COMPOSITION DE REVETEMENT DE BASE A L'EAU POUR VEHICULES AUTOMOBILES, SON PROCEDE D'APPLICATION ET ARTICLE REVETU AINSI OBTENU

A water-based coating composition for automobiles comprises a resin in emulsion obtained by emulsion polymerization of a mixture of alpha,beta-ethylenically unsaturated monomers with an acid index of 3-50 and comprising at least 65 wt.% of (meth)acrylate ester with 1 or two carbon atoms in the ester part, a coloring component comprising an optically coherent lamellar pigment and an acrylic polymer of specified formula and weight average mol.wt. 400,000-1,500,000 The acrylic polymer is of Formula (I): A-(CH(M)-CH2)m-(-CH(N)-CH(R)-)n-B (I) A, B = a terminal group formed by radical polymerization or a terminal group resulting from the hydrolysis of it, H, OH; M = carboxylic acid, carboxylic acid group neutralized with ammonia or a primary or secondary or tertiary amine; N = carboxylic acid, ester of carboxylic acid in which the ester part contains one or more carbon atoms, a carboxylic acid group neutralized with ammonia or a primary or secondary or tertiary amine; m = integer 1 or more; n = integer at least 0 on condition that m/9 is not less than n; R = H, methyl. The content of the polymer is 0.3-4.0 wt.% of solids with respect to the solids of the resin. The composition further comprises a polyether polyol having on average at least 0.02 primary hydroxyl groups per molecule, a number average mol.wt. 300- 3000 and a water tolerance of at least 2.0. Preferably it contains at least one hydroxyl group per molecule and has a hydroxyl index of 30-700. Independent claims are included for: (1) a method of forming a multilayer coating comprising applying the claimed composition to an article, applying over it a transparent coating composition and hardening by heating; and (2) an article comprising a film formed from the composition.