Aqueous coating compound, a process for its preparation and its use in processes for multilayered lacquering
First Claim
1. An aqueous coating composition, containing a binder which comprises(I) from 60% to 100% wt. of a mixture of(i) from 5% to 95% wt. solids basis based on(I) of an aqueous dispersion of one or more self-emulsifying polyurethane resins having a number average molecular weight of from 30,000 to 300,000 and containing carboxyl groups corresponding to an acid number of from 5 to 50, said resins having been obtained by chain lengthening in water a water-dispersible polyurethane prepolymer having more than one free isocyanate group per molecule, and(ii) from 95% to 5% wt. solids basis based on (I) of an aqueous dispersion of at least one acrylated polyester, or at least one acrylated polyurethane, or at least one acrylated polyester and at least one acrylated polyurethane, and(II) from 0 to 40% wt. of one or more formaldehyde condensation resin, one or more blocked polyisocyanate, or one or more formaldehyde condensation resin and one or more blocked polyisocyanate.
1 Assignment
0 Petitions
Accused Products
Abstract
Aqueous coating compound containing a polyurethane resin-based binder of
I) from 60 to 100% by weight of a mixture of
A) from 5-95% by weight of one or more self-emulsifying polyurethane resins in aqueous dispersion having a number average molar mass (Mn) of from 30000 to 300000 and containing carboxyl groups corresponding to an acid number of from 5 to 50, obtainable from a water dispersible polyurethane prepolymer having more than one free isocyanate group per molecule, by chain lengthening with water and
B) from 95 to 5% by weight of one or more acrylated polyesters and/or acrylated polyurethanes having an acid number of from 5 to 50 in aqueous dispersion and
II) from 0 to 40% by weight of one or more formaldehyde condensation resins and/or blocked polyisocyanates,
the percentages by weight being based in each case on the resin solids content. The coating compounds are suitable in particular as basic lacquers for multi-coat lacquering. Coatings with good weather resistance are produced from them.
-
Citations
9 Claims
-
1. An aqueous coating composition, containing a binder which comprises
(I) from 60% to 100% wt. of a mixture of (i) from 5% to 95% wt. solids basis based on(I) of an aqueous dispersion of one or more self-emulsifying polyurethane resins having a number average molecular weight of from 30,000 to 300,000 and containing carboxyl groups corresponding to an acid number of from 5 to 50, said resins having been obtained by chain lengthening in water a water-dispersible polyurethane prepolymer having more than one free isocyanate group per molecule, and (ii) from 95% to 5% wt. solids basis based on (I) of an aqueous dispersion of at least one acrylated polyester, or at least one acrylated polyurethane, or at least one acrylated polyester and at least one acrylated polyurethane, and (II) from 0 to 40% wt. of one or more formaldehyde condensation resin, one or more blocked polyisocyanate, or one or more formaldehyde condensation resin and one or more blocked polyisocyanate.
-
5. A process for the preparation of a binder for aqueous coating compounds by the reaction of
a) one or more polyisocyanates, b) one or more polyether diols and/or polyester diols, each having a number average molar mass of from 500 to 5000, up to 30% by weight of which may be replaced by one or more low molecular weight polyhydroxyl compounds having a molar mass of from 60 to 400, and c) one or more dimethylol alkane carboxylic acids in an NCO/OH equivalent ratio of from 1.0: - 1 to 2.0;
1, preferably from 1.1;
1 to 1.9;
1, followed by chain lengthening of the polyurethane prepolymer with water. - View Dependent Claims (6, 7)
- 1 to 2.0;
Specification