PVA BASED FILM AND OPTICAL FILM

摘要

PURPOSE:To provide a PVA (polyvinylalcohol) based film having an excellent optical homogeneity, a PVA based polarizing film and a PVA based phase difference film. CONSTITUTION:The PVA based film having a <=1.0X10<-3> average double refractive index (DELTAn) and a <=0.13X10<-3> double refractive index variation (Rn), preferably has a 20 to 100mum average 'thickness (t) and a <=3% thickness variation (Rt). The polarizing film using the PVA based film has a <=0.5 % monochromatic transmittance variation (Ry) and a <=2.5 dichroism ratio variation (DELTARd). The phase difference film using the PVA based film has a <=2% phase difference variation (Re).