Chemistry and Technology of Printing and Imaging Systems

Transcription

1 Chemistry and Technology of Printing and Imaging Systems

2 Chemistry and Technology of Printing and Imaging Systems Edited by P. GREGORY Zeneca Specialties Manchester SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

3 First edition Springer Science+Business Media Dordrecht OriginalIy published by Chapman & HalI in 1996 Softcover reprint ofthe hardcover lst edition 1996 Typeset in 10/12pt Times by Cambrian Typesetters, Frim1ey, Surrey ISBN ISBN (ebook) DOI / Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the Glasgow address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A cata10gue record for this book is available from the British Library Library of Congress Catalog Card Number: ~ Printed on permanent acid-free text paper, manufactured in accordance with ANSIINISO Z (Permanence of Paper).

4 Preface Printing and imaging has a major impact on everyone. From the obvious examples of newspapers, magazines and comics through to photographs, currency and credit cards, and even the less obvious example of compact discs, everyone is familiar with the end products of printing and imaging. Until recently, the major printing and imaging technologies have been impact printing and silver halide photography. Important impact printing technologies are offset lithography, gravure, flexography and screen printing. All these technologies, including silver halide photography, are mature and have changed little over the past few decades. In contrast, the phenomenal growth of silicon chip technology over the past 15 years or so has spawned a new era of printing and imaging systems, the so-called nonimpact (or electronic) printers. Not all the non-impact printing technologies are of equal commercial importance. Some, like diazotype and conventional photolithography, are mature and are declining in importance. Other technologies, though relatively new, have not achieved notable commercial success. Electrography and magnetography fall into this category. The remaining technologies such as optical data storage (the technology used in compact discs), thermography (the technology used in electronic photography), inkjet printing and electrophotography are the non-impact printing technologies that are both modern and which have achieved remarkable commercial success, especially ink-jet printing and electrophotography. Indeed, electrophotography, the technology which embraces photocopiers and laser printers, together with the more recent ink-jet printers, are now the standard office printers, having displaced the once dominant impact printers such as typewriters, daisywheel and dot-matrix. This revolution has seen printing move from the workshop and darkroom into the office and home. The advances in non-impact printing technologies are now beginning to be incorporated into some of the mature technologies to improve their performance. Examples include the use of photoconductor technology used in electrophotography, and laser imaging used in optical data storage, to produce lithographic plates, both technologies having advantages over the established photolithography. Indeed, as time progresses there will be more of this interaction of modern technologies with mature technologies. Because of the rapid changes in the printing and imaging technologies over the last decade, the time is ripe for a book. I am honoured to have

5 VI PREFACE been asked to edit such a book and wish to thank all the contributors for their excellent contributions. Finally I would like to thank my wife, Vera, and two sons, Andrew and Michael, for their perseverance and patience during this project, and Dr Alan Calder, General Manager of Zeneca Specialties, for use of the library and secretarial facilities, especially Amanda Collier for typing several chapters. Peter Gregory

6 Contributors P. Bergthaller Agfa Gevaert AG, Postfach , D Leverkusen, Germany R. Bradbury Zeneca Specialties, PO Box 42, Hexagon House, Blackley, Manchester M9 8ZS, UK R.S. Gairns Zeneca Specialties, PO Box 42, Hexagon House, Blackley, Manchester M9 8ZS, UK P. Gregory Zeneca Specialties, PO Box 42, Hexagon House, Blackley, Manchester M9 8ZS, UK P.A. Hunt T.S. Jewitt ICI Imagedata, Brantham, Manningtree, Essex COl1 INL, UK Department of Communication Media, Manchester Metropolitan University, Cavendish Street, Manchester M15 3BR, UK R. W. Kenyon Zeneca Specialties, PO Box 42, Hexagon House, Blackley, Manchester M9 8ZS, UK

7 Contents 1 Setting the scene 1 P. GREGORY 1.1 From maturity to mayhem The ubiquitous silicon chip The environment Themes and focii 3 References 3 2 Traditional impact printing 4 T.S. JEWITT 2.1 Introduction A brief history of printing Printing technologies Relief printing Letterpress Flexography Intaglio printing Planographic printing The offset printing press Image quality The image on the plate The offset blanket Fount solution Lithographic inks Cold-set web-offset inks Heat-set web-offset inks Sheet-fed lithographic inks The printing industry Applications of the printing processes Letterpress Flexography Gravure Screen printing Lithography Web offset Commercial aspects of the British printing industry Electronic imaging Scanning Output Proofing Digital platemaking Digital printing Printing and the environment 33 References and further reading 34

8 X CONTENTS 3 Silver halide photography 35 P. BERGTHALLER 3.1 History and evolution of photographic imaging systems Photography in black-and-white Concepts of photography in colour: the steps of the pioneers Silver halide photography today: the market The physical basis of silver halide photography A brief look at the elementary processes in the silver halide crystal The photographic emulsion Photographic development Detail rendition Development and colour: subtractive colour photography vs. additive colour photography Photographic materials Film Printing media The chemical constituents of photographic media Emulsion ingredients and additives Developers and processing chemistry Colour couplers and special-purpose couplers The chemistry of the silver-dye-bleach process The chemistry of dye diffusion systems Photographic quality Future of photographic media Frontiers of the technically feasible Remote sensing and recording Digital storage of photographic images: a powerful tool for information management and archiving The merging of technologies: hybrid media and digital imaging The merging of uses (communication and entertainment) Ecological challenges of photographic processing The advanced photo system 74 References 74 4 Electrophotography 76 R.S. GAIRNS 4.1 Introduction The technology ofxerography Charging Exposure Image enhancement Development Fixing and cleaning Consumables Photoconductors Charge-generation materials (CGMs) Charge-transport materials (CTMs) Developer Advantages of electrophotography Limitations of electrophotography Competition 104

9 CONTENTS xi 4.7 Synergy Photoactive pigment electrophoresis (P APE) Electrography and ionography Lithography TonerJet Uses of electrophotography Toxicology and the environment Future 110 References Inkjet printing 113 R.W. KENYON 5.1 Introduction Ink jet technology Continuous ink jet Drop-on-demand ink jet Ink jet inks General features Aqueous inks Solvent inks Hot-melt inks Ink jet colorants Black dyes (first generation) Colour dyes (first generation) Second-generation colorants Phase-change colorants Colorants for industrial ink jet printers Ink jet ink/colorant research Advantages/limitations of ink jet Uses of ink jet printers Office segment Industrial segment Colour filters for LCDs (Liquid crystal displays) Ink jet printing oftextiles Toxicology and the environment Futureofinkjet 137 References Thermal printing 139 R. BRADBURY 6.1 Introduction Direct thermal printing Colour formers Developers Sensitisers Multicolour thermal paper Direct thermal markets Mead Cycolor process Photoinitiators Dye-diffusion thermal transfer (D2T2) Dye sheet ( dye donor sheet) Receiver sheet Dye-diffusion thermal-transfer dyes D2T2market 162

10 XII CONTENTS 6.5 Thermal-melt transfer Dyesheet Melt-transfer colorants Receiver sheets Printing Thermal melt-transfer market References Optical data-storage systems P.A. HUNT 7.1 Introduction 7.2 Principles of operational functionality Read-only memory (ROM) Erasable versus write-once Physical and chemical requirements 7.3 System options Metallic ablative (WORM) Metallic phase-change (WO RM and erasable) Dye-polymer ablative (WORM) Photochromic dye (erasable) Liquid crystals (WORM and erasable) Metallic interference (WORM) 7.4 Technical performance features of ODS systems Performance advantages of ODS systems Performance limitations in ODS systems 7.5 Commercial performance features 7.6 Comparison with alternative technologies Magnetic media Magneto-optical (MO) media 7.7 Related technologies 7.8 Applications of ODS 7.9 Toxicology and environmental considerations 7.10 The future References Electrostatic, ionographic, magnetographic and embryonic printing technologies 195 P. GREGORY 8.1 Introduction 8.2 Electrographic printing 8.3 Ionographicprinting 8.4 Magnetographic printing 8.5 Embryonic printing technologies High-resolution dry-processing film (VerdeFilm) Toner fusion xeroprinting TonerJet 8.6 Future prospects References

11 CONTENTS xiii 9 Thefuture P. GREGORY Index 9.1 Introduction 9.2 Short-term predictions Traditional printing and imaging Non-impact printing and imaging 9.3 Longer-term predictions Evolutionary developments Revolutionary developments 9.4 Conclusion References