Effect of Aluminum Sulfate Treatments on Sizing Behavior of Handsheets Prepared by Internal Addition of Diperfluoroalkylphosphate

When diperfluoroalkylphosphate (DPFP) was used as a wet-end additive of papermaking, sizing efficiency was low, compared with the conventional internal sizes. Then, improvement of sizing performance by using aluminum sulfate was attempted for the DPFP-treated handsheets. However, sizing degrees of the handsheets remarkably decreased, when aluminum sulfate was used in place of polyamideamine-epichlorohydrin resin (PAE). Moreover, DPFP components once adsorbed on pulp fibers through aluminum components in pulp slurries were easily detached by extended stirring time of the pulp slurries. Meanwhile, when aluminum sulfate was added to pulp slurries in the cylinder of handsheet machine before drainage, where PAE and DPFP were added beforehand to the pulp slurries by the standard method, clear sizing improvement was observed for the handsheets prepared with 0.5% Al2(SO4)3. Positive effects of aluminum sulfate were also observed in soaking treatments of DPFP-treated base handsheets in a 0.5% Al2(SO4)3 solution.