Multilayer Effect Pigment with Non-Quarter-Wave Optical Thickness
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Solution Overview
Problem
Commercially available effect pigments with a single high refractive index coating provide limited reflectivity, luster, chromaticity, and hiding power due to the requirement of quarter-wave stacks for interference colors, restricting the creation of desired hues and colors.
Innovation Solution
A multilayer effect pigment with a transparent substrate and alternating high and low refractive index layers, where the total number of layers is odd and at least one layer has a unique optical thickness, allowing for varied refractive index differences and non-quarter-wave stack configurations, enhancing luster, chromaticity, and hiding power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single high refractive index coating is applied to create effect pigment, then the manufacturing process is simple, but the luster, chromaticity and hiding power are limited
Solution Approach 1:
The single coating is segmented into multiple alternating layers of high and low refractive index materials. This segmentation creates multiple reflecting interfaces within the coating structure, enhancing light reflection and interference effects to improve luster and chromaticity while maintaining manufacturing feasibility through sequential deposition processes.
Solution Approach 2:
The coating is transformed from a single material layer to a composite structure with alternating high and low refractive index materials. This composite approach optimizes optical properties by leveraging the complementary characteristics of different materials to achieve superior luster, chromaticity and hiding power.
2Manufacturing precision
If quarter-wave stack structure is used to achieve interference colors, then each color requires unique layer thickness combination, but this increases manufacturing complexity and limits color variety
Solution Approach 1:
The patent changes the optical thickness parameters of the layers from strict quarter-wave multiples to non-quarter-wave values. By using optical thicknesses that are not equal to whole number multiples of one-quarter wavelength, the patent achieves interference colors without requiring unique thickness combinations for each color, thereby reducing manufacturing complexity while maintaining precise color control.
Solution Approach 2:
Instead of following the conventional quarter-wave stack approach where specific thickness ratios are mandatory, the patent inverts the logic by using non-quarter-wave thicknesses. This inversion allows for simplified manufacturing while still achieving the desired interference effects through alternative optical path length configurations.
3Illumination intensity
If multiple alternating layers are used to improve luster and chromaticity, then the hiding power improves, but the manufacturing process becomes more complex
Solution Approach 1:
The alternating layer structure is designed to serve multiple functions simultaneously: enhancing luster through increased light reflection, improving chromaticity through interference effects, and providing adequate hiding power through multiple interfaces. This multi-functionality is achieved within a manufacturable framework by using materials and deposition parameters that can be controlled with standard industrial equipment.
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 achieves improved luster, chromaticity, and hiding power without adhering to quarter-wave stack requirements, enabling a broader range of interference colors and angle-dependent reflectivity, making it suitable for various applications including automotive and industrial paints.
Implementation Method 1
These pigments exhibit pearl-like luster as a result of reflection and refraction of light
Implementation Method 2
These pigments exhibit pearl-like luster as a result of reflection and refraction of light
Implementation Method 3
depending on the thickness of the metal oxide layer, they can also exhibit interference color effects
Data Source
AI summary
A multilayer effect pigment includes a transparent substrate, a layer of high refractive index material on the substrate, and alternating layers of low refractive index and high refractive index materials on the first layer, the total number of layers being an odd number of at least three, all adjacent layers differing in refractive index by at least about 0.2 and at least one of the layers having an optical thickness which is different from all of the other layers. The resulting multilayer effect pigment is not a quarter-wave stack. The present effect pigments may be used in cosmetic and industrial applications.