| 摘要 |
An optical film of high planarity that even in the use of an optical film material containing a non-resinous additive in an amount of 5 mass % or more, would exhibit inexpensive satisfactory roll cleaning effects, and that would find application in, especially, various functional films such as a retardation film and a protective film for polarization plate for use in a liquid crystal display apparatus, etc.; and a process for producing the optical film. There is disclosed a process for producing an optical film according to a melting casting film forming method, including extruding a melt of resin blend containing a resin and 5 mass % or more of non-resinous additive through a casting die into a film form, wherein a first roller (5) for cooling has a temperature of the melting point of the additive to the glass transition temperature (Tg) of the resin blend. Preferably, the first roller (5) for cooling has a peripheral speed (S1) exhibiting a ratio between the same and the peripheral speed (S3) of a third roller (7) for cooling, S3/S1, of 1.001 to 1.05. Preferably, a filmlike molten blend is pressed against the first roller (5) for cooling at a linear pressure of 0.5 to 50 N/mm by means of a second roller (6) for pressure application.
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