Phthalocyanine pigments types

Knowledge of the most important types of copper phthalocyanine pigments is useful for the understanding of the processes concepts underlying pigment manufacture. Heading the list are the a- and [i-modil i cations of unsubstituted Copper Phthalocyanine Blue (Sec. 3.1.2.3). The a-modification exhibits an unstabilized and a stabilized form as to change of crystal modification. 

Copper phthalocyanine pigments also demonstrate good overall stability to organic solvents. A number of solvents, however, especially aromatics, may cause a change of modification in unstable types or overcrystallization in stable varieties. This phenomenon is largely due to the tendency of the stable phase to nucleate. The particle size of the resulting cystals decreases as the number of nuclei rises. (3-Copper Phthalocyanine Blue is the thermodynamically stable modification. 

The a- and (i-types of Copper Phthalocyanine Blue reign supreme among commercially available phthalocyanine pigments. There is also an increasing amount of interest in the phase-stabilized form of the a-crystal modification. Both modifications are also supplied as flocculation resistant types. 

Table 27 lists the types of phthalocyanine pigments which are currently supplied. 

Incorporated in plasticized PVC, P.B.15, like other phthalocyanine pigments, is usually entirely fast to migration. Moreover, it provides excellent lightfastness. P.B.15 also finds use in various types of PUR foam materials as well as in rubber. Its redder and frequently cleaner shade compared to corresponding stabilized types makes it an equally useful pigment for other media. This applies especially for water-based systems. Textile printing, paper mass coloration, paper surface treatment, and paper pulp are areas of application as suitable for the use of P.B.15 as office articles, including colored pencils, blackboard chalks for schools, and water colors. 

Under the designation P.B.15 4, the Colour Index lists (3-Copper Phthalocyanine Blue types which are stabilized towards flocculation. These products show largely the same coloristic and fastness properties as P.B.15 3 types, but often exhibit much better rheology. As with stabilized a-Copper Phthalocyanine Blue types, stabilization through surface treatment has proven to decrease the solvent fastness of 3-Copper Phthalocyanine Blue, sometimes considerably so, making the pigment more sensitive to aromatics, alcohols, ethylene glycol, and ketones. 

Dyes can be used to obtain transparent colours in polyester resins. Considerable care in their selection needs to be taken as most will quickly fade on the addition of catalyst to the liquid resin or on exposure of the cured resin outdoors. However, certain quinone-type aromatic-soluble dyes in the yellow-red range are extremely lightfast and transparent blues and greens can be satisfactorily produced using small quantities of the corresponding phthalocyanine pigments. 

Approximately 90% of the phthalocyanines (predominantly copper phthalocyanine) are used as pigments (qv). In addition, they have found acceptance in many types of dyestuffs, eg, direct and reactive dyes, water-soluble and solvent-soluble dyes with physical and chemical binding, a2o-reactive dyes, a2o nonreactive dyes, sulfur dyes, and vat dyes (1) (see Dyes Dyes, reactive). 

Metal-free copper phthalocyanine blue, ie. Pigment Blue 16 [574-93-6] is one of the eadiest forms of phthalocyanine. Environmental concerns about copper in pigments tended to increase the use of metal-free copper phthalocyanine, but certain shortcomings (greenish hue, lack of stabiHty in aromatic solvents) allowed only specialty uses (109). The stabiH2ed a-NC-type is used in certain automotive coatings. 

The chemistry of the three most important chemical classes of organic colorants, the azo, carbonyl and phthalocyanine classes, has been dealt with individually in Chapters 3-5 respectively. In this chapter, the chemistry of a further five chemical classes which are of some importance for specific applications is discussed. These classes are the polymethines, arylcarbonium ion colorants, dioxazines, sulfur dyes and nitro dyes. A section of this chapter is devoted to each of these, each individual section contains a description of the principal structural features which characterise the particular colorant type, together with an outline of the chemistry of the main synthetic routes. There are many other chemical types of dyes and pigments that do not fall into the categories previously mentioned, but which are neglected in this text either because they are commercially of little importance or because they have been less extensively investigated. 

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