Acid Milling dyes

Acid milling dyes have medium neutral affinity and dyeing can commence on neutrally charged wool. If excess positive charges exist then rapid absorption and unlevel dyeing result. Usually acetic acid is sufficient to generate the requisite number of sites. 

Acid milling dyes are intermediate in behavior being appHed with acetic or formic acid in the presence of sodium sulfate. 

Acid milling dyes are intermediate in behavior, being applied with acetic or formic acid in the presence of sodium sulfate. A disadvantage or acid dyes is that I heir wetfastness depends on the Formation and maintenance or a salt linkage between the charged wool and dye. This requires an acidic inlemal pH to be maintained in the wool. 

These acid dyes, applied from a neutral liquor, arc colloidally dispersed in solution at lower temperatures, although it is probable that the majority of them assume a state of molecular dispersion at temperatures near the boil. They are not level-dyeing and their application demands a considerable measure of care. They are often referred to as the fast acid dyes or the acid milling dyes because, originally, they were used in cloths which were to be milled. They are also sometimes called the neutral dyeing acid dyes. They possess good light- and wet-fastnesses as shown in Table 15.5. 

The aim of washing off is to remove the thickener and any residual chemicals and imfixed dye from the fabric, without causing staining of any pale or unprinted areas. Fabrics printed with metal complex or acid milling dyes are usually washed off in water at 30-40°C, whereas reactive dyes require higher temperatures (60-80°C), with addition of ammonium hydroxide (120). 

The dyes used on wool can be divided into the following groups acid dyes, chrome dyes, premetallized dyes and reactive dyes (88,89,92—94,97—99). Strictly speaking, all types of wool dyestuffs can be described as acid dyes, but in practice this term is confined to leveling acid dyes, half-milling dyes, milling dyes, and supermilling dyes (94,97). This subclassification of acid dyes arises out of the methods used for their appHcation and their fastness properties on wool. 

Glasses. There are three classes of acid dyes acid leveling, acid milling, and super milling. 

These dyes are not very commercially important, and the dyeing mechanism has been described in detail elsewhere (15,25). The difficulty in applying fiber-reactive dyes to wool is the result of the same reactions already described. They are negatively charged and the wool is positively charged so ionic attraction exists. The fiber-reactive dyes are essentiaUy acid leveling or milling dyes and so this attraction can be controUed by pH. Once the dye is fixed no... 

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... 

Monosulphonated dyes of Mr 500-600 are somewhat more hydrophobic than the monosulphonated levelling acid dyes. They also migrate and cover well but they are a little inferior to disulphonated milling dyes in wet fastness and thus have sometimes been described as half-milling dyes ... 

Milling dyes with very good wet fastness are obtained by the reaction of one mole of a diamine with two moles of bromamine acid, as in the case of Cl Acid Blue 127 (6.35). This dye is suitable for dyeing wool bright blue from a neutral or weakly acid bath. 

Dyes used Acid, milling, chrome, mordant, vat, and indigo. 

Group C contains the milling dyes, which are applied in a weakly acid to neutral bath. 

Primary disazo dyes of the type K <—D —>K2 (Ki = K2 or K i K2). This series includes many milling dyes because of the molecular size achieved (group C). Depending on the type of coupling components Ki and K2, which may be phenols, pyrazolones, acetoacetic acid arylamides, or naphtholsulfonic acids, clear yellow to red shades are obtained. For a long time the preferred diazo components were diaminodiphenyl derivatives, such as benzidine, o-tolidine and o-anisidine. They are now of no further importance because of their carcinogenic potential. 

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