| abstract |
OLEFIN BLOCK COPOLYMERS ARE PREPARED BY A FLUIDIZED-BED POLYMERIZATION PROCESS WHEREIN A VAPOROUS FEED IS PASSED UPWARDLY THROUGH MULTIPLE REACTION ZONES IN INTIMATE CONTACT WITH DOWNWARDLY FLOWING FLUIDIZED CATALYST AND POLYMER PARTICLES, OLEFIN A BEING CONTINUOUSLY INTRODUCED INTO AN UPPER POLYMERIZATION ZONE, OLEFIN B BEING CONTINUOUSLY INTRODUCED INTO A LOWER POLYMERIZATION ZONE, AND A A-B BLOCK COPOLYMER PRODUCT BEING CONTINUOUSLY WITHDRAWN FROM THE LOWEST POLYMERIZATION ZONE. |