System for producing polyolefin, method of producing polyolefin, and method of producing heterophasic propylene polymer material

A method of producing a heterophasic propylene polymer material with use of a system for producing a polyolefin, the system comprising:

• a cylindrical member which extends in a vertical direction;
• diameter decreasing members each of which is provided to the cylindrical member, each of the diameter decreasing members having (i) an inner diameter that decreases as the each of the diameter decreasing members extends downward and (ii) a gas inlet opening at a lower end of the each of the diameter decreasing members;
• spouted bed type olefin polymerization reaction regions each of which is surrounded by (a) an inner surface of a corresponding one of the diameter decreasing members and (b) part of an inner surface of the cylindrical member which part extends upward from the corresponding one of the diameter decreasing members, each of the spouted bed type olefin polymerization reaction regions being a region in which a spouted bed is formed, the number of the spouted bed type olefin polymerization reaction regions being 3 or more;
• and
• at least one fluidized bed type olefin polymerization reaction region which is provided at a stage subsequent to the spouted bed type olefin polymerization reaction regions,
• wherein the method comprising the steps of:
• (1) polymerizing an olefin in the spouted bed type olefin polymerization reaction regions so as to obtain a propylene homopolymer component (I-1), a propylene copolymer component (I-2), or both of the propylene homopolymer component (I-1) and the propylene copolymer component (I-2);
• and
• (2) polymerizing an olefin in the at least one fluidized bed type olefin polymerization reaction region in the presence of the propylene homopolymer component (I-1), the propylene copolymer component (I-2), or both of the propylene homopolymer component (I-1) and the propylene copolymer component (I-2), each obtained in the step (1), so as to obtain a heterophasic propylene polymer material,
• wherein the heterophasic propylene polymer material is:
• a propylene polymer material containing the propylene homopolymer component (I-1) and a propylene copolymer component (II);
• a propylene polymer material containing the propylene copolymer component (I-2) and the propylene copolymer component (II);
• or
• a propylene polymer material containing the propylene homopolymer component (I-1), the propylene copolymer component (I-2), and the propylene copolymer component (II),
• wherein:
• the propylene copolymer component (I-2) is a copolymer component containing a propylene-based monomer unit and a monomer unit which is based on at least one kind of olefin selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms;
• and
• assuming that a total weight of the propylene copolymer component (I-2) is 100% by weight, the propylene copolymer component (I-2) contains the monomer unit, which is based on the at least one kind of olefin selected from the group consisting of the ethylene and the α-olefins having 4 to 12 carbon atoms, in an amount of not less than 0.01% by weight and less than 15% by weight,
• wherein:
• the propylene copolymer component (II) is a copolymer component containing (i) a monomer unit which is based on at least one kind of olefin selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms and (ii) a propylene-based monomer unit;
• and
• assuming that a total weight of the propylene copolymer component (II) is 100% by weight, the propylene copolymer component (II) contains the monomer unit, which is based on the at least one kind of olefin selected from the group consisting of the ethylene and the α-olefins having 4 to 12 carbon atoms, in an amount of not less than 15% by weight and not more than 80% by weight,
• wherein, assuming that a total weight of the heterophasic propylene polymer material is 100% by weight, the heterophasic propylene polymer material contains the propylene copolymer component (II) in an amount of not less than 32% by weight.