POLYESTER FILM AND ENVELOPE

摘要

The embodiments relate to a polyester film, which has a high tensile strength in the transverse direction and a low tensile strength in the longitudinal direction, while satisfying the condition of 0.5

主权项

1. A polyester film, which has a thickness of 5-50 μm, a tensile strength of 5-20 kpsi in the longitudinal direction (MD), a tensile strength of 15-40 kpsi in the transverse direction (TD) substantially perpendicular to the MD, and a light transmittance of 80% or more, wherein the polyester film has been stretched about 1.8-3.5 times in the MD and about 2-6 times in the TD, and wherein A calculated by Equation 1 is greater than 0.5 and less than 6:TS1-TS2TS1=AEquation1 wherein TS1 and TS2 are tensile strengths in the MD and in the TD, respectively.