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  • 1.
    Boudreau, Jonna
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    A close-up on Yankee coating - for better control2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 2.
    Boudreau, Jonna
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Improvement of the tissue manufacturing process2009Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The creping process and the conditions on the Yankee cylinder are the key factors in the production process. They need to be kept under good control in order to maintain a high and uniform quality. A natural coating always develops on the surface of the Yankee cylinder due to evaporation from dissolved and dispersed substances and to fiber fragments that remain on the surface after creping. Nevertheless, coating chemicals are sprayed onto the Yankee surface in order to modify the adhesion between the paper and the dryer cylinder. To be able to control the process, on-line measurements of coating thickness as well as of the crepe structure of the tissue paper produced would be very valuable. In the work described in this thesis, the coating layer was analyzed chemically and morphologically to provide information about the coating layer before starting any on-line measurements. The chemicals added and the constituents of the pulps are known to the paper producers, but what is left on the cylinder and whether there are different layers of coating still remain to be investigated. The chemical analysis indicated that the adhesive content was higher in an inner layer of the coating than in the outer layer. The relative amount of polyamide-amine resin calculated on the basis of the nominal nitrogen content in the resin was low indicating that the coating consisted of a significant amount of carbohydrates or other substances. The coating layer could not be considered transparent. It was observed that the coating was thick and appeared patch-wise and that it contained fiber fragments. Measurements on a laboratory scale, to further be applied on-line on the tissue machine, have been investigated and evaluated in this study. The thickness of the coating layer on a laboratory dryer has been measured. The method was based on fluorescence with an optical brightener added to the coating chemicals sprayed on the Yankee dryer. With a UV-LED (Ultra Violet - Light Emitting Diode) the coating layer was exposed to UV-light and the intensity of the light emitted by the optical brightener in the layer was measured. The intensity in the trials with different thickness of the coating and no coating was scattered and no trend could be seen between the different trial points. Attempts were made to measure the wavelength of the tissue paper produced with an optical fiber perpendicular to and at an angle to the paper surface. The paper was travelling in a slow speed while the measurements were made. The collected signal to noise ratio was low and it was not possible to detect any representative characteristic wavelength of the tissue.

  • 3.
    Boudreau, Jonna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    New methods for evaluation of tissue creping and the importance of coating, paper and adhesion2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The creping process and the conditions on the Yankee cylinder dryer are key factors in a tissue paper mill, and they therefore need to be kept under good control in order to maintain a high and uniform quality. To this end it would be valuable to be able to make on-line measurements of Yankee coating thickness as well as the crepe structure of the tissue paper. The adhesion of paper to the cylinder affects the creping process and more information about the parameters that affect the adhesion is therefore of interest. To perform trials on a full scale or in a pilot plant is very costly and laboratory creping equipment is therefore sought after in order to be able to measure the adhesion force.

    The coating layer for use on the cylinder was analysed. It contained a large amount of carbohydrates and could not be considered transparent. The thickness of the coating layer was measured on a laboratory cylinder with a method based on fluorescence. An optical brightener was added to the coating chemicals and the coating layer was subjected to UV-radiation. The intensity of the light emitted by the optical brightener was measured and gave an indication of the thickness of the coating layer. The equipment has to be further investigated before it is possible to implement the new sensor on-line.

    New creping equipment and an adhesion method were developed for use on a laboratory scale. The equipment can operate with different creping angles and the force needed to crepe the paper can be measured. The highest creping force was obtained for papers of high grammage, low dryness at adhesion, high drainability, high fines content and high hemicellulose content.

    A more direct method is to analyse the structure of the produced paper. Measurements were made on a tissue paper with an optical fibre sensor while the paper was travelling at low speed. The collected signal was mathematically analysed and the characteristic wavelength was calculated for different paper samples. These values were close to the wavelengths measured with an off line method by a commercial crepe analyser.

  • 4.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Barbier, Christophe
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Laboratory creping equipment2014Inngår i: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 28, nr 6, s. 561-572Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tissue production is largely dependent on the creping process as creping influences the paper properties and thus the quality of the end product and the runnability of the tissue machine. The process is very complex and includes numerous variables affecting the adhesion, and ultimately the creping of the tissue paper. To perform experiments on a full scale machine, or even a pilot machine, is very costly, therefore a laboratory scale creping device is demanded, able to replicate conditions encountered on a tissue machine. In this paper new laboratory testing equipment is developed, whereby the adhesion between paper and metal surfaces (when scraping off the paper with configurations similar to the industrial process) can be studied. A new method to adhere paper to metal, used in the new laboratory creping equipment, is also developed. To evaluate the equipment, different creping angles were tested. The scraping tests show a trend in decreasing creping force for an increasing creping angle.

  • 5.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Beghello, Luciano
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    A Method of Measuring the Thickness of the Coating on a Dryer Cylinder2009Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, nr 3, s. 309-312Artikkel i tidsskrift (Fagfellevurdert)
  • 6.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Beghello, Luciano
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Experiments to Find Online Measurements of the Structure of the Tissue Paper SurfaceManuskript (Annet (populærvitenskap, debatt, mm))
  • 7.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Influence of Various Pulp Properties on the Adhesion Between Tissue Paper and Yankee Cylinder Surface2014Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, nr 2, s. 2107-2114Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The strength of the adhesion between the paper and the drying Yankee cylinder is of great importance with respect to the final properties of a tissue paper product. Therefore, the effects of a few potentially important pulp properties have been evaluated in laboratory experiments. Four highly different kraft pulps were used, and the adhesion strength was measured by means of the force required when scraping off a paper from a metal surface with a specifically designed knife mounted on a moving cart. The adhesion strength was observed to increase with increasing grammage and increasing degree of beating of the pulp. It was also found that pulpscontainingmore fines, or with higher hemicellulose content, gave rise to higher adhesion strength.

  • 8.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Hollmark, Holger
    Hollmark Imptec AB.
    Beghello, Luciano
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Chemical and Morphological Analyses of the Tissue Yankee Coating2009Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, nr 1, s. 52-59Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Hollmark, Holger
    Beghello, Luciano
    Method for analyzing cylinder coating on tissue machines2008Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Samples of coating have been taken at different positions on a running Yankee cylinder

    to analyze the content. The scrapings of the coating were obtained by collecting material

    from the cleaning doctor and by scraping coating with a hand scraper in between the

    cleaning doctor and the spray boom. The conditions on the Yankee dryer surface were

    varied by varying specific creping additives. Chemical and morphological analyses were

    made on the samples. The chemical analysis comprised carbohydrate analysis and

    nitrogen analysis. Analyses of the scrapings were compared with analyses of the creped

    paper. Replicas of the coating layer were made with a silicon rubber to show the

    microstructure. The coating was thick and appeared patch-wise and it contained fiber

    fragments. The chemical analysis indicates that the nitrogen content was higher for the

    coating close to the cylinder. The sampling method seems to work well, since the

    nitrogen content increases with an increased amount of applied adhesive

  • 10.
    Boudreau, Jonna
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Mossberg, Magnus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Barbier, Christophe
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Experiments to Find On-line Measurements of the Structure of the Tissue Paper SurfaceArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure of tissue paper has great influence on the quality of the resulting paper produced. One method of measuring the crepe wavelength on-line is sought in order to improve process control as well as to promote greater precision and uniform quality of the end product. In this study, a probe was used to read the surface of the paper whilst the paper travelled at a low speed. Light from a light emitting diode was emitted at a specific angle and collected at the corresponding reflecting angle, from the paper surface.

     

    Focusing the lenses at 45º angle produced results matching closest to the expected wavelength, and such measurements were made on a numerous commercial papers to validate the method. The collected signal contains a lot of information from the surface of the paper and from reflected signals inside the paper. The signal was processed using a mathematical approach to extract the most common wavelengths for each paper. The measured wavelength was found to closely match measurements made with commercial off-line equipment. This new method has a good initial potential to work on-line, however further investigation regarding the effects of high speeds upon the sampling still has to be carried out. 

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