DYEING OF SILK WITH CATIONIC DYES

Abstract

Silk has an acidic, basic and hydrophobic groups, so that it may be dyeable by heat-transfer printing with cationic or disperse dyes.To obtain fundamental and theoretical information regarding dyes and dyeing conditions for silk or mixed yarn fabrics composed of silk and synthetic fibers, an attempt was made to investigate the dyeing of silk with cationic dyes.The conclusions obtained are summarized as follows: 1. According to the thermodynamical interpretation, the binding force of a cationic dye, C. I. Basic Red 18, to silk is smaller than that of a levelling dye, C. I. Acid Orange 7.2. Van der Waals and hydrophobic interactions, besides ionic one, seems to be operative in the adsorption of the cationic dye. 3. Dyeing rate is influenced greatly by pH of the dye bath, so that the pH values must be kept at constant values to obtain the stable and reproducible dyeing. 4. The fastness to sunlight was the highest with blue color dyes having anthraquinone chemical structure as compared to those having other chemical structures. Red color dyes except for an insulation type azo dye, C. I. Basic Red 18 do not show good fastness.Almost all yellow dyes examined show good fastness for the practical use. 5. In regard to the fastness to the washing, the fastness of the dyes to dry cleaning seems to be fast enough for practical use, but those to water or the washing are not sufficiently high as almost in the same level with that of levelling acid dyes.