BIAXIAL ORIENTED POLYETHYLENE NAPHTHALATE FILM HAVING IMPROVED TRANSPARENCY

摘要

PURPOSE: A polyethylene naphthalate biaxially oriented film is provided to have excellent dimensional stability in high temperatures, and to improve light transmittance, thereby capable of being used as a touch panel, a substrate material for a flexible display, etc. CONSTITUTION: A polyethylene naphthalate biaxially oriented film is manufactured from polyethylene naphthalate containing 50-2500 ppm of a polyfunctional compound having trivalent or polyvalent reactive group. The polyfunctional compound having trivalent or polyvalent reactive group is a compound having a trivalent or polyvalent acid component or trivalent or a polyvalent alcohol component. The polyethylene naphthalate has color index L value of 45-65, and b value of 0-10. The film is elongated toward longitudinal direction by 2.5-3.5 times, and toward transversal direction by 3.3-4.5 times.