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Method for improving the adhesion of the intermediate layer in a multi-paint finish

  • US 7,579,048 B2
  • Filed: 03/03/2004
  • Issued: 08/25/2009
  • Est. Priority Date: 03/15/2003
  • Status: Expired due to Fees
First Claim
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1. A process for improving the intercoat adhesion in a multicoat paint system produced by means of an integrated wet-on-wet process comprising(I) applying at least one primer material to the surface of a substrate, to form at least one primer film, and if desired drying the resulting primer film(s) 1, without fully curing it (them), or curing the primer film(s) 1 to give at least one primer coat 1,(II) applying at least one aqueous basecoat material 2 to the outer surface of the primer film(s) 1 or primer coat(s) 1 and if desired drying the resulting aqueous basecoat film(s) 2 without fully curing it (them),(III) applying at least one aqueous basecoat material 3 to the outer surface of the dried aqueous basecoat film(s) 2 and if desired drying the resulting aqueous basecoat film(s) 3 without fully curing it (them),(IV) applying at least one pseudoplastic powder clearcoat slurry 4 prepared by means of at least one of(α

  • ) a secondary dispersion process of emulsifying an organic solution comprising binder and crossliniker to give an emulsion of the oil-in-water type, removing the organic solvent or solvents, and replacing some or all of the subtracted solvent volume by water, to give the powder clearcoat slurry comprising spherical dimensionally stable particles, or(β

    ) a melt emulsification process in which at least one constituent of the powder clearcoat slurry is emulsified in the melt state, in an aqueous medium to form an aqueous emulsion of liquid particles and the emulsion is cooled to form an aqueous suspension of dimensionally stable particles, 

    to the outer surface of the dried aqueous basecoat film(s) 3 and optionally drying the resulting clearcoat film(s) 4, and(V) jointly curing the clearcoat film(s) 4, the aqueous basecoat film(s) 3, and the aqueous basecoat film(s) 2 and also where appropriate the primer film(s), if uncured, 1 to give the multicoat paint system comprising at least one primer coat 1, at least one aqueous basecoat 2, at least one aqueous basecoat 3, and at least one clearcoat 4;

    wherein the aqueous basecoat material(s) 2 employed in stage (II) comprise(s) as binder at least one dispersed graft copolymer (A/B) whose particles are composed of a hydrophobic core (A) of at least one copolymerized olefinically unsaturated monomer (a) and a hydrophilic shell (B) which comprises at least one polyurethane (b) and is prepared by subjecting the monomers (a) to free-radical (co)polymerization in the presence of at least one polyurethane (b) containing at least one olefinically unsaturated group selected from the group consisting oflateral and terminal ethenylarylene groups;

    lateral olefinically unsaturated groups attached to cycloaliphatic groups which constitute members of the main polymer chains;

    lateral cycloolefinically unsaturated groups which constitute members of the main polymer chains;

    terminal olefinically unsaturated groups attached to cycloaliphatic groups which constitute the end groups of the main polymer chains;

    terminal cycloolefinically unsaturated groups which constitute the end groups of the main polymer chains; and

    lateral and terminal olefinically unsaturated groups obtained by reacting polyurethanes with anhydrides of alpha,beta-unsaturated carboxylic acids and further wherein the aqueous basecoat material(s) 3 are different from the aqueous basecoat material(s) 2 and do not comprise the at least one dispersed graft copolymer (A/B) binder of the aqueous basecoat material(s) 2.

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