Paper Dyes

The dyeing procedure for paper can be described basically by two processes the penetration of the dye molecule into the capillary spaces of the cellulose and then its adsorption on the surface of the fiber. The bonding forces are due to the effects charge (ionic bonds), precipitation, and intermolecular forces. 

Since unbleached cellulose and mechanical wood pulp have a distinctly negative charge due to the acid lignin groups, products of opposite polarity, i.e., basic or cationic, can interact with the fiber directly by ionic bonding. 

For the precipitation effects, acid dyes with little affinity to the fiber are rendered sparingly soluble (e.g., precipitated with alum) or are bound to the cellulose fiber with a polymer, generally a cationic fixative. 

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Dyeing accelerants Dyeing classes Dyeing of leather Dyeing paper Dyeing processes Dye initiators Dye-in-polymer systems Dye intermediates... 

Miscellaneous. The reaction products of sahcylaldehyde with certain compounds containing active methylene groups, eg, acetylacetone, are excellent uv absorbers. Films containing these compounds can be used as uv filters to protect light-sensitive foods, wood products, paper, dyes, fibers, and plastics (95). 

Direct Orange 15 (Cl 40003) [1325-35-5] (13), which is made by reducing the alkaline condensation product equivalent to Direct YeUow 11 with sulfide or formaldehyde, is an important paper dye used in dyeing brown paper for bags. 

Biphenyl, terphenyl, and their alkyl or hydrogenated derivatives generally serve markets where price and performance, rather than composition, is the customer s primary concern. Performance standards for heat-transfer appHcations are usually set by the fluid suppHer. The biphenyl—diphenyl oxide eutectic (26.5% biphenyl, 73.5% DPO) represents a special case. This composition has become a widely recogni2ed standard vapor-phase heat-transfer medium. It is sold throughout the world under various trademarks. In the United States, Dow (Dowtherm A) and Monsanto (Therminol VP-1) are the primary suppHers. Alkylated biphenyls and partially hydrogenated terphenyls serving the dielectric and carbonless copy paper dye solvent markets likewise are sold primarily on the basis of price and performance characteristics jointly agreed on by producer and user. 

J. A. Ulman and M. M. Cook, Sodium Borohydride Reductions—"Removal of Color and Metals Erom Paper Dyes," 204th National Meeting of the American Chemical Society, Washiagton, D.C., Aug. 23—28,1992. 

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Benzoazurine Paper. Dye soln-prepd by dissolving 2g of the product, supplied by Hartman-Leddon Co, in 1900ml of w and 100ml of glycerin Bluish-violet - Light violet Bleached... 

In spite of the reactive dyes with their outstanding wet-fastness, the direct dyes continue to hold a large share of the market for inexpensive cellulose and paper dyes. Apart from the new developments to replace the old established benzidine dyes, con-... 

Yellow paper dyes (e g., 30) are obtained by diazotization of these aromatic amines and coupling with acetoacetarylides [86],... 

Naphthols and Naphtholsulfonic Acids as Coupling Components. This series includes two important acid dyes with very similar structures C.I. Acid Red 88 (see Section 3.9.3), derived from diazotized naphthionic acid and 2-naphthol, and C.I. Acid Red 13, 16045 [2302-96-7] (2), from naphthionic acid and Schaffer s acid. Both are all-purpose dyes which, because of their attractive red shades, are still in use today in many areas of textile dyeing and also for leather and paper dyes. Wool dyeings produced with these dyes exhibit moderate fastness levels. 

To provide an overview chemical constitution and synthesis are combined in this section. The various application media for metal-complex dyes are a further ordering principle, which generates overlap of some sections with reactive dyes (Section 3.1), leather dyes (Section 5.1), and paper dyes (Section 5.3), demonstrating the typically complex interrelationship of constitution and application of dyes. 

Among metal-complex dyes only the planar 1 1 copper complexes exhibit sufficient substantivity to dye paper, whereas the octahedral 1 2 chromium and cobalt complexes are unsuitable for this purpose. Cationic substantive dyes, such as the bis-copper complex 26 [45] provide the most colorless effluent waters and superior fast paper dyeings that do not bleed out upon contact with milk, fruit juice, or alcohol [46],... 

Oxidation of dehydro tli i o-/ - to 1 u i dine su 1 fo nic acid with sodium hypochlorite [7] gives the yellow azo paper dye C.I. Direct Yellow 28, 19555 [8005-72-9] (10) without diazotization and coupling. 

The bridging of mono- or disazo compounds with a link capable of conjugation, such as phosgene, also leads to the substantivity necessary for paper dyes, e.g., C.I. Direct Ye How 51, 29030 [6420-29-7] (11). 

An important coupling component for paper dyes is 2-amino-5-naphthol-7-sulfonic acid (12) and its derivatives (R= H, acetyl, benzoyl, aryl, imidazoyl, thi-azolyl, triazolyl, etc.). 

For example, if 2-amino-5-naphthol-7-sulfonic acid is bridged with phosgene, highly substantive orange to red paper dyes such as C.I. Direct Orange 102, 29156 [i6598-63-6] (13) and C.I. Direct Red 239, [28706-25-4] (14) are formed with suitable diazo components. 

If suitable amino azo compounds are coupled to iV-phenylamino-5-naphthol-7-sulfonic acid, violet, moderately lightfast paper dyes with good brilliance are obtained, e.g., C.I. Direct Violet 51, 27855 [6227-10-7] (15). 

If amino azo compounds which contain 1-naphthylamine or 1-naphthylamine-6- or -7-sulfonic acid as their middle component are coupled with 2-amino-5-naphthol-7-sulfonic acid and their derivatives blue paper dyes such as C.I. Direct Blue 71, 34140 [4399-55-5] (16) are obtained, which have good lightfastness but generally a slightly dull shade. 

The cationic groups can also be introduced by other methods such as chloro-methylation and quatemization [13] or be converted by curing suitable hydroxymethyl compounds [14] with a pigment. In this way, for example, the lightfast cationic blue paper dye 28 can be obtained with C.I. Pigment Violet 23 51319 [6358-30-1]. 

Sulfur dyes are water-insoluble, macromolecular, colored compounds which are produced by bridging aromatic amines, phenols, and amino phenols with sulfur and/or sodium polysulfide [16], These dyes are of little interest for dyeing paper. Only C.I. Sulphur Black 1 (36), the most important dye of all in terms of volume, is used for special paper dyeings. 

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