Patent ID: 7807760

Claim:
A process for producing an ethylene-α-olefin copolymer which comprises continuously polymerizing ethylene and α-olefin in a solvent in the presence of an olefin polymerization catalyst using a polymerization reaction apparatus comprising two or more tanks of polymerization reactors connected in series, said process including the following first polymerization step and second polymerization step: the first polymerization step of producing in a first tank of the polymerization reactor a polymer component having a Mooney viscosity at 100° C. of 10-300 and containing 45-80% by weight of a monomer unit based on ethylene (with a proviso that total content of the monomer unit based on ethylene and the monomer unit based on α-olefin is assumed to be 100% by weight) under the polymerization conditions of a polymerization temperature of −20-200° C., a polymerization pressure of 0.1-10 MPa, and a flow state being 1.5 or more tanks in the perfect mixing cell model, and the second polymerization step of producing in a second tank of the polymerization reactor a polymer component having a Mooney viscosity at 100° C. of 10-300 and containing 45-80% by weight of a monomer unit based on ethylene (with a proviso that total content of the monomer unit based on ethylene and the monomer unit based on α-olefin is assumed to be 100% by weight) under the polymerization conditions of a polymerization temperature of −20-200° C., a polymerization pressure of 0.1-10 MPa, a flow state being less than 1.5 tank in the perfect mixing cell model, and a ratio (n1/n2) of 1.5 or more in which n1 denotes the number of tanks in the perfect mixing cell model at the first polymerization step and n2 denotes the number of tanks in the perfect mixing cell model at the second polymerization step, wherein a reaction mixture obtained by polymerization in the polymerization reactor at the first polymerization step is continuously fed to the polymerization reactor of the second polymerization step.