Elastomeric coating compositions

Claim 1

A thermosetting, elastomeric coating composition sprayable at resin solids content of at least 40 percent by weight and being flexible such that when the coating composition is deposited on an elastomeric substrate and cured, the coated substrate can be bent around a 1/4-inch mandrel with the coating facing outwardly and the coating exhibits no breaks or cracks when tested at 70-75° F., comprising as the film-forming constituents: (A) a hard polyester polyol having at least 20 percent by weight cyclic moieties and the percentage of cyclic moieties being not greater than that required to achieve said flexibility, having a hydroxyl value of at least 80 and the hydroxyl value being not greater than that required to achieve said flexibility, a molecular weight of 300 or greater but not greater than that required for formulating said coating composition with a sprayability of at least 40 percent by weight, and said polyester polyol having a Sward Hardness value of at least 15, (B) a polyurethane polyol having a molecular weight of 2,000 or greater but not greater than that required for formulating said coating composition with a sprayability of at least 40 percent by weight, and said polyurethane polyol having a Sward Hardness value of less than 10, and (C) a curing agent capable of reacting with the active hydrogens in (A) and (B) to form a crosslinked coating selected from the class consisting of aminoplast and polyisocyanates; the difference in Sward Hardness values between (A) and (B) being greater than 10; the ratio of (A)+(B):(C) being within the range of 5 to 0.5:1; the weight ratio of (A)+(C):(B) being within the range of 100 to 1:1.