Lake pigments aluminum

A number of commercially available yellow monoazo pigment lakes are based on a pyrazolone sulfonic acid derivative as a coupling component. An example is the aluminum tartrazine lake, listed in the Colour Index as Pigment Yellow 100,... 

The major pigment of cochineal is polyhydroxyanthraquinone C-glycoside, car-minic acid (Formula 9.16), which may be present at up to 20% dry weight of the mature insects. Cochineal extract or carminic acid are rarely used as coloring materials for food, but are usually offered in the form of their lake. Aluminum complexes (lakes) can be prepared with ratios of cochineal and aluminum varying from 8 1 to 2 1, having corresponding shades from pale yellow to violet. 

Laevulose. See Fructose Lagorex CO 10X. See Cobalt octoate LAH. See Lithium aluminum hydride Lake black extra. See Solvent black 5 Lake bordeaux B. See D C Red No. 34 Lake red 4R. See Pigment red 3 Lake red C. See D C Red No. 8 D C Red No. 9 Lakewax 20. See Montan wax Lakewax 29, Lakewax 37. See Polyethylene, oxidized... 

The FD C certified colors are all water-soluble dyes, but can be transformed into insoluble pigments known as lakes by precipitating the dyes with alurninum, calcium, or magnesium salts on a substrate of aluminum hydroxide. The lakes are useful in appHcations that require color whereas in dry form, such as cake mixes, or where water may be present and bleeding is a problem, such as food packaging. FD C Red Lake No. 3 was deHsted in Febmary... 

Lakes are either dry toner pigments that are extended with a soHd diluent, or an organic pigment obtained by precipitation of a water-soluble dye, frequendy a sulfonic acid, by an inorganic cation or an inorganic substrate such as aluminum hydrate. 

Lake Red C is an example of a pigment that has been made insoluble by a heavy metal. In this case the metal is barium one barium ion precipitates two molecules. Other metals used are calcium, strontium, manganese, and aluminum. This pigment is used in polystyrene. 

Lake or pigment dyes form insoluble compounds with aluminum, barium, or chromium on molybdenum salts the precipitates are ground to form pigments used in paint and inks. 

Aluminum lakes of P.0.17 l are available in the USA. Properties which are pertinent to the coloristics and application of the pigment parallel those of the barium lakes. P.O,17 l, an equally high strength pigment, also affords brilliant shades and is used in packaging prints, especially for paraffin-based wrapping paper for bread. 

The pigment is then laked according to the procedure described for [3-naphthol pigments (Sec. 2.7.1.1). Aluminum lakes are an exception. A soluble aluminum salt is first converted to aluminum oxide hydrate, which is washed to remove salt. The moist product is then combined with the dye solution, while a more soluble aluminum salt is added simultaneously. The insoluble pigment is finally washed salt-free and dried. 

Apart from alizarin lake , which is now being formulated as an aluminum/cal-cium complex [3] (Sec. 3.6.2), the oldest known metal complex pigment is an iron complex. In 1885,0. Hoffmann reported on the iron complex of l-nitroso-2-naph-thol, which under the name of Pigmentgriin B (Pigment Green 8,10006) was first industrially exploited in 1921 by BASF. 

The aluminum lake is registered throughout the EC as E 132, in the USA as FD C Blue 2 as a colorant for foodstuffs and pharmaceuticals, provided certain purity conditions are met. Its shade is a bluish red. The pigment is somewhat sensitive to chemicals and to overcoating as well as to light. It is a tinctorially weak product. 

Lakes are insoluble forms of the dyes and are obtained by combining the color with aluminum or calcium hydroxide. The dyes provide color in solution, and the lakes serve as insoluble pigments. 

Colorants can be divided into water-soluble dyes and water-insoluble pigments. Some of the insoluble colors or pigments can also provide opacity to tablet coatings or gelatin shells, which can promote stability of light-sensitive active materials. Pigments such as the iron oxides, titanium dioxide, and some of the aluminum lakes are especially useful for this purpose. 

A hydroxypropyl methylcellulose film of pigment was exposed in a fadeometer for 3, 6, and 12 h. The rate at which the colorant degraded was noted from tint strength calculations and placed on a scale of 0-10, with the higher numbers indicating an increased tendency to fade. AL-aluminum lake. 

Aluminum oxide is used mainly in tablet formulations. It is used for decoloring powders and is particularly widely used in antibiotic formulations. It is also used in suppositories, pessaries, and urethral inserts. Hydrated aluminum oxide (see Section 18) is used in mordant dyeing to make lake pigments, in cosmetics, and therapeutically as an antacid. 

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