Improvement Of Paper Strength By Partially Aminated Polyvinylformamides

The preparation and properties of vinylformamide-based cationic polymers, as well as their applications as paper strength additives, were investigated in this paper. Aminated poly-N-vinylformamides (APNVFs) were synthesized by partially hydrolyzing polymerized NVF with concentrated HCl at different dosage, and they were used as papermaking additives to improve paper strength. The results indicated that the polymers had a significant effect on paper strength. The factors affecting the properties of polymer such as molecular weight, charge density, and additive dosage were discussed in detail. The results showed that both the dry strength and the wet strength of paper sheets were greatly enhanced by the addition of APNVFs. When the addition level of polymer APNVF was reached at 0.5% based on dried Pulp, the dry strength of paper was improved by 38% and the wet strength was as 3.5 times as that of the control. Among the partially aminated poly-N-vinylformamides (APNVFs), the APNVF with low to intermediate charge density was the most efficient for paper dry strength while the APNVF with high molecular weight and high charge density was the most effective for paper wet strength. The significant effectiveness of the polymers as additives for paper dry and wet strength was achieved, especially for the improvement of paper wet strength.