Vanillin, a potential carrier for low temperature dyeing of polyester fabrics

The potential use of vanillin for the chemical substitution of toxic carriers used in low temperature dyeing of polyester fabrics, was assessed. Both para and ortho-vanillin were used to compare the dyeing of a woven polyester fabric with two different blue disperse dyes: a high molecular weight anthraquinone dye D79 and a low molecular weight azoic dye D56. When 1 g of vanillin was used for dyeing with 3% of disperse dye, the dye uptakes increased for both vanillins, but were higher with ortho-vanillin especially in the case of the low molecular weight dye. The impact of different dyeing parameters such as pH, o-vanillin concentration and use of ethanol co-solvent, on the dye uptake was also studied. Highest dye uptake was reached with 2 g of ortho-vanillin at pH 7, without use of the co-solvent.Dye uptakes were compared to those of traditional carriers such as phenylphenol, dichlorobenzene, benzoic acid, and a commercial Levegal DTE carrier. With 2 g of vanillin, K/S of dyed fabric reached 16, which is equivalent to that obtained with 1 g of the commercial carrier. The study confirms that vanillin can be used as a chemical substitute to traditional carriers and leads to good wash and rub fastness properties.At present, few literature data are available to compare toxicity of all carriers and apply the principle of substitution. A toxicity analysis carried out using USEtox™ model showed that both para and ortho vanillins used in agro-food industries are not recognized as toxic for human health, unlike most traditional carriers. Ortho-vanillin has however high ecotoxicity.