| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that the intrinsic viscosity IV of a polyester resin, namely the lowering in the strength of a container, is caused by a small amount of moisture contained in pellets and a high temperature required for melt molding, in a process for injection-molding the hollow container. SOLUTION: This polyester resin is characterized in that the intrinsic viscosity ratio of a preform to raw material pellets, namely IV retention, is≥95 %. The preform is obtained by injection-molding the polyester resin pellets from an injection cylinder into a mold at a cylinder set temperature of 265 to 290°C with an injection molding machine in a resin retention time of 70 to 120 sec in the injection cylinder. A container having excellent transparency and excellent strength can be produced without needing to highly adjust IV in a polymerization process because the IV is hardly lowered in a molding process and without causing the increase of production cost. COPYRIGHT: (C)2005,JPO&NCIPI |
