BONA Pigment Lakes

which is gaining commercial recognition in Europe, plays a certain role in the US market. The application properties of the pigment are quite similar to those of the Lake Red C types, P.R.53 1. P.O.46 produces a shade which is appreciably yellower than that of conventional P.R.53 1 types. Its shade is much more comparable to the color of the new, only recently marketed crystal modification of the barium salt of Lake Red C. 

Commercially available P.O.46 types are usually quite transparent. They are employed primarily in packaging printing inks, also in offset and metal deco printing. Publication gravure inks, plastics, especially PVC, LDPE, and elastomers, as well as general industrial paints are suitable media for pigment application. P.O.46 is less solvent resistant than P.R.53 1, but it is faster to alkali and acid. In terms of lightfastness, P.O.46 performs poorly 1/3 and 1/25 SD prints equal only step 1 on the Blue Scale. 

These pigments derive their name from 2-hydroxy-3-naphthoic acid, which is used as a general coupling component for the entire group. The compound is also known as beta-oxynaphthoic acid (BONA). 

The history of BONA pigment lakes parallels that of (J-naphthol pigment lakes. Literary evidence of the use of 2-hydroxy-3-naphthoic acid, which was first synthesized in 1887 by Schmitt and Burkard as a coupling component, dates from 1893 (Kostanecki). However, it was not until 1902 that the compound began to be employed in dye synthesis by AGFA (aniline - BONA). 

Pigment Red 57, discovered in 1903 by R. Gley and O. Siebert at AGFA, developed into one of the most important organic pigments in the market. It was first supplied in the form of its yellowish red sodium salt, to be converted to the calcium or barium salt by the consumer. 

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

BONA pigment lakes are basically synthesized like (3-naphthol pigment lakes. 

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. 

The majority of pigments within this group find extensive use in printing inks. There are also some products which are used primarily in paints. BONA pigment lakes play a role as colorants for plastics as well as for a variety of other media. 

As with p-naphthol pigment lakes, there is only a limited number of BONA pigment lakes that are marketed in large volume. Two of these pigments, however, maintain an important position within the pigments industry. Table 20 lists the currently available BONA pigment lakes. 

Table 20 Commercially available BONA pigment lakes.

Pigment Red 53, barium salt [5160-02-1] 15585 1 BONA (Ba salt) (Lake Red C) coupling of dia2oti2ed 2-amino-4-methyl-5-chloroben2enesulfonic acid with 2-naphthol, foUowed by salt formation... 

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