A method of treating toluene diisocyanate distillation residues comprising reacting the residues with at least about 0.5 equivalents, based on hydrolyzable chloride concentration of the residues, of an epoxy compound at a temperature of from about 155 to about 220.degree. C. to produce a treated distillation residue having a hydrolyzable chloride level of less than about 800 parts per million (ppm) is taught. The product of the method is useful, for instance, in producing rigid foams with low K Factors.