DE102006037811B3 - Chroming method for top-/after-chroming fiber materials dyed with top-/after-chroming colors uses a chromate compound produced from a water-soluble chromic compound oxidized in an aqueous substance - Google Patents

Abstract

A water-soluble chromic compound is oxidized in an aqueous substance to produce a chromate compound. The resulting solution is fed directly to top-/after-chroming. A basic chromium sulfate or potash chrome alum is used as a water-soluble chromic compound. Anodic oxidation occurs through a chemical oxidation agent. An independent claim is also included for a device for top-/after-chroming fiber materials dyed with top-/after-chroming colors.

Description

Nachchromierungsfarbstoffe are due to their high level of authenticity and the excellent Reproducibility of the dyeings produced for many decades important and much used component of the coloring of fiber materials made of polyamide, wool and comparable textile and non-textile native and synthetic proteins. This high level of authenticity and this excellent reproducibility of the dyeings are only achievable when compounds of chromium (VI) are used for the recchelling, which are reduced in fiber and one between fiber and dye form an immobile dye complex. Wool, for example dyed this way, this acts as a reducing agent.

Chromium (VI) But connections are associated with significant disadvantages. she cause acute inhalation dose-dependent allergic eczematous Skin reactions and present becomes its carcinogenic effect after long-term inhalation exposure discussed. The biggest exposure risk is therefore due to inhalation, especially when decanting, packaging and weighing, but also during transport and storage of chromium (VI) compounds can be done easily. Less problematic in this regard are chromium (VI) compounds in wastewater, especially since cleaning procedures already state of the art are.

in the Unlike chromium (VI) compounds, chromium (III) compounds act hardly toxic, chromium (III) is even considered essential for humans Trace element. In the body of an adult are stored between 0.4 and 0.6 mg of chromium (III).

Against this background, there has been no lack of attempts to completely avoid the handling of chromium (VI) compounds in the Nachchromierungsprozess. Advance to Color Science and Technology, Vol. 5, No. 1, Jan. 2002, describes the attempt to introduce the chromium (III) chromium necessary for complex formation on the fiber, for example by using chromium (III) salts in the presence of maleic anhydride to form a maleic acid / chromium (III) complex. Hydrogen peroxide acts as an oxidizing agent in this process to produce the chromium (VI) compound. J.Soc.Dyers and Colourists, 1993, 109 (5/6), 193-8 also describes the influence of the oxidation state of chromium on the result of the Rechroming, with the aim of avoiding chromium (VI). The CZ 293 743 B6 relates to a process for the rechroming of dyed with oxidizable chromium dyes of the azole type animal fibers, in particular wool, which instead of the usual chromium (VI) compounds, an oxidation of the dyes on the fiber with hydrogen peroxide, wherein the subsequent Nachchromieren carried out with trivalent chromium salts becomes.

Also according to JP 03174075 is chromed with trivalent chromium salts and achieved by the addition of fatty acids or amino acids, a high chroming effect.

It However, it has been shown that all these approaches become a coloristic, ecological or economically unsatisfactory result and a large-scale realizable alternative to the handling of chromium (VI) during use of chromophore dyes is not currently in sight.

Consequently there is still a significant need for a process that the disadvantages described when dealing with chromium (VI) compounds does not have, but equally good coloring results like the usual Nachromierungsverfahren provides.

• a) eine wasserlösliche Chrom-(III)-Verbindung in wässrigem Medium zur Chrom-(VI)-Verbindung oxidiert und anschließend
• b) die erhaltene Lösung direkt der Nachchromierung zugeführt wird.

According to the present invention, the described problem is solved by a process for the Nachchromieren of Nachchromierungsfarbstoffen dyed fiber materials with chromium (VI) compounds, characterized in that

• a) oxidizing a water-soluble chromium (III) compound in an aqueous medium to the chromium (VI) compound and then
• b) the solution obtained is fed directly to the Nachchromierung.

Surprisingly does that inventive method to the same good result as the known Nachchromierungsverfahren, working with analytically pure dichromate salt. The specialist would actually have expected that due to the direct use of the oxidation solution more Residual chromium remains in the wastewater. However, this is by no means the case, as in laboratory scale (10g to be colored Material), on a technical scale (500 g to be dyed Material), as well as on an industrial scale (100 kg to be dyed Material) has proven.

When water-soluble Chromium (III) compounds, which are preferably used in the process according to the invention can be can all chromium (III) salts, their anions under the conditions of Oxidation to chromium (VI) not oxidatively reacted and oxidant consume, be used. These are in particular halogen-free compounds, in addition to the chromium (III) no further oxidizable components contain. Particular preference is given, for example, to basic chromium sulfate and potassium chrome alum.

The oxidation of the trivalent to the six Chromium can be carried out by means of different processes, wherein chemical oxidizing agents can be used or anodic oxidation takes place.

In a first method of the invention the oxidation takes place in an acidic environment. Preference is given to the Chromium (III) compound with the addition of sulfuric acid, preferred in an amount of 5 to 10% of the molar amount of chromium (III) compound, at elevated Temperatures, especially at 80-90 ° C, dissolved and then by means of an oxidizing agent or anodized. Suitable oxidizing agents are, for example, the alkali metal peroxodisulfates, alkali metal peroxosulfates, as well as organic peroxo compounds with suitable oxidation potential. Particularly preferred is potassium peroxodisulfate, which advantageously at Cooking temperature is used.

In an alternative procedure, the oxidation of the chromium (III) compound takes place in alkaline Milieu. Preference is given to the chromium (III) with a slight excess of caustic soda as hydroxide like and this by means of peroxo compounds, such as alkali metal peroxodisulfates, Alkali metal peroxosulphates, organic peroxo compounds with suitable Oxidation potential, but preferably by means of hydrogen peroxide or Atmospheric oxygen or anodic to the chromium (VI) oxidized. Prefers Oxidation also takes place in alkaline medium at elevated temperatures. especially at 80-90 ° C. The mentioned oxidizing agents are preferably in a 10 to 30%, preferably 20%, excess, based on the stoichiometric required amount used.

Prefers will be the surplus oxidant after completion of the reaction by an approximately 5 to 10 minutes Cooking process destroyed.

Nachchromierungsfarbstoffe, the after coloration on fibrous materials, in particular polyamide, nachchromiert by the novel process can be are in the context of the present invention, all dyes that are initially on the Bind fiber material and then with the fiber material and chromium can form a sparingly soluble complex as the central atom. Such dyes are, for example, certain acid dyes, which are known to the person skilled in the art and are commercially available.

fiber materials In the context of the present invention, in particular polyamide fiber materials, the natural ones or of synthetic origin. Polyamide fiber materials of natural origin are in particular all common Forms of wool, for example of llama, alpaca, camel, mohair, Cashmere and angora kangaroo, hair such as bovine hair, Horsehair and pig bristles, and silk, such as Tussah silk and Mulberry silk.

synthetic Polyamide fibers are, for example, those of PA6, PA6.6, PA10 and PA12, but also sewing threads like Polyglycine and polyalanine and amino functionalized modified Polymers such as polyvinylamines and polyurethanes.

Of the in the dyeing machine Successive Nachchromierungsschritt takes place in a known manner and Way and does not differ from known methods in which the chromium (VI) compound is used directly. This method is known in the art and is described in detail in the literature.

In a preferred embodiment of the method according to the invention, becomes the oxidation of the chromium (III) compound to the chromium (VI) compound carried out in a special oxidation tank, the directly with the dyeing apparatus, in which the Nachchromierung takes place, is connected. The oxidation previous solution the chromium (III) compound in water can be in the oxidation tank, but particularly preferably it takes place in a special dissolving container, the in turn connected to the oxidation tank.

The The present invention thus also relates to a device for afterchroming of dyed with Nachchromierungsfarbstoffen fiber materials with Chromium (VI) compounds, characterized in that it is substantially an oxidation tank and a dyeing machine comprises, characterized, oxidation container and dyeing apparatus directly to each other are connected.

Prefers has the device according to the invention additionally a dissolving container, in which the solution the chromium (III) compound takes place and the one with the oxidation tank directly connected is.

Oxidation tank and Dissolving containers usually provide for chemical Implementation of suitable containers which is preferred over Supply lines for chemicals including the required pumps, exhaust duct, a stirrer, and a device to direct indirect heating of the container contents. to Acceleration of the implementation can the containers in place of or in addition to a stirrer Also be equipped with a circulation pump in the form of a secondary circuit.

such container are known in the art and can for sale be acquired.

It is also beneficial if solvent and Oxidation tanks have inwardly domed lids and effectively working splash rings to provide complete cleaning of the tanks.

Of the dyeing machine is usually one for dyeing with Nachromierungsfarbstoffen usual Dyeing machine. Such apparatuses are known to the person skilled in the art and are available on the market. Preferred dyeing machines are atmospheric or pressurized apparatus for dyeing flake, yarn, cables, Strand or piece goods, whose procedures are known to the skilled person. For piece goods one prefers to use Winch skids, jets and Baumfärbeapparate, and dyeing apparatus of ready-made goods.

Especially preferred devices according to the invention are constructed in this way, i. especially as far as possible closed, that a contact with the chrome solutions is largely excluded.

The inventive method, which comprises an oxidation in an acidic medium is used in the device according to the invention preferably done so that the chromium (III) compound in the dissolving tank or in the oxidation tank in Water dissolved and mixed with the required amount of sulfuric acid. Does the device have a separate dissolving container is the acid solution in the oxidation tank pumped and mixed there with the oxidizing agent. Otherwise, the addition of the oxidizing agent takes place in the same container, in that too the solution took place.

To Addition of the oxidizing agent causes the mixture to boil and kept at boiling temperature for about 15 minutes. The oxidizing agent can be added either in portions or continuously. After completion of the oxidation, the resulting chromium (VI) compound by means of a separate or a dyeing apparatus associated pump the pre-colored Fiber material supplied from polyamide, so that the dye-chromium complex can form with the material.

Should the oxidation takes place in an alkaline medium, so after the solution Chromium (III) compound and optionally after conversion of the solution into the oxidation tank the Chrome first as hydroxide by addition of a suitable amount of sodium hydroxide solution like and then the solution adjusted to pH 11-13. The mixture is then heated to> 85 ° C and under rapid Stir that Oxidizing agent added in about 10 min. After adding the mixture about 5 minutes brought to a boil and so a quantitative turnover achieved, as well as excess oxidant destroyed. The chromium (VI) forming in the form of a chromate now appears Use by adding sulfuric acid in the heat to the dichromate implemented, which is easy to change color from yellow to deep orange determine. The resulting mixture is fed directly to the dyeing apparatus and forms the dye-metal complex on the fiber.

Provided the oxidation of the chromium (III) compound anodically, i. electrochemically, should take place, the oxidation vessel is designed as an electrolytic cell. As such, it has in particular an anode and a cathode.

When Anode material is particularly suitable for inert materials such as coal, Graphite but also precious metals, such as platinum. The cathode material can be made of any conductive material, such as steel, Copper, graphite, coal and precious metals. As at the cathode during the Oxidation hydrogen forms, it must be derived harmless, i. the device must be over have a corresponding device.

It may be useful, cathode and anode compartment through a diaphragm to separate, with the solution in the anode and cathode chamber is preferably circulated by means of a pump.

The Anodic oxidation of the chromium (III) compound is preferred at room temperature.

The inventive method with anodic oxidation of the chromium (III) compound can in an apparatus according to the invention with formation of the oxidation tank be carried out as an electrolytic cell in an acidic or alkaline medium.

In In an acidic environment, the oxidation takes place, for example, at a voltage from 2.5 to 6 V, especially at 4V, in the presence of sulfuric acid and preferably a moderator. As a moderator, for example, are suitable small amounts of alkali or alkaline earth halides, in the simplest Case NaCl. The chloride is oxidized intermediately to the chlorine, which the oxidation of chromium (III) to chromium (VI) significantly accelerated. The chloride is regressed and the cycle starts again.

The Oxidation can be achieved by suitable chemical / physical measuring methods (such as AAS, icon chromatography, or chemical test kit) become.

example 1

a) Preparation of the chromate solution

In a 100 ml beaker 0.482 g of a 15% Cr ₄ (SO ₄ ) ₅ (OH) ₂ solution. weighed (15% based on the amount of Cr ₂ O ₃ , which would theoretically be found in the solution) and made up to a volume of 50 ml with PWK water. This solution is heated with stirring to 80 ° C and it is stirred throughout the entire reaction phase.

Then, 0.35 ml of 45% NaOH is added at 80-90 ° C to reach a final pH of 12-13. The result is a turquoise blue colloidal solution of the chromium oxide hydrate. 0.345 ml H ₂ O ₂ 35% are added to this colloidal solution at 80-90 ° C. so that only a slight foaming is visible. The final pH after the reaction should be clearly in the alkaline (typically pH 12). This produces a clear, pale yellow solution of the chromate. To destroy excess H ₂ O ₂ , this solution is heated to 100 ° C and the temperature is maintained for 15-20 minutes. The chromate is converted into the dichromate by addition of sulfuric acid until pH <3.

The solution obtained becomes directly for used the Nachchromierung.

b) staining with diamond black PV 200% of the company DyStar textile dyes GmbH on 10 g wool combed merino extrafine

10 g of Wollkammzug are packed in a suitable device and dyed at a liquor ratio of 1:15. For this purpose, the dyed material is introduced into the liquor and then 1.00 g / l sodium sulfate calc., 0.50% Sera ^® Sperse M-IS (Sera is a registered trademark of DyStar Textile dyes GmbH & Co. Germany KG) and 4, 00% acetic acid 60% added. After a short lead time through the liquor pump dissolved in hot water 4.00% diamond black PV 200% of the company DyStar textile dyes GmbH are added (based on product weight). The temperature is under liquor circulation with a gradient of 1 ° C / min. brought to 98 ° C (cooking temperature) and held for 45 min. At this temperature.

c) Nachchromierung

The produced according to a) Dichromate solution is the product dyed according to b) added to fresh bath (starting temperature 40 ° C) and with 2.00% formic acid 85% adjusted to pH 3.8-3.9.

The solution is heated to cooking temperature and held there for 45 minutes to to complete the formation of the chromium-dye complex. During the Implementation, the pH is kept near 4.

To Completion of the Nachchromierung lies the total chrome content in the Residual liquor at only 1.7 ppm.

In a reference dyeing made according to the standard method of the prior art the value between 1.3 and 1.9 ppm. Both values are below the For this Process required maximum limit of 2 ppm total chromium.

Example 2

coloring with diamond chrome pure blue B 150% and afterchroming on 10 g wool combing Merino extra fine

Analogous to the information in Example 1, 10 g Wollkammzug with the dye Diamond Chrome Pure Blue B 150% dyed and nachchromiert.

Of the Total chromium content in the residual liquor is only 0.8 ppm. In the reference coloring the standard method of the prior art is the value at 0.2 ppm. Both values are well below that for this one Process required maximum limit of 2 ppm total chromium.

Claims (7)

A process for the Nachchromieren of chromium (VI) compounds dyed with Nachchromierungsfarbstoffen, characterized in that a) a water-soluble chromium (III) compound in an aqueous medium to the chromium (VI) compound oxidized and then b) the obtained Solution is supplied directly to the Nachchromierung. Method according to claim 1, characterized in that as the water-soluble chromium (III) compound basic chromium sulfate or potassium chrome alum. Method according to claim 1 and / or 2, characterized in that the oxidation by means of a chemical oxidizing agent takes place. Method according to claim 1 and / or 2, characterized in that the oxidation takes place anodically. Apparatus for postchroming with post-chromating dyes colored Fiber materials made of polyamide with chromium (VI) compounds, characterized characterized in that it essentially comprises an oxidation tank and a dyeing machine comprises, characterized in that oxidation container and dyeing machine are directly connected. Apparatus according to claim 5, characterized ge indicates that it additionally comprises a dissolving tank, which is directly connected to the oxidation tank. Device according to claim 5 and / or 6, characterized in that the oxidation container as Electrolytic cell is formed.