High-Technology Applications of Organic Colorants

Transcription

1 High-Technology Applications of Organic Colorants Peter Gregory Specialties Research Centre ICI Specialties Imperial Chemical Industries PLC Blackley, Manchester, England Plenum Press New York and London

2 Contents PART I. Historical Perspectives PART II. Colorants for Electronics 1. Liquid Crystal Dyes 1.1. Introduction Dye Types Future Trends Summary 13 References Micro Color Filters 2.1. Introduction Fiat Screen Televisions Color Filter Preparation Dyeing Method Pigment Method Spectral Characteristics Summary 24 References Laser Dyes 3.1. Introduction Basic Theory Dye Types Summary 31 References 32 ix

3 X Contents 4. Colorants for Nonlinear Optics 4.1. Introduction Nonlinear Optical Effects and Applications Molecular Polarizability Nonlinear Optical Molecules Molecular Alignment Summary 43 References Solar Cells 5.1. Introduction Photosynthesis Mimics Miscellaneous Colorants Luminescent Solar Cells Applications Summary 51 References Electrochromic Dyes 6.1. Introduction Electrochromic Displays Electrochromic Printing Summary 55 References 56 PART III. 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

4 Contents XI 7.5. Toners General Features Charge Control Agents Negative Charge Control Agents Positive Charge Control Agents Noncolored Charge Control Agents Polymerie Charge Control Agents Mode of Action Colored Toners Photoactive Pigment Electrophoresis Basic Process Füll Color Process Problems of Photoactive Pigment Electrophoresis Correlation with Organic Photoconductors Special Effects Nonphotocopiable Documents Photomicrolithography Prepress Proofing Transfer Printing Toners Summary 118 References Thermography 8.1. Introduction Direct Thermal Printing Pressure-Sensitive Printing Mead Photocapsule (CYCOLOR) Process 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 YellowDyes Magenta Dyes CyanDyes Receiver Sheet 168

5 Xll Contents 8.7. Summary 169 References Ink-Jet Printing 9.1. Introduction History and Development Technology Continuous Ink-Jet Drop-on-Demand Ink-Jet Ink-Jet Inks General Features Aqueouslnks Solvent Inks Hot-Melt Inks Ink-Paper Interactions Ink-Jet Colorants Properties Required Color Color Strength Solubility Insolubles Electrolytes/Metals Fastness Properties 188 a. Light Fastness 188 b. Water Fastness 188 c. Smear Fastness Shade Toxicology Thermal Stability DyeTypes Black Dyes Water Soluble Solvent/Resin Soluble Yellow Dyes Water Soluble Solvent/Resin Soluble Magenta Dyes Water Soluble Solvent/Resin Soluble CyanDyes Water Soluble Solvent/Resin Soluble 201

6 Contents XÜi 9.6. Applications of Ink-Jet Printing Summary 203 References Electrography, lonography, and Magnetography Introduction Electrography lonography Magnetography Summary 212 References 212 PART IV. Future Perspectives 11. Infrared Absorbers Introduction Effects of Infrared 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 Polymorphie Pigments Metallation Donor Substitutents Extended Conjugation Azo Indoanilines Donor-Acceptor Molecules ' OtherClasses 243

7 XIV Contents 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 251 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 259 b. Nitrosamines 260 c. Hydrazines and Hydroxylamines d. Azo Dyes 264 e. Anthraquinone Dyes 266 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 272 References Future Trends Introduction Colorants for Electronics 273

8 Contents XV Colorants for Reprographics The Paperless Office Competing Technologies General Predictions Specific Predictions Electrophotography Thermal Ink-Jet Other Technologies Toxicology Summary 283 Reference 283 Index 285