. This self-service mechanism simplifies the manufacturing process by eliminating complex deposition equipment and enables easier recovery of pigments through standard filtration and drying procedures
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 interference pigment exhibits high chroma and color intensity, suitable for diverse applications such as paints, inks, and cosmetics, with improved productivity and ease of preparation compared to existing methods.
Implementation Method 1
refluxing the slurry to hydrolyze a metal salt of the FeCl3 solution
Implementation Method 2
refluxing the slurry to hydrolyze a metal salt of the MgO·SiO2 solution
Implementation Method 3
interference pigment having high color intensity using a difference between indexes of refraction of multiple metal oxide layers
Data Source
Figure 1
Figure 2
AI summary
The interference pigment with high color intensity includes: a platelet-shaped substrate including at least one of natural mica, synthetic mica, alumina flakes, glass flakes, and iron oxide flakes; a lower first metal oxide layer formed of Fe2O3 on the platelet-shaped substrate; a second metal oxide layer formed of MgO·SiO2 on the lower first metal oxide layer; and an upper first metal oxide layer formed of Fe2O3 on the second metal oxide layer.