| 摘要 |
PURPOSE:To eliminate the generation of a sink, warpage or the like, to improve appearance quality, rigidity, heat resistance or the like and to enhance surface impact strength by injecting and compressing polypropylene of which the intrinsic viscosity measured in tetralin is within a definite range. CONSTITUTION:Polypropylene of which the intrinsic viscosity measured in tetralin at 135 deg.C is 2.0-12.0dl/g is injected and compressed. When the intrinsic viscosity is below 2.0dl/g, mechanical characteristics are not developed and, when the intrinsic viscosity is 12.0dl/g or more, a molded product having good appearance quality is not obtained. As polypropylene to be used, a propylene homopolymer or a random or block copolymer of propylene and alpha-olefin such as ethylene, 1-butene or 1-hexene is designated. Polypropylene is produced by a known method using a Ziegler type polymerization catalyst or an improved catalyst thereof. |
