Abstract: The present invention relates to a single or multilayer biaxially oriented film having a thickness of ≦12 &mgr;m, in which Ts (TD) is ≧160° C., S 200 (TD) is ≦5%, S 200 (MD) is 2-5%, the shrinkage force ratio Ns 220/Ns 160 is ≧4.5; the film fixing peak is ≧210° C.; the film density is 1.39-1.41 g/cm3, and Ts (TD) is the temperature at which the transverse shrinkage begins, S 200 (TD) is the shrinkage in the transverse direction (in %) at 200° C., S 200 (MD) is the shrinkage in the machine direction (in %) at 200° C., Ns 220 is the shrinkage force (in N) at 220° C. and Ns 160 is the shrinkage force (in N) at 160° C. in the transverse direction. The invention also relates to a method for forming the film.

Abstract: The invention relates to a biaxially oriented polyester film having one or more layers and a thickness of .ltoreq.10 .mu.m, where the mechanical consolidation coefficient MC, given by the following equation, lies within the ranges given below:MC here is .gtoreq.-2, preferably >0 and in particular >0.5, particularly preferably .gtoreq.1, and is .ltoreq.50, preferably .ltoreq.30 and particularly preferably <5 ##EQU1## S200.sub.TD is the transverse shrinkage in % at 200.degree. C. after 15 min.S200MD is the longitudinal shrinkage in % at 200.degree. C. after 15 min.T2% is the temperature in .degree. C. at which the film elongates by 2% under a constant tension of 5 N/mm.sup.2.E.sub.TD is the transverse modulus of elasticity (tensile modulus) at room temperature (21.degree. C.) in N/mm.sup.2.

Abstract: Biaxially oriented films containing at least one layer of polyethylene naphthalate bibenzoate (PENBB) copolyester wherein the copolyester contains from about 60 to about 40 mol % of a first recurring unit of the formula (II). ##STR1## and about 40 to about 60 mol % of a second recurring unit of formula (I). The copolyester preferably contains less than 10 mol % of recurring units derived from terephthalate or other dicarboxylic acids. The films have a total thickness of 0.05-500 .mu.m and may contain inert particles.

Abstract: A copolyester composition comprising poly(ethylene naphthalate bibenzoate) ("PENBB") and 0.001 to 5% by weight of fine silica particles having an average diameter of 0.01 to 3.0 .mu.m. Further, films are made from this copolyester composition.