Abstract: The present invention relates to a polyethylene-2,6-naphthalate film comprising a resin composed mainly of polyethylene-2,6-naphthalate and having an intrinsic viscosity .eta. in the range of from 0.31 to 0.6, said film having stretch ratios of 1 to 3 times and 1 to 3 times or 3 to 6 times and 1 to 1.8 times respectively in substantially mutually perpendicular directions and a thickness in the range of from 5 to 150 .mu.m;a polyethylene-2,6-naphthalate resin comprising a blend composed mainly of two components of: a polyethylene-2,6-naphthalate resin having an intrinsic viscosity in the range of from 0.3 to 0.5 dl/g and prepared by an esterification reaction of a dicarboxylic acid having a 2,6-naphthalenedicarboxylic acid content of not less than 90% by mole with a glycol having an ethylene glycol content of not less than 90% by mole, or a transesterification and a polyethylene-2,6-naphthalate resin having an intrinsic viscosity in the range of from 0.5 to 0.

Abstract: Packaging films for press-through packaging comprise a polyethylene-2,6-naphthalate film having an intrinsic viscosity .eta. of 0.31 to 0.6 wherein the film is: (1) stretched in mutually perpendicular directions each with draw ratios of 1 to 3 times; or (2) stretched in the longitudinal direction at draw ratios of 3 to 6 times and in the transverse direction at draw ratios of 1 to 1.8 times. The films have a thickness of 5-150 .mu.m and may be incorporated into multi-layer cover films comprising the polyethylene-2,6-naphthalate film, a barrier layer, a reinforcing layer, and a sealing or adhesive layer.