| 摘要 |
FIELD: chemistry.SUBSTANCE: ethylene copolymers and a method of producing said copolymers are provided. More specifically, provided are ethylene copolymers which exhibit excellent processability and physical properties due to their polydispersity index of polymodal molecular weight distribution, achieved via a multi-step process using reactors which are connected in series or in parallel. The method involves: a) solution polymerisation of ethylene and C3-C18 ?-olefin comonomer(s) in the presence of a catalyst composition containing a transition metal catalyst of chemical formula(1) and a cocatalyst; (b) passing a first copolymer synthesised at step (a) through at least another reactor containing ethylene or ethylene and at least one C3-C18 ?-olefin, at temperature 90-220°C and pressure 20-500, at temperature higher than the reaction temperature at step (a) in the presence of the same catalyst composition as was used at step (a) to obtain a polymer at high temperature, which contains a copolymer combination of ethylene and C3-C18 ?-olefin. In the second version of the method, copolymers from step (a) and (b) are obtained separately and (c) the first copolymer from step (a) is mixed with the second copolymer from step (b).EFFECT: disclosed is an ethylene copolymer for making extrusion blown films, films made by casting, articles made by injection moulding, articles made by blow moulding or tubes made using said methods, wherein radicals and symbols assume values given in the claim.14 cl, 3 dwg 4 tbl, 11 ex |
