Process for transitioning

摘要

Process for transitioning from the production of a first polymer to the production of a second polymer in a gas phase fluidized bed or stirred bed reactor by a) conducting a first polymerization reaction in the reactor using a first polymerization catalyst system to produce a first polymer, b) stopping the first polymerization reaction and removing at least the majority of the polymer in the reactor, c) introducing into the reactor a seed-bed containing at least 50 ppm of contaminants, in which the seedbed is maintained under at least 50 ppm but less than 500 ppm of contaminants during storage, and d) treating the seed-bed in the reactor to reduce the amount of contaminants. Step e) involves conducting a second polymerization reaction in the reactor to produce a second polymer.

主权项

1. A process for transitioning from the production of a first polymer to the production of a second polymer in a gas phase fluidised bed or stirred bed reactor, said process comprising the steps of:
a) Conducting a first polymerisation reaction in the reactor using a first polymerisation catalyst system to produce a first polymer, b) Stopping the first polymerisation reaction and removing at least the majority of the polymer in the reactor, c) Introducing into the reactor a seed-bed comprising at least 50 ppm of contaminants, wherein the seedbed has been maintained under at least 50 ppm but less than 500 ppm of contaminants during storage, d) Treating the seed-bed in the reactor to reduce the amount of contaminants, and e) Conducting a second polymerisation reaction in the reactor to produce a second polymer.