SEALANTS MADE USING LOW UNSATURATION POLYOXYALKYLENE POLYETHER POLYOLS

摘要

There is provided an sealant made with an isocyanate or hydroxyl terminated prepolymer made by reacting a stoichiometric excess of an organic polyisocyanate with polyols made of at least a polyoxyalkylene polyether triol or a mixture thereof with a polyoxyalkylene polyether diol. The triol or diol has a degree of unsaturation of 0.06 meq KOH/g of polyol or less and has within its structure the nucleus of an initiator compound, an internal block of oxypropylene groups, and a second block of oxyalkylene groups, wherein the internal block of oxypropylene is between said nucleus and said second block, said second block is made of oxyalkylene groups derived from a C4 or higher alkylene oxide. The amount of the internal block of oxyalkylene groups is from 25 weight percent to 80 weight percent based on the weight of all oxyalkylene groups and initiator in the polyether polymer, and the amount of the second block is effective to reduce the degree of unsaturation of said polyether to 0.06 meq KOH/g of polyol or less. The sealant has a CI of 25.degree.C or less, and may be a two component or a one component moisture cured sealant.