Substantive dyes

Diptam, m. (Bot.) dittany, direktfilrbend, a. direct-coloring, direct. Direktfarbstoff, m. direct dye. substantive dye. Direktive,/. instructions, dlrektziehend, a, (Dyeing) direct. 

Emulsion thickeners can be mixed with low concentrations of either natural or synthetic thickeners, especially when applying fibre-substantive dyes rather than pigments these additions act as film formers, taking the place of the binder used with pigments to increase retention of the dye by the substrate prior to fixation. 

The ability to adopt an extended configuration has been recognised for many years to be a desirable feature of substantive dyes. It helps to explain why J acid is such a popular choice as a central component in unsymmetrical disazo dyes. For example, it is much easier for aniline—>] acid—>H acid (3.61) with the 2,6-naphthylene substitution pattern to adopt a linear conformation than for the similar disazo dyes aniline—acid— H acid (3.62) and aniline—>H acid—>J acid (3.63) with 2,7- and 2,8-disubstitution respectively. 

Notes Col. 1. — (i) PE-PSSA polystyrene sulphonic acid grafted onto a polyethylene matrix and containing indicated amounts of divinyl benzene 120) (ii) Ionac MC-3470 (Ionac Corp., USA) powdered mixture of PSSA ion exchanger and inert polymer compressed hot with embedded mesh of supporting material120) (iii) Cellophane PUT 600/23 sheet (British Cellophane Ltd.) washed to remove plasticizer110) (iv) Dye A C. I. Direct Blue 1 (tetrasulphonate substantive dye)110 (v) Dye B Procion Yellow HA (disulphonate reactive dye, I.C.I. Ltd.)121. ... 

Direct or substantive dyes are colored compounds that are mainly used to dye materials made from natural or regenerated cellulose (e.g., cotton, jute, viscose, or paper) without employing mordants as auxiliaries. The essential requirement for classification of a dye in this group is its substantivity, i.e., its absorption from an aqueous salt-containing solution onto cellulosic materials. Absorption onto cotton takes place in a neutral to soda alkaline medium, and onto paper in a weakly acid to neutral medium. 

Only then is diffusion into the fiber possible. The tendency toward aggregation is therefore characteristic of substantive dyes, which also explains why coplanar dyes possess greater substantivity than nonplanar ones. 

Coupling diazotized dehydrothio-p-toluidinesulfonic acid to resorcinol and subsequent coupling of diazotized aniline to the monoazo dye formed gives C. I. Direct Orange 18, 20215 [5915-59-3] (11), an important substantive dye. 

Alkaline condensation of dinitrostilbenedisulfonic acid with aminoazo compounds produces a number of highly fast substantive dyes with industrial importance, especially in the shades orange, scarlet, and brown [6], Example C. I. Direct Orange 39, 40215 [1325-54-8] (for synthesis, see Section 3.3.4). 

The introduction of copper into conventional substantive dyes often increases their light and wetfastness considerably, since complexing blocks the hydrophilic groups. Copper complexes of o,o -disubstituted azo dyes are chiefly of interest for direct dyes. Substituents especially capable of complexing are hydroxyl, meth-oxy, carboxy, and carbomethoxy groups. BASF developed the oxidative copper treatment process in which on the basis of o-hydro xyazo dyes, copper complexes of the corresponding o,o -dihydroxyazo dyes are obtained [9],... 

There are a number of yellow substantive dyes synthesized by this principle. Example C. I. Direct Yellow 41, 29005 [8005-53-6] (29) is obtained by phosgene treatment of an equimolar mixture of bases A (sulfanilic acid— cresidine) and B (jt>-nitroaniline—> salicylic acid and reduction of the N02 group). The mixture additionally contains the two corresponding symmetrical dyes. 

Aftertreatment of substantive dyeings with cationic organic substances has lately begun to gain in importance. Improvements are obtained in particular in wetfastness properties, especially fastness to water, washing, and wet pressing, as well as fastness to perspiration and cross-dyeing. 

The water-soluble resins are inexpensive, and compared with quaternary ammonium compounds relatively small quantities often suffice to achieve a marked improvement in wetfastness and fastness to perspiration. A disadvantage is a certain influence on lightfastness. This may be lowered by one to two steps on the eight-step blue scale when these resins are used on materials dyed by substantive dyes. Formaldehyde condensation resins are therefore used especially for articles in which wet fastness and fastness to perspiration are important, but light fastness is less crucial, e.g., lining fabrics. 

Azo dyes with several cationic charges, which are substantive dyes for cellulose, are increasingly being used for coloring bleached sulfite cellulose. 

Dyes bearing one or more dialkylaminoalkyl substituents are use for coloring paper because they behave as substantive dyes which, when properly substituted, result in a practically colorless waste liquor. A suitable starting material for the preparation of such dyes is the reaction product of 2 mol dialkylaminopropylamine with 1 mol cyanuric chloride. This can he converted to an acetoacetarylide, which when coupled with diazotized 2-(4 -aminophenyl)-5-methylbenzothiazole, yields the yellow dye 3 [91458-38-7] with greenish cast suitable for coloring paper [8],... 

By coupling to derivatives of I acid, substantive dyes (e.g., 31) are obtained in which the charge on the sulfonic acid group is more than compensated for by the multiple cationic charges. These dye paper in shades of red [87],... 

Disazo and polyazo dyes containing sulfonic acid groups are also frequently used in the above applications. Many of them are also sold as substantive dyes for cotton because of their pronounced affinity toward cellulosic fibers (see Section 3.3). 

Copper-containing substantive dyes such as 21 C.I. Direct Blue 93, 22810 [13217-74-8] have long been used for coloring cotton [34],... 

Among metal-complex dyes only the planar 1 1 copper complexes exhibit sufficient substantivity to dye paper, whereas the octahedral 1 2 chromium and cobalt complexes are unsuitable for this purpose. Cationic substantive dyes, such as the bis-copper complex 26 [45] provide the most colorless effluent waters and superior fast paper dyeings that do not bleed out upon contact with milk, fruit juice, or alcohol [46],... 

In the exhaustion dyeing process, highly or moderately substantive dyes are usually employed. The optimum dyeing conditions depend on the reactivity of the dyes. Cold dyers are dyed at 30-50°C and a pH of 10-11 hot dyers at 70-90°C and a pH of 11-12. For pH control normally mixtures of sodium carbonate and sodium hydroxide are used. To enhance substantivity of the dye sodium sulfate or sodium chloride is added. For less than 0.5 % dye based on textile weight, salt concentrations of 10-30 g/L are recommended. For deep shades (more than 4%), ca. 50 g/L is used with vinylsulfone dyes having low substantivity, up to 80 g/L. 

When selecting dyes, the dyer must consider the possibility of so-called tailings. This refers to differences in shade and depth of shade between the beginning and end of the batch of fabric. With highly substantive dyes, the liquor running back into the padder from the squeezing rollers has a lower dye concentration than the initial liquor. This causes a gradual depletion of dye in the liquor. 

In contrast to some naturally occurring dyes like indigo or kermes, which must be vatted or mordanted to be applied in textile dyeing, direct or substantive dyes can be used on cellulosic fibers directly . Their use is widespread because of their easy handling. Today, direct dyes still account for ca. 10% of the world textile dye consumption. For use on paper, see Section 5.3. Recent research on direct dyes concentrated on the replacement of possibly carcinogenic benzidine dyes [44],... 

This is an important class of dyes for the dyeing of paper. Direct dyes are also called substantive dyes [4,5] because they tend to have a high affinity to cellulose fibers due to their linear molecular structure and a system of conjugated double bonds and usually also exhibit good wetfastness properties with the addition of a fixative. 

CASSOFIX TW is a cationic aftertreating agent that markedly improves the wet and perspiration fastness of direct colors (substantive dyes) on cotton, rayon, or other cellulosic fibers. 

BURCOFIX FR-30 is a resinous, cationic substantive dye fixative that gives good fixation of direct colors with reduction of bleeding and crocking. 

Appearance clear, yellowish, slightly viscous liquid Chemical nature resinous, cationic substantive dye fixative pH on dilution 3.0-4.0 Density 1.130 (9.38 Ibs/gal)... 

A resinous substantive dye fixative, cationic in nature and considered to be in the durable categories. This material is used in the fixation of direct dyestuff and fiber reactives having a minimum effect on shade to give good dye fixation to wet bleeding and laundering. 

The dyeing of cotton fiber is accomplished by three principal processes. Cotton may be chemically reacted with fiber-reactive dyes in solution. The dyeing takes place by reaction with hydroxyl groups in cotton. A second method is the use of substantive dyes that diffuse directly into fiber from a dye solution. The dyeing rate is increased by the addition of electrolytes. The third method is referred to as mordant dyeing in which the dye in solution reacts with metals previously applied to the fiber to form insoluble colored compounds on the cotton. Vat dyes are another important class of dyes for cotton. These are applied in a soluble reduced form and after application they are oxidized, forming an insoluble molecule [8]. 

Congo red is a representative of a group of dyes known as substantive dyes which are able to dye cotton without the use of a mordant. It is of special interest historically as it was the first dye of this group to be made. 

Benzo purpurin.— Tolidine is di-methyl benzidine, that is it bears the same relation to toluene and ortho-toluidine that benzidine does to benzene and aniline. When this is diazotized and the tetrazonium salt coupled with sodium naphthionate the disazo compound resulting is a dye known as benzopmpurin 4B, which is also a substantive dye of a red color. 

This dye is not a substantive dye. It dyes wool a blue black color. 

Two theories as to the nature of substantive dyeing have been advanced, a chemical and a mechanical theory.-... 

Another conclusiqp which follows from the researches of the same chemist, is that many cases of so-called substantive dyeing are in reality adjective. In the case of wool, for example, a compound has been isolated, called lanuguinic acid, and it has been found that this acid is capable of entering into combination with dyestuffs, producing compounds which, although amorphous, closely... 

Azo dyes based on the aromatic intermediate benzidine were invented in 1884. These were the first synthetic dyes that adhered to cotton fabrics without the need for a fixing agent (mordant). For this reason they were known as direct or substantive dyes. The first member was discovered by Paul Bottiger, at Bayer. From benzidine (25) and naphthionic acid (20) he obtained a red bisazo dyestuff (26)41 see Scheme 9. 

However, many problems remained, including the need to deal with speculative patents. In 1884, AGFA filed a patent for the substantive dye Congo red (26). It was soon followed... 

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