Fiber reactive dyes

Fiber optics cables Fiber optic waveguides Fiber-reactive dyebath Fiber reactive dyes... 

A series of fiber-reactive dyes have been made by the reaction of Sulforhodamine B with chlorosulfonic acid, an appropriately substituted diamine, and cyanutic chloride to yield dyes, eg, a Sulforhodamine B derivative (34), with good hghtfastness (42). 

For fluorine-free products, the labiUty of fluorine in fluoronitrobenzenes and other activated molecules permits it to serve as a handle in hair-dye manufacturing operations, high performance polymers such as polyetheretherketone (PEEK), production of dmgs such as diuretics, and fiber-reactive dyes. Labile fluorine has also been used in analytical appHcations and biological diagnostic reagents. 

FLUOROPYRIMIDINES Fluoropyrknidines find diverse use in cancer chemotherapy and other dmg appHcations, as well as in fiber-reactive dyes. Table 13 fists physical properties of representative fluoropyrknidines. 

Chloro-2,4,6-trifluoropyrimidine [697-83-6] has gained commercial importance for the production of fiber-reactive dyes (465,466). It can be manufactured by partial fluoriaation of 2,3,5,6-tetrachloropyrimidine [1780-40-1] with anhydrous hydrogen fluoride (autoclave or vapor phase) (467) or sodium fluoride (autoclave, 300°C) (468). 5-Chloro-2,4,6-trifluoropyrimidine is condensed with amine chromophores to provide the... 

FLUOROTRIAZINES Riag-fluoriaated triaziaes are used ia fiber-reactive dyes. Perfluoroalkyl triaziaes are offered commercially as mass spectral markers and have been iatensively evaluated for elastomer and hydraulic fluid appHcations. Physical properties of representative fluorotriaziaes are listed ia Table 13. Toxicity data are available. For cyanuric fluoride, LD g =3.1 ppm for 4 h (iahalatioa, rat) and 160 mg/kg (skin, rabbit) (127). 

Fiber-reactive dyes containing the fluorotriaziayl group are based on the condensation of chromophores containing amino groups with 6 - sub s titute d- 2,4- diflu o r o triaziae s. The latter can be prepared from cyanuric fluoride or from the reaction of alkah metal fluorides with... 

Many aminonaphthalenesulfonic acids are important in the manufacture of azo dyes (qv) or are used to make intermediates for azo acid dyes, direct, and fiber-reactive dyes (see Dyes, reactive). Usually, the aminonaphthalenesulfonic acids are made by either the sulfonation of naphthalenamines, the nitration—reduction of naphthalenesulfonic acids, the Bucherer-type amination of naphtholsulfonic acids, or the desulfonation of an aminonaphthalenedi-or ttisulfonic acid. Most of these processes produce by-products or mixtures which often are separated in subsequent purification steps. A summary of commercially important aminonaphthalenesulfonic acids is given in Table 4. 

Dyes, Dye Intermediates, and Naphthalene. Several thousand different synthetic dyes are known, having a total worldwide consumption of 298 million kg/yr (see Dyes AND dye intermediates). Many dyes contain some form of sulfonate as —SO H, —SO Na, or —SO2NH2. Acid dyes, solvent dyes, basic dyes, disperse dyes, fiber-reactive dyes, and vat dyes can have one or more sulfonic acid groups incorporated into their molecular stmcture. The raw materials used for the manufacture of dyes are mainly aromatic hydrocarbons (67—74) and include ben2ene, toluene, naphthalene, anthracene, pyrene, phenol (qv), pyridine, and carba2ole. Anthraquinone sulfonic acid is an important dye intermediate and is prepared by sulfonation of anthraquinone using sulfur trioxide and sulfuric acid. 

Sulfonic Acid-Based Dyestuffs. Sulfonic acid-derived dyes are utilized industrially in the areas of textiles (qv), paper, cosmetics (qv), foods, detergents, soaps, leather, and inks, both as reactive and disperse dyes. Of the principal classes of dyes, sulfonic acid derivatives find utiUty in the areas of acid, azoic, direct, disperse, and fiber-reactive dyes. In 1994, 120,930 t of synthetic dyes were manufactured in the United States, of which 5,600 t were acidic (74). The three largest manufacturers of sulfonic acid-based dyes for use in the United States are BASF, Bayer, and Ciba-Geigy. 

From an appHcations point of view, the sulfur dyes are between vat, direct, and fiber-reactive dyes. They give good to moderate lightfastness and good wetfastness at low cost and rapid processing (see Dyes, application and evaluation). 

Fiber-Reactive Dyes. These dyes can enter iato chemical reaction with the fiber and form a covalent bond to become an iategral part of the fiber polymer. They therefore have exceptional wetfastness. Thein main use is on ceUulosic fibers where they are appHed neutral and then chemical reaction is initiated by the addition of alkaH. Reaction with the ceUulose can be by either nucleophilic substitution, using, for example, dyes containing activated halogen substituents, or by addition to the double bond in, for example, vinyl sulfone, —S02CH=CH2, groups. 

Covalent Bonds. Fiber-reactive dyes, ie, dyestuff molecules containing reactive groups, are adsorbed onto the fiber and react with specific sites (chemical groups) in the fiber polymer to form covalent bonds. The reaction is irreversible, so active dye is removed from the equiUbrium system (it becomes part of the fiber) and this causes more dye to adsorb onto the fiber to re-estabflsh the equiUbrium of active dye between fiber and aqueous dyebath phases (see Dyes, reactive). 

Because of the limitations of direct dyes and the abiHty to use simple acid dye chromophores to give bright washfast dyeings, fiber-reactive dyes have become a weU-estabHshed, popular way of dyeing cellulose. A market of 56,000 t of reactive dyes was forecast for cellulose fibers in 1989 (18), and the growth rate of reactive dye consumption of 3.9% per annum is four times the growth rate of other dyes for ceUulosic fibers (19). 

Fiber-reactive dye is also hydrolyzed by reaction with free OH ions in the aqueous phase. This is a nonreversible reaction and so active dye is lost from the system. Hydrolysis of active dye can take place both in the dyebath and on the fiber, although in the latter case there is a competition between the reactions with free hydroxyl ions and those with ionized ceUulose sites. The hydrolyzed dye estabHshes its own equUibrium between dyebath and fiber which could be different from the active dye because the hydrolyzed dye has different chemical potentials in the two phases. The various reactions taking place can be summarized as in Figure 2. 

Basic Theory of Fiber-Reactive Dye Application. The previously described mechanisms of dyeing for direct dyes apply to the apphcation of reactive dyes in neutral dyebaths. In alkaline solutions important differences are found. The detailed theoretical treatments are described elsewhere (6) but it is important to consider some of the parameters and understand how they influence the apphcation of fiber-reactive dyes. 

With the addition of increasing amounts of electrolyte this variance decreases and an approximate linear relationship between internal and external pH exists in a 1 Af electrolyte solution. The cell-0 concentration is dependent on the internal pH, and the rate of reaction of a fiber-reactive dye is a function of cell-0 (6,16). Thus the higher the concentration of cell-0 the more rapid the reaction and the greater the number of potential dye fixation sites. 

Electrolyte therefore plays three important roles increasing absorption in the neutral state, preventing desorption/promoting secondary exhaustion, and increasing the amount of ioni2ed ceHulose. Thus the amounts of salt used in the apphcation of fiber-reactive dyes are larger than for direct dyes. 

The Ideal Fiber-Reactive Dye Profile. Eigure 3 shows the general profile for the apphcation of a reactive dye. In addition to showing the rate profile of fixation between dye and fiber, three other practical parameters (A—C) are noted. 

Eig. 3. Amounts and forms of fiber-reactive dye on the fiber as a function of time for a low affinity dye, where X represents the reactive group. Point A represents the amount of dye exhausted in neutral conditions B is the total amount of dye exhausted at the end of the dyeing process, ie, [dye—OH] +... 

Cold Exhaust Dyeings Fiber-Reactive Dyes. Start at 25—30°C optionally with a sequestrant and maintain. The dye is added over 5 min, then there is portionwise addition of salt every 10—15 min, increasing the size of the addition each time over 1 h. The amount of salt used (10—100 g/L) depends on the depth of shade. After the final addition of salt, wait 15 min, portionwise add soda ash (10—20 g/L) over 15 min, and continue dyeing for 30—45 min. Drop dyebath, cold water rinse, and use a sequence of hot washes to remove all loose "unfixed" dye. 

Correlation of Application, Affinity, and Reactivity. Eigure 4 correlates fiber-reactive dye appHcation suitabiHty to reactivity and... 

DYEING WOOL WITH FIBER-REACTIVE DYES... 

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... 

These methods 2, J, and 4) are only used when applyiag fiber-reactive dyes. In all methods thermofixation conditions are 60—90 s at 190—220°C depending on the choice of disperse dye. In method (/) the chemical pad is caustic and hydrosulfite for vat dyes, and alkaU and salt for fiber reactives. This is the most popular method ia the United States. 

In method (2) the fiber-reactive dye is appHed with alkaH. The choice of alkaH and batching times and temperature are dependent on the fiber-reactive dye used. 

FiaaHy, ia method (4) the fabric is padded with a mixture of medium energy disperse dyes, carehiUy selected higher reactivity, and rapid diffusiag fiber-reactive dyes, up to 10 g/L sodium bicarbonate depending on depth of shade, and proprietary auxiHary agents. 

Resist Printing. In resist printing, print pastes are used that can inhibit the development or fixation of different dyes that are apphed to the textile prior to or after printing. These resists can be of a chemical or mechanical nature, or combine both methods. For example, fiber-reactive dyes, which require alkaU for their fixation, can be made resistant by printing a nonvolatile organic acid, such as tartaric acid, on the textile. Colored resists are obtained by printing pigments with a nonvolatile acid. 

Relative strength determination by solution measurement is difficult in the case of vat and sulfur dyes and leads to unreflable results in cases where some of the dye in the commercial product has no affinity for the fiber such as for certain direct and fiber-reactive dyes. 

Table 3. Reactive Groups in Fiber-Reactive Dyes...

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