| 摘要 |
PURPOSE:To obtain a propylene-ethylene block copolymer which has a low powder-adhesive power and a good particle fluidity in addition to high activity and stereoregularity. CONSTITUTION:This copolymer is produced by a polymn. process carried out in the presence of a catalyst comprising a solid catalyst component (A) essentially contg. Mg, Ti, a halogen, and an electron-donating compd., an organoaluminum compd. (B), and an electron-donating compd. (C). The process comprises two or more steps: the first step wherein a propylene polymer is produced by the polymn. under the condition that the propylene concn. in the gas phase is 90mol% or higher, and the second and later steps wherein propylene and ethylene are copolymerized in the presence of the polymer produced at the former step under the condition that the propylene concn. in the gas phase is lower than 90mol%. In the above process, at least one alkoxysilane compd. is used as electron-donating compd. C and an ether compd. is supplied newly as another electron-donating compd. (D) at the second step or later. |
