Low melting urethane linked toluenediisocyanates.

摘要

This invention relates to urethane linked mixtures of 2,4-and 2,6- toluenediisocyanates (ULTDI dimers) having low melting points and to a method of forming these systems. The urethane linked toluenediisocyanates containing from 45-90% of the 2,4-and 10-55% of the 2,6- isomer by weight are formed by reacting two moles of an appropriate isomer mix of toluenediisocyanate, with one mole of a specific alkylene glycol, e.g., 1,2-butanediol, diethylene glycol or dipropylene glycol under conditions such that essentially only one of the isocyanate groups on a toluenediisocyanate molecule reacts with a hydroxyl group of the glycol. Conditions are controlled such that the urethane linked toluenediisocyanates are formed. The resulting product, which has two unreacted isocyanate groups, is suited for producing a variety of elastomers including polyurethane polyurethane/urea or polyurea elastomers.