硫酸铝添加对瓦楞纸表面施胶的影响规律及机理探讨

目的探讨表面施胶淀粉中添加硫酸铝对瓦楞纸强度性能和抗水性能的影响规律及机理,为更好地在表面施胶过程中合理应用硫酸铝,进而改善纸张性能提供理论支持。方法先通过实验考察硫酸铝对淀粉胶液pH值、粘度,以及纸张强度和抗水性能的影响,再通过对淀粉胶膜进行DSC检测和SEM观测,探讨硫酸铝影响纸张施胶的机理。结果硫酸铝的添加会显著降低淀粉胶液的pH值和粘度;在一定用量范围内,添加硫酸铝可明显改善纸张强度,且其最佳质量分数为6%;纸张抗水性能随硫酸铝含量的增加呈先增加后降低的趋势,其最佳质量分数在3%左右;添加硫酸铝的淀粉膜表面覆盖有一层纳米级的硫酸铝结晶,且玻璃化温度比原淀粉膜高。结论淀粉膜表面纳米硫酸铝结晶层的存在以及其玻璃化转变温度的升高会影响纸张表面施胶效果,是改善其强度性能的重要原因。

Influence Law and Mechanism of Al2(SO4)3 on Surface Sizing of Corrugated Paper

The paper aims to discuss the effects and the mechanism of the application of Al2(SO4)3 on strength and water resistance of corrugated paper in surface sizing process to provide theoretical support for better application of Al2(SO4)3 and improvement of paper performance. The effect of Al2(SO4)3 on the pH value and viscosity of starch paste and on the strength and water resistance of paper were firstly investigated through experiments. Then the mechanism of Al2(SO4)3 affecting paper sizing was discussed by DSC and SEM observation for starch film. Addition of Al2(SO4)3 can significantly reduce the pH value and viscosity of starch paste; in a certain range of dosage, the strength of paper could be significantly improved by the addition of Al2(SO4)3, the optimal dosage was about 6% (mass fraction); the water resistance of the paper would firstly be increased and then decreased with the adding of Al2(SO4)3, and the optimal dosage was about 3% (mass fraction); a layer of nano-crystallizations was found on the surface of starch film containing Al2(SO4)3 by SEM observation; DSC detection also showed that the glass transition temperature of the starch film was significantly improved by the adding of Al2(SO4)3. The nano Al2(SO4)3 crystallizations layer on the surface of starch film and the increase of its glass transition temperature are both the important reasons for the Al2(SO4)3 to affect the sizing effect of paper, especially the strength performance.