Encapsulation of precipitated calcium carbonate fillers using carboxymethyl cellulose /polyaluminium chloride: preparation and its influence on mechanical and optical properties of paper

Abstract

Inorganic fillers are usually used in papermaking industry to reduce production costs and enhance paper optical properties. As an attempt to improve fillers application in papermaking, carboxymethyl cellulose (CMC) and poly aluminum chloride (PAC) were used to encapsulate precipitated calcium carbonate (PCC) filler and modify its surfaces. In the first step, the optimum conditions for filler treatment (i.e. pH, CMC and PAC contents) were obtained. Through the second step, different amounts of CMCencapsulated PCC were added to fiber suspension and some hand-sheets were made. Then, the effect of modified filler addition in different levels of 20, 25, and 35% on mechanical and optical properties of paper was investigated. The PAC dosage was found to be a critical factor for effective encapsulation of PCC fillers by carboxymethyl cellulose. When the dosages of CMC and PAC were 4% and 0.8% (based on the dry weight of PCC), respectively, filler modification caused to improve significantly the retention by more than twice. Strength properties of the hand-sheets fabricated with the CMC/ PAC-modified PCC were also found to be significantly better than those obtained with the unmodified PCC at similar levels of filler content. In addition, the brightness and opacity of the filled papers at 30% addition of CMC-modified fillers were strikingly enhanced to 88,45 and 77%, respectively. SEM observations of the filled papers also demonstrated that CMC-encapsulated filler particles were clustered and retained efficiently onto the fiber network. The present method for modification of PCC may provide an alternative approach to increase the filler amount in the paper structure by alleviating filler drawbacks.

A study on effect of modified calcite on filler retention and mechanical properties of fluting papers

“…As the modified filler add-on increased, the generally expected strength values did not decrease, but an increase in non-significant values was observed (Figure 4). As the reason for the increases, it is seen that the effect of starch internal adhesion was realized, and with the increase in MC dosage, calcite grains encapsulated with cPAM support increased the retention by mak-ing wet-end bonding to the fibers and also preserved the strength (Chen et al, 2020;Mousavipazhouh et al, 2018) In accordance with the general studies, the filler addition showed a significant decrease in values such as CMT and breaking length (Bajpai, 2018). Nevertheless, it is thought to be higher than the filler-free paper values, which is due to the internal bonding effect of starch.…”

“…4). As the reason for the increases, it is seen that the effect of starch internal adhesion was realized, and with the increase in MC dosage, calcite grains encapsulated with cPAM support increased the retention by making wet-end bonding to the fibers and also preserved the strength (Chen et al, 2020;Mousavipazhouh et al, 2018).…”

Calcium Carbonate–Carboxymethyl Chitosan Hybrid Materials

“…Some research in the field of papermaking has shown the compatibility of precipitated calcium carbonate (PCC) with organic compounds [ 5 , 6 , 7 , 8 , 9 ]. The most modifications of precipitated calcium carbonate (PCC) regarding the improvement of its filler properties are those related to the use of bio-additives (starch, alginate, cellulose, and chitosan) which reduce the negative impact of fillers on the paper properties and on the technological process [ 10 , 11 , 12 , 13 ].…”