Chemistry and application of organic isocynates, VII. Conversion of hexamethylene diisocyanate into biuret and urea derivatives by means of hexamethylenediamine

Abstract Attempts of the conversion of hexamethylene diisocyanate (HDI) into biuret and urea derivatives by treatment with hexamethylene diamine (HDA) at 140°C, 155°C, and 170°C at different molar ratios of the reactants have been described. By means of gel permeation chromatographic analyses, the approximate contents of the mainly formed prepolymers were estimated. Also a scheme of the formation of all obtained oligomers has been proposed. On the basis of the results of physico‐chemical measurements, the influences of temperature and molar ratios of the reagents on the properties of the resulting products have been interpreted. It has been shown, that about 30 prepolymers of molecular weights (MW) up to 1300 having a biuret or a urea structure, are formed.