Metal commercially available pigment

The azo group (—N=N—) may be replaced by the analogous (—CH=N—) moiety to form an azomethine complex pigment, usually with copper as a chelating metal. The number of commercially available products in this group is also restricted. They typically afford yellow shades. Those species that provide the required lightfastness and weather resistance are used in automotive finishes and other industrial coatings. 

Commercially available P.O.46 types are usually quite transparent. They are employed primarily in packaging printing inks, also in offset and metal deco printing. Publication gravure inks, plastics, especially PVC, LDPE, and elastomers, as well as general industrial paints are suitable media for pigment application. P.O.46 is less solvent resistant than P.R.53 1, but it is faster to alkali and acid. In terms of lightfastness, P.O.46 performs poorly 1/3 and 1/25 SD prints equal only step 1 on the Blue Scale. 

Commercially available azo and azomethine metal complex pigments cover the spectral range from considerably greenish to reddish yellow and yellowish orange. Compared to their parent structures (the corresponding azo and azomethine compounds), azomethine metal complexes frequently exhibit a distinctly duller shade. Formation of the metal complex often shifts the color of an originally yellow material in the greenish yellow direction. 

Recent developments in this class prefer azomethine complexes as chemical structures rather than azo metal complexes. The list of commercially available types includes Pigment Green 8 and 10, Pigment Yellow 117,129,150,153,177,179, and Pigment Orange 59,65, and 68, as well as P.R.257. 

P.R.206 is a mixed crystal type and consists of unsubstituted quinacridone and quinacridone quinone. The ratio between the two components as well as the crystal modification is not yet known. P.R.206 affords a very dull, yellowish shade of red, referred to as maroon. The pigment is considerably weaker than perylene pigments. All commercially available types of P.R.206 are more or less transparent and are used mostly in metallic finishes for automobiles, to which they lend reddish shades of copper. The pigment is often found to be difficult to disperse. The finishes frequently exhibit rheological problems, especially at high pigment concentration. 

Metallic Pigments. These pigments are metal flakes of various sizes made up of aluminum, copper, zinc, and/or their alloys. The aluminum flakes develop the silver metallic colors, whereas the copper, zinc, and aluminum alloys produce the gold, copper, brass, and bronze colors. The metal effect is modified, not only by shape and size, but also by perticle size distribution within a given product. Since aluminum, in particular, as a fine dry powder, can form explosive mixtures with air, most of these materials are commercially available in paste or liquid concentrates. In addition, surface treatments of these materials enhance their appearance and performance. Flakes of other metals, such as stainless steel, are used for surface protection purposes such as corrosion resistance and electrical conductivity. 

Metallic pigments reflect infrared radiation and hence are able to reduce the heat emission from a surface coated therewith, according to Kirchhoff s law 1-/J(A.) = e(X,), where R = reflectance and e = emissivity. Hybrid polymers are superior to commercially available binders, considering both miscibility with IR-reflective pigments and the achievable degree of filling. However, in order not to affect the optical function of the pigments, the infrared absorption of the binder should also be as... 

P.R.66, a barium salt, is sold only in the USA. The pigment is also available as an aluminum oxide hydrate precipitate. Its shade is considered a brilliant medium red, which is somewhat yellower than that of the chemically related P.R.67. Commercial types of P.R.66 are very transparent. The pigment is highly sensitive to acid, alkali, and soap. Its fastness to organic solvents is poor, its fastness to overcoating as well. P.R.66 exhibits limited lightfastness. Its main application is in metal deco printing. 

It was not until the nineteenth century that artists began to purchase ready-made commercial paints. Today paint colors have standardized specifications. Regardless of type, paint still consists of pigment and binder, as it has for centuries. Many colors originally produced from natural pigments are now made synthetically. The metal paint tube was developed in 1841. Paints that for centuries had been mixed and stored by the artist in various ways in the studio were suddenly available in an easily portable container. Artists who had found it difficult to paint on location were able to create many masterpieces outdoors, on location, as a result of tube paint becoming available. 

The best source for Chi a is the cyanobacterium Spirulina platensis, which is available commercially. Chi a/b mixtures can be obtained from all green plants. All other Chls are less readily accessible, which limits their applications. Several Chi derivatives are used as dyes for food colorants (Cu-chlorophyllin) and cosmetics. The chlorophyll used for the latter is a complex mixture of degradation products. More recently, (B)Chl derivatives have gained increasing interest as photosensitizers in photodynamic therapy of cancer, these compounds include pigments in which the isocyclic ring is opened and/or the central metal has been removed or replaced (e.g., by Pd" " ) to increase phototoxcicity (12, 13). 

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