PVDF Copolymer Back Sheet for Solar Cells
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Solution Overview
Problem
Conventional solar cell back sheets made with fluorine-based resins face issues with adhesivity to the substrate and require high drying temperatures, leading to increased production costs and reduced productivity and quality due to thermal deformation.
Innovation Solution
A solar cell back sheet featuring a polyvinylidene fluoride (PVDF)-based polymer with crystallinity between 10 to 40% is used, which can be dissolved in solvents at lower boiling points, allowing for low-temperature drying and improved adhesivity through copolymerization with comonomers like hexafluoropropylene and the inclusion of additives such as methyl methacrylate and glycidyl methacrylate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorine-based resin is used to form the resin layer, then weatherability and durability are improved, but adhesivity to the substrate layer deteriorates and high drying temperature is required
Solution Approach 1:
The patent changes the chemical composition parameters of the fluorine-based resin by incorporating specific comonomers (CTFE, HFP, TFE) in controlled amounts. This modifies the resin's properties to achieve both good adhesivity and weatherability without requiring high drying temperatures, thus resolving the contradiction between durability and ease of manufacture
Solution Approach 2:
The patent creates a composite fluorine-based resin system by combining PVDF with multiple comonomers (CTFE, HFP, TFE) and additives (methyl methacrylate, glycidyl methacrylate). This composite approach allows the resin layer to simultaneously achieve excellent adhesivity to the substrate and superior weatherability, while enabling low-temperature processing
2Reliability
If a fluorine-based resin solution requiring high drying temperature is used, then the resin layer can be formed, but production cost increases due to expensive drying apparatus
Solution Approach 1:
The patent modifies the resin composition to enable low-temperature drying by incorporating comonomers with lower glass transition temperatures and appropriate molecular weight distributions. This parameter change allows the use of conventional, cost-effective drying apparatus while still forming a high-quality resin layer with excellent weatherability
3Reliability
If high drying temperature is applied to dry the fluorine-based resin solution, then the resin layer can be formed, but thermal deformation of the substrate layer occurs
Solution Approach 1:
The patent changes the drying temperature parameter from high temperature to low temperature (below 100°C) by modifying the resin composition. This allows complete solvent evaporation and proper resin layer formation without causing thermal deformation of the substrate, thus maintaining manufacturing precision while achieving reliable resin layer formation
Solution Approach 2:
The patent uses specific solvents as intermediaries that enable low-temperature processing. These solvents are carefully selected to provide appropriate viscosity and evaporation characteristics, allowing the resin to be applied and dried at low temperatures without compromising layer formation quality or causing substrate deformation
4Reliability
If the crystallinity of PVDF-based polymer is high, then durability is improved, but solubility in low boiling point solvents deteriorates
Solution Approach 1:
The patent optimizes the crystallinity parameter of PVDF-based polymer to a specific range (30-70%) rather than maximizing it. This parameter optimization maintains sufficient durability while ensuring adequate solubility in low boiling point solvents, enabling low-temperature processing. The presence of comonomers further modulates crystallinity and solubility balance
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
This approach reduces production costs, enhances the durability and weatherability of the back sheet, and minimizes thermal deformation, thereby improving the productivity and quality of solar cell modules.
Implementation Method 1
a polyvinylidene fluoride (PVDF)-based copolymer having a crystallinity of 10 to 40%... which can be dissolved in solvents at lower boiling points
Implementation Method 2
applying the coating solution onto at least one side of the substrate layer and then drying the applied coating solution at a temperature of 250 °C or lower to form a resin layer
Data Source
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AI summary
The present invention provides a solar cell back sheet including: a substrate layer, and a resin layer including a polyvinylidene fluoride (PVDF)-based polymer having a crystallinity of 50% or less, and a method of manufacturing the same. The solar cell back sheet is advantageous in that, since the drying temperature of the resin layer formed on at least one side of the substrate layer can be freely adjusted within the range of 250°C or less, preferably, 200°C or less, there can be improvements in the optimum conditions for obtaining optimum physical properties, minimization of the thermal deformation of the substrate layer, and the production cost and productivity of the solar cell back sheet.