Polyacrylonitriles basic dyes

Statistics for the production of basic dyes include those products hsted as cationic dyes, eg, cyanines, for dyeing polyacrylonitrile fibers and the classical triaryhnethane dyes, eg, malachite green, for coloring paper and other office apphcations (2,53). Moreover, statistics for triaryhnethane dyes are also hidden in the production figures for acid, solvent, mordant, and food dyes, and also organic pigments. Between 1975 and 1984, the aimual production of basic dyes in the United States varied from 5000—7700 t. However, from 1985—1990, aimual production of basic dyes varied from 5000—5700 t, and the annual sales value increased from 56 to 73 million per year. 

In the 1950s acid dyes were successively developed to dye nylon carpet with excellent fastness and uniform leveling. Development of polyacrylonitrile fiber stimulated the invention of anthraquinone basic dyes, modified disperse dyes in which quaternary ammonium groups are introduced. 

Basic Dyes. These are usuaUy the salts of organic bases where the colored portion of the molecule is the cation. They are therefore sometimes referred to as cationic dyes. They are appHed from mild acid, to induce solubUity, and appHed to fibers containing anionic groups. Thein main outiet is for dyeing fibers based on polyacrylonitrile (see Fibers, acrylic). 

Langmuir isotherms are typically found with ionic synthetic fibers and ionic dyes, eg, dyeing polyacrylonitrile with modified basic dyes, and on hydrophilic fibers in situations when the number of sites becomes very low. This may arise when the internal pH is such that only a small number of sites ionise. 

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. 

Cationic (Basic) Dyes. These water-soluble cationic dyes are applied to paper, polyacrylonitrile (e g. Dralon), modified nylons, and modified polyesters. Their original use was for silk, wool, and tannin-mordanted cotton when brightness of shade was more important than fastness to light and washing. Basic dyes are water-soluble and yield colored cations in solution. For this reason they are frequently referred to as cationic dyes. The principal chemical classes are diazahemi-cyanine, triarylmethane, cyanine, hemicyanine, thiazine, oxazine, and acridine. Some basic dyes show biological activity and are used in medicine as antiseptics. 

Basic (cationic) dyes. Basic dyes are water-soluble and produce colored cations in solution. They are mostly amino and substituted amino compounds soluble in acid and made insoluble by the solution being made basic. They become attached to the fibers by formation of salt linkages (ionic bonds) with anionic groups in the fiber. They are used to dye paper, polyacrylonitrile, modified nylons, and modified polyesters. In solvents other than water, they form writing and printing inks. The principal chemical classes are triaryl methane or xanthenes. Basic brown 1 is an example of a cationic dye that is readily protonated under the pH 2 to 5 conditions of dyeing [5]. 

Most of the basic dyes used for the polyacrylonitriles belong to the more recently developed azo and anthraquinone groups, as well as the methines. An example of an azo dye is ... 

Where W represents the wool molecule. Not much w ork has been done on the adsorption of basic dyes by animal fibres, but Glenz and Beckmann (Melliand Textilber., 1957, 38, pp. 296, 783, and 1152) have studied the exhaustion isotherms of basic dyes with polyacrylonitrile fibres. The curves which are obtained correspond with the Langmuir type of equilibrium, except that they are steeper in the initial stage. It is believed that this is because the dye cations are adsorbed extremely rapidly at the... 

The basic dyes are used primarily to color acrylic (polyacrylonitrile) fibers and polyester and nylon fibers when these fibers have been suitably modified to accept basic dyes. The dye-polymer bonding is ionic, so a relatively strong bond is formed. Basic dyes as a group are given an excellent rating in terms of wetfastness and fastness to rubbing. 

Basic dyes are water-soluble in the form of their salts and are used for colouring paper, leather, cellulose- and polyacrylonitrile fibres. The free bases dissolve in many organic solvents and find application similar to that of the solvent dyes. Basic dyes can function as pigments in lacquer form. Mixtures of basic dyes are usually responsible for brown, green and black tones. 

Basic dyes are triarylmethane, xanthene, azine, oxazine, thiazine and acridine derivatives. Azo and methine dyes are encountered particularly as colouring agents for polyacrylonitrile fibres. 

Loger et al. (24,25) chromatographed 19 basic dyes for polyacrylonitrile fibers on alumina with ethanol-water (5 2) and another 11 dyes on silica gel G with pyridine-water (1 2) as the solvent system. Arsov et al. (26) chromatographed 23 basic dyes on silica gel with various solvents. Takeshita et al. 

Thirteen dyes were separated by reversed phase TLC on C g modified silica gel using methanol-acetonitrile-aq. 5% Na2S04 (3 3 10) and then methanol-ethylmethyl ketone-aq. 5% Na2 SO4 (1 1 1) as mobile phases in same direction. Separation was optimum between pH 6.0 to 7.0 (145). Four basic dyes were separated on pretreated silica gel plates using HCIO4 or benzene sulphonic acid as counter ion and aqueous 50% or 60% ethanol as mobile phase (146). Polyacrylonitrile plates have been used for the separation of ten basic and common food dyes along with other dyes using diethylamine-anhy. acetic acid-H20 (4 1 15) as mobile phase (147). 

Uses Dye dispersant, antiprecipitant for polyamide, polyacrylonitrile fibers Features Prevents soiling of dyeing machines by basic dyes Properties Flakes Breviol DS [Cognis/Textiles ]... 

Highly colored, they have been used to dye cellulose acetate (552) and acrylic fibers (553). Cationic dyes prepared from 2-azothiazoles by simple alkylation on the ring nitrogen (552) have been used increasingly with the introduction of polyacrylonitrile fibers with basic sites that can be colored with such dyes (554). 

Azacarbocyanines. A cyanine containing three carbon atoms between heterocychc nuclei is called a carbocyanine (n = 1 in (46)). Replacing these carbon atoms by one, two, and three nitrogen atoms produces azacarbocyanines, diazacarbocyanines, and triazacarbocyanines, respectively. Dyes of these three classes are important yellow dyes for polyacrylonitrile, eg. Cl Basic Yellow 28 [52757-89-8J (Cl 48054) (47). 

Several high production products for the dyeing of polyacrylonitrile textile fibres come from the azacarbocyanines class. Example in this class are the azacarbocyanine Basic Yellow 11 (2.27), synthesised from 2,4-dimethoxyaniline (2.26) and Fischer s aldehyde (2.25) the diazacarbocyanine Cl Basic Yellow 28 (2.30), synthesised from the diazonium derivative of (2.29) and Fischer s base (2.28) as shown in Figure 2.16. These dyes, although they are very bright, do tend to suffer from low fasteess to light. 

Polyacrylonitrile. Polyacrylonitrile (PAN) hbres are often called by the shortened name of acrylic hbres. PAN is made by the polymerisation of acrylonitrile incorporating small amounts of co-reactants, which provide anionic centres, snch as sulfonic acid or carboxylic acid gronps. These ionic centres make it possible to dye PAN hbres with basic or cationic dyes, from an aqneons dyebath at pH 3.5-6.0, at temperatures above 80 °C. 

Enamine Dyes are obtained by condensation of heterocyclic methylene- a) -aldehydes with aromatic amines in an acid medium. Technically important dyes contain 1,3,3-trimethyl-2-methyleneindoline-a)-aldehyde as aldehyde component [7], C.I. Basic Yellow 11, the condensation product formed with 2,4-dimethoxyan-iline, is of particular importance (see 3.8.4). This compound dyes polyacrylonitrile a lightfast, brilliant, greenish-yellow shade. 

C.I. Basic Yellow21 is synthesized from 1,3,3-trimethyl-2-mcthylcneindoline-oo-aldehyde and 2-methyl-2,3-dihydroindoline. It dyes polyacrylonitrile in brilliant, greenish yellow shades and is very lightfast (see 3.8.4) ... 

The corresponding C.I. Basic Violet 16, 48013 6359-45-l, obtained from 4-dicthylaminobcnzaldehyde, dyes polyacrylonitrile a more intense bluish red... 

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