Patent ID: 7749412
Filing Date: 2010-07-06
Classification: B29C,B29D,B29K,C09K,G02B,Y10T

Abstract:
1. A method for producing an optical film comprising a cycloolefin resin or a cellulose ester resin comprising the steps of: (i) melt casting or solution casting a cycloolefin resin or a cellulose ester resin on a rotary drum support or on a rotary endless belt support to form a cast film; (ii) peeling the cast film from the support to form a peeled film; (iii) stretching the peeled film to form a stretched film; (iv) drying the stretched film; (v) slitting at least one of two edges of the stretched film; and (vi) winding the stretched film in a roll, wherein (a) a stretching factor of the peeled film is 1.05-1.3 in both the machine direction and the transverse direction; (b) a residual solvent content in the stretched film is 0.5% or less by weight in the slitting step; (c) a width of the stretched film after slitting is 1400 mm or more; and (d) an average surface roughness Ra specified in JISB0601-2001 of a cross-section of the at least one slit edge of the stretched film formed by slitting is 0.05 to 0.9 μm.