To provide an optical film and its manufacturing method wherein a wide optical film is smoothly manufactured with a touch roll system without making thick film parts at the film end part in the width direction in a step of extruding a resin molten material and by making the thick film parts in another step, a stretching condition of the film end part does not become nonuniform by increasing the thickness of the film end part held by a clip when TD stretching the film in the width direction by a tenter, the yield rate is improved, and a manufacturing cost can be reduced.
In the manufacturing method of the optical film by a melt-casting film forming method, an unstretched film is MD-stretched by 1.01 to 3.0 times at the substantial stretching span of 50 mm to 300 mm in an MD stretching step, to form the thick film part (projection part) at the both ends parts in the film width direction, and then the film is TD stretched by 1.1 to 3.1 times in the width direction by holding the thick film part at the both ends parts in the film width direction in a TD stretching step.
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Einosuke Kishimoto
Akira Watanabe
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