Crosslinkable imide polyester coating
AssigneeValspar Sourcing, Inc.
InventorsGregory B. Hayes, Thomas J. Melnyk
Life of this patent
Estimating the term…
Abstract
A primer/topcoat coil coating system employs crosslinkable branched hydroxyl-functional polyester-imide resins derived or derivable from a symmetric aromatic imide trial and a diacid or acid-producing derivative. The primer resin has a hydroxyl number greater than about 90 but not more than about 215, the topcoat resin has a hydroxyl number greater than about 100 but not more than about 215, and the primer and topcoat can each be hardened in 30 seconds or less to provide a coating having at least 0T flexibility with no tape off and at least 2H pencil hardness.
Claims20
A coated substrate comprising a metallic substrate coil having first and second major surfaces and a primer and topcoat coating system on at least one major surface, wherein the primer and topcoat each comprise a binder containing (a) a branched hydroxyl-functional imide polyester resin derived or derivable from (i) a symmetric heterocyclic imide triol and (ii) a diacid or acid-producing derivative thereof, and (b) a blocked polyisocyanate crosslinking agent, wherein the primer imide polyester resin has a hydroxyl number greater than about 90 but not more than about 215, the topcoat imide polyester resin has a hydroxyl number greater than about 100 but not more than about 215, and the primer and topcoat can each be hardened in 30 seconds or less to provide a coating having at least 0T flexibility with no tape off and at least 2H pencil hardness.
A coated substrate according to claim 11 claim 1 wherein the primer imide polyester resin has a hydroxyl number of about 95 to about 120 and the topcoat imide polyester resin has a hydroxyl number of about 100 to about 125.
A method for making a coated coil, the method comprising the steps of:
- (a) providing a coil substrate;
- (b) providing primer and topcoat coating compositions each comprising (a) a branched hydroxyl-functional imide polyester resin derived or derivable from (i) a symmetric heterocyclic imide triol and (ii) a diacid or acid-producing derivative thereof, and (b) a blocked polyisocyanate crosslinking agent, wherein the primer imide polyester resin has a hydroxyl number greater than about 90 but not more than about 215 and the topcoat imide polyester resin has a hydroxyl number greater than about 100 but not more than about 215;
- (c) applying the primer coating composition onto at least one major surface of the substrate;
- (d) hardening the primer coating composition;
- (e) applying the topcoat coating composition onto the hardened primer composition;
- (f) hardening the topcoat coating composition;
- and
- (g) winding the thus-coated substrate into a coil.
A coil coating system comprising primer and topcoat coating compositions each comprising (a) a branched hydroxyl-functional imide polyester resin derived or derivable from (i) a symmetric heterocyclic imide triol and (ii) a diacid or acid-producing derivative thereof, and (b) a blocked polyisocyanate crosslinking agent, wherein the primer imide polyester resin has a hydroxyl number greater than about 90 but not more than about 215 and the topcoat imide polyester resin has a hydroxyl number greater than about 100 but not more than about 215.
Dependencies are inferred from the claim text.