Crosslinking nucleophilic dyes on wool

Nucleophilic amino-alkyl dyes have been synthesised by the simple expedient of reacting existing reactive dyes with ethylene diamine. These dyes when applied to wool behave as acid dyes, although there is a small amount of covalent bonding to the fibre, presumably through Michael addition at dehydroalanine residues formed from cystine degradation.

If substantive crosslinking agents could be applied then it might be expected that excellent dye-fibre covalent bonding could be achieved to produce dyeings with very high wet fastness properties. The crosslinking agent might be added either before, during or after the amino-alkyl dye application; the latter procedure should, in principle, give the most level dyeings. Crosslinking agents evaluated include hexamine, triacroylamino-hexahydro-s-triazine, methylene-bisacrylamide and 2-chloro-4.6-di(aminobenzene-4′-sul-phatoethylsulphone)-s-triazine. Hexamine and methylene-bisacrylamide are available commercially but the other agents were synthesised. Results obtained are very promising and offer potential wool dyeing methods which have better levelness than existing reactive dye systems.