Coating composition of an acrylic polymer, polyol and polyisocyanate crosslinking agent
AssigneeE. I. Du Pont de Nemours and Company
InventorsDouglas M. Lamb, John A. Simms
Life of this patent
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Abstract
A coating composition primarily used as a clear coat of a clearcoat/color coat automotive finish; the composition has a film forming binder solids content of about 30-70% by weight contains about (A) 50-80% by weight, based on the weight of the binder, of an acrylic polymer of polymerized monomers of styrene, and two methacrylate monomers and a hydroxy alkyl methacrylate or acrylate each having 1-4 carbon atoms in the alkyl group and the polymer has a number average molecular weight of about 1,000-12,000 and a calculated Tg of at least 40.degree. C. and (B) 1-20% by weight, based on the weight of the binder, of a polyol component and (C) 10-49% by weight, based on the weight of the binder, of an organic polyisocyanate.
Claims15
A clear coating composition which cures at ambient temperatures having a film forming binder solids content of about 30-70% by weight and an organic liquid carrier, wherein the binder contains about
- (A) 50-80% by weight, based on the weight of the binder, of an acrylic polymer consisting essentially of polymerized monomers of styrene, a methacrylate monomer selected from the group consisting of methyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate or any mixtures thereof, a second methacrylate monomer selected from the group consisting of n-butyl methacrylate, isobutyl methacrylate or ethyl hexyl methacrylate or any mixtures thereof and a hydroxy alkyl methacrylate or hydroxy alkyl acrylate each having 1-4 carbon atoms in the alkyl group;
- wherein the acrylic polymer has a number average molecular weight of about 1,000-12,000 determined by gel permeation chromatography and a calculated Tg of at least 40.degree. C.,
- (B) 1-20% by weight, based on the weight of the binder, of a polyol component comprising a compound of the formula of ##STR4## wherein:
- R.sup.1 is a covalent bond or alkylene containing 1, 2, 3 or 4 carbon atoms;
- n is about 1 to about 4;
- m is 2, 3 or 4;
- and
- Q is a saturated carbocyclic ring containing 5 or 6 carbon atoms, or S--R.sup.2 --T wherein S and T are each independently saturated carbocyclic rings containing 5 or 6 carbon atoms, and R.sup.2 is a covalent bond or an alkylene group containing 1, 2 or 3 carbon atoms;
- provided that no more than one R.sup.1 is bound to any c carbocyclic carbon atom, and further provided that when Q is S--R.sup.2 --T, each R.sup.1 is bound to a carbon atom of the carbocyclic rings of S and T and
- (C) 10-49% by weight, based on the weight of the binder, of an organic polyisocyanate.
Dependencies are inferred from the claim text.