Dyes on Polyamide Fibers

Dyeing Process. A dispersing agent is added to the liquor, and the pH is adjusted to 5 with acetic acid. The process is started with the material at 40°C and fol- 

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

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Improves wetfastness and crockfastness properties of acid, premetalized, and cationic dyes on polyamide fibers effective reserving agents for dyeing polyamide/cellulosic fiber blends. 

Lee, S.J., et al., 2006. Preliminary exhaustion studies of spiroxazine dyes on polyamide fibers and their photochromic properties. Dyes and Pigments 69, 18—21. 

Direct Dyes. A few selected direct dyes are used to complement the acid dyes ia printing of polyamide. Printing of ceUulosic fibers with direct dyes, as with acid dyes, has lost its importance owiag to iasufficient wetfastness properties of these dyes on ceUulosic fibers, and cumbersome fixation and scouting procedures. 

Practically all synthetic fibers can be printed with disperse dyes. Cationic dyes are used preferentially for acrylic fibers, and acid dyes and metal-complex dyes can be used for prints on polyamide fibers. The importance of printing with disperse dyes and the relative amount of different man-made fibers used for prints varies according to fashion and local requirements. Polyester fabrics alone or in combination with cotton are the most important. After precleaning, fabrics made from synthetic fibers must be heat-set to achieve dimensional stability and crease resistance. The usual setting conditions are 20-30 s at 190-210°C, and for texturized articles about 30°C lower. 

The adsorption isotherms of acid azo dyes onto water soluble and insoluble polymers containing cyclodextrin were measured in aqueous solution. The adsorption of dyes on both types of polymers increased with increase in the ratio of hydrophobic components in the dyes [38], Dyes derivative of dialkylaminobenzene were used for the dyeing of nylon 6 and 6,6 in the presence of interacting / -CD [39], / -CD showed good levelling properties in the dyeing of polyamide fibers. The observed effect can be due to the formation of complexes between /Acyclodcxtri n and dyes. 

Savarino, P. Parlati, S. Buscaino, R. Piccinini, P. Degani, I. and Bami, E. (2004) Effect of additives on the dyeing of polyamide fibers. Part I. / -Cyclodextrin, Dyes and Pigments 60, 223-232 and papers cited therein. 

Uses Dispersant applied in the alkaline reduction dear after treatment of dyeings with disperse dyes on polyester fibers antipredpitant antistat on polyamide ftroperfies Liq. 

Uses Leveling agent for cationic dyes on syn. fibers antistat for acrylics, polyamides, and acetate fibers Properties Liq. water-sol. 

Synthetic organic pigments, 19 418-422t history of, 19 423-424 Synthetic organic polymers, manufactured fibers based on, 24 616-618 Synthetic polyamide fibers, dyeing, 9 188-191, 469-470... 

Sokolowska-Gajda, J., Freeman, H.S. and Reife, A. (1994) Synthetic dyes based on environmental considerations 1. Iron complexes for protein and polyamide fibers. Text. Res. f, 64 (7), 388-396. 

Dyes for Cellulose Ester and Synthetic Polyamide Fibers. The first disperse dyes were developed for dyeing cellulose fibers, but the importance of these diminished considerably when other synthetic fibers appeared on the market. Synthetic polyamide fibers could be dyed with dyes used for acetate fibers very few new dyes had to be developed specifically for polyamide fibers. 

The basic type of dye closely resembles that used for dyeing polyester fibers, but the selection of compounds is based on other criteria. Requirements regarding sublimation resistance are not as stringent, whereas fastness to ozone, exhaust gases, and washing are important. Substitution by amino, and especially by alkyl-amino, groups tends to decrease lightfastness of the dyes in polyester fibers. This is not the case for acetate and polyamide fibers. 

Sulfur dyes of the Indocarbon type (C.I. Sulphur Black 6, 53295 [1327-16-8], C.I. Sulphur Black 7, 53300 [1327-17-9] and C.I. Sulphur Black 11, 53290 [1327-14-6]) are also used for printing on these fibers. Sulfur dyes find limited use with polyamide fibers, silk, leather, paper, and wood. 

Reactive Dyes on Wool, Silk and Polyamide Fibers... 

Elastomeric polyurethane fibers [96, pp. 609-615], are contained in stretch articles and in knitted fashion materials. Light shades can be dyed tone-on-tone on polyamide-polyurethane mixtures with disperse dyes at 95-98°C and pH 6-7. However, the wetfastness of these dyeings on polyurethanes is lower than on polyamide. Because of the temperature sensitivity of polyurethane fibers, mixtures of elastomeric and polyester fibers must be dyed with small-molecular, rapidly diffusing disperse dyes in 30 min at 120 °C according to the HT process [148], Modified PES fibers that are dyeable at 100°C without a carrier are often used in mixtures with elastomeric fibers. In all dyeing processes for elastomeric fibers, dyeing equipment that permits low-strain guidance of the material and the lowest possible thermal stress are important. 

Disperse Dyes Nonionic dyes insoluble in water and used mainly as fine aqueous dispersions in dying acetate, polyester, and polyamide fibers. A large subclass of disperse dyes comprises low-molecular-weight aromatic azo compounds with amino, hydroxy, and alkoxy groups that fix on fibers by forming van der Waals and hydrogen bonds. 

FIGURE 14.2 Reaction schemes between polyamide fiber and textile dyes based on the isoelectric point (pH 4.2), (a) below the isoelectric point, and (b) above the isoelectric point. (Reprinted from Akbari, A., Remigy, J.C., and Aptel, R, Chem. Eng. Process., 41, 601-609, 2002. With permission.)... 

Figure 14.17 shows the elliptical regions of uncertainty for the fibers shown in Figure 14.18. The fiber here is a round polyamide type treated with different dispersive dyes. Figure 14.19 shows an example of an error or uncertainty ellipse in more detail. When a fiber is treated with a single colorant, the centr axis of the uncertainty ellipse generally points toward the coordinates of the undyed fiber. This observation is attributed to the depth of penetratiim of tiie dye varying from fiber to fiber. In other words, the fiber "starts" at the undyed position on the chromaticity diagram. The more of a single dye that is accepted by tile fiber, the deeper the color is and the farther the chromaticity coordinates shift away from e undyed fiber color. Taken to the extreme, this line would extend to coordinates of the pure dye. Because different individual fibers have different dye uptake characteristics, some fibers will take on more dye and some less, even when made of the same polymer in the same batch.

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