They are——-eval(ez_write_tag([[468,60],'textilestudycenter_com-leader-4','ezslot_15',198,'0','0'])); The step in which the reduction of the dyestuff into its leuco-form takes place is called vatting. Although their function is to assist effectively the adsorption and fixation of the dyes into the fibres, they are unlikely to be consumed completely during the dyeing process and hence, may lead to pollution load on rinsing the dyed material using large amounts of water. Kerosene in pigment printing causes air pollution. Application of the soluble dye to the textile material, i.e. This is referred to as bio-elimination. This technology consists of special pad troughs with an optimised shape and efficient double flow bath circulation. Vat dyes have always been very expensive compared with other dye classes and are used for high-quality products only. So used in curtain. Now, we’re going to discuss how vat dyes are applied on cotton. (2002). One component of these is hydrophobic (D-part) and non-polar fibre while the other is hydrophilic and polar (A-part). First vatting process is done then it can apply on textile materials for dyeing purpose. The smaller the size of the particles, the more easily the dye gets reduced. . • most commonly (Na2S2O4) it’s helps to convert easily in leuco form. • The presence of little excess reducing agent, which is a must, can be tested by vat yellow paper in dyebath. Dyes are costly, but the levelling property is excellent. In this case, first required vatting for making it solubilized form. The process should be run at 60-70ºC for 30 minutes. The typical chemica l structures of vat dyes are given in Fig. First things first, we need to know how the name came into being. There is no effective and economic way to control this pollution load other than either to use less or to opt for ecofriendly substitutes. Required fields are marked *. Vat dyes are natural coloring dyes. The main difference between vat and reactive dyes is its application process. Vat dyes have always been very expensive compared with other dye classes and are used for high-quality products only. Later, slaked lime Ca(OH)_2 was added to dissolve indigo white, which in turn produced the yellow solution that was used for dyeing . Table 16.8. They represent a wide variety of chemical types. Both the semi-continuous methods can be applied to dye yarn in a yarn package-dyeing machine. ETAD has established limits for the content of heavy metal in dyestuffs. Shore, J., & Society of Dyers and Colourists (Eds.). Vat dye are insoluble in water but with the help of vatting process vat dye is easily soluble in water. This is usually accomplished by placing the cellulosic fibre in an oxidizing bath. The I stands for Indanthrene and has been a trademark for vat dyes since the synthesis of indanthrone, and the name Indanthrene has been used as a synonym for vat dyes since then. Typical problems are associated with use of Na2S2O4 and NaOH in vat dyeing, Na2S in sulphur dyeing, NaOH and NaCl in reactive dyeing, use of K2Cr2O7, Na2Cr2O7, CuSO4 in direct and sulphur dyeing, copper complex in phthalogen blue dyeing, resins used to after-treat direct dyeing etc. The vat acid process is marked by the rapid speed of development, which cuts down the bleeding of dyeing in the developing bath. • in case of vat dyeing, vatting process is necessary to required before dyeing. These small ions enter the fibre quickly, and the pigment form of the vat dye is locked in the fibre both mechanically and through secondary or hydrogen bonding. Polyester is dyed with disperse dye and cellulose is dyed with vat, direct, reactive, sulphur, solubilised vat or insoluble azoic colours.
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