Barrier properties of greaseproof 5289/ آ  Barrier properties of greaseproof paper Barrier

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  • Division for Chemistry Department of Chemical Engineering

    Karlstad University Studies 2005:17

    Henrik Kjellgren

    Barrier properties of greaseproof paper

    Barrier properties of greaseproof paper

    The barrier properties of greaseproof paper are achieved by extensive beating of the fibres. This treatment results in high costs for energy, both as beating energy and drying energy. A full-scale trial has been performed to investigate the role of the pulp with respect to energy demand and the barrier properties of the final papers. The paper made of 100% sulphite pulp with a low degree of beating showed the lowest energy consumption at a given level of barrier properties such as air permeance, grease resistance and water vapour transmission rate.

    The papers produced in the full-scale trial have been used as substrates for coating. Greaseproof paper has a closed surface and should therefore be a good base paper for barrier coatings.

    Chitosan has been used as a barrier coating because of its good oxygen barrier properties. Moreover, chitosan is a renewable material. Coating trials on a bench-scale showed that greaseproof paper can be upgraded to provide a good oxygen barrier. The oxygen barrier could not be achieved on a pilot-scale using the metered size press technique, because of the low coat weight applied.

    The influence of the base paper on the barrier properties of chitosan-coated paper has been investigated. It was found that greaseproof paper is better than a paper with a higher porosity. The coating seemed to stay more on the surface of the greaseproof papers and to form a continuous coating layer with better barrier properties.

    Karlstad University Studies ISSN 1403-8099

    ISBN 91-85335-57-6

    H enrik K

    jellgren B arrier properties of greaseproof paper

  • Karlstad University Studies

    2005:17

    Henrik Kjellgren

    Barrier properties of greaseproof paper

  • Henrik Kjellgren. Barrier properties of greaseproof paper.

    Licenciate Thesis

    Karlstad University Studies 2005:17 ISSN 1403-8099 ISBN 91-85335-57-6

    © The author

    Distribution: Karlstad University Division for Chemistry Department of Chemical Engineering SE-651 88 KARLSTAD SWEDEN +46 54-700 10 00

    www.kau.se

    Printed at: Universitetstryckeriet, Karlstad 2005

  • Henrik Kjellgren

    Barrier properties of greaseproof paper

  • Varför forskar ni om papper? Papper är ju redan uppfunnet! - Bo Jonsson

  • i

    Abstract The barrier properties of greaseproof paper are achieved by extensive beating of the fibres. This treatment results in high costs for energy, both as beating energy and drying energy. A full-scale trial has been performed to investigate the role of the pulp with respect to energy demand and the barrier properties of the final papers. The paper made of 100% sulphite pulp with a low degree of beating showed the lowest energy consumption at a given level of barrier properties such as air permeance, grease resistance and water vapour transmission rate. The papers produced in the full-scale trial have been used as substrates for coating. Greaseproof paper has a closed surface and should therefore be a good base paper for barrier coatings. Chitosan has been used as a barrier coating because of its good oxygen barrier properties. Moreover, chitosan is a renewable material. Coating trials on a bench-scale showed that greaseproof paper can be upgraded to provide a good oxygen barrier. The oxygen barrier could not be achieved on a pilot-scale using the metered size press technique, because of the low coat weight applied. The influence of the base paper on the barrier properties of chitosan-coated paper has been investigated. It was found that greaseproof paper is better than a paper with a higher porosity. The coating seemed to stay more on the surface of the greaseproof papers and to form a continuous coating layer with better barrier properties.

  • ii

    List of Papers The following papers are included in this thesis and are referred to by their Roman numerals in the text: I Kjellgren, H. and Engström, G. (2004):

    The relationship between energy requirement and barrier properties in the production of greaseproof paper.

    Submitted to Tappi Journal. II Kjellgren, H., Gällstedt, M., Engström, G. and Järnström, L. (2004): Barrier and surface properties of chitosan-coated greaseproof paper. Submitted to Carbohydrate Polymers. III Kjellgren, H. and Engström, G. (2005):

    Influence of base paper on the barrier properties of chitosan-coated papers. Manuscript in preparation.

  • Table of contents Introduction......................................................................................................................... 2 Barrier Properties ................................................................................................................ 5

    Porosity ........................................................................................................................... 5 Air permeance ................................................................................................................. 6 Grease resistance............................................................................................................. 8 Water absorbency............................................................................................................ 9 Barrier to gases ............................................................................................................. 11 Water vapour transmission ........................................................................................... 11 Oxygen permeability..................................................................................................... 13

    Material Properties............................................................................................................ 15 Fibre structure ............................................................................................................... 15 Swelling ........................................................................................................................ 16 Chitosan ........................................................................................................................ 17

    Production of Greaseproof Paper...................................................................................... 20 Beating .......................................................................................................................... 20 Paper machine ............................................................................................................... 21 Coating.......................................................................................................................... 22 Calendering ................................................................................................................... 23

    Experimental and Methods used in the Papers ................................................................. 24 Production of greaseproof paper ................................................................................... 24 Bench-scale coating ...................................................................................................... 24 Pilot-scale coating......................................................................................................... 25 Calendering ................................................................................................................... 25 Test methods ................................................................................................................. 25

    Summary of the papers ..................................................................................................... 29 Paper I: .......................................................................................................................... 29 Paper II:......................................................................................................................... 31 Paper III:. ...................................................................................................................... 33

    Conclusions....................................................................................................................... 35 Acknowledgments............................................................................................................. 36 References......................................................................................................................... 37

  • INTRODUCTION

    2

    Introduction

    Greaseproof paper was first developed as a replacement for parchment by the engineer Otto Munthe Tobiesen in 1894 at the Granfoss mill in Norway (Mathiesen and Danielsen, 1994). The cooking was performed at a low temperature and with high amount of calcium in the white liquor. This resulted in a sulphite pulp which after a long beating time gave a grease-resistant paper. The special properties of greaseproof paper are mainly due to the high degree of beating which creates many bonding sites on each fibre, which in turn create a paper of high density. Greaseproof paper has a closed surface structure with a small number of large surface pores (Stolpe, 1986). This suggests that greaseproof paper with its closed surface structure can be an