关键词: 季铵盐, 阳离子改性剂, 栀子黄, 改性棉织物, 染色

Abstract:  To improve the dyeing performance of gardenia yellow on cellulose fibers, we designed and synthesized a series of cellulose fiber cationic modifiers with 3-chloro-2-hydroxypropyl as the active group and quaternary ammonium cation as the cationic group. Then, we introduced quaternary ammonium groups into cellulose fibers by nucleophilic addition reaction, and then dyed the fibers with gardenia dyes to improve the dyeing performance of gardenia yellow dyes.
The molecular structures of quaternary ammonium modifiers with different alkyl chain lengths were characterized by ESI-MS and proton nuclear magnetic resonance. FT-IR and X-ray photoelectron spectroscopy confirmed that quaternary ammonium compounds were successfully grafted onto the cotton fabrics through ether bonds. HPLC-MS was used to detect the binding mode between gardenia yellow dye and modified cotton fabrics.
The absorption peak of methyl bending vibration of quaternary ammonium compounds connected to nitrogen atoms on quaternary ammonium groups at 1,470 cm-1 was analyzed by Fourier infrared spectroscopy and the characteristic peak of binding energy of nitrogen elements at 399 eV was analyzed by X-ray photoelectron spectroscopy. It was confirmed that quaternary ammonium compounds were successfully grafted onto cotton fabrics in the form of ether bonds.
The cotton fabric was cationic treated with modifiers with different alkyl chain lengths, and the modified cotton fabric was dyed with gardenia yellow dye to compare the dyeing K/S values of the modified cotton fabric. The experimental results show that the optimal alkyl chain length of the modifier is 12, with a dye uptake rate of 85.46% and a K/S value of 4.33. This is because the growth of the alkyl chain of the modifier increases the positive charge on the surface of the fabric, enhancing the adsorption of dyes. But at the same time, the growth of the alkyl chain increases the molecular volume of the modifier, resulting in most of the modifier being grafted on the surface of the fiber, hindering the diffusion of dyes into the interior of the fiber. Therefore, when the alkyl chain is 18, the K/S value actually decreases.
The cotton fabric was modified with cationic modifier with the same concentration and different alkyl chain lengths, and the cotton fabric modified with quaternary ammonium cation with different alkyl chain lengths was dyed with gardenia yellow dye. And the effects of dyeing process conditions on K/S value, dyeing rate and color fastness of dyed fabrics were studied. The experimental results show that the dyeing performance of the fabric modified with CH-12 is the best, with a dyeing rate of 88.07% and a K/S value of 4.71.  At the same time, the cotton fabric modified with CH-12 has a soaping and rubbing fastness of over 3 levels, and a light fastness of 2‒3 levels.

Key words: quaternary ammonium salt, cationic modifier, gardenia yellow, modified cotton fabrics, dye