Procédé de purification de polyoléfines à haut poids moléculaire

A process for the purification of high molecular weight polyolefines obtained by polymerization using a catalyst comprising an organometallic compound and a transition metal compound, characterized in that after decomposition of the catalyst complex with alcohols, impurities are removed from the polyolefine by washing with a mixture of an aqueous solution of a non-ionic surface-active agent and a complex-forming agent in the presence of non-polar or weakly polar solvents, whereafter the polyolefine is separated from the wash medium until the disappearance of the surface-active agent from the washing water, and then the polyvalent salt solution of the complex-forming agent is extracted from the polymer with a non-polar or weakly polar solvent. The complex forming agent may be selected from water-soluble salts of phosphoric acids including phosphates, pyrophosphates and polymeric phosphates and aminopolycarboxylic acids or salts thereof, for example the sodium salt of ethylene-diamine-tetra-acetic acid or nitrilotriacetic acid. In the example, polyethylene or polypropylene are treated with an alcohol and then purified by washing with a mixutre of water, the sodium salt of ethylene-diaminetetra-acetic acid and octylphenol condensed with ethylene oxide at a pH of 9 to 11, followed by washing out with soft water until the surfaceactive agent disappers from the washing water.