Some properties of newsprint impregnated with polyvinylamine

We measured wet-strength and dry-strength properties of newsprint impregnated with polymers in the polyvinylamine familily. Polyvinylamine is a recently commercialized polymer with the potential to increase the tolerance of wood-containing papers to water-based printing processes. Poly(N-vinylformamide) (PNVF), the precursor to polyvinylamine (PVAm), increased dry strength but not wet strength. Both PVAm and partially converted PNVF-co-PAm copolymers increased both wet strength and dry strength dramatically. Over the range of 56% to 100% conversion of PNVF to PVAm, there was little difference in the wet strength of the resulting paper. The wet strength of PVAm-impregnated newsprint was a little higher at pH 10 than at lower pH values. Drying at 120°C gave only slightly higher wet strength than did drying at room temperature.