GB590595A - Improved process and apparatus for the polymerisation of iso-olefins - Google Patents

Abstract

<PICT:0590595/IV/1> <PICT:0590595/IV/2> An iso-olefine having up to 8 carbon atoms with or without a minor proportion of a polyolefine having from 4 to 14 carbon atoms is continuously polymerized at a temperature below -60 DEG F. in the presence of a Friedel-Crafts catalyst, to form a slurry of cold polymer particles in cold reaction liquid, the slurry is withdrawn from the reaction zone and the polymer particles separated from the liquid at substantially the same temperature, the liquid being returned to the reaction zone and the solid particles led into warm water to flush off residual reaction liquid and form an aqueous slurry of polymer. The specified proportions of polymerizable materials comprise from 50-95 per cent of iso-olefine and from 50-5 per cent of a C4 diolefine, or (when used) less than 10 per cent of a C5 or higher diolefine. The preferred iso-olefine is isobutylene and listed polyolefines include butadiene, isoprene, piperylene, dimethyl butadiene, myrcene and dimethylallene. Preferably, the process p is carried out in solution, liquid ethylene and alkyl halides being specified solvents and the Friedal-Crafts catalyst is dissolved in a low-freezing inert solvent, e.g. alkyl halides, carbon disulphide or sulphuryl chloride. In Fig. 1, an internal refrigerant, e.g. liquid ethylene, is used in the continuous polymerization vessel 1 and the cold slurry of polymer is continuously withdrawn through line 9 and pumped to the sump 10 of an enclosed rotary filter 11 operated at the same temperature as the reaction vessel. As the filter drum is rotated a doctor blade 17 removes the polymer which drops on to a vibrating feeder 18 which conducts it into the flash chamber 19. Steam and water are sprayed on to the polymer on an endless screen as it moves past the jets 21. The copolymer is dried, e.g. in a hot air tunnel drier. In Fig. 2, cold slurry from the reaction vessel is pumped through line 61 to an enclosed jacketed or refrigerated chamber 62 provided with a vibrating screen 63. The slurry is distributed from weir box 64 across the screen, cold liquid passing through and is collected and discharged through line 66 back to the reaction system, and polymer particles falling through hopper 72 into heated liquid in the flash chamber 71. Specifications 432,196, 580,407, [Group III], and Australian Specification 112,875 are referred to.