Polypropylene Front Sheet Composition for UV-Stable Photovoltaic Elements
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Solution Overview
Problem
Existing polypropylene materials used in photovoltaic elements deteriorate due to UV radiation and heat, leading to mechanical strength loss and color change, with phenolic antioxidants providing limited protection and yellowing issues.
Innovation Solution
A polypropylene composition comprising a mixture of high and low molecular weight hindered amine light stabilizers, ultraviolet synergists and absorbers, and antioxidant additives, including phenolic antioxidants and phosphites, to enhance UV stability and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phenolic antioxidants are used to protect polypropylene against thermo-oxidative degradation, then stabilization effectiveness is improved, but yellowing occurs due to oxidation to coloured quinonoid compounds
Solution Approach 1:
The patent combines phenolic antioxidants with phosphites and light stabilizers in a synergistic formulation. The phosphites decompose hydroperoxides formed during degradation, while light stabilizers prevent UV-induced oxidation, thereby protecting the phenolic antioxidant from oxidizing to colored quinonoid compounds and maintaining both stabilization effectiveness and color stability.
Solution Approach 2:
Phosphites act as intermediary compounds that decompose hydroperoxides before they can oxidize the phenolic antioxidant to colored quinonoid compounds. This intermediary action protects the phenolic antioxidant from harmful oxidation while maintaining its stabilization effectiveness.
2Productivity
If polypropylene is used as front layer material, then manufacturing efficiency and recyclability are improved, but UV degradation leads to mechanical strength loss and color changes
Solution Approach 1:
The patent incorporates stabilizing additives (phenolic antioxidants, phosphites, and light stabilizers) into the polypropylene formulation before manufacturing. These additives preemptively protect the polypropylene from UV degradation and thermo-oxidative degradation, preventing mechanical strength loss and color changes before they occur during service.
Solution Approach 2:
The patent creates a composite material system by combining polypropylene with multiple stabilizing additives (phenolic antioxidants, phosphites, and light stabilizers) in specific formulations. This composite approach provides comprehensive protection against UV degradation and thermo-oxidative degradation, maintaining mechanical strength while preserving the manufacturing efficiency and recyclability of polypropylene.
3Adaptability or versatility
If polypropylene is exposed to severe UV radiation and high heat, then application requirements for building and construction are met, but material deterioration occurs
Solution Approach 1:
The patent merges multiple stabilizing mechanisms into a single formulation: phenolic antioxidants provide thermo-oxidative degradation protection, phosphites decompose hydroperoxides, and light stabilizers (including benzophenone, benzotriazole, triazine type UV absorbers, hindered hydroxy-benzoates, and hindered amine compounds) provide UV radiation protection. This synergistic combination enables the polypropylene to withstand severe UV radiation and high heat conditions required for building and construction applications while maintaining material stability.
Solution Approach 2:
The patent develops a composite stabilizing formulation that integrates multiple additive systems working synergistically to protect polypropylene against severe environmental conditions. This composite approach provides comprehensive protection against both UV radiation and high heat, enabling the material to meet the demanding weather resistance requirements of building and construction applications while maintaining 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 composition provides improved UV stability, transparency, and mechanical strength, enabling efficient manufacturing and recycling of photovoltaic modules with reduced yellowing and degradation.
Implementation Method 1
a mixture of light stabilizing additives; said mixture comprising: i) a high molecular weight hindered tertiary amine light stabilizer (t-HM-HALS)... ii) a low molecular weight hindered secondary amine light stabilizer (s-LM-HALS)... iv) an ultraviolet absorber
Implementation Method 2
Phenolic antioxidant (PAO) additives are widely employed to protect polypropylene random (PP random) against thermo-oxidative degradation during processing and in service conditions... phenolic antioxidants have been used in combination with phosphites which are known to enhance the effectiveness of the phenolic antioxidants due to complementary and synergistic mechanisms of action (e.g. decomposition of hydroperoxides formed in the polymer at high temperature and in the presence of oxygen)
Data Source
AI summary
The present invention relates to a photovoltaic element, comprising a front layer, a back layer, and a plurality of photovoltaic cells, which photovoltaic cells are present between the front layer and back layer, wherein the front layer consists of a polypropylene composition, comprising: a) a random polypropylene resin; b) a mixture of light stabilizing additives; said mixture comprising: i) a high molecular weight hindered tertiary amine light stabilizer (t-HM-HAL S) having a weight average molecular weight of at least 1600 g/mol; ii) a low molecular weight hindered secondary amine light stabilizer (s-LM-HALS) having a weight average molecular weight of below 1000 g/mol; iii) an ultraviolet synergist, being a n-alkyl-3,5-dialkylated 4-hydroxybenzoate; iv) an ultraviolet absorber, being a hydroxybenzotriazole compound or a hydroxyl benzophenone compound or a mixture thereof; c) a mixture of antioxidant additives; said mixture comprising: i) a phenolic antioxidant; and ii) a phosphite additive. The invention also relates to a polypropylene composition and to the use thereof as front layer.