Multi-layer Polyolefin Sealing Sheet for Solar Modules
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Solution Overview
Problem
Conventional sealing material sheets for solar-cell modules, primarily using polyolefin-based resins, face challenges in balancing flexibility and heat resistance, leading to contamination of vacuum laminators during processing and insufficient long-term durability under high temperature environments.
Innovation Solution
A multi-layered sealing material sheet with a core layer containing polypropylene for enhanced heat resistance and a skin layer made of low-density polyethylene, optimized in composition and thickness to maintain flexibility and prevent contamination, integrated with a rear-surface protecting sheet for improved solar-cell module assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the density of polyethylene-based sealing material sheet is decreased to improve transparency and flexibility, then flexibility is improved, but heat resistance deteriorates and excessive flowing occurs during heating processing
Solution Approach 1:
The patent applies composite materials by combining low-density polyethylene (providing flexibility and transparency) with polypropylene (providing heat resistance) in a multi-layered structure. The core layer uses low-density polyethylene for flexibility, while the skin layer uses polypropylene for heat resistance, creating a composite material that achieves both flexibility and heat resistance simultaneously
Solution Approach 2:
The sealing material sheet is segmented into multiple layers with different functions: a core layer made of low-density polyethylene for flexibility and transparency, and skin layers made of polypropylene for heat resistance and contamination prevention. This segmentation allows each layer to optimize its specific function without compromising the other
2Temperature
If crosslinking agent is added to improve heat resistance, then heat resistance is improved, but flexibility deteriorates and film formation ability decreases
Solution Approach 1:
The patent changes the material composition parameters by selecting specific resins with appropriate melting points and thermal properties. The polypropylene in the skin layer has a higher melting point than the low-density polyethylene in the core layer, providing heat resistance through material selection rather than chemical crosslinking, thus maintaining flexibility
3Duration of action of stationary object
If sealing material sheet is used for long period, then durability is improved, but decomposition occurs and acetic acid gas is generated affecting solar cell element
Solution Approach 1:
The patent uses polypropylene and low-density polyethylene which are more stable and less prone to decomposition compared to EVA resin. These polyolefin-based materials do not generate acetic acid gas during long-term use, providing better durability without the harmful decomposition effects
Data Source
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AI summary
Provided are: a sealing material sheet for solar cell modules, which mainly uses a polyethylene resin and achieves a good balance between heat resistance and flexibility suitable for sealing sheets for solar cell modules; and a sealing material-integrated rear-surface protecting sheet which uses this sealing material sheet for solar cell modules. A sealing material sheet 1 for solar cell modules, which has a thickness of from 200 µm to 400 µm (inclusive) and comprises a core layer 11 and a skin layer 12, and wherein: the core layer 11 contains from 5% by mass to 40% by mass (inclusive) of a polypropylene and from 60% by mass to 95% by mass (inclusive) of a low-density polyethylene having a density of from 0.910 g/cm3 to 0.940 g/cm3 (inclusive) in terms of content ratios to all the resin components; and the skin layer 12 contains from 80% by mass to 100% by mass (inclusive) of a low-density polyethylene having a density of 0.880 g/cm3 or more but less than 0.910 g/cm3 in terms of a content ratio to all the resin components, without containing a polypropylene.