Coating composition comprising at least 3 components, process for its preparation, and its use

A process for coating plastics with a coating composition comprising the steps of:

• a) providing a three-component coating composition comprising
• (a) a first component comprising a solution or dispersion of at least one binder in one or more organic, water-dilutable solvents, wherein the binder is selected from the group consisting of:
• (A1) acrylate copolymers having a number-average molecular weight of from 1000 to 30,000, an OH number of from 40 to 200 mg of KOH/g, and an acid number of from 5 to 150 mg of KOH/g;
• (A2) polyester resins having a number-average molecular weight of from 1000 to 30,000, an OH number of from 30 to 250 mg of KOH/g, and an acid number of from 5 to 150 mg of KOH/g;
• (A3) polyurethane resins having a number-average molecular weight of from 1000 to 30,000, an OH number of from 20 to 200 mg of KOH/g, and an acid number of from 5 to 150 mg of KOH/g,
• and mixtures thereof, and a neutralizing agent,
• wherein a 50% solution of the binder portion of the first component in ethoxyethyl propionate has a viscosity at 23° C. of ≦2.5 dPa·s;
• (b) a second component comprising a crosslinking agent comprising
• (F1) at least 70% by weight of at least one member selected from the group consisting of nonblocked diisocyanates, nonblocked polyisocyanates, and mixtures thereof,
• (F2) from 2 to 20% by weight of at least one epoxide compound having at least 2 epoxide groups per molecule, and
• (F3) from 2 to 20% by weight of at least one amino resin, and
• (c) a third component that is essentially binder-free and contains water,
• b) mixing the first and second components of the composition,
• c) adding a coating additive to the mixed first and second components to provide a mixture,
• d) dispersing the mixture into the third component to provide a coating composition, and
• e) coating a plastic substrate with the coating composition by means selected from the group consisting of spraying, knife-coating, brushing, and dipping.