Aqueous coating composition based on low-solvent modified epoxy resin dispersions

A process for preparing an aqueous, low-solvent coating composition, which comprises

• (I) a modified epoxy resin dispersion comprising
• (A) an epoxy resin which is a condensation product of mass fractions of the following starting materials:
• (A-1) from 50 to 95% of one or more epoxide compounds having at least two epoxide groups per molecule
• (A-2) from 5 to 50% of an aromatic polyol;
• (B) a dispersant comprising
• (B-1) a condensation product of
• (B-11) an aliphatic polyol having a weight-average molar mass M.sub.W of from 200 to 20,000 g/mol, and
• (B-12) an epoxide compound having at least two epoxide groups per molecule;
• (C) a diluent comprising
• (C-1) ethylenically unsaturated, otherwise inert or, functional monomers capable of free-radical polymerization or copolymerization,
• (D) and water, and
• (II) an aqueous curing agent for the modified epoxy resin (I), which is suitable for curing at room temperature or at elevated temperatures which curing agent is selected from the group consisting of polyamines, Mannich bases, epoxy-amine adducts with free amino groups, polyamidoamines, and latent curing agents,
• wherein said process comprising the following steps:
• first preparing the epoxy resin (A) by condensation of components (A-1) and (A-2) at an elevated temperature in the presence of a condensation catalyst, then adding at least a portion of the diluent (C) at a lower temperature and, optionally, carrying out a partial reaction of the monomers (C-1) with the epoxy resin (A), subsequently incorporating the dispersant (B) by homogenization and obtaining an aqueous dispersion by portionwise addition of water (D), after which the monomers (C-1) are polymerized with the aid of an initiator system and, optionally, with the addition of the remaining diluent (C), and adding the aqueous curing agent (II) before the modified epoxy resin dispersion (I) is used.