Process for the preparation of modified fiber material and process for the dyeing of the modified fiber material with anionic textile dyes

A process for dyeing a fiber material with a water-soluble, anionic dye, which comprises the steps of providing a dye solution which contains from 0 to 10 g/l of electrolyte salts;

• said dye solution further containing alkali in an amount to give a pH of from 4 to 8, and
• providing a natural or synthetic fiber material containing hydroxy or carboxamide groups or a combination thereof, which natural or synthetic fiber material has been modified by being brought into contact with an alkaline aqueous solution and a compound which contains a saturated aliphatic radical of 3 to 15 carbon atoms which is unsubstituted or substituted by 1 or 2 or more hydroxy groups and contains at least one primary, secondary or tertiary amino groups or quaternary ammonium group and at least one hydrolyzable ester group, the saturated radical(s) being straight-chain, branched or cyclic or a combination thereof and may be interrupted by one or more hetero groups, with the exception of compounds of the formula (A)
• (H.sub.2 N).sub.p -ALK-ER (A)
• in which p is the number 1 or 2, ER is an ester group and ALK is an unsubstituted straight-chain or branched alkylene of 2 to 6 carbon atoms which may be interrupted by 1 or more hetero groups, and
• dyeing said fiber material with said dye solution.