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Experiments to Find On-line Measurements of the Structure of the Tissue Paper Surface
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.ORCID iD: 0000-0001-9545-7836
(English)Article in journal (Refereed) Submitted
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. 

Keyword [en]
tissue paper, creping, wavelength, non-destructive, measurement surface, signal processing
National Category
Engineering and Technology
Research subject
Physics; Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-29925OAI: oai:DiVA.org:kau-29925DiVA: diva2:660322
Available from: 2013-10-29 Created: 2013-10-29 Last updated: 2014-10-28Bibliographically approved
In thesis
1. New methods for evaluation of tissue creping and the importance of coating, paper and adhesion
Open this publication in new window or tab >>New methods for evaluation of tissue creping and the importance of coating, paper and adhesion
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Abstract [en]

Baksidestext

The creping process is the heart of tissue paper manufacture. To control the process better, on-line measurements of paper structure and coating thickness are sought after. The creping is highly dependent on the adhesion of the paper to the Yankee dryer. To be able to measure the adhesion, laboratory creping equipment was also required. Different pulp parameters affect the adhesion and some of them have been investigated in this work.

The coating on the Yankee cylinder consisted mainly of fiber fragments and could not be considered as transparent, which had to be considered when choosing a method to measure coating thickness. A method based on the light emitted from an optical brightener in the coating when subjected to UV-irradiation was used, but has to be further improved before it can be used on-line.

A new laboratory creping method was developed to determine the adhesion between paper and metal, and the force needed to scrape off the paper with a doctor blade was measured. The highest creping force was obtained for papers made of pulp with a high drainability, high fines content and high hemicellulose content.

An optical method using reflected light to measure crepe wavelength on-line was developed. The paper travelled under a sensor and the light collected was mathematically analyzed to determine the most common wavelength.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2013. 60 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2013:47Karlstad University Studies, ISSN 1403-8099
Keyword
tissue, creping, paper adhesion, Tissue paper, creping, paper adhesion, coating layer, adhesives, Yankee cylinder, crepe structure, wavelength measurements
National Category
Engineering and Technology
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-29317 (URN)978-91-7063-525-0 (ISBN)
Public defence
2013-12-13, Nyqvistsalen, Karlstads universitet, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2013-11-22 Created: 2013-10-07 Last updated: 2015-11-26Bibliographically approved

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