Monoazo lakes

Dainippon (1997fl). New crystalline monoazo lake color useful for printing inks— having specified diffraction peaks at various angles in x-ray diffraction pattern. Japanese patent 09194752-A. 

Dainippon (1991b). New crystal type red monoazo lake dye—for use as a barium lake dye substituent and as printing inks, coating etc. Japanese patent 09227791-A. Daniels, F., Williams, J. W., Bender, R, Alberty, R. A., Cornwell, C. D. and Harriman, J. E. (1970). Experimental physical chemistry, 7th edn. p. 53. McGraw-Hill, New York. [168]... 

Kobayashi, N. and Ando, H. (1988a). Red monoazo lake pigment Dainippon Inc. 

Kobayashi, N. and Ando, H. (1988fc). Monoazo lake for printing inks etc.—prepared by diazotizing 2-amino-5-methyl benzenesulphonic acid, coupling with 2-hydroxy-3-naphtholic acid and adding barium chloride solution. Dainippon Inc. Patent JP63-225 667 Chem. Abstr, 110, 77504. [26It]... 

Otomo, Y. Monoazo lake pigments and their use in printing inks. Jpn. Kokai Tokkyo Koho JP 04180969,... 

Most non-laked monoazo yellow and orange pigments are derivatives of the following structure ... 

A more traditional approach consists of introducing sulfonic acid substituents into yellow monoazo compounds. These can simply be precipitated, i.e., converted to lakes by salt formation, especially with calcium, and thus afford the more solvent and migration resistant monoazo yellow pigment lakes. 

Monoazo yellow pigments lakes are basically synthesized by introducing acidic groups into the diazo or coupling component and by precipitating the product as an insoluble salt. Usually the precipitation is carried out with salt solutions of calcium, barium, strontium or manganese. 

A number of commercially available yellow monoazo pigment lakes are based on a pyrazolone sulfonic acid derivative as a coupling component. An example is the aluminum tartrazine lake, listed in the Colour Index as Pigment Yellow 100,... 

Recent patents [5-7] also describe yellow pyrazolone monoazo pigment lakes based on the general structure... 

Introducing acidic substituents into the basic structure of a typical monoazo yellow pigment makes it possible to convert the material into a lake by salt formation. This improves the application properties of a pigment compared to its non-laked counterpart. Such pigments exhibit particularly good migration resistance and heat stability, making them useful colorants for plastics. 

Table 11 Non-laked monoazo yellow and orange pigments.

Tables 11 and 12 list the currently available non-laked monoazo yellow and orange pigments. Most of them carry a nitro substituent in the diazonium component, usually in ortho position relative to the azo bridge. The more migration-resistant Pigment Yellow 97 lacks a nitro group in its molecule. Seven monoazo yellow pigments are based on 2-nitro-4-chloroaniline or derivatives as a diazo component.

The currently available salt type monoazo yellow pigments are mostly based on 2-nitroaniline-4-sulfonic acid as a diazo component and are mostly sold as calcium lakes (Table 13). 

P.Y.169 is another calcium monoazo yellow pigment lake, which has been available for some years. Its hue is a reddish yellow. Its properties and application are similar to those of the much greener P.Y.168. 

The monoazo calcium pigment lake P.Y.190 is considered a specialty product for the coloration of plastics, but it has already been removed from the market. 

The monoazo ammonium lake is a recent product and differs in its coloristic and fastness properties scarcely from the calcium lake types. Therefore the recommended application media for the two lakes are the same. 0,34% P.Y.191 1 are required to produce 1/3 SD colorations (1 % TiOz) in HDPE. Such colorations are heat stable up to 300°C. 

BONA pigment lakes are monoazo pigments, characterized primarily by the following general chemical structure ... 

Diazotization of the aminosulfonic acid and subsequent coupling onto the sodium salt of 2-hydroxy-3-naphthoic acid initially affords the monoazo compound in the form of its soluble sodium salt. Subsequent reaction with chlorides or sulfates of alkaline earth metals or with a manganese salt, frequently in the presence of a dispersion agent, or rosin or its derivatives, at elevated temperature yields the insoluble BONA pigment lake. 

P.R.211 is offered only in the Japanese market. It is the calcium salt of a monoazo pigment. P.R.211 affords shades of scarlet which resemble those provided by Lake Red C types (P.R.53 1). The list of suitable media includes plastics and printing inks. Incorporated in these media, P.R.211 presents application and fastness prop-... 

Table 22 shows the monoazo pigment lakes which are based on naphthalene sulfonic acid (CP = coupling position). 

Non-Laked Monoazo Yellow and Monoazo Orange Pigments... 

Cl 15585 Lake red C Pigment red 53 Classification Monoazo color Empirical Ci7Hi2CIN2Na04S Properties M.w. 398.80 Toxicology LD50 (oral, mouse) >12 g/kg low toxicity by ing. mutagen carcinogenic in animals TSCA listed... 

Analogous behavior is shown by ten other monoazo dyes. The color differences between the alkaline solutions of the dye and the hydrosol of Mg(OH)2 dye lake are readily seen if the test is made on a spot plate Idn. Limit 0.1 y Mg). ... 

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