The present invention generally relates to the field of cross-linkable aqueous vinyl polymer dispersions, to a coating composition comprising said cross-linkable aqueous vinyl polymer dispersions; to a paint formulation comprising said cross-linkable aqueous vinyl polymer dispersions; and to an article coated with the coating composition or the paint formulation.
In particular, the present invention provides an aqueous vinyl polymer dispersion PD which comprises the following polymers:
- 1) an aqueous dispersion of a vinyl polymer P1 obtainable by free radical emulsion polymerization of a monomers mixture comprising:
a) 5 to 20 wt% acid functional ethylenically unsaturated monomers M1 or precursors thereof;
b) 5 to 25 wt% ethylenically unsaturated monomers M2 containing a polyethylene glycol or monoalkoxy polyethylene glycol moiety;
c) up to 90 wt% of non-ionic ethylenically unsaturated monomers M3 other than M1 or M2;
d) 0 to 10 wt% ethylenically unsaturated monomers M4 with a functional group for cross-linking after film-formation;
e) 0 to 10 wt% of at least one chain transfer agent CTA;
where the sum of the wt.% of M1+M2+M3+M4+CTA = 100 wt%;

- 2) an aqueous dispersion or solution of a vinyl polymer P2 obtainable by free radical copolymerization of:
a) from 25 to 95 wt% of a ethylenically unsaturated monomers M5 selected from the group of N-vinyl amides with general structure:

where R 1 and R 2 are alkyl from C 1 to C 5 and may be connected to form a ring-structure, preferably N-vinyl pyrrolidone or N-vinyl caprolactam;
b) from 5 to 75 wt% of non-ionic ethylenically unsaturated monomers M3' other than M5
c) from 0 to 5 wt% of ethylenically unsaturated monomers M4' with a functional group for cross-linking after film-formation
d) from 0 to 10 wt% acid functional ethylenically unsaturated monomers M1' or precursors thereof;
e) from 0 to 5 wt% of at least one chain transfer agent CTA';
where the sum of the wt.% of: M5+M3'+M4'+M1'+CTA' = 100 wt%;

- 3) a film-forming vinyl polymer P3 under the form of an aqueous dispersion comprising:
i) from 20 to 60 wt% of a water-soluble or water dispersible crosslinkable vinyl oligomer OL obtained by emulsion polymerizing a monomer mixture comprising :
1) at least one acid functional ethylenically unsaturated monomer M1";
2) at least one ethylenically unsaturated monomer M4" with functionality for crosslinking upon film-formation, other than M1";
3) at least one ethylenically unsaturated monomer M3" other than M1" and M2", and
5) optionally, at least one chain transfer agent CTA", and

ii) from 40 to 80 wt% of a high molecular weight vinyl polymer P4 prepared by emulsion polymerizing, in the presence of the water-soluble or water-dispersible crosslinkable vinyl oligomer OL, a monomer mixture comprising:
1) optionally one acid functional ethylenically unsaturated monomer M1'";
2) optionally one or more ethylenically unsaturated monomers M4'" with functionality for crosslinking upon film-formation, other than M1'";
3) at least one ethylenically unsaturated monomer M3'" other than M1'" and M2'" and
4) optionally, one or more multifunctional ethylenically unsaturated monomers for pre-crosslinking, M5"', preferably in an amount less than 5 wt%,
- Where the total weight of film-forming vinyl polymer P3 = wt.% of the water-soluble or water dispersible crosslinkable vinyl oligomer OL + wt.% of the high molecular weight vinyl polymer P4= i) + ii) = 100 wt% and
- Where the total weight of the vinyl polymer in the aqueous vinyl polymer dispersion PD = wt.% of the vinyl polymer P1 + wt.% of the vinyl polymer P2 + wt.% of the film-forming vinyl polymer P3 = 100 wt%.