Abstract: Cationic modifier Color Media was applied in modification of cotton fabric, and then the influences of process conditions such as modifier dosage, dyeing temperature, dyeing time and dyeing liquor ratio on dyeing modified cotton fabric were analyzed. The dyeing effect of modified cotton fabric and unmodified cotton fabric were compared. The process of salt-free direct dye dip dyeing of modified cotton fabric was optimized, and the optimal process conditions were as follows: modifier dosage 3%（o.w.f）, dyeing temperature 90℃ dyeing time 50 min and dyeing liquor ratio 1∶30, when the dosage of direct dye was 1%（o.w.f）. The results indicated that cotton fabric modified with Color Media featured high K/S value, similar washing and rubbing fastness to those of traditional dyeing, and the salt-free dip dyeing was viable and practical.

Key words: cotton fabric; cationic modifier; direct dye; dip dyeing