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Chemistry and Technology of and Imaging Systems

Edited by

P. GREGORY Zeneca Specialties Manchester

BLACKIE ACADEMIC & PROFESSIONAL An Imprint of Chapman & Hall London • Glasgow • Weinheim • New York • Tokyo • Melbourne • Madras •vi.

Contents

1 Setting the scene P. GREGORY

1.1 From maturity to mayhem 1 1.2 The ubiquitous silicon chip 1 1.3 The environment 2 1.4 Themes and focii 3 References 3

Traditional impact printing 4 T.S. JEWITT

2.1 Introduction 4 2.2 A brief 4 2.3 Printing technologies 7 2.3.1 7 2.3.2 Letterpress 7 2.3.3 9 2.3.4 printing 11 2.3.5 Pianographic printing 13 2.4 The offset 16 2.4.1 Image quality 16 2.4.2 The image on the plate 16 2.4.3 The offset blanket 17 2.4.4 Fount solution 17 2.5 Lithographic inks 18 2.5.1 Cold-set web-offset inks 18 2.5.2 Heat-set web-offset inks 19 2.5.3 Sheet-fed lithographic inks 19 2.6 The printing industry 21 2.7 Applications of the printing processes 22 2.7.1 Letterpress 22 2.7.2 Flexography 22 2.7.3 Gravüre 22 2.7.4 Screenprinting 23 2.7.5 24 2.7.6 Web offset 24 2.8 Commercial aspects of the British printing industry 25 2.9 Electronic imaging 26 2.9.1 Scanning 27 2.9.2 Output 28 2.9.3 Proofing 28 2.9.4 Digital platemaking 29 2.9.5 31 2.10 Printing and the environment 33 References and further reading 34 CONTENTS

Silver halide photography P. BERGTHALLER

3.1 History and evolution of photographic imaging systems 3.1.1 Photography in black-and-white 3.1.2 Concepts of photography in colour: the steps of the pioneers 3.1.3 Silver halide photography today: the market 3.2 The physical basis of silver halide photography 3.2.1 A brief look at the elementary processes in the silver halide crystal 3.2.2 The photographic emulsion 3.2.3 Photographic development 3.2.4 Detail rendition 3.2.5 Development and colour: subtractive colour photography additive colour photography 3.3 Photographic materials 3.3.1 Film 3.3.2 Printing media 3.4 The chemical constituents of photographic media 3.4.1 Emulsion ingredients and additives 3.4.2 Developers and processing chemistry 3.4.3 Colour couplers and special-purpose couplers 3.4.4 The chemistry of the silver-dye-bleach process 3.4.5 The chemistry of dye diffusion systems 3.5 Photographic quality 3.6 Future of photographic media 3.6.1 Frontiers of the technically feasible 3.6.2 Remote sensing and recording 3.6.3 Digital storage of photographic images: a powerful tool for information management and archiving 3.6.4 The merging of technologies: hybrid media and digital imaging 3.6.5 The merging of uses (communication and entertainment) 3.6.6 Ecological challenges of photographic processing 3.6.7 The advanced photo system References

Electrophotography R.S. GAIRNS

4.1 Introduction 4.2 The technology of 4.2.1 Charging 4.2.2 Exposure 4.2.3 Image enhancement 4.2.4 Development 4.2.5 Fixing and cleaning 4.3 Consumables 4.3.1 Photoconductors 4.3.2 Charge-generation materials (CGMs) 4.3.3 Charge-transport materials (CTMs) 4.3.4 Developer 4.4 Advantages of electrophotography 4.5 Limitations of electrophotography 4.6 Competition •г

CONTENTS XI

4.7 Synergy 105 4.7.1 Photoactive pigment electrophoresis (PAPE) 105 4.7.2 Electrography and ionography 106 4.7.3 Lithography 106 4.7.4 TonerJet ' 108 4.8 Uses of electrophotography 108 4.9 Toxicology and the environment 109 4.10 Future 110 References 110

5 113 R.W. KENYON

5.1 Introduction 113 5.2 Ink jet technology 114 5.2.1 Continuous ink jet 114 5.2.2 Drop-on-demand ink jet 115 5.3 Inkjetinks 119 5.3.1 General features 119 5.3.2 Aqueous inks 119 5.3.3 Solvent inks 120 5.3.4 Hot-melt inks 121 5.4 Ink jet colorants 121 5.4.1 Black dyes (first generation) 121 5.4.2 Colour dyes (first generation) 123 5.5 Second-generation colorants 126 5.6 Phase-change colorants 129 5.7 Colorants for industrial ink jet printers 130 5.8 Ink jet ink/colorant research 130 5.9 Advantages/limitations of ink jet 131 5.10 Uses of ink jet printers 132 5.10.1 Office segment 132 5.10.2 Industrial segment 133 5.10.3 Colour filters for LCDs (Liquid crystal displays) 134 5.10.4 Ink jet printing of textiles 134 5.11 Toxicology and the environment 136 5.12 Future of ink jet 137 References 138

6 Thermal printing 139 R. BRADBURY

6.1 Introduction 139 6.2 Direct thermal printing 140 6.2.1 Colour formers 142 6.2.2 Developers 144 6.2.3 Sensitisers 145 6.2.4 Multicolour 147 6.2.5 Direct thermal markets 149 6.3 Mead Cycolor process 149 6.3.1 Photoinitiators 150 6.4 Dye-diffusion thermal transfer (D2T2) 151 6.4.1 Dye sheet (dye donor sheet) 152 6.4.2 Receiver sheet 154 6.4.3 Dye-diffusion thermal-transfer dyes 155 6.4.4 D2T2 market 162 Xll CONTENTS

6.5 Thermal-melt transfer 6.5.1 Dyesheet 6.5.2 Melt-transfer colorants 6.5.3 Receiver sheets 6.5.4 Printing 6.5.5 Thermal melt-transfer market References

7 Optical data-storage systems P.A. HUNT

7.1 Introduction 7.2 Principles of operational functionality 7.2.1 Read-only memory (ROM) 7.2.2 Erasable versus write-once 7.2.3 Physical and chemical requirements 7.3 System options 7.3.1 Metallic ablative (WORM) 7.3.2 Metallic phase-change (WORM and erasable) 7.3.3 Dye-polymer ablative (WORM) 7.3.4 Photochrome dye (erasable) 7.3.5 Liquid crystals (WORM and erasable) 7.3.6 Metallic interference (WORM) 7.4 Technical performance features of ODS systems 7.4.1 Performance advantages of ODS systems 7.4.2 Performance limitations in ODS systems 7.5 Commercial performance features 7.6 Comparison with alternative technologies 7.6.1 Magnetic media 7.6.2 Magneto-optical (MO) media 7.7 Related technologies 7.8 Applications of ODS 7.9 Toxicology and environmental considerations 7.10 The future References

8 Electrostatic, ionographic, magnetographic and embry printing technologies P. GREGORY

8.1 Introduction 8.2 Electrographic printing 8.3 Ionographic printing 8.4 Magnetographic printing 8.5 Embryonic printing technologies 8.5.1 High-resolution dry-processing film (VerdeFilm) 8.5.2 Toner fusion xeroprinting 8.5.3 TonerJet 8.6 Future prospects References CONTENTS ХШ

9 The future 208 P. GREGORY

9.1 Introduction 208 9.2 Short-term predictions 208 9.2.1 Traditional printing and imaging 208 9.2.2 Non-impact printing and imaging 209 9.3 Longer-term predictions 209 9.3.1 Evolutionary developments 209 9.3.2 Revolutionary developments 210 9.4 Conclusion 213 References 213

Index 214