Phthalocyanines textile dyes

In view of the immense commercial importance of phthalocyanines as pigments, it is perhaps surprising that only a few are of importance as textile dyes. This is primarily due to the size of the molecules they are too large to allow penetration into many fibres, especially the synthetic fibres polyester and polyacrylonitrile. An example of a phthalocyanine dye which may be used to dye cellulosic substrates such as cotton and paper is C. I. Direct Blue 86 (96), a disulfonated copper phthalocyanine. In addition, a few blue reactive dyes for cotton incorporate the copper phthalocyanine system as the chromophoric unit (Chapter 8). 

An appropriate ion-specific electrode was found to provide a convenient, precise and relatively inexpensive method for potentiometry of copper(II) ion in copper-complex azo or formazan dyes. Copper(II) ion in copper phthalocyanine dyes can be quantified after anion exchange. Twelve commercial premetallised dyes evaluated using this technique contained copper(II) ion concentrations in the range 0.007 to 0.2%. Thus many copper-complex direct or reactive dyes are likely to contribute low but possibly significant amounts of ionic copper to textile dyeing effluents [52]. 

The phthalocyanines, naphthalocyanines, and certain of their metal derivatives (Figure 6.17) are infrared fluorophores. 61"64 As a class, they are exceptionally stable compounds, with copper (Cu) phthalocyanine (not a fluorophore) remaining intact above 300 °C in air. First used for textile dyeing in the last century and still widely used, there is a rich chemistry of phthalocyanines. Most derivatives can be made by prolonged heating of a phthalimide or phthalic acid derivative with a metal in powder or salt form at elevated temperature. Several derivatives absorb in the near-IR, and either fluoresce or phosphoresce. The electronic transitions of phthalocyanines are complex and have been extensively studied, at least in part because the symmetry of the molecule makes theoretical calculations of its spectroscopic behavior more tractable. Unsubstituted phthalocyanines and naphthalocyanines are, as a class, very insoluble in solvents other than, for instance, nitrobenzene. Sulfonated phthalocyanines are water soluble and exhibit spectra comparable to the parent derivative. Photolumines-cent phthalocyanines (Pcs) include SiPc, ZnPc, and PC itself. These compounds have been little used for practical infrared fluorometry to date however, Diatron Corpora-... 

Phthalocyanine Dyes. In addition to their use as pigments, the phthalocyanines have found widespread appHcation as dyestuffs, eg, direct and reactive dyes, water-soluble dyes with physical or chemical binding, solvent-soluble dyes with physical or chemical binding, a2o reactive dyes, a2o nonreactive dyes, sulfur dyes, and wet dyes. The first phthalocyanine dyes were used in the early 1930s to dye textiles like cotton (qv). The water-soluble forms Hke sodium salts of copper phthalocyanine disulfonic acid. Direct Blue 86 [1330-38-7] (Cl 74180), Direct Blue 87 [1330-39-8] (Cl 74200), Acid Blue 249 [36485-85-5] (Cl 74220), and their derivatives are used to dye natural and synthetic textiles (qv), paper, and leather (qv). The sodium salt of cobalt phthalocyanine, ie. Vat Blue 29 [1328-50-3] (Cl 74140) is mostly appHed to ceUulose fibers (qv). 

Phthalocyanine pigments account for approximately 23% of the total worldwide organic pigment consumption of 225,000 tons. Approximately 20,000 t are used in printing inks, 10,000 t in paints, 9,000 t in plastics, 3,000 t in textiles, 7,000 t in dyes, and 2,000 t in specialty uses. Table 1 shows the worldwide distribution of cmde phthalocyanine capacity. The production history of phthalocyanine in the United States from 1980 to 1990 is given in Table 2 (161). The 1990 prices of phthalocyanine blue and green pigments were ca 11—22/kg and 21—27/kg, respectively. 

Other dyes in this group are phthalocyanine compounds which stiU have commercial importance, particularly in textile printing. 

Phthalocyanine Dyes. These days are synthesized as the metal complex on the textile fiber from, eg, phthalonittile and metal salts. A print paste typicaUy contains phthalonittile dissolved in a suitable solvent and nickel or copper salts. During a heat or steam fixation of 3—5 min, the dye is formed. The color range is restricted to blue and green shades and can be influenced to some extent by the choice of metal salt. A hot acid bath during afterscouting completes the process. 

Water-soluble phthalocyanine dyes may contain only sulfonic acid groups but normally contain both sulfonic acid and sulfonamido groups. They are used as direct dyes for paper and as reactive dyes for cotton. Representative examples are Cl Direct Blue 199 (38) and Cl Reactive Blue 71 (39). These dyes are also used for the ink jet printing of textiles (see Section 9.12.6.2). 

They were introduced in the late 1940s for the textile printing of cellulosic fabrics under the trade names Alcian (ICI) and Phthalogen (BAY). Both types resulted in the insolubilisation of copper phthalocyanine or related pigments within the fibre, although the respective application techniques differed considerably. Reactive phthalocyanine dyes in the 1960s superseded these early approaches to the attainment of fast bright blues and turquoises on cellulosic fabrics [63]. 

P.B.15 1, like other types of Copper Phthalocyanine, find extensive use in the spin dyeing of polypropylene, polyester, polyamide, secondary acetate, viscose rayon, and spun rayon. In these, as in other media, P.B.15 1 is very lightfast, and its textile fastness properties are almost entirely if not entirely satisfactory. 

P.B.15 3, like stabilized a-Copper Phthalocyanine Blue, markedly affects the hardening of unsaturated polyester cast resins. The list of applications also includes PUR foam materials, office articles, such as colored pencils, wax crayons, and water colors, as well as spin dyeing of polypropylene, polyacrylonitrile, secondary acetate, polyamide, polyester, and viscose. Used in polyester spin dyeing, P.B.15 3 satisfies the thermal requirements of the condensation process (Sec. 1.8.3.8). 1/3 and 1/25 SD samples equal step 7-8 on the Blue Scale for lightfastness. Textile fastnesses, such as stability to wet and dry crocking are perfect. 

Utilized in spin dyeing, P.Gr.7 lends color to all types of commercially important fibers. The products demonstrate excellent lightfastness and weatherfastness. Used in polyacrylonitrile, for instance, P.Gr.7 satisfies the stringent requirements for use in outdoor textiles such as canvasses. Its textile fastness properties are almost, if not completely satisfactory. This textiles field is another area in which Copper Phthalocyanine Blue types are more than twice as strong as P.Gr.7. 

Some coordination compounds have been used as dyes and pigments, but it must be admitted that these applications developed without reference to the fact that the compounds are complexes. Examples of paint pigments are Prussian blue and the phthalocyanines metallized azo dyes are common in the textile industry. 

History. Braun and Tschemak [23] obtained phthalocyanine for the first time in 1907 as a byproduct of the preparation of o-cyanobenzamide from phthalimide and acetic anhydride. However, this discovery was of no special interest at the time. In 1927, de Diesbach and von der Weid prepared CuPc in 23 % yield by treating o-dibromobenzene with copper cyanide in pyridine [24], Instead of the colorless dinitriles, they obtained deep blue CuPc and observed the exceptional stability of their product to sulfuric acid, alkalis, and heat. The third observation of a phthalocyanine was made at Scottish Dyes, in 1929 [25], During the preparation of phthalimide from phthalic anhydride and ammonia in an enamel vessel, a greenish blue impurity appeared. Dunsworth and Drescher carried out a preliminary examination of the compound, which was analyzed as an iron complex. It was formed in a chipped region of the enamel with iron from the vessel. Further experiments yielded FePc, CuPc, and NiPc. It was soon realized that these products could be used as pigments or textile colorants. Linstead et al. at the University of London discovered the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines from 1929 to 1934 [1-11]. The important CuPc could not be protected by a patent, because it had been described earlier in the literature [23], Based on Linstead s work the structure of phthalocyanines was confirmed by several physicochemical measurements [26-32], Methods such as X-ray diffraction or electron microscopy verified the planarity of this macrocyclic system. Properties such as polymorphism, absorption spectra, magnetic and catalytic characteristics, oxidation and reduc-... 

Stability of the Dye-Fiber Bond. Because of the large variety of reactive dyes, generalizations about colorfastness are difficult. While wetfastness is determined mainly by the anchor system used, most other fastness properties depend on the dye as a whole or the chromophore present. Most reactive dyes are azo or anthra-quinone derivatives whose standard of fastness varies greatly. Phthalocyanine, formazan, and triphenodioxazine derivatives are also very important. In addition, application conditions and finishing processes of the dyed goods can affect fastness properties. Thus, with some resin-finished textiles (dimethylolpropyleneurea finish) a decrease in lightfastness is observed. 

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