Liquid carbodiimide-uretonimine modified polymethylene polyphenylene polyisocyanates and polyurethane foams made therefrom

Abstract From the Canadian patent

A process for the preparation of liquid polymethylene polyphenylene polyisocyanate blends containing carbodiimide-uretonimine isocyanate linkages containing a, high two-ring methylene bis(phenylisocyanate) content and, light colored polyurethane foams made therefrom. The process is comprised of reacting polymethylene polyphenylene polyisocyanate with a catalytically effective amount of a carbodiimide-uretonimine promoting compound at a temperature sufficient to promote the formation of carbodiimideuretonimine linkages and an isocyanate content of about 25 percent and the desired viscosity is reached and then, reacting that product to deactivate the carbodiimideuretonimine catalyst, and …