Polyisocyanate solutions useful for impregnating porous inorganic substrates

摘要

Solutions of a) a fluorine-containing polyisocyanate in b) an isocyanate-inert solvent are used to impart water, oil and dirt resistance to porous inorganic substrates impregnated therewith. The fluorine-containing polyisocyanate is preferably selected from fluorine-containing polyisocyanates having a fluorine content in the form of perfluorinated alkyl groups of from about 15 to about 60% by weight and an isocyanate content of from about 0.5 to about 15% by weight. These isocyanates are obtained by reaction of (cyclo)aliphatic isocyanates with fluorine-containing mono- and polyhydric alcohols, and selected fluorine-containing alcohols suitable for the production of these polyisocyanates.