Stainproofing agent and process for its preparation

A process for preparing a stainproofing agent, which comprises

• reacting a mixture of polyfunctional isocyanate compounds having at least three --NCO groups and a --NHCON<
• bond derived from an addition reaction of a >H--N group-containing compound III with a --NCO group-containing compound IV, wherein the compound III is derived from OCH--Y--NCO, wherein Y is selected from the group consisting of --(CH.sub.2).sub.6 -- and ##STR47## and the compound IV is OCN--Y--NCO or derived from OCN--Y--NCO where Y is as defined above,
• with a compound of the formula R.sub.f --X--A--H wherein
• R.sub.f is a polyfluoroalkyl group having from 1 to 20 carbon atoms,
• X is --R--, --CON(R.sup.1)--Q-- or --SO.sub.2 N(R.sup.1)--Q--,
• wherein R is alkylene, R.sup.1 is a hydrogen atom or a lower alkyl group and Q is a alkylene, and
• A is --O--, --S-- or --N(Z')-- wherein Z' is a hydrogen atom or a lower alkyl group, and, if required, further reacting the mixture with a compound of the formula Z--A'--H, wherein A'--Z is selected from the group consisting of ##STR48## --OR', --OCH.sub.2 CH.sub.2 CN, --OCH.sub.2 CH.sub.2 NO.sub.2, --OCH.sub.2 CH.sub.2 OH, --NHCH.sub.2 OH, --NHCH.sub.2 CH.sub.2 OH, ##STR49## --NHR', --NR'R', --N(CH.sub.2 CH.sub.2 OH).sub.2 and ##STR50## where R' is an alkyl group, to form a mixture of polyfluoroalkyl containing compounds having at least one --NHCO--A--X--R.sub.f group
• wherein
• A, X and R.sub.f are as defined above,
• having a molecular weight of at most 8000 and,
• if required, at least one --NHCO--A'--Z group wherein A'--Z is as defined above, provided that the total of the --NHCO--A--X--R.sub.f groups and the number of --NHCO--A--Z groups is at least three.