Emulsifier-free coating agent, manufacture and use thereof

An emulsifier-free thermosettable coating agent in the form of an aqueous emulsion in which the resin component consists of:

• A) 30 to 70 wt. % of a polyester oligomer polyacrylate dilutable with water after neutralisation with bases and obtainable by radical polymerisation of
• 50 to 95 wt. % of one or more esters of unsaturated carboxylic acids with hydrophobic and hydrophilic components, in which
• a) the hydrophobic components are based on monomeric esters of unsaturated carboxylic acids with secondary OH groups, which can be present in a mixture with comonomers free from OH groups, and
• b) the hydrophilic components are based on monomeric esters of unsaturated carboxylic acids with primary OH groups and unsaturated monomers with COOH groups, which can be present in a mixture with comonomers free from OH groups, and
• the numerical ratio of primary to secondary OH groups originating from components b) and a) in the copolymer is 1 :
• 1.5 to 1 :
• 2.5, in
• 5 to 50 wt. % of one or more hydroxyfunctional polyester oligomers obtainable by polycondensation of one or more diols and/or polyols and one or more dicarboxylic acids and/or semiesters of dicarboxylic acids, optionally with use of one or more monoalcohols and/or one or more monocarboxylic acids, with a calculated molecular weight of 200 to 1000, a hydroxyl number of 100 to 600 and an acid number of 0 to 15,
• the monomers a) and b) being added in quantities such that the polyester oligomer polyacrylate has a hydroxyl number of 100 to 390, an acid number of 16 to 50 and a number average molecular weight (Mn) of 1000 to 10 000, and
• the percentages by weight in each case relating to the content of solids and adding up to 100 wt. %;
• and
• B) 70 to 30 wt. % of one or more polyisocyanates with free NCO groups,
• the percentages by weight of components A) and B) in each case relating to the solids content of the resins and adding up to 100 wt. %, and the ratio of OH groups in component A) to free NCO groups in component B) being between 0.5 :
• 1 and 2 :
• 1, and
• additionally containing water and optionally one or more organic solvents, pigments, fillers and/or conventional lacquer auxiliary substances and additives.