Process for forming a polyester film

Abstract

A polyester film, which is substantially non-oriented and whose main component is polyethylene terephthalate, is formed into a shape for example, a package, at a condition causing no yield point. The formation ability of the polyester film for forming is improved, and a formed body having a good uniformity in thickness can be obtained. Further, the range of the temperature condition causing no yield point can be enlarged by laminating a PET-system polyester, which originally tends to cause a yield point by itself, onto a polyester having no yield point. In such a laminated polyester film, the slipping property and releasing property from a mold of the film can be improved by specifying the ranges of the degree of crystallinity of each layer, the adhesive force at a high temperature of the film and the surface roughness of the film, and the shape of a formed body can be improved.

Dependencies are inferred from the claim text.