Use of polyisocyanate composition to make thermally crosslinkable coating paints or varnishes for car bodywork parts, having polyisocyanate, polymer compound e.g. acrylic polymer and aminoplastic resin e.g. urea-formaldehyde

摘要

Use of a polyisocyanate composition to prepare thermally crosslinkable coating. The composition comprises: a polyisocyanate having at least a dimer unit or an iminotrimer unit; a polymer compound having functional group with labile hydrogen e.g. primary or secondary hydroxyl-, phenol-, primary and/or secondary amine-, carboxylic or thiol group; and an aminoplastic resin like melaminealdehyde, preferably melamine-formaldehyde and/or urea-aldehyde e.g. urea-formaldehyde, or benzoguanamine and/or its alkoxyalkyl derivatives. Independent claims are included for: (1) a composition comprising a polyisocyanate having at least a dimer unit or an iminotrimer unit; a compound having functional group with labile hydrogen e.g. primary or secondary hydroxyl-, phenol-, primary and/or secondary amine-, carboxylic or thiol group; and an aminoplastic resin like melaminealdehyde, preferably melamine-formaldehyde and/or urea-aldehyde e.g. urea-formaldehyde, or benzoguanamine and/or its alkoxyalkyl derivatives, in which the molar ratio of isocyanate group to the iminotrimer group is less than 100, preferably less than 90, and/or the molar ratio of iminotrimer groups to the trimer is greater than 3; (2) a process of preparing the composition comprising mixing of the components of the composition just before the application of the coating or providing the composition in the form of a ready-mix formulation (monocomponent or 1K formulation), or in the form of a pre-mixture; (3) a coating comprising layers, preferably the first layer is obtained from the composition; and (4) a coated substrate obtained from the composition.