Chemistry and Technology. Water Based Inks

Transcription

1 Chemistry and Technology of Water Based Inks

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3 Chemistry and Technology of Water Based Inks Edited by P. LADEN BLACKIE ACADEMIC & PROFESSIONAL An Imprint of Chapman & Hall London Weinheim. New York Tokyo Melbourne Madras

4 Published by Blackie Academic and Professional, an imprint of Chapman & Hall, 2--{j Boundary Row, London SEt 8HN, UK Chapman & Hall, 2--6 Boundary Row, London SEI 8HN, UK Chapman & Hall, GmbH, Pappelallee 3, Weinheim, Germany Chapman & Hall USA, 115 Fifth Avenue, New York, NY 10003, USA Chapman & Hall Japan, lip-japan, Kyowa Building, 3F, Hirakawacho, Chiyoda-ku, Tokyo 102, Japan DA Book (Aus!.) Pty Ltd, 648 Whitehorse Road, Mitcham 3132, Victoria, Australia Chapman & Hall India, R. Seshadri, 32 Second Main Road, CII East, Madras , India First edition Chapman & Hall Softcover reprint of the hardcover 1 st edition 1997 Typeset in 10/12 Times by Blackpool Typesetting Services Limited, UK ISBN-I 3: DOl: / e-isbn-i 3: 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 repro graphic 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 London 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 catalogue record for this book is available from the British Library Library of Congress Catalog Card Number: Printed on acid-free text paper, manufactured in accordance with ANSIINISO Z (Permanence of Paper)

5 Preface This book has been a long time in the making. Since its beginning the concept has been refined many times. This is a first attempt at a technical book for me and fortunately the goals I have set have been achieved. I have been involved in water based ink evaluation since its unclear beginnings in the early 1970s. This book is fashioned much like a loose-leaf binder I had put together for early reference and guidance. The format has worked for me over the years; I trust it will work for you. I would like to thank the many people who made this book possible, particularly Blackie Academic & Professional for their saint-like patience. Thanks again to W.B. Thiele (Thiele-Engdahl), to Lucille, my wife, and to James and Frank, my two boys. A final and special thank you to Richard Bach who taught me there are no limits. Patrick Laden Anna Maria Island, Florida

6 Contributors G.H. Cabiro A.C.D. Cowley M.A. Dalton C. Durgan S. Fingerman H. Gaines R.P. Grandke H.J. Hartschuh T.R. Holshue P. Laden G. Oliver E. Reich D. Sagraves J.A. Schak W. Schumacher F. Shapiro SC Johnson Polymers, 1525 Howe Street, Racine, WI 53403, USA Zeneca Ltd, Wilmington, DE, USA SC Johnson Polymers, 1525 Howe Street, Racine, WI 53403, USA Business Manager (Fluid Inks), Pigments Div., Sun Chemical Corp., 411 Sun Avenue, Cincinnati, OH 45232, USA President, Garln Graphics, PO Box 1621, Cranford, NJ 07016, USA American Ink Maker, Melville, NY, USA SC Johnson Polymers, 1525 Howe Street, Racine, WI 53403, USA SC Johnson Polymers, 1525 Howe Street, Racine, WI 53403, USA President, WN Stevenson Co., 246 Rock Hill Road, Bala Cynwyd, PA , USA Kohl & Madden Printing Ink Corp., 9025 Junction Drive, Annapolis Junction, MD 20701, USA SC Johnson Polymers, 1525 Howe Street, Racine, WI 53403, USA Reich Corporation, 3146 Marion Street, Reading, PA 19405, USA Technical Marketing Manager, Ink Division, General Printing, PO Box 2037, NC 28241, USA Kady International, Pleasant Hill Road, Scarboro, ME, USA Jakob-Altmaier-StraBe 15, D Hanau, Germany President, PF Technical Services, 210 Stephen Street, Levittown, NY 11756, USA

7 viii T. Smith D. Tuttlet T. Walsh H.W. Way CONTRIBUTORS SC Johnson Polymers, 1525 Howe Street, Racine, WI 53403, USA Flexographic Technical Association, USA Ultra Additives, Park Station, Patterson, NJ, USA Dispersion Equipment Division, Netzsch Inc., 119 Pickering Way, Exton, PA , USA

8 Contents 1 Introduction 1 F. SHAPIRO and D. SAGRAVES 1.1 Environmental considerations for water based inks I Effect on the ink and printing industry I Printing inks as a source of pollution Clean air initiatives in the United States The disposal of hazardous waste CERCLA and the Superfund Amendments and Reauthorization Act Water pollution control Chemicals in the workplace Regional impact on regulations Why water based ink formulations? Concerns with the transfer to water based inks Factors affecting the change to water based inks What can a printer do to maintain press speeds with water based inks? 9 2 Colorimetry and the calculation of color difference 12 P.l. LADEN 2.1 Introduction Elements needed to describe color The sample The light source The observer The CIE system Source and illuminat Observer-10 observer Computation of CIE tristimulus values, X, Y, Z Chromaticity coordinates and the chromaticity diagram Color difference calculations and the chromaticity diagram Applications of the 1976 CIE L *a*b* formula for the calculation of color tolerances Color sensation CIE 1976 L *a*b* (CIELAB) color space Choice of color difference components The CMC color tolerance formula Calculations: detailed example Calculation of tristimulus values X, Y, Z Calculation of L *, a*, b*, C* Metamerism CIELAB color difference equations CIE L*a*b* CMC Concept of unit volume/tolerance 41 References 42

9 X CONTENTS 3 Flexographic printing presses 43 D.TUTTLE 3.1 Introduction Versatility of flexo presses The flexo press as an excellent coating machine A change in webbing Expanding the usefulness of a flexo press Evolution of flexo-type litho Flexo-type ink systems Advances in Flexo systems and related processes Testing incoming inks Six simple tests Viscosity as a measurement to make production flow Yield value of a liquid Confused by viscosity? Measuring the value of controls The obvious conclusions A unit that enables variable control of ink density and thickness Various density control Two rollers and doctor blade Drying of inks Concept of boundary layer Effect of air velocity How dry is dry? Residual solvent standards Evaluation of anilox rolls Some standards for ani lox rolls The importance of cell volume What to use, and when Anilox roll chart The reverse-angle doctor blade and ani lox rolls Pneumatics used on corrugated presses Doctor blade forms fountain Pressure by expandable tube Advantages of the doctor blade system How the reverse-angle doctor blade works, and a comparison with other metering systems Development of flexo ink distribution systems Advantages and disadvantages of the reverse-angle ani lox blade Applications in newspaper printing Overcoming moire effects in flexography Tone and process anilox rolls Creating moire patterns Plate screen versus ani lox screen Basic principles of moire Drying power of inks Hot air drying systems When is a flexo ink dry? Turbulence at the boundary layer as an aid to drying efficiency Variations in thickness of substrates Common problems Compressibility of plate mounting material Flexographic printing on corrugated board When ink gets to the plate How level is the substrate? VIP plate performs efficiently How much relief) Harder plates may be better 110

10 CONTENTS Xl 4 Pigments C. DURGAN and E. REICH 4.1 Pigments for printing inks 4.2 Classification of pigments Color index system 4.3 Pigment composition Azo pigments Metallized azo pigments Non-metallized disazo pigments Phthalocyanine pigments Dioxazine violet pigments Triphenylmethane pigments Benzimidazolone pigments Quinacridone pigments Inorganic pigments 4.4 Manufacture of azo pigments Diazotization Coupling Metallization After-treatment Filtering, drying and grinding of azo pigments 4.5 Pigments produced from crudes Phthalocyanine blue Metal-free phthalocyanine blue Phthalocyanine green Carbazole violet Quinacridone reds and violets Pigments produced from dyes Inorganic pigments: manufacture of C.I. Pigment Blue 27 (milori blue) 4.6 Advantages and disadvantages of dry pigments in a water based system Proper pigment selection Resination Pigment/vehicle compatibility and stability Production of high-quality dispersions using dry color Ease of dispersion 4.7 Handling dry pigments Physical and health hazards Industrial uselhazard communication Environmental concerns 4.8 Marketplace analysis for dry pigments 4.9 Water based pigment dispersions Pigment structures References Bibliography III Carbon black W. SCHUMACHER 5.1 Classification and types of carbon black 5.2 Composition of carbon black 5.3 Manufacture of carbon black 5.4 Properties and testing methods of carbon black Particle size and surface area Structure Surface chemistry

11 Xli CONTENTS Further testing methods Applications of carbon black 168 References Solvents T. HOLSHUE and H. GAINES Introduction Glycol ether solvents for water based ink applications Properties of glycol ethers Butyl cellosolve solvent (ethylene glycol monobutyl ether) Inverse solubility Hexyl cellosolve solvent (ethylene glycol monohexyl ether) Methyl carbitol solvent (diethylene glycol monoethyl ether) Carbitol solvent (diethylene glycol monoethyl ether) Butyl carbitol solvent (diethylene glycol monobutyl ether) Hexyl carbitol solvent (diethylene glycol monohexyl ether) Alkoxytriglycols Storage of glycol ethers Hazards of glycol ethers Emulsion and solution polymers 190 H.J. HART SCHUH, G.H. CABIRO, M.A. DALTON, R.P. GRANDKE, T. SMITH and G. OLIVER 7.1 Designing innovative water based polymers for graphic arts Reduction of volatile organic compounds through aqueous acrylic polymers Comparison of water based and solvent based ink requirements Alkali soluble resins Selection of alkali soluble resins Acrylic emulsions Selection of acrylic emulsions Colloidal emulsions and solutions Acrylic specialty polymers Trends for the future The waterborne way Additives A.C.D. COWLEY and T. WALSH 8.1 Hyperdispersants: the problem solvers The problems Hyperdispersants Use of hyperdispersants Solving the problems Summary 8.2 Defoaming agents Foam New defoaming products Future defoaming agents References

12 CONTENTS 9 Design and formulation of water based ink systems P.I. LADEN and S. FINGERMAN 9.1 Factors to be considered when designing a water based ink system Base ink systems Extenders Heavy ink systems Standard ink systems (flexographic) Standard ink systems (gravure) Formulation A method for determining the performance of water based inks 9.2 Scratch-off inks and coatings Hiding properties Application method for scratch-off inks and coatings Substrate on which the message will be printed Drying conditions Properties required for the finished coating A formula for a scratch-off coating Appendix 9.A: data for design and formulation xiii Particle size reduction of pigments using a small media mill 255 H.W. WAY 10.1 Introduction Machine design Machine operation Controlling factors in milling Mill design Agitation systems Applications Conclusions 272 References Dispersion of low viscosity water based inks 273 J.A. SCHAK 11.1 Introduction Background Major dispersion steps Dispersion equipment design Choosing a dispersion line One-step processes 'Sawtooth' blade or HSD mixers Rotor-stator homogenizer (5000 feet/min tip speeds) Rotor-stator mills ( feet/min speeds) MUltiple step processes (final media milling) Small media mill design 'Sawtooth' blade mixer followed by a small media mill Rotor-stator mill followed by a media mill Rotor-stator mill followed by a small media mill then a micro media mill Rotor-stator mill with a hi-flow recirculation mill Example of rotor-stator mill with a hi-flow recirculation mill 287 II. 7.7 Debottlenecking existing dispersion lines Continuous inline rotor-stator mill Summary 289 References 289

13 xiv CONTENTS Appendices Appendix A: Trouble-shooting guide Part I Manufacturing Part 2 Flexographic packaging printing Part 3 Packaging, gravure printing Part 4 Viscosity conversion guide Part 5 Ink mileage estimation Part 6 Viscosity (poise) Appendix B: Typical starting fonnulations for water based inks Part I General inks Part 2 Flexo/gravure inks Part 3 Flexo/roto inks Appendix C: Trademarked raw materials for typical water based inks Appendix D: Addresses of US suppliers of materials used in water based inks Index