Organic Pigments 78 -3 78.3.1 Organic Blues 78.3.1.1 Copper Phthalocyanine Blue The major blue used within the coatings industry is copper phthalocyanine blue (PB 15), with its usage far outweighing other blues such as Indathrone blue (PB 60). Phthalocyanines are planar molecules with a tetrabenzotetraazoporphin structure as shown in Figure 78.1. Manufacture is comparatively easy despite the superficial complexity of the phthalocyanine mole- cule. Reaction of a phthalic acid derivative at temperatures approximating 190 ° C with a source of nitrogen such as urea and a metal or metal salt is usually all that is required to produce the appropriate metal phthalocyanine. Molybdate, vanadates, and certain compounds of titanium have been found to be useful catalysts for this condensation reaction. Figure 78.2 illustrates the chemistry behind the production of copper phthalocyanine blue. This condensation reaction results in the formation of copper phthalocyanine in a crude, nonpigmentary form. The product has thus to be finished or conditioned to give the pigment grade of choice. Typically crude phthalocyanine blue is characterized by a crystal size of the order of 50 µ m, a purity in excess of 92%, and a poor pigmentary strength. Metal-free phthalocyanine blue (PB 16) is normally manufactured via the sodium salt of phthalonitrile. Acid pasting is used to condition the crude and give the pigment. Copper phthalocyanine is commercially available in two crystal forms known as the α and β . The α form is described by the designations Pigment Blue 15, 15:1, and 15:2 and is a bright red-shade blue pigment. The β form is described as Pigment Blue 15:3 and 15:4 and is a bright green or peacock shade. The α form is meta-stable and requires special treatment to stabilize the crystal against its tendency to FIGURE 78.1 Structure of copper phthalocyanine blue (pigment blue 15). FIGURE 78.2 Chemistry of copper phthalocyanine. a Molybdate or vanadate. N NN N N N N N C C C CC C C C Cu O O O O NH NH NH O 4 NH NH O NH NH NH NH Urea Heat Copper Salt Catalyst a Heat Copper Complex N N N N N N NN C CC CC C CC Cu DK4036_book.fm Page 3 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 78 -4 Coatings Technology Handbook, Third Edition revert to the more stable, green-shade β crystal. If either of the unstable α crystal forms (PB 15 or 15:1) is used with strong solvents, conversion to the β form will occur upon storage of the system. Conversion from the α to the β form is usually accompanied by an increase in crystal size with subsequent loss of strength and shift to a greener hue. As stated earlier, copper phthalocyanine gives excellent service in most coatings applications, but there is considerable variation between both the chemical and crystal types available. Pigment Blue 15 is an α crystal with the reddest shade of the types commonly available. It is the least stable of the family and as such is often referred to as crystallizing red-shade (CRS) blue. This crystal form cannot be used in any solvent containing systems. Pigment Blue 15:1 is also an α crystal, but chemical modifications have been made to stabilize the structure against crystallization. Most commonly the molecule is chlorinated to the extent of introducing one chlorine molecule to give “monochlor” blue. Another technique involves the use of a substituted phthalocyanine, added to the pigment at levels approaching 10 to 15%, that confers crystal stability to the system. The monochlorinated grade is, as a consequence of the introduced chlorine atom, greener than the additive-stabilized crystal. Pigment Blue 15:2, described as “noncrystallizing nonflocculating” red-shade blue, is widely used within the coatings industry. The product is an α crystal that is stabilized against both crystallization and flocculation using additive technology. Pigment Blue 15:3 represents the green-shade, β crystal phthalocyanine blue and, as it exists in the stable crystal form, it is less susceptible to crystallization. Most commercial grades of Pigment Blue 15:3, however, contain from 4 to 8% of the α crystal, which will be adversely affected by strong solvent systems. A 100% β blue is too dull, opaque, and weak to be commercially attractive; hence, a proportion of the α crystal is left in the system, contributing considerably to the attractiveness of the system. Pigment Blue 15:4 represents a β blue that has been modified with phthalocyanine-based additives to give a green-shade blue that is resistant to flocculation and can be used in strong solvent systems. Copper phthalocyanine approximates the ideal pigment. It offers strength, brightness, economy, and all-around excellent fastness properties. Perhaps the pigment’s only disadvantages are its tendencies to change to a coarse, crystalline, nonpigmentary form in strong solvents and to flocculate or separate from white pigments when used in paints and lacquers. 78.3.1.2 Miscellaneous Blues Although the organic blues used in the coatings industry are primarily copper phthalocyanines, brief mention must be made of other blue pigments that find use in the coatings marketplace. Indanthrone blue, Pigment Blue 60, belongs to the class of pigments described as “vat pigments.” This pigment is expensive relative to copper phthalocyanine, and thus economic considerations are a limitation to its widespread use. Idanthrone blue is a very red-shade pigment with outstanding fastness properties. Carabazole violet, Pigment Violet 23, is a complex polynuclear pigment that is a very valuable red- shade blue of high tinctorial strength. The pigment possesses excellent fastness properties, and only its relatively high cost and its hard nature limit its more widespread use. From an economic standpoint it costs approximately three times as much as phthalocyanine blue. The pigment is used as a shading component in high performance coatings that call for particularly red-shade blue. 78.3.2 Organic Greens 78.3.2.1 Copper Phthalocyanine Green The major green pigment used as a self shade in the coatings industry is based on halogenated copper phthalocyanine and, as such, is termed phthalocyanine green. The Colour Index names are Pigment Green 7 and Pigment Green 36. DK4036_book.fm Page 4 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Organic Pigments 78 -5 Pigment Green 7, the blue-shade green, is based on chlorinated copper phthalocyanine with a chlorine content that varies from between 13 to 15 atoms per molecule. Pigment Green 36, the yellower shade, is based on a structure that involves the progressive replacement of chlorine on the phthalocyanine structure with bromine. The composition of Pigment Green 36 varies with respect to the total halogen content, chlorine plus bromine, and in the ratio of bromine to chlorine. Figure 78.3 illustrates the proposed structures of the phthalocyanine greens. In practice, no single pigment consists of a specific-molecular species; rather, each pigment is a complex mixture of closely related isomeric compounds. These pigments are ideal, since their tinctorial and fastness properties allow their use in the most severe application situations. They possess outstanding fastness to solvents, heat, light, and outdoor exposure. They can be used in masstone shades and tints down to the very palest of depths. Phthalocyanine greens are manufactured by a three-step process: crude phthalocyanine blue is first manufactured, then halogenated to give a crude copper phthalocyanine green, and finally conditioned to give the pigmentary product. 78.3.2.2 Miscellaneous Greens may find some minor application in the coatings industry. FIGURE 78.3 Structure of copper phthalocyanine greens. C CC C C C Cu Br Br Br Br Br Br Cl Cl Cl Cl Cl Cl NN CC NN NN N N C CC C C C Cu Br Br Br Br Br Br Br Cl ClCl Br Br NN CC NN NN N N Pigment Green 36 (Bluest shade also known as 3y) C C C C C C Cu Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl ClCl Cl Cl N N CC NN NN N N Pigment Green 7 Pigment Green 36 (yellowest shade also known as 6y) DK4036_book.fm Page 5 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Ta ble 78.2 gives a summary of the properties of some other commercially available organic greens that Organic Pigments 78 -7 FIGURE 78.4 Structure of azo-based oranges. NO 2 N N NNN C C CH N HO NO 2 O 2 N NN HO Cl SO 3 − NN HO Orthonitroaniline Orange PO 2 PO 5 PO 13 PO 16 PO 34 PO 38 PO 46 Dinitroaniline Orange N C COCH 3 CH 3 O Cl CH 3 Pyrazolone Orange 2 N NN NN C CH CH 3 H 3 C H 2 N O Cl 2 2 NH C O C O CNH O NNCH Dianisidine Orange Tolyl Orange Cl HO NHCOCH 3 Naphthol Orange H 5 C 2 Clarion Red Ba 2+ 2 DK4036_book.fm Page 7 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 78 -8 Coatings Technology Handbook, Third Edition latex-based paints and, with the exception of high bake enamels, in both architectural and industrial coatings. Pigment Orange 13 , Pyrazolone Orange, is synthesized by coupling tetrazotized 3,3-dichlorobenzidine onto 3-methyl-1-phenyl-pyrazol-5-one. The pigment is a bright, clean yellow-shade product that is tinctorially stronger than Pigment Orange 5. It may be recommended for interior coatings, particularly as a replacement for lead-based oranges. Pigment Orange 16 , Dianisidine Orange, is a diarylide orange that is prepared by coupling tetrazotized 3,3-dimethoxybenzidine onto acetoacetanilide. The pigment finds use in baking enamels, since its heatfastness is superior to that of other orange pigments with similar economics. Usage in interior coatings at full tone levels is also recommended. Pigment Orange 34 , To lyl Orange, is produced by coupling tetrazotized 3,3-dichlorobenzidine onto 3- methyl-1-(4-methyl-phenyl)-pyrazo-5-one. The pigment is a bright, reddish orange that offers moderate lightfastness and good alkali resistance, but poor solvent fastness. As such, the material is used in interior coatings applications, particularly where a lead-free formula is specified. Pigment Orange 38 , Naphthol Orange, is manufactured by coupling diazotized 3-amino-4-chloroben- zamide onto 4-acetamido-3-hydroxy-2-napthanilide. The pigment is a bright reddish orange that exhibits excellent alkali and acid fastness, moderate solvent fastness, and acceptable light- fastness when used at full tint. As such, the pigment finds use in baking enamels, latex, and masonry paints. Pigment Orange 46 , Clarion Red, is a metallized azo pigment manufactured by coupling diazotized 2- amino-5-chloro-4-ethylbenzene-sulfonic acid onto β -napthol and metallizing the product with barium to yield the pigment. The pigment has poor lightfastness, inferior alkali resistance, and inadequate solvent fastness, hence is not recommended for use in coatings. 78.3.3.2 Benzamidazolone-Derived Oranges The three benzimidazolone-derived oranges contain the azo chromophore and are all based on the 5- acetoacetylaminobenzimidazolone as the coupling component. Pigment Orange 36 is the product of coupling diazotized 4-chloro-2-nitroaniline to the benzimida- zolone. Pigment Orange 60 is the product of the coupling of 4-nitroaniline to the benzimidazolone. Because of the proprietary nature of this product, the structure of Pigment Orange 62 has not been fully declared (Figure 78.5 illustrates two typical structures): Pigment Orange 36 is a bright red-shade orange of very high tint strength. The opacified form of this pigment offers excellent fastness properties to both heat and solvents and a hue similar to the lead containing pigment, Molybdate Orange (PO 104). As such, Pigment Orange 36 finds major use in lead-free automotive and industrial high performance coatings. FIGURE 78.5 Structure of the benzimidazolone oranges. C C C C Cl N N H N H H N N NO 2 H 3 C PO 36 PO 60 O O O C C C C NO 2 N N H N H H N N H 3 C O O O Benzimidazolone Orange DK4036_book.fm Page 8 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Organic Pigments 78 -9 Pigment 60 is a transparent, yellow-shade orange that also exhibits excellent heat and solvent fastness with an exterior durability that allows the pigment to be used in high quality industrial and automotive finishes. Pigment Orange 62 is also a yellow-shade orange that shares the lightfastness properties of the other two oranges. Currently it is used in oil-based inks and artists’ colors. Its use in the coatings industry has yet to be fully explored. 78.3.3.3 Miscellaneous Oranges The structures of Pigment Orange 53, a pyranthrone, Pigment Orange 64, a heterocyclic hydroxy, and Pigment Orange 67, a pyrazoloquinazolone, have not been fully declared. Table 78.4 summarizes the properties of this class of pigments, which represents a series of oranges that are finding increased application in the coating industry. 78.3.4 Reds 78.3.4.1 Metallized Azo Reds Many of the reds used in the coatings industry fall into the chemical category of azo pigments because the azo chromophore —N=N— is a feature of the molecule. A further subdivision may be made into acid, monazo metallized pigments such as Manganese Red 2B (PR 48:4) and Calcium Lithol (PR 49:2) and nonmetallized azo reds such as the Naphthols (e.g. PR 17 and PR 23) and Toluidine Red (PR 3). Typically, each of the acid, monoazometallized pigments contains an anionic grouping such as a carboxylic (—COOH) or sulfonic acid (—SO 3 H) group, which will ionize and react with a metal cation such as calcium or manganese to form an insoluble, metallized pigment. Nonmetallized pigments do not contain an anionic group in their structure and, as such, will not complex with a metal cation. All azo reds contain one or more azo groups and are produced by similar reaction sequences. The initial reaction sequence, described as diazotization, involves reacting an aromatic primary amine with nitrous acid, formed in situ by reacting sodium nitrite with hydrochloric acid at low temperatures to yield a diazonium salt. Invariably the diazonium salt that is formed by this process is unstable and should be kept cold to avoid any decomposition. The diazonium salt is reacted quickly with the second half of the pigment, which is called the coupler. The coupling reaction takes place rapidly in the cold to yield the sodium salt of the pigment. This sodium salt is all but useless as a pigment for the coatings industry because of its marked tendency to bleed even TA BLE 78.4 Summary of the Properties of the Miscellaneous Oranges Colour Index Name Common Name/Description Properties PO 43 Perinone Red shade, strong, clean, vat pigment with excellent fastness properties; used in metallized finishes and high grade paints; shows slight solvent bleed PO 48 Quinacridone Gold Yellow shade; excellent lightfastness; lacks brightness in masstone; used in metallic finishes PO 49 Quinacridone Deep Gold Red shade; dull masstone; excellent durability; used in metallics PO 51 Pyranthrone Orange Medium shade; excellent fastness to solvent, light, and heat; dull in tin; exhibits slight solvent bleed; used in air dry and bake enamels PO 52 Pyranthrone Orange, red shade Vat pigment with excellent fastness to solvent, light, and heat; dull in tints; slight solvent bleed; used in air dry and bake enamels PO 61 Tetrachloroisoindolinone orange Medium shade; exhibits some solvent bleed; used in metallic automotive finishes PO 64 Bright shade red Excellent solvent and lightfastness; used in industrial coatings PO 67 Yellow shade Excellent brilliance in full shade; good gloss retention; very good weather- and lightfastness in full shade; used in industrial and automotive coatings DK4036_book.fm Page 9 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 78 -10 Coatings Technology Handbook, Third Edition in the weakest of solvent systems. The pigment is, therefore, metallized to confer improved properties on the product. The pigment suspension is then filtered and washed to remove any residual inorganics derived from the reaction. Figure 78.6 illustrates the structures of the different metallized azo reds that are readily available. The Lithol Reds are primarily Barium Lithol (PR 49:1) and Calcium Lithol (PR 49:2). Although limited in their application in the coating industry, these pigments do find some use at masstone levels — that is, the pigment is not tinted with a white tint base — where their fastness properties are acceptable. The pigments are bright reds with high tint strength and good dispersion characteristics. The barium salt is lighter and yellower in hue compared to the calcium salt. Permanent Red 2B is the generic name that encompasses Barium Red 2B (PR 48:1), Calcium Red 2B (PR 48:2), and Manganese Red 2B (PR 48:4). The major use of the calcium and barium salts is in baked industrial enamels, which are not required to be fast to outdoor exposure. Use in alkaline systems is severely restricted because of the poor alkaline fastness of these salts. FIGURE 78.6 Metallized azo reds. Lithol Rubine Add Cl CH 3 N HO COO − N SO 3 − CH 3 CH 3 N HO COO − N SO 3 − PR 57 PR 48 PR 52 Cl CH 3 N HO COO − N SO 3 − Cl PR 200 PR 53 PO 46 C 2 H 5 N HO COO − – COO − Subtract–COOH N SO 3 − Cl C 2 H 5 C 2 H 5 N HO N SO 3 − Cl CH 3 N HO N SO 3 − Cl C 2 H 5 Bon Red Exchange Positions CH 3 CH 3 Methylene (—CH 2 —) Addition Clarion Red Subtrat CH 2 Red Lake C Cl Red 2B DK4036_book.fm Page 10 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Organic Pigments 78 -11 The barium salt is characterized by a clean, yellow hue and, although slightly poorer than the bluer calcium salt in lightfastness and tinting strength, it does possess a slight advantage in bake stability. Manganese Red 2B has a sufficiently improved lightfastness to be used in implement finishes. The manganese salt is slightly bluer, dirtier, and less intense when compared to the calcium salt. Rubine Red also known as Calcium Lithol Rubine (PR 57:1) is a clean, blue-shade red pigment exhibiting the high tinting ability typical of the azo reds of this class. Its major use in coatings is in interior systems that call for an inexpensive red with good solvent and heat resistance. Again, to maintain maximum fastness properties, use of the pigment at near to masstone levels is recommended. BON red , used as calcium BON Red (PR 52:1) or Manganese BON Red (PR 52:2), is characterized by outstanding cleanliness, brightness, and purity of color. The manganese salt offers a very blue-shade red with improved lightfastness compared to the calcium salt. As such, this salt is suitable for exterior coatings applications. BON Maroon , (PR 63:1) is illustrated in Figure 78.7; the manganese salt of BON Maroon is of considerably more importance than either the calcium or barium salts. Its lightfastness is such that the pigment can be used at masstone levels for implement finishes. 78.3.4.2 Nonmetallized Azo Reds As implied by their classification, the nonmetallized azo reds do not contain a precipitating metal cation and, as such, offer increased stability against hydrolysis in strongly acidic or alkaline environments. Synthesis of this class of pigment follows the previously described classical method of diazotization of a primary aromatic amine followed by coupling of the resultant diazonium salt. No anionic groups capable of accepting a metal cation are present in the molecule; thus metallization is not a factor in their synthesis. Typical nonmetallized reds are Toluidine Red (PR 3) and the wide range of Napthol Reds as represented by Pigment Reds 17, 22, and 23. To l uidine Red is used in full shade in such coatings applications as farm implements, lawn and garden equipment, and bulletin paints, where a bright, economical red of adequate lightfastness is required. Because of the pigment’s poor durability in tint shades, it is rarely used at any level other than a full shade. The individual properties of the Napthol Reds depend on the specific composition of the product as well as the conditioning steps used during pigment manufacture. As a class, they are a group of pigments that exhibit good tinctorial properties combined with moderate fastness to heat, light, and solvents. Unlike the metallized azo reds, the Napthol Reds are extremely resistant to acid, alkali, and soap. These properties lead to their use in latex emulsion systems and masonry paint. In terms of performance and economic characteristics, the Napthols form a link between the toluidine reds at the lower end of the scale and the perylene and quinacridone reds at the higher end. 78.3.4.3 High Performance Reds Pigments for the exacting standards of today’s automotive coatings are required to show satisfactory durability to outdoor exposure in such states as Arizona and Florida for 2 and possibly 5 years before being approved for use in automotive finishes. Similar requirements are placed on pigments chosen for use in automotive repair systems and marine coatings. FIGURE 78.7 BON maroon. N HO COO − Ca 2+ N SO 3 − DK4036_book.fm Page 11 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 78 -12 Coatings Technology Handbook, Third Edition High performance reds fall into four basic classes: quinacridone reds and violets, reds based on vat dyestuffs known to include the perylene reds, reds derived from the benzimidazolone diazonium salts, and the disazo condensation reds. 78.3.4.3.1 Quinacridone Reds Quinacridones may be described as heterocyclic pigments in that their structure comprises a fused ring structure in which the ring atoms are dissimilar. In the case of quinacridones, the ring atoms are carbon and nitrogen (Figure 78.8). Addition of differing auxochromic groups such as methyl (—CH 3 ) and chlorine (—Cl) gives Pigment Red 122 and Pigment Red 202, respectively. The two most commercialized routes in the synthesis of quinacridone (PV 19) involve either the oxidation of dihydroquinacridone or the cyclization of 2,5-diarylaminoter-ephthalic acid as outlined in Figure 78.9. Subsequent conditioning leads to the desired crystal modification. Use of 2,5-diarylamino- FIGURE 78.8 Structure of translinear quinacridone. FIGURE 78.9 Routes to quinacridone. C N H N H O C O A. Cyclization of 2, 5-diarylaminoterephthalic Acid CH 2 COOC 2 H 5 CH 2 COOC 2 H 5 CH 2 COOC 2 H 5 CH 2 COOC 2 H 5 (i) cyclization (ii) + aniline (iii) oxidation NH NH COOC 2 H 5 COOC 2 H 5 C 2 H 5 OOC C 2 H 5 OOC Ring Closure in Polyphosporic Acid C N H N H O C C N H N H HH HH O C O O O O COOH HOOC N N oxidation trans linear quinacridone B. Oxidation of dihydroquinacridone DK4036_book.fm Page 12 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC [...]... © 20 06 by Taylor & Francis Group, LLC DK4036_book.fm Page 19 Monday, April 25 , 20 05 12: 18 PM 78-19 Organic Pigments PY 12 PY 81 NH C CH N N CH H3C PY 106 Cl PY 16 Cl COCH3 OCH3 Cl NH C CH N N 2 O COCH3 PY 55 CH3 H3C O PY 114 PY 126 PY 127 X Cl COCH3 Cl 2 O COCH3 PY 1 52 H5C2O NH C CH N N 2 2 NH C CH N N Cl O Cl COCH3 NH C CH N N Cl 2 COCH3 2 O PY 113 O PY 17 NH C CH N N CH3 NH C CH N N Y COCH3 2 O 2. .. Surface Specialties 79-1 © 20 06 by Taylor & Francis Group, LLC DK4036_book.fm Page 7 Monday, April 25 , 20 05 12: 18 PM Amino Resins 19 20 21 22 23 24 25 26 79-7 J W Holubka, P J Schmitz, and L -F Xu, J Coat Technol., Febuary, 77 (20 00) P J Schmitz, J W Holubka, and L -F Xu, J Coat Technol., May, 39 (20 00) G D Vaughn, J B Downie, and P E Ferrell, Paint & Coat Ind., August, 74 (20 01) B Pourdeyhimi, X Wang,... Monday, April 25 , 20 05 12: 18 PM 78-13 Organic Pigments TABLE 78.5 Types of Quinacridone Colour Index Name Hue Comments PO 48 PO 49 PR 122 PR 1 92 PR 20 2 PR 20 6 PR 20 7 PR 20 9 PV 19 Gold Deep Gold Magenta-yellow Red-yellow Magenta-blue Maroon Scarlet Yellow-shade red Violet-blue Red-yellow Maroon Quinacridone quinone Quinacridone quinone 2, 9-Dimethyl quinacridone Unsymmetrical monomethyl quinacridone 2, 9-Dichloroquinacridone... Yellow MX Yellow PY 14 OT Yellow (27 4–1744) Yellow NCG PY 16 PY 17 PY 106 PY 113 OA yellow (27 5–05 62) PT Yellow Yellow H10G Yellow HR (27 5–0570) (27 5–0050) Yellow GGR Yellow H10G PY 114 Yellow G3R PY 126 Yellow DGR PY 127 PY 1 52 Yellow GRL Yellow YR PY 55 PY 81 PY 83 a Comments Poor lightfastness; poor bleed resistance; major use in printing inks Redder shade than PY 12; improved heat stability and solvent... 78 .21 In spite of the apparent degree of complexity in the synthesis of such structures, these new high performance pigments continue to be introduced into the marketplace © 20 06 by Taylor & Francis Group, LLC DK4036_book.fm Page 20 Monday, April 25 , 20 05 12: 18 PM 78 -20 TABLE 78.6 Coatings Technology Handbook, Third Edition Summary of Diarylide Yellow Properties Colour Index Name Common Namea PY 12. .. Sandoz are Pigment Reds 24 2, 21 4, and 25 7 Pigment Red 24 2 is shown in Figure 78.15 The product is a yellow-shade red with a clean bright shade and very good all-around fastness properties It is recommended for lead-free coatings formulations for the production of high quality finishes and bright red shades CF3 CF3 Cl Cl N N N N OH Cl NH NH O FIGURE 78.15 Structure of Pigment Red 24 2 © 20 06 by Taylor & Francis... DK4036_book.fm Page 17 Monday, April 25 , 20 05 12: 18 PM 78-17 Organic Pigments Cl Cl Cl Cl N N N N Cl OH NH O HO NH O Cl FIGURE 78.16 Structure of Pigment Red 21 4 Cl Cl Cl Cl N N H O N H Ni H N H O N N Cl Cl Cl Cl FIGURE 78.17 Structure of Pigment Red 25 7 Pigment Red 21 4 (Figure 78.16) is a bluish red with properties similar to those of Pigment Red 24 2 Pigment Red 25 7 (Figure 78.17) is a nickel complex... J., 4, 100 (1999) J L Courter and E A Kamenetzky, Eur Coat J., 7–8, 24 (1999) M T Keck, R J Lewarchik, and J C Allman, U.S Patent 5 688 598, 1997 S Swarup and M A Mayo, U.S Patent 5 618 586, 1997 J D McGee and B D Bammel, Presented at the Eighth Annual ESD Advance Coatings Technology Conference, Detroit, MI, September 28 29 , 1998 27 I Hazan, Presented at the Eighth Annual ESD Advance Coatings Technology. .. pigments The thioindigo reds include Pigment Reds 36, 87, 88, 181, and 198 These pigments are noted for their © 20 06 by Taylor & Francis Group, LLC DK4036_book.fm Page 16 Monday, April 25 , 20 05 12: 18 PM 78-16 Coatings Technology Handbook, Third Edition OH CO NH R NH CO HO A N N N N A A R Cl Cl Red M.Wt 828 .5 Cl Cl Cl Red M.Wt 863 Cl Cl CH3 Cl Red M.Wt 803 FIGURE 78.14 Structures of the disazo condensation... 2, 9-Dichloroquinacridone Mixed solid solution 4,11-Dichloroquinacridone 3 ,10- Dichloroquinacridone β-Quinacridone γ-Quinacridone Mixed solid solution PV 42 terephthalic acid at the cyclization stage yields the unsubstituted trans linear quinacridone Use of 2, 5ditoluidinoterephthalic acid yields the 2, 9-dimethyl quinacridone, Pigment Red 122 As a group of high performance pigments, quinacridones find their primary . 5-diarylaminoterephthalic Acid CH 2 COOC 2 H 5 CH 2 COOC 2 H 5 CH 2 COOC 2 H 5 CH 2 COOC 2 H 5 (i) cyclization (ii) + aniline (iii) oxidation NH NH COOC 2 H 5 COOC 2 H 5 C 2 H 5 OOC C 2 H 5 OOC Ring Closure in. Orange 2 N NN NN C CH CH 3 H 3 C H 2 N O Cl 2 2 NH C O C O CNH O NNCH Dianisidine Orange Tolyl Orange Cl HO NHCOCH 3 Naphthol Orange H 5 C 2 Clarion Red Ba 2+ 2 DK4036_book.fm Page 7 Monday, April 25 , 20 05 12: 18 PM © 20 06. September 28 29 , 1998. 27 . I. Hazan, Presented at the Eighth Annual ESD Advance Coatings Technology Conference, Detroit, MI, September 28 29 , 1998. DK4036_book.fm Page 7 Monday, April 25 , 20 05 12: 18