Reactive dyes have now been available for 25 years and have proved to impart important technological advantages to the wool dyer. This explanatory paper outlines the initial development of these dyes, emphasizing the special problems encountered in applying them to wool, summarizes present developments and future trends, critically appraises the performance of reactive dyes for wool vis-a-vis alternative dyes, and considers the large amount of research work carried out to pinpoint the particular amino acid site(s) involved in the reaction of wool with reactive dyes.

The Dyeing of Wool with Reactive Dyes

The dye-fibre bond stabilities of various bifunctional dyes (commercially known as Sumifix Supra dyes) have been investigated by measuring the kinetics of dye-cotton bond hydrolysis in aqueous buffer solution at 98dC. The stabilities are generally found to be somewhat higher than those of comparable monofunctional reactive dyes. Significantly better, however, is the fixation yield of the bifunctional dyes. Reasons for a very low uptake of a non-commercial bromamine acid-based bifunctional dye are discussed.

Dye‐fibre bond stabilities of dyeings of bifunctional reactive dyes containing a monochlorotriazine and a ß‐hydroxyethylsulphone sulphuric acid ester group

Dye–fibre bond stabilities of some reactive dyes on cotton

57th Communication on Investigations in Textile Chemistry, for 56th Communication see ref. J.



Silk was dyed with twelve reactive dyes containing various reactive groups. The dyeings were thoroughly extracted so that all non-covalently bonded dye was removed. The extracted dyeings were treated with buffer solutions in the pH range 1.89 to 10.65 at 70°C for 24 h. The exhaustion, fixation ratio and extent of reaction of the dyeings and the rate of hydrolysis of all dyed samples in six buffers were measured. The dye-fibre bond was found to be sufficiently resistant to hydrolysis for ail dyeings. The fixation ratio and wet fastness were particularly good for dyeings with α-bromoacrylamide groups and with difluorochloropyrimidine groups.

Dye‐Fibre Bond Stabilities of Some Reactive Dyes on Silk

Several fibre–reactive basic (polymethine) dyes containing the N–chloroacetyl group have been prepared. They had better washing fastness on wool than their non–reactive analogues.



Exhaustion figures were obtained in the usual way (colorimetrically) for all the dyes in Table 1 at the following pH: 2. 5, 3. 6, 4. 7, 5. 8, 6. 9 and 8. 4. However, these results were not in accord with visual assessments of the depths and it appears likely that some decomposition of the dyes takes place, in the presence of wool, particularly at higher pH values.

Fibre–reactive Basic Dyes I–Polymethine Dyes Containing the N–Chloroacetyl Group

Wool was dyed with seven reactive dyes having the same chromophoric group (1-amino-4-anilino-anthraquinone-2- sulfonic acid) but different reactive groups and then thoroughly extracted so that all noncovalently bound dye was re moved. The wool was treated with buffer solutions in the pH range of 1.6-10.6 at 70°C. The hydrolysis rate of the dye-fiber bonds was estimated by colorimetric measurement of the buffer solution.Reactive dyes containing the α-bromoacrylamide or the difluoromonochloropyrimidyl system gave the highest fixation on wool, whereas those containing a mono- or di-chloro-s-triazine, trichloropyrimidine, or vinylsulfone group gave lower values. Poor fixation was obtained with the β-hydroxyethylsulfone sulfuric acid ester and the β-hydroxyethylsulfona mide reactive group. Since only 2-10% dye-fiber bond hydrolysis was observed after 24 hr at 70°C, it must be concluded that the dye-fiber bond stability of all the reactive groups now available is sufficient for wool dyeing. The washfastness of ...

J.F.K. Wilshire

Papers

Dye-Fiber Bond Stabilities of Some Reactive Dyes with Wool