Part 2: Cationization of Cotton Bedsheet Fabrics by Pad-Batch Method

Cotton is the most widely used fibre in manufacturing, which, being negatively charged, requires various electrolytes to be dyed with negative dyestuffs. These electrolytes cause a large environmental waste water load and unfortunately many of them are released into the environment after waste water treatment. It seems possible to overcome this problem by cationization cotton. This research paper is a two-part study. In the first part of the paper has two sections. The initial section of this paper, 100% cotton terry towel fabrics were subjected to cationization procedures during and after the bleaching process in a laboratory setting, utilizing six distinct commercial cationization agents by using exhaustion method. The cationized cotton terry towel fabrics were then subjected to dyeing procedures: salt-free reactive dyeing, conventional reactive dyeing and acid dyeing. The CIELAB values, rubbing and washing fastness, and colour strength (K/S) of the fabrics were then compared. Subsequently, a decision analysis study (analytical hierarchical process, AHP) was conducted to identify the optimal cationization agent and processes for big commercial-scale applications. The criteria included color strength, color fastness, and cationic agent cost. In light of the findings of the AHP studies, CA1 coded cationization agent (based on polyammonium compounds) was identified as the optimal cationic agent for utilization in commercial dyeing, the specifics of which will be outlined in the subsequent paper. Moreover, the findings indicated that cationization should be carried out after bleaching. The second section of the paper presents the results of big commercial scale cationization, reactive and acid dyeing's carried out using the selected cationization agent and exhaustion processes. The influence of these processes on the properties of fastness (perspiration, wash, and water fastness) and physical characteristics (tensile strength and water absorption) of cotton terry towel fabrics was evaluated by statistical comparison. The chemical oxygen demand, ammonium nitrogen, total chemical, energy, and water consumption of the commercially available dyes were also compared to assess their environmental impact. The second part of the study examined the cationization of cotton fabrics used for bed sheets - an important home textile product - using the pad-batch method, followed by dyeing. The weaving of fabrics generally occurs in an open-width configuration, wherein the fabric is spread out during the weaving process. This characteristic renders pad-batch dyeing processes particularly well-suited for the treatment of woven fabrics. It may be concluded that rope dyeing is not a common practice when it comes to woven fabrics. Rope dyeing has been observed to result in the formation of crease marks and uneven dyeing on woven fabrics. The first part of the article provides a detailed exposition of the cationization and dyeing of towel fabrics through the utilization of the rope dyeing method (exhaustion). The second part elucidates the cationization and dyeing of bed sheet fabrics employing the open-width dyeing method (pad-batch). The CIELAB values, rubbing and washing fastness, and colour fastness (K/S) values of the cotton bed sheet fabrics were statistically compared. The statistical analysis indicated that cationic agents and dyeing types exerted a statistically significant effect on K/S. In a similar manner, the quantity of cationic agent had a significant effect on the K/S values.

Furthermore, the batching time subsequent to the dyeing process resulted in significant important effect in the K/S values of the fabrics. The factor groups that ensure the colour strength value remains at its optimal (maximum) level are, in order: cationic agent; CA1 coded cationization agent (based on polyamine compounds), cationic agent amount; 5g/l and a waiting (batching) time of 8 hours. In view of the findings, the following conclusions can be drawn with regard to reactive dyeing by pad-batch method: the optimum values in terms of environmental aspects and dyeing can be accepted as 5 g/l of CA1 cationic agent and 8 hours batching.