Pigments and Dyes

Colorants such as dyes or pigments usually used for inkjet ink compositions may be used in the ink. They may be used in addition to the other components of the inkjet ink or they can be within the monodisperse particles themselves. 

Anionic dyes are those dyes that, in aqueous solution, yield colored anions. Cationic dyes are those dyes that, in aqueous solution, yield colored cations. T Apically anionic dyes contain carboxylic or sulfonic acid groups as the ionic moiety. Cationic dyes usually contain quaternary nitrogen groups. 

Anionic dyes are selected from the group consisting of nitroso compounds, nitro compounds, azo compounds, stilbenes, triaryl-methane compounds, xanthene compounds, quinoline compoimds, thiazole compounds, azine compounds, oxazine compoimds, thi-azine compounds, aminoketone compounds, anthraquinone compounds, indigoid compounds and phthalocyanine compoimds. 

Cationic dyes include the basic dyes and some of the mordant dyes that are designed to bind acidic sites on a substrate, such as fibers. Useful t5q es of such dyes include the azo compounds, diphenylmethane compounds, triarylmethanes, xanthene compounds, acridine compounds, quinoline compounds, methine or polymethine compounds, thiazole compounds, indamine or in-dophenyl compounds, azine compounds, oxazine compounds, and thiazine compounds. 

An inkjet ink composition has been described which is formulated with a hyperhranched polymeric dye to give improved dye stability 

Heterocycles are very important plant pigments, for example porphyrins and anthocyanins (32.3 and 

bnt are also the basis of nnmerons synthetic pigments and dyes. Naturally derived dyes include substances snch as indigo (20.13.2), and synthetic pigments inclnde the very important copper phthalocya-nins (22.3), which are nsed for many pnrposes, inclnding in cyan inks. 

Other potential organic pigments are those that show metallic colours , such as the dithienyl pyrroles above, which form high melting ( 300 °C) golden lustrous crystals.  

This section refers to the effect of dyes and pigments on polymer systems and their colour fastness. Reviews have appeared on azo dye fading processes , disperse dye fading 2 and new trends in dye 

The liquid phase coating of rutile pigments with silica markedly suppressed the activity of the pigments 4 and the modelling of pigment discolouration has been undertaken . In polyethylene 

The cis-trans isomerisation process in the photofading of azo dyes has been found to be a first-order process in polypropylene and independent of polymer crystallinity l. oye lightfastness on leather has however been found to depend upon the colour of the dye lS while alkyl and peroxy radicals have been observed in the photofading of Rhodamine and azo dyes in solution . More specifically basic triphenylmethane dyes have been found to give benzophenone products on photofading 20 structure of a series 

Hoyle and J.F. Kinstle (Editors), Radiation Curing of Polymeric Materials , ACS Symposium Series 417, (1990). 

Allen (Editor), Photopolymerisation and Photoimaging Science and Technology , Elsevier Science Publishers Ltd., London, (1989). 

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Use of dimethylaminoethyl (also rert-butylaminoethyl) methacrylate as a monomer permits the introduction of pendent amino groups which can serve as sites for secondary cross-linking, provide a way to make the copolymer acid-soluble, and provide anchoring sites for dyes and pigments. 

H. A. hubs, ed.. The Chemistry of Synthetic Dyes and Pigments, American Chemical Society Monograph Series, Reinhold Publishing Corp., New York, 1955. 

H. Zollinger, Color Chemistry Syntheses, Properties and Applications of Organic Dyes and Pigments, VCH Pubhshers, New York, 1987. 

The GaAs laser used as light source emits at about 820 nm. Thus dyes in the actual sense are not needed rather, ir-absorbers for the spectmm between 750—850 nm Httie experience is available on this class of dyes, especially as far as their stabiHty is concerned, although much work has been done in this area. Also, infrared sensitive dyes and pigments, used in electrophotography, may be very suitable for WORM disks (8). 

The principal uses for 2-naphthalenol are in the dyes and pigments industries, eg, as a coupling component for azo dyes, and to make important intermediates, such as 3-hydroxy-2-naphthalenecarboxyhc acid (BON) (28) and its anilide (naphthol AS), 2-naphtholsulfonic acids, aminonaphtholsulfonic acids, and l-nitroso-2-naphthol/77/-5 /-5(/ (29). 

The dianhydride of 1,4,5,8-naphthalene tetracarboxyhc acid [81-30-1] has been of research interest for the preparation of high temperature polymers, ie, polyimides. The condensation of the dianhydride with o-phenylenediamines gives vat dyes and pigments of the benzimidazole type. 

Phosphoms trichloride is also used in the manufacture of antifoam agents, catalysts, dyes and pigments, as well as pharmaceutical and quaternary compounds, and is commonly used as a chlorinating agent. Phosphoms trichloride is used to make phosphoms oxychloride, which is used in the manufacture of adsorbents for air filters, antifoam agents, dyes and pigments, mineral-processing materials, pharmaceuticals (qv), and solvents. These uses represented 32,000 t of PCl in 1988 and 30,000 t in 1994. 

E. A. Clark and P. Anliker, ia O. Hutziager, ed.. Organic Dyes and Pigments, The Handbook ofEnvironmental Chemisty, Vol. 3, Part A, Sptinger-Verlag, Berlin, 1980. 

The major uses of aniline are in the manufacture of polymers, mbber, agricultural chemicals, dyes and pigments, pharmaceuticals, and photographic chemicals. Approximately 67% of the wodd production of aniline is used in the manufacture of rigid polyurethanes and reaction-injection-molded (RIM) parts for the constmction, automotive, and durable goods industries. 

In the dyestuff industry, anthraquinone still ranks high as an intermediate for the production of dyes and pigments having properties unattainable by any other class of dyes or pigments. Its cost is relatively high and will remain so because of the equipment and operations involved in its manufacture. As of May 1991, anthraquinone sold for 4.4/kg in ton quantities. In the United States and abroad, anthraquinone is manufactured by a few large chemical companies (62). At present, only two processes for its production come into consideration manufacture by the Friedel-Crafts reaction utilizing benzene, phthahc anhydride, and anhydrous aluminum chloride, and by the vapor-phase catalytic oxidation of anthracene the latter method is preferred. 

Dyes. Sodium nitrite is a convenient source of nitrous acid in the nitrosation and diatozation of aromatic amines. When primary aromatic amines react with nitrous acid, the intermediate diamine salts are produced which, on coupling to amines, phenols, naphthols, and other compounds, form the important azo dyes (qv). The color center of the dye or pigment is the -N=N- group and attached groups modify the color. Many dyes and pigments (qv) have been manufactured with shades of the entire color spectmm. 

Manufacture of Dyes and Pigments and pH Adjustment, Use of sulfamic acid in the manufacture of dyes and pigments involves removal of excess nitrite from diazotization reactions (see Azo DZ s) and is based on the following reaction ... 

J. E. Gwinn and D. C. Bomberger, Wastes from Manufacture of Dyes and Pigments, Vol. 5 Diphenylmethane and Triaylmethane Dyes and Pigments, Report No. EPA-600/2-84-111E, SRI International, Menlo Park, Calif., 1984. 

Monochlorobenzene. The largest use of monochlorobenzene in the United States is in the production of nitrochlorobenzenes, both ortho and para, which are separated and used as intermediates for mbber chemicals, antioxidants (qv), dye and pigment intermediates, agriculture products, and pharmaceuticals (Table 5). Since the mid-1980s, there have been substantial exports of both o-nitrochlorobenzene, estimated at 7.7 million kg to Europe and -nitrochlorobenzene, estimated at 9.5 million kg to the Far East. Solvent use of monochlorobenzene accounted for about 28% of the U.S. consumption. This appHcation involves solvents for herbicide production and the solvent for diphenylmethane diisocyanate manufacture and other chemical intermediates. 

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