| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a laminated polyester film having high dimensional stability and well-balanced between mechanical strength in both of longitudinal and lateral directions, Young's modulus and thermal characteristics such as a heat shrinkage factor or the like. SOLUTION: A laminated polyester non-oriented film, which is characterized in that either one of mutually different polyester layers contains an aromatic dicarboxylic acid having a metal sulfonate group and polyalkylene glycols and/or a saturated aliphatic dicarboxylic acid as copolymerizable components, is unidirectionally subjected to first stage orientation in a draw ratio of 2.7-5.0 times and subsequently subjected to second stage orientation in a draw ratio of 1.2-5.0 times in the direction right-angled to the first stage orientation direction. In this case, a temperature in the first stage orientation is selected so that the refractive index in the direction right-angled to the orientation direction within the plane of the film after the first stage orientation becomes≤1.573 and a temperature in the second stage orientation is set to a temperature from the glass transition temperature Tg°C of the polyester layer having a higher glass transition temperature among two polyester layers constituting the laminated polyester film to (Tg+35)°C to orient the film before thermally fixing the same. COPYRIGHT: (C)2004,JPO&NCIPI |
