Ultramarine

Formerly derived from the natural mineral lapis lazuli, ultramarine blue pigments have, for more than a century, been manufactured synthetically. The materials used in the manufacture of ultramarines are china clay (a hydrated aluminosilicate), sodium carbonate, silica, sulfur and a carbonaceous reducing material such as coal tar pitch. For the manufacture of the blue pigments, the blend of ingredients is heated to a temperature of 750 800 °C over a period of 50-100 h, and the reaction 

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Ultramarine Pigments. Ultramarines are derived from lazurite [1302-85-8] (lapis lazuli), a semiprecious stone, which was the natural source of ultramarine blue for hundreds of years. Ultramarines can be prepared in many shades. Examples of commercially significant ones ate ultramarine blue, ultramarine violet, and ultramarine pink. The ultramarine pigment having a green shade can also be prepared but it is not commercially available. The first German patent issued in 1877 was for the manufacture of ultramarine red (42). 

Chemically, ultramarines are complex sodium aluminates having a zeoHte stmcture. Composition varies within certain wt % ranges, ie, Na20, 19—23 AI2O3, 23-29 Si02, 37-50 and S, 8-14. 

Ultramarine blues are prepared by a high temperature reaction of intimate mixtures of china clay, sodium carbonate, sulfur, siHca, sodium sulfate, and a carbonaceous reducing agent, eg, charcoal, pitch, or rosin. 

About 20,000 tons of ultramarines are produced worldwide. The largest manufacturers are Dainichi Seika (Japan), Nubiola (Spain), and Reckitts Colours International (RCI) based in Hull (U.K.), where Isaac Reckitt first began making laundry blue in the 1850s. HoUiday Chemical Hoi dings (HCH of Huddersfield, U.K.) purchased RCI in 1994 (43). 

Ultramarine pigments ate used in printing inks, textiles, mbber, artists colors, cosmetics, and laundry bluing. Because of their thermal stabiHty they are also used to color roofing granules. 

Examples of these framework siUcates include the feldspars, 2eohtes and ultramarines (see Clays Molecularsieves). 

Pigments and Glass. Tellurium has served as base for ultramarine-type cadmium sulfoteUuride (82) and cadmium teUuride pigments (83) (see Pigments, inorganic). In addition, smaU amounts of teUurium have been used in glass and ceramics to produce blue to brown colors (see Colorants for CERAMCS). 

The basic product of the ignition is Ultramarine Green. This is converted iato Ultramarine Blue by further heat treatment ia the preseace of sulfur, or iato Ultramarine Violet by heating with 5% ammonium chloride for four days at 200—250°C. Ultramarine Violet is converted into Ultramarine Red by treating it with gaseous hydrochloric acid at 70—200°C for four hours or by reaction with gaseous nitric acid at higher temperatures. 

Ultramarines ate iasoluble in water and organic solvents but soluble in acids, which cause their discoloration and the hberation of hydrogen sulfide. They have excellent permanency and resistance to alkaU but poor tinting and hiding power. 

Ultramarine Blue is used in salt iatended for animal feed (<0.5% w/w). AH ultramarines are used in the cosmetic field in such products as mascara, eyebrow pencils, and soaps. 

Because of the high processing temperatures there are few pigments suitable for use with PTFE. A number of inorganic pigments, particularly the cadmium compounds, iron oxides and ultramarines, may, however, be used. 

Chemical Designations - Synonyms Calcium Chromate (VI) Calcium Chromate Dihydrate Gelbin Yellow Ultramarine Steinbuhl Yellow Chemical Formula CaCr04-2H20. 

The structural complexity of the 3D framework aluminosilicates precludes a detailed treatment here, but many of the minerals are of paramount importance. The group includes the feldspars (which are the most abundant of all minerals, and comprise 60% of the earth s crust), the zeolites (which find major applications as molecular sieves, desiccants, ion exchangers and water softeners), and the ultramarines which, as their name implies, often have an intense blue colour. All are constructed from Si04 units in which each O atom is shared by 2 tetrahedra (as in the various forms of Si02 itself), but up to one-half of the Si... 

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