Patent ID: 8349975
Filing Date: 2013-01-08
Classification: B01J,C08F

Abstract:
1. A method for transitioning from a first process for production of a first polymer to a second process for the production of a second polymer during a polymerisation campaign in a polymerisation apparatus, said polymerisation apparatus comprising a reaction vessel and a degassing vessel, in which the respective first and second processes each comprise: (a) bringing a principal olefin and a comonomer into contact with a catalyst under gas phase polymerisation conditions in the reaction vessel to form the respective first or second polymer, wherein said first and second process utilise the same principal olefin but differ in at least one of (i) the comonomer used and (ii) the reaction temperature at which the polymer is produced, and (b) subsequently contacting the respective first or second polymer with a purge gas in the degassing vessel to remove unreacted monomers, wherein the method for transitioning comprises changing the flow rate of purge gas in the degassing vessel from a first rate, X a. where T b. where T c. where T