酚羟基对木质素磺酸钠染料分散剂性能的影响

Influence of Phenolic Hydroxyl Groups on the Performance of Lignosulfonate as a Dye Dispersant

木质素磺酸盐最大的用途之一是用作染料分散剂,但其对涤纶纤维存在较严重的沾污及对分散染料具有较强的还原水解作用,导致染料在纤维上的上染率降低。今以木质素磺酸钠为原料,利用环氧氯丙烷对其进行改性,研究了酚羟基对其结构特征和性能的影响。水相滴定法、紫外可见光谱和凝胶色谱等测试结果表明,随着环氧氯丙烷用量的增加,木质素磺酸钠中酚羟基含量减少,分子量逐渐增大,木质素磺酸钠的色度降低。随着木质素磺酸钠中酚羟基含量减少,其对纤维的沾污和对染料的还原水解率逐渐降低。频率-耗散联用型石英晶体微天平测试结果表明随着木质素磺酸钠中酚羟基含量减少,其在染料上的吸附量先减少后显著增加,吸附层先变疏松再变紧密,说明酚羟基的减少降低了氢键作用吸附,增强了疏水作用吸附,使其对分散染料的分散性能以及高温稳定性呈现出先降低后提高的趋势。木质素磺酸钠中酚羟基含量的减少和分子量的增加有利于提高染料在纤维上的上染率。

Lignosulfonate is widely used as a dye dispersant but with disadvantages including fiber staining and reduction of dye, which result in the decrease of dye uptake. In this paper, lignosulfonate was modified with epichlorohydrin to study the influence of phenolic hydroxyl groups on its structure and dye dispersion performance. Aqueous phase titration, UV spectroscopy and gel permeation chromatography results indicate that with the increase of epichlorohydrin, the phenolic hydroxyl content on lignosulfonate decreases, and the molecular weight of lignosulfonate increases and its color gradually turns light. The decrease of phenolic hydroxyl content can result in the decline of fiber staining and reduction degree. Quartz crystal microbalance with dissipation monitoring shows that with the decrease of phenolic hydroxyl content on lignosulfonate, its dye adsorption capacity decreases in the beginning and then significantly increases. The adsorption layer becomes loose first and then solid, which reflects that the decrease of hydrogen bonding eliminates the dispersant adsorption while the increase of hydrophobic interaction strengthens the adsorption. Consequently, the dispersibility and heat stability decrease first and then increase. In conclusion, the decrease of phenolic hydroxyl content and the increase of molecular weight are beneficial to improve dye uptake.