ETFE Film Crystallinity Control for Solar Transparency
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Solution Overview
Problem
Conventional ETFE films have insufficient transparency and poor heat resistance, which affects the power generation efficiency of solar batteries, and are not cost-effective.
Innovation Solution
A novel ETFE film production method using a copolymer with specific composition, including ethylene, tetrafluoroethylene, and (fluoroalkyl)ethylene units, with controlled crystallinity and processing conditions to achieve high light transmittance and low haze, resulting in a film with crystallinity of 68% or less, improved transparency, and enhanced heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional ETFE film is used, then heat resistance and weather resistance are improved, but transparency is insufficient compared to glass
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallinity of the ETFE film through specific cooling conditions during production. By maintaining the cooling roll temperature at 80-140°C and using hot air at 50-160°C, the crystallinity is controlled to 40-60%, which optimizes both heat resistance and transparency. This parameter control resolves the contradiction by finding the optimal balance point where the film maintains thermal stability while achieving sufficient light transmission for solar battery applications
2Productivity
If ETFE film is not cooled uniformly during production, then production efficiency is improved, but the film develops poor transparency, loosening, or wrinkles
Solution Approach 1:
The patent employs parameter changes by establishing specific temperature ranges for the cooling process. The cooling roll temperature is set to 80-140°C and hot air temperature to 50-160°C, which creates optimal cooling conditions that prevent wrinkles and maintain film uniformity while allowing efficient production. This resolves the contradiction by defining the precise thermal parameters needed for high-quality film production
Solution Approach 2:
The patent uses hot air as an intermediary medium to control the cooling process. By blowing hot air at 50-160°C onto the film during cooling, the temperature distribution is uniformized, preventing localized cooling defects such as wrinkles and transparency variations. This intermediary approach allows efficient production while maintaining high manufacturing precision
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 resulting ETFE film exhibits excellent transparency, heat resistance, and cost efficiency, leading to high power generation efficiency and prolonged operation under high-temperature conditions for solar batteries.
Implementation Method 1
a copolymer having a ratio of (polymerization unit derived from tetrafluoroethylene)/(polymerization unit derived from ethylene) of 30/70 to 70/30 (molar ratio), is crystalline
Implementation Method 2
a biaxially stretched film such as an ethylene-tetrafluoroethylene-based copolymer film having significantly improved light transmittance
Data Source
Figure 1~3
AI summary
The present invention aims to provide an ETFE film having excellent transparency and heat resistance and cost efficiency. The present invention relates to a film including a copolymer containing an ethylene unit, a tetrafluoroethylene unit, and a (fluoroalkyl)ethylene unit represented by Formula (1): CH2=CX-Rf (1) wherein X represents H or F, and Rf represents a fluoroalkyl group having 2 or more carbon atoms, the copolymer containing the (fluoroalkyl)ethylene unit in an amount of 0.8 to 2.5 mol% relative to the amount of all the monomer units and containing the ethylene unit and the tetrafluoroethylene unit at a molar ratio of 30.0/70.0 to 50.0/50.0, the film having a crystallinity of 68% or less, the crystallinity being calculated on the basis of a diffraction intensity curve of the film resulting from X-ray diffraction measurement.