Papermaking Additives Research Articles

Effect of paper-making additives on biodegradation of lignocellulosic fibers

Effect of paper-making additives on biodegradation of lignocellulosic fibers

Exploring the synergistic effect of anionic and cationic fibrillated cellulose as sustainable additives in papermaking

While cationic cellulose has yet to find a place in the paper industry, manufacturers show certain interest in a more recent material: cellulose nanofibers (CNFs), generally with negative surface charge. This work suggests both to be combined to increase the mechanical properties of recycled paper while preventing the use of synthetic polyelectrolytes as retention agents. On one hand, a bleached pulp was cationized by etherification, both as-is and following mechanical refining (15,000 PFI revolutions) and submitted to high-pressure homogenization, generating two different kinds of cationic CNFs. On the other, the same pulp was submitted to an enzymatic pretreatment and high-pressure homogenization, producing a negatively charged cellulose micro/nanofiber (CMNF). Two different cellulose-based systems consisting of each type of cationic CNF and the enzymatic CMNF were applied in the papermaking of both virgin and recycled paper. This study demonstrates the effective use of the cationic CNFs as retention agents during sheet formation, which together with the enzymatic CMNFs significantly enhanced the mechanical properties of both types of paper. The study found that refining before cationization favored the retention effect, primarily due to increased surface area and charge of the cationic CNFs, where remarkable increases in the breaking length of virgin (125.1%) and recycled paper (46.5%) were reached. The synergy between cationic CNFs and enzymatic CMNFs outperformed the use of commercial polyacrylamide, a non-biodegradable polyelectrolyte. This research highlights the potential of tailored CNFs in producing high-performance papers, while promoting sustainability and offering a plausible strategy to increase paper recycling rates.

Effect of Paper Preservation by Properties of Lining Starch Adhesives : Adhesion Properties According to Starch Type

In this study, the several types of starch adhesives, according to manufacture’s origin for the lining works and paper-making additives in paper mill, were prepared as a starch paste under uniform conditions. The potential and basic characteristics as an adhesive for preservation treatment were evaluated. The grain size of wheat starch varies depending on the processing of the country of origin, and it was judged that the grain size affected the gelatinization characteristics. Through inoculation of 3 types of fungi, ‘Aspergillus niger’ showed active growth activity in starch-based adhesives, and adhesives except tapioca showed the lowest activity in ‘Trichoderma viride’, which would accelerate the biodegradation of paper. In the future, based on the research data, we plan to study the effect on the evaluation of physical properties and paper preservation through paper lining accelerated aging for using the prepared adhesive.

Isolation, Identification, and Selection of Bacteria With Proof-of-Concept for Bioaugmentation of Whitewater From Wood-Free Paper Mills.

In the wood-free paper industry, whitewater is usually a mixture of additives for paper production. We are currently lacking an efficient, cost-effective purification technology for their removal. In closed whitewater cycles the additives accumulate, causing adverse production problems, such as the formation of slime and pitch. The aim of our study was to find an effective bio-based strategy for whitewater treatment using a selection of indigenous bacterial isolates. We first obtained a large collection of bacterial isolates and then tested them individually by simple plate and spectrophotometric methods for their ability to degrade the papermaking additives, i.e., carbohydrates, resin acids, alkyl ketene dimers, polyvinyl alcohol, latex, and azo and fluorescent dyes. We examined correlation between carbon source use, genera, and inoculum source of isolates using two multivariate methods: principal component analysis and FreeViz projection. Of the 318 bacterial isolates, we selected a consortium of four strains (Xanthomonadales bacterium sp. CST37-CF, Sphingomonas sp. BLA14-CF, Cellulosimicrobium sp. AKD4-BF and Aeromonas sp. RES19-BTP) that degrade the entire spectrum of tested additives by means of dissolved organic carbon measurements. A proof-of-concept study on a pilot scale was then performed by immobilizing the artificial consortium of the four strains and inserting them into a 33-liter, tubular flow-through reactor with a retention time of < 15 h. The consortium caused an 88% reduction in the COD of the whitewater, even after 21 days.

Analysis of Spotty Deposits on Fine Paper and Investigation of Key Factors Affecting Alkyl Ketene Dimer Spot Formation.

Defect spots degrade paper quality and often cause sheet breaks and other problems in the subsequent coating process. We encountered sporadic surges of defect spots on paper from a paper machine producing printing and writing grades of paper. We found that white or light-colored filler spots and waxy, translucent, elliptical spots accounted for 27.3 and 34.4% of these defects, respectively, and that both types of defect contained unhydrolyzed AKD as a major component. Paper machine’s wet-end deposits, however, did not contain unhydrolyzed AKD as a deposit component. We hypothesized that the colloidal stability of AKD was the main factor causing the increase in spot defects, and we verified this by deposit testing experiments. Among the papermaking additives tested, bentonite caused the most significant increase in AKD deposition during testing, which was attributed to its causing the electrostatic coagulation of cationically charged AKD emulsion particles. In contrast, anionically charged AKD emulsions showed improved stability and less deposit formation in the presence of bentonite.

Preparation and antibacterial activity of a cellulose-based Schiff base derived from dialdehyde cellulose and L-lysine

A cellulose-based Schiff base was synthetized via condensation reactions of dialdehyde cellulose (DAC) with l-lysine (Lys) and its antimicrobial activity was evaluated. The results of amino acid analysis, viscosity measurement, FTIR spectra, X-ray diffraction patterns, and solid-state cross-polarization (CP)/magic angle spinning (MAS) 13C-NMR indicated that the cellulose-based Schiff base (DAC-Lys) between DAC and Lys were formed. Thermogravimetric analysis (TGA) results showed that as compared with DAC, the DAC-Lys had diminished thermostability. When l-lysine content in DAC-Lys was 9.93 ± 0.35 g/100 g sample, the DAC-Lys exhibited high antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhimurium, and their MIC values were 7.5, 3.75, 7.5 and 3.75 mg/mL, respectively. The cellulose-based Schiff base, with good antibacterial activity, non-toxicity, and permissible biocompatibility, might be potential additives in papermaking for the introduction of antibacterial agents.

In-situ analysis of polyelectrolyte complexes by flow cytometry

Polyelectrolyte complexes (PECs) from common papermaking additives were prepared at different cation/anion ratios, resulting in colloidal light scattering particles. The polycations were cationic starches and polyDADMACs, while the polyanions were different carboxymethyl celluloses. The PECs were studied by turbidity measurements, as well as by flow cytometry (FCM). Turbidity maxima were detected close to the theoretical neutralization point of the polycation and polyanion. The turbidity response of the PEC mixtures varied with polyelectrolyte charge density. The PECs were in most cases quite stable over 24 h, but certain combinations resulted in unstable particles over time. Flow cytometry of PECs revealed clear populations of hydrophilic particles. The light scattering properties of PECs in side direction (SSC) and forward direction (FSC) were recorded for the different PEC combinations. The determined FSC and SSC offered information about very different PEC properties, and a new term was suggested for better understanding the mechanisms behind PEC formation; FSC/SSC. It was suggested that the determined FSC/SSC values were connected to the structural density of different particles. The premise was tested by analyses of solid, dense particles as well as swollen, soft particles. In addition to this, the hydrophobicity of PECs was determined by FCM. It was seen that the PECs were quite hydrophilic overall and that the measured hydrophobicities were lowest around the theoretical point of neutralization. Finally, the behavior of a coagulating PEC mixture as a function of contact time was studied with FCM.

Mechanical and chemical dispersion of nanocelluloses to improve their reinforcing effect on recycled paper

The use of nanocelluloses as strength-enhancing additives in papermaking is widely known since both cellulose nanofibers (CNF) and nanocrystals (CNC) present similar composition than paper but their exceptional properties in the nanometer scale confers a paper quality enhancement. However, some agglomeration problems in CNF and CNC through hydrogen bonding cause a lower improvement of mechanical properties of paper. Therefore, a better dispersion of both nanocelluloses can maximize their effect on paper properties, thus reducing the needed dose to get the same increment in tensile strength and then reducing material costs. To ease the implementation of these nanocelluloses in the production process of recycled paper, typically used operations of these industries have been used. Among them, those devoted to improve the homogeneous mixture of nanocellulose in the pulp suspension have been assessed. Firstly, pulping conditions were studied, including pulping time, temperature and need for soaking as variables. Secondly, some dispersing agents used in papermaking were considered, studying the effect of different types and doses. The highest tensile strength of paper was achieved by applying long pulping times (60 min), getting increments up to 30% with the use of soaking and polyacrylamide as retention system. However, with the use of a low dose of a dispersing agent (0.003%), tensile index can be still increased up to 20.6% avoiding these long times. This study can be of great interest of those researchers trying to implement the use of nanocelluloses as strength additive in papermaking.

The impact of paper constituents on the efficiency of mechanical strengthening by polyaminoalkylalkoxysilanes

The aim of the research was to evaluate the influence of certain components of paper such as lignin and papermaking additives (fillers and sizing) on the efficiency of a recently proposed treatment for simultaneous deacidification and mechanical strengthening with polyaminosiloxane copolymer networks. Mixed mechanical and chemical pulp papers containing various additives were treated with aminoalkylalkoxysilanes (AAAS) by immersion or by spray. Upon treatment, the deposited alkaline reserve varied from 0.34 to 1.14 mol kg−1. For all the papers, copolymers formed from binary mixtures of a di- and a tri-functional AAAS provided the best improvement in the mechanical properties, i.e. in the tensile strength and the folding endurance, indicating an increase in the interfiber bonding energy and in the paper flexibility and plasticity, respectively. It was found that fillers had no influence while sizing hampered the efficiency of the treatment. The presence of mechanical pulp was shown to have a significant impact on the effect of the treatments as well by increasing the tensile resistance more than the folding endurance, indicating an increase in the paper rigidity. This observation was attributed to the response of lignin to the treatment.

Assessing the influence of refining, bleaching and TEMPO-mediated oxidation on the production of more sustainable cellulose nanofibers and their application as paper additives

Agro-wastes valorization focusses on production of high value-added products, such as cellulose nanofibers (CNF), and contributes to reduce the environmental impact of these residues. CNF have been used successfully as papermaking additives and some previsions maintain that this sector will become the most important, demanding CNF at a reasonable cost. Furthermore, the optimization of the production process of CNF from agricultural residues would contribute to the goals of a circular economy, the development of rural areas and the costs reduction by producing CNF of the minimum quality fit-for-use in recycled paper. In this study, CNF was produced from two agricultural residues; corn (C-CNF) and rape (R-CNF) stalk pulps, pretreated with bleaching, refining and TEMPO-mediated oxidation. Coagulant and cationic polyacrylamide (dual system) and chitosan were the retention systems. Results show the difficulty of predicting the effect of CNF based on their properties, as fibrillation degree or anionic charge, on the improvement of mechanical properties of recycled paper. That is proved by the low differences in tensile index (TI) improvement (∼15% by adding 0.5% C-CNF combined with dual system), obtained with CNF with very different properties. The expensive TEMPO pretreatment could be avoid by applying bleaching pretreatment to the corn pulp, increasing the TI up to 15% without affecting drainage and decoupling the simultaneous deterioration of drainage with TI improvement (drainage time decreased nearly 50% and 20% adding bleached R-CNF and C-CNF, respectively, combined with chitosan). Similar improvements on TI can be achieved by replacing the dual retention system by chitosan without addition of CNF, but the combination of CNF and chitosan allows achieving the highest TI values.

Efficiency of Chitosan and their Combination with Bentonite as Retention Aids in Papermaking

In a previous work (Nicu et al. 2013), the flocculation efficiency of three chitosans differing by molecular weight and charge density were evaluated for their potential use as wet end additives in papermaking. According to the promising results obtained, chitosan (single system) and its combination with bentonite (dual system) were evaluated as retention aids, and their efficiency was compared with poly(diallyl dimethyl ammonium chloride) (PDADMAC) and polyethylenimine (PEI). In single systems, chitosan was clearly more efficient in drainage rate than PDADMAC and PEI, especially those with the lowest molecular weights; however, retention is considerably lower. This drawback can be overcome by using dual systems with anionic bentonite microparticles, with the optimum ratio of polymer:bentonite being 1:4 (wt./wt.). In dual systems, the differences in retention were almost negligible, and the difference in drainage rate was even higher, together with better floc reversibility. The most efficient chitosan in single systems was Ch.MMW, while Ch.LMW was the most efficient in dual systems. The flocculation mechanism of chitosan was a combination of patch formation, charge neutralization, and partial bridge formation, and the predominant mechanism depended on the molecular weight and charge density of the chitosan.

Strengthening Effects of Cleaner Papermaking Additives WEC on Papermaking with Second Fiber

Effects of additives WEC on strength properties of second fiber were investigated in this study. For single use of WEC02A, the improvement of ring crush index was most remarkable, which increased by 21% for bottom pulp and 31% for surface pulp. Significant increase was also achieved in burst index while the improvement of tightness and folding endurance was not obvious. Besides, combined use of 0.2% WEC02 and 0.3% WEC03S improved folding endurance, burst index and ring crush index of pulp by remarkable 105%, 23% and 52%, respectively, showing a great performance for pulp strength enhancement, being beneficial to broadening the utilization of second fiber.

Effects of Cleaner Papermaking Additives WEC on Sizing Degrees in Neutral Papermaking with Mechanical Pulp

Influences of self-developed additives WEC02/WEC03 on sizing of mechanical pulp are analyzed in this study. The results indicated that the optimal dosage for paper sizing were 0.2% (w/w) for WEC02, with sizing degree of 33 s, and 0.8% for WEC03, with sizing degree of 52 s. In addition, the combined usage of WEC02 (0.2%) and WEC03 (0.6%) at pH7.0 could get better sizing performance than single application of WEC02 or WEC03 with sizing value of 77 s. It is obvious that WEC02/WEC03 have great potential to improve sizing efficiency in neutral paperrmaking, leading to saving the sizes dosage and cutting down the production cost.

Using Neutral Sulfite Semichemical Pulp to Adsorb Lignocelluloses from Prehydrolysis Liquor of the Kraft-based Dissolving Pulp Process

The effective use of prehydrolysis liquor (PHL), from the kraft-based dissolving pulp production process, may fit into the concept of integrated forest biorefinery (IFBR). The dissolved organics in the PHL include hemicelluloses, lignin, acetic acid, furfural and extractives. Adsorption of hemicelluloses and lignin onto the neutral sulphite semichemical (NSSC) pulp fibres may be a potential method of utilizing the dissolved organics in the PHL. The principal goal of this work was to study the adsorption of lignocelluloses of PHL onto the NSSC pulp fibres. In addition to the typical process variables, the effect of using polymers, such as coagulant and flocculant, on increasing the adsorption, was investigated. The effects of time and temperature were examined. It was shown that adsorption reached its maximum almost in 1 h. Also, it was demonstrated that a higher temperature improved the adsorption. Furthermore, the use of cationic polymers, such as polydiallyl dimethyl ammonium chloride (PDADMAC), a coagulant (Nalkat 2020) and flocculant (Ultimer 1470), could enhance the adsorption of lignocelluloses from PHL onto NSSC pulp fibres. The maximum lignin and hemicelluloses adsorption was 160 mg/g and 320 mg/g onto pulp (58% and 22% removal from PHL), respectively. It is concluded that lignocelluloses of the PHL can be adsorbed onto NSSC pulp fibres so as to work as papermaking additives; and typical polymers, such as coagulant and flocculant, can be used to enhance the lignocelluloses adsorption. Keywords: Adsorption, Lignocelluloses, Lignin, Hemicelluloses, Coagulant, Flocculant, NSSC pulp, Pre-hydrolysis liquor, Biorefinery.

Flocculation Efficiency of Chitosan for Papermaking Applications

There is a large interest in bio-polymers as environment-friendly alternatives to synthetic additives in papermaking. In this work, the behavior of three chitosans with different molecular weights and cationic charges were investigated as flocculation additives in papermaking on two systems: calcium carbonate (GCC) and pulp/GCC suspension. Comparison was made with two traditional cationic polymers used in wet end chemistry (poly-diallyldimethyl-ammonium chloride (PDADMAC) and poly-ethylene imine (PEI)). Flocculation efficiency was evaluated by flocculation parameters (mean floc size and number of counts) and by floc behavior under shear conditions, using a focused beam reflectance measurement (FBRM) technique. Results indicated different behaviors between the three chitosans when they were used for the flocculation of GCC and pulp/GCC suspensions. Chitosans were found to be more efficient over PDADMAC and PEI for flocculating small particles of the GCC suspension, but less efficient for increasing floc sizes, regardless of their MW or CCD. Flocculation parameters for pulp/GCC suspensions suggested the flocculation behavior of chitosan was close to that of PEI, but chitosan had higher efficiency and affinity towards cellulose fibers.

Influences of configuration and molecular weight of hemicelluloses on their paper-strengthening effects

Xylan, galactoglucomannan, arabinogalactan and hemicelluloses with different molecular weights were prepared from wood and then used as wet-end additives and surface sizing agents in papermaking. The results showed that xylan, galactoglucomannan and arabinogalactan all had obvious paper-strengthening effect. As wet-end additives, galactoglucomannan had the best effects, followed by xylan and then arabinogalactan. As surface sizing agents coordinating with starch, xylan showed the best sizing effect (paper-strengthening effect and water resistance), followed by galactoglucomannan. The effects were both greater than that of starch alone. Furthermore, hemicelluloses with higher molecular weights had more significant effects. The results could provide some reference for the use of hemicelluloses in nature and papermaking waste liquor to improve paper physical strength. Although hemicelluloses in APMP (alkaline peroxide mechanical pulp) waste liquor was degraded to a certain degree, it also showed good paper-strengthening effects. Starch as an important papermaking additives comes mainly from food. The hemicelluloses, especially in the high-yield-pulp waste-liquor, can replace starch in papermaking to some extent, which might be beneficial from economic, energy and food standpoints.

The Preparation and Application of the Cationic Biopolymer Based on Xylan-Rich Hemicelluloses from Agricultural Biomass

During the last few years increasing attention has been paid to the exploitation of hemicelluloses as biopolymer resources because they are available in very large amounts in organic wasters from renewable forest and agricultural biomass. The efficient method to prepare the cationic biopolymers based on xylan-rich hemicelluloses from agricultural biomass has been developed in this paper. These biopolymers with cationic functional groups, having many good properties such as solubility, bio-degradation, cationic or ampholytic polymers, were synthesized by the chemical modification of sugarcane bagasse xylan-rich hemicelluloses with CHMAC and preferably with ETA in different media. These biopolymers based on xylan-rich hemicelluloses with the degree of substitution (DS) up to 0.55 could be obtained by varying the molar ratio of ETA or CHMAC to anhydroxylose units in hemicelluloses from 0.5 to 3.0. 13C NMR confirmed that cationic groups were grafted onto the backbone of hemicelluloses. In addition, their applications in papermaking as dry strengthen agent were investigated. It was found that these biopolymers could obviously improve the physical properties of hand sheets formed from old corrugated container pulp fibres. These results mentioned above highlight the remarkable potential for using the hemicelluloses-based biopolymers as wet end additives in papermaking.

Preparation of Guanidine Derivative Polymers as Novel Functional Additives for Value-Added Hygiene Paper

In this paper, two guanidine derivative polymers were synthesized by reacting polyhexamethylene guanidine hydrochloride (PHGH) with starch and epichlorohydrin (EP) respectively and used as potential functional additives in papermaking. The molecular structure of the guanidine derivative polymers were characterized by FTIR and 2D NMR. PHGH- modified starches exhibited high antimicrobial activities against E. coli and the growth inhibition reached almost 100% in the presence of 1.0 wt.% PHGH in wood fibers. UV260 absorption was applied to reveal the dynamic antimicrobial process of guanidine derivative polymer obtained with PHGH and EP. Results showed that most of bacteria was deactivated within a few mins and the intracellular components were leaked when the concentration of the guanidine derivative polymer were higher than the minimum inhibitory concentration (MIC).

The effect of hemicellulose extraction on fiber charge properties and retention behavior of kraft pulp fibers

The integrated forest biorefinery (IFBR) concept provides a promising opportunity for the development of the pulp and paper industry. One proposed next generation technology for an integrated forest biorefinery is the extraction of hemicelluloses, allowing the co-production of pulp and different hemicellulose-based chemicals. In addition to paper properties, hemicelluloses are known to be important for the function of cationic papermaking additives, because they are the main source of charged groups in fibers. This paper shows that the alkaline extraction of hemicelluloses from bleached kraft pulp decreases both the total and surface charge of the pulps. It was found that the decreased fiber charge leads to increased filler retention with fixed retention aid dosage. The reduction observed in the fiber surface charge for alkali-extracted pulp was mainly attributed to the decrease in the amount of anionic groups located in fines.

Polyvinylamine at last

AbstractA sustained effort to develop and commercialize a practical radical addition route to amine functional polymers (AFPs) resulted, after almost 20 years, in the successful completion of a world scale monomer plant to produce N‐vinylformamide (NVF). NVF is readily polymerized and its polymers are easily hydrolyzed to reactive and atom economical polyvinylamine (PVAm) or its salts. This highlight touches on work by many companies, but focuses on efforts at Air Products and Chemicals, tracing the origins, rational, challenges, technical and commercial advances, and failures. Practical routes to new AFPs, copolymers, and derivatives across the entire molecular weight range (MW &lt; 103 to &gt;106) were achieved. NVF offers access to multiple water soluble, water dispersible, and nonwater soluble polymer markets, including papermaking additives and coatings, water treatment polymers, enhanced oil recovery polymers, radiation cure monomers, stabilizers, dispersing agents, surfactants, and crosslinkers. Lessons learned along the road to commercializing major new chemical technologies are also highlighted. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2257–2283, 2010