Abstract: Disclosed is a biaxially oriented polyester film that is excellent in adhesiveness with a metal layer etc., and excellent in deep drawability for an isotropic chape, such as a square shape. A biaxially oriented polyester film having at least a base layer and an adhesive layer each of which contains a polyester as a main component, the film satisfying the following requirements (1) to (3): (1) a difference between reversible heat capacity difference (?Cp) at around glass transition temperatures of the adhesive layer and the base layer is not smaller than 0.10 and not larger than 0.45; (2) a molecular orientation ratio measured by using a molecular orientation meter is higher than 1.2; and (3) a stress at 10% elongation (F10) in each of a machine and transverse direction is not lower than 90 MPa and not higher than 160 MPa.

Abstract: Disclosed is a biaxially oriented polyester film that is excellent in adhesiveness with a metal layer etc. and excellent in deep drawability for an isotropic shape, such as a square shape. A biaxially oriented polyester film having at least a base layer and an adhesive layer each of which contains a polyester as a main component, the film satisfying the following requirements (1) to (3): (1) a difference between reversible heat capacity difference (?Cp) at around glass transition temperatures of the adhesive layer and the base layer is not smaller than 0.10 and not larger than 0.45; (2) a molecular orientation ratio measured by using a molecular orientation meter is not lower than 1.0 and not higher than 1.2; and (3) a stress at 10% elongation (F10) in each of a machine and transverse direction is not lower than 90 MPa and not higher than 160 MPa.

Abstract: To provide a polyester film that has excellent pinhole resistance and bag breakage resistance, excellent adhesiveness after boiling or retorting, and little pitch deviation during printing or position deviation during laminating with a sealant, etc. A biaxially oriented polyester film simultaneously fulfilling (a)-(d). (a) Being a polyester resin composition containing 60%-90% by weight polybutylene teraphthalate resin (A) and 10%-40% by weight of a polyester resin (B) other than the polybutylene teraphthalate resin (A). (b) Having a transesterification ratio of 0.8-3.0 for the film. (c) Having a degree of orientation ?Nx in the film longitudinal direction of 0.049-0.076. (d) Having a thermal shrinkage at 150° C. of no more than 4.0% in both the longitudinal and width directions of the film.

Abstract: To obtain a polyester film that has excellent pinhole resistance and bag breakage resistance, excellent adhesiveness after boiling or retorting, and little pitch deviation during printing or position deviation during laminating with a sealant, etc. A biaxially oriented polyester film simultaneously fulfilling (a)-(d). (a) Being a polyester resin composition containing 60%-90% by weight polybutylene teraphthalate resin (A) and 10%-40% by weight of a polyester resin (B) other than the polybutylene teraphthalate resin (A). (b) Having a dimensional change rate at 80° C. of no more than 1.0% in the longitudinal direction of the film, relative to a film base length of a temperature dimensional change curve measured using a thermal mechanical analyzer. (c) Having a thermal shrinkage at 150° C. of no more than 4.0% in both the longitudinal and width directions of the film. (d) Having a film plane orientation ?P of 0.136-0.154.

Abstract: The invention provides a biaxially oriented polyester film that is suitable for a food packaging material subjected to a boiling sterilization treatment or a retort sterilization treatment, has excellent impact resistance, bending resistance and uniform mechanical properties and, simultaneously, renders an oligomer component contained in the film less likely to be eluted. The biaxially oriented polyester film has the following characteristics: (a) the film comprises a resin composition containing 60 mass % or more of polybutylene terephthalate; (b) a thickness precision in a widthwise direction of the film is 1 to 20% or less; (c) an oligomer component contained in the film is 2000 to 12000 ppm; and (d) a mass of the oligomer component eluted into a 50% ethanol solution is 0.02 mg or less per square inch of the film when the film is immersed in the 50% ethanol solution and heated at 66° C. for 2 hours.