Fiber Reactive Dyes with Improved Affinity and Fixation Efficiency

Abstract

Although fiber reactive dyes are widely used in the dyeing of cellulosic materials, several economical and environmental problems are associated with their application. Problems include residual color in wastewater, cost of wastewater treatment, raw material cost (salt, dye, and water), and quality of goods produced are examples of areas where improvements are needed. The afforementioned costs could be reduced by increasing the fixation efficiency and exhaustion of reactive dyes. In turn, fixation efficiency and exhaustion could be increased by increasing dye-fiber affinity.

This thesis pertains to an evaluation of four types of dye structures arising from novel but straightforward modifications of commercially available fiber reactive dyes to produce colorants designated by Proctor and Gamble as Teegafix Reactive dyes. Teegafix dyes are produced in 2 steps from dichlorotriazine (DCT) type reactive dyes, using either cysteamine or cysteine and then reacting the intermediate structures with either cyanuric chloride (cf. Type 1 and 2 yellow dyes) or a second molecule of the starting dye (cf. Types 3 and 4 yellow dyes). In the same way, red and blue DCT dyes were converted to the corresponding Teegafix structures. The resultant homobifunctional dyes vary in molecular size and reactivity and are designed to enhance dye-fiber fixation efficiency and affinity.

In this study, the affinity of the new structures has been assessed using equilibrium exhaustion and dyeing experiments. Equilibrium exhaustion experiments were conducted on the four dye types at two temperatures and four salt concentrations. Types 2 and 4 dyes had a greater affinity on cotton than the corresponding commercial dyes. These two dye types were examined further in dyeing experiments.

Laboratory dyeing experiments were conducted on the commercial dyes and the type 2 and 4 dyes. These experiments included an assessment of the effects of temperature, salt, dye concentration, and alkali. Increased affinity was observed as increased fixation levels for the Teegafix dye structures. Physical testing was also conducted on the dyed fabric samples, including crockfastness, wetfastness, and lightfastness. There were no significant decreases in the performance properties of the Teegafix dyes when compared to the commercially available dyes.