Patent ID: 8158218

Claim:
A method for producing an optical film by laminating a cellulose ester resin layer (A) and an acrylic resin layer (B) comprising: coextruding a melt composition of a cellulose ester resin and a melt composition of an acrylic resin, wherein the cellulose ester resin layer (A) contains 55 to 99% by mass of a cellulose ester resin, and 1 to 45% by mass of an acrylic resin, wherein total content of the cellulose ester resin and the acrylic resin is 100% by mass, the acrylic resin layer (B) contains 55 to 99% by mass of an acrylic resin, and 1 to 45% by mass of a cellulose ester resin, wherein total content of the cellulose ester resin and the acrylic resin is 100% by mass; and conveying coextruded web while cooling by a first cooling roll and a second cooling roll arranged subsequent to the first cooling roll, wherein the coextruded web is conveyed while the cellulose ester resin layer (A) being in contact with a surface of the first cooling roll, and the acrylic resin layer (B) being in contact with a surface of the second cooling roll, and Ta (° C.) and Tb (° C.) satisfy the following relation 1, wherein Ta (° C.) is a surface temperature of the first cooling roll, and Tb (° C.) is a surface temperature of the second cooling roll, ( Ta− 80)° C.< Tb (° C.)<( Ta− 5)° C., Relation 1 wherein a weight average molecular weight of the cellulose ester resin of the acrylic resin layer (B) is 100,000 to 400,000.