Solar Module Sealing Sheet Structure Without Crosslinking
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Solution Overview
Problem
Current sealing material sheets for solar-cell modules, particularly those using polyethylene-based resins, face challenges in achieving high heat resistance, molding characteristics, and tensile shear adhesion force at normal temperature without crosslinking processing, which affects their productivity and performance in double-sided glass protecting substrate type solar-cell modules.
Innovation Solution
A multi-layer sealing material sheet configuration with a core layer and skin layers, where the core layer has a density of 0.880 g/cm3 to 0.930 g/cm3 and a melting point of 70° C. or higher, and the skin layer contains silane-modified polyethylene-based resin with a weight average molecular weight of 70000 to 120000, ensuring high tensile shear adhesion force and maintaining heat resistance and molding characteristics without crosslinking processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crosslinking treatment is performed to improve heat resistance, then heat resistance is reliably improved, but molding characteristics deteriorate and followability to surface irregularities cannot be maintained
Solution Approach 1:
The sealing material sheet is divided into a core layer and skin layers with different functions. The core layer provides heat resistance through high melting point polyethylene resin, while the skin layer provides molding characteristics and followability through low density polyethylene resin with silane modification. This segmentation allows each layer to optimize its properties without compromising the other.
Solution Approach 2:
Different regions of the sealing material sheet have different compositions and properties. The skin layer has lower density (0.880-0.900 g/cm³) and lower melting point for better molding characteristics, while the core layer has higher density (0.880-0.930 g/cm³) and higher melting point for heat resistance. This local differentiation resolves the contradiction between heat resistance and molding characteristics.
2Ease of operation
If density of polyethylene-based resin sealing material sheet is decreased to improve transparency and flexibility, then transparency and flexibility are improved, but heat resistance becomes insufficient
Solution Approach 1:
The sealing material is segmented into skin layers optimized for flexibility and transparency (lower density) and a core layer optimized for heat resistance (higher density). This allows the flexible skin layers to contact and follow surface irregularities while the dense core layer provides the necessary thermal stability.
Solution Approach 2:
The sealing material sheet uses a composite structure combining polyethylene-based resin with silane modification in the skin layer and high melting point polyethylene resin in the core layer. This composite approach enables simultaneous achievement of flexibility (through silane-modified low density resin) and heat resistance (through high melting point core layer) that cannot be achieved with a single homogeneous material.
3Temperature
If crosslinking treatment is performed to improve heat resistance, then heat resistance is improved, but productivity decreases due to additional processing steps and decreased film formation ability
Solution Approach 1:
The invention extracts the crosslinking step from the manufacturing process by achieving heat resistance through material composition and structure design instead. The high melting point core layer and silane-modified skin layer provide inherent heat resistance without requiring post-molding crosslinking treatment, thereby eliminating the additional processing step and maintaining high productivity.
Solution Approach 2:
Heat resistance is built into the material structure during sheet formation rather than being added later through crosslinking. The core layer is pre-configured with high melting point polyethylene resin and the skin layer is pre-modified with silane groups, so that heat resistance is inherent from the start, eliminating the need for subsequent crosslinking processing.
4Ease of manufacture
If EVA resin is used as sealing material, then processability and workability are good, but long-term durability deteriorates due to decomposition and acetic acid generation
Solution Approach 1:
The invention changes the chemical composition parameters by using polyethylene-based resin with silane modification instead of EVA resin. This parameter change eliminates the decomposition and acetic acid generation issues inherent to EVA while maintaining good processability through the silane-modified low density polyethylene in the skin layer.
Solution Approach 2:
The sealing material uses a composite of polyethylene-based resin with silane modification, combining the processability advantages of polyethylene with the long-term stability benefits of silane crosslinking capability. The skin layer contains silane-modified polyethylene that provides both ease of manufacturing and improved long-term durability without the decomposition problems of EVA resin.
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 proposed solution enhances the productivity and performance of the sealing material sheet by providing high tensile shear adhesion force at normal temperature, heat resistance, and molding characteristics, effectively addressing the limitations of existing polyethylene-based resin sheets in solar-cell modules.
Implementation Method 1
the skin layer contains silane-modified polyethylene-based resin... ensuring high tensile shear adhesion force
Implementation Method 2
the core layer has a density of 0.880 g/cm3 to 0.930 g/cm3 and a melting point of 70° C. or higher
Implementation Method 3
the core layer has a density of 0.880 g/cm3 to 0.930 g/cm3 and a melting point of 70° C. or higher
Data Source
AI summary
To provide a sealing material sheet for a solar-cell module that has high productivity without performing crosslinking processing, and has a high tensile shear adhesion force at normal temperature at a high level in addition to heat resistance and molding characteristics. A sealing material sheet is a multi-layer sheet using a polyethylene-based resin as a base resin, a core layer has a density of 0.880 g/cm3 to 0.895 g/cm3 and a melting point of 70° C. or higher, a skin layer has a density of 0.880 g/cm3 to 0.910 g/cm3 and a melting point of 90° C. or lower and contains a silane-modified polyethylene-based resin, a weight average molecular weight of the silane-modified polyethylene-based resin contained in the skin layer 11 in terms of polystyrene is 70000 to 120000, and a polymerized silane amount of the skin layer in the whole resin component is 300 ppm to 2000 ppm.