Layered clay aqueous dispersion as a novel dye leveling agent in leather processing: Synthesis, characterization and application studies

• LDH-based dye leveling agent, was developed & used in leather dyeing.
• Leathers with excellent color uniformity/consistency were obtained by using LDH.
• LDH facilitated retaining the chemical composition of the leather after dyeing.
• Dyeing of leather using LDH reduced exhaust of dye and chromium in the effluent

Dyeing is an important process step of leather manufacture that is performed to obtain intended final color. Intensity variation and inconsistency in color characteristics among leathers processed in a batch are major concerns of tanners. Variations in final leather color result in either rework or rejection of leather leading to significant productivity and economic loss. Moreover, to produce certain natural-look leather products, uniform dyeing of the entire leather surface and color uniformity of the leathers among each batch are an absolute necessity. In this study, an aqueous dispersion of layered double hydroxide (LDH) has been synthesized and used as dye leveling agent in leather dyeing operation to enhance the shade intensity of the leather and color uniformity among different pieces of leathers. The physico-chemical characteristics of the LDH dispersion in water and its efficacy towards achieving the objective have been studied. Leathers processed using the aqueous dispersion of LDH showed excellent color uniformity and consistency with no detrimental effect on color fastness characteristics of the leather.

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