| 摘要 |
PURPOSE:To improve perforation capability, and resolution and resistance to wear during printing by preparing film consisting of a polyester compound with a specific melting point and coefficient of thermal contraction and thermal contraction stress which satisfy specific conditions. CONSTITUTION:Biaxially oriented film is made of 0.5 to 6mum thick polyester at a melting point of 200 to 240 deg.C. It has a coefficient of thermal contraction of 5 to 15% after three minutes of processing at 140 deg.C and a coefficient of thermal contraction of 1.5 to 8% after three minutes of processing at 100 deg.C with a thermal contraction stress in the longitudinal direction of the film of 130 to 800 g/mm<2> at 80 deg.C. Polyester is composed of aromatic carboxylic acid as a main acid component and alkylene glycol as a main glycol. Aromatic dicarboxylic acids used are terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid. Alkylene glycols used are ethylene glycol, trimethylene glycol, tetramethylene glycol, 1,4-cyclohexane dimethanol. |
