Patent ID: 7276463

Claim:
A catalyst for polymerizing α-olefin, comprising a combination of: a component (A) that is a solid catalyst component comprising magnesium, titanium, and a halogen as an essential component; a component (B) that is an organoaluminum compound; a component (C) that is a compound comprising a C(═O)N bond selected from the group consisting of tetramethylurea, tetraethylurea, bis(tetramethylene)urea, N,N′dimethyl-N,N′-diphenylurea, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, N,N-dimethylpropionamide, 1,3-diacetyl-2-imidazolidinone, 1-methyl-2-pyrrolidinone, 1-ethyl-2-pyrrolidinone, 1-dodecyl-2-pyrrolidinone, 1-cyclohexyl-2-pyrrolidinone, 1-phenyl-2-pyrrolidinone, and N-methyl-ε-caprolactam; and a component (D) that is a silicon compound or a compound having at least 2 ether bonds.