Dye baths

The appearance of streaks with leveling or nonleveling acid and premetallized dye can be subdued by increasing the dye-bath pH from 5.5 to 6—7, at a sacrifice ia dye exhaust, by a dding chemical agents that retard the dye strike or, more effectively, by metering all or a portion of the dye ia a concentrated solution at or near the dyeiag temperature of the fiber (87.8—104.4°C) iastead of at the usual 26.7—48.9°C practiced by the trade (178). 

For end uses demanding high dye lightfastness such as automotive iaterior fabrics, select premetallized dyes and uv inhibitors are appHed through the dye bath (179—182). Nylon can also be codyed with polyurethane elastomeric fibers, wool, acryflcs, polyesters, and ceUulosics (183). 

Ammonium acetate has limited commercial uses. It serves as an analytical reagent, and in the production of foam mbber and vinyl plastics it is also used as a diaphoretic and diuretic in pharmaceutical appHcations. The salt has some importance as a mordant in textile dyeing. In a hot dye bath, gradual volatilization of ammonia from the ammonium acetate causes the dye solution to become progressively more acidic. This increase in acidity enhances the color and permanence of the dyeing process. 

Dye formation is complex because shading is achieved by employing several developers and several couplers in the same dye bath. The process is illustrated by -phenylenediamine, which is oxidized by the peroxide to a quinone diimine. This short-Hved intermediate can react, for example, with resorcinol to yield a brownish indoaniline. Table 17 provides some insight into the many interactions that exist from just a few components. Further shading is possible by including semipermanent colorants (see Table 16), especially nitroaniline derivatives. 

In 1958, Hoechst introduced the vinyl sulfone reactive dyes, offered as the sulfatoester from which the reactive vinyl sulfone group was generated in the alkaline dye bath. 

Amines or amides Alkyl amines (iindecyloctyl and diamyl methyl amine) polyamides (acyl derivatives of piperazine) Boiler foam sewage foam fermentation dye baths... 

Farb-abanderung, /. change in color. ab-streichrakel, m. /. color doctor, -abstu fung, /. color gradation. anstrich, m. coat of color, coat of paint, -bad, n. dye bath, band, n. typewriter ribbon. 

Farber-erde, /. Armenian bole, -flechte, /. archil, dyer s moss, -flotte, /. dye liquor, dye bath, -ginster, m. dyer s broom (Ge-niata tinctoria). -holz, n. dyer s wood, dye-wood. 

Flotte, /. liquor specif, dye liquor, dye bath fleet, navy. 

Staffel,/, step round, rung stage squadron, staffieren, v.t. trim, equip prepare (a dye bath). 

For the characterization of compounds extracted from plants, wool and dye baths, acquisition in the NI mode is used. The main signals in the mass spectra of each colourant are attributed to deprotonated molecular ions [M H]. More detailed studies can be performed by ESI MS" with a quadrupole ion trap mass analyzer, and such a set-up was used e.g. for the investigation of photo-oxidation processes of components of weld and onion skins.[29]... 

Golab V, Vinder A, Simonic M (2005) Efficiency of the coagulation/flocculation method for the treatment of dye bath effluent. Dyes Pigm 67 93-97... 

Carliell CM, Barclay N, Buckley CA (1996) Treatment of exhausted reactive dye bath effluent using anaerobic digestion laboratory and full-scale trials. Wat SA 22 225-233... 

Nitrate is normally found in textile processing wastewaters and generally comes from salts such as sodium nitrate, which is included in the dye baths for the improvement of dye fixation to the textile fibers. Nitrate concentrations used in textile processing can reach 40-100 g/L [35], The importance of nitrate in anaerobic phase of SBR is that nitrate can compete with the azo dye for reducing the equivalents formed, resulting in decreasing decolorization [2, 5, 7, 35, 36], Wuhrmann et al. [5] reported that azo dye cannot be decolorized until denitrification ends up. 

Like nitrate, sulfate is also a constituent of textile processing wastewaters. Sulfate is generally added to the dye baths for ionic strength adjustment or it may be formed by the oxidation of sulfur species used in dyeing processes, such as sulfide, hydrosulfide, and dithionite [37]. 

Rai HS, Singh PPS, Cheema TK et al (2007) Decolorization of triphenylmethane dye-bath effluent in an integrated two-stage anaerobic reactor. J Environ Manage 83 290-297... 

As earlier noted, PET has no dye attachment sites for chemically active dyes. It is possible to add ionic dyeability by forming copolymers of PET with monomer species that possess active sites, for example, on a pendant side chain. The most common of these has been the incorporation of a sodium salt of a dicarboxylic acid, e.g. of 5-sulfoisophthalic acid (Figure 12.14). The acidic sulfo group allows the attachment of cationic dye molecules. If both the modified and the unmodified fibers are put into a dye bath containing a mixture of disperse and cat dyes, they will emerge with two different colors. This is useful in the creation of specialty fabrics, e.g. when two different dye types are woven into fabrics with a predetermined pattern. The multicolored pattern emerges upon dyeing. 

Much effort has been devoted to the applicaton of electrophoretic techniques for the analysis of dyes and dye decomposition products in industrial waste-waters. CZE with DAD and MS detection was employed for the determination of reactive dyes in spent dye-baths and waste-waters. The chemical structure of the dyes included in the experiments are shown in Fig. 3.149. Liquid samples were purified and preconcentrated by SPE. ODS cartridges were conditioned by washing with two bed volumes of methanol, four bed volumes of water and two bed volumes of 5 mM tetrabutylammonium phosphate. Aliquots of 10 - 30 ml were loaded and the cartridges were washed with 2 ml of water. Analytes were eluted with 2 ml of methanol-water (70 30, v/v). Untreated fused-silica capillaries (110 cm and 57 cm X 50 /im i.d.) were coupled to MS and DAD. The running... 

T. Poiger, S.D. Richardson and G.L. Baughman, Identification of reactive dyes in spent dye-baths and wastewater by capillary electrophoresis-mass spectrometry. J. ChromatogrA, 886 (2000) 271-282. 

Cellulosics are easily coloured, suitable for dyeing by immersion in dye baths, and can be solvent polished, cut, cemented, drilled and decorated. Varnishing and serigraphy are easily used. 

Contrary to other synthetic fiber materials, polypropylene fibers cannot be colored by contacting them with an aqueous solution or dispersion of organic dyes. Due to its highly apolar nature, polypropylene is not able to interact with conventional dye molecules, so that it cannot take up any dye from the dye bath. 

---