Bisulfite-blockled polyisocyanates as tanning agent

PURPOSE: To provide a tanning agent of bisulfite-blocked polyisocyanates for use as an alternative to mineral oil tanning agents or in a preliminary stage of vegetable or other tanning treatment. CONSTITUTION: This tanning agent having a carbamoyl sulfonate group is prepd. by reacting an org. polyisocyanate (A), a polyether alcohol (B) having incorporated therein polyalkylene oxide units with 40 to 100 mol.% thereof being accounted for by polyethylene oxide units having a sequence length of 5 to 70, the amt. of the polyether alcohol being 0.01 to 0.4 equivalent relative to the isocyanate group of the polyisocyanate (A) (the equivalents of the polyether alcohol being based on the hydroxyl groups), an optional NCO reactive component (C) other than the polyether alcohol (B), and an ammonium or alkali bisulfite or disulfite (D). COPYRIGHT: (C)1996,JPO