Polyurethanes

摘要

Hydroxyl-containing polyurethanes I are composed essentially of a) a diisocyanate of 6 to 30 carbon atoms (component II), b) a component III comprising alpha ) an aliphatic diol of 2 to 20 carbon atoms or beta ) an aromatic-aliphatic or aromatic-cycloaliphatic diol of 8 to 30 carbon atoms having nonphenolic hydroxyl groups as hydroxyl groups of the diol and c) a polyhydric alcohol having at least 3 hydroxyl groups, 3 to 18 carbon atoms and nonphenolic hydroxyl groups as hydroxyl groups of the alcohol (component IV), the amounts of components II to IV being such that the total number of nonphenolic hydroxyl groups is from 1.1 to 5.0 per isocyanate group of II. The polyurethanes can be used as binders or binder components for pigment-containing coatings, in particular for the production of magnetic recording materials.