Papermaking Chemistry

Transcription

1 Papermaking Science and Technology a book series covering the latest technology and future trends Book 4 Papermaking Chemistry Second Edition Totally updated version Book editor Raimo Alén, Dr.Tech., Professor, University of Jyväskylä, Laboratory of Applied Chemistry, Jyväskylä, Finland Publisher Finnish Paper Engineers Association/Paperi ja Puu Oy Paperi ja Puu Oy

2 Table of Contents 1 Introduction to papermaking General aspects of papermaking chemistry Papermaking additives Internal sizing of paper Deposit formation and control Paper machine microbiology Overview of analytical methods in wet-end chemistry Appendix Conversion factors Index

3 CHAPTER 1 Introduction to papermaking 1 Historical milestones General aspects on pulps Common paper grades Importance of papermaking chemistry...22 References...25 For further reading

4 Chapter 2 General aspects of papermaking chemistry 1 Introduction Surface properties of pulps Surface structure of fibres and fines Surface chemical composition of pulps Surface charge of pulps Surface properties of fillers General properties of papermaking additives Polymers Fixing agents Retention chemicals Dry- and wet-strength resins Sizing dispersions and emulsions Rosin sizing Neutral sizing Factors influencing the adsorption of additives Polymer properties Pulp properties Water phase properties Colloidal interactions between papermaking materials Hydrodynamic and kinetic effects...49 References

5 CHAPTER 3 Papermaking additives 1 Introduction Mineral fillers and pigments Paper fillers Coating and specialty pigments Effects of fillers Techniques for use of minerals Filler retention Current and emerging pigment technology Need for more strength in filled papers Papermaking chemicals Functional chemicals Dry-strength chemicals Starch Other natural strength additives Synthetic dry-strength additives Wet-strength chemicals Initial wet web strength Re-wetted web strength Wet-strength mechanisms Wet-strength resins Repulpability New approaches to acquire wet strength and runnability Uses of wet-strengthened paper Remarks on wet strength Sizes Dyes and optical brighteners

6 Papermaking additives 4.5 Coating colour additives Other functional chemicals Process chemicals Fixatives Adsorbents Retention and drainage polymers Polymer types Flocculation mechanisms Defoaming agents Biocides and detergent-related agents Other process chemicals Dosing of chemicals Process control of wet-end additives Economic aspects of additives Future perspectives Nanotechnology Self-assembly of monomolecular layers REACH References

7 Chapter 4 Internal sizing of paper 1 Introduction Historical background Basic mechanisms involved in sizing Fibre and paper surfaces Wetting and spreading Contact angle, wetting, and adhesion Spreading Adsorption Rough and heterogeneous surfaces Contact angle hysteresis Quantification of roughness and heterogeneity Kinetics of wetting Capillary penetration Extent and mechanisms of sizing Tests of sizing Analysis of paper surfaces and sizing mechanisms Rosin sizing Origin and synthesis of rosin sizes Rosin sizing in acid papermaking Aluminium chemistry Sizing with saponified rosin Sizing using dispersed rosin Rosin sizing in neutral papermaking Sizing with alkenyl succinic anhydride (ASA) Synthesis of ASA Preparation of ASA emulsions

8 Internal sizing of paper 6.3 Reactions of ASA sizing Spreading and wetting of ASA on paper surfaces Sizing with alkyl ketene dimer (AKD) Preparation of AKD dispersions Reactions, spreading, and wetting of AKD on paper surfaces Size reversion Comparison of sizes References

9 Chapter 5 Deposit formation and control 1 Introduction Deposits Sources Principles of formation Effects on process performance Process control General aspects Deposit-control agents Practical examples Conclusions References

10 Chapter 6 Paper machine microbiology 1 Introduction Microorganisms the enemies Taxonomy of microorganisms Bacteria Functional classification of bacteria Aerobic bacteria Anaerobic bacteria Sulphate-reducing bacteria (SRB) Fungi Other microorganisms Growth of microorganisms in paper mills General aspects Paper machine as an ecosystem Problems caused by microbes Microbiological deposits (slimes and biofilms) Prevention of biofilm formation Other runnability problems Spoilage of raw materials Problems caused by anaerobic microbes Heat-resistant spores Microbially influenced corrosion (MIC) How to avoid microbiological problems Application of biocides (microbicides) Different types of biocide Other methods Good housekeeping Microbiological analytics References

11 Chapter 7 Overview of analytical methods in wet-end chemistry 1 Introduction General aspects on substances in the wet end Description of analytical methods Chemical characterisation of papermaking process waters Wood-derived compounds General approach Carbohydrates Extractives Lignin Miscellaneous organics and inorganics Papermaking additives Sizing agents Other compounds On-line process methods Conclusions and future perspectives References