| 摘要 |
PURPOSE:To manufacture a high strength.high elastic modulus PVA film by using a solvent constituted of a mixture of water and an organic solvent by a certain ratio for gelling the film. CONSTITUTION:A gelled film is discharged out of PVA dissolved in a mixed solvent constituted of water and an organic solvent at the ratio of 90:10-10:90 by the dry, the wet or the dry and wet method, and desolvated, dried, oriented and heat treated. The PVA to be used should preferably be of 95mol% of gelling. The organic solvent should preferably have affinity with water, and dimethyl sulfoxide is preferred. Discharge should preferably be carried out at 40-60 deg.C of temperature of a slitshaped cap in the dry method, while the temperature around the slit-shaped cap should preferably be 60-90 deg.C for the discharge by the dry and wet method, and the mixed material is extruded into a coagulating bath such as acetone just after the discharge, in which the same is drawn. At that time, the same should preferably be coagulated at the temperature of -20 deg.C or less. A desolvated and dried film is dried and oriented or wet heat oriented in the air preferably of 80-140 deg.C after the discharge, and then double-step oriented (either dry or wet) and heat treated at 180-240 deg.C. |
