Effective Lac Dyeing of Cotton Fabric by Pretreating with Tannic Acid and Aluminum Acetate
Transaction Effective Lac Dyeing of Cotton Fabric by Pretreating with Tannic Acid and Aluminum Acetate Yukiko Togo and Motoko Komaki Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan Abstract: Lac dyeing of cotton fabrics pretreated with tannic acid and aluminum acetate was investigated. Five treatment methods (tannic acid alone, aluminum alone, tannic acid → aluminum, aluminum → tannic acid, and tannic acid → aluminum → tannic acid) before dyeing with lac were compared for their effect on adsorption of the laccaic acid to cotton fabric. The treatment with tannic acid → aluminum was found to be the most effective for lac dyeing of cotton. It was found that tannic acid enhanced the aluminum adsorption to cotton fabric, and the affinity of aluminum to laccaic acid enhanced the dyeing effect. The adsorption of tannic acid, aluminum and laccaic acid to cotton was quantitatively determined, and the dyeing mechanism was proposed. (Received 11 November, 2009 ; Accepted 24 November, 2009) 1. Introduction pretreated with a cationic agent [3, 4], polyethyleneimine (PEI) [5] and chitosan [6, 7]. On the other hand, it was Lac color is a natural red dyestuff obtained from the proposed by an artist a method of pretreating cotton with resinous secretion, sticklac, from lac scale insects which tannic acid and aluminum acetate for dyeing with inhabit Southeast Asia. This sticklac adheres to the twigs cochineal which has the main component of carmic acid of trees, and contains a resin and colorant. This resin, of similar chemical structure to laccaic acid [8]. The shellac, is used for such purposes as varnish, a coating method described was treating the cotton fabric with agent for medical tablets and fruits, and a water-proof tannic acid solution beforehand, then with aluminum material.
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