1results about How to "Increased melt flow rate" patented technology

This invention provides a method in which the polymerization activity in the first and second polymerization steps is excellent, easily producing propylene-based block copolymers with high melt flow rates and a high proportion of propylene / α-olefin copolymer components. A method for manufacturing a propylene-based block copolymer includes using an olefin polymerization catalyst, performing a first polymerization step, and then performing a second polymerization step. The olefin polymerization catalyst comprises (A) a solid catalyst component for olefin polymerization and (B) an organoaluminum compound. The (A) solid catalyst component for olefin polymerization contains titanium, magnesium, halogen, and a 1,3-diether compound. The first polymerization step is performed at a temperature of 45-65°C, where olefins containing 95-100% by mass of propylene are polymerized to obtain a propylene-based polymer. The second polymerization step is performed at a temperature of 50-90°C, in the presence of the propylene-based polymer, where olefins containing 5% by mass and less than 95% by mass of propylene and α-olefins other than propylene are copolymerized to obtain a propylene / α-olefin copolymer.