Multistage process for producing polypropylene compositions

摘要

A process for polymerizing propylene in the presence of a polymerization catalyst by copolymerizing propylene with a comonomer selected from the group of ethylene and C4-C10 alpha-olefins in three polymerization stages. The polymers produced in the three stages have different melt flow rates and comonomer contents. The polymer composition produced by the process has good mechanical properties and can be used for making pipes. The process has a good productivity.