US3653801A

US3653801A - Pad-acid steam nylon-cotton blend with acid and vat dyes

Info

Publication number: US3653801A
Application number: US664028A
Authority: US
Inventors: Ibrahim Ahmed Aboul-Saad
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1967-08-29
Filing date: 1967-08-29
Publication date: 1972-04-04
Anticipated expiration: 1989-04-04

Abstract

A process for dyeing nylon/cotton textile fabrics which comprises: 1. CO-APPLYING THE VAT AND ACID DYES AT A PH of 4-8, 2. STEAMING THE FABRIC IN THE PRESENCE OF A VOLATILE ORGANIC ACID, 3. DRYING THE FABRIC, AND 4. FIXATING THE VAT DYE IN A CONVENTIONAL MANNER, HAS BEEN FOUND TO GIVE A UNION SHADE IN A CONTINUOUS MANNER WITH GOOD UTILIZATION OF THE DYE APPLIED.

Description

[451 Apr. 4, 1972 PAD-ACID STEAM NYLON-COTTON BLEND WITH ACID AND VAT DYES [72] Inventor: Ibrahim Ahmed Aboul-Saad, Wilmington,

Del.

[73] Assignee: E. l. du Pont de Nemours and Company,

Wilmington, Del.

[22] Filed: Aug. 29, 1967 [211 App]. No.: 664,028

[52] U.S. Cl. ..8/21 B, 8/34, 8/178 R [51] lnt.Cl. ..D06p 3/82 [58] Fleld of Search ..8/24, 34, 178, 21 B [56] References Cited UNITED STATES PATENTS 3,503,698 3/1970 Zurbuchen et al ..8/41 3,467,485 12/1969 Schaeuble ..8/54 3,137,687 6/1964 Spoerri .260/160 2,447,993 8/1948 Vieira ,.8/34 3,240,553 3/1966 Paul ..8/l00 OTHER PUBLICATIONS Dyeing & Finishing Dupont Nylon Bulletin N- 194, Dec. 1965 Ward ..8/24

Primary Examiner-Donald Levy Attorney-Howard P. West, Jr.

[57] ABSTRACT A process for dyeing nylon/cotton textile fabrics which comprises:

l. co-applying the vat and acid dyes at a pH of 4-8,

2. steaming the fabric in the presence of a volatile organic acid,

3. drying the fabric, and

8 Claims, 1 Drawing Figure DRY PAD-ACID STEAM NYLON-COTTON BLEND WITH ACID AND VAT DYES FIELD OF THE INVENTION This invention relates to an improved continuous process for dyeing nylon/cotton textile fabrics with acid and vat color to a union shade by a modified pad-steam process.

STATE OF THE ART A process for applying vat dyes to textile fibers by pigment pad process wherein the goods can be continuously padded and developed without extra handling and without any chance of surface oxidation of the color of fiber prior to complete development of color, has been described by Vieria in US. Pat. No. 2,447,993. This process is frequently referred to as the pad-steam process, and is preferred to the pad-jig process because it limits the migration of dye from one fiber to another. In nylon and cotton-containing fabrics having greater than 25 percent by weight of the fiber as nylon, the pad-steam process does not dye the nylon and cotton fibers to the same depth of shade. Most vat dyes, under these circumstances, produce a darker shade on cotton than on nylon. Such a shade differential produces an effect known as frosting" when the darker dyed cotton fibers wear away leaving a higher concentration of nylon fibers of a lighter shade on the surface of the fabric. In order to overcome such difficulties, it has been suggested that the additional application of acid dyes be used in order to produce an acceptable uniformity of shade on both the nylon and cotton fibers. Either the application of acid dyes on a pad-steam range followed by vat dyes or the application of vat dyes followed by acid dyes have been suggested. However, both procedures require two processing steps which reduce the savings that can be made in processing large quantitles of fabrics by continuous process. In order to retain the economy of a one-pass continuous dyeing process, a recent development reported in the March, 1967 Textile Industries has been suggested which incorporates the co-application vat, and acid, or neutral dyeing premetallized dyes as used in the two-stage processes in a one-pass system, which schematically is described as pad acid plus vat dyes/infrared dry/Thermosol/pad reducing agent/steam/wash/dry. Such a process has limited application to provide adequate coloration for fabrics which do not require a union color between the nylon and cotton fibers. It is unsatisfactory for fabrics containing more than 25 percent nylon by weight of fibers unless excessive amounts of acid dye are utilized in order to overcome the incomplete development of the acid dye used.

OBJECT It is the object of this invention to provide a process for dyeing nylon and cotton fabrics to a union shade in a continuous manner with good utilization of the dye applied. It is a further object to provide a process for dyeing piece goods in a continuous manner, which can be employed in applying colors in heavy shades in a single operation.

STATEMENT OF THE INVENTION These objects are accomplished by the present invention which provides an improvement in the continuous process for union dyeing nylon/cotton fabrics which comprises the steps of:

l. co-applying the vat and acid dyes at a pH of 4-8;

2. steaming the fabric in the presence of a volatile organic acid, such as acetic acid;

3. drying the fabric;

4. fixating the vat dye in a conventional manner.

The fixation of the vat dye is conventionally done by (1) padding reducing agents on the dyed fabric followed by (2) steaming, (3) washing and (4) oxidizing. The fabric may then optionally be rinsed, soaped, rinsed and dried to remove any excess of the oxidizing solution or foreign matter followed by a final drying step.

DRAWING A more complete understanding of the process of this invention can be obtained by reference to the drawing which forms a part of this specification and which contains a diagrammatical representation of how the nylon and cotton fabrics may be dyed and developed in a continuous manner by this process.

As diagrammatically illustrated in the drawing, the cotton/nylon fabric is (l) padded with the vat and acid dyes, (2) steamedin the presence of an organic acid, (3) dried, (4) optionally heated to a temperature greater than 400 l'-'., (5) padded with a reducing agent solution, (6) steamed, (7) washed and (8) dried thereby oxidizing the vat dye.

While not wishing to be held to this explanation, it is believed that the critical step in the continuous process of this invention is the utilization of the acid-steaming step. In this step the nylon/cotton fabric is steamed for 3060 seconds at a temperature between 230-250 F. in the presence of a volatile organic acid such as acetic acid. The volatile organic acid may be present from previous preparatory steps used on the fabric or may be present as a result of the pH adjustment made during the application of the dyes. In some cases it may be desirable to add or inject the volatile organic acid into the steamer. Any organic acid capable of volatilizing at the temperature encountered in the steaming step is suitable. It is believed that the selected acid dyes transfer from the cotton to the nylon and dye the nylon at this time. The vat pigment which is also present is partially agglomerated within the fabric, thus, minimizing the tendency to migrate to the fabric surface during the subsequent drying steps and, therefore, readily available for uniformly dyeing the cotton fiber throughout the fabric thickness. After drying the steamed fabric, it may be desireable to expose the fabric to a temperature of about 400 F. (204 C.) to 430 F. (222 C.) for at least 60 seconds in order to improve the acid dye utility.

It is also possible to reduce the degree of migration of the vat dyes during the steaming and drying stages by the addition of salt, such as sodium chloride, or the like, which tends to form weakly bonded agglomerates of vat pigments, thereby reducing migration. If desired, a high padding pressure may be utilized to fracture the vat dye agglomerates to allow their penetration into the fabric.

The following examples are given to illustrate the invention. Unless otherwise specified the parts used are by weight.

The efficiency of acid dye utility is estimated by microscopic examination of the dyed polyamide fiber. The color change produced by abrasion of the dyed fabric is rated on a scale of l to 5 based on the Gray Scale for Evaluating Change in Color described in the AATCC Technical Manual, 1966, page B-57.

EXAMPLE I Sodium hydrocarbon sulfonate, 7.5 grams per liter of a refined solution of natural gums, and 1 gram per liter formic acid is padded at 150 F. (65 C.) on a 35 percent polyamide and 65 percent cotton fabric with the padder set for 50 percent moisture retention based on the weight of fabric. Without drying the padded-fabric is passed through a steaming chamber for a 60 second exposure. The fabric is immediately passed to a dryer operating at 300 F. (149 C.) for a 60 second exposure. The fabric is then immediately padded with a reducing agent consisting of grams per liter of caustic soda and 100 grams per liter of sodium hydrosulfite and again steamed for 60 seconds before rinsing. The impregnated fabric is then oxidized in the conventional manner in a 0.25 percent chromeacetic acid solution, rinsed, soaped, rinsed, and dried. The fabric is dyed a dark green shade with good penetration and fastness to laundering and abrasion. The acid dye utility is rated as 50-80 percent and the abrasion color change is rated as 4-5 on the Gray Scale.

EXAMPLE I! The fabric of Example I is padded with a dye mixture containing 50 grams per liter of Vat Green 3 (Color Index No. 69500), grams per liter of Vat Green 1 (Color Index No. 59825), 10 grams per liter of Anthraquinone Blue GSS (Color Index No. Acid Blue 230), 10 grams per liter of Merpacyl Orange R (Color Index No. Acid Orange 128), 2 grams per liter of Sodium hydrocarbon sulfonate, 7.5 grams per liter of a refined solution of natural gums, and 1 gram per liter formic acid. The pad mixture is applied at 150 F. (65 C.) and the fabric immediately steamed at 230 F. (110 C.) for 45 seconds before drying at 250 F. (121 C.) for 90 seconds before padding on the fabric a reducing agent containing a 90 g/l caustic soda and 90 g/l sodium hydrosulfite. The fabric is then steamed at 230 F. (110 C.) for 45 seconds followed by rinsing, oxidizing, soaping, rinsing, and drying as in Example I. The fabric is uniformly dyed throughout the fabric thickness to a dark green shade with good fastness to laundering and abrasion resistance. The acid dye utility is rated as 50-80 percent and the color change is rated as 4-5 on the Gray Scale.

EXAMPLE Ill The following example illustrates the best one-path continuous dyeing process that can be obtained from the prior art but without the steaming step. The polyamide and cotton fibers are not uniformly dyed to the same even shade. A dye mixture containing 18 grams per liter Vat Green 8 (Color Index No. 69500), 25 grams per liter Vat Black 25 (Color Index No. 69525), 3.8 grams per liter Vat Blue (Color Index No. 59800), 11.25 grams per liter of Acid Green (Color Index No. 61570), 7.5 grams per liter of Capracyl Orange R (Color Index No. Acid Orange 60), 7.5 grams per liter of Sodium hydrocarbon sulfonate, and 15 grams per liter of a refined solution of natural gums is added on the same fabric as used in Example I at 120 F. (49 C.) and immediately predried over gas-fired burners and then dried on 16 heated cans. The fabric is immediately heated at 430 F. (221 C.) for 3 minutes followed by padding of a reducing agent containing 90 g/l caustic soda and 90 g/l sodium hydrosulfite. Fabric is then steamed for 35 seconds at 225 F. (107 C.) followed by oxidizing, rinsing, soaping, rinsing, and drying as in previous example. Inspection of the fabric shows that the cotton fibers are dyed to a darker shade than the polyamide fibers and is not fast to laundering. The color change from abrasion is rated as 2-3 on the Gray Scale and the acid dye utility is rated as 10-20 percent.

It will be understood that various changes in the invention may be made without departing from the spirit and scope thereof, and therefore this invention is not intended to be limited except as indicated in the appended claims.

What is claimed is: g

l. A process for union dyeing of nylon/cotton fabric which comprises the successive steps of l. co-applying vat and acid dyes at a pH of 4 to 8,

2. steaming the said fabric in the presence of a volatile organic acid,

3. drying the said fabric, and

4. fixating the said vat dye, said fixating step comprising the conventional steps of padding reducing agents on the dyed fabric followed by steaming, washing and oxidizing the fabric.

2. Claim 1 wherein said organic acid is acetic acid.

3. Claim 1 wherein said organic acid is formic acid.

4. Claim 1 wherein said drying is accomplished by exposing the said fabric to a temperature of about 400 F. to about 430 F. for at least 60 seconds to improve acid dye utility.

5. Claim 1 wherein said drying is accomplished by exposing the said fabric to a temperature of about 250 F. to about 300 F. for from about 60 to about seconds.

6. Claim 5 wherein said organic acid is formic acid.

7. Claim 6 wherein said vat dye is fixated by padding the said fabric with a reducing agent consisting of about grams per liter of caustic soda and 100 rams per-liter of sodium hydrosulfite, steaming the said fa ric, rinsing the said fabric and oxidizing the said vat dye.

8. Claim 7 wherein said oxidizing is accomplished by contacting the said fabric with a 0.25 percent chrome-acetic acid solution and said fabric is subsequently rinsed, soaped, rinsed and dried.

Claims

1. CO-APPLYING THE VAT AND ACID DYES AT A PH OF 4-8,

2. STEAMING THE FABRIC IN THE PRESENCE OF A VOLATILE ORGANIC ACID,

2. Claim 1 wherein said organic acid is acetic acid.

2. steaming the said fabric in the presence of a volatile organic acid,

3. drying the said fabric, and

3. Claim 1 wherein said organic acid is formic acid.

3. DRYING THE FABRIC, AND

4. FIXATING THE VAT DYE IN A CONVENTIONAL MANNER, HAS BEEN FOUND TO GIVE A UNION SHADE IN A CONTINOUS MANNER WITH GOOD UTILIZATION OF THE DYE APPLIED.

4. Claim 1 wherein said drying is accomplished by exposing the said fabric to a temperature of about 400* F. to about 430* F. for at least 60 seconds to improve acid dye utility.

5. Claim 1 wherein said drying is accomplished by exposing the said fabric to a temperature of about 250* F. to about 300* F. for from about 60 to about 90 seconds.

6. Claim 5 wherein said organic acid is formic acid.

7. Claim 6 wherein said vat dye is fixated by padding the said fabric with a reducing agent consisting of about 100 grams per liter of caustic soda and 100 grams per liter of sodium hydrosulfite, steaming the said fabric, rinsing the said fabric and oxidizing the said vat dye.