Polyurethane coatings for bridge deckings and the like
AssigneeW. R. Grace & Co.-Conn.
InventorsCung Vu, Susan P. Buxbaum, Norman E. Blank, Richard C. Hartwig
Life of this patent
Estimating the term…
Abstract
Novel polyurethane formulations especially useful as membranes for the protection of bridge deckings. The polyurethane is prepared by mixing two components, A and B. Component A consists essentially of a low-molecular weight polyol, e.g., glycerol; a poly(oxypropylene) triol; and an elastomer. Component B is a special MDI, either a mix of 4,4'- and 2,4'-isomers of diphenylmethane diisocyanate or a mix of 4,4'-diphenylmethane diisocyanate and its reaction product with a low molecular weight poly(oxypropylene).
Claims16
Composition consisting essentially of two separate components, A and B:
- Component A consisting essentially of, in parts by weight, a low-molecular weight polyol having at least 3 hydroxyl groups and a molecular weight between 92 and about 200, about 3-10 parts;
- a poly(oxypropylene) triol containing only secondary hydroxyl groups, molecular weight about 500 to 3,000, 80-120 parts;
- and an elastomer, 0-60 parts;
- Component B, about 60-110 parts;
- being a polyisocyanate of the group consisting of (i) a mixture consisting essentially of a major portion of 4,4'-diphenylmethane diisocyanate and the balance 2,4'-diphenylmethane diisocyanate;
- or (ii)
- a polyisocyanate material comprising about 45-50 weight % 4,4'-diphenylmethane diisocyante and balance to make 100% of a polyisocyanate of the structure K--O--(CH.sub.2 CH[CH.sub.3 ]O).sub.m --K, where K is ##STR3## and m is about 2-5.
Dependencies are inferred from the claim text.