Polymer dispersion for coating, in particular on wood for blocking migrable compounds

摘要

The invention relates to an aqueous polymer dispersion, with said polymer comprising in its structure incorporated monomer units, from a monomer composition comprising: a) at least one (meth) acrylic ester (meth) acrylic monomer in C1- C18, without any ionic group, b) at least one ethylenically unsaturated monomer bearing at least one carboxylic acid group c) at least one (meth) acrylic monomer bearing a tertiary amine transformed by salification into a quaternary ammonium salt, and with said polymer additionally bearing grafted silane groups blocked in the form of -Si (OR1) 3 or –Si-R2 (OR1) 2 or -Si- (R2) 2 (OR1), preferably -Si (OR1) 3 or –Si-R2 (OR1) 2 with R1, R2, being an identical or different C1 to C4 alkyl, and with said blocked silane groups, resulting from at least one of the following two pathways or their combination: d) presence with the monomers a), b) and c) of at least one d) ethylenically unsat comonomer urea, carrying in addition to said ethylenic unsaturation, at least one blocked silane group as defined above and / or e) presence with the monomers a), b) and c) of, or post-treatment of the aqueous dispersion by at least one silane compound carrying a first blocked silane group as defined above and a second functional group selected from: epoxy, amino-, preferably epoxy, this second group being capable of reacting, at least in part with the carboxylic groups of said monomer b). The invention also relates to a coating composition comprising said dispersion of the invention and its use for aqueous compositions of protective coatings for wood.