Lint reduction chemical performance is difficult to establish based Oil lab testing. A new lint test based oil specific handsheet-making conditions, poll tape and image analysis, which can produce the same magnitude of linting and porosity than actual mill sheets, was developed. Two mills experiencing severe lint problems were selected to evaluate several lint-control products with the proposed test method. Results indicate that a new surfactant-based additive was more effective than conventional lint-control chemicals.

A research program has been conducted to optimize the removal of suspended solid, anionic components and dissolved materials from deinking mill effluent, specifically the alkaline wastewater loop. The chemical characteristics of the additives investigated were the molecular weight of anionic and cationic flocculants, their charge density variations and the molecular structure of the chemical components. Polyaluminum chloride (PAC) in high dosage showed enhanced dissolved solid removal efficiency, however, the chitosan biopolymer and the bioenzyme explored in this study were not effective. The optimized chemical combination is apparently not cost effective in the present state-of-art DAF process.

Prediction of the response of pulp to different retention and drainage systems in the laboratory is a difficult task. Over the years there have been many attempts to develop a relevant laboratory retention/drainage device aimed at simulating the papermaking process. However, these devices do not exactly match paper machine's retention and drainage since it is very difficult to simulate a real furnish composition in the laboratory. We have developed a methodology to overcome this by recirculating white water during furnish preparation. A drainage device was also developed to simulate water removal by vacuum allowing prediction of the response of the furnish to drainage on the paper machine. This study showed that furnish preparation using white water recirculation is essential to properly simulate papermaking conditions and can be used to evaluate various retention and drainage programs performances in the laboratory.

In a previous study, we have shown structured (branched and cross-linked) cationic polyacrylamides (C-PAM) improved retention and drainage over a traditional linear C-PAM in fine paper manufacturing. The improvement wwas more significant at highturbulence. This study presents the effect of the same structured polymers on sheet formation. Results show that the structured and linear C-PAM provides similar formation. In addition, structured C-PAM dosages required to obtain a specific retention level decrease with increasing turbulence while that of the linear C-PAM must be increased.

Zeolites are framework aluminosilicates that have been proposed as a replacement for bentonite in microparticle retention systems. It has been claimed in many patents that zeolite can improve sheet formation in fine paper manufacturing. However, this improvement was not observed in mechanical grades. These experimental results, and also theoretical evidence, suggest that papermaking pH plays an important role in zeolite efficiency. In consequence, the effect of pH and temperature on the chemical properties of zeolite and bentonite microparticles was determined. Streaming potential, conductivity, and pH were measured while microparticle solutions were gradually acidified to pH 5. Samples were also taken at specific pH values to measure the cationic demand. Results showed that a gradual reduction of pH caused several modifications to zeolites. The first step was the neutralization of free hydroxyl ions in solution. The second step was an irreversible exchange of the charge-compensating sodium ions by hydrogen ions on the inner and outer surface of microparticles. Finally, dealumination of the zeolites occurred. It was determined that neutralization must be completed before ion-exchange can begin. However, ion-exchange and dealumination occurred simultaneously. Between pH 7.5 and 9, zeolites had more anionic sites than bentonite (around 0.8 meq/g vs. 0.5 meq/g). The higher surface charge of zeolites might partly explain their efficiency in microparticle systems. On the other hand, under pH 7.5, the anionic charge of zeolite samples rapidly decreased while that of bentonite was stable. The effect of temperature was also studied in the 25 to 55 °C range. Generally, a temperature rise promoted a greater dissociation of the surface hydroxyl groups and an acceleration of ion-exchange and dealumination processes.