Ethylene Propylene Rubber Production

The process under analysis comprises three major sections: (1) Polymerization; (2) Purification; and (3) Finishing.

Polymerization. Initially, the monomers are treated and mixed is continuously supplied to a stirred, jacketed reactor, as well as a solution with the catalysts. The reaction occurs substantially in the liquid phase, with an excess of liquid propylene –used as diluent. The rate of polymerization is controlled by the rate of catalyst addition, while temperature control is readily accomplished by controlled evaporation of the propylene. As the polymer is formed, it precipitates out of the reaction medium.

Purification. The slurry is pumped into a vessel, where reaction is terminated and the slurry is mixed with small amounts of toluene and water. The toluene allows that the water extracts the catalyst entrained in the polymer. Subsequently, unreacted monomers and solvent are removed from the catalyst-free polymer slurry in steam strippers containing water as dispersing medium, and are recyled to polymerization reactor.

Finishing. The rubber polymer, present in the form of wet crumbs in water, is fed to a drum with auxiliary agents like anti-agglomerant , so as to ensure that copolymer particles stay suspended and show a reduced tendency to agglomerate. The crumb slurry, with moisture content as high as 90 wt%, is then pumped to a rotary screen where most of the free water is removed. The wet polymer is conveyed through a single screw extruder. While being conveyed through the extruder, water is expelled from the polymer. The extruded dried crumb, containing less than 0.5 wt% of water, is cooled down, baled and packed