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Process for the production of a two-coat finish on a substrate surface

  • US 5,716,678 A
  • Filed: 11/17/1995
  • Issued: 02/10/1998
  • Est. Priority Date: 03/31/1993
  • Status: Expired due to Term
First Claim
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1. A process for the production of a two-coat finish on a substrate surface, comprising the steps of:

  • (1) applying a pigmented basecoat to the substrate surface,(2) drying the basecoat film applied in step (1),(3) applying to the basecoat film dried in step (2) a nonaqueous, transparent topcoat comprising(A) a hydroxyl group-containing polyacrylate resin and(B) a crosslinking agent, wherein the crosslinking agent is a mixture of at least one amino resin and a member selected from the group consisting of blocked polyisocyanates, unblocked polyisocyanates, and mixtures thereof, and(4) baking and curing the basecoat and the topcoat together, wherein the hydroxyl group-containing polyacrylate resin of the nonaqueous, transparent topcoat is obtained by polymerizing(a) from 10 to 51% by weight of a compound selected from the group consisting of 4-hydroxy-n-butyl acrylate, 4-hydroxy-n-butyl methacrylate, and mixtures thereof,(b) from 0 to 36% by weight of a compound selected from the group consisting of hydroxyl group-containing esters of acrylic acid, hydroxyl group-containing esters of methacrylic acid, and mixtures thereof, wherein the compound is different from (a),(c) from 28 to 85% by weight of a compound selected from the group consisting of aliphatic esters of methacrylic acid, cycloaliphatic esters of methacrylic acid, and mixtures thereof, wherein the compound is different from (a) and (b) and has at least 4 carbon atoms in the alcohol radical,(d) from 0 to 3% by weight of a compound selected from the group consisting of ethylenically unsaturated carboxylic acids and mixtures thereof, and(e) from 0 to 20% by weight of a compound selected from the group consisting of ethylenically unsaturated monomers which are different from (a), (b), (c) and (d), and mixtures thereof,to give a polyacrylate resin having a hydroxyl number of from 60 to 200, an acid number of from 0 to 35, and a number-average molecular weight of from 1500 to 10,000, the sum of the proportions by weight of components (a), (b), (c), (d), and (e) always being 100% by weight, and the composition of component (c) being selected such that the polymethacrylate resin resulting from homopolymerization of component (c) has a glass transition temperature of from +10°

    to +100°

    C.

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