REDUCING CATALYST PRECIPITATION DURING POLYMER ISOLATION

1328554 Isolation of polymers E I DU PONT DE NEMOURS & CO 11 Nov 1970 [17 Nov 1969] 53673/70 Heading C3P Elastomeric polymers, prepared in solution using a co-ordination catalyst having a transition metal component, are isolated by a process comprising (a) mixing the polymer solution with water or steam to deactivate the catalyst and form an aqueous phase, (b) adding 0À05 to 2 moles of a bisulphate, bisulphite or persulphate salt per mole of the transition metal catalyst component, (c) separating the aqueous phase from the polymer solution and (d) separating the polymer from the solvent. The polymer may be, e.g. a conjugated diene polymer or an olefin-non-conjugated diene copolymer. Usually steam is used in step (a) to vaporize unreacted monomers. The process is exemplified by the isolation of an ethylenepropylene-1,4-hexadiene copolymer prepared in tetrachloroethylene using a VOCl 3 -(i-Bu) 2 AlCl catalyst, the additive in step (b) being sodium bisulphate. Other additives mentioned are potassium bisulphate, ammonium and potassium persulphates, potassium metabisulphite and sodium bisulphite.