Lime mud CaCO₃ for use as a filler material in papermaking: Impact of its preflocculation with cationic polyacrylamide

Abstract

Cationic polyacrylamide with different molecular weights were used to preflocculate the lime mud (LM) before it was added to the paper stock for handsheet preparation. The particle sizes, f potential, and morphology of the unpreflocculated and resulting preflocculated LM were studied. We found that high-molecular-weight cationic polyacrylamide (H-CPAM) led to larger LM flocs with a more positive f potential. The scanning electron microscopy images indicated that the morphological structure of the filler hardly changed during the preflocculation process. The effects of the preflocculation on the filler retention and paper properties were also investigated. The results show that the handsheets filled with preflocculated LM had better hydrophobicity and strength properties compared to handsheets filled with unpreflocculated LM, especially for H-CPAM-preflocculated LM. The paper formation was also improved, and the optical properties nearly remained the same. In addition, the LM preflocculated with H-CPAM had the highest filler retention. At a filler loading of 30%, the filler retention of the H-CPAM-preflocculated LM was higher than 86; it was less than 82.5% in other cases.

Structural evaluation of chitosan-modified precipitated calcium carbonate composite fillers for papermaking applications

“…10A. Higher improvement in tensile and burst with their corresponding correlation was reported by many while applying functionalized polymers in filler modification technology to achieve higher ash content [14,60,62].…”

Unmodified Starch Granules for Strengthening Mineral-Filled Cellulosic Fiber Networks Promoted by Starch Pretreatment with a Cationic Polymer Flocculant in Combination with the Use of an Anionic Microparticulate Material

“…Mineral fillers such as calcium carbonate and clay are commercially used in the production of printing/writing paper grades to deliver such significant benefits as cost reduction and printability/writability improvement. However, the addition of filler particles, particularly at high levels, can result in decreased paper strength due to their interference with fiber–fiber bonding. , This negative impact associated with filler addition can be mitigated by various proposed processes such as surface modification of filler particles with cellulose-bondable polymers or their composites, polymer-induced preflocculation of filler particles, and composite formation between filler particles and cellulosic fines/fibrils, allowing for increasing the filler content while maintaining an acceptable level of paper strength. − …”