| 摘要 |
PURPOSE:To improve dimensional stability, by a method wherein the distortional modulus of elasticity and a thermal shrinkage factor in a longitudinal direction of a film and a kinetic thermal change factor in dimensions and Young's modulus in a width direction of the same possess respectively set values. CONSTITUTION:The distortional modulus of elasticity G2 (Newton/m<2>) and a thermal shrinkage factor sigmab(%) at 70 deg.C of a longitudinal direction of a film is 2X10<10>N/m<2>>=G2>=5.0X10<9>N/m<2>0.8%>=sigmab>=0, a kinetic thermal change factor in dimensions of a width direction of the film at 120-170 deg.C falls within a range of 0.18-1.5% and a Young's modulus at 23 deg.C of the same possesses 380-700kg/mm<2>. Then polyethylene terephthalate constituting a biaxially oriented film may be either homopolymer or copolymer. In case of the copolymer, diethylene glycol, propylene glycol, neopentyl glycol and polyethylene glycol are mentioned as a copolymerizing ingredient. With this construction, a heat treatment process where the thermal shrinkage factor after calender is lowered through application of a magnetic layer to the film is omitted or shortened. |
