Sodium chloride/potassium chromate cooxidant induced concurrent desizing, scouring and bleaching of cotton and cotton/polyester blend fabrics

A novel chemical formulation for simultaneous bleaching of cotton and its blend with polyester was established. Thus, loomstate cotton and cotton/polyester blend fabrics were independently padded in a solution containing NaClO2 and K2CrO4 along with non-ionic wetting agent at certain pH to a wet pick-up of ca. 80%. The fabric was then exposed to 90°C in a Launder Ometer(R) for a certain duration, followed by washing and drying. The critical properties of the fabric, such as whiteness index, loss in weight, wettability, tensile strength, copper number, and carboxyl groups were found to depend upon the concentration of NaClO2 and K2CrO4, as well as the pH of the treating bath and duration of the treatment. The results obtained indicated that a treating formulation consisting of NaClO2 (20 g/l), K2CrO4 (3 g/l) or NaClO2 (30 g/l), K2CrO4 (1 g/l) at pH6 for 90 minutes at 90°C is appropriate for concurrent desizing, scouring, and bleaching in the case of cotton. For cotton/polyester blend, on the other hand, the optimum treating formulation consisted of NaClO2 (20 g/l), K2CrO4 (3 g/l) at pH6 for 60 or 90 minutes at 90°C.