Лако-красочные материалы — производство

Condensation Reactions. Many triaminotriarylmethane dyes can be produced by condensation of Michler’s ketone (9) with aromatic amines. The ketone must generally be activated with phosgene or phosphorus oxychloride, whereby a reac­tive blue chloro compound (10) is formed from the intermediate geminal dichlor­ide. With N-phenyl-1-naphthylamine, for example, (13) reacts to form Victoria blue B (11). N(CH3)2 […]

The diphenylmethyl and triphenylmethyl cations can be considered the basic chromophores of di — and triarylmethane dyes [1-4]. However, the electronic state of the donor-substituted di — and triarylmethine dyes can be described better by breaking down the chromophore of these dyes into a straight — or branched-chain polymethine subchromophore, respectively, and two ethylene units […]

2.6.1 Introduction Di- and triarylcarbenium dyes [1] belong to the class of polymethine dyes and can be considered as branched polymethines. The branches are created by two aryl rings, in which the polymethine chain is incorporated, and by another R group bonded to the central (meso) methine carbon atom (1). The R group possesses я-electrons […]

The styryl dyes are neutral molecules containing a styryl group C6H5CH==C, usually in conjugation with an N, N-dialkylaminoaryl group. Styryl dyes were once a fairly important group of yellow dyes for a variety of substrates. They are synthesised by condensation of an active methylene compound, especially malo — nonitrile (9, X = Y = CN), […]

Diazahemicyanine dyes are arguably the most important class of polymethine dyes. They have the general structure (6). The heterocyclic ring normally contains one (e. g., pyridinium), two (e. g., pyra — zolium and imidazolium), or three (e. g., triazolium) nitrogen atoms, or sulfur and nitrogen atoms, e. g., (benzo)thiazolium and thiadiazolium. Triazolium dyes (7) provide […]

The hemicyanine dyes can be represented by structure (5). They may be consid­ered as cyanines in which a benzene ring has been inserted into the conjugated chain. Hemicyanines provide some bright fluorescent red dyes for polyacryloni­trile .

The general synthesis of the most important dyes within this group, e. g. the cya­nine dyes, is described in Section 5.7. 2.5.2 Principal Properties and Classification 2.5.3.1 Azacarbocyanines A cyanine containing three carbon atoms between the heterocyclic rings is called a carbocyanine (3, n = 1). Replacing these carbon atoms by one, two, and three […]

2.5.1 Introduction Methine dyes and polyene dyes are characterized by a chain of methine groups that forms a system of conjugated double bonds. The methine chain in polyene dyes is even-numbered and the terminal groups do not affect the excitation of electrons in the dye. The most important group of polyene dyes, the carotenoids, bear […]

Cationic dyes exhibit good affinity for negatively charged wood pulp and unbleached pulp grades. Anionic fixing agents improve their wetfastness. Cat­ionic dyes are chosen because of their brilliance and intensity, which makes them especially valuable for recycled paper grades. Their poor lightfastness is not a maior problem because of the low light stability of the […]

Glenz and Beckmann [24] were the first to investigate color balance and surface potentials in polyacrylonitrile fibers. On the basis of their results, they proposed the following dyeing mechanism: The cationic chromophore is first absorbed by the negatively charged fiber surface and then diffuses, at elevated temperature, into the interior of the fiber; there it […]