Solar Reflector Coating Structure for UV-Stable Abrasion Resistance
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Solution Overview
Problem
Solar reflectors made of flexible specular silver mirrors face issues with durability and ultraviolet degradation, leading to loss of dimensional stability and aesthetic appearance due to corrosion and UV transmission, which existing protective measures fail to adequately address.
Innovation Solution
A solar reflector construction incorporating an abrasion-resistant coating, a reflective metal layer, an adhesive layer, and a polymer film layer, where the polymer film is positioned between the abrasion-resistant coating and the reflective metal layer or the adhesive layer, providing enhanced durability and UV stability while maintaining high reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thin layer of silver is vacuum-deposited on a flexible polymer substrate to provide high specular reflectance, then the solar reflector achieves higher reflectivity compared to aluminum, but the silver layer allows ultraviolet light transmission that degrades the polyester substrate
Solution Approach 1:
A clear polymer protective overlay is introduced as an intermediary layer between the silver reflective layer and the polyester substrate. This overlay acts as a mediator that blocks ultraviolet light from reaching and degrading the substrate while allowing the silver layer to maintain its high specular reflectance properties.
Solution Approach 2:
The solar reflector is constructed as a composite structure combining multiple materials: a flexible polyester substrate, a vacuum-deposited silver layer for reflectance, and a clear polymer protective overlay for UV protection. This composite approach allows each layer to perform its specific function while working together as an integrated system.
2Reliability
If corrosion inhibitors are incorporated into adhesives or protective film coatings to reduce silver corrosion, then the mirror's corrosion resistance is improved, but the inhibitors impart unacceptable color to the mirror over time
Solution Approach 1:
A clear polymer protective overlay is positioned as an intermediary barrier between the silver layer and the corrosive environment. This overlay protects the silver from corrosion without introducing discoloring chemicals, thereby maintaining both corrosion resistance and aesthetic appearance.
Solution Approach 2:
The harmful corrosion-inhibiting chemicals that cause discoloration are extracted from the system. Instead of using chemically active inhibitors that discolor, the patent relies on the physical barrier protection of the clear polymer overlay to prevent corrosion without compromising appearance.
3Stability of the object's composition
If ultraviolet light absorbers are incorporated into a protective polymer overlay to reduce substrate degradation, then the polyester support stability is improved, but the absorbers aggravate silver corrosion
Solution Approach 1:
A clear polymer protective overlay serves as an intermediary that blocks ultraviolet light from reaching the polyester substrate without introducing UV absorbers that would contact and corrode the silver layer. The overlay provides UV protection through its inherent properties rather than chemical absorbers.
Solution Approach 2:
UV absorber chemicals are extracted from the protective overlay formulation. The patent uses a clear polymer overlay that provides UV protection through its physical structure and inherent properties rather than through chemical absorbers that would be in contact with and corrode the silver layer.
4Ease of manufacture
If conventional polymer film reflectors are used to reduce cost and improve flexibility, then manufacturing cost is reduced and design flexibility is improved, but abrasion resistance is insufficient
Solution Approach 1:
The reflector is constructed as a composite structure combining a flexible polymer substrate with a vacuum-deposited metal layer and a protective overlay. This composite construction maintains the cost and flexibility advantages of polymer films while adding the abrasion resistance of the protective overlay.
Solution Approach 2:
The patent uses a flexible polymer substrate with thin film layers deposited on it, maintaining the flexibility and ease of manufacture of thin film structures while adding protective functionality through the overlay layer that provides abrasion resistance.
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 high solar reflectance, abrasion resistance, and mechanical integrity, reducing costs and improving design flexibility compared to conventional reflectors, while maintaining specular reflectance and preventing significant degradation from UV exposure.
Implementation Method 1
a silvered composite lamina, having a thin layer of silver vacuum-deposited on the surface of a flexible polymer substrate
Implementation Method 2
a thin layer of silver, unlike a thin layer of aluminum, has a spectral window through which ultraviolet ('UV') light readily passes... The transmission of ultraviolet light through the silver layer degrades the underlying polyester substrate
Data Source
AI summary
Described herein are solar reflectors which provide a low cost reflector construction that has a unique set of attributes: high solar reflectance, abrasion resistance, UV stability, mechanical integrity, and flexibility. The abrasion resistance is enabled through incorporation of an abrasion-resistant coating into a polymer film metal mirror construction. Methods of using the solar reflectors in solar concentrating applications are also provided.