Multilayer Polyester Film for PV Backsheets
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Solution Overview
Problem
Current biaxially oriented multilayer polyester films for photovoltaic panel backsheets face challenges in achieving high transparency, low haze, ease of handling, hydrolysis resistance, and light stability while maintaining mechanical integrity and adhesion properties.
Innovation Solution
A multilayer biaxially oriented transparent polyester film structure comprising a core layer of biaxially oriented aromatic polyester, such as polyethylene terephthalate, and outer layers with particles resulting from the reaction between metal compounds and monomeric or oligomeric units, optimized for low haze, improved handling, and enhanced hydrolysis and light stability, along with the incorporation of light stabilizers and specific additives for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent polyester films are used for PV panel backsheets, then light transmission is improved, but hydrolysis resistance deteriorates
Solution Approach 1:
The patent employs a multilayer composite structure where the core layer uses transparent polyester for light transmission while outer layers incorporate hydrolysis-resistant materials. This composite approach allows simultaneous achievement of optical transparency and hydrolytic stability in the final backsheet product.
2Strength
If multilayer polyester films are used to improve mechanical properties, then strength is improved, but manufacturing complexity increases
Solution Approach 1:
The backsheet is divided into functionally distinct layers: a core layer providing mechanical strength and outer layers providing hydrolysis resistance and adhesion. This segmentation allows each layer to be optimized for its specific function while maintaining overall manufacturing feasibility through standardized multilayer processing.
3Strength
If opaque materials are used in PV panels, then mechanical integrity is improved, but transparency deteriorates
Solution Approach 1:
Different regions of the backsheet structure are assigned different optical and mechanical properties: the core layer is designed for mechanical strength with appropriate opacity, while the overall assembly maintains transparency through the strategic placement and thickness control of transparent outer layers, achieving local optimization of both properties.
Data Source
AI summary
A biaxially oriented multilayer transparent film including at least two layers of polyester, respectively a core layer and at least one outer layer, which can be identical or different, wherein: i) at least the core layer includes at least one biaxially oriented transparent polyester PE1, ii) at least one of the outer layers includes, on the one hand, at least one biaxially oriented polyester PE2, and, on the other hand, particles coming from the reaction between at least one metal compound and at least one monomeric or oligomeric unit of PE2, the particles having more preferably a d50—as μm and following an order of preference—between 0.5 and 5; between 1.0 and 4, and between 1.5 and 3.0. Also relates to the manufacture of this film and its applications as a laminate in particular in the backsheets of photovoltaic cells.