Common Varieties Of Organic Pigments

Common varieties of organic pigments

First, azo pigments

 Water-insoluble organic compounds containing azo groups (-N = N-) in the molecular structure are among the most diverse and highest yielding organic pigments. Azo pigments are diazonium compounds obtained by diazotization of aromatic amines or heteroarylamines with acetylarylamine, 2-naphthol, pyrazolone, 2-hydroxy-3-naphthoic acid or 2-hydroxy -3-naphthoyl aromatic amine and other coupling components are coupled to form a water-insoluble precipitate, that is, a typical azo pigment. The synthesis method and azo dye is basically the same, but the latter is water-soluble. Typical azo pigments commonly used are orange, yellow and red pigments such as Permanent Orange RN (C.I. Pigment Orange 5), Aura Red (C.I. Pigment Red 21), Benzidine Yellow G (C.I. Pigment Yellow 12). In order to improve the properties of light-fast, heat-resistant and organic solvent-resistant pigments, two molecules can be condensed into macromolecules through aromatic diamine. The pigments thus prepared are known as macromolecular or condensed azo pigments such as Macromolecule Orange 4R (C.I. Pigment Orange 31), Macromolecule Red R (C.I. Pigment Red 166).

Second, Lake

 Water-soluble dyes (such as acid dyes, direct dyes, basic dyes, etc.) and the precipitating agent generated by the role of water-insoluble pigments. It is more brilliant shade, chromatography more complete, low production costs, higher than the original water-soluble dye fastness to light. Precipitants are mainly inorganic salts, acids, carriers and so on. Inorganic salt precipitation is the use of barium chloride, calcium chloride, manganese sulfate, etc. as a precipitating agent and water-soluble dyes to produce water insoluble barium, calcium, manganese and other salts such as: Permanent Red F5R (CI Pigment Red 48: 2), cedar red C (CI Pigment Red 53: 1). Acid precipitation is the use of phosphoric acid - molybdic acid, phosphoric acid - tungstic acid, tannic acid as a precipitating agent and water-soluble alkaline dye reaction of insoluble lakes such as: light rose lake (CI Pigment Violet 1) (CI Pigment Violet 3). Carrier precipitation is the deposition of water-soluble dyes on the carrier surface of aluminum hydroxide, barium sulfate and other carriers, the formation of water-insoluble lakes such as: acid golden lake (CI Pigment Orange 17), light lake lake (CI Pigment Blue 17) .

Third, phthalocyanine pigments

 The main body of the molecule is phthalocyanine, which are water-insoluble organic substances, mainly blue and green pigments. In 1934, the British Bu Nei Chemical Company and the German law firm respectively produced the first species ─ ─ phthalocyanine blue. Most products contain divalent metals, such as copper, nickel, iron, manganese, etc., but also the molecules of the benzene ring to pyrrole ring or other ring, the introduction of other molecules in the molecule, the different structures have different Performance and purpose. The main species in phthalocyanine pigments is copper-containing phthalocyanine blue (C.I. Pigment Blue 15). The main industrial production method is the phthalic anhydride and urea (also have direct use of phthalonitrile) in the presence of ammonium molybdate catalyst, and cuprous chloride reaction, the resulting crude commonly known as "copper phthalocyanine." Pigment post-processing methods are different, can be different products. Such as the crude dissolved in concentrated sulfuric acid, and then slowly precipitated in water, available alpha crystal, which is a reddish blue organic pigments; such as the crude dissolved in concentrated sulfuric acid, and then pass a small amount Chlorine, the molecule with 1 to 2 chlorine atoms, the resulting product than the chlorine shade of green; such as the crude and dried sodium chloride in a ball mill to obtain a stable green β crystal products . Crude in aluminum trichloride and sodium chloride melt heated to about 220 ° C, the introduction of chlorine, the introduction of molecular 14 ~ 16 chlorine atoms, the product obtained is bright green pigment; such as the introduction of a small amount of bromine , The resulting product is more yellow shade, more vivid.

Fourth, quinacridone pigment

 1958 by the United States DuPont started production. The production method comprises the following steps: self-condensation of diethyl succinate, condensing with aniline, ring closure, refining and oxidation to obtain a quinacridone pigment with γ crystal form. Because of its heat resistance, light resistance, brightness and other properties comparable with phthalocyanine pigments, it is called phthalocyanine red (C.I. Pigment Violet 19), in fact, the molecular structure of the two completely different. Such as the use of different conditions when oxidation, you get more blue shade of β crystal quinacridone pigment, the goods known as phthalocyanine violet.

 In addition to the above-mentioned varieties, there are some excellent varieties, such as bis-azine pigments, represented by the Permanent Purple RL (CI Pigment Violet 23); isoindolinone pigments, represented by the pigment yellow 2GLT (CI Pigment Yellow 109); benzimidazolone pigment represented by Permanent Orange HSL (CI Pigment Orange 36).

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