Colorants in inks

HP has developed, in partnership with International Paper, what they call Paper Enhancement Technology. This development, practically, uses a T)i-component" ink approach by introducing a "fixer" on top of the paper to react with the colorant in ink, fix it and keep it near the paper surface. This approach enables uniform optical density of the ink as well as well-defined ink dots, faster drying time and high optical densities, aU done at low paper cost. HP Paper Enhancement Technology is described in Fig. 11. 

Amorphous forms of carbon have many uses. These include the black color in inks, pigments (paints), rubber tires, and dry cells. 

Bae, J., 2007. Color in ink-jet printing influence of structural and optical characteristics of textiles (Doctoral thesis). North Carolina State University, Raleigh, NC. 

The salts have been used for centuries to produce brilliant and permanent blue colors in porcelain, glass, pottery, tiles, and enamels. It is the principal ingredient in Sevre s and Thenard s blue. A solution of the chloride is used as a sympathetic ink. Cobalt carefully used in the form of the chloride, sulfate, acetate, or nitrate has been found effective in correcting a certain mineral deficiency disease in animals. 

White Pigments. Opaque white pigments commonly used in inks, in order of decreasing opacity, ate titanium dioxide and zinc oxide. TiO is by fat the most popular white pigment. Mixtures of whites ate often made with the various colored pigments to add opacity or to make pastel colors. 

Transparent white pigments (extenders) commonly used in inks, in order of decreasing transparency, ate alumina hydrate, magnesium carbonate, calcium carbonate, blanc fixe (precipitated barium sulfate), talc, and clay. Extenders ate sometimes used to reduce the color strength and change the theology of inks. 

The inks formulated for jet printing must be very fluid, stable, and free of any particles that could cause clogging of the jet nozzles, and be capable of depositing and adhering to a substrate with a minimum of character fogging. They are generally formulated with soluble dye colorants in a suitable aqueous or solvent-based vehicle (9). 

A smaller volume use of PAP is the production of dyestuffs and resins. Nigrosine dyes are widely used as black colorants in plastics, inks (qv), textiles, and shoe poHshes. 

ASTM E20-843 for color strength in ink, and ISO 8781 (parts 1—3) for evaluating tinting strength, fineness of grind, and gloss. 

Cobalt as a Colorant in Ceramics, Glasses, and Paints. Cobalt(II) ion displays a variety of colors in soHd form or solution ranging from pinks and reds to blues or greens. It has been used for hundreds of years to impart color to glasses and ceramics (qv) or as a pigment in paints and inks (see CoLORANTS FOR CERAMICS). The pink or red colors are generally associated with cobalt(II) ion in an octahedral environment and the chromophore is typically Co—O. The tetrahedral cobalt ion, Co—chromophore, is sometimes green, but usually blue in color. 

Red 2G (E 128, Cl Food Red 10, Azogeranine) is a mono azo dye, 8-acetamido-l-hydroxy-2-phenylazo-3,6-naphthalenedisulfonate. The calcium and potassium salts are also permitted. Red 2G is a red powder or granules, soluble in water, sparingly soluble in ethanol. The absorption maximum is 532 nm in water, E, " = 620. It is not permitted as food colorant in the US. It can be used as a dye for inks, paper, fabrics, and histology stains. " ... 

Elderberries yield a violet color. In times past, not only were the berries used to color hair and wine, but also to enliven fabric and basket materials. Elder-berries have also been used to make beautifully colored inks and to tint paper blue. With alum used as a mordant to fix the dye, the berries give a purple color, used best on wool and silk. Elderberries mixed with alum and salt produce a lilac hue, and mixed with alum and cream of tartar they make a lovely crimson shade. Chrome used as a mordant with elder-berries produces a blue dye and tin used as a mordant produces blue gray. 

Whether for a class demonstration, a practical joke, or perhaps a clandestine activity, disappearing ink is a fascinating substance. What is the secret to its action One formulation of disappearing ink contains a common acid-base indicator, that is, a substance that by its color shows the acid or basic nature of a solution. One acid-base indicator that shifts from a colorless hue under acidic conditions to a deep blue color in alkaline solutions is thymolphthalein. If the indicator starts off in a basic solution, perhaps containing sodium hydroxide, the typical blue color of an ink is perceived. How does the ink color disappear This behavior is dependent upon the contact of the ink with air. Over time, carbon dioxide in the air combines with the sodium hydroxide in the ink solution to form a less basic substance, sodium carbonate. The carbon dioxide also combines with water in the ink to form carbonic acid. The indicator solution responds to the production of acid and returns to its colorless acid form. A white residue (sodium carbonate) remains as the ink dries. 

The pigment industry produces primarily the more transparent diarylide yellow pigment types. This has its advantages, particularly in the field of printing inks, since yellow is printed as the last color in three or four color printing (Sec. 1.8.1.1). Highly transparent varieties are almost exclusively resinated and are often easy to disperse. 

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