GB1116501A - Process for the purification of polyethers - Google Patents

Abstract

Polyethers, which are obtained by polymerizing a cyclic oxide in the presence of an acidic or basic catalyst, are purified by treating the polymerization product with a basic or acidic substance in an amount approximately stoichiometrically equivalent to the amount of catalyst present and thereafter filtering the substantially neutral polyether through a layer of synthetic magnesium silicate. The treatment of the polyether may be effected at normal or elevated temperatures and water in an amount of 2 to 30% by wt. of the polyether is preferably added before or after the addition of the basic or acidic substance. Specified basic materials are sodium carbonate, bicarbonate, and acetate, calcium hydroxide, calcium carbonate and barium hydroxide, and specified acidic materials are sulphuric, phosphoric, acetic acid, oxalic, glutaric and adipic acids. The synthetic magnesium silicate layer may be formed by slurrying the latter, preferably in admixture with an inert porous solid as filter aid, with a polyether similar to that to be purified and then passing the slurry through a filter to give a pre-coat layer; the layer preferably contains 0.1 to 1% by wt. of magnesium silicate based on the weight of polyether to be purified. The polyethers may be polymers or copolymers of cyclic oxides, e.g. ethylene oxide, epichlorhydrin, 1,2-propylene and -butylene oxides, 2, 3-butylene oxide, oxacyclobutane, substituted oxacyclobutanes and tetrahydrofuran, or the cyclic oxide may be polymerized in the presence of a compound containing one or more active hydrogen atoms, e.g. monohydric alcohols, monohydric phenols, monocarboxylic acids, H2O, NH3, hydrazine, glycols, glycerol, trimethylol propane, triethanolamine, pentaerythritol, sorbitol, sucrose, phloroglucinol, ethanolamine and ethylene and tolylene diamines, and such polyethers may have a molecular weight of 200-10,000. The polyether may also be stabilized with an antioxidant, e.g. a sterically hindered phenol, either before or after neutralization. The products may be employed in the production of polyurethanes.