Aqueous Coating Composition
An aqueous coating composition contains a binder combination A) including A1) and A2) wherein A1) contains 60 to 90 wt % of a water-dilutable (meth)acrylate copolymer containing a) 10 to 80 wt % of a reaction product of a monoepoxyester and an unsaturated acid functional monomer, b) 0 to 40 wt % of a hydroxyl functional unsaturated monomer that is different from component a), c) 1 to 8 wt % of an unsaturated acid functional monomer, and d) 0 to 70 wt % of another polymerisable unsaturated monomer, and A2) contains 10 to 40 wt % of a water-dilutable epoxyester resin, and the aqueous coating composition further contains B) an isocyanate compound as a cross-linking agent.
1 - 7 . (canceled)
8 . A process for preparation of an aqueous coating composition comprising the steps
1) preparing a binder combination A) comprising
A1) 60 to 90 wt % of at least one water-dilutable (meth)acrylate copolymer comprising
a) 10 to 80 wt % of at least one reaction product of a monoepoxyester and an unsaturated acid functional monomer,
b) 0 to 40 wt % of at least one hydroxyl functional unsaturated monomer which is different from component a),
c) 1 to 8 wt % of at least one unsaturated acid functional monomer, and
d) 0 to 70 wt % of at least one other polymerisable unsaturated monomer, wherein the sum of the wt % of components a) to d) addg up to 100% by weight of A1), and
A2) 10 to 40 wt % of at least one water-dilutable epoxyester resin, wherein the binder combination is prepared by mixing together both the at least one binder A1) and A2) after their preparation and joint neutralizing this mixture by adding the appropriate amount of a base and conversion into an aqueous dispersion, wherein the sum of the wt % of components A1) and A2) add up to 100% by weight of A), and
2) adding at least one isocyanate compound as cross-linking agent B), wherein the sum of the wt % of components A) and B) add up to 100% by weight.
9 . The process according to claim 8 wherein the at least one water-dilutable (meth)acrylate copolymer comprises
a) 20 to 60 wt % of at least one reaction product of a monoepoxyester and an unsaturated acid functional monomer,
b) 10 to 30 wt % of at least one hydroxyl functional unsaturated monomer which is different from component a),
c) 2 to 6 wt % of at least one unsaturated acid functional monomer, and
d) 20 to 50 wt % of at least one other polymerisable unsaturated monomer, wherein the sum of the wt % of a), b), c) and d) add up to 100% by weight.
10 . The process according to claim 8 wherein the aqueous coating composition comprising A) 30 to 95 wt % solids of the binder combination and B) 5 to 70 wt % solids of the least one isocyanate compound as cross-linking agent, the sum of the wt % of components A) and B) add up to 100% by weight.
11 . The process according to claim 8 wherein the water-dilutable (meth)acrylate copolymer A1) has a hydroxy value of 30 to 250, an acid value of 15 to 50, and a number average molar mass (Mn) of 1000 to 15000.
12 . The process according to claim 8 wherein the water-dilutable epoxyester resin A2) has a hydroxy value of 30 to 400, an acid value of 10 to 50, and a number average molar mass (Mn) of 900 to 15000.