Title:
Method and device for dyeing a textile substrate
Kind Code:
A1


Abstract:
A method for dyeing a textile substrate, in particular for dyeing a textile substrate with reactive dyes, is described in which the textile substrate is brought in contact with a dyeing liquor containing at least one dye and after a predetermined dyeing time has elapsed, the dyed textile substrate is rinsed. The at least one dye which has not been fixed by the textile substrate and is present in the dyeing liquor is destroyed by a chemical and/or physical treatment to such an extent that the dyeing liquor is largely colourless hereafter, whereby the textile substrate being rinsed with the largely decolourised liquor. A device for carrying out the method comprises a vessel for receiving the textile substrate to be dyed and a circulation system for the dyeing liquor, where a reactor through which the dyeing liquor flows is assigned to the vessel and/or the circulation system and where inside the reactor the chemical and/or the physical treatment of the liquor to be decolourised is carried out.



Inventors:
Ahmad, Nasir (Lahore, PK)
Shalkh, Irfan Ahmad (Lahore, PK)
Schmitz, Johannes (Coesfeld, DE)
Grafe, Karl Ludwig (Dulmen, DE)
Application Number:
12/081808
Publication Date:
05/21/2009
Filing Date:
04/22/2008
Primary Class:
Other Classes:
8/543, 68/55
International Classes:
D06B5/00; D06B3/20
View Patent Images:
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Primary Examiner:
DIGGS, TANISHA
Attorney, Agent or Firm:
Arlington/LADAS & PARRY LLP (ALEXANDRIA, VA, US)
Claims:
1. A method for dyeing a textile substrate, in particular for dyeing a textile substrate with reactive dyes, in which the textile substrate is brought in contact with a dyeing liquor containing at least one dye and after a predetermined dyeing time has elapsed, the dyed textile substrate is rinsed, wherein the at least one dye which has not been fixed by the textile substrate and is present in the dyeing liquor is destroyed by a chemical and/or physical treatment to such an extent that the dyeing liquor is largely colourless hereafter and that the textile substrate is rinsed with the largely decolourised liquor.

2. The method according to claim 1, wherein after a predetermined dyeing time has elapsed, the textile substrate is removed from the dyeing liquor and is transferred to an apparatus for rinsing, wherein the rinsing liquor laden with non-fixed dye is subjected to chemical and/or physical treatment.

3. The method according to claim 1, wherein the at least one dye not fixed by the textile substrate and present in the dyeing liquor or the rinsing liquor is destroyed by a chemical treatment.

4. The method according to claim 1, wherein an oxidative treatment is carried out as the chemical treatment.

5. The method according to claim 4, wherein a treatment with ozone is carried out as the oxidative treatment.

6. The method according to claim 1, wherein the dyeing liquor is separated from the dyed textile substrate and the chemical and/or physical treatment takes place thereafter.

7. The method according to claim 6, wherein the textile substrate is rinsed exclusively with the decolourised liquor.

8. The method according to claim 7, wherein the textile substrate is rinsed with the decolourised dyeing liquor in a first step, that in a second step the rinsing liquor laden with non-fixed dye is separated thereafter, that in a third step the non-fixed dye located in the rinsing liquor is destroyed to such an extent that the rinsing liquor is largely colourless and that in a fourth step the textile substrate is rinsed with the largely colourless rinsing liquor.

9. The method according to claim 8, wherein the first to the fourth step is repeated multiple times, in particular twice to fifteen times.

10. The method according to claim 1, wherein treatment with ozone is carried out as the chemical treatment of the dyeing liquor and/or the rinsing liquor and that the treatment with ozone is carried out in a reactor allocated to the respective dyeing apparatus, through which the dyeing liquor and/or the rinsing liquor flows continuously.

11. The method according to claim 10, wherein a redox potential measurement, an ozone measurement and/or a pH measurement of the ozone-treated liquor is made at the outlet of the reactor.

12. The method according to claim 11, wherein the quantity of ozone fed into the reactor is controlled depending on the measured redox potential, the measured ozone concentration and/or the measured pH value.

13. The method according to claim 1, wherein a fabric is dyed as the textile substrate.

14. A device for carrying out the method according to claim 1, comprising a vessel for receiving the textile substrate to be dyed and a circulation system for the dyeing liquor, wherein a reactor (6) through which the dyeing liquor flows is assigned to the vessel (12) and/or to the circulation system (16) and that in the reactor (6) the chemical and/or physical treatment of the liquor to be decolourised is carried out.

15. The device according to claim 14, wherein the vessel (12) for receiving the textile substrate to be dyed forms the reactor for carrying out the chemical and/or physical treatment.

16. The device according to claim 14, wherein a first piping system (19) for the dyeing liquor is located on the bottom region (15) of the vessel (12), which connects the reactor (6) via a first valve (20) and via a liquor pump (4) to the bottom region (15) of the vessel (12) and that the reactor (6) is connected by means of a second piping system (21) and a second valve (22) to the vessel (12) for supplying the largely colourless dyeing liquor after the treatment.

17. The device according to claim 16, wherein a heat exchanger (18) is assigned to the second piping system (21).

18. The device according to claim 16, wherein at least one sensor (7) for detecting the redox potential, the ozone concentration and/or the pH-value is assigned to the second piping system (21), wherein the at least one sensor (7) is located before the second valve (22) when viewed in the direction of flow of the liquor.

19. The device according to claim 14, wherein a device (1, 2, 3) for generating ozone is assigned to the reactor (6).

20. The device according to claim 19, wherein a third piping system (23) is allocated to the reactor (6), which piping system connects the air space in the reactor (6) to an exhaust air fan (9) via a residual ozone annihilator (8) and a third valve.

21. The device according to claim 19, wherein the ozone generator (1, 2, 3) is connected to a source for oxygen-enriched air.

22. The device according to claim 14, wherein the vessel (12) for receiving the textile substrate (13) to be dyed comprises a storage system assigned to the bottom region (15), that a deflecting device (14) for the web strand (13) is provided above the vessel (12), wherein the deflecting device (14) for the web strand comprises a driven mandrel and/or a nozzle channel.

23. The device according to claim 14, wherein the vessel has a dye beam for receiving a web strand.

24. The device according to claim 14, wherein the vessel has at least one holder for receiving at least one bobbin, in particular at least one cross-wound bobbin.

25. The device according to claim 14, wherein the liquor circulation system (16) is provided with a liquor circulating pump (17), a heat exchanger (18), a lint catcher and/or a colour trough.

Description:

The present invention relates to a method for dyeing a textile substrate having the features of the preamble of claim 1 and a device for carrying out the method having the features of the preamble of claim 13.

In order to dye textile substrates, and in particular in order to dye those textile substrates in which reactive dyes are used as the dye, it is known that the textile substrate is brought in contact with a dyeing liquor containing the dye or the dyes, where the dyed textile substrate is rinsed after a predetermined dyeing time has elapsed.

Depending on the respectively selected method and the equipment available in each case, a distinction is made between a pad roll dyeing, a pad steam dyeing and an exhaustion dyeing, but all the methods have in common that after the end of the actual dyeing process, rinsing is required to remove the non-fixed dye from the then dyed textile substrate.

This rinsing process required in any conventional dyeing method, which is also designated as soaping process in the field of reactive dyeing, in principle constitutes a multiply repeated dilution process so that a considerable amount of water is required for this. For example, a liquor ratio of 1:4 to 1:6 can be used for the exhaustion dyeing of a strand of a textile web, i.e. between about 4 litre and 6 litre of water is required for one kilo of textile substrate to be dyed whereas overall liquor ratios which vary between 1:80 and 1:200 are required for the actual rinsing process, this overall liquor ratio being obtained from the fact that the rinsing process must be repeated many times, for example, between four and eight times. In other words, when viewed as a whole, this rinsing process is on the one hand a very time-intensive processing step and on the other hand, a very water-intensive processing step.

It is the object of the invention to provide a method of the specified type whereby the dyeing of a textile substrate, in particular, the dyeing of a textile substrate with reactive dyes, can be configured particularly economically.

This object is achieved according to the invention by a method having the characterising features of claim 1.

The inventive method for dyeing a textile substrate, in particular for dyeing a textile substrate with reactive dyes, provides that the textile substrate is brought in contact with a dyeing liquor containing at least one dye and after a predetermined dyeing time has elapsed, during which the substrate is usually treated at an elevated temperature, the dyed textile substrate is rinsed. Contrary to the known dyeing methods described initially however, in the inventive method, at the end of the dyeing the at least one dye which has not been fixed by the textile substrate and is still present in the dyeing liquor is destroyed by a chemical and/or physical treatment to such an extent that the dyeing liquor is largely colourless hereafter so that the textile substrate is thereafter rinsed with the original dyeing liquor decolourised in this manner.

Specifically, the application of the inventive method to an exhaustion dyeing means that in this case, at the end of the dyeing by the exhaustion dyeing, the dyeing liquor is not discharged into the channel, but the dyeing liquor is subjected to a chemical and/or physical treatment in such a manner that the original coloured dyeing liquor is largely decolourised as a result, and can be further used hereafter for rinsing the dyed textile substrate. This decolourisation process can then be repeated, continuously or batchwise, sufficiently frequently until the non-fixed dye still present on the textile substrate is removed without residue so that when viewed overall, in the most favourable case in the inventive method only one single liquor is required for the dyeing and also for the rinsing. As a result, by using the inventive method, it becomes possible to dye and rinse textile substrates and in particular, textile substrates to be dyed with reactive dyes with a liquor ratio of 1:4 to 1:6 so that compared to the prior art described initially, four to six litres of water are required for dyeing and rinsing one kilo of textile substrate.

However, if the textile substrate is dyed by a pad roll dyeing or a pad steam dyeing, in the inventive method it is initially necessary to apply the dyeing liquor to the textile substrate depending on the degree of squeezing. About six hundred to nine hundred grams of dyeing liquor per kilo of textile substrate is required for this. After a predetermined roll time (dwell time) or steaming time has elapsed, the textile substrate thus dyed is preferably rinsed in a liquor ratio of 1:4 to 1:6 in which case, in the most favourable case in this variant of the inventive method, the first and only rinsing liquor then contains the dye which has not been fixed by the textile substrate and is present in the rinsing liquor, which is then destroyed by a chemical and/or physical treatment to such an extent that the rinsing liquor is thereafter largely colourless so that the textile substrate is then rinsed again with the largely decolourised liquor. This destruction of the dye and renewed rinsing with the then decolourised rinsing liquor can be repeated many times if necessary. consequently, this variant of the inventive method is also significantly more advantageous with regard to water consumption during rinsing compared to the conventional pad roll dyeing or conventional pad steam dyeing, especially as liquor ratios of 1:4.6 to 1:6.9 can be used in the inventive method.

In addition to the advantages described previously, the inventive method also has further advantages. It should first be noted that as a result of the considerably reduced water requirement of the inventive method compared to a conventional method, the quantities of waste water are accordingly also reduced considerably which is manifest in reduced environmental contamination and also in a considerably more favourable cost structure. Since in the most favourable case in the inventive method, only one rinsing bath is used, it is only necessary to heat this single rinsing bath once, whereas in the prior art where four to eight rinsing baths are used, these rinsing baths must be heated from room temperature to, for example, 80° C. again and again. In particular, since the inventive method dispenses with a liquor change during rinsing (soaping), the inventive method furthermore allows a considerable saving in time so that the throughput of substrate to be dyed per predetermined unit time is increased appreciably by using the inventive method. This in turn leads to a considerable saving in staffing capacity which has a positive influence on the economic viability of the inventive method. In addition, it could also, surprisingly for the specialist world, be established that the textile substrate dyed and in particular rinsed by the inventive method has a level of fastness, preferably a level of fastness in relation to wet rubbing fastness, dry rubbing fastness, washing fastness as well as water fastness and perspiration fastness which does not differ from textile substrates dyed by conventional methods.

In a first further embodiment of the inventive method, after a predetermined dyeing time has elapsed, the textile substrate is removed from the dyeing liquor and therefore from the apparatus used for the dyeing, and is transferred to another apparatus for rinsing. In this other apparatus, the actual rinsing process is carried out in such a manner that the dye which adheres and is not fixed to the textile substrate, is initially transferred to the rinsing liquor where the rinsing liquor laden with non-fixed dye is then subjected to a chemical and/or a physical treatment so that after the treatment the rinsing liquor is largely colourless and, if necessary, can be used for further rinsing. This further embodiment of the inventive method has the advantage that the rinsing process is carried out in the other apparatus which has a technically less complex structure compared to the actual dyeing apparatus so that such a working sequence can proceed in a particularly cost-saving manner.

A particularly suitable further embodiment of the inventive method provides that the at least one dye not fixed by the textile substrate and present in the dyeing liquor or the rinsing liquor is destroyed by a chemical treatment, where this chemical treatment is in particular an oxidative treatment.

In principle, all chemicals which allow the dye to be destroyed to such an extent that colourless degradation products are the result, can be used for this chemical and preferably oxidative treatment, where hydrogen peroxide or peracetic acid or sodium hypochlorite are preferably used for this purpose.

In the inventive method however, it is particularly suitable if the previously described oxidative treatment of the dyeing liquor at the end of the actual dyeing comprises a treatment with ozone or is carried out exclusively by a treatment with ozone, where it has been established that ozone destroys a plurality of different dyes and dye groups within the shortest time, i.e. within a few seconds to a few minutes, to such an extent that colourless dye degradation products are obtained, having no or only low substantivity to the textile substrate.

In principle, in the inventive method it is possible to treat the dyeing liquor at the end of the actual dyeing in a single bath to such an extent that the non-fixed dye which is still located in the dyeing liquor and on the surface of the textile substrate is decolourised by the chemical and/or the physical treatment. However, it is particularly suitable if the inventive method is varied so that the dyeing liquor is separated from the dyed textile substrate and the chemical and/or the physical treatment takes place thereafter so that accordingly, the dyeing liquor is preferably passed via a bypass to the actual dyeing apparatus and in this bypass, the dyes contained in the dyeing liquor are changed by a suitable chemical and/or a physical treatment to such an extent that colourless degradation products of the dyes are formed by this treatment. Accordingly, the dyeing liquor is then decolourised so that it is then used as colourless rinsing liquor again to rinse non-fixed dye from the dyed textile substrate. The dyed rinsing liquor thereby accumulating is then treated as described previously for the original dyeing liquor so that after the chemical and/or the physical treatment, this can accordingly be used again as colourless rinsing liquor for further rinsing.

For clarification, it should be noted that the term “and/or” used in the present text means that the individual elements in the corresponding listing can be seen as both additive or alternative, wherein with the additive designation, at least two elements of the listing are then combined with one another, whereas the term dye used in the singular naturally should cover not only a single dye but also a mixture of different dyes.

Physical treatment in the scope of the present application should be understood as all treatments which are suitable for destroying the dye to such an extent that colourless degradation products are formed as a result. Accordingly, the liquor thus decolourised can be used for the actual rinsing process.

It is particularly suitable if this physical treatment takes place by irradiating the coloured liquor to be treated with UV light and/or applying an electrochemical process using special diamond-coated electrodes, which are also designated as CVD electrodes in the specialist terminology.

As has already been explained hereinbefore, in the inventive method, in the favourable case, the dyed textile substrate is rinsed exclusively with the decolourised liquor at the end of the dyeing but in the inventive method, it cannot be excluded that at the end of the dyeing, which preferably comprises exhaustion dyeing, the dyeing liquor is drained and replaced by a single rinsing liquor which is then subjected to the chemical and/or physical treatment after contact with the dyed textile substrate in order to destroy the non-fixed dyes contained therein to such an extent that colourless degradation products and a colourless liquor are generated. This alternative of the inventive method can be used whenever the residual dye concentration in the dyeing liquor is so high that the expenditure for decolourisation by means of the chemical and/or physical treatment is too high and thus a single change of liquor is more favourable for economic considerations.

However, it is particularly suitable and economically favourable if in a modification of the inventive method in which the textile substrate is rinsed with the decolourised dyeing liquor in a first step, in a second step the rinsing liquor laden with non-fixed dye is separated thereafter, in a third step the non-fixed dye located in the rinsing liquor is destroyed to such an extent by the chemical and/or physical treatment that the rinsing liquor is largely colourless and that in a fourth step the textile substrate is rinsed with the largely colourless rinsing liquor.

Depending on which textile substrate is dyed with which dyes and to which colour intensity by the inventive method, an alternative of the inventive method provides that the first to the fourth step is repeated multiple times, in particular twice to fifteen times.

As has already been shown to be advantageous previously, an embodiment of the inventive method provides that treatment with ozone is carried out as the chemical treatment of the dyeing liquor and/or as the chemical treatment of the rinsing liquor, the treatment with ozone having the decisive advantage that the ozone decomposes again within the shortest time, i.e. a few seconds. In order to reduce the control and regulating expenditure as well as the safety expenditure in the inventive method, the treatment with ozone can be carried out in a reactor allocated to the respective dyeing apparatus or the rinsing device, where the dyeing liquor to be decolourised and/or the rinsing liquor to be decolourised flows continuously through this reactor. In other words, in this embodiment of the inventive method, the dyed textile substrate is separated from the ozone treatment stage of the dyeing liquor and/or the ozone treatment stage of the rinsing liquor so that it is accordingly ensured that the ozone does not acts on those dyes which are already fixed to the textile substrate.

In order to ensure that in the previously described particularly advantageous further embodiment of the inventive method, no decolourised liquor (dyeing liquor or rinsing liquor) still laden with residual ozone comes in contact with the dyed textile substrate, it has been shown to be particularly advantageous if a redox potential measurement, an ozone measurement and/or a pH-value measurement of the ozone-treated liquor is made at the outlet of the reactor. If the corresponding measured values should then indicate the presence of residual ozone in the correspondingly treated liquor, this residual ozone can be removed from the liquor by a short-term increase in temperature which can be achieved in terms of apparatus by providing another bypass here which is then triggered with such a residual-ozone containing liquor via corresponding valve settings.

As another possibility or in addition to the previously discussed variant, the inventive method is operated in such a manner that the quantity of ozone fed into the reactor is controlled depending on the measured redox potential, the measured ozone concentration and/or the measured pH value so that the quantity of ozone fed into the reactor is reduced accordingly when residual ozone is determined in the decolourised liquor.

In principle, the inventive method can be used in any dyeing method, in particular in the pad roll dyeing or pad steam dyeing described briefly at the beginning. In this case, after application and fixing of the dye, the textile substrate thus dyed is usually rinsed on a suitable installation, either continuously or discontinuously, and in this variant of the inventive method, the rinsing liquor is then subjected to the previously described chemical and/or physical treatment to destroy the dye contained in the rinsing liquor to such an extent that the rinsing liquor is largely colourless. The inventive method can just as well be applied to dyeing which is carried out on a jigger in the normal and high-temperature range. However, it is particularly appropriate if the inventive method is used in exhaustion dyeing methods since in this case, as described initially, a dyeing liquor is available which can be accordingly treated physically and/or chemically for decolouration. Likewise, there are no restrictions as to the form of preparing the textile substrate prior to dyeing (make-up of the textile substrate) to which the inventive method is applied. The inventive method can be also be used for yarn dyeing, either cross-wound bobbin or strand dyeing, but it is also suitable if the textile substrate as a textile fabric and preferably as a continuous web strand is dyed by the inventive method since the savings of water discussed previously are shown particularly clearly here.

The present invention further relates to a device for carrying out the inventive method as described previously, whereby the inventive method can be carried out particularly economically.

The inventive device for carrying out the inventive method as described previously in particular comprises a vessel (housing) for receiving the textile substrate to be dyed and a circulation system for the dyeing liquor, wherein a reactor through which the dyeing liquor flows is assigned to the vessel and/or the circulation system. Inside the reactor the chemical and/or physical treatment of the liquor to be decolourised (dyeing liquor at the end of the dyeing process and/or rinsing liquor) is carried out.

The previously described inventive device has all the advantages as these have already been before described for the inventive method. In particular, the inventive device allows a rational use of a textile substrate to be dyed by an exhaustion dyeing method, where disturbances and in particular undesirable damage of the dyed textile substrate is avoided by carrying out the actual physical and/or chemical treatment for discolouring the liquor in a separate reactor.

Likewise, it is possible to have an embodiment of the inventive device in which the vessel for receiving the textile substrate to be dyed forms the reactor for carrying out the chemical and/or physical treatment. In other words, in this embodiment the actual reactor is formed by the dyeing vessel itself or by a separately arranged other apparatus described previously in the inventive method, to which the textile substrate which has been dyed but not yet been rinsed is transferred for rinsing, so that the chemical and/or physical treatment is carried out following the dyeing in the dyeing vessel itself or in the other apparatus.

A particularly suitable and space-saving embodiment of the inventive device proposes that in this case, a first piping system for the dyeing liquor is located in the bottom region of the vessel in which the actual dyeing and rinsing takes place and this connects the reactor via a first valve and via a liquor pump to the bottom region of the vessel, the reactor being connected by means of a second piping system and a second valve to the vessel for supplying the largely colourless dyeing liquor or rinsing liquor after the treatment. Generally speaking, the bottom region of the vessel is connected via a valve and a liquor pump to the reactor and the reactor itself is again connected via a valve to the vessel so that the actual treatment step for the chemical and/or physical decolourising of the liquor takes place in this reactor which is connected as a bypass. At the end of the actual dyeing, the respective dyeing liquor is therefore supplied to the reactor with the aid of the liquor pump and a suitably opened first valve, the chemical and/or physical treatment of the liquor for destroying of the dye and therefore for decolourising the same is carried out there so that the thus decolourised liquor is then fed back to the vessel again via the second valve to initiate the actual rinsing process.

In order to ensure the required constant temperature in the previously described variant of the inventive device and in order furthermore, should this be necessary, to remove undesirable residues of ozone and/or other oxidation agents from the decolourised liquor flowing back to the vessel, a further embodiment of the inventive device provides that a heat exchanger is assigned to the second piping system.

Moreover, in another embodiment of the inventive device at least one sensor for detecting the redox potential, the ozone concentration and/or the pH value is assigned to the second piping system so that undesirable residues of oxidation agents and in particular, undesirable residues of ozone are detected by means of the at least one sense at a time before a liquor laden with such residual oxidation agents or residual ozone comes in contact with the dyed textile substrate, which can possibly lead to defects. In order to eliminate such an error source, the at least one sensor is located before the second valve when viewed in the direction of flow of the liquor, this second valve preferably being configured in such a manner that when an undesirable residual concentration of oxidation agents and in particular of ozone is detected the respective liquor stream is fed via the second valve, for example, to a heat exchanger, to expel these undesirable residues, and only then is the residue-free liquor fed to the vessel.

In the embodiments of the inventive device in which the non-fixed dye from the dyeing liquor or from the rinsing liquor is destroyed by ozone treatment to such an extent that colourless components are formed therefrom, it is possible to assign a device for generating ozone to the reactor, such devices being known per se in the prior art. Naturally, however it is also possible to act upon the reactor with ozone by providing suitable ozone storage tanks here. This variant is particularly suitable if the dyeing liquor still has a high concentration of non-fixed dye at the end of the actual dyeing process so that an increased amount of ozone is therefore used in the reactor in order to destroy this residual non-fixed dye by the ozone treatment to such an extent that colourless components are produced from this.

For safety reasons, it is recommended that in a further embodiment of the inventive device a third piping system is allocated to the reactor, which piping system connects the air space in the reactor to an exhaust air fan via a residual ozone annihilator and a third valve. In this case, it is furthermore particularly advantageous if a sensor for detecting the ozone concentration is provided in the exhaust air so that a corresponding audible or visual signal is optionally generated before exhaust air enriched with ozone can enter into the atmosphere.

In order that a sufficient quantity of ozone required for treatment of the dyeing liquor or the rinsing liquor is always available, another embodiment of the inventive device provides that the ozone generator is connected to a source for oxygen-enriched air so that the actual ozone generation accordingly takes place particularly rapidly directly before its use.

As has already been stated hereinbefore, the inventive device is used in particular for those dyeing methods using the exhaustion process where the inventive device is then accordingly adapted to the make-up of the goods to be dyed.

Thus, the first possibility provides that the vessel for receiving the textile substrate to be dyed comprises a storage system assigned to the bottom region, and a deflecting device for the web strand is provided above the vessel. Furthermore, the deflecting device for the web strand comprises a driven mandrel and/or a nozzle channel so that the web strand is therefore transported and folded continuously during the dyeing and also during the rinsing.

A second possibility which is particularly used for dyeing a web in the broad and bound state envisages providing a cylindrical vessel which is equipped with a dye beam (perforated beam) for receiving a web roll.

The third possibility further develops the inventive device in that the vessel has at least one holder for receiving at least one bobbin, in particular at least one cross-wound bobbin so that this variant of the inventive device is accordingly adapted for the bobbin dyeing.

In order to prevent undesirable disturbance of the process sequence in the inventive method or in the treatment of the textile substrate to be dyed in the inventive device, a liquor circulating pump, a heat exchanger, a colour trough (dye feed tank) and/or a lint catcher (fibre waste trap) is assigned to the circulation system through which the dyeing liquor flows during the actual dyeing process and the decolourised dyeing liquor at the end of the dyeing process or the decolourised rinsing liquor.

Advantageous further developments of the inventive method and the inventive device are specified in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic of the device of the invention.

The inventive method and the inventive device will be explained in detail hereinafter with reference to an exemplary embodiment of the inventive device. In this case, the single figure shows a schematic diagram of the inventive device.

The embodiment of the device designated overall as 11, shown in the single figure, initially comprising a conventional dyeing installation 10 provided with a vessel 12 for receiving the web strand 13 to be dyed. During the dyeing and rinsing the web strand 13 is transported continuously through the vessel 12, a driven mandrel 14 being used for transporting this web strand 13 in the embodiment shown.

A liquor circulation system 16 is assigned to the bottom region 15 of the vessel 12, where the respective treatment liquor is withdrawn from the vessel 12 via this liquor circulation system 16 by means of a liquor circulating pump 17 and a heat exchanger 18 and is fed into the vessel 12 again after heating the liquor. During the treatment, the web strand 13 is transported by means of the mandrel 14 at a predetermined speed in the direction of the arrow 19a, the transport speed usually varying between 200 m/min and 800 m/min. Furthermore, a lint catcher not shown and a colour trough are assigned to the liquor circulation system 16.

A reactor 6 is provided in a bypass to the dyeing installation 10, in which the actual chemical and/or physical treatment of the dyeing liquor or the rinsing liquor takes place, where in the embodiment shown, the non-fixed dye is subjected to a chemical treatment with ozone to destroy the dye to such an extent that colourless components are generated. The reactor 6 is connected via a line 3 to an ozone generator 2, where oxygen-enriched air is fed via the line 1 in the ozone generator. In addition, on the input side the reactor 6 is connected via a first piping system 19 to the bottom region 15 of the vessel 12, where a valve 20, a liquor pump 4 and a heat exchanger 5 are provided when viewed in the direction of flow of the liquor from the vessel 12 to the reactor 6.

In addition, the reactor 6 is connected to the bottom region 15 of the vessel 12 by means of a second piping system 21 via a sensor 7 and a second valve 22, again viewed in the direction of flow of the liquor.

Finally, a third piping system 23 opens from the reactor 6 to an exhaust air fan 9 which connects the air space provided in the reactor 6 via a residual ozone annihilator 8 to the exhaust air fan 9, where the exhaust air fan 9 is open to the atmosphere.

The device shown in the figure operates as follows:

Firstly, the dyeing installation 10 is provided with the textile web strand 13, where for this purpose the web strand 13 is made up as a continuous web strand and is positioned inside the vessel 12. The vessel is then filled with dyeing liquor in its lower region, where the liquor is continuously pumped around by means of the liquor circulation system 16 during the actual dyeing, and the web strand 13 is continuously transported. Such a dyeing installation 10 and its operating mode have been prior art for a long time before.

After the dyeing has now been completed in the dyeing installation 10, the dyeing liquor located in the vessel 12 is pumped continuously to the reactor 6 by opening the valve 20 and with the aid of the liquor pump 4 and via the heat exchanger 5 via the first piping system 19, whereby the liquor in the reactor still containing residual dye which has not been exhausted and fixed is treated with ozone in the reactor 6. In this case, the ozone is continuously created in the ozone generator 2 from the oxygen-enriched air supplied via the line 1 and is added to the reactor in a predetermined quantity by means of the line 3. The quantity of ozone is controlled so that on the one hand, the liquor leaving the reactor 6 is colourless and on the other hand, no more residual ozone is displayed on the sensor provided in the second piping system 21. However, should residual ozone still be detected here, the valves 20 and 22 provided in the piping systems 19 and 21 which are open during the treatment, are automatically closed. At the same time, the pump 4 is switched off so that the process in the reactor is interrupted instantaneously.

The liquor thus decolourised by means of the ozone treatment passes via the second piping system 21 and the opened valve 22 into the bottom region 15 of the vessel and rinses the dyed web strand 13 which is continuously transported at a predetermined speed in the direction of the arrow 19a.

After a predetermined time has elapsed which depends on the substrate to be dyed, the selected dye, the colour intensity, the liquor ratio and/or the loading of the vessel 12 as well as the transport speed, the rinsing process is now ended, and the residual ozone remaining in the system, in particular the residual ozone located in the reactor, is destroyed by means of the residual ozone annihilator 8 so that ozone-free exhaust air can be removed from the system via the exhaust gas fan 9.

The vessel 12 can then be ventilated and a dyed and perfectly rinsed web strand can be removed from the vessel 12 so that the previously described dyeing and rinsing process can be carried out with an overall liquor ratio of 1:4 to 1:6 in total.