Production of polyurethane embedding materials

摘要

Production of a polyurethane embedding material from an aromatic diisocyanate in stoichiometric excess with a polyol mixture consisting essentially of castor oil and trimethylolpropane to first form a prepolymer containing unreacted isocyanate groups and being sufficiently flowable to permit coating onto membrane surfaces in all types of coating methods, and subsequently hardening the prepolymer by addition of a cross-linking agent consisting essentially of castor oil alone or another mixture of castor oil with trimethylolpropane in an amount sufficient to cross-link the prepolymer through at least a majority of its unreacted isocyanate groups. The products obtained in the invention are the embedding materials or the resulting hardened or cured embedded products or more simply "bedded" final products which have excellent properties particularly adapted to the mounting of semipermeable membranes in dialysis equipment to give an improved and more useful construction.