Patent ID: 8993075
Filing Date: 2015-03-31
Classification: B29C,B29K,B32B,C09K,G02B,Y10T

Abstract:
1. A process for producing a stretched film comprised of a “B” layer comprised of a methacrylic resin 1, an “A” layer comprised of a styrene-based resin, and a “B 2 ” layer comprised of a methacrylic resin 2, stacked in that order, simultaneously biaxially stretched, and having a width of over 1000 mm, comprising a step of heat fixing at a heating zone arranged at an oven outlet of a simultaneous biaxial stretching apparatus with heat fixing temperature that is lower than stretching temperature and a step of giving takeup tension in a section from the oven outlet to a takeup of the stretched film, wherein the stretching temperature is in a range of 126 to 134° C., wherein a ratio of the “A” layer in said stretched film is 45 wt % or less, an average value of an orientation angle θ with respect to a width direction across at least 1000 mm of the width direction is 0°±1°, a variation in the orientation angle θ is 0.5° or less, an average value of an Nz coefficient is −3.5 to −0.5 in range, and an average value of an in-plane direction retardation Re of the “A” layer that is measured by light having a wavelength of 400-700 nm is 30 nm to 70 nm, wherein the takeup tension and the heat fixing temperature are controlled to maintain the variation in the orientation angle θ to be 0.5° or less.