| 摘要 |
In a process for the purification of polyethylene, obtained by polymerization at pressures above 500 excess atmospheres, by freeing it from gaseous and volatile non-gaseous constituents including unreacted monomer, in which the polyethylene, after reaction using a catalyst in a reaction vessel, is led therefrom first into a separator which is at a lower pressure than the reaction pressure, preferably less than 5 excess atmospheres and thence in finely divided form with a large surface area into a degasification chamber in which the polyethylene is subjected to vacuum treatment and thence to an extruder, provision being made to exclude air over the whole path of the polyethylene from the reaction vessel to the extruder, steam is introduced into the separator at a temperature of about 150 DEG C. and is discharged from the separator together with a part of the gaseous and volatile constituents. Further steam, water or an organic solvent may be added to the polyethylene after it leaves the separator and before it enters the degasification chamber. Polymers miscible with polyethylene may be added thereto in the separator and further processed therewith. Apparatus suitable for carrying out the process of the invention is described and illustrated. |
