UV-Stabilized Polycarbonate Multilayer Glazing
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Solution Overview
Problem
Polycarbonate materials are not inherently UV stable, leading to insufficient long-term stability against yellowing, particularly in outdoor applications with high visual requirements such as glazing, where they fail to meet the ΔYI < 3 criteria under 30 MJ/m² irradiation at 340 nm after 10 years of weathering in Florida.
Innovation Solution
A multilayer product comprising a UV protective layer made of polyalkyl (meth)acrylate with a biphenyl-substituted triazine UV stabilizer and a polycarbonate layer, where the UV protective layer can be in the form of a film, co-extruded layer, or hardened lacquer, with specific compositions and concentrations of UV absorbers and HALS systems to achieve sufficient extinction and low degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If UV stabilizers are added to polycarbonate to protect from UV radiation, then UV protection is improved, but long-term stability against yellowing remains insufficient
Solution Approach 1:
The patent divides the protective function into two separate layers: a polycarbonate base layer and a UV-protective top layer containing polyalkyl (meth)acrylate and biphenyl-substituted triazine. This segmentation allows each layer to specialize - the polycarbonate provides structural integrity while the top layer handles UV filtration, resolving the contradiction between UV protection and long-term yellowing resistance.
Solution Approach 2:
The invention creates a composite multilayer structure combining polycarbonate with polyalkyl (meth)acrylate containing biphenyl-substituted triazine UV stabilizers. This composite approach leverages the complementary properties of both materials - the durability of polycarbonate and the superior UV stability of the acrylic layer - achieving both UV protection and long-term yellowing resistance.
2Object-affected harmful factors
If UV protection layers are applied to polycarbonate surfaces, then UV filtration is improved, but the complexity of the product structure increases
Solution Approach 1:
The patent combines the UV protective layer and polycarbonate base layer into a single integrated multilayer product where the layers are bonded together. This merging approach provides complete UV protection while maintaining a unified, manageable product structure rather than requiring separate application and maintenance of distinct components.
Solution Approach 2:
The invention applies UV protection specifically to the surface layer while keeping the bulk polycarbonate material unchanged. This local quality approach provides UV filtration exactly where needed (at the surface exposed to sunlight) without unnecessarily complicating the entire product structure or requiring modification of the bulk material properties.
3Use of energy by moving object
If conventional UV absorbers are used in polycarbonate layers, then UV absorption is achieved, but degradation occurs leading to yellowing over time
Solution Approach 1:
The patent introduces a biphenyl-substituted triazine compound as an intermediary UV stabilizer in the polyalkyl (meth)acrylate layer. This intermediary substance effectively absorbs UV energy and converts it to harmless thermal energy without degrading, preventing the UV radiation from reaching and degrading the polycarbonate layer, thus maintaining both UV absorption capability and long-term compositional stability.
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 multilayer product effectively filters out harmful UV radiation, preventing significant yellowing of polycarbonate surfaces, meeting the ΔYI < 3 requirement after 10 years of outdoor weathering, thereby ensuring long-term visual stability and performance.
Implementation Method 1
UV stabilizers are generally used, which absorb UV radiation and convert it into harmless thermal energy
Implementation Method 2
it is advantageous to effectively filter out the harmful UV radiation before it reaches the polycarbonate surface
Data Source
AI summary
The invention relates to a multilayered product comprising a first and a second layer. The second layer contains polycarbonate while the first layer represents a UV-protective layer which is based on polyalkyl(meth)acrylate and contains a biphenyl-substituted triazine as a UV stabilizer. The invention further relates to the production of said multilayered products as well as to products, e.g. glazings, which comprise the disclosed multilayered products.