ETHYLENE COPOLYMER HAVING MULTIPLE PITCH IN MOLECULAR WEIGHT DISTRIBUTION AND THE METHOD OF PREPARING THE SAME

摘要

An ethylene copolymer is provided to ensure multiple pitch in molecular weight distribution and comonomer distribution, and excellent properties and processability and to enhance product value and product quality of a pipe and film. A method for manufacturing an ethylene copolymer having multiple pitch in molecular weight distribution comprises (a) a step for preparing the first copolymer solution by polymerizing ethylene and one or more C4~C10 alpha-olefin by using a metallocene catalyst of the formula 1 which comprises an aryloxide ligand substituted with a cyclopentadiene derivative surrounding the transition metal and an aryl derivative at an ortho-position and is not cross-linked between ligands, in the first reactor; (b) a step for manufacturing the second copolymer solution by passing the first copolymer solution through the second reactor containing the same metallocene catalyst, ethylene and one or more C4~C10 alpha-olefin as the step (a) at a temperature higher than the reaction temperature of (a) step; and (c) a step for manufacturing the third copolymer solution by passing the second copolymer solution through the third reactor containing a Ziegler-Natta catalyst different from the catalyst used in (a) and (b) step, ethylene and one or more C4~C10 alpha-olefin at a temperature higher than the reaction temperature condition of (b) step.