초록 ▼

A process for injection compression molding ultra high molecular weight polyethylene having an intrinsic viscosity of 3 dl/g or higher measured at 135°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°-240°C., (b) adjus

A process for injection compression molding ultra high molecular weight polyethylene having an intrinsic viscosity of 3 dl/g or higher measured at 135°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°-240°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.

대표청구항 ▼

A process for injection compression molding ultra high molecular weight ployethylene having an intrinsic viscosity of at least 3 dl/g measured at 135°C. in decalin and a melt index of up to 0.01 g/10 min which comprises, (a) heating ultra high molecular weight polyethylene to 170°-240°C., (b) adjust

A process for injection compression molding ultra high molecular weight ployethylene having an intrinsic viscosity of at least 3 dl/g measured at 135°C. in decalin and a melt index of up to 0.01 g/10 min which comprises, (a) heating ultra high molecular weight polyethylene to 170°-240°C., (b) adjusting the volume of the mold cavity V1 in a mold at a mold temperature of from 80°C. to 120°C. to be equal to the volume of the molded article V0, (c) injecting ultra high molecular weight polyethylene having volume V0 into the molded 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 time T2 while there is a pressure difference between the cavity and the runner portion, and the ultra high molecular weight polyethylene in the runner portion has not solidified, and (e) compressing the volume of the mold cavity V1 to satisfy the relation: V1=V0 while the ultra high molecular weight polyethlene in the mold cavity is still in a molten state.