The invention comprises an olefin polymerization process comprising contacting ethylene alone or with one or more olefinically unsaturated comonomers with a Group 3-6 metallocene catalyst compound comprising one π-bonded ring having a C
3
or greater hydrocarbyl, hydrocarbylsilyl or hydrocarbylgermyl substituent said substituent bonded to the ring through a primary carbon atom; and, where the compound contains two π-bonded rings, the total number of substituents on the rings is equal to a number from 3 to 10, said rings being asymmetrically substituted where the number of substituents is 3 or 4. The invention process is particularly suitable for preparing ethylene copolymers having an MIR less than about 35, while retaining narrow CD even at high comonomer incorporation rates, and with certain embodiments providing ethylene copolymers having improved melt strength with the low MIR.
本发明包括一种烯烃聚合工艺,该工艺包括将
乙烯单独或与一种或多种烯烃不饱和共聚单体与 3-6 族茂
金属催化剂化合物接触,该催化剂化合物包含一个具有 C
3
或更大的烃基、烃基
硅基或烃基革基取代基,所述取代基通过一个主碳原子键合到环上;如果化合物含有两个π键合环,则环上取代基的总数等于3至10,当取代基数为3或4时,所述环被不对称取代。本发明工艺特别适用于制备 MIR 小于约 35 的
乙烯共聚物,同时即使在高共聚单体掺入率下也能保持窄 CD,在某些实施例中,本发明工艺提供的
乙烯共聚物在低 MIR 的情况下具有更高的熔体强度。