Behavior of chemically modified cellulose towards dyeing. IV. Dyeability of poly(methyl vinyl pyridine)-cellulose graft copolymers before and after treatment with epichlorohydrin



Grafting of 2-methyl-5-vinyl pyridine (MVP) onto partially carboxymethylated cotton having 6 meq COOH/100 g cellulose (PCMC) was effected by a Fe2+-H2O2 redox system. Different graft yields were obtained by varying MVP concentration from 10 to 100 wt % PCMC. In a subsequent step these graft copolymers were treated with epichlorohydrin. Dyeing of untreated cotton, PCMC, PCMC grafted with MVP, and epichlorohydrin-treated poly(MVP)-PCMC graft copolymers was carried out at room temperature (27°C) for varying lengths of time (2.5–60 min) in the absence of alkali catalyst or any other additives. Three reactive dyes, Procion Red M-GS, Procion Orange Brown H-2GS, and Remazole Brilliant Blue; a direct dye, Orangé Solophényle 2RL; and an acid dye, Erio Blue Marine 2GR were used at a concentration of 2% by weight of material. It was found that none of the three reactive dyes or the acid dye interacts with untreated cotton or PCMC. In contrast, the direct dye did. PCMC grafted with MVP, on the other hand, showed a substantial extent of dye exhaustion regardless of the dye used. After-treatment of poly(MVP)-PCMC graft copolymers with epichlorohydrin significantly enhanced the extent of dye exhaustion. The latter reacted almost 100% with all the dye examined, irrespective of the graft yield, which varied from 1.6% to 63%. Dyeings for reactive dyes withstood soaping for 1 hr at boil and extraction with 50% dimethylformamide, whereas dyeings for the direct dye and the acid dye failed to do so. It is believed that the presence of pyridine moieties in the graft act as an internal, built-in catalyst for expediting the reaction of reactive dyes with cellulose hydroxyls and behave as a weak base capable of salt-linkage formation in case of the acid and direct dyes.