| 摘要 |
A description is given of a solvent-free polyurethane dispersion having a high solids content of polyurethane polymer or fillers, which is obtainable bya) allowing a relatively high molecular weight polyol component (A) (i) and, if desired, a low molecular weight polyol component (A) (ii) to react with a polyisocyanate component (B) in the presence or absence of a catalyst to give a polyurethane preadduct, thenb) reacting the polyurethane preadduct from step a) with a low molecular weight and anionically modifiable polyol component (A) (iii) containing two or more hydroxyl groups and one or more carboxyl groups to give the corresponding prepolymer,c) allowing the prepolymer from step b) to react with a neutralization component (C) until the carboxyl groups have been completely or partially neutralized, subsequently or simultaneouslyd) dispersing the neutralized prepolymer from step c) in water which may further comprise a formulation component (F) comprising fillers, pigments, plasticizers, fibrous materials and other customary additives, subsequentlye) reacting the dispersion from step d) with a chain extension component (D), andf) if desired, allowing the dispersion from step e) to react with a chain stopper component (E).The polyurethane dispersion of the invention has an ideal linear segmented structure due to its method of preparation and has extraordinarily high solids contents combined with comparatively low viscosities, complete freedom from solvents, excellent materials properties (e.g. elasticity, elongation and tensile strength) and is prepared by a technically simple process.
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