| 摘要 |
PURPOSE: To prepare a white polyester film which has high cushioning properties, is flexible and excellent in printability, and hardly creases or does not noticeably crease by selecting a white polyester film having specified physical properties. CONSTITUTION: A white polyester film is selected which has an apparent density lower than 1.2g/cm<3> and a crease index of 1.5 or lower. The film pref. has a cleavage strength of 250g/15mm or higher and still pref. a glossiness lower than 10%. Such a film is obtd. by bonding a film formed by extruding a molten mixture comprising polyethylene terephthalate, poly-4-methylpentene-1 which is incompatible therewith, and polyethylene glycol as a density-lowering agent to a film formed by extruding a melt of polyethylene terephthalate contg. CaCO3 on a cooling drum by the static charge method. |
