Latex-reinforced polyurethane sewer sealing composition

Claim 1

A two-part curable composition suited when mixed for sealing water-bearing or water-holding structures, comprising: Part A: a fluid mixture comprising water-miscible organic solvent and water-soluble, non-crystallizing polyurethane prepolymer having terminal isocyanate groups formed by reacting (i) polyether polyol having at least two terminal hydroxyl groups and a number average molecular weight between about 3,000 and 20,000 and having random ethylene oxide units and higher alkylene oxide units in a mol ratio of ethylene oxide to higher alkylene oxide of 1:1 to 4:1, wherein said higher alkylene oxide is selected from a group consisting of propylene oxide, butylene oxide, pentylene oxide, hexylene oxide and mixtures thereof, and (ii) sufficient organic polyisocyanate compound having at least two terminal isocyanate groups to provide an NCO:OH ratio of about 5:1 to about 1.05:1; Part B: (1) sufficient aqueous polymeric latex selected from the group consisting of polyethylacrylate, polyurethane and acrylonitrile-butadiene-styrene copolymer, containing particulate polymeric material having an average particle size in the range of about 0.01 to about 10 microns to provide a weight ratio of prepolymer to polymeric material latex of about 100:1 to 1:1; and (2) sufficient water to provide a weight ratio of water to prepolymer on the order of 5:1 to 20:1 and to provide a viscous mass having a viscosity in the range of about 5 to about 1,000 cps when measured with a Brookfield RVT Viscometer at 25° C. using a standard No. 3 spindle rotated at 20 rpm.