Method and apparatus for dyeing cellulosic textile substrates with a leuco-state dye

Abstract

An apparatus for dyeing a cellulosic textile substrate with reduced indigo dye in a leuco-state in an inert atmosphere substantially isolated from oxidizing substances. A plurality of applicator faces that each apply a portion of the total dye application. The first foam applicator is spaced from the entrance of the chamber to allow air entrapped in the interstices of the substrate to escape. The applicators are spaced from each other to allow collapse of the foam and dispersion of the dye applied in the previous applicator before the substrate reaches the next applicator. Similarly, the exit is spaced from the last applicator to allow the foam to collapse and the dye to disperse prior to exiting the apparatus and entering the atmosphere in which oxidization of the dye occurs.

Description

[0001] This application is a continuation-in-part of pending U.S. patent application Ser. No. 10 / 833,450, filed Apr. 28, 2004.BACKGROUND OF THE INVENTION [0002] The present invention relates to an apparatus for dyeing cellulosic textile substrates with an inert leuco-state dye. More particularly, the present invention relates to an apparatus for dyeing cellulosic textile substrates with a reduced leuco-state dye foamed with an inert gas and applied in the leuco foamed state in an inert atmosphere to the textile substrate and subsequently oxidized thereon to affix the indigo dye to the cellulosic textile substrate. [0003] Dyeing cellulosic textile material, such as cotton yarn or fabric, with a leuco-state dye, such as indigo dye, has a large market, particularly for cotton denim clothing items, such as blue jeans. The fastness of the indigo dye on cotton and the deep color or shade that can be obtained make indigo dyed fabric a very popular product. However, dyeing cellulosic textil...

AI Technical Summary

Benefits of technology

[0007] Briefly described, the present invention provides an apparatus for dyeing cellulosic textile substrates with a foamed reduced leuco-state dye. The apparatus includes a housing having an interior chamber sealed from atmospheric air and through which the substrate travels from an entrance having a seal through which the substrate enters the chamber to an exit having a seal through which the substrate exits the chamber. A supply of inert gas communicates with the chamber to provide an inert environment therein. At least one foam applicator has an applicator face in said chamber and extending across the width of the substrate for applying foam containing the dye in leuco-state to the substrate in the chamber. A foam generator generates foam containing the leuco-state dye in the absence of oxygen with the generator communicating with the applicator for supplying the foamed leuco-state dye to the applicator. Thus, oxidation occurs primarily only after the substrate exits the chamber. However, there may be a minimal amount of oxygen in the otherwise inert gas and some small controlled amount of oxygen may purposely be included in the inert gas for desired controlled partial oxidization of the dye before it exits the chamber. Preferably, the supply of inert gas is under pressure to provide a pressurized inert environment in the chamber and minimize the entry of any atmospheric air through the entrance and exit. Also, preferably, the at least one applicator is spaced from the entrance to provide a free reach of the substrate in which air trapped in the interstices of the substrate is allowed to escape, and the at least one applicator is spaced from the exit to allow foam on the substrate to collapse and deposit and distribute the leuco-state dye on the substrate before the substrate exits the chamber and the dye is oxidized.

[0009] In the preferred embodiment, the inert gas is nitrogen and the foam generator generates a foam of nitrogen containing the leuco-state dye. One advantage of nitrogen being in the foam is that when the foam collapses in the chamber, the nitrogen increases the amount of inert nitrogen in the chamber environment.

Problems solved by technology

However, dyeing cellulosic textile material with indigo dye is a complicated, complex and expensive procedure, because indigo in its natural state will not affix to cellulosic fibers.

A significant problem with prior art indigo dyeing ranges is that of waste dye and water disposal.

This creates an undesirable substantial expense and environmental problem.

Therefore, there is no control of the condition of the substrate as it approaches and passes under the applicator and no control of the oxidation of the dye after it is applied to the substrate.

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