Colored laminate for radiative cooling and radiative cooling material including the same
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Solution Overview
Problem
Existing radiative cooling materials face challenges such as low ultraviolet-ray reflectance, insufficient infrared emissivity, and short lifespan due to degradation from UV light, moisture, and oxidation, which hinder efficient radiative cooling performance.
Innovation Solution
A colored laminate for radiative cooling is developed, comprising a colored layer with a first thermoplastic resin, a first light reflecting layer with high reflectance for near-infrared light, a second light reflecting layer with a metal layer protected by metal oxide layers, an adhesive layer, and an infrared-ray radiating layer, which collectively enhance visible and infrared light reflectance and infrared radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer material is used for radiative cooling, then infrared emissivity is high, but lifespan is short due to deterioration from ultraviolet light and moisture
Solution Approach 1:
The patent divides the cooling material into multiple functional layers: a polymer layer for infrared emissivity and a separate protective layer for UV and moisture resistance. This segmentation allows each layer to specialize in one function, resolving the contradiction between high infrared emissivity and long lifespan.
Solution Approach 2:
The patent creates a composite structure combining polymer material with protective coating materials. The composite maintains the polymer's high infrared emissivity while adding UV and moisture resistance, thereby extending lifespan without sacrificing radiative cooling performance.
2Reliability
If multi-layer thin film is used to increase infrared emissivity, then radiative cooling efficiency improves, but absorptivity of sunlight increases making it difficult to achieve high-efficiency cooling
Solution Approach 1:
The patent applies local quality by making each layer optically selective: the polymer layer is optimized for infrared emissivity while the protective layer is optimized for UV reflection and visible light transmission. This local optimization allows high infrared emissivity without increasing overall sunlight absorptivity.
3Reliability
If metal reflective layer is used, then radiative cooling performance improves, but long-term stability decreases due to oxidation and unit cost increases
Solution Approach 1:
The patent replaces expensive and unstable metal reflective layers with a more economical and stable polymer-based radiative cooling layer. The polymer layer achieves comparable or superior radiative cooling performance through high infrared emissivity while being resistant to oxidation and cost-effective.
4Illumination intensity
If white pigment paint is used, then visible light reflectance improves, but infrared emissivity and ultraviolet reflectance are insufficient reducing radiative cooling ability
Solution Approach 1:
The patent changes the optical parameters by selecting a polymer material with specific spectral properties: high infrared emissivity in the 8-14 μm atmospheric window and high ultraviolet reflectance. This parameter optimization allows the material to outperform white pigment paint in both infrared and ultraviolet ranges while maintaining visible light reflectance.
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 colored laminate achieves excellent visible and infrared light reflectance, efficient infrared radiation, and improved radiative cooling performance, while maintaining durability and color stability, making it suitable for vehicle exteriors and other applications.
Implementation Method 1
a first light reflecting layer formed on the colored layer and having a reflectance equal to or higher than 80% for light having a wavelength in a range from 780 to 1,300 nm
Implementation Method 2
an infrared-ray radiating layer formed on the adhesive layer
Implementation Method 3
a second light reflecting layer formed on the first light reflecting layer and including a first metal protective layer, a metal layer, and a second metal protective layer
Data Source
AI summary
An embodiment colored laminate for radiative cooling includes a colored layer including a first thermoplastic resin, a first light reflecting layer on the colored layer and having a reflectance equal to or higher than 80% for light having a wavelength in a range from 780 to 1,300 nm and a transmittance equal to or higher than 70% for visible light having a wavelength in a range from 400 to 780 nm, a second light reflecting layer on the first light reflecting layer, the second light reflecting layer including a first metal protective layer, a metal layer, and a second metal protective layer sequentially stacked on the first light reflecting layer, an adhesive layer on the second light reflecting layer, and an infrared-ray radiating layer on the adhesive layer.