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  • 1.
    Alimadadi, Majid
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    3D-oriented fiber networks made by foam forming2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, ISSN 1572-882X, Vol. 23, no 1, 661-671 p.Article in journal (Refereed)
    Abstract [en]

    In industrial applications, such as paper and nonwovens, cellulose fibers are used in the form of a network where the fibers are oriented more or less in the sheet-plane direction. However, in many biological systems, fibers are instead oriented in a three-dimensional (3D) space, creating a wide variety of functionalities. In this study we created a 3D-oriented fiber network on the laboratory scale and have identified some unique features of its structure and mechanical properties. The 3D fiber network sheets were prepared by using foam-forming as well as modifying consolidation and drying procedures. The fiber orientation and tensile/compression behavior were determined. The resulting sheets were extremely bulky (above 190 cm3/g) and had extremely low stiffness (or high softness) compared to the reference handsheets. Despite this high bulk, the sheets retained good structural integrity. We found that a 3D-oriented fiber network requires much less fiber-fiber contact to create a connected (“percolated”) network than a two-dimensionally oriented network. The compression behavior in the thickness direction was also unique, characterized by extreme compressibility because of its extreme bulk and a long initial increase in the compression load as well as high strain recovery after compression because of its fiber reorientation during compression.

  • 2.
    Alimadadi, Majid
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Exploring One-more Dimension of Paper: Properties of 3D-Orieneted Fiber Network2014In: Progress in Paper Physics Proceedings 2014, 2014Conference paper (Other academic)
  • 3.
    Andersson, Kerstin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Pranovich, Andrey
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Eriksson, Marie
    Holmbom, Bjarne
    Effects of biological treatment on the chemical structure of dissolved lignin-related substances in effluent from thermomechanical pulping2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 23, no 2, 164-171 p.Article in journal (Refereed)
    Abstract [en]

    Effluent from a TMP-based pulp and paper mill was collected at the inlet and outlet of the mill's biological treatment plant and fractionated by sorption on XAD-8 resin and MTBE precipitation. Fractionation indicated that the refractory dissolved organic material in biologically treated effluent was mainly composed of lignin-related substances. Characterisation of the lignin-related substances by chromatographic and spectrometric methods confirmed the similarities of the isolated material and milled wood lignin. Fractionation and characterisation of alkali-extracted material from solids (biosludge) in biologically treated effluent found evidence of lignin-related material. Results indicated that biological treatment had altered the chemical structure and molar-mass distribution of dissolved lignin-related substances.

  • 4.
    Andersson, Stefan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Low consistency refining of mechanical pulp: process conditions and energy efficiency2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis is focussed on low consistency (LC) refining of mechanical pulp. Theresearch included evaluations of energy efficiency, development of pulpproperties, the influence of fibre concentration on LC refining and effects of rotorposition in a two-zoned LC refiner.

    Trials were made in mill scale in a modern TMP line equipped with an MSDImpressafiner for chip pre-treatment, double disc (DD) first stage refining and aprototype 72-inch TwinFlo LC refiner in the second stage. Tensile index increasedby 8 Nm/g and fibre length was reduced by 10 % in LC refining at 140 kWh/adtgross specific refining energy and specific edge load 1.0 J/m. Specific lightscattering coefficient did not develop significantly over the LC refiner.

    The above mentioned TMP line was compared with a two stage single disc highconsistency Twin 60 refiner line. The purpose was to evaluate specific energyconsumption and pulp properties. The two different process solutions were testedin mill scale, running similar Norway spruce wood supply. At the same tensileindex and freeness, the specific energy consumption was 400 kWh/adt lower in theDD-LC concept compared with the SD-SD system. Pulp characteristics of the tworefining concepts were compared at tensile index 47 Nm/g. Fibre length was lowerafter DD-LC refining than after SD-SD refining. Specific light scattering coefficientwas higher and shive content much lower for DD-LC pulp.

    The effects of sulphite chip pre-treatment on second stage LC refining were alsoevaluated. No apparent differences in fibre properties after LC refining werenoticed between treated and untreated pulps. Sulphite chip pre-treatment iniiicombination with LC refining in second stage, yielded a pulp without screeningand reject refining with tensile index and shives content that were similar to nonpre-treated final pulp after screening and reject refining.

    A pilot scale study was performed to investigate the influence of fibreconcentration on pulp properties in LC refining of mechanical pulps. MarketCTMP was utilised in all trials and fibre concentrations were controlled by meansof adjustments of the pulp consistency and by screen fractionation of the pulp. Inaddition, various refiner parameters were studied, such as no-load, gap and baredge length. Pulp with the highest fibre concentration supported a larger refinergap than pulp with low fibre concentration at a given gross power input. Fibreshortening was lower and tensile index increase was higher for long fibre enrichedpulp. The results from this study support the interesting concept of combiningmain line LC refining and screening, where screen reject is recycled to the LCrefiner inlet.

    It has been observed that the rotor in two-zoned refiners is not always centred,even though pulp flow rate is equal in both refining zones. This leads to unequalplate gaps, which renders unevenly refined pulp. Trials were performed in millscale, using the 72-inch TwinFlo, to investigate differences in pulp properties androtor positions by means of altering the pressure difference between the refiningzones. In order to produce homogenous pulp, it was found that uneven plate gapscan be compensated for in LC refiners with dual refining zones. Results from thedifferent flow rate adjustments indicated that the control setting with similar plategap gave the most homogenous pulp.

  • 5.
    Andersson, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Sandberg, Christer
    Holmen Paper AB, Braviken Paper Mill, SE-60188 Norrkoping, Sweden .
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Comparison of mechanical pulps from two stage HC single disc and HC double disc - LC refining2012In: Appita journal, ISSN 1038-6807, Vol. 65, no 1, 57-62 p.Article in journal (Refereed)
    Abstract [en]

    A mechanical pulping line consisting of high consistency (HC) double disc (DD) and low consistency (LC) refining was compared with a two stage single disc (SD) high consistency twin refiner line. The purpose of this study was to evaluate specific energy consumption and pulp properties. The two different process solutions were tested running similar Norway spruce wood supply. At similar tensile index and freeness, the DD-LC concept reduced the electric energy consumption by 400 kWh/adt compared with the traditional two-stage SD-SD system. Pulp characteristics of the two refining concepts were compared at tensile index 47 Nm/g. Fibre length was reduced more after DD-LC refining than after SD-SD refining. Specific light scattering coefficient was higher after DD-LC refining than SD-SD refining, while the development in second stage refining was better for SD-SD pulp than for DD-LC pulp. Shive level was significantly lower for DD-LC pulp than for SD-SD pulp.

  • 6.
    Andersson, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Effect of fibre length distribution on low consistency refining of mechanical pulpManuscript (preprint) (Other academic)
  • 7.
    Andersson, Stefan
    et al.
    Holmen Paper AB, Bravikens Pappersbruk, SE-601 88 Norrköping, Sweden.
    Sandberg, Christer
    Holmen Paper AB, Bravikens Pappersbruk, SE-601 88 Norrköping, Sweden.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Effect of long fibre concentration on low consistency refining of mechanical pulp2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 4, 702-706 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the influence of long fibre concentration on loadability and pulp properties during LC refining of mechanical pulp. Long fibre concentration was adjusted to three different levels by screen fractionation of the pulp. The three pulps were refined in a single disc pilot scale LC refiner at similar process conditions. Increased long fibre concentration supported a larger refiner gap and resulted in less fibre cutting at a given specific energy consumption. The higher long fibre concentration probably contributed to a stronger fibre network that maintained a larger refining gap at certain specific energy consumption. Increased long fibre concentration also enabled a higher tensile index increase in the LC refiner at certain fibre length reduction. The study supports a process combining LC refining with screen fractionation, where the long fibre fraction is recycled to the refiner feed. This enables a higher loadability and a more effective utilisation of the LC refiner. By using this technology, overall specific energy consumption can be reduced if a larger share of the refining is performed in LC rather than HC refining.

  • 8.
    Andersson, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    The effect of rotor position on pulp properties in a two-zoned low consistency refiner2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 3, 525-530 p.Article in journal (Refereed)
    Abstract [en]

    Earlier studies have shown that plate gaps are sometimes unequal in two-zoned low consistency refiners and that unequal gaps render unevenly refined pulp. It is also known that optimisation of plate gap in low consistency refining leads to improved energy efficiency. In this work, trials were made in mill scale in a modern TMP line equipped with a prototype 72 inch TwinFlo low consistency refiner in second stage. The study was designed to investigate the development of pulp properties from different rotor positions by means of altering the outlet flow rate ratio. The specific energy consumption was calculated for each refining zone and setting, based on flow rate and temperature increase. In order to produce homogenous pulp, it was found that uneven plate gaps need to be compensated in low consistency refiners with dual refining zones. Results from the different flow rate adjustments indicated that the control setting with similar plate gap gave the most homogenous pulp. However, further studies are needed to find an adequate rotor control strategy. The temperature increase in each refining zone seems to correlate well with the applied specific energy consumption in each refining zone.

  • 9. Andreasson, B
    et al.
    Forsström, Jennie
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wågberg, Lars
    Determination of fibre pore structure: influence of salt, pH and conventional wet strength resins2005In: Cellulose (London), ISSN 0969-0239, Vol. 12, no 3, 253-265 p.Article in journal (Refereed)
    Abstract [en]

    It has been shown, in the present investigation, that the two methods used to investigate the pore size distribution of unbleached chemical pulps, i.e. inverse size exclusion chromatography (ISEC) and nuclear magnetic resonance (NMR), give different average pore radius for the pores inside the fibre wall. This is due to the way in which these experiments are performed and the sensitivity of the methods to different types of pores in the cell wall. It was also shown that the two methods gave different results when changing the pH and the ionic strength of the pulp suspension. The pore radius, as detected with ISEC, decreased with both increasing ionic strength and decreasing pH, indicating a loose structure of the exterior of the fibrillar network. However, the pore radius as detected with NMR, was virtually unaffected when increasing the ionic strength, indicating a very rigid structure of the interior of the fibre wall. Decreasing pH though, lead to a decrease in pore radius indicating that upon protonation of the carboxylic groups in the fibre wall, the electrostatic repulsion is diminished and the average pore radius decreases. The NMR technique was also used to study wet strength aid penetration into the fibre wall. It was shown that wet strength aids with a small molecular weight, penetrated the fibre wall, as detected by a decrease in pore radius. It was also shown that addition of different wet strength aids increased the tensile index of the sheet and decreased the fibre strength, measured as zero span-strength of the sheets.

  • 10.
    Bohlin, Erik
    et al.
    Karlstad Universitet.
    Gustafsson Coppel, Ludovic
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Johansson, Caisa
    Karlstads Universitet.
    Edström, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Modelling of brightness decrease in coated cartonboard as an effect of calendering: Microroughness and effective refractive index aspects2010In: 11th Advanced Coating Fundamentals Symposium Proceedings: The Latest Advances in Coating Research and Development, Norcross, GA, USA: TAPPI Press, 2010, 51-65 p.Conference paper (Refereed)
    Abstract [en]

    Calendering of coated paper leads to a brightness decrease. The mechanism for this is not clear, although it has been discussed in the past. One common explanation is that the porosity of the coating layer decreases and hence scattering. By comparing simulated and measured results this paper shows that modifications of the surface properties account for the brightness decrease of GCC coated substrates with calendering. The effect of a deformable cartonboard substrate is investigated here and compared to a less deformable plastic film substrate. From simulations based on a two-layer Kubelka-Munk model, it is shown that the brightness decrease of the cartonboard due to calendering has a negligible contribution to the brightness decrease of the coated cartonboard. The brightness decrease was similar for coated plastic film and coated cartonboard. The thickness of GCC coated plastic films was not affected by calendering irrespectively of the pigment and latex size distribution. Monte Carlo light scattering simulations, taking into account the measured decrease of surface microroughness and increased effective refractive index, showed that surface modifications accounted for most of the observed brightness decrease of the GCC coated substrate, whereas the bulk scattering and absorption coefficients were not affected by calendering. It is also shown that the scattering coefficient is significantly dependent on the coat weight whereas the physical absorption coefficient is not.

  • 11. Bäckström, Marie
    et al.
    Hammar, Lars-Åke
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Beatability and runnability studies of ion-exchanged unbleached kraft pulps on a pilot scale2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 1, 94-100 p.Article in journal (Refereed)
    Abstract [en]

    It has earlier been shown that the counter-ion to the charged groups in the fibre has a significant effect on the beatability of fibres, but large-scale investigations of this effect are scarce in the literature. The objectives of the present study were therefore to develop a technique to ion-exchange large quantities of industrial pulp into the Na+-form using complexing agents and to study the effect of industrial-scale refining on pulp fibres in the Na+-form and how the fibres respond to industrial-like papermaking. The results show that ion-exchange can indeed be conducted on a pilot-scale using complexing agents such as DTPA. The study further indicates that an energy reduction of 50% at a given WRV or tensile index may be achieved if the fibres are converted to Na+-form prior to pilot-scale refining. By applying these techniques in full-scale production, it should thus be possible to save significant amount of energy, especially in the case of papers made from unbleached pulp that usually demands a higher degree of beating to achieve sufficient strength.

  • 12.
    Dahlström, Christina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Quantitative microscopy of coating uniformity2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Print quality demands for coated papers are steadily growing, and achieving coating uniformity is crucial for high image sharpness, colour fidelity, and print uniformity. Coating uniformity may be divided into two scales: coating thickness uniformity and coating microstructure uniformity, the latter of which includes pigment, pore and binder distributions within the coating layer. This thesis concerns the investigation of both types of coating uniformity by using an approach of quantitative microscopy.First, coating thickness uniformity was analysed by using scanning electron microscope (SEM) images of paper cross sections, and the relationships between local coating thickness variations and the variations of underlying base sheet structures were determined. Special attention was given to the effect of length scales on the coating thickness vs. base sheet structure relationships.The experimental results showed that coating thickness had a strong correlation with surface height (profile) of base sheet at a small length scale. However, at a large length scale, it was mass density of base sheet (formation) that had the strongest correlation with coating thickness. This result explains well the discrepancies found in the literature for the relationship between coating thickness variation and base sheet structure variations. The total variance of coating thickness, however, was dominated by the surface height variation in the small scale, which explained around 50% of the variation. Autocorrelation analyses were further performed for the same data set. The autocorrelation functions showed a close resemblance of the one for a random shot process with a correlation length in the order of fibre width. All these results suggest that coating thickness variations are the result of random deposition of particles with the correlation length determined by the base sheet surface textures, such as fibre width.In order to obtain fundamental understandings of the random deposition processes on a rough surface, such as in paper, a generic particle deposition model was developed, and systematic analyses were performed for the effects of particle size, coat weight (average number of particles), levelling, and system size on coating thickness variation. The results showed that coating thickness variation3grows with coat weight, but beyond a certain coat weight, it reaches a plateau value. A scaling analysis yielded a universal relationship between coating thickness variation and the above mentioned variables. The correlation length of coating thickness was found to be determined by average coat weight and the state of underlying surfaces. For a rough surface at relatively low coat weight, the correlation length was typically in the range of fibre width, as was also observed experimentally.Non-uniformities within the coating layer, such as porosity variations and binder distributions, are investigated by using a newly developed method: field emission scanning electron microscopy (FESEM) in combination with argon ion beam milling technique. The combination of these two techniques produced extremely high quality images with very few artefacts, which are particularly suited for quantitative analyses of coating structures. A new evaluation method was also developed by using marker-controlled watershed segmentation (MCWS) of the secondary electron images (SEI).The high resolution imaging revealed that binder enrichment, a long disputed subject in the area, is present in a thin layer of a 500 nm thickness both at the coating surface and at the base sheet/coating interface. It was also found that the binders almost exclusively fill up the small pores, whereas the larger pores are mainly empty or depleted of binder.

  • 13.
    Dahlström, Christina
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Allem, Rafik
    FPInnovations, Pointe Claire, PQ, Canada.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    New Method for Characterizing Paper Coating Structures Using Argon Ion Beam Milling and Field Emission Scanning Electron Microscopy2011In: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 241, no 2, 179-187 p.Article in journal (Refereed)
    Abstract [en]

    We have developed a new method for characterizing microstructures of paper coating using argon ion beam milling technique and field emission scanning electron microscopy. The combination of these two techniques produces extremely high-quality images with very few artefacts, which are particularly suited for quantitative analyses of coating structures. A new evaluation method has been developed by using marker-controlled watershed segmentation technique of the secondary electron images. The high-quality secondary electron images with well-defined pores makes it possible to use this semi-automatic segmentation method. One advantage of using secondary electron images instead of backscattered electron images is being able to avoid possible overestimation of the porosity because of the signal depth. A comparison was made between the new method and the conventional method using greyscale histogram thresholding of backscattered electron images. The results showed that the conventional method overestimated the pore area by 20% and detected around 5% more pores than the new method. As examples of the application of the new method, we have investigated the distributions of coating binders, and the relationship between local coating porosity and base sheet structures. The technique revealed, for the first time with direct evidence, the long-suspected coating non-uniformity, i.e. binder migration, and the correlation between coating porosity versus base sheet mass density, in a straightforward way.

  • 14.
    Dahlström, Christina
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Andres, Britta
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Forsberg, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Coating Uniformity and its Effect on Supercapacitor Capacitance2014Conference paper (Other academic)
  • 15.
    Edström, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Radiative transfer i pappersindustriella tillämpningar2010In: Thule: Kungl. Skytteanska Samfundets Årsbok 2010 / [ed] R. Jacobsson, Umeå: Kungl. Skytteanska Samfundet , 2010, 115-124 p.Chapter in book (Other academic)
  • 16.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Papermaking Research symposium (PRS): Web tension variations and runnability of the open draw section2009In: PRS 2009 Papermaking Research Symposium, Kuopio, 2009, , 11 p.Conference paper (Refereed)
  • 17.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    System dynamics of the open draw with web adhesion: Particle approach2010In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 77, no 2, 1-11 p.Article in journal (Refereed)
    Abstract [en]

    In the present work we propose a particle approach, which is designed

    to treat complex mechanics and dynamics of the open-draw sections that

    are still present in many of today's paper machines. First, known

    steady-state continuous solutions are successfully reproduced. However,

    it is shown that since the boundary conditions depend on the solution

    itself, the solutions for web strain and web path in the open-draw

    section are generally time-dependent. With a certain set of system

    parameters, the nonsteady solutions are common. A temporal fluctuation

    of Young's modulus, for example, destabilizes the system irreversibly,

    resulting in the continuous growth of web strain, i.e., break. Finally

    we exemplify with some strategic draw countermeasures how to prevent a

    dangerous evolution in the web strain.

     

  • 18.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    System stability of the open draw section and paper machine runnability2009In: ADVANCES IN PULP AND PAPER RESEARCH, OXFORD 2009, VOLS 1-3 / [ed] IAnson, SJ, 2009, 557-575 p.Conference paper (Refereed)
    Abstract [en]

    The present work is concerned with the system dynamics and stability of the open draw sections of paper machines where web breaks occur most frequently. We have applied a novel particle-based system dynamics model that allows the investigation of complex interactions between web property fluctuations and system parameters, without any constraints of a particular geometrical web shape or boundary conditions assumed a priori. The result shows that, at a given machine draw and web property parameters, the open draw section maintains its steady-state until it reaches a certain machine speed limit. At this speed the system looses its stability and the web strain starts growing without any limit, and thus leading to a web break. A similar instability can also be triggered when web properties suddenly fluctuate during steady-state operation. The parametric sensitivity studies indicate that, among the web property parameters studied, the elastic modulus of the wet web has the largest impact on the critical machine speed as well as on the detachment point where the web is released from the first roll. Further analysis shows that the decrease in dryness has a (negative) synergistic effect causing an increased risk of system instability. It is, therefore, most important to control, not only average dryness, but also its variations in order to enhance paper machine runnability.

  • 19.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    The correlation between web breaks and defectsManuscript (preprint) (Other academic)
  • 20.
    Enberg, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Norske Skog Saugbrugs.
    Storage of Hydrogen Peroxide Bleached Mechanical Pulp: Reduction in Reflectance over the Visible Spectrum2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis is to determine possible causes of the darkening of hydrogen peroxide bleached mechanical pulp over the visible spectrum and their relative contributions. It focuses on both process conditions and the composition of the pulp and the dilution water, including additions or losses of material along the process line from the bleach tower to the paper machine.

    A mapping of the optical properties of the pulp along the process showed that the fine fraction of the pulp darkened more than the long fibre fraction. Simulation of retention times of different fractions showed that the main part of the fine material is retained in the paper within a few hours, a small part might circulate for considerably longer time and may therefore be strongly coloured.

    Storage trials were mainly performed using a hydrogen peroxide bleached mechanical pulp intended for SC paper made of Norway spruce (Picea abies), sampled on one occasion and stored in a freezer. Unwashed or well-washed pulp was stored in distilled water or in different process waters. Some complementary trials were included, e.g. unbleached pulp.

    Time and temperature were the process variables that gave the strongest darkening of the pulp, as expected, both in a clean and a more process-like system, whereas pH only had an effect in the presence of process waters; the highest brightness stability was seen at a pH around 5.5–6.0.

    The darkening was due to an increase in the light absorption coefficient (k) beginning at short wavelengths, but after longer storage times the increase in kλ also became noticeable at longer wavelengths. The colour (CIE L*, a*, b*) of the pulp changed towards red and yellow, initially more towards red and then more towards yellow. These changes were clearly visible.

    Washing of the bleached pulp made it less sensitive to storage; possibly due to the removal of extractives, lignin-like substances, metals and pulp fines. This washing had little effect before storage and the amount of material removed was small.

    The pulp darkened more when stored in process waters compared to distilled water. Apart from fibres, most of the colour was associated with pulp fines or filler but some colour was also found in the dissolved and colloidal fractions. At an increased pulp consistency, the increase in k460 was smaller.

    Storage in white water from the paper machine gave extensive discolouration with a shoulder in the absorption spectrum around 550–650 nm, which increased with time. The addition of ferric ions increased the light absorption coefficient during storage, but could not explain the increased absorption at 550–650 nm nor could it be the only cause of the darkening in the mill system. A cationic basic violet dye gave a shoulder in the absorption spectrum similar to that of the mill system, but the absorption of the dye did not increase during storage. Model calculations indicate, but do not prove, that ferric ions together with violet and red dyes could have played a major, but not exclusive role in the colour observed in the mill system after storage. The darkening not accounted for, at longer wavelengths and around 550–650 nm, is suggested to be related to fines and fillers including dissolved and colloidal substances associated with these particles.

    A method to produce representative sheets for determination of optical properties of mechanical pulps was developed. The new method makes it possible to follow changes in light absorption and light scattering coefficients over the visible range of wavelengths. It is approximately six times faster than standard methods, reduces the risk of additional darkening of the sample and can be used with small pulp quantities.

    The deviation from the expected linear behaviour of the light scattering coefficient, s, at wavelengths corresponding to strong light absorption has been studied using the Kubelka-Munk model and the angular resolved DORT2002 radiative transfer solution method. The decrease in s could not be explained by errors introduced in the Kubelka-Munk modelling by anisotropic scattering.

  • 21.
    Enberg, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Opdal, Øivind
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Øyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Rundlöf, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Capisco Sci & Art, SE-60234 Norrkoping, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Mapping and modelling of optical properties from pulp to super calendered paper2015In: Appita journal, ISSN 1038-6807, Vol. 68, no 2, 128-138- p.Article, review/survey (Refereed)
    Abstract [en]

    During production of mechanical pulp based paper, the pulp darkenswithin the process which represents a significant cost for the mill. Amapping of the optical properties of the pulp was conducted along theprocess, from pulp mill to paper machine, at a mill producing supercalendered (SC) paper on three paper machines. The focus was to evaluateat which positions in the mill the discolouration occurs and also whichfraction of the pulp darkens the most.The fine fraction of the pulp darkened more than the long fibrefraction. Bleached pulp diluted with white water from the paper machinedarkened more during storage than pulp diluted with clear filtrate. Thewhite water contains a considerable amount of suspended solids, i.e.pulp fines and clay. There was a tendency for a shoulder in absorptionspectra of the pulp stored in white water from the paper machine in theregion 550 to 650 nm, both for fibres and for fines. This is in the sameregion where the added dyes have their absorption maxima and also somecomplexes between iron and some of the components among lignin and theextractives. Simulation of retention times of different fractions showedthat, although the main part of the fine material is retained in thepaper within a few hours, a small part might circulate for considerablylonger time.

  • 22.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Energy efficient mechanical pulping – summary of the Scandinavian industry initiative research work 2011 - 20152016In: 2016 International Mechanical Pulping Conference, Jacksonville, Florida, USA  September 28-30, 2016: SESSION 11: INDUSTRY INITIATIVE FOR ENERGY REDUCTION / [ed] Robert Lanouette, Georgia 30092 USA: TAPPI Press, 2016, 288-303 p.Conference paper (Refereed)
    Abstract [en]

    A research program funded by the Swedish Energy Agency, the Swedish Knowledge Foundation and the Research Council of Norway was initiated by the companies; Holmen, Norske Skog, SCA and Stora Enso during 2008 with the objective to demonstrate techniques to reduce electrical energy demand by 50% for production of TMP and CTMP within a 10-year period starting 2011, while retaining similar final product characteristics of printing paper and paperboard. A gap analysis was performed to summarize different options to reach the goal at similar final product quality properties. The gap analysis indicated that some different approaches based on earlier research work both in pilot and demonstration scale together with improved process and product quality control should make it possible to reach the very tough goal. The very thorough benchmarking study was performed during 2012 including 16 TMP and CTMP-lines in Norway and Sweden showed the best production lines had the following electrical energy demands to certain final product properties; 900 kWh/t for CTMP optimized for paperboard, 1800 kWh/t for TMP optimized for newsprint and 2800 kWh/t for TMP optimized for SC-paper. The best results reached in industrial demonstration tests until 2015 showed potential to reduce the energy demand from 900 to 700 kWh/t for paperboard CTMP, from 1800 to 1400 kWh/t for newsprint TMP and from 2800 to 2400 for SC-paper TMP. In addition the results from other research within the program in the form of pilot and demonstration trials indicates that it could be possible to reach the goal of 50% reduced energy demand within a 10-year period provided that the industry and the research funds will continue to finance a continuation of the research program. 

  • 23.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hellström, Lisbeth
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sandström, Peter
    SCA Reseach.
    Liden, Joar
    SCA Ortviken.
    Söderberg, Mats
    SCA Research.
    Mats, Egnell
    Andritz Iggesund Tools.
    Improved refining energy efficiency in thermo-mechanical pulping by means of collimated wood chipping – from solid mechanics to full scale evaluation2016In: PaperWeek Canada 2016 Conference February 1 to 5, 2016, Montreal: Technical Track Program / [ed] Greg Hay, 2016Conference paper (Refereed)
    Abstract [en]

    The wood chipping process was never optimized with regard to high yield pulping processes as thermomechanical pulping (TMP) and chemithermomechanical pulping (CTMP). It is generally believed that wood chips for pulping should be produced in such a way that the degree of damage is minimized and that the chip dimensional distribution should be as narrow as possible. Since the TMP and CTMP processes were developed in the 60-ies and 70-ies, compression screw as well as roll nip equipment have been developed to pretreat wood chips as a way to reduce refining energy consumption to given fiber and pulp properties and also in order to improve impregnation. The general conclusions are that a combination of shear and compression in the tangential or radial direction of the wood initiates cracks that later in the refiner will enhance and optimize fiber separation and also fiber property development. The idea with the collimated chipping technology is to utilize the wood chipper as a tool, combining cutting of wood logs to wood chips with a pretreatment of the chips by creating cracks that would enhance fiber separation, fiber surface development as well as chip-impregnation. In this case the compression is performed in the wood fiber direction, in which direction wood actually is weakest when it comes to compression induced cracking. The maximization of the amount of cracks in wood-chips is performed by optimizing the knife angle (or spout angle) in the chipper, to what we call collimated chipping (according to a patent owned by CCT AB). This presentation describes a theoretical background and two demonstration scale studies performed by SCA Forest Products at their Ortviken mill. One conclusion drawn, based on two-month test period with three weeks of collimated chipping, was that specific refining energy reduction was around 100 kWh/adt of the 1400 kWh/adt used in primary stage double disc refining. Most probably the potential is higher if the whole system is optimized. Tests were performed at constant production rate and energy was reduced by reducing power to constant freeness, leading to similar tensile and light scattering levels. The deliberately increased forces created in the wood chipper by means of an optimized (increased) edge angle caused more problems with knife holder equipment than normally, as well as increased vibrations. These problems will have to be solved for future long-term implementation of the technique.

  • 24.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hammar, Lars Åke
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Method of reducing the energy consumption at the refining of cellulose containing material US 5007985 A1991Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.

  • 25.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hammar, Lars Åke
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Method of reducing the energy consumption at the refining of cellulose containing material US 5007985 A1991Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.

  • 26.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hammar, Lars Åke
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Method of reducing the energy consumption at the refining of cellulose-containing material EP 0302075 A11989Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The method of reducing the energy consumption in the refining / beating of a material containing cellulose consists of adding an alkali to the material to neutralize the acid groups bound to the fiber wall. According to the invention, the pH value in the pulp suspension is measured at the outlet of the refiner, alkali is added in an amount depending on the pH value measured for the neutralization without excess in the threshing zone or immediately before the material enters the latter in an amount between 0.05 and 9 kg / ton, preferably 0.5 to 5 kg / ton, more particularly between 1 and 4 kg / ton, the calculation being performed NaOH kilogram per ton of pulp.

  • 27.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hammar, Lars Åke
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Svensson, Börje
    Innventia (STFI).
    Method of making mechanical and chemi-mechanical papermaking pulp WO 1989010998 A11989Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The invention relates to a method of manufacturing mechanical and chemi-mechanical papermaking pulp with low energy input by disintegrating and beating wood material in at least two steps. According to the invention, the material is coarse-disintegrated in a first step at a concentration exceeding 20 %, acid groups in the wood material are neutralized, the material is diluted to a concentration of 1-10 % and beaten in one or several steps.

  • 28.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hammar, Lars Åke
    Innventia (STFI).
    Sjögren, Birger
    Innventia (STFI).
    Svensson, Börje
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    A method of producing cellulosic pulp EP 0500674 A11992Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Is produced from mechanical pulp and chemi-mechanical, in particular paper pulp, with a low energy input, by disintegrating and timber trituration in one or several steps. According to the invention, is added a substance capable of forming complexes with polyvalent metal ions, particularly calcium ions, called complexing agent, to the timber, before the crushing process, to replace said calcium ions or Another singular versatile metal with sodium ions, which further reduces the energy input.

  • 29.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hammar, Lars Åke
    Innventia (STFI).
    Sjögren, Birger
    STFI (Innventia).
    Svensson, Börje
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    A method of producing cellulosic pulp WO 1991006700 A11991Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Mechanical and chemimechanical cellulose pulp, particularly paper pulp, is produced at a low energy input by disintegrating and beating wood material in one or more stages. Acccording to the invention, a substance capable of forming complexes with polyvalent metal ions, particularly calcium ions, so-called complexing agent, is added to the wood material prior to the beating process in order to replace said calcium or other polyvalent metal ions with sodium ions, therewith a further reduction in the energy input is obtained.

  • 30.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hammar, Lars Åke
    Innventia (STFI).
    Pettersson, Rune
    STFI.
    Method of reducing the energy consumption at the refining of cellulose-containing material WO 1987006280 A11987Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg /ton, suitably 1-4 kg/ton, calculated as NaOH.

  • 31.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Hammar, Lars Åke
    Innventia (STFI).
    Method of reducing the energy consumption at the refining of cellulose containing material US 5007985: Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.1991Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.

  • 32.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Hammar, Lars Åke
    Innventia (STFI).
    Method of reducing the energy consumption at the refining of cellulose-containing material CA 1281856 C1991Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The invention relates to a method of reducing the energy consumption in the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutral-ization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, prererably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.

  • 33.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Johansson, B.
    Paper recycling2009In: Pulping Chemistry and Technology, Walter de Gruyter, 2009, 391-427 p.Chapter in book (Other academic)
  • 34.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Karlström, Anders
    Chalmers.
    System for continuously measuring pressure and temperature in the beating zone of refiners WO 1996014156 A11994Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    During refining/beating of beating material there exists a need to measure more parameters than the gap, directly in the beating zone. The present invention makes this possible and it relates to a system for continuous measuring of pressure and temperature in the beating zone and the system is characterized in that a number of separate/combined pressure sensors or temperature sensors provided with cables are applied on or in at least one of the homogeneous beating discs or, beating discs constructed of segments, of the refiner along the active radius of the beating disc, alternatively are arranged in at least one position between, alternatively between and in, two of the segments being present in the beating disc along the active radius of the beating disc and that the cables are collected into a bunch of cables or are transformed into another cable and leave the beating disc via a hole therein, if the beating disc is stationary, to be connected to a possible detecting unit and a subsequent presentation unit, alternatively, if the beating disc rotates, that the bunch of cables/the cable is connected to a collector shoe arranged against the shaft of the refiner with further connection according to the above.

  • 35.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Karlström, Anders
    Chalmers.
    System zur kontinuierlichen messung von druck und temperatur im zerkleinerungsbereich eines refinders1994Patent (Other (popular science, discussion, etc.))
  • 36.
    Engstrand, Per
    et al.
    Mid Sweden University.
    Karlström, Anders
    Nilsson, Lennart
    The impact of chemical addition on refining parameters1995In: International Mechanical Pulping Conference 1995, Ottawa/St Paul, Canada, Ottawa,: Ontario Technical Section, CPPA , 1995, 281-286 p.Conference paper (Other academic)
  • 37. Engstrand, Per
    et al.
    Lindgren, Johan
    Iggesund Paperboard AB.
    Agnemo, Roland
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    A method for increasing the stability of fluorescent whitening agent WO 2004050994 A12004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a method for increasing the stability of fluorescent whitening agent after its preparation and during its use either on its own or mixed with other chemicals. The method is characterised in that the whitening agent is supplied with an organic acid containing aromatic group and/or can be esterified internally forming lactone, or the salt of the acid (additive A) and reducing chemical (additive B).

  • 38.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Hammar, Lars Åke
    Innventia (STFI).
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Svensson, Börje
    Innventia (STFI).
    Method of making mechanical and chemi-mechanical papermaking pulp. EP 0413736 A11991Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The invention relates to a mechanical manufacturing process and chemical mechanical pulp with low energy input by disintegrating and refining material wood pile in at least two stages. According to the invention, the material undergoes a coarse disintegration in a first step at a concentration exceeding 20%, neutralized acid groups in the wood material, said material then diluted until a concentration of 1 to 10% and is refined in one or more steps.

  • 39.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hammar, Lars Åke
    Innventia (STFI).
    Svensson, Börje
    Innventia (STFI).
    Method of making mechanical and chemi-mechanical papermaking pulp CA 1320067 C1993Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The invention relates to a method of manufacturing mechanical and chemi-mechanical papermaking pulp by disintegrating and beating wood material in at least two steps. The material is coarse-disintegrated in a first step at a concentration exceeding 20%, acid groups in the wood material are neutralized, the mater-ial is diluted to a concentration of 1-10% and beaten in one or several steps. Under these conditions the total energy consump-tion is substantially reduced without reducing the yield and deteriorating the properties of the pulp.

  • 40.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Rune
    STFI.
    Htun, Myat
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hammar, Lars Åke
    Innventia (STFI).
    Svensson, Börje
    Innventia (STFI).
    Method of making mechanical and chemi-mechanical papermaking pulp EP 0413736 B11993Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The invention relates to a method of manufacturing mechanical and chemi-mechanical papermaking pulp with low energy input by disintegrating and beating wood material in at least two steps. According to the invention, the material is coarse-disintegrated in a first step at a concentration exceeding 20 %, acid groups in the wood material are neutralized, the material is diluted to a concentration of 1-10 % and beaten in one or several steps.

  • 41.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Jonsson, Jonas
    Holmen Paper AB.
    Starck, Göran
    Holmen Paper aB.
    Wahlgren, Mikael
    Holmen Paper AB.
    Wancke-Ståhl, Charlotte
    Method of producing bleached thermomechanical pulp (tmp) or bleached chemithermomechanical pulp (ctmp) EP 1407073 B12005Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    There is a need for a cheaper method of producing bleached TMP and CTMP without impairing the properties of the pulp. This is made possible by the present invention, which relates to a method of producing said pulps in which finely divided lignocellulosic material is defibrated after pretreatment and the resultant pulp is bleached in the form of a suspension with bleaching agent that increases the anionic charge of the pulp fibres, whereafter the pulp suspension is cleaned and then possibly further treated, for instance bleached, characterised in that the defibration is effected with the aid of a) a refiner that has counter-rotating refining discs while using an extra high temperature (HTDD), or b) a refiner that has a single rotating refining disc(s) having a single refining zone or two parallel refining zones, while using an extra high temperature and while rotating the disc(s) at an extra high speed (RTS), and in that the cleaning treatment comprises first screeming the pulp suspension and them hydrocyclone cleaning said suspension, wherewith the reject obtained with each cleaning process is treated individually and the treated reject is returned to the advancing pulp suspension.

  • 42.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Jonsson, Jonas
    Holmen Paper AB.
    Starck, Göran
    Holmen Paper aB.
    Wahlgren, Mikael
    Holmen Paper AB.
    Wancke-Ståhl, Charlotte
    Method of producing bleached thermomechanical pulp (tmp) or bleached chemithermomechanical pulp (ctmp) WO 2003000982 A12003Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    There is a need for a cheaper method of producing bleached TMP and CTMP without impairing the properties of the pulp. This is made possible by the present invention, which relates to a method of producing said pulps in which finely divided lignocellulosic material is defibrated after pretreatment and the resultant pulp is bleached in the form of a suspension with bleaching agent that increases the anionic charge of the pulp fibres, whereafter the pulp suspension is cleaned and then possibly further treated, for instance bleached, characterised in that the defibration is effected with the aid of a) a refiner that has counter-rotating refining discs while using an extra high temperature (HTDD), or b) a refiner that has a single rotating refining disc(s) having a single refining zone or two parallel refining zones, while using an extra high temperature and while rotating the disc(s) at an extra high speed (RTS), and in that the cleaning treatment comprises first screeming the pulp suspension and them hydrocyclone cleaning said suspension, wherewith the reject obtained with each cleaning process is treated individually and the treated reject is returned to the advancing pulp suspension.

  • 43.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Jonsson, Jonas
    Holmen Paper AB.
    Wancke-Ståhl, Charlotte
    Starck, Göran
    Holmen Paper aB.
    Wahlgren, Mikael
    Holmen Paper AB.
    Method of producing bleached thermomechanical pulp (tmp) or bleached chemithermomechanical pulp (ctmp)2004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    There is a need for a cheaper method of producing bleached TMP and CTMP without impairing the properties of the pulp. This is made possible by the present invention, which relates to a method of producing said pulps in which finely divided lignocellulosic material is defibrated after pretreatment and the resultant pulp is bleached in the form of a suspension with bleaching agent that increases the anionic charge of the pulp fibres, whereafter the pulp suspension is cleaned and then possibly further treated, for instance bleached, characterised in that the defibration is effected with the aid of a) a refiner that has counter-rotating refining discs while using an extra high temperature (HTDD), or b) a refiner that has a single rotating refining disc(s) having a single refining zone or two parallel refining zones, while using an extra high temperature and while rotating the disc(s) at an extra high speed (RTS), and in that the cleaning treatment comprises first screeming the pulp suspension and them hydrocyclone cleaning said suspension, wherewith the reject obtained with each cleaning process is treated individually and the treated reject is returned to the advancing pulp suspension.

  • 44.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Jonsson, Jonas
    Holmen Paper AB.
    Wancke-Ståhl, Charlotte
    Starck, Göran
    Holmen Paper aB.
    Wahlgren, Mikael
    Holmen Paper AB.
    Method of producing bleached thermomechanical pulp (tmp) or bleached chemithermomechanical pulp (ctmp) CA 2451155 A12003Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    There is a need for a cheaper method of producing bleached TMP and CTMP without impairing the properties of the pulp. This is made possible by the present invention, which relates to a method of producing said pulps in which finely divided lignocellulosic material is defibrated after pretreatment and the resultant pulp is bleached in the form of a suspension with bleaching agent that increases the anionic charge of the pulp fibres, whereafter the pulp suspension is cleaned and then possibly further treated, for instance bleached, characterised in that the defibration is effected with the aid of a) a refiner that has counter-rotating refining discs while using an extra high temperature (HTDD), or b) a refiner that has a single rotating refining disc(s) having a single refining zone or two parallel refining zones, while using an extra high temperature and while rotating the disc(s) at an extra high speed (RTS), and in that the cleaning treatment comprises first screeming the pulp suspension and them hydrocyclone cleaning said suspension, wherewith the reject obtained with each cleaning process is treated individually and the treated reject is returned to the advancing pulp suspension.

  • 45.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Nilsson, Carl, Fredrik
    FN Engineering AB.
    A method for selective removal of ray cells from cellulose pulp EP 1625253 A12006Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The content of ray cells in cellulose pulp causes problems and therefore these ray cells should be removed from the cellulose pulp to improve the pulp quality. The present invention makes this possible and comprises a method wherein at first an advancing pulp suspension is screened or vortex cleaned, (3) leading to the formation of an accept pulp fraction (4) and a reject pulp fraction (5) and that the reject pulp fraction is cleaned and divided, and that accepted material (pulp fibres and valuable fine material) is brought to further treatment and/or use. The invention is characterized in that the cleaning and division of the reject pulp suspension is carried out so that substantially all ray cells are present in the apex fraction of a fractionating cyclone (6) (if that is the kind of device used) and in that said fraction as such constitutes a very limited material stream, or in that a very limited material stream, predominantly containing ray cells is selected from the apex fraction, and in that this very limited material stream is brought to a disposal stage.

  • 46.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Nilsson, Carl, Fredrik
    FN Engineering AB.
    A method for selective removal of ray cells from cellulose pulp WO 2004097106 A12004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The content of ray cells in cellulose pulp causes problems and therefore these ray cells should be removed from the cellulose pulp to improve the pulp quality. The present invention makes this possible and comprises a method wherein at first an advancing pulp suspension is screened or vortex cleaned, (3) leading to the formation of an accept pulp fraction (4) and a reject pulp fraction (5) and that the reject pulp fraction is cleaned and divided, and that accepted material (pulp fibres and valuable fine material) is brought to further treatment and/or use. The invention is characterized in that the cleaning and division of the reject pulp suspension is carried out so that substantially all ray cells are present in the apex fraction of a fractionating cyclone (6) (if that is the kind of device used) and in that said fraction as such constitutes a very limited material stream, or in that a very limited material stream, predominantly containing ray cells is selected from the apex fraction, and in that this very limited material stream is brought to a disposal stage.

  • 47.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Nilsson, Carl, Fredrik
    FN Engineering AB.
    Method for selective removal of ray cells from cellulose pulp US 20070023329 A12007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The content of ray cells in cellulose pulp causes problems and therefore these ray cells should be removed from the cellulose pulp to improve the pulp quality. The present invention makes this possible and comprises a method wherein at first an advancing pulp suspension is screened or vortex cleaned, (3) leading to the formation of an accept pulp fraction (4) and a reject pulp fraction (5) and that the reject pulp fraction is cleaned and divided, and that accepted material (pulp fibres and valuable fine material) is brought to further treatment and/or use. The invention is characterized in that the cleaning and division of the reject pulp suspension is carried out so that substantially all ray cells are present in the apex fraction of a fractionating cyclone (6) (if that is the kind of device used) and in that said fraction as such constitutes a very limited material stream, or in that a very limited material stream, predominantly containing ray cells is selected from the apex fraction, and in that this very limited material stream is brought to a disposal stage.

  • 48.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sandberg, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wancke-Ståhl, Charlotte
    Jonsson, Jonas
    Holmen Paper AB.
    Starck, Göran
    Holmen Paper aB.
    Wahlgren, Mikael
    Holmen Paper AB.
    Method of producing bleached thermomechanical pulp (tmp) or bleached chemithermomechanical pulp (ctmp) US 20040231811 A12004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    There is a need for a cheaper method of producing bleached TMP and CTMP without impairing the properties of the pulp. This is made possible by the present invention, which relates to a method of producing said pulps in which finely divided lignocellulosic material is defibrated after pretreatment and the resultant pulp is bleached in the form of a suspension with bleaching agent that increases the anionic charge of the pulp fibres, whereafter the pulp suspension is cleaned and then possibly further treated, for instance bleached, characterised in that the defibration is effected with the aid of a) a refiner that has counter-rotating refining discs while using an extra high temperature (HTDD), or b) a refiner that has a single rotating refining disc(s) having a single refining zone or two parallel refining zones, while using an extra high temperature and while rotating the disc(s) at an extra high speed (RTS), and in that the cleaning treatment comprises first screening the pulp suspension and then hydrocyclone cleaning said suspension, wherewith the reject obtained with each cleaning process is treated individually and the treated reject is returned to the advancing pulp suspension.

  • 49. Eriksson, Malin
    et al.
    Pettersson, Gunilla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wågberg, Lars
    Application of polymeric multilayers of starch onto wood fibres to enhance strength properties of paper2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, no 3, 270-275 p.Article in journal (Refereed)
    Abstract [en]

    Polyelectrolyte multilayers of cationic and anionic starch have been used to enhance the strength properties of paper. All starches used in this investigation had a degree of substitution around 0.065. Optical reflectometry showed that a combination of cationic and anionic starch could form polyelectrolyte multilayers onto silicon oxide surfaces. The same combination of starches was then applied to unbeaten, bleached softwood kraft fibres to form three layers, i.e. a cationic/anionic/cationic starch combination. The results showed a significant increase in the paper strength properties in terms of tensile index, strain at break, and Scott Bond. The adsorbed amount of starch in the sheets, determined using an enzymatic method, was found to increase with each successive starch treatment. The increased paper strength was not only due to the increase in adsorbed amount of starch; rather, the chemical composition of the starch was also important. Cationic starch with high amylose content had a more positive effect on the paper strength properties. Furthermore, it was observed that anionic starch, despite being adsorbed in large amounts, did not contribute to the increase in tensile strength or strain at break to the same extent as did cationic starch. However, the out-of-plane properties, measured as Scott Bond properties, increased with the adsorbed amount, regardless of the chemical composition of the starch used in the outermost layer.

  • 50.
    Forsström, Jennie
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Eriksson, Malin
    Wågberg, Lars
    A new technique for evaluating ink–cellulose interactions: initial studies of the influence of surface energy and surface roughness2005In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 19, no 9, 783-798 p.Article in journal (Refereed)
    Abstract [en]

    Ink–cellulose interactions were evaluated using a new technique in which the adhesion properties between ink and cellulose were directly measured using a Micro-Adhesion Measurement Apparatus (MAMA). The adhesion properties determined with MAMA were used to estimate the total energy release upon separating ink from cellulose in water. The total energy release was calculated from interfacial energies determined via contact angle measurements and the Lifshitz–van der Waals/acid–base approach. Both methods indicated spontaneous ink release from model cellulose surfaces, although the absolute values differed because of differences in measuring techniques and different ways of evaluation. MAMA measured the dry adhesion between ink and cellulose, whereas the interfacial energies were determined for wet surfaces. The total energy release was linked to ink detachment from model cellulose surfaces, determined using the impinging jet cell. The influences of surface energy and surface roughness were also investigated. Increasing the surface roughness or decreasing the surface energy decreased the ink detachment due to differences in the molecular contact area and differences in the adhesiom properties.

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