Chemistry and Technology of

Water Based Inks

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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

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, 69469 Weinheim, Germany

Chapman & Hall USA, 115 Fifth Avenue, New York, NY 10003, USA

Chapman & Hall Japan, lIP-Japan, Kyowa Building, 3F, 2-2-1 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 600 035, India

First edition 1997

© 1997 Chapman & Hall Softcover reprint of the hardcover 1 st edition 1997 Typeset in 10/12 Times by Blackpool Typesetting Services Limited, UK

ISBN-I 3:978-94-010-7 190-1 DOl: 1 0.1 007/978-94-009-1547-3

e-ISBN-I 3:978-94-009-1 547-3

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A catalogue record for this book is available from the British Library

Library of Congress Catalog Card Number: 96-83829

@) Printed on acid-free text paper, manufactured in accordance with ANSIINISO Z39.48-1992 (Permanence of Paper)

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

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 19004-2134, 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-63457 Hanau, Germany

President, PF Technical Services, 210 Stephen Street, Levittown, NY 11756, USA

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 19341-1393, USA

Contents

1 Introduction 1 F. SHAPIRO and D. SAGRAVES 1.1 Environmental considerations for water based inks I

1.1.1 Effect on the ink and printing industry I 1.1.2 Printing inks as a source of pollution 2 1.1.3 Clean air initiatives in the United States 3 1.1.4 The disposal of hazardous waste 4 1.1.5 CERCLA and the Superfund Amendments and Reauthorization Act 5 1.1.6 Water pollution control 5 1.1.7 Chemicals in the workplace 6 1.1.8 Regional impact on regulations 7 1.1.9 Why water based ink formulations? 7 1.1.10 Concerns with the transfer to water based inks 7

1.2 Factors affecting the change to water based inks 8 1.2.1 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 12 2.2 Elements needed to describe color 12

2.2.1 The sample 12 2.2.2 The light source 13 2.2.3 The observer 14

2.3 The CIE system 16 2.3.1 Source and illuminat 17 2.3.2 2° Observer-10° observer 17 2.3.3 Computation of CIE tristimulus values, X, Y, Z 17 2.3.4 Chromaticity coordinates and the chromaticity diagram 18 2.3.5 Color difference calculations and the chromaticity

diagram 20 2.4 Applications of the 1976 CIE L *a*b* formula for the

calculation of color tolerances 22 2.4.1 Color sensation 22 2.4.2 CIE 1976 L *a*b* (CIELAB) color space 24 2.4.3 Choice of color difference components 27 2.4.4 The CMC color tolerance formula 30

2.5 Calculations: detailed example 32 2.5.1 Calculation of tristimulus values X, Y, Z 33 2.5.2 Calculation of L *, a*, b*, C* 36 2.5.3 Metamerism 38

2.6 CIELAB color difference equations 39 2.6.1 CIE L*a*b* 40 2.6.2 CMC 40 2.6.3 Concept of unit volume/tolerance 41 References 42

X CONTENTS

3 Flexographic printing presses 43 D.TUTTLE

3.1 Introduction 43 3.1.1 Versatility of flexo presses 44 3.1.2 The flexo press as an excellent coating machine 44 3.1.3 A change in webbing 45 3.1.4 Expanding the usefulness of a flexo press 46

3.2 Evolution of flexo-type litho 49 3.2.1 Flexo-type ink systems 50 3.2.2 Advances in Flexo systems and related processes 52

3.3 Testing incoming inks 55 3.3.1 Six simple tests 56

3.4 Viscosity as a measurement to make production flow 58 3.4.1 Yield value of a liquid 59 3.4.2 Confused by viscosity? 60 3.4.3 Measuring the value of controls 61 3.5.4 The obvious conclusions 61

3.5 A unit that enables variable control of ink density and thickness 62 3.5.1 Various density control 62 3.5.2 Two rollers and doctor blade 63

3.6 Drying of inks 64 3.6.1 Concept of boundary layer 65 3.6.2 Effect of air velocity 66 3.6.3 How dry is dry? 67 3.6.4 Residual solvent standards 68

3.7 Evaluation of anilox rolls 68 3.7.1 Some standards for ani lox rolls 69 3.7.2 The importance of cell volume 69 3.7.3 What to use, and when 71 3.7.4 Anilox roll chart 72

3.8 The reverse-angle doctor blade and ani lox rolls 73 3.8.1 Pneumatics used on corrugated presses 75 3.8.2 Doctor blade forms fountain 75 3.8.3 Pressure by expandable tube 76 3.8.4 Advantages of the doctor blade system 76

3.9 How the reverse-angle doctor blade works, and a comparison with other metering systems 77 3.9.1 Development of flexo ink distribution systems 78

3.10 Advantages and disadvantages of the reverse-angle ani lox blade 82 3.10.1 Applications in newspaper printing 85

3.11 Overcoming moire effects in flexography 88 3.11.1 Tone and process anilox rolls 89 3.11.2 Creating moire patterns 89 3.11.3 Plate screen versus ani lox screen 90 3.11.4 Basic principles of moire 93

3.12 Drying power of inks 97 3.12.1 Hot air drying systems 98 3.12.2 When is a flexo ink dry? 99 3.12.3 Turbulence at the boundary layer as an aid to drying efficiency 100

3.13 Variations in thickness of substrates 104 3.13.1 Common problems 105 3.13.2 Compressibility of plate mounting material 105

3.14 Flexographic printing on corrugated board 107 3.14.1 When ink gets to the plate 108 3.14.2 How level is the substrate? 109 3.14.3 VIP plate performs efficiently 109 3.14.4 How much relief) 110 3.14.5 Harder plates may be better 110

4 Pigments C. DURGAN and E. REICH

4.1 Pigments for printing inks 4.2 Classification of pigments

4.2.1 Color index system 4.3 Pigment composition

4.3.1 Azo pigments 4.3.2 Metallized azo pigments

CONTENTS

4.3.3 Non-metallized disazo pigments 4.3.4 Phthalocyanine pigments 4.3.5 Dioxazine violet pigments 4.3.6 Triphenylmethane pigments 4.3.7 Benzimidazolone pigments 4.3.8 Quinacridone pigments 4.3.9 Inorganic pigments

4.4 Manufacture of azo pigments 4.4.1 Diazotization 4.4.2 Coupling 4.4.3 Metallization 4.4.4 After-treatment 4.4.5 Filtering, drying and grinding of azo pigments

4.5 Pigments produced from crudes 4.5.1 Phthalocyanine blue 4.5.2 Metal-free phthalocyanine blue 4.5.3 Phthalocyanine green 4.5.4 Carbazole violet 4.5.5 Quinacridone reds and violets 4.5.6 Pigments produced from dyes 4.5.7 Inorganic pigments: manufacture of C.I. Pigment Blue

27 (milori blue) 4.6 Advantages and disadvantages of dry pigments in a water based system

4.6.1 Proper pigment selection 4.6.2 Resination 4.6.3 Pigment/vehicle compatibility and stability 4.6.4 Production of high-quality dispersions using dry color 4.6.5 Ease of dispersion

4.7 Handling dry pigments 4.7.1 Physical and health hazards 4.7.2 Industrial uselhazard communication 4.7.3 Environmental concerns

4.8 Marketplace analysis for dry pigments 4.9 Water based pigment dispersions 4.1 0 Pigment structures References Bibliography

5 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

5.4.1 Particle size and surface area 5.4.2 Structure 5.4.3 Surface chemistry

Xl

111

111 111 III 114 114 115 118 119 120 120 121 121 122 123 122 123 124 124 124 124 124 127 127 128 128 129

129 129 129 133 133 135 137 137 138 138 139 139 141 143 143 143

153

153 154 156 161 161 164 166

Xli CONTENTS

5.4.4 Further testing methods 167 5.5 Applications of carbon black 168 References 174

6 Solvents T. HOLSHUE and H. GAINES

6.1 6.2

Introduction Glycol ether solvents for water based ink applications 6.2.1 6.2.2

6.2.3 6.2.4

6.2.5 6.2.6 6.2.7

6.2.8

6.2.9 6.2.10 6.2.11

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

175

175 178 178

181 184

185 186 187

187

187 187 188 189

7 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 190 7.2 Reduction of volatile organic compounds through aqueous acrylic polymers 197

7.2.1 Comparison of water based and solvent based ink requirements 197 7.2.2 Alkali soluble resins 198 7.2.3 Selection of alkali soluble resins 199 7.2.4 Acrylic emulsions 200 7.2.5 Selection of acrylic emulsions 201 7.2.6 Colloidal emulsions and solutions 202 7.2.7 Acrylic specialty polymers 203 7.2.8 Trends for the future 204

7.3 The waterborne way 205

8 Additives A.C.D. COWLEY and T. WALSH

8.1 Hyperdispersants: the problem solvers 8.1.1 The problems 8.1.2 Hyperdispersants 8.1.3 Use of hyperdispersants 8.1.4 Solving the problems 8.1.5 Summary

8.2 Defoaming agents 8.2.1 Foam 8.2.2 New defoaming products 8.2.3 Future defoaming agents References

208

208 208 209 211 213 216 216 217 218 219 219

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 9.1.1 Base ink systems 9.1.2 Extenders 9.1.3 Heavy ink systems 9.1.4 Standard ink systems (flexographic) 9.1.5 Standard ink systems (gravure) 9.1.6 Formulation 9.1.7 A method for determining the performance of

water based inks 9.2 Scratch-off inks and coatings

9.2.1 Hiding properties 9.2.2 Application method for scratch-off inks and coatings 9.2.3 Substrate on which the message will be printed 9.2.4 Drying conditions 9.2.5 Properties required for the finished coating 9.2.6 A formula for a scratch-off coating Appendix 9.A: data for design and formulation

xiii

220

220 221 221 222 222 222 224

226 229 229 230 232 233 234 234 235

10 Particle size reduction of pigments using a small media mill 255 H.W. WAY 10.1 Introduction 255 10.2 Machine design 256 10.3 Machine operation 258 10.4 Controlling factors in milling 260 10.5 Mill design 263 10.6 Agitation systems 265 10.7 Applications 270 10.8 Conclusions 272 References 272

11 Dispersion of low viscosity water based inks 273 J.A. SCHAK

11.1 Introduction 273 11.2 Background 273 11.3 Major dispersion steps 275 11.4 Dispersion equipment design 275 11.5 Choosing a dispersion line 277 11. 6 One-step processes 277

11.6.1 'Sawtooth' blade or HSD mixers 277 11.6.2 Rotor-stator homogenizer (5000 feet/min tip speeds) 279 11.6.3 Rotor-stator mills (9000 + feet/min speeds) 279

11.7 MUltiple step processes (final media milling) 282 11.7.1 Small media mill design 282 11.7.2 'Sawtooth' blade mixer followed by a small media mill 284 11.7.3 Rotor-stator mill followed by a media mill 284 11. 7.4 Rotor-stator mill followed by a small media mill then a micro media mill 285 11.7.5 Rotor-stator mill with a hi-flow recirculation mill 286 11.7.6 Example of rotor-stator mill with a hi-flow recirculation mill 287 II. 7.7 Debottlenecking existing dispersion lines 287 11.7.8 Continuous inline rotor-stator mill 287

11.8 Summary 289 References 289

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

290 290 290 297 304 307 308 309 311 311 319 329 333

339

343