Dye dispersants

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. 

Sodyevat vat, sulfuri2ed vat dyes, dispersed form Clariant Corp. United States... 

Blues are the single most important color in the disperse class, both in terms of amounts produced and doUar sales volume. Among all dyes. Disperse Blue 79 (100) (6-bromo-2,4-dinitroaniline [1817-73-8] coupled to 3-bis-(2-acetoxyethyl)-amino-/)-acetophenetidine [20249-05-2]) was the highest volume dye in the late 1980s and continues. As reported in 1985, the United States produced 2872 tons valued at 7.7 million. 

Manufacturing procedures for producing dye dispersions are generally not disclosed. The principal dispersants in use include long-chain alkyl sulfates, alkaryl sulfonates, fatty amine—ethylene oxide condensates, fatty alcohol—ethylene oxide condensates, naphthalene—formaldehyde—sulfuric acid condensates, and the lignin sulfonic acids. 

Fig. 4. Carbocychc azo dyes. Disperse Yellow 3 [2832-40-8] (Cl 11855) (26) is used to dye polyester Reactive Orange 1 [6522-74-3] (Cl 17907) (27) is a cotton dye Direct Orange 26 [25188-23-2] (Cl 29150) (28) is a dye for paper Synacril Fast Red 2G [48222-26-0] (Cl 11085) (29) dyes acrylic fibers Acid...

Preparation of Dispersion. The reduction process is a two-phase reaction between soluble reducing agent and insoluble dye particles, and therefore the rate of reduction is influenced by the particle size distribution of the dye dispersion. The smaller the particle size the greater the surface area and hence the more rapid the reduction process. However, if the particles are too small, migration will occur in continuous dyeing. It is therefore extremely important to control the size and range of particle size and this is a closely guarded piece of dyestuff manufacturers know-how. 

The majority of vat dyes used worldwide are appHed by continuous dyeing polyester—cotton blends are the most important substrate. The fabric is padded with vat dye dispersion, dried, padded with sodium hydrosulfite, caustic soda, and salt, steamed for 30—60 s at 102°C, rinsed, and dried. 

The process of textile print coloration can be divided into three steps. First, the colorant is appHed as pigment dispersion, dye dispersion, or dye solution from a vehicle caUed print paste or printing ink, containing in addition to the colorant such solutions or dispersions of chemicals as may be required by the colorant or textile substrate to improve and assist in dye solubUity, dispersion stabUity, pH, lubricity, hygroscopicity, rate of dye fixation to the substrate, and colorant-fiber bonding. The required viscosity characteristics of a print paste are achieved by addition of natural or synthetic thickening agents or by use of emulsions. 

Transfer printing employs the intermediate step of printing dye dispersions or dye solutions onto a temporary substrate, usually paper. From the paper, the dye is transferred to the textile by heat and steam, while printed paper and textile are in close contact. The advantages and limitations of the process have been described (33). 

Disperse Dyes. Disperse dyes are used in powder or paste form, or ready-to-prepare aqueous dispersions for incorporation into a thickener solution. Eor disperse dyes that show sensitivity to alkaline hydrolysis or reduction during fixation, an acid donor or acid, and, if necessary, a mild oxidizing agent, are added to the print paste. 

A study of the degradation of two azo disperse dyes. Disperse Orange 5 [6232-56-0] (1) Cl 11100) and Disperse Red 5 [3769-57-1] Cl 11215) showed reduction of the azo linkage into aromatic amines and further dealkylation to -phenylene-diamine [106-50-3] (2) (255). 

The fate of one dye that has been thoroughly studied in the a2o dye Disperse Blue 79 [12239-34-8] (6) (Cl 11345) which may be designated 6-bromo-2,4-dinitro-aniline—>3-(Al,A/-diacetoxyethylamino)-4-ethoxyacetanihde (see Azodyes). 

Summarizing, once this system has reached dynamic equilibrium, molecules continue to leave the liquid phase for the gas phase, but the liquid captures equal numbers of molecules from the gas. The amount of water in each phase remains the same (equilibrium) even though molecules continue to move back and forth between the gas and the liquid (dynamic). As with dye dispersed in water, no net change occurs after equilibrium is established. 

The traditional use of dyes is in the coloration of textiles, a topic covered in considerable depth in Chapters 7 and 8. Dyes are almost invariably applied to the textile materials from an aqueous medium, so that they are generally required to dissolve in water. Frequently, as is the case for example with acid dyes, direct dyes, cationic dyes and reactive dyes, they dissolve completely and very readily in water. This is not true, however, of every application class of textile dye. Disperse dyes for polyester fibres, for example, are only sparingly soluble in water and are applied as a fine aqueous dispersion. Vat dyes, an important application class of dyes for cellulosic fibres, are completely insoluble materials but they are converted by a chemical reduction process into a water-soluble form that may then be applied to the fibre. There is also a wide range of non-textile applications of dyes, many of which have emerged in recent years as a result of developments in the electronic and reprographic... 

Weber EJ, Adams RL (1995) Chemical- and sediment-mediated reduction of the azo dye disperse blue 79. Environ Sci Technol 29 1163-1170... 

Biomass from an anaerobic digester Reactive dyes disperse dyes Fixed bed with recycle and fixed bed Continuous Anaerobic B Reticulated sintered glass n.a. 37 6.4-7.2... 

All azo dyes contain one or more azo groups (-N=N-) as chromophore in the molecule on the basis of the number of azo groups in each molecule, they are named monoazo-, disazo-, trisazo-, etc. The azo groups are in general bound to a benzene or naphthalene ring, but they can also be attached to heterocyclic aromatic molecules or to enolizable aliphatic groups. On the basis of the characteristics of the processes in which they are applied, the molecule of the dye is modified to reach the best performances so they can be acid dyes, direct dyes, reactive dyes, disperse dyes, or others. 

J Kido, H Shionoya, and K Nagai, Single-layer white light-emitting organic electroluminescent devices based on dye-dispersed poly(Y-vinylcarbazolc), Appl. Phys. Lett., 67 2281-2283, 1995. 

It was pointed out in Chapter 1 that, after the azo class, anthraquinone derivatives form the next most important group of organic colorants listed in the Colour Index. The major application groups are vat dyes, disperse dyes and acid dyes (Table 1.1). 

The first CEM system described by Griffing and West (84) consisted of an organic dye dispersed in an inert polymer film that is spin coated onto the surface of a resist and subsequently removed following exposure but prior to resist development. The chemistry of this system is based on the photoisomerization of an aromatic dye to an oxaziridine (87) (Figure 10). Other workers have evaluated polysilanes (88) and diazonium salt chemistry (89,90) for CEM applications. 

Internal circulation patterns have been observed experimentally for drops by observing striae caused by the shearing of viscous solutions (S7) or by photographing non-surface-active aluminum particles or dyes dispersed in the drop fluid [e.g. (G2, G3, J2, L5, Ml, SI)]. A photograph of a fully circulating falling drop is shown in Fig. 3.5a. Since the internal flow pattern for the Hadamard-Rybczynski analysis satisfies the complete Navier-Stokes equation... 

Porous inkjet papers are in general created from colloidal dispersions. The eventual random packing of the colloid particles in the coated and dried film creates an open porous structure. It is this open structure that gives photographic-quality inkjet paper its apparently dr/ quality as it comes off the printer. Both the pore structure and pore wettability control the liquid invasion of the coated layer and therefore the final destination of dyes. Dispersion and stability of the colloidal system may require dispersant chemistries specific to the particle and solution composition. In many colloidal systems particle-particle interactions lead to flocculation which in turn leads to an increase in viscosity of the system. The viscosity directly influences the coating process, through the inverse relation between viscosity and maximum coating speed. 

Direct Black 38 (see also Benzidine-based dyes) Direct Blue 6 (see also Benzidine-based dyes) Direct Brown 95 (see also Benzidine-based dyes) Disperse Blue 1 Disperse Yellow 3... 

In order to demonstrate the feasibility of the LIDA concept in high density optical recording systems, a number of dyes have been investigated and the results reported (9,10). In this paper, the results for two of these dyes, Disperse Red II, and Disperse Blue 60 are described in detail. Disperse Red II is manufactured by ICI and Disperse Blue 60 is manufactured by Dupont. Both are derivatives of 1,4-diaminoanthraquinone. Their molecular structures are shown in Figure 2. 

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