GB744461A - Improvements relating to process and apparatus for dyeing textile or other webs involving passage through a molten metal bath - Google Patents

Abstract

<PICT:0744461/IV(c)/1> <PICT:0744461/IV(c)/2> The process and apparatus of the parent Specification, as applied to the dyeing of cloth, webs, strips, warps or the like, wherein the cloth is passed first through a bath of dyeing or dye-developing liquor and then through a bath of molten metal, the dyeing liquor or dye-developing liquor, e.g. sodium hydrosulphite, floating as a layer on the surface of the molten metal, is modified in that (a) the liquor is fed to the layer at substantially the same rate as it is absorbed by the cloth and is heated just prior to its entry to the layer, the heating being applied to the liquor once only without recirculation of the liquor back to the heater; (b) the level of the layer actuates a modulating valve for controlling the flow of liquor to the layer; and (c) the layer is maintained of uniform composition by circulating the liquor out of and into the layer through a circuit positioned on the discharge side of the heater. As shown, Fig. 1, dyeing liquor from one of the reservoir tanks 1 is withdrawn through a filter 3 and fed by a pump 2 through a heater 10 to the dyebath 15, which comprises a layer of the liquor floating on the surface of a molten metal bath 16. The cloth to be dyed is passed through the dyebath, then through the molten metal bath and out through a Glauber salt bath 46, which also floats on the molten metal surface. The flow of liquor to the dyebath is controlled by a modulating valve 25 which is actuated through a float valve 28 by a change in level of the dyebath liquor. The heater 10 may be electrically, gas, oil or steam heated and, in the case of steam, the supply is controlled by a valve 19 which is actuated by a controller 20 responsive to a thermostat 24. Liquor is fed to dyebath 15 (Fig. 2) through a main conduit 14, a pair of branch conduits 30, 31 and a further pair of branch conduits 32, 33 which discharge into opposite sides of and into the ends of the dyebath, the liquor being distributed through gallery pipes 34 having slots designed to discharge the liquor in a direction parallel to the cloth. To ensure constant composition, the liquor is withdrawn from the ends of and returned to the middle of the dyebath by a pump 36, baffles being provided to deflect the incoming liquor in a direction parallel to the cloth. Specification 681,983 also is referred to.