US3716325A - Dyeing cotton or regenerated cellulose using sulfur dyes oxidized with aqueous sodium bromite solution - Google Patents

Abstract

Method for dyeing cotton or regenerated cellulose textile fibers with sulfur dyes, comprising the steps of applying at least one sulfur dye in reduced (leuco) form to said fibers and subsequently oxidizing said dye by contacting it with an oxidizing solution comprising water and sodium bromite and having pH 7-12.

Description

United States Patent Aspland 1 Feb. 13, 1973 [54] DYEING COTTON 0 REGENERATED 1,905,346 4/1933 Dreyfus et al. ..8/64 Fryer et al. OXIDIZED WITH AQUEOUS SODIUM OTHER PUBLICATIONS BROMITE SOLUTION John Richard Aspland, Charlotte, NC.

Inventor:

Martin Marietta Corporation, New York, N.Y.

Filed; Jan. 25, 1971 Appl. No.: 109,593

Assignee:

US. Cl. ..8/37, 8/82, 8/51,

8/] Q, 8/] XA Int. Cl. ..C09b 49/00, D06p 1/30 Field of Search ..8/37, 82, l 0,64

References Cited UNITED STATES PATENTS 10/1949 Mayhew ..8/37 X Knecht et al., Principles & Practice of Text. Print., 1952, p. 589-590 Primary Examiner-George F. Lesmes Assistant Examiner-Patricia C. Ives At!0rney lohn A. Crowley, Jr., Francis J. Mulligan, Jr. and Wilton Rankin [57] ABSTRACT 2 Claims, No Drawings DYEING COTTON OR REGENERATED CELLULOSE USING SULFUR DYES OXIDIZED WITH AQUEOUS SODIUM BROMTTE SOLUTION The present invention relates to a method for dyeing, and more particularly to a method for dyeing textile fibers with sulfur dyes.

Generally speaking the present invention may be defined as in the method for dyeing cotton or regenerated cellulose textile fibers with sulfur dyes, comprising the steps of applying at least one sulfur dye in reduced (leuco) form to said fibers and subsequently oxidizing said dye by contacting it with an aqueous solution of an oxidizing agent, the improvement characterized in that said aqueous solution of an oxidizing agent comprises water and sodium bromite and has pH 7-12.

As used herein, the term sulfur dyes means those dyes which may be applied in a reduced (leuco) state to cotton fibers from solutions containing sodium sulfide, or sodium hydrosulfide, or sodium polysulfide, and which dyes have affinity for cotton, and which dyes may be subsequently oxidized on the fibers, and which dyes contain divalent sulfur in the form of thiol or alkali metal thiolate when in their reduced state.

A number of oxidizing agents have been suggested for reduced sulfur dyes, but few are used on a large scale in commercial practice.

The most popular oxidizing agent for reduced sulfur dyes is sodium bichromate mixed with acetic acid (called chrome and acid). Another popular oxidizing agent for reduced sulfur dyes is hydrogen peroxide. Aqueous sodium chlorite has also been employed to a small degree in commercial practice as an oxidizing agent for reduced sulfur dyes. However, all of these prior art usages have disadvantages and limitations, some of which will be described below. Certain of such disadvantages and limitations have, surprisingly, been overcome by the method of the present invention.

The primary disadvantage of chrome and acid concerns stream pollution. Water pollution control authorities in some areas have already set strict limits on the liquid waste effluent from chrome and acid dyeing which will be permitted to enter streams. To avoid very expensive effluent treatment systems, those in charge of a number of textile finishing plants are actively seeking alternate oxidation systems. Relatively harmless effluent, largely dilute aqueous sodium bromide, results from the method of the present invention.

After reduced sulfur dye has been oxidized on cotton or regenerated cellulose yarn, it is difficult to remove residual chrome and acid by washing, and it is customary to soap the yarn at the boil during such washing. In the process of the present invention, soaping at the boil and excessive washing after oxidation are unnecessary, as the residues resulting from the oxidation are water soluble salts. By avoiding soaping at the boil, one source of yarn weight loss during dyeing is eliminated and processing cost is reduced.

The acid in chrome and acid causes undesirable liberation of H 8 during the oxidation step, and residual acid accelerates tendering of cotton on ageing, while acid is not used in the oxidation step of the present process, which is conducted under neutral or alkaline conditions.

The degree of wash fastness of cotton and regenerated cellulose dyeings made from sulfur dyes depends upon the particular sulfur dye employed and upon the oxidizing agent employed. Wash fastness of such dyeings is considerably less when hydrogen peroxide is used as the oxidant than when chrome and acid is used as the oxidant. The wash fastness of dyeings made by the process of the present invention varies from acceptable to very good, depending upon the particular sulfur dye employed. Generally speaking, the wash fastness of dyeings made by the process of the present invention is about the same as the wash fastness of dyeings resulting from hydrogen peroxide oxidation.

Hydrogen peroxide has the following three major disadvantages as an oxidizing agent for reduced sulfur dyes used on cotton and regenerated cellulose textile fibers. Wash fastness of such dyeings is considerably less than when chrome and acid is used as the oxidant; not all sulfur dyes, disadvantageously, such as those sulfur dyes made by sulfurizing 4-hydroxydiphenylamine,

can be fully oxidized to stable shades with hydrogen peroxide; and concentration of the peroxide in the oxidizing bath is both critical to the fastness properties of the resulting dyeing and troublesome to control, requiring frequent measurement of peroxide concentration With many sulfur dyes on cotton or regenerated textile fibers, chrome and acid oxidation results in dyeings having a harsh hand. This causes excessive wearing of needles and fiber fracture during sewing and knitting, and necessitates use of lubricants during yarn and raw stock dyeing to soften the harsh yarn. Cotton and regenerated cellulose textile fibers dyed by the present process with sulfur dyes have a surprisingly soft hand, thereby eliminating necessity for use of the lubricant.

Cotton and regenerated cellulose textile fibers dyed with sulfur dyes, wherein chrome and acid has been used as the oxidant, are not easily rewettable, which necessitates use of wetting agents in any subsequent wet finishing operation, while fibers dyed by the present process are easily rewettable in subsequent wet finishing operations, without the aid of wetting agents.

either by time consuming titrations or by use of an expensive machine for measuring optical density and hence hydrogen peroxide concentration in the ultra violet region of the spectrum. In contrast, all sulfur dyes can be oxidized to stable shades by the process of the present invention, even those made by sulfurizing 4-hydroxydiphenylamine. Generally speaking, and depending upon the particular sulfur dyes selected, the shades produced by sodium bromite oxidation indicate that the state of oxidation is either equal to that produced by chrome and acid oxidation, or that the state of oxidation is equal to or higher than that produced by hydrogen peroxide. All reduced sulfur dyes are oxidized sufficiently with sodium bromite to produce adequately oxidized and desirable dyeings.

The primary disadvantage of aqueous sodium chlorite as an oxidizing agent for leuco sulfur dyes applied to cotton and regenerated cellulose textiles is that sodium chlorite simply will not oxidize many sulfur dyes to a commercially acceptable state, under conditions recommended for sodium chlorite, which are the same conditions recommended for sodium bromite herein. Some sulfur dyes bleed very badly after being oxidized with sodium chlorite, or perhaps more precisely after being partially oxidized. Based on the dyeings which I have made with aqueous sodium chlorite, it is my opinion that aqueous sodium chlorite is little, if any, superior to plain water as an oxidizing agent for reduced sulfur dyes on cotton and regenerated cellulose textile fibers. lndophenol sulfurized vat dyes, red-brown sulfur dyes made from sulfurization of 4-hydroxydiphenylamine, and certain orange, blue and green sulfur dyes are not oxidized to a commercially acceptable state by aqueous sodium chlorite.

The following is a more detailed description of the present invention, and all parts herein are by weight unless otherwise specified.

The cotton and regenerated cellulose textile fibers which may be dyed according to the process of the present invention may be in any desired form, such as knitted or woven fabric, yarn, ball warps, non-woven fabric or raw stock.

The reduced (leuco) sulfur dye may be applied to the fibers in any desired manner, such as by jig, pad, beck, roller, or package machine.

lf-desired the fibers having the dye thereon may optionally be batched for a period of time, steamed or dried to facilitate penetration of the dye into the fibers.

The fibers having the reduced sulfur dyestuff thereon are then contacted with the aqueous oxidizing solution to fix the dyestuff, such as by immersing the fibers in the oxidizing solution.

The neutral or alkaline aqueous oxidizing solution comprises water and sodium bromite, and has pH 7-12, and preferably pH9-l0. It will be understood by those familiar with bromite chemistry that at pH 7-9 small amounts of sodium hypobromite will customarily be found in the aqueous sodium bromite. As aqueous sodium bromite solution is neutral, it will be understood that small amounts of alkali, such as NaOH or Na,CO will be present in aqueous sodium bromite solutions more alkaline than pH 7.0. Accordingly, the aqueous oxidizing solution contains about -2 percent alkali, depending upon its pH and upon the alkali selected. Enough sodium bromite should be employed to oxidize the dyestuff. in continuous dyeing on padding equipment it is suggested that the concentration of aqueous sodium bromite in the pad box be maintained at 0.05-0.4 percent by weight, and preferably at about 0.1 percent by weight. In batch dyeing, it is suggested that the concentration of sodium bromite be about 0.1 percent of the dry weight of the goods being dyed. The aqueous oxidizing solution may also contain 0-30 percent of a simple electrolyte, such as NaCl, Na SO or MgSO, to inhibit bleeding of dyestuff into the oxidizing solution. Use of the simple electrolytes is unnecessary in continuous pad dyeing, but may be advantageous in some batch dyeing processes. If desired, the oxidizing bath may contain other conventional additives such as non-ionic or anionic surface active agent, e.g., a fiber wetting agent. Excessive amounts of sodium bromite may decrease wash fastness of the dyeing. If the oxidizing solution is to be stored for several days, it is suggested that it be stabilized by raising the alkalinity to pH 10 or above with an alkali such as NaOH.

Accordingly, the aqueous solution of sodium bromite used in continuous pad dyeing by the process of the present invention may comprise, by weight, 0.05-0.4

percent sodium bromite, 030% NaCl, Na SO or Mg- SO,, O-2 percent alkali, 67.6-99.95 percent water, and have pH 7-12. In batch dyeing, the concentration of sodium bromite will be less.

The oxidizing solution may be at ambient temperature to 160 F. when it contacts the leuco dyestuff. Aqueous sodium bromite at ambient temperature readily oxidizes sulfur dyes, but the oxidation rate increases with temperature increase. Oxidation proceeds very rapidly in continuous dyeing, and is essentially complete when the dyestuff and aqueous sodium bromite have been in contact about 30 seconds, based on 0.1 percent sodium bromite concentration at ambient temperature. In batch dyeing, the fabric having thereon dyestuff will customarily remain in the 0.1 percent by weight of goods aqueous sodium bromite about 10-15 minutes to achieve the desired oxidation.

After oxidation of the dyestuff, the fibers may be washed and dried in conventional manner.

The following are illustrative examples of embodiments of the present invention, in which all parts and percentages are by weight unless otherwise specified. References in the examples to C. 1. names and numbers for sulfur dyes are to COLOUR INDEX, Second Edition, Supplement 1963, published by The Society of Dyers and Colourists, Yorkshire, England.

EXAMPLE 1 A dye solution is made by reducing 1 oz. copper tetra-(4)-thiocyanophthalocyanine (U.S. Pat. No. 2,342,662) with aqueous Na S and diluting to 1 gallon with water. To woven cotton shirting weighing 4 oz/sq. yard is applied, by padding, the dye solution at F., whereafter the fabric is squeezed to permit 60 percent wet-pick-up based on fabric weight. The fabric is steamed at 230 F. for 1 minute; passed through three wash boxes containing water and equipped with nip rollers; immersed for 30 seconds in an aqueous oxidizing solution at room temperature containing 0.1 percent sodium bromite and adjusted to pH 10 with NaOH; rinsed by passing through 3 wash boxes containing warm water; and dried. A brilliant green dyeing results.

When 0.1 percent sodium chlorite is substituted for the 0.1 percent sodium bromite used in Example 1, a dull greyish-green dyeing results.

EXAMPLE 2 This example is the same as Example 1 above, except that a dye solution consisting of 20 oz. SODYESUL Liquid Black 4GCF (20 percent aqueous prereduced C. l. Leuco Sulfur Black 1, C. I. No. 53185) per gallon of water is substituted for the dye used in Example 1.

A black dyeing very similar to that obtained with chrome and acid oxidation, except having better rewettability, results. When sodium chlorite is substituted for sodium bromite in the process of Example 2, a yellower and duller dyeing than the Example 2 dyeing results.

EXAMPLE 3 This example is the same as Example 1 above, except that 1 oz. C. I. Sulphur Brown 52 powder (C. I. No. 53320), calculated as pure dye, is substituted for the copper tetra-(4)-thiocyanophthalocyanine used in Example l, and except that the sodium bromite solution is at 160 F. The resulting dyeing is reddish orange.

When sodium chlorite is substituted for the sodium bromite used in Example 3, the resulting dyeing is dull brick red.

EXAMPLE 4 This example is the same as Example 1 above, except that 1 oz. C. l. Sulphur Red powder (C. I. No. 53228), calculated as pure dye, is substituted for the copper tetra-(4)-thiocyanophthalocyanine used in-Example l, and except the concentration of sodium bromite is increased from 0.1 to 0.4 percent. The resulting dyeing is a fully developed red-brown dyeing.

When sodium chlorite is substituted for the sodium bromite used in Example 1, there is insufficient color development on the resulting dyeing, and the resulting dyeing bleeds considerably on washing.

EXAMPLE 5 This example is the same as Example 1 above, except that 1 oz. C. l. Sulphur Blue 13 powder (C. I. No. 53450), calculated as pure dye, is substituted for the copper tetra-(4)-thiocyanophthalocyanine used in Example l, and except that the sodium bromite solution is adjusted to pH 12 with NaOH.

A bright blue dyeing results. The resulting dyeing is brighter than those obtained with chrome and acid oxidation, but slightly inferior in wash fastness to chrome and acid dyeing.

lf sodium chlorite is substituted for the sodium bromite used in the Example 5 dyeing, the resulting blue dyeing is not fully developed.

EXAMPLE 6 This example is the same as Example 1 above, except that oz. 6 percent aqueous pre-reduced C. l. Leuco Sulphur Green 2 dye (C. I. No. 53571) per gallon of water is substituted for the dye solution used in Example 1; except that NaOH is omitted from the sodium bromite solution, which has pH 7; except that regenerated cellulose rayon fabric weighing 3 oz./sq. yard is substituted for the cotton fabric; and except that the temperature of the sodium bromite solution is increased to F.

A green dyeing results.

EXAMPLE 7 This example is the same as Example 1 above, except that 1 oz. C. I. Sulphur Brown I dye powder (C. I. No. 53000), calculated as pure dye, is substituted for the copper tetra-(4)-thiocyanophthalocyanine used in Example l; except that the sodium bromite concentration is reduced to 0.05 percent; and except that woven regenerated cellulose rayon fabric weighing 3 oz./sq. yard is substituted for the cotton fabric used in Example l.

A chocolate brown dyeing results, similar in shade to that obtained from chrome and acid oxidation but with slightly inferior wash fastness thereto.

What is claimed is:

1. In the method for dyeing cotton or regenerated cellulose textile fibers with sulfur dyes, comprising the stepspf applying at least one sulfur dye in reduced form to said ti ers and subsequently oxi izing said dye by Notice of Adverse Decision in Interference In Interference No. 98,460, involving Patent No. 3,716,325, J. R. Aspland, DYEING COTTON OR REGENERATED CELLULOSE USING SUL- F UR DYES OXIDIZED WITH AQUEOUS SODIUM BROMITE SOLU- TION, final judgment adverses to the patentee was rendered June 29, 1976, as

to claims 1 and 2.

[Ofii'cz'al Gazette November 30, 1.976.]

Claims (1)

1. In the method for dyeing cotton or regenerated cellulose textile fibers with sulfur dyes, comprising the steps of applying at least one sulfur dye in reduced form to said fibers and subsequently oxidizing said dye by contacting it with an aqueous solution of an oxidizing agent, the improvement wherein said aqueous solution of an oxidizing agent comprises, by weight, 0.05-0.4 percent sodium bromite, 0-30% NaCl, Na2SO4, or MgSO4, 0-2 percent alkali, and 67.6-99.95 percent water, and has pH 7-12.