Abstract:
Coloring of continuous textiles includes pad dying the textiles many times in at least one trough; subsequently green painting the textiles in an oxidation line; then washing and drying the textiles; and expelling oxygen from the textiles immediately before each pad dying, wherein a reintroduction of oxygen in the textiles is prevented before each green painting.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a method for continuous coloring textiles, as well as to the device for performing the method.  
         [0002]     Methods and devices of this type are known in the art, for example for indigo coloring of textiles, in which a coloring substance which is not soluble in water is converted by means of alkali or reduction agent into a water-soluble form which has affinity to threads. In this manner the coloring substance can color the threads of the textiles, which is also called pad dying. After a subsequent oxidation which is also known as green painting, the coloring substance obtains indigo blue color. Also, other copper coloring substances such as indanthrene and sulphur coloring substances can be used. The textiles in this application include textile webs or threads.  
         [0003]     German patent document DE 43 14 402 A1 discloses a method of indigo coloring of threads, in which the threads are pad dyed with a coloring substances many times and green painted in a subsequent oxidation line. Between the pad dying and the green painting the threads are damped. For this purpose the reaction times for the pad dying and the green painting must be shortened.  
         [0004]     German patent document DE 43 42 313 A1 discloses a device for application of indigo coloring substance, in which a thread assembly is guided via an inlet squeezing mechanism into a coloring substance emersion bath and further via an outlet squeezing mechanism of a retention line for extraction of the coloring substance. A wet retention line is arranged between the coloring substance emersion bath and the inlet squeezing mechanism, which is encapsulated against air entry and is held with low oxygen or oxygen free. Thereby a reduction of the chemicals consumption is provided.  
         [0005]     The disadvantage of the known methods and devices is that on the threads of the textiles a great quantity of oxygen adheres, for example on the outer surface or dissolved in the liquid, and therefore is introduced into the trough with the coloring substance. Thereby an undesirable oxidation of the coloring substance occurs, and of the auxiliary substances such as reduction agents and alkali in the trough. This leads to a high consumption of the chemicals with corresponding costs.  
       SUMMARY OF THE INVENTION  
       [0006]     Accordingly, it is an object of the present invention to provide a method for coloring of textiles, in which they are pad dyed many times with coloring substances and subsequently in an oxidation line are green painted, wherein the method and the device are improved so that considerable quantities of chemicals can be saved and simultaneously a uniform coloring result can be provided.  
         [0007]     In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method of coloring of continuous textiles, comprising pad dying of the textiles many times in at least one trough; subsequently green painting the textiles in an oxidation line; then washing and drying the textiles, which includes expelling of oxygen from the textiles immediately before each pad dying, wherein a reintroduction of oxygen in the textiles is prevented before each green painting.  
         [0008]     Since oxygen is expelled from the textiles directly before each pad dying, a further penetration of oxygen into the textiles before the green painting is prevented, and therefore it is excluded that undesired oxygen reaches the coloring bath.  
         [0009]     Oxygen in a coloring bath causes an oxidation of a coloring substance, so that it no longer has affinity to threads or in other words it is water-insoluble and can no more be used efficiently for coloring. Furthermore, the oxygen acts so that auxiliary substances such as reduction agents and alkali are consumed and/or converted into an inefficient form.  
         [0010]     Therefore, in the known methods more coloring and auxiliary substances must be dosed into the coloring bath than it is required by the threads themselves.  
         [0011]     The inventive method eliminates these disadvantages, and it prevents oxidation of coloring substances and auxiliary substances, without being used for the coloring process. When compared with known methods, a saving of 30-40% of the total consumption of chemicals with corresponding cost reduction is possible. Furthermore, coloring results are obtained.  
         [0012]     The expelling of the oxygen by emersion in a liquid and subsequent squeezing in accordance with another feature of the present invention guarantees its complete removal. The use of washing water guides chemicals, which are lost in known methods with the waste water, back into the covering process, so that they can be again utilized. The washing water is oxygen-free, it has the required pH value, and therefore it suits the best for the expelling of oxygen from textiles.  
         [0013]     The oxygen-free atmosphere between the expelling of the oxygen and the subsequent green painting prevents that the textiles, before or after wetting with a coloring substance, again take oxygen and introduce it then into the coloring bath. The maintaining of the once produced oxygen free atmosphere is possible with very low expenses, since in operation it is practically not influenced by the passing textiles.  
         [0014]     In accordance with another feature of the present invention a nitrogen atmosphere is utilized for the inventive method. Nitrogen is inert and price favorable.  
         [0015]     In accordance with another feature of the present invention, a device for coloring of textiles is proposed, which includes a plurality of coloring troughs each connected with a supply of a coloring substance; a second squeezing mechanism connected after each of said coloring troughs; a plurality of oxidation lines each arranged behind the second squeezing mechanism; a washing trough; a dryer; means for expelling oxygen from the textiles arranged immediately before each of said coloring troughs; further means which prevent a contact of the textiles with oxygen between each means for expelling and the second squeezing mechanism.  
         [0016]     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together ith additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection With the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The single FIGURE of the drawings is a view showing a diagram of a part of a device for coloring of threads in accordance with the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     A device for coloring textiles in accordance with the present invention has a plurality of wetting stages  1 . An oxidation line  2  and a washing device  3  follows each wetting stage  1 . Furthermore, the device in accordance with the present invention has not shown means for supplying threads  4 , in which the threads are wound for example in a bobbin by spools and supplied to coloring, and means for drying of the colored threads  4 .  
         [0019]     Each wetting stage  1  includes means for expelling oxygen  5  from the threads  4 , a coloring substance trough  6 , and a second squeezing mechanism  7 .  
         [0020]     The means for expelling  5  contain a trough  8  with at least one first deviating roll  9 , and a first squeezing mechanism  10  arranged at an outlet of the threads  4  from the trough  8 . An overflow conduit  11  is attached to the trough  8  and is connected with a drain.  
         [0021]     At a short distance in the running direction of the threads  4  behind the first squeezing mechanism  10 , the coloring trough  6  is provided with a plurality of second deviating rolls  12 . The threads  4  are guided over the second deviating rolls  12  so that they run a sufficiently along the line in the coloring trough  6 . The second squeezing mechanism  7  is arranged in the outlet region of the coloring troughs  6  above a coloring substance float level, so that the squeezed out bath float flows back into the coloring trough  6 .  
         [0022]     A region starting before the outlet of the threads  4  from the float of the trough  8  and ending behind the inlet of the threads in the second squeezing mechanism  7  is protected by further means from the surrounding atmosphere. For this purpose, a hood  13  is arranged so that it is immersed with its part into the float of the trough  8  and is substantially air tightly closed from the trough  8 , the coloring substance trough  6  and the second squeezing mechanism  7 . The hood  13  is connected through a not show conduit with a nitrogen source.  
         [0023]     After the squeezing mechanism  7 , the threads  4  pass through the oxidation line  2 . In this line they perform several deviations.  
         [0024]     Several combinations of the wetting stage  1  and the oxidation line  2  can be arranged, one after the other, as shown for example by the interruption by the threads  4 .  
         [0025]     A washing device  3  is arranged after the last oxidation line  2 . It includes a washing trough  14  as well as a sequence of third deviating rolls  15  and third squeezing mechanisms  16 . The washing trough  14  is connected by a conduit  17  with branches with each of the troughs  8 . Depending on space peculiarities, a pump  18  is arranged in the conduit  17 .  
         [0026]     Finally, a not shown dryer is arranged after the washing device  3 .  
         [0027]     In operation the threads  4  are pulled from the bobbin and guided as a thread assembly to coloring. For the coloring, one of the coloring processes described herein above is performed.  
         [0028]     The threads  4  which can take the oxygen from the air are first immersed in the trough  8  which is filled with washing water from the washing trough  14 . The washing water has a favorable pH value of approximately 11 or higher and contains residuals of coloring substance and auxiliary substances such as alkali and reduction agent. With these properties of the washer water, the oxygen is removed from the threads  4  substantially or completely, and the threads take a part of the coloring substance. In this way substantially less coloring substance and auxiliary substances must be dosed in the coloring trough  6 .  
         [0029]     After the immersion, the threads  4  are pressed in the first squeezing mechanism  10 , so that excessive liquid is squeezed out and flows back into the trough  8 .  
         [0030]     In the coloring trough  8  the threads are deviated over the second deviating rolls  11  so that they have a sufficient contact time for material exchange with the coloring float. In the coloring float the required quantities of water, coloring substance and auxiliary substances are dosed. Shortly before leaving the coloring float the threads  4  are again pressed in the second squeezing mechanism  7 . For this purpose the squeezing pressures in the first and in the second squeezing mechanism  10 ,  7  are identical, so that the threads  4  in the inlet of the color trough  6  have the same moisture as in its outlet, and an dilution of the coloring float is prevented.  
         [0031]     The whole region between the first and the second squeezing mechanism  7 ,  10  is provided under the hood  13  with an inert atmosphere. For this purpose during the starting phase of the device for coloring, the air under the hood  13  is replaced with nitrogen, which is supplied for example from a pressure gas container through the associated conduit. During the normal operation no or only an occasional post-dosing of nitrogen is required.  
         [0032]     From the outlet of the second squeezing mechanism  7 , the threads are supplied directly into the oxidation line, where the coloring substance is reacted with the air oxygen in the desired known manner.  
         [0033]     Depending on the requirements, several of the above mentioned device components—(wetting stage  1  and oxidation line  2 ) are connected in a sequence one behind the other, and the threads pass through several coloring steps one after the other.  
         [0034]     After the last coloring step, the threads are washed in the washing trough  14 . For this purpose they are immersed many times one after the other alternatingly in the washing trough  14 , and squeezed in the third squeezing mechanism  13 . Therefore excessive coloring substance and auxiliary substances are removed from the threads  4 .  
         [0035]     Finally, the threads  4  are dried and again processed, for example wound.  
         [0036]     Instead of the threads  4 , also other textiles, such as for example a web, can be treated in accordance with the present invention.  
         [0037]     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of methods and constructions differing from the types described above.  
         [0038]     While the invention has been illustrated and described as embodied in method of and device for covering of textiles, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.  
         [0039]     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.