Polysulfide-based polyurethane sealant for insulating glass

摘要

An insulated glass sealant having the best characteristics of polysulfides and polyurethanes rather than the worst is made from a polysulfide-based polyurethane which, in turn, is derived from a mixture of hydroxyl terminated polysulfides having a structure represented by the following formula: wherein R = HO(CH2)ySS, y is from 2 to 6, and n is such that the molecular weight is from about 2500 to about 4000. The improved sealant of this invention is prepared by a one-step procedure wherein the hydroxyl terminated polysulfide of said formula is reacted with a polyisocyanate at a ratio between about 1:1 and about 1:1.2 on an equivalents basis. The hydroxyl-terminated polysulfide is made by splitting a polysulfide having a molecular weight about 30 times greater in an aqueous latex dispersion with a dithiodialkylene glycol and sodium sulfite.