| 摘要 |
PURPOSE: To obtain a method for injection compression molding polypropylene without sinkmarks, warpage, and the like with a good appearance quality, superior rigidity and mechanical characteristics, such as a heat resistance, and esp. an improved face impact strength. CONSTITUTION: Polypropylene having an ultimate viscosity of 2.0-12.0dl/g measured in 135 deg.C tetralin is injected into a mold having a space of a thickness that is 1.2-2.0 times larger than a thickness of a final molded piece at a shear speed of 10000-50000sec<-1> at a nozzle part. When 60-90% of the total polypropylene injection amount is injected, mold closing is started. When the injected polypropylene is cooled to a temperature of 130-180 deg.C, mold closing is completed. In this manner, the polypropylene is injection compression molded. |
