| 摘要 |
A process for injection compression molding ultra high molecular weight polyethylene having an intrinsic viscosity of 3 dl/g or higher measured at 135 DEG C. in decalin and a melt index of 0.01 g/10 min or less comprises, (a) heating the ultra high molecular weight polyethylene to 170 DEG -240 DEG C., (b) adjusting the volume of the mold cavity V1 equal to the volume of the molded article V0, (c) injecting ultra high molecular weight polyethylene having a volume V0 into the mold cavity through a runner portion at a shear rate of at least 20,000 sec-1, (d) instantaneously expanding the mold cavity to adjust its volume V1 to satisfy the relation: 1.2 V0</=V1 at a time from T1 (immediately before completion of injection) and a time T2 (after completion of injection while there is a pressure difference between the cavity and the runner portion, and the ultra high molecular weight polyethylene in the runner portion being solidified), and (e) compressing the volume of the mold cavity V1 to satisfy the relation: V1=V0 while the ultra high molecular weight polyethylene in the mold cavity is still in a molten state. |
