Patent ID: 7960468
Filing Date: 2011-06-14
Classification: C08G,C09D

Abstract:
1. An aqueous coating composition, consisting of: A) at least one water-dilutable hydroxy-functional binder, B) at least one polyisocyanate crosslinking agent with free isocyanate groups, C) 40% to 70% by weight of water based on the entire weight of said aqueous coating composition, and D) light stabilizers, flow control agents, rheology influencing agents, thickeners, anti-foaming agents, wetting agents, organic metallic salts, pigments, organic solvents, fillers or a combination thereof and wherein component A) consists of A1) 40-95 wt. % of at least one water-dilutable hydroxy-functional (meth)acrylic copolymer with a hydroxyl value of 60-250 mg of KOH/g and an acid value of 5-50 mg of KOH/g, which is obtained by free-radical copolymerization performed in a non-aqueous phase by I) polymerizing the following monomers in a first stage: a) 20-65 wt. % of a reaction product of a glycidyl ester derived from aliphatic saturated monocarboxylic acid with a tertiary or quaternary carbon atom in the alpha position and an unsaturated acid-functional monomer, b) 5-20 wt. % of at least one hydroxy-functional unsaturated monomer which differs from component a), c) 0-15 wt. % of an unsaturated acid-functional monomer and d) 5-70 wt. % of at least one other polymerizable unsaturated monomer, wherein the weight percentages of components a) to d) add up to 100 wt. % and II) polymerizing the following monomers in at least one further stage: b) 15-40 wt. % of at least one hydroxy-functional unsaturated monomer which differs from component a), c) 5-30 wt. % of an unsaturated acid-functional monomer and d) 30-80 wt. % of other polymerizable unsaturated monomers, wherein the weight percentages of components b) to d) add up to 100 wt. % and wherein the ratio of primary hydroxyl groups to secondary hydroxyl groups in the (meth)acrylate A1) copolymer is 1:0.1 to 1:1.2 and at least 80% of the secondary hydroxyl groups result from the monomers a), and A2) 5-60 wt. % of at least one water-dilutable polyester oligomer, wherein the total of the weight percentages of component A1) and A2) add up to 100 wt. % and wherein the free-radical polymerization for the production of component A1) is performed at least in part in the presence of component A2) and wherein said water-dilutable hydroxy-functional binder is converted into an aqueous form by partially or completely neutralizing acid groups with bases.