GB1218221A - Improvements in and relating to polymerization of olefines - Google Patents

Abstract

1,218,221. Polymer purification. EASTMAN KODAK CO. 6 May, 1968 [4 May, 1967; 18 Dec., 1967], No. 21303/68. Heading C3P. In the polymerization of olefines, catalyst residues are removed from the polymer solution by filtering to remove a major portion of catalyst residues, followed by contacting the filtered polymer solution with alumina. A filter aid having a micron retention rating of greater than three may be added to the polymer solution before filtering. The filtering may be performed at from 150‹ to 250‹ C. under conditions such that there is a pressure drop across the filter of below 50 p.s.i.g. The filtered solution may be contacted with alumina at a temperature of 150‹ to 250‹ C. and a pressure of 50 to 300 p.s.i.g. The filtered polymer solution, after contact with alumina, is preferably concentrated to between 70 and 80% by weight polymer, and the polymer concentrate thus formed may be extruded and extracted with a solvent capable of dissolving amorphous polymer. The polyolefine may be obtained from at least one alpha monoolefine having from 2 to 20 carbon atoms, or alternatively the polyolefine may be a polyallomer, i.e. a crystalline, block polymer synthesized from two or more olefins in which the individual segments exhibit degrees of crystallinity normally associated only with alphaolefin homopolymers. The catalyst may be an oxide of chromium molybdenum or vanadium, or lithium or compound thereof in combination with a transition metal halide. The polymerization may be carried out in an organic solvent at a temperature of 120‹ to 300‹ C. and pressure of up to 2000 atmospheres. In the examples, (1) propylene is polymerized in mineral spirits in the presence of a catalyst system comprising lithium aluminium hydride, titanium trichloride and optionally one or more of lithium, sodium fluoride and magnesium oxide, (2) a propyleneethylene polyallomer is prepared by polymerizing in two stages the monomers in the presence of lithium dialuminium heptahydride, titanium trichloride and sodium fluoride, in mineral spirits. The polymers obtained in (1) and (2) are each purified by filtration followed by contacting with alumina.