Biaxially oriented copolyester film and laminates thereof

Abstract

Disclosed is a biaxially-oriented polyester film produced from a polyester comprising: (1) diacid residues comprising between about 95 and about 100 mole percent of terephthalic acid residues; (2) diol residues comprising between about 95 and about 100 mole percent of 1,4-cyclohexanedimethanol residues; and (3) about 0.5 to about 5 mole percent of another dicarboxylic acid or diol residue, wherein the polyester comprises a total of 100 mole percent diacid residues and a total of 100 mole percent diol residues. In one embodiment, the biaxially-oriented film has a thickness of 70 to 150 microns (3-5 mils). In another embodiment, the biaxially-oriented film undergoes not more than 3% shrinkage when immersed for 10 seconds in a solder bath preheated to 260° C. The film can be made by stretching an essentially amorphous cast film of thickness between about 450-1800 micron (18-70 mil) at a ratio from about 2.5×2.5 to 3.5×3.5 while being held at a temperature between 90° C. and 130° C., and heat-setting the stretched film at an actual film temperature of from 260° C. to Tm, where Tm is the melting point of the polyester as measured by differential scanning calorimetry (DSC), while maintaining the dimensions of the stretched film.