Organic Pigments In Coatings
Organic pigments have bright colors, strong tinting power, low density and non-toxicity, but the classic varieties are often less resistant to light, heat, solvents and migration than inorganic pigments. The advanced varieties of organic pigments can meet the requirements of long-term outdoor exposure, high-temperature processing, solvent resistance and migration resistance, which are comparable to inorganic pigments.
There are many varieties of organic pigments for coating, which can be divided into the following four categories according to their chemical structure.
Azo Pigments
Azo pigment refers to the organic pigment which contains azo group in its chemical structure. Azo pigment is the main variety of organic pigment, and its output accounts for about 60% of the total output of organic pigment. Azo pigment has a wide chromatographic distribution, with yellow, orange, red, brown, blue and other colors.
Phthalocyanine Pigment
The research and production of phthalocyanine pigment develops rapidly, so far there are more than 40 kinds of metal phthalocyanine and thousands of phthalocyanine compounds have been synthesized. Among the metal phthalocyanines, copper phthalocyanine occupies an important position in industrial production, followed by diamond phthalocyanine and nickel phthalocyanine. As coloring pigment, phthalocyanine pigment has the advantages of excellent performance, convenient manufacture and low price, so the output rises sharply. So far, phthalocyanine pigment has become one of the main categories of organic pigments.
Polycyclic Pigments
Polycyclic pigments include isoindolinone pigments, quinacridone pigments, carbazole dioxazine purple pigments, van system pigments, anthraquinone (derivatives) type reducing pigments and other types.
Their excellent light, weather and chemical resistance allows them to be used in lighter colored latex paints. Tetrachloroisoindolinone pigments, especially yellow pigments, are bright in color and have the pigment physical properties of light resistance, heat resistance, chemical resistance and other firmness that must be possessed by high-grade pigments, but at a higher price.
Aromatic methane pigments and other pigments
The basic dyestuffs of diphenyl, triphenylmethane and xanthene system, which have amino group and its inducer in the chemical structure, are divided into durable and non-durable types. Durable pigments have light resistance and superior chemical resistance, bright color and high tinting power, but are more expensive. Non-durable pigments have poor lightfastness and other properties and have been eliminated by many organic pigment manufacturers.