Sequential Oxidative/Reductive Bleaching and Dyeing of Wool in a Single Bath at Low Temperatures

Abstract

A new bleaching and dyeing process applicable to wool involves a sequential oxidative/reductive bleaching combined with a subsequent dyeing in a single bath. Apart from dyebath bleaching processes in which the bleaching agent is added towards the end of the dyeing process when almost all the dye is exhausted, bleaching and subsequent dyeing are normally done in separate baths due to the sensitivity of the dyes to bleaching agents. In the latter process, it is important that all bleaching agents be thoroughly washed off before dyeing, because any residual bleaching agent (hydrogen peroxide, reductive bleach) may adversely affect the results. The newly developed single-bath process begins with an oxidative hydrogen peroxide bleaching followed by addition of thiourea to the residual hydrogen peroxide in the same bath. Thiourea dioxide formed by the resulting chemical reaction hydrolyzes in solution to sulfonate anion and urea. Sulfinate anion is a strong reducing agent and effects reductive bleaching. At the end of the reductive bleaching stage, a small amount of hydrogen peroxide is added to oxidize all the reductive sulfur species in solution to the sulfate anion, which together with the urea serves subsequently as a dye assist. Once the temperature of the bath is lowered, dyes may be added to the same bath. The new sequential single-bath bleaching/dyeing process results in much brighter pastel shades upon dyeing, due to better whiteness obtained initially with sequential oxidative/reductive bleaching. Furthermore, there is a reduction in processing time, temperature, and effluent compared with conventional procedures and the utilization of byproducts from the initial bleaching assists during the subsequent dyeing step.

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References

1. Arifoglu

Marmer

W. N.

Carr

C. M.

, Sequential Oxidative and Reductive Bleaching of Wool in a Single Bath, Textile Res. J. 60 (6), 319–328 (1990); Arifoglu, M., and Marmer, W. N., Sequential Oxidative and Reductive Bleaching in a Multicomponent Single Liquor System, U.S. patent 4,961,752, October 9, 1990, and U.S. patent application 07/552,381 (notification of allowability October 31, 1990); and Arifoglu, M., and Marmer, W. N., Sequential Oxidative and Reductive Bleaching and Dyeing in a Multicomponent Single Liquor System, U.S. patent application 07/697,549 (May 9, 1991).

2. Arsov

Kunchev

Serafimov

, Single Bath Bleaching and Dyeing of Wool by Acid Azo Dyes, Tekst. Prom. Sofia 19 (10), 29–32 (1970); Chem. Abst. 75 (4), 22318k.

3.ASTM, Breaking Load and Elongation of Textile Fabrics, 1981 Book of ASTM standards, 361–369, American Society for Testing and Materials, Philadelphia, ASTM D-1682–64.

4.BASF A.G., technical leaflet M5756e, 1981.

5. Bendak

, Low-temperature Dyeing of Protein and Polyamide Fibres Using a Redox System, Dyes Pigments 11 (3), 233–242 (1989).

6. Bird

C. L.

, Theory of Wool Dyeing, in “The Theory and Practice of Wool Dyeing,” 4th ed., The Society of Dyers and Colourists, Bradford, Great Britain, 1972, pp. 38–40.

7.Ciba-Geigy Co., Simultaneous Dyeing and Bleaching Fibres, Swiss patent 6314624, November 29, 1963.

8. Duffield

P. A.

, Dyeing for Machine Washable Fabrics, in “Proc. Wool in the Eighties Seminar,” Wakefield, MA, 1984, pp. 173–174.

9. Duffield

P. A.

, Review of Wool Bleaching, IWS technical information bulletin, 31–33, 1986.

10.

10. Garber

, Practical Application of Lanaset dyes, in “Proc. Wool in the Nineties Technical Seminar,” Plymouth, MA, 1990, pp. 75–78.

11.

11. Lemin

D. R.

Vickerstaff

, Some Physicochemical Properties of Damaged Wools, J. Soc. Dyers Colour. 62, 129–144 (1946).

12.

12. Lewis

D. M.

, Dyeing and Wet Processing of Wool, in “Proc. 8th Int. Wool Textile Res. Conf., Christchurch, New Zealand,” vol. IV, 1990, pp. 1–49.

13.

13. Maclaren

J. A.

Milligan

, Sulfitolysis and Oxidative Sulfitolysis, ch. 3 in “The Chemical Reactivity of Wool Fibre,” Science Press, Marrickville, New South Wales, Australia, 1981.

14.

14. Mosimann

, Optimized Dyeing Systems for Wool Yielding High Production, Quality and Economy, in “Proc. Wool in the Nineties Technical Seminar,” Plymouth, MA, April 1990, pp. 18–33.

15.

15. Nikolova

Arsov

Kunchev

Medyalkova

, Single Bath Dyeing and Bleaching of Mixed Wool-Artificial Fibre Yarn, Tekst. Prom. Sofia 21 (4), 193–196 (1972); Chem. Abst. 81 (14), 79197y.

16.

16. Rippon

J. A.

Harrigan

F. J.

, Dyeing Wool at Low Temperature—A New Approach, in “Proc. 8th Int. Wool Textile Res. Conf., Christchurch, New Zealand,” vol. IV, 1990, pp. 50–59.

17.

17. Schmidt

, Simultaneous Dyeing and Bleaching of Proteinaceous Fibrous Material, U.S. patent 3551087, December 29, 1970.

18.

18. Schmidt

, Simultaneous Dyeing and Bleaching of Wool, German patent 1469609, January 26, 1970.

19.

19. Schmidt

, Procedure to Bleach and to Dye Protein-containing Fibres in a Single Bath, Belgian patent 672398, May 16, 1966.

20.

20. Schumacher-Hamedat

Fohles

Zahn

, Oxidation Intermediates of Cystine During Bleaching Processes, in “Proc. 7th Inter. Wool Textile Res. Conf., Tokyo, Japan,” vol. IV, 1985, pp. 120–129.

21.

21. Senner

Ulmer

Renner

, Possibilities of Single Bath Dyeing and Bleaching of Wool, Z. Gesamte Textilind. 68 (10), 763–767 and (11), 858–863 (1966).

22.

22. Uehara

, Dyeing and Bleaching of Fibers, Japanese patent 73 20,975, March 15, 1973.

23.

23. Uehara

, Single Bath Bleaching and Dyeing of Textiles, Japanese patent 73 61,782, August 29, 1973.