| 摘要 |
PURPOSE:To obtain a polyester film for forming a specific optical density and excellent formability, masking power, whiteness, etc., and useful as tray, blister, etc., for medical, general purpose and food use, etc., by laminating a thermoplastic polyester containing a colorant to a surface of the base film. CONSTITUTION:(A) A thermoplastic polyester such as polybutylene terephthalate and (B) a thermoplastic polyester such as polyethylene terephthalate containing 10wt.% of a colorant such as titanium oxide having an average particle diameter of 0.2mum are melted and extruded with separate extruders at 250 deg.C for the component A and 280 deg.C for the component B. The extrudates are laminated one upon another in a feed block and extruded in the form of a molten film having an A/B/A structure through a T-die. The extruded film is solidified by cooling on a casting drum maintained at 25 deg.C, made to contact with a hot roll of 50 deg.C and wound to obtain the objective forming polyester film having an optical density of >=0.3 and exhibiting excellent formability, masking power, whiteness, etc. |
