Patent GB-985144-A (GB)
Title: Process for purification of isocyanate group-containing compounds
Inventor: HALL JOHN ALWYN
IPC: C08G18/70
Filed: 1962-03-27
Abstract: Isocyanate group-containing reaction products of organic diisocyanates with organic compounds containing at least two alcoholic hydroxyl groups and isocyanurate polymers of organic diisocyanates contaminated with said diisocyanates are purified by heating said reaction product or polymer in a solvent inert towards the isocyanate group with a diisocyanate-absorptive material inert towards and insoluble in said solvent and selected from active carbon, alumina, silica gel, gelatine, glue, siliceous earths, natural and synthetic rubbers, polyamides, polyvinyl acetate, polymethyl methacrylate and polystryene and subsequently removing the absorbent.  The purification is conveniently performed at between 0 DEG  and 100 DEG  C. by agitating a solution containing 20-80% by weight of the reaction product or polymer with 1 to 40% by weight of the reaction product or polymer of absorbent which has previously been dried by heating in vacuum at 120 DEG  C. The treatment time is normally greater than 10 hours after which the absorbent is removed by, for example, filtration or centrifugal means.  The process of the invention is especially useful when applied to the reaction products or polymers of tolylene-2 : 4- or -2 : 6-diisocyanate, hexamethylene diisocyanate or mixtures thereof.  Specified inert solvents are ethyl, butyl and ethoxy ethyl acetates, methyl isobutyl ketone, acetone, toluene, xylene or mixtures thereof.  Specifications 795,051 and 795,052 are referred to.ALSO:Isocyanate group-containing reaction products of organic diisocyanates with organic compounds containing at least two alcoholic hydroxyl groups and isocyanurate polymers of organic diisocyanates contaminated with said diisocyanates are purified by heating said reaction product or polymer in a solvent inert towards isocyanate groups with a diisocyanate-absorptive material inert towards and insoluble in said solvent and selected from active carbon, alumina, silica gel, gelatine, glue, siliceous earths, natural and synthetic rubbers, polyamides, polyvinyl acetate, polymethyl methacrylate and polystyrene and subsequently removing the absorbent.  The purification is conveniently performed at between 0 DEG  and 100 DEG  C. by agitating a solution containing 20-80% by weight of the reaction product or polymer with 1 to 40% by weight of the reaction product or polymer of absorbent which has previously been dried by heating in a vacuum at 120 DEG  C.  The treatment time is normally greater than 10 hours after which the absorbent is removed by, for example, filtration or centrifugal means.  The process of the invention is especially useful when applied to reaction products or polymers of tolylene-2 : 4- and -2 : 6-diisocyanates, hexamethylene diisocyanate or mixtures thereof and in particular isocyanurate or mixed isocyanurate polymers of said diisocyanates and reaction products of said diisocyanates with trihydric alcohols.  Specified inert solvents are ethyl, butyl and ethoxy ethylacetates, methyl isobutyl ketone, acetone, toluene, xylene or mixtures thereof. Specifications 795,051 and 795,052 are referred to.