| 摘要 |
PURPOSE:To mold ultra high molecular weight resin of inferior melt flowability provided with excellent impact-resistance, abrasion-resistance, appearance, homogeneity, by injecting molten thermoplastic resin in powdery state, under the specific condition, opening a mold and then introducing it into a cavity for compressing. CONSTITUTION:Molten thermoplastic resin having inferior melt flowability of ultra high molecular weight PE etc. of e.g.[eta]>=3 dl/g (in 135 deg.C decalin), MI<= 0.01g/min is injected via a runner part 2 at the velocity which makes the molten powder form, preferably at a shearing velocity more than 22,000/sec, 170-240 deg.C into the cavity 3 of the same volume V1 as the volume of the desired molded product. Within a time interval from T1 just before finishing of an injection to T2 when there is pressure difference between the runner part 2 and the cavity 3 after finishing and resin does not solidify at the runner part 2, a mold is instantaneously opened to become more than 1.2 times of the volume V1 of the cavity 3 and the resin of the runner part 2 is introduced in powdered form. Then the cavity 3 is compressed to the volume V1 while the resin is in a melted state. |
