EP0455055B1 - Dyeing with reactive dyestuffs in standing baths following the exhaustion process - Google Patents

Description

The present invention relates to a process for the salt-saving dyeing of cellulose fiber material with reactive dyes from electrolyte-containing baths at 40 ° C to 130 ° C by the exhaust method.

Depending on the reactivity of the dye used, cellulose fiber materials such as cotton, cellulose materials and linen are usually dyed from dyebaths containing 5 to 120 g / l of sodium chloride or sodium sulfate, which, depending on the dyeing temperature, have a pH of 6 to 12 at 40 to 130 ° C.

With regard to the process control, a basic distinction is made between two principles in order to design the dyeing process so that a level, ie evenly dyed textile material is obtained.

In one method, the salt necessary for drawing up the dye onto the fiber material is added at the beginning of the dyeing process before the dye and in the other method after the dye has been added. The addition of the salt before adding the dye is preferred for technical reasons because of the easier handling. The start of the dyeing process with the liquor containing the salt is therefore a technically established procedure. The introduction of the salt into the dyeing liquor can be done by using salt, i.e. Let in a highly concentrated salt solution or by adding salt in solid form to the circulating liquor.

After the dyeing process has ended, the liquor containing the salt is drained off and the dyed textile material is cleaned of non-fixed residual dye by rinsing and washing. The salt content of the drained remaining liquor is 5 to 120 g / l depending on the color depth of the dyeing carried out.

The total salt consumption of the coloring is 2.5 to 250 kg per 100 kg of dyed material, depending on the color depth.

The salt content of the residual reactive dyeing liquors is therefore not only an ecological burden on the wastewater, but also represents a significant proportion of the total chemical costs to be used for the preparation of the reactive dyeing.

A process has now been found for dyeing cellulose materials from salt-containing baths with reactive dyes using the exhaust method, which is characterized in that the exhausted bath used for the previous dyeing is adjusted after the volume, salinity, initial pH value and dye concentration can be reused without further cleaning operation.

The reuse of a dye liquor that has already been used thus permits at least partial reuse of the amount of salt used for the previous dyeing.

The portion of the remaining liquor that remains in the material to be separated after dyeing when the material to be dyed and the remaining liquor are separated is removed by a repeated rinsing process. The amount of salt contained in the remaining liquor portion bound by the material to be dyed is thus transferred to the rinsing liquor and, because of its low concentration, is only of interest in special cases. However, the rinsing liquors can also be partially collected and used again for subsequent staining.

To reuse a dyeing liquor, the amounts of salt bound in the material to be dyed and removed by the rinsing process are replaced by adding fresh salt of the same type. Depending on the machine conditions, the amount of residual liquor bound by the material to be dyed is 200-300%, based on the amount of textile material used. Accordingly, by re-use of residual reactive dye liquors saves 1 to 200 kg salt (table salt or sodium sulfate) per 100 kg of the textile material to be dyed, depending on the color depth, liquor length and retention capacity of the goods.

The reuse of dyeing liquors is known in the textile industry under the name dyeing on standing baths and is used for dyeing various fiber materials. The dyeing of cellulose materials with reactive dyes on standing baths has not been described so far. On the contrary, there was a prejudice in the professional world against such a method, since it was assumed that in the subsequent coloring there would be shifts in tone and losses in yield. Surprisingly, this does not occur in the method according to the invention.

In a preferred embodiment, the dyeing time required to achieve the desired depth of color is extended by about 15-60 minutes and / or the dyeing temperature is increased after reaching the desired depth of color, for example by 10 ° C. to 20 ° C.

The dyeing is carried out in a known manner, for example by automated control of the addition of alkali or the pH (cf. Le A 25 166). It is expedient to use dyeing units which have a conductivity measuring cell for automatic control and adjustment of a defined electrolyte content.

The dyeing units expediently contain an additional vessel for holding the dyeing liquor mentioned.

Alkali metal hydroxides (LiOH, NaOH, KOH) are preferably used as the fixing alkali. Soda can also be used, for example.

The process according to the invention can be used to dye one after the other using the same or different dyes.

All water-soluble reactive dyes are suitable as reactive dyes, for example those of the azo, anthraquinone, phthalocyanine, formazane or triphendioxazine series.

The process is preferably suitable for dyes with a reactive substituent on a 5- or 6-membered aromatic-heterocyclic ring, for example a sym. Triazinyl, pyrimidinyl or quinoxalinyl ring. Possible reactive substituents are, for example, Cl, Br, F, ammonium, hydrazinium, pyridinium (with substituents such as COOH, CH₃).

The method is also particularly suitable for dyes with the grouping -SO₂CH₂CH₂X (X = Cl, OSO₃H) or the grouping -SO₂CH = CH₂. The process is particularly suitable for dyes with a monochlorotriazinyl, monofluorotriazinyl, mono-nicotinyltriazinyl, 2,6-difluoro-5-chloro-pyrimidinyl or 5-chloro-6-fluoropyrimidinyl radical.

example 1

100 parts of a bleached cotton material are treated for one hour in a dyeing machine with 2000 parts of a 50 ° C. aqueous liquor which contains 2 parts of dye I, 1 part of sodium bicarbonate, 12.6 parts of caustic soda and 100 parts of sodium chloride in solution.

Then the exhausted dye bath is allowed to drain into a storage container. The retention capacity of the goods is 300 parts of the fleet used. The expired fleet consists of 1,700 parts of the original fleet. The dyeing unit is then filled twice with fresh water at 60 ° C. and drained off after a treatment of 5 minutes. The drained fleet is led into the sewage system.

The dyeing is then treated twice with water at 80 ° C. for 10 minutes each. The stained fleets are drained. Then it is filled with 1700 parts of fresh water, brought to the boiling temperature and treated for 10 minutes. The liquor is drained, rinsed cold with fresh water and the dyeing is removed from the dyeing unit.

The dyeing unit is then loaded with 100 parts of a bleached, undyed cotton material. The 60 parts of sodium chloride in solid form are added to the remaining liquor of the first color transferred to the storage container and brought into solution by means of an agitator. The alkaline liquor is then adjusted to pH 6 using a dilute hydrochloric acid dissolved in 25 parts of water, the acid required being determined in a preliminary test. The neutral, saline liquor is then pumped back into the dyeing unit and heated to 50 ° C. After this temperature has been reached, a 50 ° C. warm solution of 4 parts of dye II in 150 parts of water is prepared while metering in linearly over 45 minutes.

Then 1 part of sodium bicarbonate dissolved in 25 parts of water at 50 ° C. is added in 15 minutes and then 1.38 parts of caustic soda dissolved in 100 parts of water at 20 ° C., metered in linearly over 60 minutes. After 60 minutes of dyeing at 50 ° C., the exhausted dye bath is allowed to run off in a storage container. The dyeing unit is then filled twice with fresh water at 60 ° C. and drained off after a treatment of 5 minutes. The drained fleet is led into the sewage system.

The dyeing is then treated twice with water at 80 ° C. for 10 minutes each. The stained fleets are drained. Then fill with 1700 parts of fresh water, to the boil brought and boiled for 10 minutes. The liquor is drained, rinsed cold with fresh water and the dye is removed from the dyeing unit.

A blue dyeing is obtained in the first dyeing process and a red dyeing with good fastness properties in each case in the second dyeing process.

Example 2

100 parts of a bleached cotton material are treated for one hour in a dyeing machine with 1000 parts of an 80 ° C. aqueous liquor of pH 9.4 which contains 2 parts of dye III, 2 parts of sodium bicarbonate, 4 parts of soda and 80 parts of sodium chloride. Thereafter, treatment is carried out at 95 ° C. for 10 minutes and the liquor is pumped off and transferred to a batch vessel which has a volume which corresponds to 100% of the dyeing volume of the dyeing unit. The pumped out fleet consists of 700 parts of the original dyeing fleet.

The dyeing unit is then filled twice with fresh water at 60 ° C and drained after 5 minutes; the drained fleet is fed into the sewage system. The dyeing is then treated twice with water at 80 ° C. for 10 minutes each. The stained fleets are drained. Then fill up with 700 parts of fresh water Brought to boiling temperature and treated for 15 minutes. Then it is rinsed with cold water and the dye is removed from the dyeing unit. The dyeing unit is then equipped with 100 parts of a corresponding undyed cotton material. The residual liquor of the first dyeing transferred into the batch vessel is adjusted to pH 6 with 100 parts of an aqueous solution containing dilute hydrochloric acid and 100 parts of an aqueous solution are added which contain 20 parts of sodium chloride, then 2 parts of dye III are dissolved in 100 parts Water was added and the dye liquor obtained was transferred to the dyeing unit.

The liquor is heated to 80 ° C. and allowed to circulate with the goods for 30 minutes.

Subsequently, 100 parts of an aqueous solution, which contain 2 parts of sodium bicarbonate and 4 parts of soda, are metered in uniformly over a 30-minute period with vigorous liquor circulation according to a linear dosing curve.

The dyeing is then carried out for 1 hour at this temperature and then the remaining liquor is pumped off, as in the first dyeing, and the dyeing is rinsed and aftertreated.

Instead of a total of 160 parts of table salt, only 100 parts were required for the two dyeings in the usual process, each with a new dye liquor. The process can be repeated any number of times by adding the shortage of 20 parts of table salt as well as dye and water.

Claims (3)

1. Process for successive dyeing of cellulose fibre materials with reactive dyestuffs by the exhaustion process from a single bath, characterized in that the exhausted bath used for the preceding dyeing is re-used without a further purification operation, after adjustment of the volume, salt content, initial pH and dyestuff concentration required for the respective subsequent dyeing.
2. Process according to Claim 1, characterized in that after the desired depth of colour has been reached, the bath is kept at the corresponding dyeing temperature or at 10 to 20°C above the corresponding dyeing temperature for 15 to 60 minutes.
3. Process according to Claims 1-2, characterized in that the rinsing liquors from the preceding dyeing are employed for topping up the dyebath of the preceding dyeing.