High-Technology Applications of Organic Colorants

Transcription

1 High-Technology Applications of Organic Colorants

2 TOPICS IN APPLIED CHEMISTRY Series Editors: Alan R. Katritzky, FRS Kenan Professor of Chemistry University of Florida, Gainesville, Florida Gebran J. Sabongi Laboratory Manager, Encapsulation Technology Center 3M, St. Paul, Minnesota BIOCATALYSTS FOR INDUSTRY Edited by Jonathan S. Dordick CHEMICAL TRIGGERING Reactions of Potential Utility in Industrial Processes Gebran J. Sabongi THE CHEMISTRY AND APPLICATION OF DYES Edited by David R. Waring and Geoffrey Hallas HIGH-TECHNOLOGY APPLICATIONS OF ORGANIC COLORANTS Peter Gregory INFRARED ABSORBING DYES Edited by Masaru Matsuoka STRUCTURAL ADHESIVES Edited by S. R. Hartshorn TARGET SITES FOR HERBICIDE ACTION Edited by Ralph C. Kirkwood A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher.

3 High-Technology Applications of Organic Colorants Peter Gregory Specialties Research Centre ICI Specialties Imperial Chemical Industries PLC Blackley, Manchester, England Springer Science+Business Media. llc

4 Llbrary of Congress Cataloglng-ln-Publlcatlon Data Hlgh-technology applications of organic colorants I Peter Gregory. p. cm. -- (Topics in applied chemistry) Includes bibliographical references and index. ISBN ISBN (ebook) DOI / Dyes and dyeing--chemistry. 1. Gregory, P. (Peter), II. Series. TP910.H '.2--dc CIP 1991 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1991 AlI rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

5 For my wife, Vera, and my two sons, Andrew and Michael

6 Preface The traditional use of organic colorants is to impart color to a substrate such as textiles, paper, plastics, and leather. However, in the last five years or so organic colorants have become increasingly important in the hightechnology (hi-tech) industries of electronics and particularly reprographics. In some of these reprographics applications the organic colorant is used in its traditional role of imparting color to a substrate, typically paper or plastic. Examples are dyes for ink-jet printing, thermally transferable dyes for thermal transfer printing, and dyes and pigments for colored toners in photocopiers and laser printers. In other applications it is a special effect of an organic colorant that is utilized, not its color. Examples are electrical effects, such as photoconduction and the electrostatic charging of toners, both of which are essential features for the operation of photocopiers and laser printers, and the selective absorption of infrared radiation, which is utilized in optical data storage. In electronic applications the organic colorant is often employed in a device. Typical examples include liquid crystal dyes, laser dyes, electrochromic dyes, dyes for solar cells, dyes for micro color filters, and dyes for nonlinear optical applications. These hi-tech applications present many challenges to the dyestuff chemist to devise dyes to meet the often demanding criteria required. This book describes how those challenges are being met in the important electronics and reprographics technologies. It also illustrates the vital role that organic colorants play in these applications. Indeed, it gives a chemist's view rather than a physicist's or engineer's view of the electronics and reprographics technologies. The traditional uses of colorants are well documented in books such as those by Gordon and Gregory/ Allen/ and Zollinger/ and especially in the comprehensive volumes of Venkataraman;4 they are not discussed further here. Neither are some of the less traditional, more diverse uses of colorants, vii

7 viii Preface such as their applications in medicine, security, toiletries, fuel and metal coloration, thermochromic systems, photochromie systems, and many other areas. Modern biological uses of dyes, such as affinity chromatography to obtain highly pure enzymes from gross mixtures, also are not discussed, since these are treated adequately elsewhere. 5 Acknowledgment I would like to thank the many people who have helped me in the preparation of this book. Firstly, my colleagues in the Colours and Fine Chemicals Research Centre of ICI Specialties for their suggestions and support, including the Research Manager, Alan Calder, for allowing me access to computer print-out and photocopying facilities and especially Annmarie Anderson, Prahlad Mistry, and Paul Simpson for producing the excellent figures. Secondly, the people who have kindly read the entire manuscript and made many valuable comments. These include people from academic establishments, such as Prof. C. W. Rees (Imperial College, London) and Dr. J. Griffiths (Leeds University); people from industrial establishments in Europe, such as Dr. D. E. Wilson (Coates Electrographies) and Dr. D. Wallace (De La Rue); and people from the United States, such as Dr. G. Baxter (Moore Business Forms) and Dr. R. Dessauer and Dr. W. Solodar (DX Imaging). Last, but by no means least, I thank my family. My wife, Vera, for her patience and understanding and for typing the entire manuscript on my home wordprocessor, and my two sons Andrew and Michael for not complaining too much. REFERENCES 1. P. F. Gordon and P. Gregory, Organic Chemistry in Color, Springer-Verlag, Berlin (1983). 2. R. L. M. Allen, Color Chemistry, Nelson, London (1971). 3. H. Zollinger, Color Chemistry: Synthesis, Properties and Applications of Organic Dyes and Pigments, VCH Publications, Weinheim, Germany, (1987). 4. The Chemistry of Synthetic Dyes (K. Venkataraman, ed.), Vols. I-VIII, Academic Press, New York (1952). 5. P. F. Gordon and P. Gregory, in: Critical Reviews in Applied Chemistry (1. Griffiths, ed.), Vol. 7, pp , Blackwell, Oxford (1984).

8 Contents PART I. Historical Perspectives PART II. Colorants for Electronics 1. Liquid Crystal Dyes 1.1. Introduction Dye Types Future Trends 1.4. Summary. References Micro Color Filters 2.1. Introduction Flat Screen Televisions Color Filter Preparation Dyeing Method Pigment Method 2.4. Spectral Characteristics 2.5. Summary. References Laser Dyes 3.1. Introduction Basic Theory 3.3. Dye Types 3.4. Summary. References ix

9 x 4. Colorants for Nonlinear Optics 4.1. Introduction Nonlinear Optical Effects and Applications 4.3. Molecular Polarizability Nonlinear Optical Molecules 4.5. Molecular Alignment Summary. References.... Contents Solar Cells 5.1. Introduction Photosynthesis Mimics Miscellaneous Colorants Luminescent Solar Cells Applications Summary. References Electrochromic Dyes 6.1. Introduction Electrochromic Displays Electrochromic Printing Summary. References PART HI. Colorants for Reprographics 7. Electrophotography 7.1. Introduction Photocopying and Laser/Light Emitting Diode Printing Processes Photocopying Process Laser/Light Emitting Diode Printing Process Color Copying Process Key Chemical Components Photoconductors General Features Inorganic Photoconductors Organic Photoconductors Photoconductive Mechanism. 86

10 Contents 7.5. Toners General Features Charge Control Agents Negative Charge Control Agents Positive Charge Control Agents Noncolored Charge Control Agents Polymeric Charge Control Agents Mode of Action Colored Toners Photoactive Pigment Electrophoresis Basic Process Full Color Process Problems of Photoactive Pigment Electrophoresis Correlation with Organic Photoconductors 7.7. Special Effects N onphotocopiable Documents Photomicrolithography Prepress Proofing Transfer Printing Toners 7.8. Summary. References Thermography 8.1. Introduction Direct Thermal Printing Pressure-Sensitive Printing Mead Photocapsule (CYCOLOR) Process 8.5. Thermal Wax Transfer Color Sheet Receiver Sheet Patent Activity Electrothermal Printing Laser Transfer Dye Diffusion Thermal Transfer Electronic Photography History and Development Dye Diffusion Thermal Transfer Process Dyesheet Dye Diffusion Thermal Transfer Dyes Yellow Dyes Magenta Dyes Cyan Dyes Receiver Sheet.... xi

11 xii 8.7. Summary. References Contents Ink-Jet Printing 9.1. Introduction History and Development 9.3. Technology Continuous Ink-Jet Drop-on-Demand Ink-Jet Ink-Jet Inks General Features Aqueous Inks Solvent Inks Hot-Melt Inks Ink-Paper Interactions Ink-Jet Colorants Properties Required Color Color Strength Solubility Insolubles Electrolytes/Metals Fastness Properties a. Light Fastness. b. Water Fastness. c. Smear Fastness Shade Toxicology Thermal Stability Dye Types Black Dyes Water Soluble Solvent/Resin Soluble Yellow Dyes Water Soluble Solvent/Resin Soluble Magenta Dyes Water Soluble Solvent/Resin Soluble Cyan Dyes Water Soluble Solvent/Resin Soluble

12 Contents 9.6. Applications of Ink-Jet Printing 9.7. Summary. References xiii Electrography, Ionography, and Magnetography Introduction Electrography Ionography Magnetography Summary. References PART IV. Future Perspectives 11. Infrared Absorbers Introduction Effects ofinfrared Absorbers Classification of Infrared Absorbers Nitroso Cyanines Nigrosines Triphenylmethanes Imminium and Diimminium Squariliums and Croconiums Nickel Dithiolenes and Related Compounds Quinones Simple Naphthoquinones Extended Quinones CI Disperse Blue 60 Analogues Benzoquinones Phthalocyanines Polymorphic Pigments Metallation Donor Substitutents Extended Conjugation Azo Indoanilines Donor-Acceptor Molecules Other Classes

13 xiv Cootents Applications of Infrared Absorbers Heat-Ray Blocking Energy Conversion Thermal Imaging Flash Fusion of Toners Solar Heating Optical Effects (Utilizing Laser Radiation) Organic Photoconductors Optical Data Storage Automatic Identification Optical Effects (Utilizing Electromagnetic Radiation) Colorless Infrared Absorbers Summary. References Toxicology Introduction Hazards of Colorants Regulations and Registration Structure-Carcinogenicity Guidelines for Organic Colorants and Related Intermediates Effect of Physical Properties on Carcinogenicity Classes of Carcinogens by Chemical Structure Carcinogens from Nitrogen Electrophiles a. Aromatic Nitro and Amino Compounds b. Nitrosamines c. Hydrazines and Hydroxylamines. d. Azo Dyes... e. Anthraquinone Dyes..... f. Cationic Dyes Carcinogens from Carbon Electrophiles. a. Direct Acting Alkylating Agents. b. Polycyclic Aromatic Hydrocarbons c. Michael Acceptors Metals Carcinogenic Impurities Risk Assessment Summary. References. 13. Future Trends Introduction Colorants for Electronics

14 Contents Colorants for Reprographics The Paperless Office Competing Technologies General Predictions Specific Predictions Electrophotography Thermal Ink-Jet Other Technologies Toxicology S1)tIlmary. Reference. xv Index