| 摘要 |
<p>PURPOSE:To make it possible to perform stably the biaxial orientation of a polyester film and to eliminate a difference in the properties between its face and rear by adding BaSO4 and a metal salt of a fatty acid to the film. CONSTITUTION:1-50wt.% BaSO4 particles of a mean particle diameter of 0.1-10mum and 0.005-0.05mol, per mol of BaSO4, of a metal salt of a fatty acid of an m.p. of 120-320 deg.C (e.g. barium stearate) are added to a polyester (e.g. polyethylene terephthalate), and the obtained mixture is melt-extruded through a die and solidified by rapidly cooling the extrudate on a casting drum preset at 20-40 deg.C to obtain an oriented film of a thickness >=1mm. This film is uniaxially oriented in a draw ratio of 1.5-4.5 at a temperature higher than the glass transition temperature of the polyester by 20-70 deg.C and further oriented at a draw ratio of 1.5-4.5 and an areal draw ratio of 6-15 in the direction perpendicular to the direction of the initial orientation and heat-set at a temperature lower than the m.p. of the polyester by 15-100 deg.C to obtain a biaxially oriented polyester film of a thickness >=100mum.</p> |
