Multi-layered Coating for Insulation Glazing Color Stability
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Solution Overview
Problem
Conventional transparent substrates with multiple metallic layers suffer from greenish/yellowish transmission colors, significant color change with angle, and imbalanced reflectance characteristics, which affect aesthetic and functional performance.
Innovation Solution
A multi-layered coating structure is applied to the transparent substrate, comprising specific dielectric and metallic layers with optimized thickness ratios and an absorption layer, to achieve balanced characteristics including reduced greenish/yellowish color, minimal angle-dependent color change, and low coated surface reflectance while maintaining high uncoated surface reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the metallic layer is increased to achieve high reflectance and low emissivity, then the insulation effect is improved, but the transmission color becomes greenish/yellowish and the absorptance increases
Solution Approach 1:
The single metallic layer is segmented into multiple metallic layers (first metallic layer and second metallic layer) separated by dielectric layers. This segmentation allows each metallic layer to contribute to reflectance and emissivity control while the dielectric layers manage optical interference, preventing the greenish/yellowish color that occurs with a single thick metallic layer.
Solution Approach 2:
The patent uses a composite structure combining metallic layers (for reflectance and low emissivity) with dielectric layers (for optical interference control). This composite material approach enables simultaneous achievement of high insulation effect and neutral transmission color by leveraging the complementary properties of different materials.
2Loss of energy
If two or more metallic layers are used to achieve low emissivity and high selectivity, then the insulation performance is improved, but the color change depending on viewing angle increases significantly
Solution Approach 1:
Different layers in the coating are assigned different local qualities: metallic layers provide reflectance and low emissivity, while dielectric layers provide optical interference control. The specific refractive indices and thicknesses of dielectric layers are optimized to compensate for angle-dependent color changes, creating local optical compensation zones that stabilize the overall appearance.
Solution Approach 2:
The patent optimizes specific parameters including the refractive indices, thicknesses, and material compositions of dielectric layers to counteract the angle-dependent color changes inherent in multi-metallic layer structures. By carefully controlling these parameters, the color coordinate variation with viewing angle is minimized while maintaining low emissivity.
3Loss of energy
If the external reflectance is increased to achieve high uncoated surface reflectance, then the insulation effect is improved, but the coated surface reflectance also increases which affects visibility
Solution Approach 1:
Dielectric layers serve as intermediaries between the metallic layers and the external environment. These dielectric layers have optimized refractive indices that mediate the optical interaction, allowing high uncoated surface reflectance for insulation while controlling coated surface reflectance to maintain visibility. The dielectric layers act as optical buffers that decouple the reflectance function from the visibility function.
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 results in a transparent substrate with improved color stability, reduced angle-dependent color change, and enhanced reflectance balance, maximizing insulation and visibility while minimizing heat transfer.
Implementation Method 1
The double-metallic layered substrate has more internal optical interferences, and thus, has a larger reflection color change depending on the angle
Implementation Method 2
when the thickness of the metallic layer is increased, a blue color is absorbed so that a transmission color or reflection color may be closer to a green-based color
Implementation Method 3
A low-emissivity glass is a glass on which a low-emissivity layer including a metal having high reflectance in an infrared region such as silver (Ag) is deposited as a thin film
Data Source
Figure 1~4
Figure 5
AI summary
A transparent substrate provided with a multi-layered coating is provided, the coating including the following in an order from the substrate: a first dielectric film including one or more dielectric layers, a first metal protective layer, a first metalic layer having an infrared (IR) reflection characteristic, a second metal protective layer, a second dielectric film including two or more dielectric layers, a third metal protective layer, a second metalic layer having an infrared (IR) reflection characteristic, a fourth metal protective layer, and a third dielectric film D3 including one or more dielectric layers, wherein the dielectric layer includes a metal oxide, a metal nitride, or a metal oxynitride, the metalic layer is silver (Ag) or a silver (Ag)-containing metal alloy, a normal emissivity is 2.0 % or less, and a difference between a coated surface reflectance and an uncoated surface reflectance is 21 % or more.