Acid Polyamide Dyes

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). 

Acid—mordant dyes have characteristics similar to those of acid dyes which have a relatively low molecular weight, anionic substituents, and an affinity to polyamide fibers and mordant dyes. In general, brilliant shades caimot be obtained by acid—mordant dyes because they are used as their chromium mordant by treatment with dichromate in the course of the dyeing procedure. However, because of their excellent fastness for light and wet treatment, they are predominandy used to dye wool in heavy shades (navy blue, brown, and black). In terms of chemical constitution, most of the acid—mordant dyes are azo dyes some are triphenyhnethane dyes and very few anthraquinone dyes are used in this area. Cl Mordant Black 13 [1324-21 -6] (183) (Cl 63615) is one of the few examples of currentiy produced anthraquinone acid—mordant dyes. It is prepared by condensation of purpurin with aniline in the presence of boric acid, followed by sulfonation and finally by conversion to the sodium salt (146,147). 

Azo dyes with relatively low molecular masses and one to three sulfonic acid groups serve as acid azo dyes for dyeing and printing wool, polyamide, silk, and basic-modified acrylics and for dyeing leather, fur, paper, and food. The main area of application is the dyeing of wool and polyamide. 

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). 

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. 

The group includes many natural and synthetic dyes, the latter usually being obtained from anthracene. They have no natural affinity for textiles but are applied to cellulosic or protein fibres which have been mordanted previously with a metallic oxide. The acid mordant dyes are a special class of dyes applied to wool or polyamide fibres as if the were acid dyes, and then given very high wet-fastness by subsequent mordanting. 

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. 

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) ... 

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). 

Among these dye classes, anthraquiaone dyes are ia an important position ia reactive dyes and vat dyes for cellulose fibers, disperse dyes for polyester, and acid dyes for polyamide. Application for high performance organic pigments for plastics and paints are also important areas. 

Acid Dyes. These are anionic dyes, usually containing sulfonic acid groups, that are substantive to wool, other protein fibers, and polyamides when dyed from an acidic dyebath. The lower the pH the more rapid the dyeing, and exhaustion efficiency is enhanced by increased acidity. 

Direct Dyes. These are defined as anionic dyes, again containing sulfonic acid groups, with substantivity for ceUulosic fibers. They are usually a2o dyes (qv) and can be mono-, dis-, or polya2o, and are ia general planar stmctures. They are appHed to ceUulosic fibers from neutral dyebaths, ie, they have direct substantivity without the need of other agents. Salt is used to enhance dyebath exhaustion. Some direct dyes can be appHed to wool and polyamides under acidic conditions, but these are the exception. 

Nylon is similar ia its general chemical stmcture to the natural fiber wool, and therefore all the previously described processes for wool are appHcable to dyeiag nylon with acid, metallised, and other dyes. There are, however, significant differences. Nylon is synthetic, it has defined chemical stmcture depending on the manufactufing process, and it is hydrophobic (see Fibers, POLYAMIDES). 

Printing of wool or silk with acid dyes is of minor importance. For these fibers the print paste is made with dye solvent, humectant (glycerol and urea), a suitable thickener, and dilute organic acid. An oxidising agent is also added. Fixation follows the procedure for polyamide with fully saturated steam. 

Acid dyes can be ptinted on acetate, produciag prints with very good wetfastness and exceptional brightness. The print paste contains a solvent, urea, and ammonium thiocyanate, as a fiber swelling agent to aid ia diffusion of the dye. Again, fixation and scouting foUow the procedures for polyamide. 

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. 

The three most important types of synthetic fibres used commonly as textiles are polyester, polyamides (nylon) and acrylic fibres. Polyester and the semi-synthetic fibre cellulose acetate are dyed almost exclusively with the use of disperse dyes. Polyamide fibres may be coloured using either acid dyes, the principles of which have been discussed in the section on protein fibres, or with disperse dyes. Acrylic fibres are dyed mainly using basic (cationic) dyes. 

Azolides used as activators for sodium percarbonate/perborate in laundry bleaching,1261-1291 for decreasing the affinity of polyamide textile materials for acid dyes,1301 and as antiflammatory agents 1311... 

Aliphatic iodine derivatives, 14 376 Aliphatic ketones, 14 563, 571, 581-585 reactions of, 16 331-332 Aliphatic monothiopolyesters, 23 739 Aliphatic nitration, 12 187 Aliphatic peroxyacids, 13 464 Aliphatic peroxycarboxylic acids, 18 463 Aliphatic phosphines, 19 60 Aliphatic polyamides (PA), 10 207-210 19 713, 739. See also Aromatic polyamides PA entries producers of, 10 210 properties of, 10 208, 209t Aliphatic polycarbonates, 24 703 preparation of, 19 798 Aliphatic polyketones (PK), 10 197 costs of, 10 222 properties of, 10 198t Aliphatic poly(monosulfide)s, 23 702-704 Aliphatic polyphosphonate dyes, 9 480 Aliphatic poly(polysulfide)s, 23 711 Aliphatic polysulfides, 23 734 Aliphatic polysulfoxides, 23 733 miscibility of, 23 735 Aliphatic polyurea preparation, carbonyl sulfide in, 23 625... 

Superionic conducting glass systems, 12 586 Superior vena cava, 5 80 Super iron cells, 3 431t Superlattice(s), 13 499, 19 166 via MOCVD, 22 158-160 Superleaks, 17 354 Super Lewis acids, 12 191 Superluminscent LEDs, 22 176 Supermilling acid dyes, 26 396 Super milling dyes, 9 184, 185 Super-moire pattern, 17 428 Supermolecular organization, of polyamide fibers, 19 740... 

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