Abstract
Handsheets were prepared from wood pulp and starch pulp in flake form with various wet-end additives, and basic properties of the handsheets were evaluated in terms of addition levels of the starch pulp. The starch pulp swollen in water by heating had a reinforcing effect on interfiber bonding between wood pulps in the handsheets, thus resulting in increases in tensile strength and folding endurance of the handsheets. Especially, the addition of the swollen starch pulp brought about a remarkable increase in folding endurance. Furthermore, the addition of polyamideamine-epichlorohydrin resin (PAE), one of the wet-strength resins, together with the swollen starch pulp had a synergistic effect on the increase in folding endurance. Although wet strength of the handsheets decreased by the addition of the starch pulp, high levels of wet strength were retained by the PAE addition. On the other hand, printing opacity and sizing degrees decreased with the starch pulp addition. However, size contents in the handsheets containing starch pulp were constant irrespective of the starch pulp additions, thus indicated that the presence of the starch pulp components in the handsheets led to the decrease in sizing degrees.
