| 摘要 |
PURPOSE:To obtain dimensionally stable products that have no air babbles nor fisheyes with high productivity (low required motor power per amount discharged) and with uniform discharge rate, by utilizing a specially constructed screw. CONSTITUTION:A screw whose optimum compression ratio is 2.8 to 6.0 and clearance to a barrel is 0.2 to 2.0mm, is constructed in such a way that length of a compressing section is 14 to 25% of the sum of length of supplying section, compressing section, and weight measuring section. By utilizing this screw, a vinyl alcohol copolymer is extruded or injection molded. A saponified copolymer of ethylene and vinyl acetate consisting of 15 to 55 mole% of ethylene and 80 or more mole% of vinyl acetate saponification rate, is used for instance as a vinyl alcohol copolymer. |
