Process for producing ethylene-propylene block copolymer

• Main Authors: WAKAMATSU; KAZUKI, EBARA; TAKESHI, KAWAMATA; SHOUZOU, KOURA; HIROYUKI, SASAKI; YOSHIZUMI
• Format: Patent
• Language: English
• Published: 12.09.1995
• Edition: 6
• Subjects: CHEMISTRY; COMPOSITIONS BASED THEREON; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

The present invention relates to a process for producing ethylene propylene block copolymers excellent in appearance, elongation and impact resistance when molded by a gas phase polymerization which can be conducted in a stable manner. The process of the present invention comprises the first step of polymerizing propylene by using a catalyst system composed essentially of (A) a solid catalyst component containing magnesium, titanium, and a halogen as the indispensable ingredients, (B) an organoaluminum compound, and (C) a silicon compound represented by the formula R1R2Si(OR3)2, wherein R1 is an alicyclic hydrocarbon group and R2 and R3 are each a hydrocarbon group, to form a propylene homopolymer, and the second step of then polymerizing ethylene and propylene with further addition of a silicon compound represented by the formula R4R5aSi(OR6)3-a, wherein R4 is an aromatic hydrocarbon group, R5 is a hydrocarbon group or an aromatic hydrocarbon group, and a is a number satisfying the equation 0</=a<3, to form an ethylene-propylene copolymer.