| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for producing a polyester film, in which the polyester film is produced stably, which film is used suitably for optical applications, is stretched obliquely, and has an excellent thickness fluctuation.SOLUTION: The method for producing the polyester film comprises the steps of: using a tenter type stretching device, holding both edges of an original polyester film in the width direction by holders; and varying a pitch of the adjacent holders in the advancing direction of the original polyester film in different positions by using the holders at both edges to stretch the original polyester film obliquely. The wind speed of such a zone is set to be 5-20 m/second that the pitch of the adjacent holders is varied to stretch the polyester film in the advancing direction and a deviation of the wind speed in the same zone is set to be 20% or smaller.</p> |
