| abstract |
A fire-retardant protective coating is produced by dissolving a water-soluble polyisocyanate prepolymer in either an aqueous slurry or solution of fire-retardant materials and/or intumescent materials. After mixing, the gel produced can be applied as a coating which is useful for protecting or holding together surfaces vulnerable to fire, heat, air or minor abrasion. After the water evaporates, the cross-linked polyurethane coating has a large solids content of the fire-retardant and/or intumescent materials uniformly dispersed throughout. Preferred prepolymers are liquid with a molecular weight greater than about 2,000 and are made of a random copolymer of ethylene oxide and other alkylene oxides with isocyanate capping. |