Process for the production of a multicoat coating, aqueous coating compositions, water-thinnable polyacrylate resins and process for the production of water-thinnable polyacrylate resins

摘要

PCT No. PCT/EP91/00480 Sec. 371 Date Nov. 24, 1992 Sec. 102(e) Date Nov. 24, 1992 PCT Filed Mar. 14, 1991 PCT Pub. No. WO91/14711 PCT Pub. Date Oct. 3, 1991.The invention relates to a process for the production of a multicoat coating in which an aqueous transparent topcoat composition containing a polyacrylate resin as binder is employed. The polyacrylate resin can be obtained by adding, either successively or alternately in part amounts, a mixture of a carboxyl-containing ethylenically unsaturated monomer (a1) and a monomer (a2) free from carboxyl groups and a mixture (b) consisting of (meth)acrylic acid esters which are free from carboxyl groups, of hydroxyl-containing ethylenically unsaturated monomers and, if appropriate, of other ethylenically unsaturated monomers to an organic solvent and carrying out a polymerization in the presence of a radical-forming initiator and, at the end of the polymerization, neutralizing the resultant polyacrylate resin and dispersing it in water. The type and amount of (a1), (a2) and (b) are chosen so that the polyacrylate resin has a hydroxyl value of 40 to 200, an acid value of 20 to 100 and a glass transition temperature (TG) of -40 DEG C. to +60 DEG C.