Decurling method and apparatus, and film production method

A film production method for a continuous multi-layer film having at least first and second layers and having a curling tendency to direct said first layer inwards, comprising step of:

• moving said multi-layer film longitudinally;
• during movement of said multi-layer film, supplying water vapor to contact a surface layer portion in said second layer, to apply heat to set said surface layer portion at a higher temperature than a glass transition temperature thereof;
• during movement of said multi-layer film and immediately after said vapor supply step, cooling said multi-layer film of which said surface layer portion is set at said higher temperature, so as to set temperature of said multi-layer film at 50 deg. C. or lower within 2 seconds from a start thereof.

A decurling apparatus for a continuous multi-layer film having at least first and second layers and having a curling tendency to direct said first layer inwards, comprising:

• a cover body for covering a moving path through which said multi-layer film is moved longitudinally;
• a water vapor source, contained in said cover body, for supplying water vapor to contact a surface layer portion in said second layer, to apply heat to set said surface layer portion at a higher temperature than a glass transition temperature thereof;
• a cooling device, contained in said cover body, disposed downstream of said water vapor source adjacently, for cooling said multi-layer film of which said surface layer portion is set at said higher temperature, so as to set temperature of said multi-layer film at 50 deg. C. or lower within 2 seconds from a start thereof.