Thermal and photochemical stabilisation of dyeings on polyamide fibres: application of sulfonated hindered phenolic derivative

A process for improving the thermal and/or photochemical stability of dyeings on polyamide fibres, which process comprises applying to said polyamide fibres, from an aqueous medium, a compound of formula (1)

• (A--Y--).sub.n Z(--W).sub.m ( 1)
• wherein
• A is the radical of a sterically hindered phenol of the benzene series
• Y is a radical of formula (2) or (3) ##STR63## wherein X and X' are each independently of the other alkylene, oxaalkylene or thiaalkylene, R.sub.2 and R.sub.3 are each independently of the other hydrogen or an unsubstituted or substituted alkyl group, and x, x' and y are each independently of the other 0 or 1,
• Z is an aliphatic or a carbocyclic aromatic radical, which last mentioned radical contains not more than two mono- or bicyclic nuclei,
• W is a sulfo group, and
• m and n are each independently of the other 1 or 2, or a water-soluble salt thereof,
• wherein the compound of formula (1) goes on to the fibres by an exhaust or continuous dyeing process.