SUCCESSIVELY BIAXIALLY STRETCHED POLYGLYCOLIC ACID FILM, PROCESS FOR PRODUCING THE SUCCESSIVELY BIAXIALLY STRETCHED POLYGLYCOLIC ACID FILM, AND MULTILAYERED FILM

摘要

Disclosed is a process for producing a successively biaxially stretched polyglycolic acid film comprising a step (1) of unidirectionally stretching an amorphous polyglycolic acid sheet at a stretching temperature of 40 to 70°C and at a primary stretch ratio of 2.5 to 7.0 to form a uniaxially stretched film, a step (2) of passing the uniaxially stretched film through an environment having a temperature which is in a range of 5 to 40°C and is at least 5°C below the stretching temperature of the step (1), a step (3) of stretching the uniaxially stretched film in a transverse direction transversely to the stretching direction in the step (1) at a stretching temperature, which is in a range of 35 to 60°C and is at least 3°C above the temperature adopted in the step (2), to form a biaxially stretched film having an area ratio of 11 to 30, and a step (4) of heat treating the biaxially stretched film at 70 to 200°C.