Bleaching and dyeing; fluid treatment and chemical modification – Fluid treatment – Combined liquid and gas or vapor
Reexamination Certificate
2000-05-26
2002-11-26
Coe, Philip R. (Department: 1746)
Bleaching and dyeing; fluid treatment and chemical modification
Fluid treatment
Combined liquid and gas or vapor
C008S149300, C068S00500D
Reexamination Certificate
active
06485526
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for continuous thermal treatment of a textile product web, in particular for dye fixing, as well as to an arrangement for performing the inventive method.
During coloring it is necessary to fix a dye applied on the textile product web. The dye fixing can be performed by retaining the product web with applied dye solution at room temperature or the moist or dried product web at higher temperatures. The fixing treatment depends on the material of the product web and the applied dye.
During coloring of chemical fibers with dispersion dyes, for example it is known to first dry the product web with applied dying solution and subsequently to fix the dye at higher temperatures on the product web.
German patent document DE/A 16 35 140 discloses a method of continuous dye fixing of chemical fibers in product webs by a high temperature treatment with convective heat transfer, for example from nozzle-aerated fixing tension frames. For blending of the fixing effect first a fast heating and subsequently a tension treatment is performed. During the fast heating the product web is guided in tensioning chains and during the retention treatment over normal guiding rollers.
During coloring of cotton or cellulose with reactive dyes it is for example known to first dry the product web with the dye solution applied to it and subsequently to let the dye react at higher temperatures with the fibers of the product web. For this first purpose a promoter, such as urea, is required, which is mixed to the dye solution. The promoter holds the dye in solution during drying and evaporates during fixing. As a treatment gas, heated air is used. The use of an aggressive promoter, such as urea, can be reduced or avoided by treatment of the product web with applied dye solution with a steam-air mixture.
From the patent document EP/A 0 864 683 it is known to impregnate a product web of cellulose knit or woven fabric with an aqueous dye solution of a fiber-reactive dye at a temperature of 20-25° C. to compress it, and to fix it without intermediate drying in an unsaturated water steam-air mixture, with 10-80 vol. percent of water steam, at a temperature of 100-160° C. and with an adjustable wet temperature of the moist product between 50 and 95° C. The product is guided with a speed, which is regulated by the measured residual moisture of the product after exit from the fixing device. The residual moisture amounts to 10-25 weight percent with respect to the product weight.
The patent document WO 97/14839 discloses a corresponding method and a device for dye fixing of cellulose products with reactive dyes, in which an optimal dye yield is obtainable without aggressive promoter quantities. In a padder the dying solution is applied on the product, and is subsequently guided in a chamber of an air dryer. In this chamber a steam contact is maintained in the order of 25 vol. percent of air and is supplied so that the product of the outlet of the chamber has a reaction-ready residual moisture. For this purpose two regulating circuits are used, namely one for the steam content and another for the residual moisture of the product web. In other words during this process expensive measuring and regulating devices are needed. This fixing method requires, due to the retention time of the order of two minutes in a continuous process with a product web speed of for example 40 m/min, a product extent in the retention aggregate, here a hot flue, of at least 80 m. It is therefore not efficiently usable for small quantities to be colored (small meter lengths).
SUMMARY OF THE INVENTION
Accordingly, it is an object of present invention to provide a method of continuous thermal treatment, in particular for dye fixing, in which the treatment gas contains hot steam and which can be used efficiently for smaller meter length.
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 continuous thermal treatment of a textile product web for dye fixing, comprising the steps of applying a dye solution to a product web; transporting the resulting moist product web with the dye solution applied to it through at least one treatment chamber; bringing the moist product web with the applied dye solution in contact with a treatment gas in the treatment chamber. The treatment gas contains hot steam, i.e. overheated water steam.
It is another object of present invention to provide an arrangement with which the new method of thermal treatment can be performed efficiently and faster.
In keeping with these objects, another feature of the present invention resides, briefly stated, in an arrangement for continuous thermal treatment of a textile product web for dye fixing, comprising a steam-tight housing with at least one treatment chamber having at least one circulating device with at least one circulating fan, nozzle boxes arranged above and below the product web; a transporting device for substantially flat guidance of the product web through the housing, the transporting device including at least one roller conveyor arranged at a distance from a front wall of the housing. In the inventive method for continuous thermal treatment of a textile product web, the moist product web provided with dye solution is transported through at least one treatment chamber and is brought Into contact in the treatment chamber with a treatment gas, which is composed of hot steam. The treatment gas is at least 80 vol. percent, preferably 95-120 vol. percent, or, in other words, approximately pure hot steam. The temperature of the hot steam amounts to 105-230° C. The hot steam used in the method according to the invention is overheated water steam substantially at atmospheric pressure.
With a higher steam content, higher temperatures of the product web are reachable during the thermal treatment. In particular with pure hot steam the product web temperature is increased to substantially 100° C. The higher treatment temperature accelerates the reaction of the dye with the fibers during fixing of reactive dye on cotton or cellulose. This leads to lower fixing times, correspondingly lower retention times in a treatment device, and possibly smaller devices.
A higher steam content of the treatment gas accelerates, due to the condensation ability of the hot steam, the heating, which leads to a further reduction of the required retention time. In a surprising manner the inventive treatment method, despite the higher steam content and the higher product temperature, and thereby increased drying, leads to good fixing results. In other words, it leads to a good dye yield and a good coloring quality, which correspond to the results of the prior art.
The drying of the moist product web during the treatment with hot steam provides lower fixing times for complete fixing. This is achieved by an acceleration of the fixing process, i.e. the reaction of the reactive dye with natural fibers, such as cotton and cellulose, by the drying.
The input moisture of the product web provided with the dye solution of the reactive dye amounts to 40-80%. For many reactive dyes the use of urea can be dispensed with.
The temperature of the hot steam can be preferably 160-230° C. The higher temperature of the treatment gas and thereby the higher the temperature difference between the treatment gas and the product, the greater the heat transfer and thereby faster the heating time of the product web and the drying of the product web.
The retention time of the product web in the arrangement is 50-60 seconds, preferably 10-30 seconds. This time is sufficient for complete fixing for good dye yield and makes possible to have an arrangement with a smaller structural dimension.
In a surprising manner it has been determined that with the inventive method optimal fixing results are provided with a residual moisture of the product web smaller or equal to the equilibrium moisture under normal conditions, or in other words approximately 10% moisture
Babcock-Textilmaschinen GmbH
Coe Philip R.
Striker Michael J.
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