| abstract |
PURPOSE: To obtain the title film of excellent abrasion resistance, containing specified particles. n CONSTITUTION: 1W15wt.%, based on particles, dispersant such as triethylammonium phosphate is added to a slurry obtained by adding particles of an average particle diameter of 0.05W2.0μm and a Mohs' hardness of 7W10 (e.g., particles of TiN) to ethylene glycol and boiling the obtained mixture for 12W48hr. The resulting ethylene glycol and dimethyl terephthalate are subjected to transesterification and subsequent polycondensation to obtain a polyester of an intrinsic viscosity of 0.60W0.93. An unoriented film obtained by melt-extruding this polyester is stretched in the machine direction at a stretch ratio of 3.0W4.0 and a temperature from the glass transition point of the polymer to its cold crystallization temperature, stretched in the crosswise direction at a stretch ratio of 3.2W4.5 and a temperature form the glass transition temperature plus 10°C to the cold crystallization temperature plus 10°C and heat-treated at 180W250°C for 0.5W60sec to obtain a biaxially oriented polyester film of a film skin thickness of 100W300Å as measured with a secondary ion mass spectrograph and a surface protrusion peak of 0.02W0.50. n COPYRIGHT: (C)1988,JPO&Japio |