Prepn. of di:functional prepolymers contg. two isocyanate end gps. - by reacting di:isocyanate and di:thiol to form prepolymer

摘要

Diisocyanate is reacted with dithiol in a molar ratio of 10.0:1.0-10.0:9.0, pref. 10.0:5.0-10.0:9.0 to form a prepolymer of formula (A). In (A) X = average number; R, R' = (substd.) aliphatic, aromatic, araliphatic, cycloaliphatic, or other difunctional gp. e.g. ether or ester; and the two isocyanate gps. or two thiol gps. can be bound together. Pref. process is in the presence of solvents or diluents and/or catalysts e.g. tert. amines or metal complexes, pref. a medium without solvent or diluent. USE/ADVANTAGE - Prepolymers can be used to prepare composites, laminates, photoresists, adhesives, light-hardened printing or painting inks, networks, linear polymers, casting resins, overlays, and varnishes. Prepolymers have improved solubility, low soln. viscosity, low melt- and flow-range and existing reactive end gps. in utilisable concn. In an example, 8.412 go 2,2,4(2,4,4)-trimethyl hexamethylene diisocyanate were mixed with 3.646 g triglycoldithiol and 0.012 g pyridine. After 48 hours reaction at room temp., a colour free, viscous prepolymer of Mn 758 was obtd. (4pp Dwg.No.0/0)