Method for producing self- emulsifiable aqueous polyurethane resins having improved characteristics

A method for producing self-emulsifiable, aqueous polyurethane resins comprising the steps of

• a) preparing a premix of polyol component (A), comprising 5 to 25 parts by weight of at least one diol (A) (i) having a molar mass of 500 to 5000 Dalton, 0.5 to 5 parts by weight of at least one polyhydroxyalkane;
• (A) (ii) 0 to 5 parts by weight of at least one anionically modifiable dihydroxyalkanecarboxylic acid (A) (iii);
• and 0 to 9 parts by weight of a solvent component (B);
• b) reacting 5 to 50 parts by weight of a polyisocyanate component (C) with 11 to 39 parts by weight of the premix from stage a) to give a polyurethane preadduct, the NCO/OH equivalent ratio in this stage being 1.75 to 8.0;
• c) reacting the polyurethane preadduct from stage b) with either 5 to 33 parts by weight of the premix from stage a) or 0.5 to 5 parts by weight of an anionically modifiable dihydroxyalkanecarboxylic acid (A) (iii) to give a polyurethane prepolymer, the NCO/OH equivalent ratio in this stage being 1.5 to 8.0, in particular 1.5 to 5.0;
• d) mixing the polyurethane prepolymer from stage c) with a prepared mixture of 0.5 to 4 parts by weight of a neutralizing component (D), and 0 to 1 part by weight of an antifoam component (E), and 5 to 225 parts by weight water taking proportions of this quantity of water to dilute a chain-extending component (F) in the ratio 1:10 to 10:1 by weight, and thereafter or simultaneously,
• e) reacting the aqueous polyurethane prepolymer from stage d) with 0.025 to 4 parts by weight of the chain-extending component (F), which has been diluted with water in stage d).