| 摘要 |
A process is disclosed for preparing ethylene polymers with a molecular weight Mw (weight average) lower than 20,000 g/mole at temperatures in a range from 200 to 280 DEG C and pressures in a range from 1000 to 3500 bars in the presence of a catalyst system. The catalyst system used contains: (A) a non-bridged substituted or unsubstituted biscyclopentadienyl complex; (B) a metal compound of general formula (I) M<1> (R<1>)r (R<2>)s (R<3>)t, in which M<1> is an alkaline, an alkaline earth metal or a metal of the third main group of the periodic table; R<1> is hydrogen, C1-C10-alkyl, C6-C15-aryl, alkylaryl or arylalkyl with 1 to 10 C atoms in the alkyl radical and 6 to 20 C atoms in the aryl radical; R<2> and R<3> independently represent hydrogen, halogen, C1-C10-alkyl, C6-C15-aryl, alkylaryl, arylalkyl or alkoxy with 1 to 10 C atoms in the alkyl radical and 6 to 20 C atoms in the aryl radical; r is an integer from 1 to 3; and s and t are integers from 0 to 2, the sum r+s+t corresponding to the valency of M<1>; and (C) a metallocene ion-forming compound selected in a group which consists of strong, neutral Lewis acids, ionic compounds with lewis acid cations and ionic compounds with Brönsted acids as cations. Components (A), (B) and (C) are mixed together and after at the latest 5 minutes are dosed in the reactor. |
