| 摘要 |
<p>Thermoplastic rubbers comprising propylene-ethylene copolymers containing more than 20% and up to 50% by weight of copolymerized ethylene and showing, on X-rays examination in the unoriented state, crystallinity of the polypropylene and/or polyethylene type are disclosed. Also disclosed is a method for preparing the thermoplastic rubbers by polymerizing mixtures of propylene and ethylene in the presence of a catalyst obtained by reacting. (A) a catalyst-forming component which is (a) an addition and/or substitution product of an electron-donor compound (or a Lewis base) with an Al-trialkyl compound, or (b) the addition reaction product of an electron-donor compound with an Al-alkyl compound containing two or more aluminum atoms bound to each other through an oxygen or nitrogen atom, component (A) being further characterized in that it is prepared by reacting 1.0 mole of an Al-alkyl compound with 0.1 - 1.0 mole of a Lewis base which is an ester of an organic or inorganic oxygenated acid, a polyamine compound, or any Lewis base other than said esters and polyamine compounds, provided that, in the latter case, component (B) of the catalyst is a complex of a halogenated titanium compound with a polyamine; and (B) a catalyst-forming component which is the product obtained by contacting an addition compound of a di-, tri-, or tetravalent titanium compound and an electrondonor compound with a carrier consisting of or comprising an anhydrous magnesium dihalide, component (B) being further characterized in that, in its X-rays powder spectrum, a halo appears in place of the most intense diffraction line characteristic of the X-rays powder spectrum of the normal, non-activated magnesium dihalide and, furthermore, in that the amount of Ti compound contained in component (B) and expressed as Ti, is less than 0.3 g. per mole of the total amount of the electron-donor compound used in preparing the catalyst and in that the molar ratio of said Ti compound to the Al-alkyl compound is comprised between 0.001 and 0.1.</p> |
