2,2’- acid fluorescent whitening agent

Fluorescent whitening agents (LD) Create a brightening effect Substantivity on fabrics Compatibility with other ingredients like bleaches Bistriazinyl derivatives of 4,4 -diamino-stilbene-2,2 -disulfonic acid 0.1-0.5%... 

Synthetic Fibers. Most synthetic fibers are sufficiently white and do not require bleaching. For white fabrics, unbleached synthetic fibers with fluorescent whitening agents are usually used. When needed, synthetic fibers and many of their blends are bleached with sodium chlorite solutions at pH 2.5—4.5 for 30—90 min at concentrations and temperatures that depend on the type of fiber. Solutions of 0.1% peracetic acid are also used at pH 6—7 for 1 h at 80-85°C to bleach nylon. 

Walther obtained the first direct dyes by self-condensation of 4-nitrotoluene-2-sulfonic acid. So-called Sun Yellow is a mixture of different components, depending on the concentration of sodium hydroxide, the temperature, and the duration of the reaction. Oxidation of the intermediate dye and subsequent reduction with iron and hydrochloric acid gives 4,4 diaminostilbene-2,2 -disulfonic acid, which is used for fluorescent whitening agents and azo dyes. The shades are mostly yellow to red. The structure of Direct Yellow 11, 40000 [65150-80-3] (13 is one of the main components) probably contains a mixture of stilbene, azo, and/or azoxy groups. 

Fluorescent whitening agents based on 4,4 -diaminostilbene-2,2 -di-sulfonic acid, cf. Figure 1.10, with different numbers of sulfonic acid... 

Uses Leveling agent, dispersant for dyeing polyester fibers with disperse dyestuffs, fluorescent whitening of polyester fibers with disperse FWAs and dyeing the polyester component of polyester/cellulosic blends by the HT process Features Prevents filtration of dyestuffs does not inc. the AOX content of waste-water pumpable resist, to acids, alkali, salts, hard water Properties YIsh.-brn. Iiq. readily sol. in water dens. 1.0 g/ml (20 C) pH 4,0 (10%)... 

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