| 摘要 |
Polymers of polypropylene are prepared by means of a Ziegler-Natta catalyst system comprising (1) a titanium component which contains titanium, magnesium, chlorine and a benzenecarboxylic acid derivative, (2) an aluminum component and (3) a silane component, wherein the (1) used is obtained by (1.1) first reacting with one another (1.1.1) in a liquid hydrocarbon, (1.1.2) a finely divided magnesium halide, (1.1.3) an alkanol, (1.1.4) a phthalic acid ester and (1.1.5) titanium tetrachloride under certain conditions, (1.2) then extracting the solid intermediate obtained from (1.1) with titanium tetrachloride until the remaining solid substance has become significantly richer in magnesium, and (1.3) finally washing the solid substance remaining in (1.2) with an alkane in a certain manner.
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