Abstract:
Heat-curable thixotropic mixtures containing carbamate and/or allophanate groups, comprising (A) at least one oligomer and/or polymer selected from the group consisting of oligomers and polymers containing allophanate groups, carbamate groups, and carbamate and allophanate groups, and (B) at least one thixotropic agent selected from the group consisting of urea or urea derivatives preparable by reacting at least one amine and/or water with at least one polyisocyanate, with the proviso that the mixture in question, based on its solids, further comprises at least one silica as thixotropic agent (C), and contains the thixotropic agent (B) in an amount of from 0.1 to 5% by weight if the oligomers and polymers (A) contain no allophanate groups; processes for preparing the mixtures, and their use as coating materials, adhesives and sealing compounds.
Abstract:
Clearcoat coating composition for automotive exterior coatings with improved intercoat adhesion to a subsequently applied coating layer and improved flexibility contains (a) a first vinyl copolymer prepared from a monomer mixture including no more than about 35% by weight of nonfunctional monomers that has carbamate functionality and hydroxyl functionality, at least part of the hydroxyl functionality being on monomer units including an optionally branched alkyl group having at least about six carbon atoms; (b) a second vinyl copolymer having hydroxyl functionality, preferably primary hydroxyl functionality; and (c) a curing agent component that includes at least an aminoplast curing agent and optionally a polyisocyanate curing agent. The polyisocyanate curing agent is preferably blocked with a blocking agent that volatilizes during the cure reaction, regenerating a reactive isocyanate group.