Urea/alkali‐free printing of cotton with reactive dyes

Abstract

Urea reduction or elimination in reactive dye print pastes is of ecological interest. Sodium edetate is presented as a complete substitution of urea in the conventional print paste of reactive dyes, namely CI Remazol Black B and Remazol Brilliant Orange 3R using a constant amount of sodium alginate as the thickening agent. Three different print pastes containing urea/NaHCO 3 , sodium edetate/NaHCO 3 and sodium edetate were thoroughly investigated. Different factors that may affect the printability of cotton, such as the concentrations of sodium edetate, urea, dye, absence or presence of alkali and steaming time in the prints obtained were evaluated with respect to the dye fixation, colour strength, dye penetration, levelling and the fastness properties. Excellent to good fastness was obtained for all samples irrespective of the print paste used.

The inkjet printing process for Lyocell and cotton fibres. Part 1: The significance of pre-treatment chemicals and their relationship with colour strength, absorbed dye fixation and ink penetration

“…In the case of cotton, the reduced fixation at higher levels of urea correlates as expected with the observed reduction in colour strength. There has been some industrial interest in minimizing the use of, or replacing, urea as an auxiliary in textile processing for environmental reasons [28,29]. This present study is useful in demonstrating how the level of urea may be controlled to provide a balance which maximizes efficiency and cost-effectiveness (colour strength and dye fixation) while minimizing environmental effects.…”

Treatment of cotton printing and dyeing wastewater by supercritical water oxidation

“…The organic nitrogen in dyeing wastewater is derived from the dyes with nitrogenous substituting groups, such as azo group, amino group, nitro group or Ncontaining heterocycle, and urea used as cellulose printing auxiliary. The functions of urea during the application of reactive dyes have been found to be an increase in the solubility of dye in the reaction medium, dye disaggregation, retardation of water evaporation during drying and swelling of cotton, thereby facilitating the dye-fiber reaction [15]. However, the use of urea has caused ecological problems associated with the high nitrogen content in the printing effluent.…”

Rheological studies of mixed printing pastes from sodium alginate and modified xanthan and their application in the reactive printing of cotton

“…In the textile industry, cotton is one of the major fibres, and more than 70% of all printed substrates are cellulosic fabrics . Moreover, reactive dye printing is the most commonly used method after pigment printing.…”