US2074031A - Continuous dyeing process - Google Patents

Description

March 1937- J. H. STRADLEY CONTINUOUS DYEING PROCESS Filed May 11, 1935 INVENTOR. I: JHStrac/l? Patented Mar. 16, 1937 v UNITED STATES CONTINUOUS DYEING PROCESS James H. Stradley, Carneys Point, N. J., assignor to E. I. du Pont de Nemours & Company, Wilv mington, Del., a corporation of Delaware Application May 11, 1935, Serial No. 21,017

2 Claims.

This invention relates to dyeing. More par-m ticularly the invention relates to a continuous method of dyeing. The invention has particular application to the dyeing of materials such as 5 yarn or fabric which are in considerable lengths, and will be described in relation to the dyeing of a roll of cotton cloth. It is to be understood, however, that this particular description does not limit the invention beyond the scope of the appended claims.

There has been described in prior art a method which involves dyeing a roll of cotton coth with an azo dyestufi containing a free amino group, diazotizing the dyestufi" on the dyed cloth and coupling to it, while still on the fiber, an azo dyestufi coupling component. In that process, the first dyeing is carried out on a jigger, the essentials of which include a tank, a roller at each side and one at the bottom of the tank. The cloth is wound on one roller, passed under the roller in the tank, and attached to the other roller; the tank is filled with dye solution, the cloth is drawn back and forth through the dye bath, the temperature is raised almost to boiling, and the material is given four to six additional passages through the solution. When the desired shade has been obtained the tank is drained, filled" with cold water, and the material rinsed by repeated passages through the water.

0 The rinsing bath is drained off, the tank is filled with a diazotizing bath heated to 60-70" F., the cloth is twice passed through the bath, the machine is drained and filled with fresh water, and the cloth is again rinsed. The tank is once more drained, is filled with a coupling bath containing an azo dyestufi' coupling component, and the cloth is given two passages at 60-70 F. to form the final dye. The tank is emptied, filled with fresh water, the material is passed through until it is ing of the undyed fiber is carried out by a single passage through the dyestuif solution.

Attempts have heretofore been made to dye by,

this method continuously: A number of tanks have been alined and the cloth has been passed through them in succession. Thus, in one meth- 0d the original 'dyestuff was applied by padding,

and the diazotization and development wereaccomplished by passing the cloth through the alined tanks containing a concentrated diazotizing bath heated to. -70 F a rinsing bath, a concentrated developer bath, and as many rinses 5 and soapings as was advantageous. The cloth was dried by passage over heated rollers.

The value of the method described in the preceding paragraph was limited because it was necessary for the cloth to remain in contact with 10 the diazotizing and developing agents for the period ,of time required forflthe slowest bath to operate, which in almost all cases proved excessive; because the use of very concentrated diazotizing and developing baths reduced the time of 15 immersion but entailed an inability to properly expose the material; and because the variation in the rate of development of different dyes, and in the, shades obtained, limited the process to use with a very few dyestufis. j 20 Comparing the methods of the prior art, efiective diazotization was carried out in the intermittent method at low concentrations and low temperatures, temperatures above F. being undesirable. A typical bath contained per 25 gallons of water 1.5 pounds of sodium nitrite, 2.5-3.0 pounds of sulfuric acid (66 B.) or 1.87-2.25 pounds hydrochloric acid (20 B.), and the temperature would be held at 60-70 The diazotization bath or the continuous process of 30 the prior art contained, per each 100 gallons of water, 12 pounds of sodium nitrite, 9.4 pounds of sulfuric acid (66 B.) or 21 pounds hydrochloric acid (20 B.), and was held at a temperature of 60'70 F. The coupling bath of the 5 intermittent prior art process contained (using beta naphthol in illustration), per 100 gallons of water, 0.5 pounds of betanaphthol, and 0.5 pounds of caustic soda at a temperature of 60-70F. The continuous prior art process contained per 100 0 gallons of water, 33.0 pounds of beta naphthol and 16.5 pounds of caustic soda.

It is an object of the invention to dye materials by a continuous methodwhich is equally applicable to all dyestuffs substantive to cotton and 45 regenerated cellulose and having a diazotizable ally through diazotizingsand' coupling baths main- -55 5 inafter described.

The process is illustrated in a preferred embodiment in the accompanying drawing, showing a diagrammatic representation of the dyeing of a roll of cloth, in which X is the roller holding the roll of cloth before applying the process; Y

is the winding roller upon which the processed cloth may be collected; R are rollers, all, some, or none of which may be driven. In the preferred form of the invention the rollers outside 15 the tanks will be driven and those within the tank will be freely mounted. Driers, not shown, may be located between tank G and roller Y.

On the roller X is wound dyed cloth of which the dyestuff has a free amino group. The tank A contains a diazotizing bath. In the preferred form of the invention that bath contains per gallons of water 2 to 3 pounds of sodium nitrite, 10 to 12 pounds of sulfuric acid (66 B.) or 8 to 10 pounds of hydrochloric acid (20 B.), and will be maintained at a temperature of 140 F. The tank B contains running cold water, but in some instances it can be replaced by a shower bath. The rollers R between tanks may, when it is advantageous, have complementary pressure rollers R to squeeze excess moisture out of the cloth; the moisture so expelled may be caught in a trough T and conducted away from the process or back to, the tank A. After the cold-water rinse in tank B, the cloth dyed with the diazotized dyestuif is drawn into tank C which contains a developing bath. The developer selected by the dyer will depend on the color and shade desired in the final dye. An exemplary bath contained '1 to 2 pounds of beta naphthol, and 1 /2 to 2 pounds of caustic soda per 100 gallons of water, heated at about 140 F. The other azo dyestufi coupling components may be used in place of the beta naphthol. For instance, 1 to 2 pounds of 1-phenyl-3-methyl-pyrazolone, or 1 to 1 pounds of 2:4-diamino-toluene produce similar results when used with 1 to 1 pounds of caustic soda. Other coupling components whose use is contemplated include: hydroxy aryls such as beta napththol and resorcinol; amino aryls such as 2:4-diamino-toluene, 1 :S-diamino-benzene, and ethyl-beta-naphthylamine; hydroxy aryl carboxylic acids such as beta-hydroxy-naphthoic acid and its amides; pyrazolones such as methylphenyl pyrazolone, amino-aryl-pyrazolone, and aryl-carboXy-pyrazolone; and aceto-acet arylids such as aceto-acet-anilide. Sulfonic acid derivatives of the above classes can be used, but in many cases they tend to solubilize the dye to an undesirable extent. This listing of coupling components is exemplary of classes not an exhaustive list of compounds.

Passing from tank C, the cloth with the newlydeveloped dyestufi is rinsed in cold water in tank D, soaped at -140 F. in box E which contains about three "pounds of soap to each 100 gallons of water, rinsed in warm water (about 120 F.) in box F, and in cold water (preferably running) in box G. The dyed and washed cloth may, if desired, be dried before winding on roller Y.

The temperature of F. is not an operative upper limit, satisfactory results being obtainable 75 upwardly thereof, but it is a temperature at which excellent efiiciency is obtained and above which the evolution of gases is excessive.

An advantage of the invention is a continuous process of dyeing useful with substantially all dyestuff substantive to cotton and regenerated cellulose and capable of diazotization and development on the fiber. This advantage is illustrated by reference to the following colors, identified by the Color Index Number, which could not be successfully used by the old continuous process, but produce entirely satisfactory results when applied by my process.

CI-297 Diazotized and developed with beta naphthol CI-317 Diazotized and developed with beta naphthol 01-322 Diazotized and developed with beta naphthol CI-323 Diazotized and developed with 2:4-diamino-toluene 01-324 Diazotized and developed with l-phenyl- B-methyl-pyrazolone CI-324a Diazotized and developed with beta naphthol CI-339 Diazotized and developed with beta naphthol CI-401 Diazotized and developed with 2:4-diamino-toluene CI-552 Diazotized and developed with 2:4-diamino-toluene CI-625 Diazotized and developed with betanaphthol CI-812 Diazotized and developed with naphthol Another advantage of the invention is in the saving of time and labor in dyeing. In the jigger method three to five hours were required to complete the dyeing process. The continuous process of the prior art, when used with those few colors which could be successfully applied, acted in about three minutes per bath. My invention operates on cotton or regenerated cellulose with any dyestuff of the class described and reduces the time to about ten seconds per bath. Another advantage of my process is that the concentration of 'diazotizing and developing baths is about equal to the prior intermittent process and far lower than those of prior continuous processes.

The use of alkaline coupling baths in the examples is not a limitation to baths of that type. The coupling bath will be made alkaline, neutral, or acid in accordance with the dictates of good practice relating to each particular coupling component.

The fastness to washing, and discharge properties of the dyestufis when produced by my new continuous method are equal to those of the old prolonged jigger process.

As many apparently widely diiferent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A continuous method of dyeing which comprises passing a material of the class consisting of cellulose and regenerated cellulose dyed with an azo dyestuif substantive to cotton or regenerated cellulose having a diazotizable amino group through a diazotizing bath heated to about 140 F. and a coupling bath containing an azo dyestuff coupling component, the material being betaimmersed in said diazotization bath for a period of time not greater than about ten seconds.

2. A continuous method of dyeing which comprises passing a material of the class consisting of cellulose and regenerated cellulose dyed with an azo dyestufi substantive to cotton or regenerated cellulose and having a diazotizable amino group, through a diazotizing bath heated to about 140 F., and a coupling bath containing an azo dyestufi coupling component selected from the group consisting of beta naphthol, 2:4-dlaminotoluene and 1-phenyl-3-methyl-pyrazolone, the material being immersed in said diazotization bath for a period of time not greater than about ten seconds.

- JAMES H. STRADLEY,

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