Cationic water-dilutable binders

A process to coat substrates of base metals comprising dipping the substrates in a bath comprising a cationic water-dilutable binder, by cathodic electrodeposition followed by removing the substrate from the bath, rinsing or otherwise cleaning its surface, and subjecting the coated substrate to a drying step at a temperature of from 60° C. to 120° C. for a time between five minutes and two hours, and wherein optionally the dried coated substrate is further overcoated with at least one other layer,

• wherein the said cationic water-dilutable binder comprises a water-soluble bismuth salt or chelate complex B comprising bismuth ions and an organic acid-functional moiety, and a chain-extended epoxy-amine adduct EA which comprises moieties derived from
• epoxide compounds E2 having at least two epoxide groups per molecule,
• low molar mass epoxide compounds E3 having two epoxide groups per molecule, and a molar mass of from 170 g/mol to 800 g/mol,
• one or more of
• amidoamines A41 having at least one amide group and at least one amino group, made from amines A1 having at least two amino groups per molecule, and from three to twenty carbon atoms, selected from the group consisting of at least two primary amino groups per molecule, at least one primary and at least one secondary amino group per molecule, and at least two secondary amino groups per molecule, and a fatty acid A4 which has from six to thirty carbon atoms,
• further amines A1 having at least two amino groups per molecule, and from three to twenty carbon atoms, selected from the group consisting of at least two primary amino groups per molecule, at least one primary and at least one secondary amino group per molecule, and at least two secondary amino groups per molecule,
• an amine A2 which has from three to twenty carbon atoms and at least one secondary amino group per molecule,
• an amine A3 having from four to twenty carbon atoms and at least one tertiary, and at least one primary amino group per molecule,
• fatty acids A4 having from six to thirty carbon atoms, and one carboxylic acid group,
• phenolic compounds A5 having from six to twenty carbon atoms and at least two phenolic hydroxyl groups,
• diols A6 having from 4 to 8 carbon atoms,
• polyalkylene glycols A7, and
• optionally:
• epoxide compounds E1 having on average at least one, and less than two, epoxide groups per molecule wherein the cationic water-dilutable binder is free of an isocyanate crosslinker or blocked isocyanate crosslinker;
• and
• wherein the bismuth salt or chelate complex B comprising bismuth ions is present in an amount such that an amount of substance n(Bi) of elemental Bismuth, divided by a mass m(R) of resin solids present in a water dispersion formed with the chain-extended epoxy-amine adduct EA and bismuth salt or bismuth chelate complex is from 2 mmol/kg to 1000 mmol/kg.