Acid dyes application

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. 

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... 

There is a wide diversity of chemical structures of anthraquinone colorants. Many anthraquinone dyes are found in nature, perhaps the best known being alizarin, 1,2-dihydroxyanthraquinone, the principal constituent of madder (see Chapter 1). These natural anthraquinone dyes are no longer of significant commercial importance. Many of the current commercial range of synthetic anthraquinone dyes are simply substituted derivatives of the anthraquinone system. For example, a number of the most important red and blue disperse dyes for application to polyester fibres are simple non-ionic anthraquinone molecules, containing substituents such as amino, hydroxy and methoxy, and a number of sul-fonated derivatives are commonly used as acid dyes for wool. 

The formation of complexes of the fluorescent tracer dye ammonium 1-phenyl-aminonaphthalene-8-sulphonate (10.41) with cyclodextrins has been investigated with favourable results, especially in environmental studies [33]. The ability of this dye to complex with cyclodextrins has been exploited mainly as an analytical tool in the study of cyclodextrin applications, since its fluorescence is easily measured. The interaction of a-, P-and y-cyclodextrins with azo acid dyes containing alkyl chains of different lengths has been reported [36,37]. The formation and isolation of solid complexes between P-cyclodextrin and Cl Acid Red 42, Cl Acid Blue 40 or Erionyl Bordeaux 5BLF (Ciba) have been reported [29]. 

In a study of ethoxylated ethylenediamine derivatives (12.4) in the application of acid dyes to nylon, covering a range of ethoxylation from 40 to 180 units per molecule (average... 

The use of liposomes as complexing agents in the application of premetallised acid dyes to wool has been investigated [21-24]. Liposomes are lipid structures containing aqueous compartments surrounded by bilayer membranes. However, the methods as yet available for the preparation of these agents are hardly practical in dyehouse terms (section 10.3.4). 

One of the first applications developed for flow cytometry was cell cycle analysis.2 There are numerous intercalating fluorescent DNA and RNA staining reagents that can be used to determine the amount of DNA in cells, an indicator of cell cycle stage and progression, as demonstrated in Figure 7.3. Nucleic acid dyes may be selective for DNA... 

Heavy metals are widely used as catalysts in the manufacture of anthraquinonoid dyes. Mercury is used when sulphonating anthraquinones and copper when reacting arylamines with bromoanthraquinones. Much effort has been devoted to minimising the trace metal content of such colorants and in effluents from dyemaking plants. Metal salts are used as reactants in dye synthesis, particularly in the ranges of premetallised acid, direct or reactive dyes, which usually contain copper, chromium, nickel or cobalt. These structures are described in detail in Chapter 5, where the implications in terms of environmental problems are also discussed. Certain basic dyes and stabilised azoic diazo components (Fast Salts) are marketed in the form of tetrachlorozincate complex salts. The environmental impact of the heavy metal salts used in dye application processes is dealt with in Volume 2. 

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 broad field of nucleic acid structure and dynamics has undergone remarkable development during the past decade. Especially in regard to dynamics, modem fluorescence methods have yielded some of the most important advances. This chapter concerns primarily the application of time-resolved fluorescence techniques to study the dynamics of nucleic acid/dye complexes, and the inferences regarding rotational mobilities, deformation potentials, and alternate structures of nucleic acids that follow from such experiments. Emphasis is mainly on the use of time-resolved fluorescence polarization anisotropy (FPA), although results obtained using other techniques are also noted. This chapter is devoted mainly to free DNAs and tRNAs, but DNAs in nucleosomes, chromatin, viruses, and sperm are also briefly discussed. 

The nomenclature given for these componnds is a nniversally recognised system for the naming of dyestuffs devised by the Society of Dyers and Colourists as part of their Colour Index (Cl). The Cl Generic Name is made up of the application class, the hne and a nnmber. Acid dyes are nsed on wool and polyamide, direct dyes on cel-lulosic fibres, paper and leather, disperse dyes on polyester fibres, reactive dyes on cellnlosic fibres and basic dyes on polyacrylonitrile and paper. 

The split into the various textile dyestuff application areas has, over recent years, seen a shift towards the two main outlets of disperse dyes for polyester and reactive dyes for cellulosics (mainly cotton), at the expense of directs and vat dyes for cotton, cationic dyes for acrylics and acid dyes for polyamide. The latter fibre has shown a comeback in recent years with the popularity of microfibres in sports and leisure wear. The position in 1998, with disperse dyes dominating in value terms, was as shown in Table 2.6. 

---