Effect of Different Types Scouring against Different Types of Bleaching Process on Dyeing of Cotton Fabric with Monochlorotriazine (Hot Brand) Reactive Dye

摘要

Bleaching is the removal of unwanted colour from the textile fibres and typically involves the use of one of the four main bleaching agents, namely sodium hypochlorite, calcium hypochlorite, sodium chlorite and hydrogen peroxide. Cotton must be properly prepared for dyeing, printing and finishing. To prepare the cotton fabric for dyeing, printing and finishing process scouring & bleaching is the fundamental step. Prior to bleaching, most of the impurities present in the cotton material are removed by pressure boil under alkaline conditions. The H_(2)O_(2) bleaching is the most common bleaching method, and is environmentally friendly (degradable into water and oxygen). The best bleaching whiteness can be obtained at pH 11 adjusted using caustic soda. When dyeing is performed without a drying process after the H_(2)O_(2) bleaching, the problem of residual H_(2)O_(2) arises. 10ppm of residual H_(2)O_(2) or more causes dyeing problems, bleaching is used for destructing of natural coloring matters to impart pure permanent and basic white effects suitable for the production of white finishes, level dyeing and desired printed shade.