Application of modified cellulose nanofibrils as coating suspension on recycled paper using size press

Abstract

Cellulose based nanomaterials have the great potential to be applied to paper as bulk additive or coating material to improve overall final properties, especially in secondary fiber. In the present work, the effect of applying different kinds of cellulose nanofibrils (CNF) to papers obtained from recycled fibers using size press on physical, mechanical and barrier properties was investigated and compared with the sole use of starch as coating material. The coating process of CNF was carried out by the addition of size press grade starch to coating suspension. As a cellulose source, wheat straw was evaluated and CNF was obtained through oxidative and enzymatic pretreatments. Results indicate that starch/CNF suspension improves the overall paper properties. As a result of the deposition of coating suspension contains of 4 % wt. periodate-oxidized CNF onto paper surface, tensile and burst indices of papersheets increased as 52.2 % and 194.4 %. Significant decreases were observed in air permeability as 69.8 %. Compression tests also have been conducted to evaluate papersheets end-use properties. In comparison to the other pretreated CNF, due to is lower viscosity, applying periodate-oxidized CNF as size press significantly increased the mechanical properties of the papers fabricated from the recycled pulps.

Potential use of nanofibrillated cellulose-loaded cationic starch solutions as coating formulation for recycled fluting papers

“…In the same manner, Balea et al (2016) reported a 40% increase in SCT values of OCC by the bulk addition of 4.5% CNF obtained from bleached eucalyptus kraft and bleached never-dried northern pine pulps. In contrast, Fidan et al (2021) indicated that the coating application of CNF provides better SCT values than bulk addition of the same amount of CNF. The authors reported a 133.3% increase in SCT values of recycled fluting papersheet after size press application of 4% CNF.…”

“…Thus, the internal bonding ratio increased drastically. Additionally, Fidan et al (2021) noted a substantial 110.9% improvement in internal bond strength following the surface sizing of 90 g/m 2 fluting papers using CS/CNF suspensions. Similarly, Tozluoğlu and Fidan (2023) reported 119.9% increase in internal bond strength of 110 g/m 2 recycled fluting paper sheets after size press of CS+4% CNF.…”

“…This is primarily due to the precision in adjusting CNF concentrations in surface applications, minimizing retention issues in post-fabrication applications. Fidan et al (2021) demonstrated significant improvements in burst strength following the size press application of CS/CNF suspension to 90 g/m 2 recycled fluting papers. The authors noted a remarkable 124% increase in burst strength with a 1.0 wt% CS/NFC suspension and up to 173% at 4% CNF concentrations.…”

“…Furthermore, there are studies in which higher CMT values (145 N) were obtained by using waste paper fibers (Masrol et al 2016). In contrast to the bulk addition, it is reported that the application of 4% CNF as coating suspension demonstrated remarkable increase as 105.8% when compared to the control samples (Fidan et al 2021). The ring crush test (RCT) and Concora crush test (CCT) values are regarded as an effective method to evaluate the contribution of materials to the compressive strengths of corrugated boxes.…”

High Performance of Paper Strength and Energy Savings in OCC Pulp Papermaking via MFC Addition

“…The purpose of fractionation is to utilize long fiber fractions for high-quality products and short fiber fractions for low-grade products, or to remix the short fiber fraction with a mechanically treated long fiber fraction to improve product quality and conserve refining energy [12][13] . Although this theoretical idea is generally accurate, it may not be applicable for repeatedly recycled fibers because the changes in fiber properties, including hornification and shortening of fiber lengths accompany recycling and are aggravated by recycling times [14][15] . However, fractionation of the recycled OCC and selective treatment of these fractions Refining is a mechanical strategy to improve the bonding properties of the fibers in the pulp, which in turn improves paper properties, such as tensile strength [16][17] .…”