CS249178B1 - Tannery auxiliary and method of its production - Google Patents

Abstract

Tannery auxiliary suitable for use during tanning and finishing of leather or for the preparation of other products, containing 5 to 70% by weight of nitroso derivatives of 2-naphtholdisulfonic acids, 1 to 15% by weight of nitroso derivatives of 2-naphtholmonoacids, 1 to 20% by weight of 2-naphtholsulfonic acids, 1 to 20% by weight of 2-naphtholdisulfonic acids, 0.5 to 15% by weight of 2-aphtholtrisulfonic acids, 1 to 35% by weight of sulfuric acid, 1 to 30% by weight of inorganic salts and 20 to 85% by weight of water. The new auxiliary agent is produced by nitrating the filtrates after the isolation of 2-naphthol mono- and disulfonic acids with alkali metal nitrite at a temperature of 0 to 80 °C, preferably 15 to 25 °C in a molar ratio of nitrite:2-naphthol sulfonic acid of 0.4:1 to 1:1 and the resulting product is subsequently separated by filtration or centrifugation.

Description

The present invention relates to a tanning aid suitable for use during tanning and dressing of leather or to the preparation of other products and to a process for its preparation.

SUMMARY OF THE INVENTION The present invention is based on the preparation of a technical mixture of 2-naphtholsulfo acids and their nitrosoderivatives by nitrosation of the 2-naphtholsulfo acids contained in the waste filtrates after isolation of the 2-naphtholmono or disulfo acids.

The raw materials used for the preparation of tanneries are mostly 2-naphthol, 2-naphtholsulfoacids or technical mixtures of 2-naphtholsulfoacids, sulfuric acid and sodium chloride prepared by salting out the waste filtrates after isolation of 2-naphtholsulfoacids or condensates of these substances with formaldehyde. The use of 2-naphthol or 2-naphthol sulfoacids prepared by sulfonating pure 2-naphthol is disadvantageous, since 2-naphthol can be used far more advantageously to prepare more demanding products, e.g., organic dyes. When using the technical mixture of 2-naphtholsulfoacids isolated by salting-out, it is disadvantageous that the waste water is burdened with salts added as salting-out agent, moreover, the salting-out produces a very difficult to filter product.

According to the invention, the disadvantages described are eliminated by using a technical mixture of 2-naphtholsulfone as a tanner auxiliary. acids and their nitroso derivatives prepared from waste filtrates after isolation of 2-naphtholmonone or disulfonic acids. by acid nitrosation with an alkali metal nitrite and isolating the product by filtration or centrifugation.

According to the invention, a tanning aid suitable for use during the tanning and dressing of leather or for the preparation of other products consists of 5 to 70% by weight. nitrosoderivatives of 2-naphtholdisulfoacids,

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- 2 1 to 15 wt. % of 2-naphtholmonosulfoacid nitrosoderivatives, up to 20 wt. % Of 2-naphtholmonosulfoacids, 1-20 wt.

% Of 2-naphtholdisulfoacids, 0.5 to 15 wt. % Of 2-naphtholtrisulfoacids, 1 to 35 wt. % sulfuric acid, 1 to 30 wt. % inorganic salts, 20 to 85 wt. water.

The preparation of the tanner auxiliary consists in that the filtrates after isolation of 2-naphtholmono and disulfo acids are nityosated with an alkali metal nitrite at a temperature of 0 to 80 ° C in a molar ratio of nitrite: 2-naphtholsulfoacid of 0.4: 1 to 1: 1 and the resulting the product is subsequently separated, by filtration or centrifugation, which product can be used directly or after drying.

The advantages of the process according to the invention can be seen in the use of waste naphtholsulfo acids and the saving of 2-naphthol. At the same time, the environmental problem in the current production of G-salts is solved.

This is illustrated by the following examples:

Example 1

% Of waste filtrates after isolation of 2-naphthol-6,8-disulfoacid containing 1.5 wt. 2-naphtholmonosulfoacids,

7.2 wt. % Of 2-naphtholdisulfoacids, 1.2 wt. % Of 2-naphtholtrisulfoacids, 30 wt. % sulfuric acid and 4.6 wt. In a boiler equipped with a stirrer and a dip tube, 160 kg of sodium nitrite dissolved in 540 l of water are mixed. The resulting suspension is filtered under suction and washed with 200 L of water to give 1200 kg of a paste containing 28 wt. % of nitroso derivatives of 2-naphtholdisulfoacids, 1 wt. % of nitroso derivatives, 2-naphtholmonosulfoacids, 3 wt. 2-naphtholdisulfoacids,

0.5 wt. % Of 2-naphtholtrisulfoacids, 1 wt. % Of 2-naphtholmonosulfoacids, 10% wt. % sulfuric acid, 56.5 wt. water. The resulting product may optionally be used as a tannery aid or as an intermediate in the production of other tannery aid. The leather treated with the composition thus obtained has a light color and a very good feel comparable or better when used with conventional preparations.

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Example 2

000 1 waste filtrates after isolation of 2-naphthol-1-sulfonic acid containing 1.6 wt. % Of 2-naphtolnonosulfoacids, 1.8 wt. % Of 2-naphtholdisulfoacids, 0.5 wt. % Of 2-naphtholtrisulfoacids, 15 wt. % sulfuric acid and 19 wt. of sodium chloride is mixed in a boiler at 30 ° C with 51 kg of sodium nitrite dissolved in 170 l of water. The _nickel slurry was isolated by centrifugation, to give 280 kg of product containing 30% by weight. % nitrosoderivatives of 2-naphtholdisulfoacids, 3 wt. % Of 2-naphthodisulfoacids, 0.5 wt. 2-naphtholmonosulfoacids, 11 wt.%, Sulfuric acid, 3.5 wt.%, Sodium chloride, and 52 wt. water. The resulting product is of a similar character to the product prepared according to Example 1.

Claims (3)

A tannerial aid suitable for use during tanning and dressing of leather or for the preparation of other products, characterized in that it is comprised of 5 to 70% by weight. % nitrosoderivatives of 2-naphtholdisulfoacids, 1 to 15 wt. % of 2-naphtholmonoa sulfoacid nitrosoderivatives, 1 to 20 wt. % Of 2-naphtholmonosulfoacids, 1-20 wt. % Of 2-naphtholdisulfoacids, 0.5 to 15 wt. % Of 2-naphtholtrisulfoacids, 1 to 35 wt. % sulfuric acid, 1 to 30 wt. % inorganic salts 20 to 85 wt. water. 2. A process according to claim 1, characterized in that the filtrates after isolation of the 2-naphtholmono disulfo acids are nitrosated with an alkali metal dilate at a temperature of 0 to 80 ° C, preferably 15 to 25 ° C in a molar ratio of nitrite: 2-naphtholsulfoacid 0. , 4: 1 to 1: 1, and the resulting product is subsequently collected by filtration or centrifugation. 3. A method according to claim 2, wherein the product is neutralized and optionally thickened after separation.