Rendering Viscose Fabrics Dye-able with Basic and Acid Dyes Using Citric Acid and Chitosan Nano Particles Based Finishing Formulation

Abstract

ABSTRACT The innovation anticipated here is the use of our previously prepared chitosan nanoparticles in conjunction with citric acid and sodium hypophosphite for rendering viscose fabrics dyed and finished concurrently in one step with dual classes of dyes, namely basic and acid dyes, using a pad-dry-cure process. This was done to see the effect of the aforementioned eco-friendly finishing formulation on creating dual anchoring sites onto finished fabrics for dye-ability using Basic Red 2 and Acid Orange 7, which have no direct affinity to viscose fabric. So, different concentrations of CA, CNPs, and dyes were mixed into a viscose fabric cross-linking formulation together with a set concentration of SHP (50% based on weight of CA concentration) and cured at 170°C for 2 minutes. Citric acid is predicted to react with the hydroxyl groups in viscose and CNPs to produce ester crosslinking and/or to form an inter-ionic attraction with the amino groups of CNPs. The latter was responsible for viscose fabrics dye ability with Basic Red 2 by anchoring the free carboxyl groups in citric acid, as well as their dye ability with Acid Orange 7 by anchoring the residual amine groups in CNPs.