Dyestuffs disperse dyes

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. 

Dyestuffs. The use of thiophene-based dyestuffs has been largely the result of the access of 2-amino-3-substituted thiophenes via new cycHzation chemistry techniques (61). Intermediates of type (8) are available from development of this work. Such intermediates act as the azo-component and, when coupled with pyrazolones, aminopyrazoles, phenols, 2,6-dihydropyridines, etc, have produced numerous monoazo disperse dyes. These dyes impart yeUow—green, red—green, or violet—green colorations to synthetic fibers, with exceUent fastness to light as weU as to wet- and dry-heat treatments (62-64). 

Commercial Disperse Azo Dyes. The first proposal to use insoluble dyes in suspension in an aqueous foam bath, ie, disperse dyes, to dye cellulose acetate was in 1921 (60). Commercialization of disperse dyes began in 1924 with the introduction of the Duranol dyes by British Dyestuffs Corporation (61) and the SRA dyes by British Celanese Company (62). In contrast to the acid monoazo dyes, derivatives of benzene rather than of naphthalene are of the greatest importance as coupling components. Among these components mono- and dialkylariifines (especially A/-P-hydroxyethyl-and A/-(3-acetoxyethylanifine derivatives) are widely used couplers. Nitrodiazobenzenes are widely used as diazo components. A typical example is CeUiton Scarlet B [2872-52-8] (91) (Cl Disperse Red 1 Cl 11110). 

The appearance of synthetic fibers in the 1920s accelerated the further development of anthraquinone dyes. Soon after British Celanese succeeded in commerciali2ing cellulose acetate fiber in 1921, anthraquinone disperse dyes for this fiber were invented by Stepherdson (British Dyestuffs Corp.) and Celatenes (Scottish Dyes) independendy. Anthraquinone disperse dyes for polyester fiber were developed after the introduction of this fiber by ICI and Du Pont in 1952. These dyes were improved products of the disperse dyes that had been developed for cellulose acetate fiber 30 years before. 

Thermal Fixation Properties of Disperse Dyes on Polyester—Gotton. This method assesses the fixation properties of disperse dyes as a function of the time, temperature, dyestuff concentration, or presence and amount of auxiUary agents. The polyester—cotton fabric is padded and dried, the cotton dissolved in sulfuric acid and washed out of the blend, and the amount of dye on the polyester component assessed by either reflectance or measuring the optical density of a solution of dye obtained by extracting the dye with boiling chloroben2ene solvent. 

The different classes of compounds that have been successfully separated by MEKC include, among others, phenols [932,933], antioxidants [930,934], vitamins [935], phthalate esters [931,936] (Figure 4.26) and charged and neutral dyestuffs, including some dispersive dyes [937-939]. The separation of various priority... 

Thermosol dyeing. The characteristics of low-molecular-weight polyester dyes can be utilized in thermosol dyeing processes. In this continuous dyeing process the material is impregnated with the dispersed dye, dried, and heated to a temperature of approximately 200-210°C. The dyestuff is fixed by sublimation into the fiber. 

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. 

The largest usage is in polyester and many dyestuff companies have disperse dye ranges for this purpose, some of which are also applied to polyamide fibres. The main colours are in the yellow, orange, red, pink and violet areas with coumarins, methines and perylene dominating the structural classes. 

A special compatibilzer for anionic/cationic dyeing systems. Dispersing and leveling agent for disperse dyes. Excellent after scour prevents cross staining of dyestuffs in multifiber dyeing. 

Excellent scouring agent for removal of loose dyestuff good dye dispersing properties—anionic. 

Cellulose acetate yarn, when it appeared on the market in 1921, presented a new problem because it had no adequate affinity for any of the existing dyestuffs. The first satisfactory method of coloration was due to Holland Ellis who observed that many simple insoluble azo dyes would be absorbed by cellulose acetate from an aqueous dispersion, stabilized with sulphated fatty alcohols or similar surface active compounds. A large number of dyes whose application depends on this principle have now made their appearance and are known as the disperse dyes. The demand for this group has increased very significantly with the advent of the truly synthetic man-made fibres. 

The choice, until recently, has been between a disperse dye with wetfastness which is not all that could be desired, accompanied by coverage of yarn variations, and faster colours which show up differences in physical and chemical properties of the polymer. When, in 1959, I.C.I. placed the Procinyl dyes on the market an advance of considerable importance was made. They are reactive dyes based on disperse dyestuff molecules containing chlorotriazinyl groups. Under neutral conditions the pattern of behaviour is that of a disperse dye and yarn irregularities are covered up to a great extent. When alkali is added to the dyebath, fixation takes place, giving wet-fastness of a high order. 

The exhaustion of disperse dyes, at equilibrium, is quite good, but the diffusion into the fibre is extremely slow. I he time required to reach equilibrium, therefore, is much longer than would be permissible in practice. By selecting disperse dyes with the most rapid rates of diffusion it is possible to dye pale to medium shades at the boil within a reasonable time. Dyestuffs which are suitable are shown below- and it will be observed that they all possess simple molecular structure. 

This is not easy because the disperse dyes will always be adsorbed more heavily by the polyamide. There are a few disperse dyes which give a reasonably solid colour w hen a carrier is used. The tendency is for the polyamide to dye a heavier shade at the commencement, and for the dyestuff to become transferred to the other fibre on prolonged boiling. 

Hartonyl. [Hart Chem. Ltd.] Ethoxy-lated fatty amine leveling aid, dispersant, dyeing assistant antiprecipitant for dyestuffs, textile applies. 

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