改性纳米纤维素材料对纸张涂布的影响及作用机制

Utilization of nanofibrillated cellulose in paper coating is considered a potential field in modern papermaking industry. However, the nanofibrillated cellulose is tending to self-assemble due to its high specific surface area and large amounts of hydroxyl groups. The introduction of strong anionic or cationic groups onto the cellulose fibers could improve the dispersity and stability of the nanofibrillated cellulose solution, but its relative poor dispersity at high concentration and poor interface property with the latex limit its application in industry scale. The styrene and butadiene monomers could be easily grafted onto the nanofibrillated cellulose, the steric hinerance of the grafted hydrophobic groups with long chains gives the nanofibrillated cellulose a better dispersity and stability, and the interface property with the latex could be improved as well. The grafted nanofibrillated cellulose with different structures could be obtained by controlling the grafting degree and the monomer ratio; its effects and mechanism on the coating and coating paper could be characterized as the grafted nanofibrillated cellulose were applied in paper coating.

纳米纤维素用于纸张涂布被认为是最具工业化应用前景的技术。但纳米纤维素比表面积大且带有大量的羟基，在较高的浓度和较长的储存时间内下极易发生絮聚从而影响其使用效果。通过化学改性的方法在纳米纤维素表面引入强阴/阳电荷基团（通过电荷斥力）可改善其分散性和稳定性，但在较高的浓度下稳定性仍存在不足，且由于其表面大量亲水性基团于涂料中胶乳的相容性较差，仍无法满足在涂布工业中的应用要求。在纳米纤维素近均相体系中接枝苯乙烯和丁二烯单体，引入疏水性大分子的空间位阻效应可进一步改善其分散性和稳定性，同时改善其在涂料中与胶乳的界面相容性。通过控制NFC-g-St-Bu的接枝率及单体比例组成，可以制备出不同结构的NFC-g-St-Bu。将其使用在涂布纸生产，可以准确表征出NFC-g-St-Bu结构特征对涂料及涂布纸性能的影响及影响机制，为改性纳米纤维素在涂布纸加工中的应用提供理论依据。