Polyurethanharz, Verfahren zu seiner Herstellung und seine Verwendung in wäßrigen Zweikomponenten-Klarlacken

摘要

The invention relates to a polyurethane resin which can be obtained in the following steps: (A) in a first reaction step (A), (a) one or several diisocyanates and/or polyisocyanates, (b) one or several compounds (b), having at least one group guaranteeing water dispersibility and more than one group which is reactive in relation isocyanates groups, and (c) optionally one or several compounds with at least two or a maximum of 3 OH groups reacted to form an intermediate product (A) with free isocyanate groups and urethane groups, (B) in a second reaction step (B), the intermediate product (A) obtained in step (A) is mixed with one or several monoisocyanates and (C) the mixture (B) thus obtained is subsequently reacted with one or several polymers (D) containing hydroxyl groups to form polyurethane resin (P). To produce the polyurethane resin, less than 20 wt. % in relation to the weight of the polyurethane resin (solid), polyalkylene oxide dipolyols and/or polyakylene oxide polyols are used.