METHOD FOR PRODUCING POLYESTER FILM FOR BACKSIDE PROTECTION FILM OF SOLAR CELL AND POLYESTER FILM FOR BACKSIDE PROTECTION FILM OF SOLAR CELL

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a polyester film suitable for a backside protection film of a solar cell with high productivity, which prevents the deterioration of mechanical properties even when being used in an environment of high temperature and humidity for a long period of time, and simultaneously has uniform and low thermal shrinkage in a lengthwise direction over in a width direction of the film.

SOLUTION: The method for producing the polyester film for the backside protection film of the solar cell comprises the steps of: subjecting a stretched film made of a polyester resin to heat-fixing treatment at a temperature lower than a melting point of the polyester resin by 35-65°C in a heat-fixing zone; passing the film through a highest temperature part of the heat-fixing zone; then cutting and separating the end of the film in an atmosphere of 140 to 175°C; and subjecting the film to relax heat treatment at a relaxation rate of 1.8 to 5.0% in a direction of continuously forming the film.

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