Solvent-free polyurethane dispersion

A solvent-free polyurethane dispersion, wherein the polyurethane polymer has a mean molar mass (number average) of from 25,000 to 100,000 dalton and a solids content of polyurethane polymer of from 40 to 70% by weight, based on the total amount of a pure polyurethane dispersion, said dispersion obtained by

• a) allowing from 10 to 50% by weight of a relatively high molecular weight polyol component (A) (i) which has at least two hydroxyl groups which are reactive toward polyisocyanates and a molar mass of from 500 to 6000 dalton plus, if desired, from 0.5 to 5% by weight of a low molecular weight polyol component (A) (ii) having at least two hydroxyl groups which are reactive toward polyisocyanates and a molar mass of from 60 to 150 dalton to react with from 5 to 25% by weight of a polyisocyanate component (B) comprising at least one polyisocyanate, polyisocyanate derivative or polyisocyanate homologue containing at least two aliphatic and/or aromatic isocyanate groups in the presence or absence of a catalyst to give a polyurethane preadduct, then
• b) reacting the polyurethane preadduct from step a) with from 0.5 to 5% by weight of a low molecular polyol component (A) (iii) containing at least two hydroxyl groups which are reactive toward polyisocyanates and at least one carboxyl group which is inert toward polyisocyanates and can in the presence of bases be converted completely or partially into carboxylate groups to give the corresponding prepolymer, wherein the NCO/OH equivalent ratio of components (B) and (A) is approximately 1.5:1 to 2.5:1,
• c) allowing the prepolymer from step b) to react with from 0.25 to 2.5% of a neutralization component (C) until the carboxyl groups have been completely or partially neutralized, subsequently or simultaneously,
• d) dispersing the neutralized prepolymer from step c) in from 10 to 60% by weight of water which may contain from 10 to 70% by weight of a formulation component (F) selected from among fillers, pigments, plasticizers, fibrous materials and/or other customary additives, subsequently
• e) reacting the dispersion from step d) with from 0.25 to 2.5% by weight of a chain extension component (D) comprising at least one polyamine having at least two amino groups which are reactive toward polyisocyanates, and
• f) if desired, allowing the dispersion from step e) to react with from 0.05 to 0.5% by weight of a chain stopper component (E) selected from at least one monoamine having an amino group which is reactive toward polyisocyanates.