POLYMER FILM AND PRODUCING METHOD FOR PRODUCING POLYMER FILM

摘要

A co-casting of plural dopes is made to form a casting film (80) of a multi-layer structure having a base layer and at least one outer layer overlapping to the base layer. A viscosity of the dope forming the outer layer is at most 35 Pa·s. Just after the formation of the casting film (80), a drying air is fed out almost in parallel to the belt (73) from an outlet (82a) directed in the running direction of the belt (73), while a temperature of the drying air is controlled in the range of 70 to 130 degrees centigrade. A heater (84) heats the casting film (83) from a rear side of the belt (73) such that the temperature of a rear surface of the casting film (83) may be controlled in the range of 40 to 80 degrees centigrade. Thus the production speed can be increased and the produced film is excellent in planarity.