| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of an extremely useful biaxially stretched polyester film for twist wrapping excellent in film forming properties and thickness uniformity and having good twist properties. SOLUTION: In the manufacturing method of the biaxially stretched polyester film for twist wrapping in which a first step stretching of a sheet solidified by cooling rolls is carried out in an lateral direction after melting and extruding a polyester, then heat treating is carried out in a constant length in a width direction, and thereafter a second step stretching is carried out in a longitudinal direction, the heat treating between the first stretching in the width direction and the second step stretching in the longitudinal direction is carried out at a temperature between the glass transition temperature of the polyester and the glass transition temperature +20°C for 0.5 to 3 sec, and a maximum height of the film surface is set to be 5 to 7μm. COPYRIGHT: (C)2007,JPO&INPIT |
