Ink-jet printing of cellulosic fabrics with reactive dyes typically requires that the fabric is pretreated with alkali, prior to printing, to facilitate efficient fixation of the dye. In this paper we evaluate the use of sodium formate and other carboxylate salts as a neutral (pH 6.5) pretreatment process. The thickened, prepared-for-print pad liquor contained at least 50 gdm⁻³ of the selected carboxylate salt and was applied to the cotton fabrics by a pad-dry procedure. The fabric was then ink-jet printed with reactive dye inks, followed by standard steaming and washing-off processes. The pH of the carboxylate salt pretreatment was 6.5 and the aqueous extracts from the print fabrics at the end of the steaming process remained at pH 6.5. It was observed that even at pH 6.5, in the presence of selected carboxylates, significant reactive dye fixation could be achieved on a cotton substrate, whereas in the absence of the carboxylate, very little or even zero fixation was achieved. Infrared and capillary electrophoresis analyses of model reactions of reactive dyes with the carboxylate salts indicated that reactive ester residues were formed, and which subsequently promoted reaction with the cellulosic substrates. In addition to improving reactive dye fixation in ink-jet printing, the carboxylate-modified dyes were also demonstrated to improve long-liquor dyeing properties on cotton substrates. As an extension of this carboxylate-based printing process, the incorporation of lithium acetate (100 gdm⁻³) into the ink formulation was further studied and it was demonstrated that the necessity for a preparative pretreatment process could be eliminated.

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活性染料与羧酸盐反应的研究及羧酸盐改性活性染料在棉花上的应用

用活性染料对纤维素织物进行喷墨印花通常需要在印花前用碱对织物进行预处理，以促进染料的有效固色。在本文中，我们评估了使用甲酸钠和其他羧酸盐作为中性 (pH 6.5) 预处理工艺。增稠的准备印刷的移印液含有至少 50 gdm ^-3选择的羧酸盐的一部分，并通过浸轧干燥程序施加到棉织物上。然后用活性染料墨水对织物进行喷墨打印，然后进行标准的汽蒸和水洗工艺。羧酸盐预处理的pH为6.5，并且在汽蒸过程结束时来自印花织物的水提取物保持在pH 6.5。据观察，即使在 pH 6.5 下，在存在选定的羧酸盐的情况下，也可以在棉基材上实现显着的活性染料固色，而在没有羧酸盐的情况下，实现非常少甚至零固色。活性染料与羧酸盐的模型反应的红外和毛细管电泳分析表明，形成了活性酯残基，随后促进了与纤维素底物的反应。除了改善喷墨印花中的活性染料固着性外，羧酸盐改性染料还被证明可以改善棉基材上的长液染色性能。作为这种基于羧酸盐的印刷工艺的延伸，醋酸锂（100 gdm^-3 ) 进入油墨配方的进一步研究表明，可以消除对制备预处理过程的必要性。