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 combination of aluminum sulfate and an α-hydroxy acid has proven highly effective in catalyzing the crosslinking of cotton cellulose by glyoxal under mild curing conditions. The durable press a...

Glyoxal as a Formaldehyde-Free Durable Press Reagent for Mild Curing Applications':

Glyoxal was found to impart a high degree of wrinkle resistance and smooth drying qualities to all-cotton printcloth. Certain aluminum salts were effective catalysts, the least fabric discoloration being produced with aluminum sulfate. Addition of ethylene glycol or glycerol to the treating solutions eliminated almost all of the discoloration and increased the durable-press appearance ratings. Evidence is presented that the catalytic activity of aluminum sulfate is not explainable on the basis of generation of sulfuric acid by partial hydrolysis of the aluminum salt, and that metal ion catalysis, as well as specific catalysis by hydrogen ions, may take place in the case of glyoxal crosslinking of cellulose. Unlike formaldehyde, glyoxal monomer, dimers, and trimers have structures favorable for chelation by polyvalent metal ions, and such complexes may play a part in the crosslinking reactions. At ordinary concentrations of glyoxal, the durable-press treatments produced very large strength losses in the fa...

Glyoxal as a Non-Nitrogenous Formaldehyde-Free Durable-Press Reagent for Cotton'

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

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 ...

Dye-Fiber Bond Stabilities of Some Reactive Dyes with Wool

Nine metal chlorides and mixtures of these salts with tartaric acid are compared with hydrochloric acid with regard to catalytic activity in crosslinking cotton fabrics with formaldehyde by the pad-dry-cure process. The sequence of catalytic activity can be rationalized by the hard/soft concept of acids and bases. When highly active catalysts are applied, the relation between dry crease-recovery angle and tensile strength is significantly improved for DMEU-cross-linked fabrics but only marginally improved when formaldehyde is used as the crosslinker.

Comparison of Catalytic Activities and Textile Mechanical Properties Observed in the Crosslinking of Cotton with Highly Active Catalysts

A statistical evaluation of percentages of methylated sorbitols, found by the permethylation-degradation method of cellulose formulas, demonstrates that the percentage of 6-monomethylsorbitol results essentially from intraglucosic bridges formed by two (or more) oxymethylene groups between the hydroxyl groups in the 2- and 3-positions of an anhydroglucose unit of cellulose.

H.K. Rouette

Papers

Dye-Fiber Bond Stabilities of Some Reactive Dyes with Wool

Comparison of Catalytic Activities and Textile Mechanical Properties Observed in the Crosslinking of Cotton with Highly Active Catalysts

A Method for the Detection of Intraglucosic Crosslinks in Cellulose Formals