磷酸酯型两性淀粉结构性能及其对纸张的增强作用

Study on Structural Characteristics of Phosphate Amphoteric Starch and Its Reinforcing Effect on Paper

以木薯原淀粉、3-氯-2-羟丙基三甲基氯化铵和混合磷酸盐为主要原料,用半干法工艺合成了磷酸酯型两性淀粉,用FT-IR、XRD、SEM等对产物结构性能进行了表征;研究了其作为纸张增强剂对废纸浆的增强作用。结果表明,改性剂与木薯原淀粉反应不仅发生在无定形区,而且发生在结晶区;不仅发生在颗粒的表面,也可进入其内部;在一定条件下,产物的阳离子取代度随着磷酸盐用量的增加而减小,阴离子取代度随淀粉阳离子取代度的提高而降低。实验合成的磷酸酯型两性淀粉对纸张的增强作用显著,当添加量为1.0%(对绝干浆)时,纸张的抗张指数、耐破指数和撕裂指数分别比空白样提高了23.5%、20.3%、29.4%。

In the paper, the phosphate amphoteric starch was synthesized by using cassava starch 3-Chloro-2-hydroxypropyl-trimethylammonium Chloride （CTA） and mix-phosphate as raw materials and by semi-dry process in two steps. The structure properties were characterized and analyzed by FTIR, XRD and SEM. The reinforcing effect of the amphoteric starch on wastepaper pulp was studied. The results indicated that the reaction between the modifier and starch occurred not only on the surface but also in the interior of starch granule, not only in amorphous region, but also in crystalline region. When the cationic starch reacted with different amount of phosphates, the degree of cation substitution （DSC） of the product decreased with increasing the dosage of phosphates; the degree of anion substitution （DSA） of the products decreased with the increase of DSC. Among nine samples synthesized in this study, the No.7 sample （DSC=0.067, DSA=0.028） synthesized in this study had better reinforcing effect on paper strength. Compared with the control sample, tensile index, tear index, and burst index were increased by 23.5%, 20.3% and 29.4% respectively, when its dosage was 1.0% （based on oven dry pulp）.