Optical film, shaping film, method for manufacturing optical film, and method for manufacturing stretched film

A method for producing a trimmed film, comprising the steps of:

• producing an optical film containing an additive;
• and,
• cutting off both end portions in a width direction of the optical film;
• wherein
• the optical film comprises a high concentration portion containing the additive;
• a low concentration portion containing the additive at a concentration lower than the high concentration portion;
• and boundary portions between the high concentration portion and the low concentration portion,
• the low concentration portion is provided on both sides of the high concentration portion in a thickness direction of the optical film,
• the low concentration portion is provided on both sides of the high concentration portion in the width direction of the optical film, and
• the boundary portions are provided with the end portions on both sides of the high concentration portion in the width direction of the optical film, wherein
• the step of cutting both end portions in the width direction of the optical film comprises cutting off the boundary portions from the optical film to form end surfaces on which the high concentration portion is exposed, and
• wherein the optical film has a region where the high concentration portion has a thickness of “average thickness of the high concentration portion ±5 μm” in a continuous section having a length of 500 mm or more in the width direction of the optical film.