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Four major toners are used in the printing industry, cyan, magenta, yellow and black (Key) for making color images on paper. Paper brands suitable for printing have thin mineral/latex coatings, and toners are applied on top of the coating in the printing process. Chemical compositions from toner to toner, as well as from coating to coating, vary according to the needs of the end user. Interactions between the toner and the coating define the final color formation of the images in printing. Hence, it is important to study characteristics and dynamics of toners on coated papers. In this paper, we have used laser-induced plasma spectroscopy (LIBS) to provide information on elemental distributions of the toner and the coating layers on three coated papers and the base paper at a sub-micrometer resolution. Ablation crater depth profiles in the three different material layers were converted into metric scale by combining elemental information from the LIBS measurements and optical profilometry. Ablation efficiencies for a toner of 150 nm/pulse, for a coating of approximately 350 nm/pulse and for a base paper of approximately 1 μm at a fluence of 0.6 J/cm2 of an ArF excimer laser were determined. Using these results, the average layer thicknesses of the toner and the coating layers were evaluated. The detailed analysis of the elemental profiles of the two cyan toners studied revealed strong accumulation of silicon and titanium compounds of the toner on the toner–air interface but also on the toner–coating interface, but to a much smaller extent. The observation reveals the significance of toner component diffusion due to substrate–machine interaction in the printing process. Such diffusion processes must have an important role in final color formation of the images in printing. The method developed provides a unique and accurate means to study toner diffusion processes in coated papers under printing conditions.

The effects of bio-based strengthening agents and mineral filling procedure on the 3D elongation of chemi-thermomechanical pulp (CTMP) handsheets with and without mineral (PCC) filling have been investigated. The 3D elongation was measured using a press-forming machine equipped with a special converting tool. The strength of the handsheets was altered using either cationic starch or microfibrillated cellulose. Precipitated calcium carbonate (PCC) was added to the furnish either as a slurry or by precipitation of nano-sized PCC onto and into the CTMP fibre. The 3D elongation of unfilled sheets was increased by the dry-strengthening agents, but no evidence on the theorised positive effect of mineral fill on 3D elongation was seen in either filling method. The performance of the strengthening agent depended on whether the PCC was as slurry or as a precipitated PCC-CTMP. The starch was more effective with PCC-CTMP than when the PCC was added directly as a slurry to the furnish, whereas the opposite was observed with microfibrillated cellulose. The 3D elongation correlated positively with the tensile strength, bursting strength, tensile stiffness, elastic modulus and bending stiffness, even when the sheet composition was varied, but neither the strengthening agent nor the method of PCC addition affected the 3D elongation beyond what was expectable based on the tensile strength of the sheets. Finally, mechanisms affecting the properties that correlated with the 3D elongation are discussed.

There is currently a great demand for sustainable and bio-derived coatings for fiber-based packaging materials, which are technically implementable with a high performance. The aim of this work was to investigate the grease resistance of coatings prepared from methyl nanocellulose when applied on paperboard. Co-additives selected from native microfibrillated cellulose (MFC) and hydrophobically modified ethyl(hydroxyethyl)cellulose (EHEC) were used in order to determine their impact on film formation and crack resistance for folds. Small and moderate coat weights were applied in order to determine the critical coat weight for the barrier properties. It was found that high grease resistance can be achieved with methyl nanocellulose and a combination of methyl nanocellulose and MFC coatings. Contact angle determinations for water on uncoated and coated materials showed that EHEC-MFC films have a very high contact angle which is due to both the surface chemistry and roughness. This indicates and confirms that EHEC may facilitate the wetting of oil and greases. Methyl nanocellulose mixed with hydrophobically modified EHEC significantly changed the barrier properties indicating a change in the film formation.

Foams were prepared from hydrophobically modified ethyl(hydroxyethyl) cellulose (EHEC), methyl nanocellulose, and native microfibrillated cellulose (MFC). Their film- and foam-forming abilities, stabilities, and suitabilities for foam coating on different substrates were investigated. The role of EHEC as a polymeric stabilizing agent was also studied. The EHEC-MFC foams showed greater stability and water-holding ability under pressurized dewatering than MFC foams prepared in the presence of a surfactant. A foam could be created with methyl nanocellulose without any foaming agent. Selected nanocellulose gels and foam formulations were used to coat various substrates. The surface was efficiently closed by gel and foam coatings prepared from the methyl nanocellulose and EHEC solutions, which was ascribed to good coating holdout. Coatings on papers with different levels of smoothness/density and hydrophobicity/ hydrophilicity confirmed that foam-substrate interactions affected the coat quality. The air permeance was reduced by 99% and 64% with a methyl nanocellulose coating and an EHEC-MFC coating, respectively. An EHEC-MFC coating created a hydrophobic surface on a hydrophilic substrate, and methyl nanocellulose improved the oil resistance even at a low coat weight.

The use of nanomaterials and polymers from renewable resources is important in the search for sustainable alternatives to plastic-based packaging materials and films. In this work, self-supporting thin films prepared from derivatized and non-derivatized nanocellulose and cellulose derivatives were studied. The effect of drying temperature on the film-forming behavior of compositions comprising hydrophobically modified ethyl(hydroxyethyl)cellulose (EHEC), native microfibrillated cellulose (MFC) and nanocellulose made from methyl cellulose was determined. The interaction between the components was assessed from viscosity measurements made at different temperatures, the result being linked to a thermal-dependent association during liquid evaporation, and the subsequent barrier and film-forming properties. The effect of temperature on suspensions was clearly different between the materials, confirming that there were differences in interaction and association between EHEC–MFC and methyl nanocellulose–MFC compositions. The amphiphilic EHEC affected both the suspension homogeneity and the film properties. Air bubbles were formed under certain conditions and composition particularly in MFC films, dependent on the drying procedure. The presence of air bubbles did not affect the oxygen transmission rate or the oil and grease resistance. An increasing amount of MFC improved the oxygen barrier properties of the films.

Abstract Composite sheets consisting of elongated and aggregated cationically charged precipitated calcium carbonate (PCC) and native microfibrillated cellulose (MFC) were prepared with a wet laying method. The furnishes were prepared with and without an anionic flocculating agent (polyacrylamide) in order to adjust the structure of the sheet. The samples were compressed (densified) in order to determine the particle and microfibrillated cellulose-PCC structure coalescence and densification, as well as its subsequent influence on liquid absorption behavior. The densification affected both the vertical and lateral distribution of PCC, but the flocculating agent enhanced the compression stability and stabilized the sheets against PCC material flow. The differences between the sheets made with and without the flocculation aid affected the absorption of an anionic dye-based fluid ink, which was evident as a higher print density and less print bleeding. The absorption behavior was dependent on the sheet structure, especially on the PCC distribution within the sheets. Finally, the role of MFC on floc structure and floc formation is discussed. Graphic abstract

In paper containing multilayer composite structures and laminates, polarization is usually investigated under dry environmental conditions. The aim of this research is to determine polarization dependence of paper and paper-dielectric structures on environmental relative humidity (RH). The role of each component was identified. The obtained and recorded data are used for identification and clarification of the physical mechanism of polarization. The polarization was studied by applying a dosed charging and forced discharge method and was evaluated by a depolarization potential and its formation kinetics. The polarization level of investigated structures increases with RH and is determined mainly by the paper (cellulose) and moisture content in it. In composite structures of the paper between dielectric films and dielectric on paper the polarization dependence on RH correlates with moisture absorption isotherm. It was found that the surface electrical conductivity of paper distorts the results of the paper and structure paper on dielectric. Analysis of the formation kinetics of the depolarization potential together with the potential decay of the charged paper has determined the role of orientation polarization and space charges. The formation of space charges is faster than orientation polarization and dominates in polarization process at higher RH. The process modeling by superposition of two exponents confirms this polarization mechanism.

The temperature-dependent association between methyl nanocellulose and hydrophobically modified ethyl(hydroxyethyl)cellulose (EHEC) was determined. Methyl nanocellulose was mixed under different concentrations with EHEC in aqueous media. The hydrophobic association, cloud point and temperature-dependent flocculation were studied using turbidity, rheometry and laser diffraction analysis. The phase separation of EHEC samples containing different amounts of methyl nanocellulose in 1.0 wt% solution was measured between 20 and 70 °C, showing that the cloud point of the solutions increased with increasing nanocellulose content. An increase in the low shear viscosity and gelation behavior of the mixture with the highest methyl nanocellulose content in conjunction with changes in cloud point indicated that the hydrophobic nanocellulose strengthened the hydrophobic association and the gel network. A bimodal particle size distribution was observed for both the pure EHEC and hydrophobically modified nanocellulose reference solutions, whereas the mixture had a trimodal particle size distribution when being diluted. The colloidal stability and re-structuring mechanism of the dilute methyl nanocellulose suspension after shear and the role of birefringence are discussed.

Abstract CaCO3-pulp composite was prepared via precipitation of calcium hydroxide in the presence of pulp. In order to investigate the precipitation selectivity and mechanism, the substrate pulps and the obtained composites were fractionated (R30, R100, R200, R400 and a sedimented fraction that passed the 400 mesh wire) using a Bauer-McNett unit. The main fractionation criterion was therefore fiber length. The pulp used was CTMP (chemithermomechanical pulp), yielding a precipitated calcium carbonate-chemithermomechanical pulp (PCC-CTMP) composite with a targeted PCC-to-CTMP ratio of 1:1. The PCC consisted primarily of nano-sized primary particles which formed aggregates and clusters on the fibers. When the fiber morphology, zeta potential and surface charge density of the fractions were determined, a correlation was found between the surface charge density of the CTMP and the ash content of the corresponding PCC-CTMP fractions. This supports the hypothesis that the precipitation on the CTMP fiber is driven by the charge interparticle interaction. The use of refined CTMP furnishes and fractionation of the PCC-CTMP furnishes demonstrates that PCC is preferably fixed on fines and fibrils since it appears at a higher content in the fines fractions. Fiber activation via fiber split, removal of primary wall and surface defibrillation enhanced the affinity of the PCC for the fibrils. The laboratory handsheets prepared from the material demonstrated the importance of controlling the substrate fiber properties for the mineral-fiber composite, e.g. via refining, as differences between the refining levels and fractions were found to lead to differences in both optical properties and bonding. Graphic abstract

Microfibrillated cellulose (MFC) with and without added CMC was exposed to short-term dynamic thermal treatment using a steam jet cooker. The effects of the elevated temperature (130 °C, ∼3 bar) and shear forces on the rheology, crystallinity index, UV/VIS adsorption and water retention were measured. Jet cooking increased the viscosity and gel strength of the MFC and MFC/CMC mixture but with CMC alone a slight decrease in viscosity was observed. The water retention capacity and crystalline indices of the MFC were not greatly affected by the short-term thermal treatment and shear forces, although a slight increase in the UV/VIS absorbance was observed.

This study examines the effect of pulp type on the formability and elongation of paperboard, which are of key importance when producing 3D packages. Material performance was studied with a press-forming machine using laboratory handsheets as substrates. The handsheets were prepared from bleached softwood and hardwood kraft pulps, chemi-thermomechanical pulp, recycled newsprint, and mixtures of birch kraft and other pulps. The effect of microfibrillated cellulose (MFC) on substrate properties and material formability was also investigated. The 3D elongation of MFC-free handsheets varied between 1.2 and 5.5%. Depending on the pulp type and sheet composition, three essential sheet properties were recognized. These properties were bulk, elastic modulus and bending stiffness, the first two of which affect material bending stiffness. Sheets made from softwood fibers were superior to other samples, but their low bending stiffness resulted in distortion of formed trays. A partial replacement of birch kraft with recycled newsprint did not lead to a loss of sheet extensibility, which suggests that the interactions between the converting tools and the substrate have a great effect on material convertibility. Scanning electron micrographs showed that the pulp type affects the mechanism behind fracture initiation. The ability of MFC to increase extensibility was limited to mechanical pulps, indicating the important role of the main pulp component in defining tensile properties.

The effect of water-soluble anionic binders and a modified cationic-precipitated calcium carbonate layer-by-layer structure on dye ink spreading and absorption has been studied. The multilayered coating was alternately spray-coated onto the substrate in order to determine dye interdiffusion and specific interaction including solvent absorption behavior in the nano- and microporous layers. The amount of the hydrophilic binder in the top coating was varied in order to adjust the porosity and to determine the effect of electrostatic charge interaction and to adjust dye fixation. Cationic nano- and microporous coatings and particle assemblies were created by spray-coating with cationic calcium carbonate precipitated in the presence of PDADMAC. The deposition of dye on the various coatings revealed that a small amount of anionic binder in the top coating favoured the absorption and spreading of dye and solvent, whereas a higher binder dose closed the pores and reduced the dye fixation and rate of solvent absorption. Although the top layer is essential for dye retention, it was demonstrated that the multilayering is essential not only for dye setting and dye capturing mechanism but can be utilized for vertically controlling the dye penetration and retention in the formed hydrophilic gel complex, which has a significant influence on optical effects and mechanical durability.

This paper reviews the use of the Bristow Absorption Tester (known also as the Bristow wheel) in the characterization of fiber-based substrates. The Bristow wheel is a laboratory-scale instrument that has been designed for studying substrate wettability and dynamic liquid absorption properties in short time intervals, which are important in many converting and printing processes of paper and paperboard. The tester also gives information about substrate roughness. The Bristow wheel has shown great usefulness in predicting print quality especially in inkjet applications, in which a good correlation between print quality (letter area) and ink penetration rate has been found by several researchers. The apparatus is particularly useful in dynamic wetting studies, but it has also been successfully used in numerous other research purposes such as the determination of the degree of sizing, evaluation of material glueability, and various coatability studies. Modifications of both the testing principle and the tester structure have also been reported. These include e. g. equipping the apparatus with a corona unit that makes it possible to mimic a printing process on a relevant time-scale. This review summarizes the reported applications of Bristow wheel with a special focus on tester performance and versatility.

Optimization of storage conditions is essential for successful converting of paperboard. This paper investigates the effect of blank moisture content on the dimensional accuracy and rigidity of press-formed paperboard trays. The trays were manufactured from uncoated, pigment-coated and extrusion-coated paperboards and multi-layer materials using fixed process parameters. Because of the different layer structures and coatings, the paperboards showed different hygroscopic behavior. Prior to converting trials, the bursting strength of paperboards under different moisture conditions was assessed. It was found that the moisture content has only a minor influence on bursting strength, but moisture affects blank curling tendency and dimensional accuracy of the tray. A high blank moisture content led to a loss of the dimensional stability and load-bearing capacity of trays, although based on earlier knowledge it is evident that the moisture content should be high for successful press-forming. As expected, a low blank moisture content increased the prevalence of ruptures in forming but the resulting trays were stiffer and their dimensional accuracy was better. It was suggested that the increased stiffness is related to a more efficient moisture removal during the press-forming, so that the fiber network is more effectively consolidated due to e. g. the formation of hydrogen bonds.

The aim of this study was to determine the effects of hydrothermal treatment of microfibrillated cellulose (MFC) on its gel stability, water retention and rheological behavior. MFC gel was prepared by fibrillating endoglucanase pre-treated, never-dried dissolving pulp. The MFC gel samples were then exposed in a static chamber for different times at different temperatures. At temperatures of 120–150 °C, the viscosity profile of the gels was not significantly changed and a characteristic series of 3 successive regimes in the course of increasing shear rate, showing different behavior was revealed. The amount of water released by the samples under pressure, on the other hand, was notably increased after hydrothermal treatment. After further exposure to prolonged treatment times (24 h) and higher temperature (180 °C), a significant decrease in viscosity and shear modulus was observed. Analysis of filtrates revealed the formation of cello-oligosaccharides, glucose and HMF and a decrease in surface tension indicating peeling and molecular degradation of the sample matrice. The microfibralled cellulose sample decomposition and gel network structure breakdown on a molecular level is discussed.

A packaging material requires a proper interaction with regard to water vapour transmission between the product and the outside environment. For many fresh food products such as bakery goods, fruits, and vegetables, microperforation is utilised to extend the shelf life of the foodstuff and to provide better food quality. The microperforation potential of five commercial polymeric films has been evaluated using a pulsed fibre laser technique, and significant differences were found between the films in the penetration of the laser beam and in the diameter of the perforation. Breathable polymeric packaging films were prepared with an average laser power of 20 W and a pulse duration of 200 ns. The numbers of holes (80 μm in diameter) in the films were approx. 2000 holes/m2 and 4000 holes/m2. As expected, the number of perforations affected the water vapour transmission (WVT): the WVT was 11 g/m2/d for unperforated film, and 60 g/m2/d for the film with 4000 holes/m2, indicating that the fibre laser can be used successfully for microperforating this type of polymeric films. However, microscopic and microtomographic analyses revealed major differences in hole formation behaviour and in the wall structures of the microperforations.

Press forming process is an important manufacturing process to produce paperboard tray packages. During the press forming, sever deformation occurs at the intricate shapes that can cause localized strains and the fracture. The formability can be improved by the crease lines and controlling parameters. Creases reduce the confine stiffness and assist the folding of the paperboard into the complex shapes. In this paper, the press forming process is modelled and simulated with the aid of finite element method. We focus especially on control parameters such as blank-holding force, friction and the behavior of creases at different forming levels. A stress-based failure criterion is also designed and modelled to analyze the rupture. The FE-model consisted of the male die, female die, blank holder and paperboard blank. A commercial material with the grammage of 290 g/m 2 and thickness of 0.353mm is used in this study. The paperboard is modelled as an elastoplastic material and Hill’s yield criterion with isotropic hardening is used to interpret the hardening behavior. The creases are modelled as hinge connectors (one rotational degree of freedom). The failure criterion is implemented by the user-defined subroutine in Abaqus. In conclusion, the developed model can be used to analyze the crease behavior, strain mapping and the prediction of failure, which enables the better understanding of the paperboard converting in the press forming process.

High purity (>99.5%) NaCMC solution was heated in ion-exchanged water and in an aqueous 10 mM NaHCO 3 buffer solution and studied as a function of time and temperature. The effects of thermal treatment on viscosity, pH, molecular weight and cationic demand of the solutions were measured. It was found that the anionic groups of carboxymethylcellulose are relatively stable against thermally induced degradation, but a reduction in NaCMC chain length and viscosity was observed. Only the highest applied temperature (177 °C), especially without any pH control, destroyed the side groups of the NaCMC. This was observed as a decrease in cationic demand and in the formation of glycolic acid. The application of buffer was noticed to retard the degradation of side groups. The observed decrease in viscosity with increasing reaction time in the presence of air was relatively well described by a second order reaction.

The aim of this investigation was to determine the role of negative direct current and alternating current (plasma) corona treatments in modification of bio-based dispersion barrier coatings and the response of replacing fossil-based binder with a thermoplastic bio-based binder (starch). The study emphasizes the importance of understanding and optimizing electric corona discharge in order to obtain high oxidation level without harming the substrate and causing unintentional treatment of the reverse side. The coatings were exposed to different corona treatment conditions using a novel developed sheet-fed laboratory-scale device. Corona-induced topographical, mechanical and surface chemical changes were observed from atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle and surface energy measurements. XPS results indicated further that partial starch decomposition occurred after plasma treatment. Coated surfaces became substantially smoother after both treatments suggesting that nanoparticle migration and re-orientation effects occurred. Additionally, reverse side effects and strike through were also discussed.

Carbon nanomaterial applications are expected for consumer use within next decade. Risk management methods are reviewed by National Institute for Occupational Safety and Health, Safe Work Australia, Health and Safety Executive, and additionally Dupont's and Environmental Defense Fund's Nano Risk Framework. A new risk management method for handling carbon nanoparticles is presented, directed especially to universities and to research institutes. Small scale operations are different than those conducted in enterprises. Typically work started from the scratch, and researchers with limited experience of working with hazardous materials are distinctions to enterprise work flows. The promoter in this study has also been the life-cycle perspective for handling hazardous materials already in early stages of the research. Two risk evaluation cases are introduced in the use of multiwalled carbon nanotubes. The method behind inference logics in risk evaluation is demonstrated, and it was successfully implemented in the real carbon nanotube research project. The straight-forward spreadsheet implementation is an additional advantage due to short set-up time, due to easy system maintenance and due to the easy use of different evaluation parameter weights.

The precipitation of micro- and nanoparticles of calcium carbonate onto lignocellulosic microfibers was investigated at different microfiber concentrations with and without polyacrylic acid (PAA), i.e. a polymer commonly used to form polymer-induced liquid precursors of CaCO3. Concentrations of PAA, Ca(OH)2, CO2 and microfiber were varied in order to study the impact of reaction conditions on PCC formation in a batch reactor operated at ambient temperature. High resolution scanning electron micrographs of the samples show that both microfiber concentration and PAA dosage affected the nucleation and crystal growth of PCC filler on cellulosic fiber. Interestingly, at higher microfiber concentrations, larger amount of nano-sized spherical crystals were formed on the microfibers. A higher dosage of PAA, on the other hand, resulted in less nucleation on the microfiber, suggesting a preferential bulk nucleation mechanism. A higher concentration of PAA during the precipitation also led to the formation and stabilization of amorphous CaCO3, which was supported by SEM images and XRD analysis (lack of characteristic crystal structure).

In the original publication, the less than symbol () in Tables 2 and 4.

The aim of this study was to determine hydrothermally induced changes in the physico-chemical properties of a fine microfibrillated cellulose (MFC). The MFC was prepared from a monocomponent endoglucanase-treated never-dried birch kraft pulp which had been run several times through a microfluidizer in order to obtain a sample substantially free from fibers or fiber fragments. The fine MFC was subjected to hydrothermal treatment at $$150\,^{\circ }\hbox {C}$$ for 0.5, 2.5, 4.5, 8.5 and 20.5 h, after which the viscosity, water-retention capacity, surface charge, discoloration and formation of hydrolysis products were determined. The viscosity, surface charge and water-retention capacity of MFC decreased as a result of the treatment but in oscillatory measurements the storage and loss moduli increased. Hydrothermal treatment also caused discoloration of the sample which could not be fully washed away with water. Surface analysis with XPS revealed no significant changes in the surface structure of the dried MFC cakes but the filtrates after the hydrothermal treatment were complex mixtures of sugars, organic acids and furans. The main degradation products detected were xylose and xylobiose, but isomerization products of sugars (xylulose, fructose) were also found in the filtrates. In addition numerous organic acids, including formic, glycolic, lactic and xylonic acid, were identified in the filtrates, showing that both acid and alkaline catalyzed reactions occur due to dissociation of water into $$\hbox {H}^{+}$$ and $$\hbox {OH}^{-}$$ .

The material properties of substrates such as paperboard are normally measured under laboratory conditions but their physico-mechanical properties are likely to change during a press-forming process. A measurement device of has therefore been developed to obtain real-time data of paperboard tray production and a new insight into phenomena related to press forming and tool-substrate interaction. An existing mould set was modified for measurement of the forming force by replacing the male mould with a mould that included a set of force sensors. Detection of defects such as ruptures require the use of multiple force sensors that make it possible to obtain more detailed measurement data. To validate the performance of the device, a number of solid bleached paperboard (SBB) materials were selected to represent different kinds of coated paperboard structures in order to obtain a comprehensive general view of the phenomena occurring in the tray-pressing process. The friction coefficients of the test materials were measured by two different methods Force values obtained with the measurement device were used to calculate the friction coefficients and these were also obtained by a standard laboratory test method. The measurement device was also utilized to detect rupturing during the forming of the paperboard trays.

A study was conducted that demonstrated that the blending of edible oils leads to changes in surface tension, thermal properties, viscosity, and oil penetration times through a barrier-coated paper ...

A method based on direct UV-detection was developed for the qualitative and quantitative determination of oligosaccharides simultaneously separated by capillary electrophoresis (CE). Reference compounds consisting of five xylo- three manno- and five cello-oligosaccharides were concurrently measured in a highly alkaline solution without derivatization. Sodium and potassium cations were used in the electrolyte solution to adjust the electrokinetic properties of the oligomers by controlling the mobility of charged species and to improve the resolution in baseline separation. The quantification range extended from 25 to 125 mg/L with linear correlation $$\hbox {R}^{2}=0.986{-}0.997$$ for all analytes other than xylobiose and cellobiose, for which the range was 50–200 mg/L ( $$\hbox {R}^{2}=0.995$$ ). The CE method developed was further applied to determine oligosaccharides from hot-water extracts of a bleached birch and pine kraft pulp, in which the oligosaccharides typically exist as complex mixtures.

Dissolving grade pulps are used to manufacture regenerated cellulosic fibres. One promising process for the production of regenerated fibres utilises endoglucanse rich cellulases in the modification of dissolving pulp into alkaline soluble form. The aim of this paper was to characterise cellulases produced by Trichoderma reesei that are available in large quantities and study their effect on the dissolving grade softwood pulp, especially on its alkaline solubility. All the studied cellulases had endoglucanse activity and they decreased the intrinsic viscosity of the pulp. The degradation of cellulose into solubilised sugars increased with the cellulases containing also cellobiohydrolases. The monocomponent endoglucanases enhanced alkaline solubility of the pulp more than the multicomponent cellulases and produced alkaline solutions with higher fluidity. The studies showed that the type of the cellulases in the enzyme mixture has significant effect on the amount of solubilised sugars during the enzyme treatment and on the alkaline solubility of the pulp.

The effects of hemicellulose removal from bleached birch kraft pulp by alkaline extraction with sodium hydroxide on the dielectric, electrical and electrostatic properties of paper material have been examined. The hemicellulose content, particularly the xylan content, of birch kraft pulp has an effect on the dielectric constant and on the dielectric loss factor. The real part of the dielectric constant increases with decreasing content of hemicellulose in papers containing the extracted birch kraft pulp. Hemicellulose removal by alkaline extraction increases the direct and alternating current electrical conductivity and changes the electrostatic properties of the paper. Dielectric relaxation spectra at different temperatures analysed using the Havriliak–Negami relaxation model revealed that the dielectric properties are determined by at least two relaxation processes which are affected by the hemicellulose content. The first relaxation process originates in the polarizable groups of cellulose and hemicellulose and the second is attributed to the water–polymer structures formed during the interaction of cellulose and hemicelluloses with moisture. Both relaxation processes are compared quantitatively.

The convertibility of paperboard in a press-forming process was studied using a novel type of tool set that allows forming of small substrates such as laboratory handsheets (i.e. experimental materials) to investigate the role of mold design on substrate-press-tool interaction. The tool set makes it possible to prepare rectangular trays in both sliding and fixed blank modes in a pilot-scale press-forming machine. The tests showed that the fixed-blank mode makes it possible to estimate the elongation of the substrate in the forming process by determining the maximum forming depth for rupture-free samples. A more detailed inspection with an optical microscope of grid-patterned materials revealed that elongation took place mostly on the rim area in addition to the tray wall, and that the outer dimensions of the blank remained practically unchanged. The behavior of the material in press forming process was evaluated in addition to the novel tool set in a bigger, production-scale mold, and results showed good agreement between the small tool set and the standard mold, in spite of the dimensional differences. The smaller size of the mold did not require a compromise in any aspect of the press-forming process.

In this study, the effect of enzyme treatment on refined, never-dried bleached birch kraft pulp was investigated, using an endo-1,4-β-xylanase, that is substantially free from cellulase activity. The xylanase treatment of refined never-dried pulp revealed a rapid initial hydrolysis rate with a time-dependent saturation level in the amount of hydrolyzed pulp carbohydrates. Surprisingly short xylanase treatment times were found to have an impact on the fiber surface structure and on the physicochemical properties of kraft pulp fibers. Xylanase treatment led to mild microscopic differences in the ultrastructure of a never-dried fiber, whereas local topographical differences were distinguishable with atomic force microscopy. Results from the analysis of dissolved carbohydrates and the interfacial properties of the xylanase-treated never-dried fibers thus confirm a selective removal of xylan from the fiber surfaces. The zeta-potential charge and dewatering properties of the pulp slurry, fiber morphology, and strength properties of the paper were affected, which is a concomitant of xylanase treatment. However, the papermaking properties of the fibers were mainly preserved with simultaneous improvement in the dewatering rate of the pulp. Thus, optimized xylanase treatment of refined bleached kraft pulp provides a fiber for papermaking or fiber modification purposes with a selectively modified chemical composition of the fiber surface layer.

In this scale-up study, we examined the effects of using varying amounts of fibers with reduced xylan content in paper. Bleached birch kraft pulp was partially or fully replaced by alkali-extracted pulp, and the effects of this replacement on the wet end chemistry of the paper machine and the resulting paper properties were determined. Our results show that paper properties can be maintained or improved when optimizing the partial replacement of bleached birch kraft pulp with alkali-extracted pulp. The incorporation of alkali-extracted pulp in paper machine stock had a positive effect on first pass retention and retention of chemicals. However, careful optimization of chemical dosages is required because of the altered charge balance in the wet end.

The use of a new, technical, high-purity magnesium hydroxide-based peroxide bleaching additive was evaluated in full mill-scale trial runs on two target brightness levels. Trial runs were conducted at a Finnish paper mill using Norwegian spruce (Picea abies) as the raw material in a conventional pressurized groundwood process, which includes a high-consistency peroxide bleaching stage. On high brightness grades, the use of sodium-based additives cause high environmental load from the peroxide bleaching stage. One proposed solution to this is to replace all or part of the sodium hydroxide with a weaker alkali, such as magnesium hydroxide. The replacement of traditional bleaching additives was carried out stepwise, ranging from 0% to 100%. Sodium silicate was dosed in proportion to sodium hydroxide, but with a minimum dose of 0.5% by weight on dry pulp. The environmental effluent load from bleaching of both low and high brightness pulps was significantly reduced. We observed a 35% to 48% reduction in total organic carbon (TOC), 37% to 40% reduction in chemical oxygen demand (COD), and 34% to 60% reduction in biological oxygen demand (BOD7) in the bleaching effluent. At the same time, the target brightness was attained with all replacement ratios. No interference from transition metal ions in the process was observed. The paper quality and paper machine runnability remained good during the trial. These benefits, in addition to the possibility of increasing production capacity, encourage the implementation of the magnesium hydroxide-based bleaching concept.

The runnability and convertibility of biopolymer dispersion–coated paperboard were determined using a novel adjustable packaging line equipped with a tray-pressing mould. Commercial paperboard was dispersion barrier coated on the back-side using a dual polymer system containing both a synthetic and a renewable biopolymer, of which the latter was the main component in the dispersion. The effect of the addition of a high-aspect-ratio platy pigment and synthetic polymer on both the grease resistance and the convertibility of the product was evaluated in addition to the evaluation of runnability and crack resistance in tray pressing and die cutting. The addition of synthetic polymer into bio-based dispersion improved the elastic properties, plasticity and, subsequently, mechanical convertibility of the product. Moderate additions of the synthetic polymer provided improved grease resistance for the biopolymer coatings. It revealed that the addition of synthetic polymer was sufficient in providing improved barrier properties, although the chemical compatibility and process window for the convertibility need to be considered. In addition to mechanical stability, the heat stability of the substrate needs to be investigated. Copyright © 2013 John Wiley & Sons, Ltd.

Three different commercial β-1,4-endoxylanase preparations were used to hydrolyze bleached kraft pulp. Xylo-oligosaccharides in the produced filtrates were separated and quantified using both high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). All the determinations were performed without sample derivatization. The analytical methods were used to highlight the differences between the enzymes behaviour in terms of hydrolysates, but also to estimate the productivity of xylo-oligosaccharides from kraft pulp when the bleached material would be used in biorefining industry. The research showed that the glycosyl hydrolase family 10 enzyme produced by Aspergillus oryzae released xylobiose and xylotriose from the pulp material. The major oligosaccharides released by the family 11 enzyme produced by Bacillus sp. were xylotriose, xylobiose and xylotetraose. On the contrary, another family 11 enzyme produced by A. oryzae produced also xylose. The HPLC results agreed well with the xylose concentrations obtained after acid hydrolysis. The CE data showed the same trend, but much lower concentrations were identified than with HPLC. At the same time the HPLC method was able to separate only small oligosaccharides, whereas CE could be used for separation of all the xylo-oligosaccharides from xylobiose to xylohexaose. The highest xylo-oligosaccharide yield was achieved with Shearzyme at pH 5 corresponding to 22 % of total xylan from bleached birch kraft pulp.

The polarization phenomenon of papers containing different amounts and different types of inorganic fillers during corona charging was studied using a dose-charging method. This method enables to investigate the phenomena in the conditions close to the real ones. It revealed that the paper composition affects the polarization tendency during the corona charging of paper. The filler influences the paper's dielectric constant and hence its electrical capacitance, charging potential and polarizing electric field. It was shown that paper polarization depends mainly on the electric field and this is caused by the orientation polarization and the role of the filler origin and its concentration in the polarization was surprisingly low. Polarization temperature dependences enable to propose the paper polarization mechanism. Paper polarizability is dominated by cellulose and the moisture content in it, and the liability of cellulose and hydrogen bonds hydroxyl groups.

A process for producing microfibrillated cellulose comprises providing a slurry comprising cellulosic fibers, treating the slurry with an enzyme, mechanically treating the slurry so that the fibers are disintegrated wherein the mechanical treatment and the treatment with the enzyme is performed simultaneously in a single treatment step. In this way it is possible to produce microfibrillated cellulose (MFC) in an improved and energy efficient way. A microfibrillated cellulose is produced according to the process.Patent family as of 4.4.2022AU2010269896 AA 20120209 AU20100269896 20100623 AU2010269896 BB 20150917 AU20100269896 20100623 AU2010269912 AA 20120209 AU20100269912 20100702 AU2010269912 BB 20160114 AU20100269912 20100702 BR112012000142 A2 20201027 BR20121100142 20100702 BR112012000142 A8 20201124 BR20121100142 20100702 BR112012000142 B1 20210518 BR20121100142 20100702 BR112012000143 A2 20161101 BR20121100143 20100623 BR112012000143 B1 20190806 BR20121100143 20100623 CA2767290 AA 20110113 CA20102767290 20100702 CA2767290 C 20170124 CA20102767290 20100702 CA2767304 AA 20110113 CA20102767304 20100623 CA2767304 C 20170110 CA20102767304 20100623 CL2012000040 A1 20120713 CL20120000040 20120106 CL52943 B 20160829 CL20120000040 20120106 CL2012000053 A1 20120713 CL20120000053 20120106 CN102472014 A 20120523 CN201080030879 20100623 CN102472013 A 20120523 CN201080030882 20100702 CN102472013 B 20180406 CN201080030882 20100702 CN105755884 A 20160713 CN201610122522 20100623 DE602010035440 D1 20160922 DE201060035440T 20100623 DE602010036272 D1 20161020 DE201060036272T 20100702 EP2452014 A1 20120516 EP20100796795 20100623 EP2452014 A4 20131120 EP20100796795 20100623 EP2452014 B1 20160810 EP20100796795 20100623 EP2452013 A1 20120516 EP20100796796 20100702 EP2452013 A4 20131120 EP20100796796 20100702 EP2452013 B1 20160907 EP20100796796 20100702 IN05254KN2011 A 20160826 IN2011KN05254 20111230 IN05257KN2011 A 20160826 IN2011KN05257 20111230 JP2012533000 T2 20121220 JP20120519087T 20100623 JP5719359 B2 20150520 JP20120519087T 20100623 JP2012532952 T2 20121220 JP20120519095T 20100702 KR101715428 B1 20170310 KR20127002536 20100702 KR20120093144 A 20120822 KR20127002536 20100702 KR20120098994 A 20120906 KR20127002537 20100623 PL2452014 T3 20170428 PL20100796795T 20100623 PL2452013 T3 20170228 PL20100796796T 20100702 RU2012103990 A 20130820 RU20120103990 20100702 RU2530022 C2 20141010 RU20120103990 20100702 RU2012104000 A 20130820 RU20120104000 20100623 RU2528394 C2 20140920 RU20120104000 20100623 SE200950534 A1 20101012 SE20090050534 20090707 SE533510 C2 20101012 SE20090050534 20090707 US2012160433 AA 20120628 US20100382573 20100702 US8778134 BB 20140715 US20100382573 20100702 US2012136146 AA 20120531 US20100382662 20100623 WO11004284 A1 20110113 WO2010IB52850 20100623 WO11004300 A1 20110113 WO2010IB53043 20100702 ZA201200327 A 20120926 ZA20120000327 20120116 ZA201200329 A 20120926 ZA20120000329 20120116 Link to current patent family on right

In this pilot scale study, we examined the effects of alkaline extraction time on xylan removal, pulp and paper properties, and the consequences that need to be addressed when scaling up and intensifying the process. Alkaline extraction of bleached birch kraft pulp yields two fractions: pure polymeric xylan and pulp with reduced xylan content. Our results indicate that a similar amount of xylan can be extracted in 5 min as the amount obtained in 60 min. We found, however, that the shorter extraction time is beneficial to maintain the fiber and paper properties at an acceptable level. This pilot trial demonstrated that the washing procedure of the alkali-treated fibers must be selected with care to avoid causing mechanical damage to fibers and to avoid the loss of fines.

There is a wide range of materials that can be considered as nonwoven random networks of fibres. Such materials include glass-fibre mats, filters, various paper products and structural components of cells and tissues. The mechanical properties of these kinds of networks have been studied extensively for many decades. As many of such networks form more or less two-dimensional structures, they can, to a good approximation, be considered to consist of randomly distributed fibres or filaments connected at their crossings points. Recent development of the resolution of X-ray computed tomography have enabled imaging of the three dimensional structure of such materials with a resolution sufficient to produce accurate information of the fibre network. As the mean segment length, for given elastic properties of the fibers and contacts in the network, essentially affects the elastic response of the network, it is a property of great practical importance, but it has been very difficult to determine. We therefore introduce a method to determine in practice the mean segment length along with the density of fiber-fiber contacts.

To clarify the influence of prehydrolysis on fiber characteristics, Scots pine (Pinus sylvestris L.) wood chips were subjected to pressurized hot-water and dilute-acid prehydrolysis (0.5% H2SO4) prior to kraft pulping to partially remove hemicelluloses as hydrolyzate. After the prehydrolysis, the wood chips were submitted to kraft pulping and the pulp was fully bleached in oxygen (O), chlorine dioxide (D), alkaline extraction (E) and chlorine dioxide (D)-sequence. Measurements with an automated optical fiber analyzer showed that prehydrolysis prior to kraft pulping caused significant changes in the fiber dimensions and morphology of the final bleached pulp. Especially, a decrease in fiber width and an increase in fiber deformations were observed compared to a reference kraft pulp. The scanning electron microscopy of handsheets supported the morphology analyses and revealed alterations also in the fiber ultrastructure. The changes in both chemical and physical fiber characteristics require attention when considering the correct processing and end-use of prehydrolysis-kraft pulp fibers.

The dynamic mechanical properties of coated offset paper before and after application of isopropyl alcohol and surfactant solutions have been investigated. The mechanical properties of the papers were studied with dynamical mechanical analysis in the tensile mode and the samples were submitted to a uniaxial loading in stress–strain measurements. An increase in the isopropyl alcohol concentration slightly reduced the mechanical strength, while the addition of surfactant clearly made the paper stiffer and weakened the paper strength. As the surface tensions of the liquids were adjusted to the same level, the changes in mechanical properties are ascribed to changes in water-induced wetting and subsequent changes in interfacial properties within the paper constituents. The storage and loss moduli of the paper after application of the surfactant solutions were twice those recorded after isopropyl alcohol treatment. The binder was not affected by the solutions, but there was significant debonding, disrupting th...

Scanning probe microscopy (SPM) was used for studying the changes in topographical, chemical, thermal and electrostatic properties of a styrene-butadiene latex coating as a function of annealing time. Changes in local surface properties obtained with SPM were correlated with changes in surface chemistry measured by time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and contact angle measurements. The studied copolymer film goes through chemically and topographically meta-stable transition states during thermal annealing, reaching a steady state only after a significant annealing time (21 h). The differences in surface chemistry of the meta-stable states appeared as characteristic thermal and electrostatic properties of the latex coating. The results on film formation and drying are discussed in light of existing literature and theories. In this transition stage, the surface concentrations of polymeric components show unstable behavior, accordingly shifting the thermal transitions. Furthermore, the drying of the surface and desorption of surfactants is affecting the surface charge balance, changing from negative to positive. This was attributed to the change of balance of ionic components on the surface.

A dosed charging–discharging method was applied to an investigation of the paper charging properties which may be important in toner transfer in electrophotographic printers and copiers. This investigation method, which is new for paper substrates, made it possible to reveal some characteristics of paper charging and discharging processes: the dependence of charge acceptance on charging intensity, which is different for coated and uncoated papers, the change in paper charging properties during charging, unconventional charge acceptance and potential decay dependence on thickness at higher relative humidity, and the role of paper polarization in the discharge of paper.