Novel Dyeing Method for Polypropylene Fiber via Reduction and Oxidation Processes of Cationic Dye

ポリプロピレン(PP)は汎用樹脂の中で比重が最も 小さく,耐熱性,剛性に優れ,また透明性,耐水性, 耐薬品性,絶縁性が良好である.これらの優れた特性 から PP は自動車,フィルム,シート,雑貨,家電, 医療機器,繊維など様々な分野で利用されている. 特に,PP 繊維が開発された当初はその有用性から 夢の繊維とまで言われ,様々な応用が期待された.し かしながら,現在,繊維としての主な用途は,アンダー ウェア,カーペット,ロープ,ビジネスソックス,産 業資材等に限られ,アパレル分野での利用は少なく未 だ夢は夢のままである[1]. このアパレル分野における PP 繊維の利用の少なさ は,PP 繊維の染色性の悪さに起因するところが大き い[2].つまり,PP 繊維はその単純な分子構造のた めに染着座席をまったく持たず,染色性に乏しいこと から,ファッション性の高い服地への利用は難しいの である. それゆえに,この様々な有用性を持ちながらも,染 色性に乏しい PP 繊維をアパレル分野で利用するため の染色研究は,世界中で 50 年以上実施されている. 例えば,樹脂の製造時に顔料を混練する方法(原着), PP 繊維に染色可能な部材や官能基を導入する方法 [3],超臨界流体を用いて染料を繊維内部に浸透させ る方法[4],繊維の表面を電子線で改質する方法[5] などである.しかしながら,原着では色の種類の不足, 染色可能な部材の導入では物性の変化による PP の良 Abstract: Polypropylene (PP) fibers have various excellent characteristics. However, it is difficult to use PP fibers for fashionable apparels due to its poor dyeing properties. Hence, in this paper, it has studied that developing a novel simple and inexpensive dyeing method for PP fibers by utilizing a cationic dye. It was developed that the PP dyeing method with the reduced form of a cationic dye, namely, leuco form. In the method, the permeability and affinity of the cationic dye for PP fibers would have been enhanced by reducing the cationic dye treated with a reducing agent in the alkaline aqueous solution. As a result, the reduced form of the cationic dye was adsorbed onto the PP fibers. Although, the color of the dye disappeared under an alkaline condition, the adsorbed cationic dye was recolored and fixed by treating with an oxidizing agent, and the dyed PP fibers were obtained. Following aforesaid method, the dyed PP fabrics were obtained by reducing the cationic dye with glucose under an alkaline condition at 100 ̊C and oxidizing it in an aqueous acetic acid solution at 50 ̊C. It was found that the L* of the dyed fabrics were low when Basic Blue 3, Basic Red 2, Basic Yellow 7, and Basic Orange 14 were used as a cationic dye. (Received 17 November, 2019; Accepted 1 April, 2020)