Manufacturing method for propylene block copolymer

A method for producing a propylene-based block copolymer comprising:

• a first step of homopolymerizing propylene during which an electron donor compound (IV) is added to form a propylene homopolymer by bringing an olefin polymerization catalyst into contact with propylene;
• subsequent to the first step, a second step of copolymerizing propylene and an α-olefin other than propylene in the presence of the olefin polymerization catalyst and the propylene homopolymer;
• the olefin polymerization catalyst comprising a solid catalyst component for olefin polymerization that comprises titanium, magnesium, a halogen, and an internal electron donor compound, an organoaluminum compound represented by a general formula (I), and an external electron donor compound represented by a general formula (II) or an external electron donor compound represented by a general formula (III),
• R1pAlQ3-p (I)
• wherein R1 is a hydrocarbyl group having 1 to 6 carbon atoms, p is a real number that satisfies 0<p≤3, provided that a plurality of R1 are either identical to or different from each other when a plurality of R1 are present, and Q is a hydrogen atom,
• a hydrocarbyloxy group having 1 to 6 carbon atoms, or a halogen atom, provided that
• a plurality of Q are either identical to or different from each other when a plurality of Q are present,
• R2Si(OR3)3 (II)
• wherein R2 is a hydrogen atom, a linear alkyl group having 1 to 20 carbon atoms,
• a branched alkyl group having 3 to 20 carbon atoms, a vinyl group, an allyl group,
• a linear or branched alkenyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms,
• an aromatic hydrocarbon group having 6 to 24 carbon atoms, a nitrogen atom-containing hydrocarbon group having 2 to 24 carbon atoms that is terminated by a carbon atom, or an amino group having 2 to 24 carbon atoms, and R3 is a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, a vinyl group, an allyl group, a linear or branched alkenyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 24 carbon atoms, provided that the three R3 are either identical to or different from each other,
• (R4R5N)Si(OR6)3 (III)
• wherein R4 and R5 are a hydrogen atom, a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, a vinyl group, an allyl group, a linear or branched alkenyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 24 carbon atoms, a nitrogen atom-containing hydrocarbon group having 2 to 24 carbon atoms that is terminated by a carbon atom, or an amino group having 2 to 24 carbon atoms, provided that R4 and R5 are either identical to or different from each other, and are optionally bonded to each other to form a ring, and R6 is a linear alkyl group having 1 to 20 carbon atoms,
• a branched alkyl group having 3 to 20 carbon atoms, a vinyl group, an allyl group,
• a linear or branched alkenyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, or
• an aromatic hydrocarbon group having 6 to 24 carbon atoms, provided that the three R6 are either identical to or different from each other, and
• wherein the electron donor compound (IV) is an alcohol.