| abstract |
Aqueous dispersions composed of polycarbodiimides which carry substantially no carboxyl groups and I are obtained from polyisocyanates of the formula I <?in-line-formulae description="In-line Formulae" end="lead"?>OCN-(R<SUP>c</SUP>-N-C-N)<SUB>n</SUB>-R<SUP>c</SUP>-NCO (I) <?in-line-formulae description="In-line Formulae" end="tail"?> where R<SUP>c </SUP>is a divalent hydrocarbon radical with or without urea, urethane, ester and/or ether groups, as is obtained by removal of the isocyanate groups from a simple organic isocyanate or from a prepolymer which contains urethane groups and, if desired, ether or ester groups and which carries terminal isocyanate groups, two or more radicals R<SUP>c </SUP>present in the same molecule having identical or different definitions, and n being from 1 to 20, or II are of the formula (II) <?in-line-formulae description="In-line Formulae" end="lead"?>R<SUP>d</SUP>-(R<SUP>c</SUP>-N-C-N-R<SUP>c</SUP>)<SUB>n</SUB>-R<SUP>d </SUP>(II) <?in-line-formulae description="In-line Formulae" end="tail"?> where n is a number from 1 to 20, R<SUP>c </SUP>is as defined for the formula (I), R<SUP>d </SUP>is -NH<SUB>2 </SUB> and R<SUP>e </SUP>independently at each occurrence is C<SUB>1 </SUB>to C<SUB>20 </SUB>alkyl or alkenyl, C<SUB>5 </SUB>to C<SUB>12 </SUB>cycloalkyl, C<SUB>6 </SUB>to C<SUB>20 </SUB>aryl or C<SUB>7 </SUB>to C<SUB>20 </SUB>aralkyl, in which 1 to 4 hydrogen atoms of the radical R<SUP>e </SUP>may be substituted by substituents that are inert toward carbodiimide groups and in which the radical R<SUP>e </SUP>ought not to contain any hydrophilic groups capable of producing dispersibility in water. |