Transparent Multilayer Glazing for Thermal Management
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Solution Overview
Problem
Polycarbonate-based thermoplastic materials used in glazing applications are prone to heating due to IR radiation, and existing solutions for thermal protection, such as IR-reflecting additives and metal layers, either opacity the material or provide inadequate weathering stability and optical properties.
Innovation Solution
A transparent multilayer article is developed with a metal layer positioned behind a polycarbonate substrate, incorporating IR absorbers and a scratch-resistant coating, which effectively reduces interior heating without a metallic mirror effect and ensures long-term weathering stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If IR-reflecting additives are incorporated into polycarbonate, then thermal protection is improved, but transparency is worsened (material becomes opaque)
Solution Approach 1:
The patent introduces a metal layer as an intermediary component between the polycarbonate substrate and the environment. This metal layer serves as a mediator that provides IR reflection and thermal protection without requiring the polycarbonate itself to contain opaque additives. The metal layer absorbs or reflects IR radiation while allowing the polycarbonate to remain transparent to visible light.
Solution Approach 2:
The patent creates a composite structure consisting of polycarbonate substrate combined with a metal layer. This composite material approach allows combining the transparency and formability of polycarbonate with the IR reflection properties of metal, achieving both optical clarity and thermal protection that cannot be obtained with either material alone.
2Temperature
If metal layers are applied to polycarbonate for IR reflection, then thermal protection is improved, but weathering stability is worsened
Solution Approach 1:
The patent applies a protective coating to the metal layer before final assembly or exposure to environmental conditions. This preliminary protective layer prevents oxidation and degradation of the metal layer, ensuring long-term weathering stability while maintaining the IR reflection properties. The protective coating is applied in advance to prevent deterioration rather than attempting to repair it later.
3Object-generated harmful factors
If IR-absorbing additives are used in polycarbonate, then thermal radiation blocking is improved, but heating of the material itself is worsened
Solution Approach 1:
The patent converts the harmful effect of IR absorption into a beneficial reflection mechanism. Instead of using additives that absorb IR radiation and convert it to heat within the polycarbonate, the metal layer is designed to reflect IR radiation away from the interior space. This converts the potential harm of IR interaction into a beneficial reflection effect that protects without heating the material or interior.
4Object-generated harmful factors
If the metal layer is positioned on the front side of polycarbonate, then IR reflection is improved, but optical properties are worsened (metallic mirror effect)
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the metal layer on the rear side of the polycarbonate substrate rather than on the front side. This inversion allows IR radiation to first pass through the transparent polycarbonate and then be reflected by the metal layer, achieving effective thermal protection while maintaining optical clarity and avoiding the unsightly metallic mirror effect that would occur with front-side placement.
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 significantly reduces interior heating while maintaining transparency and weathering stability, making it suitable for glazing applications in vehicles and buildings, and provides enhanced scratch resistance.
Implementation Method 1
at least one metal layer d comprising at least one element selected from Ag, Al, Au, Pt, Fe, Cr, Sn, In, Ti, Pd, Nb, Cu, V or alloys thereof
Implementation Method 2
the substrate layer contains at least 0.001% by weight of an IR absorber other than carbon black
Data Source
AI summary
The invention relates to transparent multilayer structures and glazings or glazing elements comprising said multilayer structures, which are suitable for screening an indoor space from a radiation source, comprising, in this order a) optionally a protective layer a, b) a substrate layer based on a thermoplastic polymer, especially an aromatic polycarbonate, having a luminous transmittance in the range of 380 to 780 nm of at least 0.3%, determined at a layer thickness of 4 mm according to DIN ISO 13468-2:2006 (D65, 10°), and a TDS value of less than 40%, determined according to ISO 13837:2008 at a layer thickness of 4 mm, the substrate layer containing at least 0.001 wt. % of an IR absorber different from carbon black, c) if necessary, another layer c based on a thermoplastic polymer with a maximum thickness of 600 μm, d) at least one metal layer d, containing at least one element selected from the group including Ag, Al, Au, Pt, Fe, Cr, Sn, In, Ti, Pd, Nb, Cu, V or their alloys, the sum of thicknesses of all metal layers being 1 nm to not more than 30 nm, and e) optionally a protective layer e, at least 60% of the substrate layer b being covered by metal layer d, the layers following layer d, including the protective layer e, when added up, having a thickness of not more than 100 nm and the metal layer being applied to the side of the substrate layer b designed to be on the face of the multilayer structure facing away from the radiation source.