Treatment Of Textile Materials

Abstract

Solvent laden textile materials are passed through a steam chamber and thereafter a hot water bath to remove the solvent therefrom. The combination of steam and hot water, in that sequence of steps, mitigates difficulties heretofore experienced in the art and improves the efficiency of processes for removing solvents from textiles.

Description

This invention relates to the treatment of textile materials and more particularly to processes for the removal of solvent from textile materials.

It has been known for some time that textile materials may be treated with organic solvents such as trichloroethylene and perchloroethylene to remove grease and like impurities and that the organic solvent may in turn be removed from the textile materials by passage of the material through a chamber in which it is contacted with steam. Removal of the solvent with steam has the considerable advantage that a fairly short treatment period (about 12 seconds) is in general required, but the steam treatment process also has the disadvantage, particularly when used in machines treating grey woven cloth at very high speeds, that size and sometimes lint may collect on rollers used to transport the textile material through the steam chamber and so cause creasing of the textile and sometimes, by making the squeeze rollers slimy, cause loss of traction between such rollers and the textile material. This problem becomes more marked when a complex system of rollers is used to get an adequate treatment time in a suitably small steam chamber. The problem of the deposition of size on rollers in the steam chamber may be overcome by desizing the material before it is passed through the organic solvent, but as is well-known in the art it is generally economically advantageous to carry out the desizing step after, and not before, the use of organic solvent.

It has also been known for some time that organic solvent may be removed from textile materials by passage of the material through a bath of hot water. However, this process has the disadvantage that it takes a comparatively long time (generally about 30 seconds) to remove all of the organic solvent and a treatment time of this duration when using very high rates of throughput of textile material necessitates a large and expensive piece of apparatus. Furthermore a copious evolution of the vapor of the organic solvent takes place at or near the point of entry of the material laden with organic solvent into the hot water bath. The turbulence created by this evolution of vapor is of advantage in a scouring process by promoting dislodgement of contaminants but is disadvantageous where dislodgement of a finish must be avoided. Furthermore when using very high rates of throughput a turbulence created by copious evolution of solvent vapor into a hot water bath can lead to the hot water surging into and overloading the condensing system for the solvent vapors if the cloth contains any substances having a tendency to produce foam.

We have now found surprisingly that a combination of both steam and water treatments permits of rapid removal of solvent from the textile material while mitigating some of the disadvantages associated with the use on their own of either a hot water or a steam "flash-off" system. Our process is particularly useful for the removal of solvent from cloth which has been treated by a solvent-scouring process to remove grease and wax.

Thus according to our invention we provide a process for removing an organic solvent from a textile material which comprises treating the textile material with steam and then with hot water whereby solvent is removed from the textile material during the treatment with steam and during the treatment with hot water.

The organic solvent may be any solvent used in the scouring of textile materials and in particular may be a chlorinated hydrocarbon solvent for example trichloroethylene, perchloroethylene, 1,1,2-trichloro-1,2,2-trifluoroethane or mixtures thereof.

The textile material may be of natural or man-made fiber and may be in any convenient form, for example, loose fiber, yarn, knitted fabric, woven cloth, carpets or lace but is most advantageously a woven cloth particularly one that contains water and/or solvent-insoluble sizing agents, for example starch, cellulose ethers, or polyvinyl alcohol applied to the yarn to facilitate weaving.

In the process of our invention a major proportion of the organic solvent may be removed rapidly in the steam chamber leaving only a minor proportion of the organic solvent to be removed by the hot water bath.

Indeed a very short treatment time of about 3 seconds in the steam is generally sufficient to remove well over 90 percent by weight of the organic solvent from the textile material, the remaining solvent being removed by the treatment with hot water. The most convenient steam treatment time will obviously vary with the process conditions and in particular with the type of cloth to be treated, for example a heavy cloth will in general require a longer treatment to remove a given proportion of solvent than will a light cloth. Likewise the most convenient time of treatment in the hot water bath will depend on the duration of the steam treatment and on the other process conditions, in particular the weight of the cloth to be treated. In general however we have found that suitable residence times in the steam treatment zone are between about 2 and 8 seconds and preferably between about 3 and 6 seconds, and in the hot water treatment zone are between about 5 and 20 seconds and preferably between about 8 and 15 seconds, but shorter or longer times may be used if desired.

The process of our invention helps avoid the formation of a foam of organic solvent and water at high rates of throughput, can enable fewer rollers to be used in the steam "flash-off" chamber (and therefore leaves less chance of the fouling of such rollers) and incorporates the advantages of a hot water bath in the loosening of size deposits on the textile material without incorporating the disadvantages of prolonged treatment and bulky apparatus normally associated with removal of solvent by hot water.

Apparatus suitable for carrying out our invention will be very similar to existing apparatus for removal of solvent from the textile material, in which a steam chamber is followed by an open water bath. However, the existing apparatus will have to be modified slightly, for example by enclosure of the water bath to prevent escape of organic solvent and by provision of cooling coils situated above the hot water bath on which volatilized solvent may condense and be collected. Also the path of the cloth through the steam chamber may be considerably reduced in length with corresponding reduction in the number of rollers in the chamber.

In general the times, temperatures and process conditions used in the scouring process associated with our invention will be essentially those well known in the art, for example those more fully described in U. K. Specification Nos. 812,894 and 916,338.

The invention is illustrated, but not limited, by reference to the following Example in which the percentages are by weight.

EXAMPLE

A plain woven grey cotton cloth weighing 5 ounces per square yard (air dry) containing approximately 100 percent of its own dry weight of trichloroethylene was treated with steam and/or water. The periods of treatment and the percentage residual trichloroethylene based on the dry weight of the cloth are shown below, in Table 1. --------------------------------------------------------------------------- TABLE 1

% Residual Method of Removal of Solvent Trichloroethylene Steam at 100.degree. C. for 3 sec. 0.54 Steam at 100.degree. C. for 6 sec. 0.28 Steam at 100.degree. C. for 9 sec. 0.15 Steam at 100.degree. C. for 12 sec. 0.15 Water at 95.degree. C. for 5 sec. 0.62 Water at 95.degree. C. for 8 sec. 0.47 Water at 95.degree. C. for 12 sec. 0.32 Water at 95.degree. C. for 20 sec. 0.16 Water at 95.degree. C. for 30 sec. 0.17 Steam at 100.degree. C. for 3 sec. followed by water at 95.degree. C. for 5 sec. 0.31 Steam at 100.degree. C. for 3 sec. followed by water at 95.degree. C. for 8 sec. 0.16 Steam at 100.degree. C. for 3 sec. followed by water at 95.degree. C. for 12 sec. 0.13 Steam at 100.degree. C. for 3 sec. followed by water at 95.degree. C. for 20 sec. 0.082 Steam at 100.degree. C. for 6 sec. followed by water at 95.degree. C. for 5 sec. 0.17 Steam at 100.degree. C. for 6 sec. followed by water at 95.degree. C. for 8 sec. 0.084 Steam at 100.degree. C. for 6 sec. followed by water at 95.degree. C. for 12 sec. 0.070 Steam at 100.degree. C. for 6 sec. followed by water at 95.degree. C. for 20 sec. 0.039 __________________________________________________________________________

Claims

What we claim is:

1. A process for removing an organic halogenated hydrocarbon textile cleaning solvent from a textile material which steps consist essentially of passing the textile material first through a steam chamber for a period of between 2 and 8 seconds and thereafter through a hot water bath for a period of between 5 and 20 seconds whereby the said solvent is removed from the textile material during the treatment with steam and during the treatment with hot water.

2. A process as claimed in claim 1 wherein the organic solvent is a chlorinated hydrocarbon solvent.

3. A process as claimed in claim 2, wherein the chlorinated hydrocarbon solvent is trichloroethylene, perchloroethylene, 1,1,2-trichloro-1,2,2-trifluoroethane or mixtures thereof.

4. A process as claimed in claim 1 wherein the textile material is a woven cloth.

5. A process as claimed in claim 1 wherein a major proportion of the organic solvent is removed by the treatment with steam and a minor proportion of the organic solvent is removed by the treatment with hot water.

6. A process as claimed in claim 5, wherein more than 90 percent by weight of the organic solvent is removed from the textile material during the treatment with steam.

7. A process as claimed in claim 1, wherein the period of the steam treatment is between 3 and 6 seconds.

8. A process as claimed in claim 1, wherein the period of the treatment in the hot water is between 8 and 15 seconds.