Polyamide Dyeing

T.A. Beerman, and P.B. Dervan. Cellular uptake of N-methylpyrrole/N-methyli-midazole polyamide-dye conjugates. 

The main area of application for the acid polyamide dyes of group A is in carpet dyeing, but they are also used in other areas of textile dyeing where the fastness requirements are not too stringent. A few structures are presented below to illustrate the types of azo dyes used C.I. Acid Yellow25, 18835 [6359-85-9] (31), C.I. Acid Red 42, 17070 [6245-60-9] (32), C.I. Acid Red 32, 17065 [6360-10-7] (33). 

Wool and Polyamide Dyes. Water-soluble formazan complexes having sulfonamide, alkylsulfonyl, or sulfonic acid groups possess a high affinity to nitrogen-containing fibers. As with acid dyes, they can be used to dye wool and polyamide in neutral to weakly acid baths. Commercial dyes of this type are C.I. Acid Blue 267 and 297, and the 1 2 cobalt complex C.I. Acid Black 180, 13710 [11103-91-6] (29). 

For the technological aspects of polyamide dyeing, see also Section 4.11.4. 

Derivatives of Aroilenbenzimidazoles Dyes for Polyamides Dyeing in Mass... 

Patent of FRG No 1903244. Method of synthetic linear polyamide dyeing in mass (1978) (in Russian). 

Because of the substantial scatter of the degree of elimination it is advisable in critical cases to determine P-values experimentally in simulated systems or from field measurements. In an ETAD-project [11] P-values have been determined by Zahn-Wellens measurements but such values have to be considered as worst-case situations because test conditions require relatively high soluble dye concentrations in relation to the amount of suspended sludge [11], Furthermore, P-values are pH-dependent and can be determined from adsoiption isotherms. In the case of wool and polyamide dyeing, P-values can be estimated from the data on fixation (F), due to the similarity of the surface functional groups of sludge particles to those of the textile substrate. 

The study of reuse of wastewater generated in the dyeing of nylon-6,6 fabrics and treated by adsorption process with rylon-6,6/chitosan (80/20) blend flakes were carried out. The efficiency in color removal of the adsorption process varied between 97 and 98% with exception of yellow erinoyl effluents which gave 65%. The reuse of treated wastewater from polyamide dyeing imder the tested condition is feasible although with some restriction for yellow especially (Barcellos et al., 2008). 

Inorganic pigment dispersant— photographic films Emulsifier—latex polymerization Ag halide emulsion stabilizer Thickeners, emulsifiers Cellulose nitrate latex stabilizer Inorganic pigments dispersant— photocopying Textile finishes dispersant Dispersant, thickeners polyamide dyes... 

Quality Specifications. Because of the extreme sensitivity of polyamide synthesis to impurities ia the iagredients (eg, for molecular-weight control, dye receptivity), adipic acid is one of the purest materials produced on a large scale. In addition to food-additive and polyamide specifications, other special requirements arise from the variety of other appHcations. Table 8 summarizes the more important specifications. Typical impurities iaclude monobasic acids arising from the air oxidation step ia synthesis, and lower dibasic acids and nitrogenous materials from the nitric acid oxidation step. Trace metals, water, color, and oils round out the usual specification Hsts. 

Dyes, application and evaluation). Foi dyeing fibei blends such as viscose—polyamide, polyamide—Spandex, oi polyestei—cotton, only compatible FWAs may be used that do not inteifeie with one another oi have any detrimental effect on fastness properties. 

New water-insol. naphthalic acid imide dyestuffs - used to dye blends of polyamide or urethane- and polyester or tri acetate fibres having good light and washing fastness C91-110.342 RICH DE GB LI) ... 

Sulfur dyes are used mainly for dyeing textile ceUulosic materials or blends of ceUulosic fibers (qv) with synthetic fibers such as acryUc fibers, polyamides (nylons), and polyesters. They are also used for sHk (qv) and paper (qv) in limited quantities for specific appHcations. Solubilized sulfur dyes are used on certain types of leathers (qv). 

Other disazo dyes with good substantivity and high wet-fastness properties on polyamides are Acid Red 114 (40), made by coupling o-toHdine to phenol which is then coupled to G-acid, followed by reaction of the phenoHc hydroxyl group with -toluenesulfonyl chloride, and Acid Blue 113 (41) (metanilic acid — 1-naphthylamine — 8-anilino-1-naphthalenesulfonic acid). 

Different polyamide fibers with varying affinities for anionic dyes are pretreated with aqueous acidic solution containing sulfated castor od to give uniform shade levels. Sulfated castor od is also used in compositions for treatment of fabrics, skins, and furs to clean and revive colors (115). 

It is difficult for dye solutions in water to penetrate synthetic fibers such as polyester, cellulose triacetate, polyamides, and polyacryUcs which are somewhat hydrophobic. The rate of water imbibition differs with each fiber as shown in Table 1 as compared to viscose (see Fibers, regenerated CELLULOSics), which imbibes water at the rate of 100% (1). The low imbibition rate is attributed to the high T obtained when the polymeric fibers are drawn. During this drawing operation the polymer chains become highly oriented and tightly packed, forming a stmcture practically free of voids. 

Disperse dyes are water-iasoluble, aqueous dispersed materials that are used for dyeiag hydrophobic synthetic fibers, including polyester, acetate, and polyamide. 

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