| 摘要 |
PURPOSE:To provide high-strength polyester film. CONSTITUTION:The modulus of elasticity in tension in the machine direction of film EMO (kg/mm<2>) and the modulus of elasticity in tension in the transverse direction of the film ETD (kg/mm<2>) of the polyester film concerned satisfy the following formulae (1) and (2) and the polyester film, which is stretched at least in the machine direction, is stretched in the transverse direction and heat- treated and finally stretched again in the machine direction so as to produce the polyester film concerned: EMD+ETD>=1,300...(1), nalpha<=1.5153-2.1X10<-5>(EMD+ ERTD)...(2), T2<=140(at T1<=110)...(3), T2<=T1+30 (at T1>110)...(4) and T2-20<=T3<=200...(5), in which T1 represents crosswise orienting temperature ( deg.C), T2 represents heat-treating temperature ( deg.C) at the state after crosswise orienting and before re-lengthwise prienting, T3 represents re-lengthwise orienting temperature ( deg.C). |
