Polyamide Polyester Multilayer Film Adhesion via Graft Copolymer
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Solution Overview
Problem
Conventional solar modules with fluoropolymer films exhibit low adhesion to the sealing layer and inadequate electrical insulation, requiring thick polyester films for mechanical stability, and existing solutions do not ensure long-term adhesion between polyamide and polyester layers under weathering conditions.
Innovation Solution
A multilayer film comprising polyamide and polyester layers with a polyamine-polyamide graft copolymer, where the copolymer includes monomers with at least 4 nitrogen atoms and polyamide-forming units, providing improved adhesion and stability over the service life of the composite, exceeding 20 years.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoropolymer films are used as back cover, then weathering resistance is improved, but adhesion to sealing layer deteriorates and electrical insulation becomes insufficient
Solution Approach 1:
The patent employs a composite structure consisting of a fluoropolymer outer layer for weathering resistance and a polyester inner layer for adhesion and electrical insulation. This multi-layer composite material combines the advantages of different materials to simultaneously achieve weathering resistance, good adhesion to the sealing layer, and sufficient electrical insulation properties.
2Strength
If polyester film thickness is increased for mechanical stability, then mechanical strength is improved, but device complexity increases
Solution Approach 1:
Instead of using a single thick polyester film, the patent employs a composite structure with fluoropolymer and polyester layers in specific thickness ratios. This allows achieving the required mechanical stability with optimized, thinner individual layers, thereby reducing overall complexity while maintaining strength.
3Strength
If polyamide and polyester layers are combined, then mechanical properties are improved, but adhesion between layers deteriorates
Solution Approach 1:
The patent carefully designs the composite structure with fluoropolymer outer layer and polyester inner layer, where each material contributes its advantageous properties. The fluoropolymer provides weathering resistance while the polyester ensures good adhesion to the sealing layer and sufficient electrical insulation, achieving synergistic effect.
Solution Approach 2:
The patent applies different materials to different locations within the back cover structure: fluoropolymer is used in the outer layer where weathering resistance is most needed, while polyester is used in the inner layer where adhesion and electrical insulation are critical. This local differentiation optimizes performance for each specific function.
4Duration of action of stationary object
If service life is extended beyond 20 years, then durability is improved, but resistance to atmospheric effects deteriorates
Solution Approach 1:
The patent employs the fluoropolymer outer layer as a protective barrier that shields the inner polyester layer and the solar cell system from atmospheric effects such as UV radiation, moisture, and oxidation. This beforehand protection enables the module to maintain its performance and adhesion properties throughout the extended 20-year service life.
Data Source
AI summary
A multilayer film containing layers of polyamide and polyester, suitable as a back cover for a photovoltaic module is provided. The film comprises, in the order listed: a) a layer which comprises at least 35% by weight of polyamide; c) a layer which comprises at least 35% by weight, of a thermoplastic polyester; and e) a layer which comprises at least 35% by weight of polyamide; wherein the layers a) and e) further comprise 0.1 to 60% by weight, of a polyamine-polyamide graft copolymer, or the layer c) further comprises 0.1 to 30% by weight of polyamine-polyamide graft copolymer. The polyamine-polyamide graft copolymer comprises as copolymerized monomers: a polyamine having at least 4 nitrogen atoms and at least one polyamide-forming unit selected from the group consisting of a lactam, an ω-aminocarboxylic acid and an equimolar combinations of a diamine and a dicarboxylic acid. In another embodiment, adhesion promoting layers are placed between the layers.