| 摘要 |
The present invention contains an ethylene-modified PVA polymer having favorable stretching characteristics and production characteristics and having an ethylene unit content of 1-4 mol%, and satisfies the belowmentioned formulas (I) and (II): Deltan(MD)Ave-0.1×10-3 <= Deltan(TD)Ave <= Deltan(MD)Ave+0.25×10-3 (I) and Deltan(TD)Ave <= 2.5×10-3 (II) (in the abovementioned formulae: Deltan(MD)Ave indicates value of the birefringence in the direction of machine flow of ethylene-modified PVA polymer film averaged in the thickness direction of the film; and Deltan(TD)Ave indicates the value of the birefringence in the widthwise direction of the ethylene-modified PVA polymer film averaged in the thickness direction of the film). |
