| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-cost isotropic sheet for optical use having no surface defect, optical isotropy, advanced gas barrier performance, high wear resistance, excellent conductivity, uniform in a quality and a method for manufacturing the same. SOLUTION: The isotropic sheet for optical use is 5 nm or less in retardation(Rd), 160 deg.C or higher in glass transition temperature, and 200μor more in thickness, and is manufactured by the melt extrusion of a laminated sheet BAB, wherein a polymer layer B is attached to both sides of an optical isotropic sheet-constituting polymeric resin layer A with the layers B peelable from the layer A, with the laminated sheet BAB to be closely attached to a cooling drum upon melt extrusion. In this method, the glass transition temperature Tgb of the layer B should be not lower than the glass transition temperature of the layer A (Tga-70) deg.C in the laminated sheet and the laminated sheet should be attached closely to the drum with its temperature kept at between (Tgb-50) deg.C or higher and (Tgb+30) deg.C or lower.
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