Organic compounds -- part of the class 532-570 series – Organic compounds – Azo
Patent
1993-03-26
1996-04-16
Richter, Johann
Organic compounds -- part of the class 532-570 series
Organic compounds
Azo
8527, 534637, 534642, 534887, C09B 4100, C09B 6726, D06P 1384
Patent
active
055083897
DESCRIPTION:
BRIEF SUMMARY
more important in recent years, since liquid dye preparations offer some significant advantages over the traditional powder forms, such as no dusting when making up padding or dyeing liquors or print pastes, easy meterability and no clumping due to inadequate wetting, but also thorough and efficient dispersion in the application medium with the attendant satisfactory dyeing results. In addition to meeting the many requirements which liquid dye preparations have to meet, for example the long storage life over a wide temperature range, even at temperatures below freezing, ready miscibility with water and other liquid dye preparations, such liquid dye preparations should have very high dye concentrations to reduce transport and packaging costs. The preparation of these highly concentrated dye solutions should be possible entirely reproducibly without major technical effort. dyes by direct means is difficult or even impossible because the diazotization and coupling reactions give rise to very viscous phases which, in the apparatus customarily used for dye synthesis, lead to serious stirring problems or make stirring completely impossible. As a consequence, the dye syntheses are distinctly slowed or remain incomplete, the formation of polluting by-products increases, or, because of the appearance of pasty reaction mixtures, the dye syntheses come to a stop entirely. carried out in dilute aqueous solutions, and the dye content is concentrated only afterwards by partial dewatering, for example with the aid of thin film evaporators or by membrane separation techniques. A further possibility of obtaining more concentrated solutions after synthesis is to separate off the as synthesized dyes in suitable precipitation reactions, for example by precipitating anionic dyes in a more acid region and separating them off by filtration and by subsequent renewed dissolving of the resulting dyes in water by means of an alkaline agent to obtain more highly concentrated weakly acid to neutral dye solutions. additional frequently appreciably high apparatus requirements, distinctly increased energy requirements and increased personnel and time requirements and, owing to the possible production of large quantities of salt- and dye-containing permeates or mother liquors, are highly polluting of the environment. the diazotization batch of 1-amino-2-naphthol-4-sulfonate acid is known from U.S. Pat. No. 2,812,321, according to which polyoxyethylene fatty acid esters are added to the batch. However, the viscosity-reducing effect of these polyethoxylated fatty acids is still insufficient. diazotization and coupling reactions can be carried out in highly concentrated solutions of these starting components and that in this way it is possible to prepare highly concentrated aqueous solutions of anionic azo dyes, preferably those which possess a fiber-reactive group, or a mixture of a highly concentrated dye solution with a suspension of the dye in a technically simple, inexpensive, highly reproducible and, in particular, environmentally safe manner by carrying out the diazotization and/or coupling reaction in aqueous medium in the presence of an auxiliary which has a viscosity-reducing effect on the pasty phases which appear at high concentrations. These measures prevent the appearance of pasty reaction mixtures having the above-mentioned serious disadvantages, and the diazotization and coupling reactions can be carried out rapidly and substantially completely without formation of environmentally polluting by-products. preparing concentrated aqueous dye solutions of anionic dyes having a dye content of preferably 15 to 40% by weight, in particular from 15 to 35% by weight, especially between 20 and 30% by weight, which comprises carrying out the diazotization of the aromatic amine serving as the diazo component and/or the reaction of the diazonium compound of the aromatic amine with the coupling component in an aqueous medium at a total concentration of diazonium and coupling compound of at least 10% by weight, preferably from 15 to 40% by w
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Hohmann Kurt
Mischke Peter
Schwab Eckhard
Sittig Manfred
Hoechst Aktiengesellschaft
Powers Fiona T.
Richter Johann
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