Ultramarine pigment

Ultramarine pigments are sodium aluminum silicates with the composition Nag[Al5Si5024] Sx (Na-rich) or Nag y[Al6.ySif +y024] Sx (Si-rich), which can have a blue, green, red or violet tone, depending upon the composition of the chromogenic Sx-group. 

The multistage manufacture of ultramarine pigments begins with careful partial calcination of the mineral kaolinite (china clay) to metakaolinite  

Ultramarine pigments blue, green, red, violet tones 

A wide mesh three-dimensional zeolite structure is built up out of metakaolinite and the other raw materials (Na2S03, S, reducing agent) in a very complex firing process in a reducing atmosphere (SO2)  

The reaction with the intermediately formed Na2Sx yields white prae-ultramarine  

In the 21st adaption to EEC Council Directive 67/548, the lead chromate pigments C.I. Pigment Yellow 34 and C.I. Pigment Red 104 have been added individually [3.160]. These pigments are classified in the same manner as lead chromate and must be labelled with a skull and crossbone (T) and the above mentioned risk (R) and safety phrases (S). 

With respect to improved protection of public health, special restrictions on can-cerogenic and teratogenic substances and their corresponding preparations have been established by the 14th amendment of EEC Council Directive EEC 76/769 

In accordance with the 14th amendment of EEC Council Directive EEC 76/769 

Lead containing coatings and paints with a total lead content exceeding 0.15 % of the total weight of the preparation must carry the phrase Contains lead. Should not be used on surfaces liable to be chewed or sucked by children in accordance with EEC Council Directive 89/178 [3.164] and German GefStoffV [3.158]. 

The result of the competition is shrouded in controversy, but the common view is that Guimet in France and Gmelin in Germany independently devised similar processes for synthetic preparation in 1828 [3.153]. The prize was awarded to Guimet and he is frequently referred to as the first person to produce ultramarine blue on a commercial scale. 

Synthetic ultramarines are inorganic powder pigments, commercially available in three colors  

The proportions of the chemical constituents can vary, but the typical lattice repeat unit of a blue ultramarine is Na. 9AI5 Si(5.4O24S4 2. The violet and pink variants differ from the blue mainly in the oxidation state of the sulfur groups. This is reflected in somewhat lower sodium and sulfur contents. 

In the simplest ultramarine structure, equal numbers of silicon and aluminum ions are present and the basic lattice unitisNa6Al6Si6024 or (Na )6(AP )6(Si )6(0 )24 with a net ionic charge of zero as required for structural stability. 

The nature of the sulfur groups responsible for the color and their incorporation into the sodalite structure is reviewed in Refs. [3.158-3.162]. There are two types of 

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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). 

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. 

Obviously, in solution, 83 is not stable against oxidation. It is stable in the mineral lapis lazuli, and the industrial ultramarine blue pigment [28]. In these materials, the radical 83 is encapsulated in the -cages of the sodalite structure, which protects it against oxidation. In ultramarine pigments, another radical anion polysulfide, 82 , has been observed. 

It is supposed to originate from the dissociation of 84 . This dissociation is perhaps significant at high temperatures, like those of the synthesis of ultramarine pigments or those of doping of alkali halide crystals. 83 and 82 radicals have also been observed in the alkali halides doped with sulfur [30, 31]. Another radical anion polysulfide, 84 , has been identified, by EPR experiments, in solution in DMF, originating from the dissociation of 8g , which is the least reduced polysulfide in this solvent [32]. 

Ultramarine pigments ultramarine green, blue, violet, and red ... 

Oil absorption also varies with particle size (usually 30-40 g%). The pH lies between 6 and 9. Ultramarine pigments are largely odorless, nonflammable, and do not support combustion. 

A good ultramarine pigment would meet the following specification ... 

The stability and safety of ultramarine pigments are the basis of their wide range of applications which include the following ... 

Paints. Ultramarine pigments are used in decorative paints, stoving finishes, transparent lacquers, industrial paints, and powder coatings. They are not recommended for colored, air-drying paints for outdoor use in urban atmospheres. 

Paper and Paper Coatings. Ultramarine pigments are used to enhance the hue of white paper or for colored paper. They can be added directly to the paper pulp, or used in applied coatings. When added to the pulp, acid-resistant grades must be used if acid-sizing is employed. They are particularly suitable for colored paper for children s use. 

Detergents. Ultramarine pigments are widely used to enhance the effects of optical brightening agents in improving whiteness of laundered fabrics [3.176], They do not stain or build up with repeated use. 

Cosmetics and Soaps. Ultramarine pigments are widely used in cosmetics. Pink is not recommended for toilet soaps because of the color shift to violet. Advantages are complete safety, nonstaining, and conformance to all major regulations. 

Toys and other Articles/Materials for Children s Use. Ultramarine pigments are widely used in plastics and surface coatings for toys, children s paints and finger paints, modeling compositions, colored paper, crayons, etc. They comply with major regulations and standards. 

There are only four major producers of high-grade ultramarine pigments -Dainichi Seika (Japan), Nubiola (Spain), Prayon (Belgium) and Reckitt s Colours (France, United Kingdom) - with two smaller producers in Austria and Colombia. In 1990 total worldwide production was ca. 20000 t/a. 

Ultramarine Pigments. Ultramarines are derived from lazurite (Lapis Lazuli), a semiprecious stone they can be prepared in many shades,... 

Ultramarine Blues, Violets, and Pinks. Ultramarine pigments are noted for their rich colors, moderate heat stability, chemical resistance, bleed resistance, opacity, weatherability, and attractive economics. They are known to be sensitive to an acidic environment, which may have some effect on their utility. Ultramarine pigments are some of the very old and venerated colorants since they were originally naturally occurring materials, mainly in Middle Eastern countries. Sodium is a constituent of ultramarine pigments, which makes it unique as sodium does not usually appear as a component of color pigments. 

In outdoor weathering, reactions of moisture are just as important as the direct interaction with light. Ultramarine pigments can react in typical acid rain conditions... 

Colored pigments the optical effect is caused by selective light absorption and also to a large extent by selective light scattering (examples iron oxide red and yellow, cadmium pigments, ultramarine pigments, chrome yellow, cobalt blue)... 

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